Patent Application
20230383872
The present invention relates to a flexible hose according to the preamble portion of claim 1 as well as to a method for production of such a hose in large quantities and to a device usable for that purpose. In particular, the invention relates to a flexible vacuum cleaner hose and the production thereof, such as used on a large scale in an industrial environment, in trades and in private households.
In the suction or conveying of very fine particles by a hose consisting of a plastics material, such as, for example, polyethylene (PE), polypropylene (PP) or an ethylene vinyl acetate co-polymer (EVAC), for example by a vacuum cleaner, strong electrostatic charges are generated by the friction of the particles against the walls of the hose. These can abruptly discharge, sometimes even with formation of sparks, in the event of, for example, contact of the electrically charged suction hose with an earthed component or user. The discharges can be of such strength that damage occurs at electronic apparatus and/or sharp pain is triggered at the user, in the worst case a risk to life arising if, for example, a heart pacemaker is brought to a stop.
Moreover, spark discharges can ignite explosive dust/air mixtures, gas/air mixtures and solvent-vapor/air mixtures. A risk of electrostatic ignition can in that case arise not only from the charged conveyed material, but also from charged components of a vacuum cleaner, particularly the suction hose.
Such sudden discharges can be prevented if all parts, which conduct the particles, of the vacuum cleaner are electrically connected with one another for potential equalization and with a protective conductor of the associated electrical connector.
Against this background, use is increasingly made of suction hoses consisting of a highly resistive, electrically conductive material, for example PE, in which fine carbon particles are embedded, for suction of fine dusts. However, this material is expensive by comparison with pure PE and, moreover, leaves behind undesired abrasion tracks if the suction hose is drawn by its outer circumferential surface over a substrate. These abrasion tracks can be prevented by an additional protective layer applied to the outer circumference of the hose, but this is connected with additional cost and makes the suction hoses more expensive.
In order to create a remedy it has been proposed in document DE 20 2009 016 596 U1 to use a coiled suction hose of an economic basic material at which is provided at least one electrical conductor, which extends substantially over the coil length of the suction hose, for dissipation of electrostatic charge, wherein the electrical conductor has a width at most equal to the channel width of the suction hose. This electrical conductor can be formed as, for example, a plastics material layer with an embedded carbon component, as an electrically conductive wire extending helically or as an electrically conductive strip. With respect to the position of the electrical conductor, it can be inferred from this prior art that the electrical conductor is either embedded in the material of the suction hose or arranged at the inner side of the base of the helix channel, at the outer side of the base of the helix channel or inwardly or outwardly at the webs bounding the helix channel.
Document DE 296 02 061 U1 discloses a further electrically dissipative hose with helically extending wave crests and wave valleys adjacent thereto at its outer side. An outwardly stripped electrical conductor consisting of an uninsulated wire suitable for dissipation of electrostatic charges is deposited in the wave valleys. The electrical conductor is covered by a strip which consists of thermoplastic material and the longitudinal edges of which are fastened to the flanks of the wave crests by welding or glueing.
Further, in order to enable, in particular, improved dissipation of electrical charges by comparison with the afore-described hoses, which comprise a “single electrically conductive device”, a conveying hose has been proposed in document WO 2005/047748 A1, in which a combination of “two electrically conductive devices” for conducting away electrical charges is provided. One electrically conductive device is a region, which concentrically surrounds the interior of the hose and is bounded by the inner surface, of the hose wall, which through embedding of electrically conductive particles in the basic material is furnished with an electrical conductivity significantly increased by comparison with the basic material. The other electrically conductive device is a local electrical conductor element which extends in axial direction and which is directly connected with the region of increased electrical conductivity and is to conduct away charges, which are collected by this region, to ground.
In the case of the pressure hoses according to this prior art the two electrically conductive devices are directly embedded in the hose wall during extrusion or co-extrusion of the respective pressure hose, so that a one-part ready-to-use pressure hose is created in one work step.
On the other hand, a widely used practice, which is particularly preferred with respect to a satisfactory capability of maintaining shape under an internally prevailing vacuum, for producing flexible suction hoses consists of initially extruding a profile of a plastics material, which is then wound helically or spirally, wherein adjacent coils or windings of the profiles are welded or glued together. In this connection, for example, document WO 2012/160524 A1 discloses a flexible plastics material hose produced by winding an extruded profile, wherein electrical conductors can also be embedded in the profile during extrusion of the profile.
