Patent Application
20220161543
The present disclosure generally relates to dispensing of flowable materials and, more particularly, to a device, assembly, and method for loading nozzles with fluids of various viscosities.
In gravure printing, first, ink is applied to the overall surface of a body having a pattern of local indentations defined in the surface. Then, a sharp-edged doctor blade is used to scrape ink from the body surface, except for the ink collected within the indentations. Finally, the ink from within the indentations is transferred onto a substrate, such as paper, to produce a pattern of printed ink.
In gravure printing, the body is often in the form of a precise cylindrical roller (‘gravure roller’). The doctor blade contacts the outer surface of the gravure roller along a line parallel to the cylinder axis and is pressed against the ink-wetted surface of the body at a large angle to that surface (i.e., more than 45 degrees). The doctor blade is made with a precise straight edge so that it conforms closely to the un-indented regions of the cylinder surface.
Subsequent, under pressure, contact of the surface 116 with a surface 132 of a final substrate 130, such as paper, transfers ink from the indentations 118 onto the surface 132 of that final substrate 130. In this manner, the pattern of indentations is printed in ink on the final substrate 130.
As shown schematically in
In gravure printing, the purpose of the ink fountain is to deposit ink into the indentations of the gravure roller, while the purpose of the doctor blade is to remove ink from the un-indented regions of the roller surface. Any residual film of ink left on the gravure roller, after passing the doctor blade, is undesirable and therefore should be made as thin as possible. To achieve this, the edge of the doctor blade is narrow and presented at a large angle to the tangent (at the point where the gravure roller is contacted by the doctor blade) to the gravure roller surface. The combination of these two characteristics enables the doctor blade to exert high local pressure on any ink ‘lubricating film’ interposed between the edge of the doctor blade and roller surface, thereby making such a film very thin.
In a gravure printer, the pressurisation of the fluid that enables loading of the indentations is provided by the hydrostatic pressure due to gravity acting on the depth of ink into which the gravure roller is immersed. For example, a typical bath used for gravure printing, such as the ink reservoir 150, is about 10 cm deep, thus providing for the maximum pressure of about 1,000 Pa. As such, gravure printing is well-adapted to fully filling indentations of small volumes (e.g. less than 0.01 mm3) with liquid having a limited range of suitable rheological properties, in particular a low viscosity, e.g., less than 20.10−3 Pa·s. However, it would not be possible to achieve partial filling of such indentations. Furthermore, gravure printing is not well-adapted, and the pressure in the bath would be insufficient, to filling nozzles of volumes larger than 0.1 mm3 or with fluids having a wide range of rheological properties, such as a high viscosity, e.g., greater than 100.10−3 Ps·s. The gravure printing method is therefore not suitable for use with devices for depositing patterns of such larger fluid volumes and such larger fluid viscosity, such as devices described in WO 2017/141034 A1.
The disclosed embodiments describe a device for loading fluid into one or more nozzles of a nozzle-bearing body when the device is assembled into a working configuration with the nozzle-bearing body, the nozzle-bearing body having a body surface defining one or more orifices for receiving the fluid into the one or more nozzles. The device comprises a first member having a first surface; and a second member protruding from the first member, the second member having a second surface and a third surface, the second surface extending from the first surface at an interior angle in a range of 20 degrees to 160 degrees. The first surface is shaped to substantially complement the shape of the body surface. A tangent to the third surface, in a region of the third surface proximate to where the second surface meets the third surface, is substantially parallel to a tangent to the first surface, in a region of the first surface where the first surface meets the second surface, when the device is in the working configuration. The device has a recess defined therein at least in part by the first surface and the second surface, the recess configured to form a pocket for receiving the fluid when the device is assembled into the working configuration.
The third surface may be configured to conform to the shape of the body surface of the nozzle-bearing body when the device is in the working configuration and not to complement or substantially complement the shape of the body surface of the nozzle-bearing body when the device is outside the working configuration.
The interior angle may be in a range of 60 degrees to 120 degrees.
The interior angle may be in a range of 80 degrees to 100 degrees.
The interior angle may be 90 degrees.
The device may comprise: a third member extending from the first member and the second member, the third member having a fourth surface configured to face the body surface when the device is in the working configuration; and a fourth member extending from the first member and the second member opposite the third member, the fourth member having a fifth surface configured to face the body surface when the device is in the working configuration, where at least a portion of the fourth surface and at least a portion of the fifth surface extend from the opposite sides of the third surface to form with the third surface a single surface configured to conform to the body surface when the device is in the working configuration.
The third and fourth member may be integral with the first member and/or the second member.
The recess may further be defined by the third member and the fourth member.
The device may comprise a fifth member having a sixth surface extending from the first surface that is opposite where the first surface meets the second surface, where an angle formed by the sixth surface and the first surface is in a range of 185 degrees to 265 degrees, and where, the fifth member is configured to form a funnel between the sixth surface of the fifth member and the body surface for collecting fluid when the device is assembled into the working configuration.
The device may further comprise a first end member and a second end member positioned at the opposite sides of the device, where: the first end member has a seventh surface configured to conform to the shape of the body surface when the device is in the working configuration, the second end member has an eighth surface configured to conform to the shape of the body surface when the device is in the working configuration, and the seventh surface and the eighth surface comprise respective surface portions aligned with the third surface of the second member, thereby forming an extended surface including the third surface and configured to conform to the body surface when the device is in the working configuration.
The device may be configured such that, in the device assembled into the working configuration with the nozzle-bearing body, the pocket formed by the device and the nozzle-bearing body comprises an inner region for receiving fluid, the inner region defined at least by the first and second surfaces, and an outer region for receiving fluid, the outer region defined at least by the first and second end members and by an area of the sixth surface located between the first and second end members.
The end members may be detachably mounted on the device.
The device may be for loading fluid into one or more nozzles of the nozzle-bearing body that is planar. The first surface then may be planar such that the first surface is positionable to be substantially parallel to the planar body surface of the nozzle-bearing body and to define an opening with the planar body surface for receiving the fluid, when the device is in the working configuration being held proximate to the nozzle-bearing body with the second member protruding toward the planar body surface of the nozzle-bearing body.
The second surface may be substantially perpendicular to the first surface in a region where the second surface meets the first surface and may be substantially perpendicular to the third surface in a region where the second surface meets the third surface.
The device may be for loading fluid into one or more nozzles of the nozzle-bearing body that is cylindrical. The first surface then may have a cylindrical curvature and be positionable to be substantially concentric with the cylindrical body surface of the nozzle-bearing body and to define an opening with the cylindrical body surface for receiving the fluid when the device is in the working configuration being held proximate to the nozzle-bearing body with the second member protruding toward the cylindrical body surface of the nozzle-bearing body.
The second surface may be substantially perpendicular to the tangent to the first surface in a region where the second surface meets the first surface and be substantially perpendicular to the tangent to the third surface in a region where the second surface meets the third surface.
The device may satisfy the following relation: l1/cp>1, where: cp denotes an extent to which the third surface protrudes from the first surface, and l1 denotes a fluid-contacted length of the first surface measured along the first surface in the direction between the opening for receiving fluid and the second surface when the device is operated to load the fluid into the one or more nozzles.
The first member may be made of an engineering material, such as aluminium, brass, stainless steel, polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), nylon, carbon fibre composite, polyimide, or ultra-high molecular weight polyethylene (UHMWPE).
The second member may be made of a non-abrasive material, such as polytetrafluoroethylene (PTFE), ultra-high molecular weight polyethylene (UHMWPE), or nylon.
All portion(s) of the device that are configured to be pressed against the body surface of the nozzle-bearing body while the device is in the working configuration may be made of a non-abrasive material, such as polytetrafluoroethylene (PTFE), ultra-high molecular weight polyethylene (UHMWPE), or nylon.
The first member and the second member may form a unitary body of the device.
All members of the device may form the unitary body.
At least the first member and the second member may be separate parts joined together to form the device.
At least the first member and the second member may be made of different materials.
At least one member of the device is made of a material having low chemical reactivity.