Finally, a flexible hose having an outer wall produced from a plurality of windings of an extruded and helically wound profile is known from document DE 20 2017 107 890 U1, which defines the preamble portion of claim 1. Adjacent windings of the profile are connected together by a seam, wherein the outer wall has an electrically conductive track which contains a conductive section of the extruded and helically wound profile and/or the seam. In that case, the conductive section consists of an electrically conductive plastics material. The electrically conductive track additionally contains an electrically conductive thread, which at the outer wall of the hose is in electrical contact with the conductive section of the extruded and helically wound profile and/or the seam and, in particular, is embedded in the seam or in a groove provided in the profile. This electrically conductive thread is thus similarly a helically-wound integral component of the finished suction hose.
A disadvantage of the previously known electrically dissipative flexible hoses with “doubled dissipation” resides in the fact that for a good electrical dissipation capability of the hose a comparatively large amount of electrically conductive materials has to be provided in the hose, which materials due to integration thereof in the hose are also very difficult to recover, if at all.
Starting from the prior art according to document DE 20 2017 107 890 U1 the invention has the object of developing a flexible hose, particularly a vacuum cleaner hose, in such a way that the hose has a good dissipation capability for electrostatic charges, yet the problems discussed above in this connection with respect to the prior art are addressed. In particular, the electrically dissipative flexible hose with use of a comparatively small amount of electrically conductive materials shall have improved suitability for recycling. The object of the invention further comprises indication of a method for production of such an electrically dissipative flexible hose and a device for application of an electrically conductive thread to such a hose, which enables production or partial making-up—which is as simple, quick and economic as possible—of the hose with at least one electrically conductive thread in large quantities.
These objects are fulfilled by a flexible hose, particularly vacuum cleaner hose, with the features of claim 1, a method for producing a flexible hose by the method steps of claim 11 and a device for application of an electrically conductive thread to an outer side of a flexible hose with the features of claim 16. Advantageous embodiments of the invention are the subject matter of the dependent claims.
According to the invention, in a flexible hose, particularly vacuum cleaner hose, having a wall which by an inner side delimits a cavity for the conveying of media and has at least at an outer side a profiling which as seen in section along a longitudinal axis of the hose has a wave shape with elevations and depressions, wherein provided at the outer side of the wall is at least one electrically conductive track extending around the wall and disposed in electrical contact with at least one electrically conductive thread electrically connecting mutually remote ends of the hose, the electrically conductive thread extends substantially along the longitudinal axis of the hose and transversely to the electrically conductive track and is secured to the outer side of the wall.
In other words, the electrically conductive thread—by contrast with the prior art discussed above—is not laid in the circumferential direction of the hose, but extends in longitudinal direction of the hose according to the invention, in which case it crosses the encircling electrically conductive track while producing an electrical contact and thus quasi an electrical short-circuit. Electrostatic charges collected in the electrically conductive track as a “first electrically conductive device” are thus conducted away directly via the electrically conductive thread as a “second electrically conductive device” to the ends of the hose.
Since the electrical conductive thread at the wall of the hose according to the invention does not encircle the longitudinal axis thereof, but as seen in plan view extends along or substantially parallel to the longitudinal axis of the hose, less electrically conductive material for this second electrically conductive device is needed by comparison with the prior art outlined above. This is not only of advantage with respect to a comparatively low electrical resistance, but is also accompanied by advantages in cost and weight.
This possibility of influencing on the electrical resistance of the hose by the electrically conductive thread constructed or arranged in accordance with the invention can also have the effect, depending on the respectively desired or required capability of electrical dissipation, of differently distributing the individual resistances of track and thread, for instance to reduce the electrical dissipation capability of the electrically conductive track, for example by reduction in the carbon content in a plastics material—which is made electrically conductive by addition of carbon—for the electrically conductive track, which similarly offers cost advantages.
Moreover, since the electrically conductive thread has been mounted on the outer side of the wall it is simpler—again by comparison with the prior art discussed in the introduction, in which all electrically conductive devices are integrated in the hose, more precisely in the wall thereof—to remove the electrically conductive thread of a hose, which is to be discarded, from the rest of the hose for recycling purposes.
Not least, the construction of the hose according to the invention advantageously allows, in the manufacture thereof, a (at least) two-stage procedure in which initially a basic hose with the electrically conductive track is produced as a first electrically conductive device before—only in a second step—this basic hose is enhanced with respect to an improved capability of electrical dissipation by application of the electrically conductive thread as a second electrically conductive device. As a consequence of this modular construction of the hose it is thus possible to produce hoses as desired or required with different electrical dissipation capability from a form of kit, which ensures a high degree of flexibility in hose production and also offers cost advantages.
The term “electrically conductive thread” here represents the most general understanding of an electrical conductor, the length dimension of which is very much greater than its width dimension and thickness dimension. In that case, the “thread” can in principle also be at the same time an electrical conductor and fastening measure, such as is the case, for example, with a narrow adhesive tape made electrically conductive or an adhesive made electrically conductive and coated in a narrow longitudinal track, be it—depending on the kind of hardening taking place—for example a two-component or multi-component adhesive, an adhesive reacting under visible light or ultraviolet light or of thermoplastic nature (hot-melt adhesive).
If the electrically conductive thread and the fastening member for it are two components, it is basically possible to lay the electrically conductive thread on the profiling of the hose and then or thereafter to conceal or coat it by, for example, a hot adhesive, an ultraviolet adhesive or an ultraviolet lacquer or a track of an appropriately reacting or setting synthetic material foam or casting resin. On the other hand and particularly with respect to production economically and with process reliability it is, however, currently preferred if the electrically conductive thread is secured to the outer side of the wall by an adhesive strip. In an advantageous embodiment the adhesive strip can in that case cover the electrically conductive thread to both sides as seen in circumferential direction of the hose, which is conducive to a best possible in-contact retention of the electrically conductive thread at the electrically conductive track.
Moreover, provision can be made for the electrically conductive thread or the adhesive strip, which covers the electrically conductive thread, to be surrounded at the outer side of the wall—in a given case as a further enhancement—by a braiding of the hose. In that regard the braiding can advantageously serve as (an additional) securing and/or as (a further) protection of the electrically conductive thread at the outer side of the wall of the hose. In an appropriate embodiment of the device for braiding of the flexible hose it is also possible to apply and secure the at least one electrically conductive thread to the outer side of the wall during the braiding. A combination of fastening of the electrically conductive thread by an adhesive strip and braiding of the hose presents itself particularly when the application of the electrically conductive thread and the braiding take place at different locations and/or at different times.
In principle, it is possible to provide the electrically conductive track at any position on the outer side of the wall of the hose as long as it is ensured that the at least one electrically conductive thread can electrically contact and short-circuit the electrically conductive track. However, it is preferred, particularly with respect to an easiest and most reliable possible contacting of the electrically conductive track by the electrically conductive thread, if the electrically conductive track is formed on the outer side of the wall near to or at the elevations of the profiling.
In an advantageous embodiment of the flexible hose provision can additionally be made for the hose to be provided at one or both of the mutually remote ends with a hose mounting member of an electrically conductive material, optionally also as an adapter, which at the finished hose preferably rotatably retains a further connecting piece with, for example, a cone or bayonet to guarantee correct hose connection with associated terminal equipment (for example a vacuum cleaner) or tool. It is then possible by way of the hose mounting member and the connecting piece optionally mounted thereon to transfer to the terminal equipment and the grounding thereof electrostatic charges collected by the electrically conductive track of the hose and, in particular, transferred by way of the electrically conductive thread to the hose ends, and thus conduct away or remove those charges. The hose mounting members and/or the connecting pieces mounted thereon can if required additionally be provided with metallic contacts. In a corresponding embodiment of the hose mounting members and/or the connecting pieces mounted thereon it is also advantageously possible for electrostatic charges to be conducted away via the hose to terminal equipment such as, for example, a vacuum cleaner, which charges occur, for example, during an abrading or polishing process at/in an abrading machine. This can be of interest especially when the machine itself does not have an earthed mains connection or alternatively is driven by compressed air or with use of battery technology.