The disclosed embodiments also describe an assembly for loading fluid. The assembly comprises: a nozzle-bearing body having a body surface defining one or more orifices for receiving the fluid into the one or more nozzles; and the above-described device for loading fluid. The device and the nozzle-bearing body are assembled into a working configuration in which the device is held proximate to the nozzle-bearing body such that the second member of the device protrudes toward the body surface and the first surface and the body surface form a pocket with an opening for receiving the fluid. In the working configuration, the nozzle-bearing body is movable relative to the device in a direction from the opening toward the second surface such that a gap formed between the first surface and the body surface and a gap formed between the third surface and the body surface remain substantially constant, thereby allowing the device to at least partially load the one or more nozzles with the fluid received into the pocket via the opening.
The assembly may satisfy the following relation: c1>>3Vn/An, where: c1 denotes the gap between the body surface and the first surface, 1/An refers to the number of nozzles per unit area in the region of the nozzle bearing body opposite the fluid filled region of the first surface, and Vn denotes a desired volume of fluid for loading into the fluid-contacted nozzle.
The assembly may satisfy the following relation: c2<cp, where: cp denotes an extent to which the third surface protrudes from the first surface, and c2 denotes the gap formed between the body surface and the third surface of the device.
The assembly may satisfy the following relation: c2<<cp.
The assembly may satisfy the following relation: (c23/l2)<<(c13/l1), where: l1 denotes the fluid-contacted length of the first surface measured along the first surface in the direction between the opening for receiving fluid and the second surface, l2 denotes a dimension along the third surface measured from the second surface to the end of the device furthest from the opening for receiving fluid, c1 denotes the gap between the body surface and the first surface, and c2 denotes the gap between the body surface and the third surface.
The disclosed embodiments further describe a method for loading fluid, into one or more nozzles of a nozzle-bearing body, using the above-described device, where the nozzle-bearing body has a body surface defining one or more orifices for receiving fluid into the one or more nozzles. While the device is held in the working configuration, proximate to the nozzle-bearing body such that the second member protrudes toward the body surface, and the first surface of the first member and the body surface form a pocket having an opening for receiving the fluid, the method comprises: supplying the fluid into the pocket via the opening, and moving the nozzle-bearing body relative to the device in a direction from the opening toward the second surface while maintaining a gap formed between the first surface and the body surface and a gap formed between the third surface and the body surface substantially constant to load the fluid from the pocket into the one or more nozzles.
The device and the nozzle-bearing body may satisfy the following relation: c1>>3Vn/An, where: c1 denotes the gap between the body surface and the first surface, 1/An refers to the number of nozzles per unit area in the region of the nozzle bearing body opposite the fluid filled region of the first surface, and Vn denotes a desired volume of a fluid for loading into a fluid-contacted nozzle.
The device and the nozzle-bearing body may satisfy the following relation: c2<cp, where: cp denotes an extent to which the third surface protrudes from the first surface, and c2 denotes the gap formed between the body surface and the third surface.
The device and the nozzle-bearing body may satisfy the following relation c2<<cp.
The device and the nozzle-bearing body may satisfy the following relation: (c23/l2)<<(c13/l1), where: l1 denotes a fluid-contacted length of the first surface measured along the first surface in the direction between the opening for receiving fluid and the second surface, l2 denotes a dimension along the third surface measured from the second surface to the end of the device furthest from the opening for receiving fluid, c1 denotes the gap between the body surface and the first surface, and c2 denotes the gap between the body surface and the third surface.
At least one part of the device may be made from a thermally conductive material, and the method may further comprise: maintaining the at least one part at a controlled temperature in a range of ambient to 250 centigrade while loading the fluid into the one or more nozzles.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate disclosed embodiments and, together with the description, serve to explain the disclosed embodiments. In the drawings:
In view of the above-mentioned and other shortcomings and problems with existing systems, the present disclosure describes more effective and efficient techniques for loading fluid(s) into nozzle(s) of a nozzle-bearing body that are suitable for loading fluids of various viscosities. In particular, a new type of a device is disclosed for loading a wide variety of fluids or liquids (including but not limited to pure liquids, solutions, suspensions, emulsions) into nozzle(s) of a nozzle-bearing body. Corresponding assembly and method are also disclosed. Advantageously, the disclosed device may be used with fluids having a wide range of rheological properties, including non-Newtonian viscous properties, and including fluids of viscosity greater than 100·10−3 Pa·s. This new device finds practical application, among others, to non-contact forms of printing, such as the non-contact form of printing described in patent application WO 2017/141034 A1, filed on 15 Feb. 2017, the entire content of which is hereby incorporated by reference, and other uses.
According to an aspect of the present disclosure, there is provided a device for loading fluid into one or more nozzles of a nozzle-bearing body when the device is assembled into a working configuration with the nozzle-bearing body, the nozzle-bearing body having a body surface defining one or more orifices for receiving fluid into the one or more nozzles, the device comprising: a first member having a first surface; and a second member protruding from the first member, the second member having a second surface and a third surface, the second surface extending from the first surface at an interior angle in a range of 20 degrees to 160 degrees, wherein the first surface is shaped to substantially complement the shape of the body surface, and a tangent to the third surface, in a region of the third surface proximate to where the second surface meets the third surface, is substantially parallel to a tangent to the first surface, in a region of the first surface where the first surface meets the second surface, when the device is in the working configuration.
Thus, when the above device is in the working configuration, a gap (‘opening’) for receiving fluid is formed between the body surface and the first surface at the end of the first member that is most distant from the second member. Further, when the device is in the working configuration, a zone for receiving the fluid is formed between the first surface and the second surface for receiving the fluid when the device. Within this zone, the above device generates higher fluid pressures than are those generated by the assembly of
The third surface may be configured to conform to the shape of the body surface of the nozzle-bearing body when the device is in the working configuration and not to complement or substantially complement the shape of the body surface of the nozzle-bearing body when the device is outside the working configuration. This allows greater freedom of choice of material for the second member, in particular the ability to choose more highly conformable materials than would otherwise be possible.
The interior angle may be in a range of 60 degrees to 120 degrees.
The interior angle may be in a range of 80 degrees to 100 degrees.
The interior angle may be 90 degrees or about 90 degrees.
From the lower end of the degree range, an increase of the angle to at least 60, and more so to at least 80 degrees, advantageously helps to prevent formation of a region of stagnant fluid between the first surface and the second surface. Thus, potential clogging up of the device due to the stagnant fluid drying out between uses of the device can be prevented. From the higher end of the degree range, a decrease of the angle to at least 120 degrees, and more so to at least 100 degrees advantageously improves consistency of the nozzle-filling volume or depth. An interior angle of about 90 degrees beneficially balances the above advantages.
The device may further comprise a third member connected to the first member and the second member, the third member having a fourth surface configured to face the body surface when the device is in the working configuration; and a fourth member connected to the first member and the second member opposite the third member, the fourth member having a fifth surface configured to face the body surface when the device is in the working configuration, wherein the third member, the fourth member, the first surface, and the second surface together form a pocket in the device for receiving the fluid when the device is in the working configuration, and wherein at least a portion of the fourth surface and at least a portion of the fifth surface extend from the opposite sides of the third surface to form with the third surface a single surface configured to conform to the body surface when the device is in the working configuration.
This configuration advantageously decreases loss of the fluid from the sides of the device as the nozzle-bearing body is being moved relative to the device, as well as facilitates a consistent fluid pressure across the fluid-loading width of the device, thereby improving consistency of the filling depth of the nozzles.
The third member and the fourth member may be integral with the first member and/or the second member. This advantageously simplifies the device, as well as reduces manufacturing costs.
The device may further comprise: a fifth member having a sixth surface extending from the first surface, opposite where the first surface meets the second surface, wherein an angle formed by the sixth surface and the first surface is in a range of 185 to 275 degrees, and wherein the fifth member is configured to form a funnel between the sixth surface of the fifth member and the body surface of the nozzle-bearing body for collecting the fluid when the device is in the working configuration.
This configuration advantageously allows any excess of the supplied fluid to be collected before the fluid enters the opening, thereby preventing overflowing of the device with the fluid, as well as decreasing loss of the fluid.
The angle formed by the sixth surface and the first surface may be in a range of 200 degrees to 250 degrees. For a given desired volume for collecting the excess fluid to prevent the device overflow, an angle in this range balances the relation between the length of the fifth member and how far it protrudes or extends away from the first member, thereby advantageously allowing to reduce the overall compactness of the device.
The device may further comprise a first end member and a second end member positioned at the opposite sides of the device, wherein: the first end member has a seventh surface configured to conform to the shape of the body surface when the device is in the working configuration, the second end member has an eighth surface configured to conform to the shape of the body surface when the device is in the working configuration, and the seventh surface and the eighth surface comprise respective surface portions aligned with the third surface of the second member, thereby forming an extended surface including the third surface and configured to conform to the body surface when the device is in the working configuration.
This configuration advantageously helps to prevent fluid from flowing out from the ends of the device as well as to stabilise the loading pressure across the fluid-loading width of the device so that the nozzle filling process is similar across the fluid-loading width of the device.
When a device for loading fluid, in any of its configurations as described in this disclosure, is to be used with a planar nozzle-bearing body, the first surface may be planar (thereby configured to complement the shape of the body surface of the nozzle-bearing body) such that the first surface is positionable to be substantially parallel to the planar surface of the nozzle-bearing body and to define an opening with the surface of the nozzle-bearing body for receiving the fluid when the device is in the working configuration being held proximate to the nozzle-bearing body with the second member protruding toward the planar surface of the nozzle-bearing body.
The second surface may be substantially perpendicular to the first surface in a region where the second surface meets the first surface and substantially perpendicular to the third surface in a region where the second surface meets the third surface. In this manner, the consistency of the filling depth of nozzles as the fluid passes from the opening toward the protrusion of the device (the second member) could be advantageously improved under a wide variety of conditions.
When the device for loading fluid, in any of its configurations as described in this disclosure, is to be used with a cylindrical nozzle-bearing body, the first surface may have a cylindrical curvature such that the first surface is positionable to be substantially concentric with the cylindrical body surface (the first surface thereby configured to complement the shape of the body surface) and to define an opening with the cylindrical body surface of the nozzle-bearing body for receiving the fluid when the device is in the working configuration being held proximate to the nozzle-bearing body with the second member protruding toward the cylindrical body surface of the nozzle-bearing body.
The second surface may be substantially perpendicular to the tangent to the first surface in a region where the second surface meets the first surface and substantially perpendicular to the tangent to the third surface in a region where the second surface contacts the third surface. In this manner, the consistency of the filling depth of nozzles as the fluid passes from the opening toward the second surface could be advantageously improved under a wide variety of conditions.
Dimension cp denotes the extent to which the third surface protrudes from the first surface. Dimension l1 is a fluid-contacted length of the first surface measured along the first surface in the direction between the opening for receiving fluid and the second surface when the device is in the working configuration and operated to load fluid into the one or more nozzles. A ratio between dimension cp, and l1 may satisfy the relation: l1/cp>1, and optionally l1/cp>>1. These conditions, in practice, advantageously help to establish consistent fluid ‘filling’ of the device for a wide variety of fluids and operating conditions.
The first member may be made of an engineering material, such as aluminium, brass, stainless steel, polyether ether ketone (PEEK), polytetrafluoroethylene (PTFE), nylon, carbon fibre composite, polyimide, or ultra-high molecular weight polyethylene (UHMWPE).
The second member may be made of a non-abrasive material, such as PTFE, UHMWPE, or nylon. This advantageously reduces damage and wear and tear on the nozzle-bearing body, particularly wear and tear that otherwise could be caused by a non-lubricated contact between the third surface of the device and the body surface of the nozzle-bearing body while the device and the nozzle-bearing body are in the working configuration.
Each portion of the device that is configured to be pressed against the body surface of the nozzle-bearing body while device is in the working configuration may be made of a non-abrasive material, such as polytetrafluoroethylene (PTFE), nylon, or ultra-high molecular weight polyethylene (UHMWPE). This advantageously further reduces damage and wear and tear on the nozzle-bearing body, particularly wear and tear that otherwise could be caused by a non-lubricated contact between those portions of the device and the body surface of the nozzle-bearing body due to its motion relative to the device while the device and the nozzle-bearing body are in the working configuration.
The first member and the second member, and optionally also the third member and fourth member and/or the end members, and further optionally also the fifth member may form a unitary body of the device. This advantageously simplifies device assembly and can improve device mechanical integrity.
All members of the device may form the unitary body having a pocket for receiving fluid in the working configuration, the pocket being defined at least by the first surface and the second surface.
The first member and the second member may be separate parts joined together in the device. This advantageously allows for replacement of the second member with another second member, for example, to achieve different dimensions for the device (particularly different dimensions l1, and cp and consequently adjust the volume of fluid loaded by the device into nozzles), or simply due to wear and tear experienced by the second member, as well as for use of different materials for the first and second members, e.g., a stiffer material for the first member than for the second member.
The first member and the second member may be made of different materials.
Any, at least one, or all of the first member, the second member, the third member, the fourth member and the fifth member and/or the end members may be made of a material having low chemical reactivity. This advantageously helps to prevent chemical reaction between the surface of the nozzle-bearing body and the device, thus prolonging the working life of the device, as well as to prevent contamination of the fluid.
The end members may be made of a non-abrasive material, such as polytetrafluoroethylene (PTFE), UHMWPE, or nylon. This helps to improve the seal between end members and the nozzle-bearing body.
According to another aspect of the present disclosure, there is provided an assembly for loading fluid, the assembly comprising: a nozzle-bearing body having a body surface defining one or more orifices for receiving fluid into the one or more nozzles; and the device for loading the fluid as described in any of the preceding paragraphs of this disclosure, the device and the nozzle-bearing body assembled into a working configuration in which the device is held proximate to (e.g., the third surface of the device being pressed, such as mechanically pressed, against the nozzle-bearing body) the nozzle-bearing body such that the second member of the device protrudes toward the body surface of the nozzle-bearing body and the first surface of the device and the body surface of the nozzle-bearing body form an opening for receiving the fluid, wherein, in the working configuration, the nozzle-bearing body is movable relative to the device in a direction from the opening toward the second surface of the device such that a gap formed between the first surface and the body surface and a gap formed between the third surface and the body surface remain substantially constant, thereby allowing the device to at least partially load the one or more nozzles with fluid received via the opening.
The above assembly generates, within the pocket, higher fluid pressures than are generated by the assembly of
According to another aspect of the present disclosure, there is provided a method for loading fluid into one or more nozzles of a nozzle-bearing body using the device for loading fluid as described in any of the preceding paragraphs of this disclosure, the nozzle-bearing body having a body surface defining one or more orifices for receiving fluid into the one or more nozzles, the method comprising: while holding the device in the working configuration, proximate to the nozzle-bearing body such that the second member protrudes toward the body surface of the nozzle-bearing body, and the first surface of the first member and the surface of the nozzle-bearing body form an opening for receiving the fluid: supplying the fluid to the surface of the nozzle-bearing body, and moving the nozzle-bearing body relative to the device in a direction from the opening toward the second surface while maintaining a gap formed between the first surface and the body surface and a gap formed between the third surface and the body surface substantially constant to load the fluid into the one or more nozzles.
In the above-described device, assembly, and method, the following relation may be satisfied: c1>>3Vn/An, where: c1 denotes the gap between the body surface and the first surface, 1/An refers to the number of nozzles per unit area in the region of the nozzle bearing body opposite the fluid filled region of the first surface, and Vn denotes a desired volume of a fluid for loading into a fluid-contacted nozzle. Advantageously, enforcing this relation helps to avoid a starvation condition in which there is too little fluid within the device to fill the nozzles to the desired extent. This in turn helps maintaining the volume of fluid with which the nozzles are loaded with fluid (or filling depth) substantially constant.
In the above-described device, assembly, and method, the following relation may also be satisfied: c2<cp, where: cp denotes an extent to which the third surface protrudes from the first surface, and c2 denotes the gap formed between the body surface and the third surface of the device. This relation advantageously helps to reduce leakage of the fluid through the gap c2 past the device.