The following two variants, in particular, present themselves for attaching the afore-mentioned hose mounting members to the hose ends: In the first variant, when the profiling of the hose at the outer side is helical, the end of the hose can be screwed by the helical profiling into an associated internally threaded section of the hose mounting member, wherein the electrically conductive thread is clamped between the profiling and the internally threaded section with formation of an electrical contact.
Such an embodiment advantageously allows “refitting” of a defective hose such as can be desired, for example, by professional users, in that the hose mounting member is unscrewed from the defective hose, the defective or leaking hose section is cut off and the hose mounting member is then screwed back onto the appropriately shortened hose. A further advantage of this variant is that, in the event of repair of the hose, re-establishing contact of the electrically conductive thread with the hose mounting member takes place in particularly simple manner as a consequence of the mentioned clamping of the electrically conductive thread between the profiling of the hose and the internally threaded section.
If such a repair possibility of the hose is not required or, for example, in order to reduce production costs is not desired, in the other variant the end of the hose can be plugged into an associated receiving section of the hose mounting member and glued to the hose mounting member by an electrically conductive adhesive, into which the electrically conductive thread extends with formation of an electrical contact. It is obviously also possible to realize the two variants at the ends of one and the same hose if the hose is to be equipped with not just hose mounting members of one variant.
In principle, the basic hose can be formed by, for example, blow-molding of a suitable plastics material, optionally also with an electrically conductive track wound around the hose in a subsequent step. Thereagainst, however, it is preferred if the wall of the hose is formed overall from a helically wound profile, with adjacent windings of the profile being connected together in media-tight manner. Advantages of such a wound hose by comparison with a blow-molded hose consist particularly in that the hose can be formed with a substantially smooth inner surface and accordingly small flow losses as well as only mild noise output in operation and in addition higher levels of suction performance can be realized as a consequence of good shape stability and restoring capability of the hose.
In a preferred embodiment of the wound hose the adjacent windings of the profile are connected together by a hot-melt adhesive in media-tight manner. This ensures production of the basic hose in a manner which is reliable in terms of process, rapid and economic. However, other possibilities of connection, for example, production of a material couple between the individual profile windings by laser welding, are also conceivable.
With respect to the method, the present invention provides a method for producing a flexible hose, which comprises at least the following three method steps a) to c): a) forming a basic hose having a wall which by an inner side delimits a cavity about a longitudinal axis and has at least at an outer side a profiling which as seen in section has a wave shape with elevations and depressions, wherein the wall is formed from an electrically conductive material or at least one electrically conductive track is formed at the outer side of the wall so that the electrically conductive track extends around the wall; b) applying at least one electrically conductive thread to the outer side of the wall so that the electrically conductive thread extends substantially along the longitudinal axis and transversely to the electrically conductive track; and c) securing the electrically conductive thread to the outer side of the wall so that the electrically conductive thread electrically contacts the electrically conductive track.
Of significance here is the separation of the method steps a) of forming the basic hose on the one hand and b) of applying and c) securing the electrically conductive thread to the outer side of the wall on the other hand. In the result, this leads to the afore-described recycling advantages, because the electrically conductive thread subsequently applied/secured to the outer side of the wall can fundamentally be more easily removed again than a conductor which is an integral constituent of the basic hose.
This separation of the method steps a) on the one hand and b) and c) on the other hand, however, also offers the advantage that in the manner of a construction kit system a hose of the same basic type—which indeed has the electrically conductive track, but (still) has no increased electrical dissipation capability—can, depending on the respective electrical dissipation requirements, be further enhanced by application/securing the electrically conductive thread or even not so enhanced if this is not necessary or desired. Thus, it is also possible to further electrically equip a hose of the same basic type selectively in correspondence with the respective requirements or wishes by the application/securing of different electrically conductive threads which, for example, differ in kind, material, dimensions and/or number.
As already mentioned further above, in step a) of forming the basic hose use can, in principle, be made of a blow-molding process. On the other hand, particularly with respect to simplest possible integration of the electrically conductive track in the hose, it is, however, preferred if in the step a) of forming the basic hose initially a profile of an electrically conductive plastics material is extruded or a profile of two plastics materials of different electrical conductivity is co-extruded so that the profile comprises at least one electrically conductive track, whereupon the profile is helically wound for formation of the wall of the basic hose, in which case adjacent windings of the profile are connected together in media-tight manner. In that regard, for preference the adjacent windings of the profile are, in a manner which is particularly reliable in terms of process, media-tightly connected together by a hot-melt adhesive.