Furthermore, the following relation may be satisfied: c2<<cp. This relation advantageously helps to further reduce leakage of the fluid past the device through the gap c2.
In the above-described device, assembly, and method, the following relation may also be satisfied: (c3/l2)<<(c13/l1), where: l1 denotes a fluid-contacted length of the first surface measured along the first surface in the direction between the opening for receiving fluid and the second surface, l2 denotes a dimension along the third surface measured from the second surface to the end of the device furthest from the opening for receiving fluid, c1 denotes the gap between the body surface and the first surface, and c2 denotes the gap between the body surface and the third surface. Advantageously, enforcing of the above relation helps to minimize and prevent leakage of the fluid past the device through the gap c2.
In the above-described device, assembly, and method, the device, its part(s), or at least its first member may be made from a thermally conductive material capable to withstand temperatures up to 250 degrees centigrade, and the device, its part(s), or the at least first member respectively may be maintained at a controlled temperature in a range of ambient to 250 degrees centigrade while loading the fluid into the one or more nozzles. Advantageously, this enables use of the device with materials that become fluid only at elevated temperatures, such as hot melt adhesives.
The technical advantages described above with reference to various features of the assembly similarly are provided by the corresponding features of the above described method.
In the following description, certain aspects and embodiments of the present disclosure will become evident. It should be understood that the disclosure, in its broadest sense, could be practiced without having one or more features of these aspects and embodiments. It should also be understood that these aspects and embodiments are merely exemplary.
The following detailed description refers to the accompanying drawings. Wherever possible, the same reference numbers are used in the drawings and the following description to refer to the same or similar parts. While several illustrative embodiments and aspects are described herein, modifications, adaptations and other implementations are possible. For example, substitutions, additions, or modifications may be made to the components illustrated in the drawings, and the illustrative methods described herein may be modified by substituting, reordering, removing, or adding steps to the disclosed methods. Accordingly, the following detailed description is not limited to the disclosed embodiments, aspects, and examples. Instead, the proper scope is defined by the appended claims.
The present disclosure generally relates to dispensing of flowable materials and describes a device, assembly, and method for loading nozzles of a nozzle-bearing material body with fluid. In the context of this disclosure, the term ‘fluid’ encompasses any flowable material, such as those materials whose constituent parts or sub-volumes are capable of relative motion, and includes, but not limited to, pure liquids, liquid solutions, suspensions, emulsions, gels, waxes, adhesives, hot melt adhesives, varnishes, primers, etchants, etch resists, encapsulants, liquid electronic materials, inks, pigment inks, dye based inks, latex solutions, latex suspensions, chocolate, mayonnaise, ketchup, liquid chocolate, biological fluids such as cell suspensions and pharmaceutical solutions, suspensions, creams, pastes and gels, and other flowable materials.
Throughout this disclosure, a ‘nozzle’ shall be understood to include a conduit that extends between two orifices in the surface or surfaces (often opposing surfaces) of a material body; a ‘nozzle-bearing body’ or simply ‘body’ shall be understood to include a material body in which there is at least one nozzle; and ‘filling’ or ‘loading’ of nozzle(s) shall be understood to include partial filling/loading of the nozzle(s) with fluid or liquid. Throughout this disclosure, ‘substantially parallel’ shall be understood to include small deviations from a parallel relationship of 20 degrees or less, while ‘substantially concentric’ shall be understood to include small deviations from concentricity such that the tangents to the cylindrical surface of the nozzle-bearing body and the upstream surface taken where they meet a common radial vector originating at the axis of the cylindrical material body shall form a small acute angle of 20 degrees or less.
Throughout this disclosure, a surface (area or portion of the surface) ‘complementing’ another surface (area or portion of the surface) or being ‘complementary’ to another surface (area or portion of the surface) shall be understood that such surfaces can be positioned in such a way that they form a uniform gap between them across the full surface area of the smaller of those surfaces, or either of the surfaces if the surfaces are of the same size. Throughout this disclosure, a surface (area or portion of the surface) ‘substantially complementing’ another surface (area or portion of the surface) or being ‘substantially complementary’ to another surface (area or portion of the surface) shall be understood that, such surfaces can be positioned in such a way that any gap formed between them across the full surface area of the smaller of those surfaces, or either of the surfaces if the surfaces are of the same size varies by no more than cp (the extent to which the protruding surface of the device protrudes from first surface of the first member of the device—discussed below in greater detail, for example, with reference to
The device 300 (may also be referred to as a guide, fluid supply guide, filler, fluid filler, loader, or fluid loader) includes two members 310 and 320. The first member 310 (may also be also referred to as a first body part) defines a first surface 316 approximately in the ({circumflex over (x)}, {circumflex over (z)}) plane. The second member 320 (may also be referred to as a second body part) defines a third surface 326 approximately in the ({circumflex over (x)}, {circumflex over (z)}) plane and a second surface 328 (may also be referred to as a protruding surface) approximately in the ({circumflex over (y)}, {circumflex over (z)}) plane. The first and second members 310 and 320 are connected such that the second surface 328 of the second member protrudes or extends from the first surface 316 of the first member 310. The second surface 328 and the first surface 316 form an interior angle θ.
Throughout this disclosure, the first and third surfaces may also be referred to as the upstream and downstream surfaces respectively. This reflects positioning of the surfaces in relation to the supply of fluid onto the surface of the nozzle-bearing body when the device and the nozzle-bearing body are assembled into a working configuration (discussed below in greater detail). Therefore, the terms ‘first surface’ and ‘upstream surface’ may be used interchangeably in relation to any of variations of the device for loading fluid described in this disclosure. Similarly, the terms ‘third surface’ and ‘downstream surface’ may be used interchangeably in relation to any of variations of the device for loading fluid described in this disclosure.
In
In the device 300, the upstream surface 316 and the downstream surface 326 are substantially parallel. Further, the upstream surface 316 is also configured to be substantially parallel to the body surface of a planar nozzle-bearing body when the device 300 and the nozzle-bearing body (not shown in
In the working configuration, the device 300 is positioned and held proximate to the nozzle-bearing body (e.g., mechanically pressed against the nozzle-bearing body) such that the second member 320 protrudes toward the body surface of the nozzle-bearing body. In such a configuration, the upstream surface 316 of the device 300 and the body surface of the nozzle-bearing body form an opening 330 for receiving fluid to be loaded into the nozzles of the nozzle-bearing body via respective orifices. A small gap may also be formed between the downstream surface 326 and the body surface of the nozzle-bearing body. In such configurations, this gap ends in a terminal gap 340 at the furthest end of the downstream surface 326 from the opening 330. While the working configuration is in use, at least the upstream surface 316, the protruding surface 328, and the body surface of the nozzle-bearing body come in contact with the fluid. In most practical configurations a small gap is formed between the downstream surface 326 and the body surface of the nozzle-bearing body and downstream surface 326 also comes into contact with the fluid.
The device 300 has fluid-loading width z, which is measured in direction {circumflex over (z)} along the first member 310.The height (may also be referred to as ‘protrusion height’) cp of the second member 320—the maximum extension of the protruding surface 328 perpendicular to the upstream surface 316—is measured in direction {circumflex over (y)}. The length of the downstream surface 326, l2, is measured in direction {circumflex over (x)}. The length of the upstream surface 316 that is contacted by fluid, l1, while the device 300 is in use in the working configuration, is also measured in direction {circumflex over (x)}. The particular device 300 of
In this disclosure, for simplicity but without limitation, only the case in which the entire length of the upstream surface is contacted by fluid is described in detail. Therefore in
As shown in
The first and second members 310 and 320 may be made of the same or different materials. For example, the second member 320 may be made of a non-abrasive material, such as polytetrafluoroethylene (PTFE), nylon, or ultra-high molecular weight polyethylene (UHMWPE). Using a non-abrasive material reduces wear and tear on the body surface of the nozzle-bearing body, thereby extending its usable life.
The first member and/or the second member may be made of a material having low chemical reactivity. Using materials having low chemical reactivity helps to prevent chemical reaction between the surface of the nozzle-bearing body and the device, thus prolonging the working life of the device, as well as to prevent contamination of the fluid.