In addition, steps b) of applying and c) of securing the electrically conductive thread to the outer side of the wall can in principle be performed in succession, particularly when the electrically conductive thread and the fastening member for it are two distinct components of the hose. Thereagainst, especially with respect to the most rapid and efficient production possible, it is, however, preferred if the steps b) of applying and c) of securing the electrically conductive thread to the outer side of the wall are performed at the same time, even when the electrically conductive thread and the fastening member for it are two distinct components of the hose.
After execution of the steps a) to c) the hose is already present as a semi-finished plastics material product which in a given case can be supplied as a roll product for further making up, for example, at the manufacturer of terminal equipment such as a vacuum cleaner. The preferred further making-up of the hose can, however, also take place at the hose manufacturer, for example directly subsequent to the production of the semi-finished plastics material product in that after step c) of securing the electrically conductive thread to the outer side of the wall a hose mounting member of an electrically conductive material, which electrically contacts the electrically conductive thread, is attached to one or both of the mutually remote ends of the hose cut to length.
With respect to the device, according to the invention a device for applying an electrically conductive thread to an outer side of a flexible hose is proposed, which has thereat, i.e. at an outer side, a profiling which as seen in section along a longitudinal axis of the hose has a wave shape with elevations and depressions, with the feature that an applicator for the electrically conductive thread is provided and has a rotatable applicator wheel similar to a stock wheel or cell wheel, to the outer circumference of which applicator wheel the electrically conductive thread can be fed and which applicator wheel is adapted to enter into interlocking engagement with the profiling of the hose layable in a hose support so that when the applicator wheel is rotating a relative advance movement between the hose and applicator takes place, in which the applicator wheel applies the electrically conductive thread to the profiling of the hose along the longitudinal axis of the hose while following the elevations and depressions.
Through the embodiment of the applicator wheel in accordance with the invention, which is capable of meshing with the profiling at the outer side of the hose in the manner of a rack drive, there advantageously results a constrained coupling of advance movement and coating/application movement for the electrically conductive thread. As a result, on the one hand it can be ensured that an appropriate or associated length of electrically conductive thread is always deposited or applied per length of hose, which can be conducive particularly to uniform and/or stress-free application of the electrically conductive thread to the profiling of the hose.
On the other hand, it is possible to advantageously use only one drive in order to generate both movements, i.e. relative advance movement for the hose and coating or application movement for the electrically conductive thread. Thus, for example, it is possible for the applicator to be—actively—moved with respect to the hose or the hose to be—actively—moved with respect to the applicator (relative advance), whilst the applicator wheel as a consequence of the interlocking engagement with the hose—passively—rolls thereon and lays down the electrically conductive thread (coating or depositing). In addition, it is possible to fix the applicator and to—actively—rotationally drive the applicator wheel (coating or depositing of the electrically conductive thread), wherein the hose as a consequence of the interlocking engagement between the applicator wheel and the profiling of the hose is—passively—drawn away under the applicator wheel (relative advance). Moreover, there is the possibility of designing the applicator to be movable and to—actively—rotationally drive the applicator wheel (coating or depositing of the electrically conductive thread) so that the applicator together with the applicator wheel by virtue of the interlock between the applicator wheel and the profiling of the hose—passively—moves with respect to the optionally suitably fixed hose (relative advance).
If at least two drives respectively associated with the applicator, the applicator wheel or the hose are provided, then it is possible in addition to co-ordinate the generated movements with respect to movement execution (speed, acceleration) with, for example, use of a suitable electronic system, for example to deposit or attach the electrically conductive thread on or to the profiling of the hose with little tension or, especially, “loosely”, thus relieved of tension.
One of the criteria with regard to which components or subassemblies of the device are constructed or arranged to be stationary and which are constructed or arranged to be movable is the length of the flexible hose to be provided with the electrically conductive thread. In the case of a hose as a roll product or in endless production it is possible, for example, to construct the applicator to be stationary and thereagainst to move the hose with respect to the applicator. Particularly with respect to simple realization of the application process with hoses of defined length a construction of the device is currently preferred in which the hose rest is mounted in stationary position on a frame of the device, wherein the applicator comprises an applicator carriage which carries the applicator wheel and is guided at the frame to be displaceable along the hose rest.