The first member may be made of an engineering material, such as aluminium, brass, stainless steel, polytetrafluoroethylene (PTFE), polyether ether ketone (PEEK), nylon, carbon fibre composite, ultra-high molecular weight polyethylene (UHMWPE), or polyimide.
In some example implementations, the first member 310 and second member 320 form a unitary body, made of the same material, such as polytetrafluoroethylene (PTFE).
As explained above, the protruding surface of the second member, such as the protruding surface 328 in
In some example implementations, the interior angle is in the range from 60 degrees to 120 degrees, or in the range from 80 degrees to 100 degrees. Starting from the lower end of the range, increasing the angle to at least 60 degrees, or to at least 80 degrees helps to prevent formation of a region of stagnant fluid between the upstream surface of the first member and the protruding surface of the second member. If left unattended, such stagnant fluid may dry out and clog up the device. Starting from the upper end of the degree range, by decreasing the angle to at least 120 degrees, or to at least 100 degrees, a more constant nozzle-filling volume/depth can be achieved. An angle of about 90 degrees, such as in a profile 400a, balances these considerations.
The L-shaped cross-sectional profile 400a is a cross-sectional profile of the device 300 shown in
Example profiles 400b to 400f are variations on the L-shaped profile 400a. For example, the profile 400b is formed by the upstream surface of the first member which curves away from the protruding surface of the second member. The downstream surface of the second member is concentric to the upstream surface of the first member. This geometry is particularly useful for filling nozzle-bearing bodies in the form of a cylindrical shell from the interior of the cylindrical shell.
The profile 400c is formed by the upstream surface of the first member leaning away from the protruding surface of the second member, where the interior and protruding surfaces form an interior angle θ of about 100 degrees. This geometry is also useful for filling planar nozzle-bearing bodies.
The profile 400d is formed by the upstream surface of the first member, curving toward the protruding surface of the second member, and the protruding surface of the second member. The downstream surface of the second member is substantially concentric to the upstream surface of the first member. This geometry is particularly useful for filling nozzle-bearing bodies having the form of a cylindrical shell from the exterior of the cylindrical shell
Similar to the profile 400c, the profile 400e is formed by the upstream surface of the first member leaning away from the protruding surface of the second member. The interior and protruding surfaces form an interior angle θ of about 100 degrees. However, unlike in 400c where the first member has the same thickness throughout, in 400d, the thickness of the first member decreases in the direction away from the second member. The cross-section of the first member therefore has a trapezoidal shape. Furthermore, unlike in 400c, where the downstream surface of the second member is substantially parallel to the upstream surface of the first member, in 400e, the downstream surface of the second member is parallel to the upstream surface of the first member. This geometry is also useful for filling planar nozzle-bearing bodies.
In the cross-sectional profile 400f, the second member has a step and an incline. Such a shape creates two interior angles between the first and second members. The first interior angle is formed between the upstream surface of the first member and the incline portion of the projecting surface of the second member, i.e., angle θ1. The second angle is formed between the upstream surface of the first member and the step portion of the projecting surface of the second member, i.e., angle θ2. Both such angles are in the range from 20 degrees to 160 degrees.
The same principle to increasing the lower end of the degree range and decreasing the higher end of the degree range, as discussed above, applies to each of the multiple interior angles formed between the first and second members due to, for example, a complex shape of second member such as shown in the profile 400f. The geometry of the profile 400f is also useful for filling planar nozzle-bearing bodies.
As explained above and can be seen in
With reference to cross-sectional profiles 400b and 400d, satisfactory operation can be achieved when the upstream surface of the first member is substantially concentric with the cylindrical surface of a nozzle-bearing body. In one example working configuration the device having for example profile 400d is positioned exterior and proximate to the outer surface of a cylindrical nozzle-bearing body taking the form of a cylindrical shell whose thickness is penetrated by nozzles from its interior to its downstream surface. In this configuration the upstream surface of the device may be arranged to have concave cylindrical curvature that complements the convex cylindrical curvature of the proximate nozzle-bearing outer surface of the cylindrical shell. In a second example working configuration the device having for example profile 400b is positioned interior and proximate to the inner surface of a cylindrical nozzle-bearing body taking the form of a cylindrical shell whose thickness is penetrated by nozzles from its interior to its exterior surface. In this configuration the upstream surface of the device may be arranged to have convex cylindrical curvature that complements the concave cylindrical curvature of the proximate nozzle-bearing inner surface of the cylindrical shell.
In the context of this disclosure, ‘substantially concentric’ shall be understood to include small deviations from concentricity such that the tangents to the cylindrical surface of the nozzle-bearing body and the upstream surface taken where they meet a common radial vector originating at the axis of the cylindrical material body shall form a small acute angle (less than or equal to 20 degrees). Similarly, ‘substantially parallel’ shall be understood to include small deviations from parallelism such that the planar surface of the upstream body and the planar surface of the nozzle-bearing body shall form a small acute angle (less than or equal to 20 degrees). Thus, for example, with reference to
Further, satisfactory operation can also be achieved using a device whose downstream surface of the second member is not parallel, substantially parallel, concentric, or substantially concentric to the upstream surface of the first member while the device is not in use. In this scenario, to achieve satisfactory operation of the device, the downstream surface is configured to conform to the surface of the nozzle-bearing body such that, when the device and the nozzle-bearing body are assembled into the working configuration, the downstream surface of the second member becomes parallel, substantially parallel, concentric, or substantially concentric to the surface of the nozzle bearing body, for example, due to the device being pressed against the surface of the nozzle bearing body.
The plate 570 has width zp in the {circumflex over (z)} direction, which may be the same as the fluid-loading width z of the device 300 or wider than the fluid-loading width z of the device 300. In the latter scenario, the fluid-loading width z of device 300 should be sufficiently wide to accommodate the width of the portion of the plate containing nozzles that have been selected for loading with fluid. The plate width zp may also be narrower than the fluid-loading width z of the device 300, although in this scenario, there can be considerable loss of fluid while loading the nozzles.
Generally, the device 300 may be used to load or fill (including partially load or fill) fluid into the nozzle(s) 576 via the orifices 578 in the surface 574 of the plate 570 by arranging for:
In the example of
In
respectively. Those skilled in the art will appreciate that analogous relations apply to the case of the cylindrical geometry discussed below, for example with reference to
As shown in
Translation of the plate 570 in direction {circumflex over (x)}, shown by arrow 580, provides relative motion between the plate 570 and the stationary device 300. This motion transforms the supplied fluid 564 into a fluid layer on the upper surface 574 of the plate 570 and carries the fluid 564 to the device 300. In the area between the point at which the plate 570 receives the fluid 564 and the entrance 330 into the device 300, the surfaces 566 and 568 of the fluid 564 contact the ambient atmosphere. Therefore, in this region the fluid is at closely ambient pressure, and thus only gravitational forces and surface energy differences between the fluid 564 and material surface of nozzles 576 provide forces that encourage fluid 564 to enter the nozzles 576 through the orifices 578 in the upper surface 574 of the plate 570. For fluids of high viscosity (typically 100.10−3 Pa·s to 1000.10−3 Pa·s), such as industrial coatings, paints, toothpaste, hot melt glue, and epoxy resins, and nozzles having cross-sectional dimensions between 0.1 mm and 2 mm, these forces are generally too weak to cause significant filling of the nozzles 576 in timescales of 0.1 second or less, which timescales are typical in production processes for the deposition of fluids upon substrates.
The dimensions cp, l1 and c2 are chosen such that when the translation brings the supplied fluid 564 through the entrance 330, the viscous forces opposing fluid flow in the nozzles and in the gap c2 enable fluid 564 to be supplied at a rate sufficient to fill the gap c1. Under these conditions, the fluid 564 is in contact with the upper body surface 574 of the plate 570, the upstream surface 316 along the length l1, and the protruding surface 328 of the device 300. Due to the presence of the protruding surface 328, the viscosity of the fluid 564, and the relative motion between the upstream surface 316 of the device 300 and the upper surface 574 of the plate 570, the fluid 564 experiences shear forces that cause the fluid pressure within the gap c1 to increase in the direction from the entrance 330 toward the protruding surface 328. In general, the fluid 564 will also be in contact with the downstream surface 326 in the gap c2 along length l2 and in this case the fluid pressure decreases in the gap c2 in the direction from the protruding surface 328 to the terminal gap 340, whereupon any exiting film of fluid again experiences ambient pressure.
The fluid pressure generally reaches a maximum near the point where the upstream surface 316 ends and the protruding surface 328 begins. Due to the flow into the nozzles 576, the pressure profile will be somewhat perturbed, and the maximum may not be precisely at the point where the upstream surface 316 meets the protruding surface 328. Nonetheless, there is a profile in direction {circumflex over (x)} of positive pressure difference between the fluid 564 within the device 300 and the ambient pressure that exists immediately outside the fluid menisci in the nozzles 576. This pressure profile causes the fluid 564 to flow into the nozzles 576, displacing those menisci to load the nozzles with fluid, as the nozzles 576 translate past the device 300.
Some of the fluid 564 may flow out through the terminal gap 340. It is however generally desirable to keep to a practical minimum such discharge of fluid through the terminal gap 340 since this ‘excess fluid’ does not carry the pattern of nozzles that is ultimately desired to be deposited upon a final substrate.
The dimensions l1, l2, and cp, and the ‘close proximity’ gap c2 in the working configuration of the device for loading fluid, such as the device 300, may be selected to provide profiles of fluid pressure suitable for filling nozzles that extend between orifices in opposing surfaces of a material body. In particular, these dimensions may be chosen to meet the following conditions:
For this geometry, cylindrical coordinates (r, ϕ, z) are used with corresponding unit vectors in the directions of increasing radial distance r, circumferential angle ϕ and axial distance z shown as {circumflex over (r)}, {circumflex over (ϕ)}, {circumflex over (z)} respectively. The cylindrical body 770 has width zc in the {circumflex over (z)} direction, which may be the same as the fluid-loading width z of the device 702 measured axially or wider than the fluid-loading width z of the device 702 measured axially. In the latter scenario, the fluid-loading width z of the device 702 should be sufficient to accommodate the width of the portion of the nozzle-bearing surface 774 containing nozzles 776 that have been selected for loading with fluid. The cylinder width z, may also be narrower than the fluid-loading width z of the device 702, although in this scenario, there may be considerable loss of fluid while loading the nozzles 776.
The device 702 is generally similar to the device 300 and is subject to the similar principles, although its shapes and dimension are adapted to cooperate with the cylindrical nozzle-bearing body 770 as explained below. In particular, the device 702 may be used to load, including partially load, fluid into nozzles 776 that terminate in orifices 778 in a cylindrical body surface 774 of the body 770 by arranging for:
The upstream surface 716 and the downstream surface 726 are, in this example, concentric with the outer cylindrical surface 774 of the cylindrical body 770. As shown in
As shown in
Rotation of the body 770 in circumferential direction {circumflex over (ϕ)} shown at 780 provides relative motion between the outer cylindrical surface 774 and the stationary device 702. This motion transforms the supplied fluid into a fluid layer on the outer cylindrical surface 774 and carries the fluid 764 to the device 702.
Similar to the plate scenario described with reference to
The dimensions cp, l1 and c2 are chosen such that when the rotation 780 of the cylindrical body 770 brings the supplied fluid 764 through the entrance 730, the viscous forces opposing fluid flow in the nozzles and in the gap c2 enable fluid 764 to be supplied at a rate sufficient to fill the gap c2. Under these conditions, the fluid 764 is in contact with the upper body surface 774 of the cylindrical body 770, the upstream surface 716 along the length l1, and the protruding surface 728 of the device 702. Due to the presence of the protruding surface 728, the viscosity of the fluid 764, and the relative rotational motion between the upstream surface 716 of the device 702 and the upper surface 774 of the cylindrical body 770, the fluid 764 experiences shear forces that cause the fluid pressure within the gap c1 to increase in the direction from the entrance 730 to the protruding surface 728. In general, the fluid 764 will also be in contact with the downstream surface 726 in the gap c2 along length l2 and in this case the fluid pressure within the gap c2 decreases in the direction from the protruding surface 728 to the terminal gap 740, whereupon any exiting film of fluid again experiences ambient pressure.
The fluid pressure generally reaches a maximum near the point where the upstream surface 716 ends and the protruding surface 728 begins. Due to the flow into the nozzles 776, the pressure profile will be somewhat perturbed, and the maximum may not be precisely at the point where the upstream surface 716 meets the protruding surface 728. Nonetheless, there is a profile in the circumferential direction {circumflex over (ϕ)} of positive pressure difference between the fluid 764 within the device 702 and the ambient pressure that exists immediately outside the fluid menisci in the nozzles 776. This pressure profile causes the fluid 764 to flow into the nozzles 776, displacing those menisci to load the nozzles with fluid, as the nozzles 776 are transported past the device 702.
Some of the fluid 764 may flow out through the terminal gap 840. It is however generally desirable to keep to a practical minimum such discharge of fluid through the terminal gap 840 since this ‘excess fluid’ does not carry the pattern of nozzles that is ultimately desired to be deposited upon a final substrate.
Moving onto design and operating conditions to provide effective filling of nozzles while minimising the flow of ‘excess liquid’ through the terminal gap, these are described for the cylindrical geometry described with reference to
The dimensions l1, l2, and cp, and the ‘close proximity’ gap c2 in the working configuration of the device for loading fluid, such as the device 702, are selected to fill (including partially fill) nozzles that extend between orifices in opposing surfaces of a material body with the desired volume of fluid. In particular, these dimensions may be chosen to:
With reference to
For example, if c2 is selected such that c2<0.5c1, i.e., c1>2c2 then, since c1=c2+cp, c2 satisfies the condition c2<cp along circumferential arc length l2 and, possibly, c2<<cp. The condition c2<cp defines the ‘close proximity’ positioning of the device to the nozzle-bearing body in the working configuration as described throughout this disclosure. Satisfying this condition helps to meet conditions (ii) and (iii) above.
An example practical implementation for meeting the above conditions in the assembly 700 includes, in the absence of fluid supply, positioning the device to press the downstream surface 726 of the device 702 against the body surface 774 of the nozzle-bearing body 770 and holding the device 702 in this position. For example, the device can be mechanically pressed against the body surface 774, such as spring held. With no fluid supplied, c2=0. In this implementation, once the fluid 764 is supplied, c2 may rise above 0 due only to a very thin lubricating film of fluid between the downstream surface 726 and the body surface 774. The condition c2<cp and, furthermore, the condition c2<<cp, are therefore easily met, the latter ensuring that the condition c2<<c1 is met. In this manner, both the contribution to nozzle loading past the downstream surface 726 of the second member 720 and to excess flow of fluid through the terminal gap 840 is reduced.
More generally and as discussed above, the upstream surface 716 and the downstream surface 726 do not need to be perfectly concentric with the fluid-contacted outer surface 774 of the cylindrical shell 770. Rather, they need to be ‘substantially concentric’ as defined above. In such cases, satisfying the condition c2<cp everywhere along the circumferential arc length l2 ensures the device 702 is in ‘close proximity’ to the nozzle-bearing body 770.
As described above, the fluid pressure within the gap c1 is rising along the fluid-contacted circumferential arc length l1 (in the direction from the entrance 730 toward the protruding surface 728) across the fluid-loading width z of the device. As the upstream surface 716 and the body surface 774 substantially complement each other and oppose each other in the working configuration, a fluid-contacted area of the nozzle-bearing body over which the fluid pressure rises, when the device is in use, Ad, can be approximated as Ad≈l1z. Let the pattern of nozzle orifices on the surface of the nozzle-bearing body be such that there are n nozzles within that fluid-contacted area Ad. Then, the area of the body surface over which the fluid pressure rises (i.e. the area of the body surface complementing the fluid-contacted area of the upstream surface along the fluid-contacted circumferential arc length) per fluid-contacted nozzle is Ad/n. This area is denoted as An, i.e., An=Ad/n≈l1z/n. Consequently 1/An is the number of nozzles per unit area in the region of the nozzle bearing body opposite the fluid filled region of the first surface.
In many practical applications n>>1 so that An<<Ad. In such cases it is particularly advantageous to operate the assembly 700 under the following further conditions:
It has been found that, if values of cp, and l1 meeting conditions (iii), (iv) and (v) above can be found that provide a ratio l1/cp>1 and preferably l1/cp>>1 then the present device can provide consistent fluid ‘filling’ for a wide variety of fluids and operating conditions.
One experimental device according to the present disclosure was created to load fluid into the nozzles of a nozzle-bearing body in the form of a cylindrical shell, via orifices in the outer surface of the shell. The shell thickness was 2 mm and the nozzles were arranged in an array pattern penetrated through its thickness. Each nozzle length was therefore 2 mm and each nozzle had a circular cross-section diameter dn=0.5 mm throughout that length. Each nozzle volume was therefore able to accommodate a maximum volume of 0.39 mm3 without overfilling.
The device was designed to load a volume Vn=0.33 mm3 of fluid into that array of nozzles, which were spaced apart in a regular pattern such that An=6.9 mm2 . Consequently condition (iii) above required c1>>3Vn/An=143 μm and condition (iv) above required l1≈7.7c1. l1 and c1 were selected correspondingly as l1=10 mm and c1=1.3 mm. To meet the stricter of the relations in (v) above, namely c2<<cp, cp has been selected as cp=1.2 mm, giving c2=c1−cp=100 μm<<cp as required. The desirable ratio l1/cp>>1 was also therefore met. The value of l2 was then chosen to satisfy (vi) using the now-determined values of c1, c2, and l1, requiring l2>>5 μm. l2 was selected as l2=3.1 mm, meeting this condition.
The device was constructed with the overall geometry as described with reference to
As in the above example, it should be noted that if the condition c2<<c1 is met, then it is generally not necessary for l2>l1 in order to satisfy the condition (chu 3/l2)<<(c13/l1). In practical implementation, it is often convenient for the device to be designed such that l2<l1.
Under the above conditions (i)-(vi), the filling/loading of nozzles with fluid during their passage past length l2 of the device 702 becomes much less than their filling/loading during their passage past length l1. Further, under these conditions and for a wide range of liquid viscosities, the total volume of fluid that enters the nozzles is substantially constant. This means that the total volume entering each nozzle becomes:
This in turn means that the ‘fill volume’ Vn of the nozzles can be simply adjusted by the dimensions l1 and cp of just the device itself, with little sensitivity to many other parameters, including the precise value of gap c2. This gives particular benefits when printing according to the techniques disclosed in WO 2017/141034 A1 since it allows the bolus volume of fluid ultimately deposited from each nozzle onto final substrates to be substantially constant despite viscosity changes of the fluid due, for example, to variations in operating temperature, and substantially constant irrespective of precise value of operating gap c2. In the case of planar geometry, such as the assembly described with reference to
The first and second side members 903 and 907 respectively have a fourth surface 905 and a fifth surface 909. When the device is in use, in the working configuration, the surfaces 905 and 909 face the body surface of the nozzle-bearing body. As shown in
Using the side members configuration of the device 900 in a device for loading fluid facilitates decreased loss of the fluid from the sides of the device as the device is moved relative to the nozzle-bearing body, as well as facilitates a consistent fluid pressure across the fluid-loading width z of the device, thereby improving consistency of the filling depth/volume of the nozzles.
The angle Δ formed between the upstream surface 1116 and the funnel surface 1117 is in a range from 185 degrees to 265 degrees, preferably in a range from 200 to 250 degrees, such that, when the device is assembled into a working configuration with the nozzle bearing body, a funnel is formed between the funnel surface 1117 of the device 1100 and the body surface of the nozzle bearing body for collecting excess fluid supplied to the nozzle-bearing body. This funnel can be seen in
With reference to
However, in experimental implementations, for devices in which that the fluid-contacted length l1 was much smaller than the distance between nozzles and an end of the fluid-loading width z of the device this leakage flow did not produce unacceptable variations in the volume with which nozzles in the nozzle-bearing body were filled across the fluid-loading width z. Indeed, this condition may be obtained, and a practical device thereby result, even when the fluid-loading width of the device is the same as the total width of the device (i.e. when surfaces 1103 and 1107 and side surfaces 1131 and 1132 are absent). In such cases, the funnel formed between such a device and the body surface of the nozzle-bearing body still facilitates prevention of overflow of the device with fluid supplied to the nozzle-bearing body.
For example,
Returning to
Alternatively or additionally, the device shown in
Similar to the device 1100 of
Similar to the device 1100 of
When the device for loading fluid has a configuration which includes side plates or end members, e.g., side plates 1650 of the device 1600, such side plates/members can be attached to the body of the device permanently, e.g., glued or bonded to the body of the device, or mounted detachably, e.g., bolted on or screwed on. In the latter case, the end members (such as the side plates 1650) can be replaced for different applications and/or different operating conditions (e.g., depending on a temperature at which the device is used to load fluid into nozzles of the nozzle-bearing body), as well as their respective surfaces (e.g., surfaces 1652) wear or become damaged.
In the variation of the device for loading fluid depicted in
Other types of fastening means, however, can be used, e.g., bolts, dowels and clamps, spring pin(s), etc. Good fit and alignment between the end members and the body of the device will improve leakage prevention from the device provided by the end members.
As stated above, in some example devices, the end members instead can be permanently attached to the body of the device. The methods for permanent attachment include, but not limited to, for example, gluing and bonding. Gluing involves fixing two components together using a separate adhesive. Examples of adhesives that could be used for gluing two components, such as the end member and the body of the device for loading fluid include epoxy-based adhesives and cyano-acrylate adhesives.
Unlike gluing, bonding does not use a separate adhesive layer. Rather, when bonding is used to attach the end member to the body of the device, identical materials would typically be used for both components, e.g., polymethyl methacrylate (PMMA) to PMMA, or polytetrafluoroethylene (PTFE) to PTFE. Examples of bonding that could be used to attach an end member to a body of a device for loading fluid include, but not limited to, thermal bonding and solvent bonding.
The following considerations for gluing and bonding materials, among others, may affect what materials are selected to manufacture a particular device for loading fluid:
Generally, the device 1300 is similar to the device 1100 described with reference to
Each surface 1352 includes a surface portion 1354 aligned with a downstream surface 1326 of the device 1300, thereby forming an extended surface including the downstream surface that is configured to conform to the body surface when the device is in the working configuration. Similar to the device 1100 of
The side members 1350 help to prevent fluid from flowing out from the ends of the device 1300, as well as to stabilise the loading pressure across the fluid-loading width z of the device 1300 so that the nozzle filling process is similar across the device 1300.
Although in
Referring back to
Similar to the configuration 700 of
In both configurations, the fluid supply tank 2760 or similar means is positioned with the openings(s) above the pocket 2723 or 2923 formed by the device 1800 and the nozzle-bearing body 2770 or 2900 respectively to deposit fluid 2764 directly into the pocket. The device for loading fluid 2700, 2900 and the fluid supply tank 2760 are stationary. Rotational motion of outer surface of the nozzle-bearing body 2770, 2970 relative to the device enables loading of the nozzles with fluid while the fluid supply tank 2760 replenishes fluid in the pocket 2723, 2923 at a desired rate. The same principles as discussed elsewhere in this application, including
Different applications may require different flow levels. For example, depositing a coating at 10 g/m2 across a width of 200 mm of a nozzle-bearing body at a speed of 0.25 m/s requires 0.5 g/s coating flow rate. Depositing a coating at 40 g/m2 across a width of 200 mm of a nozzle-bearing body at a speed of 1 m/s requires 8 g/s coating flow rate. Assuming an operation of depositing fluid into the pocket formed by the device and the nozzle-bearing body at the same flow level, some device configurations described in this application will reduce fluid leakage from the pocket during the operation of the device to a greater extent than other configurations. For example, in the applications where leakage is undesirable, the device 1100 shown in
The level at which the nozzles of the nozzle-bearing body could be filled using a device for loading fluid, such as the devices described in this application, can be, in certain scenarios, controlled by controlling the flow rate of the fluid provided into the pocket. For example, with reference to
As shown in
On the other hand, for applications where the coating weight needs to be varied, which in turn controlled through the nozzle fill levels, can be achieved by maintaining the meniscus level lower than the level 2090. In such a scenario, the level of the nozzle fill is determined by the rate at which the fluid is fed into the pocket. The meniscus rises within the pocket to a level where the pressure generated in the fluid in the device is such that the rate of fluid flow into the nozzles matches the rate at which fluid is fed into the pocket. The meniscus level then depends on the rate of fluid supply, the dimensions of the device, and the viscosity of the fluid. A further example of maintaining the meniscus below the top of the upstream surface can been seen in
Due to the simplicity of the device 2200, device 2200 is easy to manufacture. Furthermore, the consistent geometry of the recess 2223 leads to a stable meniscus across the length of the recess. However, when assembled with a nozzle-bearing body into a working configuration, such a device does not form a pocket, thereby allowing the fluid to readily spill on both sides the sides of the device while in operation. Nonetheless, the device 2200 could be appropriate for use in a low-flow operation, particularly where fluid spillage is acceptable.
Similar to the geometry of the device 1600, the upstream surface 3016 and protruding surface 3028 define a recess 3023 configured to form a pocket 3025 when the device 3000 is assembled into a working configuration with the nozzle-bearing body 3070. In this example, the recess 3023 is configured to form an inner region 3022 of the pocket 3025, where the pocket 3025 is further defined by a funnel surface 3017 and end members 3050, which form an outer region 3024 of the pocket 3025.
To illustrate the relation of the device 3000 and the body 3070 while in the working configuration, three regions have been identified in
In some cases of using the above described devices and assemblies, it may be advantageous to control the temperature of the device. This may be done for example to maintain a uniform temperature in the loading/filling zone. This may also be done when the material being loaded into the nozzles is in a fluid state at elevated temperatures, e.g., hot melt adhesives. Thus, for example in the case of hot melt adhesives, operating the device at an elevated temperature facilitates the flow of the hot melt adhesive and its loading into the nozzles.
In such cases, the device may be operated at a controlled temperature between ambient and 250 degrees centigrade. For example, the main body of the device could be made of a thermally conductive material, such as aluminium or brass. A practical implementation example includes a device made from brass and heated to 160 degrees centigrade using electrical cartridge heaters using thermocouples to measure and control the operating temperature.
The devices for loading fluid described in this application can be manufactured by means of various manufacturing methods. For example, the device as a whole or its components can be machined out of block(s) of material. Alternatively, or additionally, some or all parts or the device as a whole can be manufactured using extrusion and/or injection molding. 3D printing (FDM) and/or selective laser sintering (SLS) may additionally or alternatively be used to manufacture components of the device for loading fluid or the device as a whole.
Table 1 lists considerations that may affect selection of a particular method for manufacturing a device for loading fluid into a nozzle-bearing body.
Comparing more specifically a device machined from PTFE and a device of the same geometry 3D printed using poly lactic acid (PLA), the following differences can be observed. Firstly, the device machined from PTFE has a smooth surface finish while the device 3D printed using PLA has a textured finish. The resulting textured finish can be controlled in 3D printing. As texture can be used to improve wetting properties of the device, 3D printing could be an advantageous manufacturing method when compared to machining when certain wetting properties are desired.
Secondly, 3D printing allows to achieve a more precise shaping of the device than machining. For example, when the device is machined, the recess formed in the device would typically have curved corners due to the tooling used in machining. This can be corrected, e.g., precise corners can be achieved, if the device is 3D printed.
In the above described devices for loading fluid, any, some, or all of the members of the device or their portions (or parts) may be made of the same or different materials. For example, all portion(s) of the device that are configured to be pressed against the body surface of the nozzle-bearing body while the device is in the working configuration may be made of a non-abrasive material, such as polytetrafluoroethylene (PTFE), nylon, or ultra-high molecular weight polyethylene (UHMWPE). Using a non-abrasive material reduces wear and tear on the body surface of the nozzle-bearing body, thereby extending its usable life.
Further, by using soft material(s) to make this(ese) portion(s) of the device, sealing between the device and the nozzle-bearing can be improved. Soft materials enable the respective portion(s) of the device to conform to the surface of the nozzle-bearing body when the device is pressed against the nozzle-bearing body, thereby improving sealing.
Additionally, by changing geometry of surface(s) of the device that come in contact with the nozzle-bearing body when the device is in the working configuration, sealing between the device and the nozzle-bearing body can be further improved.
In
A downstream surface 31268 of a device 31028 is curved, and thus does not complement the surface of the nozzle-bearing body 3170, which is shaped as a plate, when the device 3102B is outside of the working configuration. However, by pressing the device 31028 against the nozzle-bearing body 3170, the downstream surface 3126B takes a shape conforming to the surface of the nozzle-bearing body 3170 with the force being concentrated in a small region 31058 of the downstream surface 3126B, thereby leading to improved sealing of the downstream surface 31268 with the nozzle-bearing body 3170.
According to a further example, at least those members of the device and/or their portions that, in use, come into contact with fluid and/or the surface of the nozzle bearing body may be made of a material having low chemical reactivity. Using materials having low chemical reactivity helps to prevent chemical reaction between the surface of the nozzle-bearing body and the device, thus prolonging the working life of the device, as well as to prevent contamination of the fluid respectively.
Further, wettability of the inner surfaces of the recess forming the pocket for receiving fluid, such as the upstream and projecting surfaces, could affect performance of the device, and thus selection of materials for such parts. The wettability of a surface, such as of the upstream surface, can be enhanced by surface treatments, including but not limited to corona treating, flame treating, chemical etching, or the application of a thin surface coating to the surface of the part, by e.g., anodization (for aluminium), vapor deposition, or plasma deposition.
For example,
In some example devices, only two materials are used. For example, the bulk of the device could be made from a material having a high surface-energy and high wettability (contact angle less than 90 degrees). This reduces likelihood of air bubbles being formed within the pocket when fluid is delivered into the pocket. The second material could be used to form the surface that comes in contact with the nozzle-bearing body, e.g., the surfaces 1126 and 2526 of the device 2500 in
A device for loading fluid can be configured that the upstream, downstream, and protruding surfaces, some or all, form a continuous surface.
When in a working configuration with a nozzle-bearing body, a device for loading fluid designed according to the techniques described throughout this disclosure advantageously creates a pressure in fluid to be loaded into nozzle(s) of the nozzle-bearing body, and particularly a pressure in the fluid that causes the fluid to be loaded into the nozzle(s). Further, the device designed and operated under the conditions described in this disclosure, allows a pressure to be created in the fluid to load the nozzle(s) to a volume and depth, for a wide range of fluid viscosities, substantially independent of the fluid viscosity over a wide range of fluid viscosities (including, but not limited to, adhesives, hot melt adhesives, chocolate, mayonnaise, ketchup, liquid chocolate, pigment inks, dye-based inks, varnishes, primers, etchants, etch resists, encapsulants, electronic materials, and other fluids), substantially independent of the temperature of the fluid, and substantially independent of the relative speed with which the nozzle-bearing body and device for loading fluid translate past each other, for a wide range of such relative speeds. In printing applications this advantageously ensures that, for a wide variety of fluids and operating conditions, the volume of fluid ultimately deposited from each nozzle onto final substrates to be substantially constant, despite viscosity changes of the fluid due, for example, to variations in operating temperature or the relative speed of motion between the device and the nozzle-bearing surface. Further, the device described in this disclosure and operated as described in this disclosure advantageously facilitates a filling pressure that is uniform across the fluid-contacted width of the nozzle-bearing body, and furthermore is able to prevent the fluid from overflowing the device. This enable application of the disclosed device, method, and assembly in many areas, including but not limited to, bonding, selective bonding, release layers, surface activation, surface passivation, surface protection, electrical conduction, electrical insulation, surface decoration, reflection of IR or visible or UV light, absorption of IR or visible or UV light, radiation of IR radiation, and food flavouring.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1904365.2 | Mar 2019 | GB | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/059016 | 3/30/2020 | WO | 00 |