Moreover, with respect to reliable process performance it is also preferred if the applicator wheel is drivably connected with a rotary drive so that the applicator wheel can be actively rotationally driven.
Moreover, an embodiment of the device is preferred in which the applicator comprises an applicator arm on which the applicator wheel is rotatably mounted and which is pivotable with respect to the hose rest about a selectively fixable pivot axis. It is thus possible to use the device with its applicator, without significant conversion work, for hoses of different thickness and/or basic shape (for example cylindrical or conical at the outer circumference). In the case of, for example, conical hoses the applicator wheel can thus follow without problems the thickness of the hose increasing and decreasing over the length of the hose. Through fixing the pivot axis for the applicator arm it is in addition possible to advantageously generate and set a specific pressing pressure of the applicator wheel against the hose in the case of, for example, a hose, which is cylindrical at the outer circumference, with use of the intrinsic elasticity of the hose.
Furthermore, the arrangement is preferably such that the applicator arm together with the applicator wheel and the pivot axis thereof is so positioned with respect to the hose rest that a torque about the pivot axis in the direction of the hose rest results and/or that the applicator arm is resiliently biased about its pivot axis in the direction of the hose rest. The intrinsic weight of the applicator arm together with the components mounted thereon or the center of gravity thereof with respect to the pivot axis and/or the spring force acting on the applicator arm can be so provided or selected in simple manner in the case of such an embodiment that the applicator wheel on application of the electrically conductive thread to the hose always bears against the hose by a defined pressing force.
As already mentioned in the introduction, it is in principle possible to initially position the electrically conductive thread at or in the profiling of the hose by the applicator wheel and secure it to the hose only in a succeeding step, so that the electrically conductive thread is in permanent electrical contact with the electrically conductive track of the hose. Particularly with respect to a largest possible throughput and a high level of process reliability in hose production it is, however, preferred if the application and the securing of the electrically conductive thread to the hose take place at the same time. For this purpose an embodiment of the device is currently preferred in which the applicator comprises a feed device for the electrically conductive thread and a feed device for an adhesive strip, wherein the electrically conductive thread and the adhesive strip can be fed from the feed devices to a pair of guide rollers which are adapted to combine thread and adhesive strip before onward guidance to the applicator wheel takes place. It can thus be ensured on the one hand in simple manner that the electrically conductive thread experiences precise positioning and good securing to the hose and on the other hand that the electrically conductive thread can thus be protected, during application, by the adhesive strip against, for example, excessive tension.
Finally, it is preferred if the applicator wheel has between two hub sections a plurality of axle pins which are uniformly distributed over the circumference and which each rotatably mount a hollow-cylindrical sleeve as pressing body for the electrically conductive thread. During application and securing of the electrically conductive thread to the hose this measure is also advantageously conducive to mechanical load relief of the electrically conductive thread.
Further features, characteristics and advantages of the electrically dissipative flexible hose according to the invention, the method according to the invention for production of such a hose and the device according to the invention for application of an electrically conductive thread to a profiled outer side of a flexible hose are evident to the expert from the following description of preferred embodiments.
The invention is explained in more detail in the following by way of preferred embodiments with reference to the accompanying, partly schematic, drawings, in which the same or corresponding parts or sections are provided with the same reference numerals, wherein in the drawings:
A vacuum cleaner hose, as an example of a flexible hose, is denoted generally by the reference numeral 10 in the figures. According to, in particular,
In that regard, according to, for example,
In the illustrated embodiments the hose is a wound flexible hose 10, i.e. a hose 10 of which the wall 12 is formed from a profile 26 helically wound around the longitudinal axis 22, wherein adjacent windings of the profile 36 are connected together to be sealed relative to media. The profile 36 shown here by way of example has as seen in cross-section two regions, namely a region on the right in each of
It is also evident from
In the illustrated embodiments the profile 36 is co-extruded from two plastics materials of different electrical conductivity so that the profile 36 includes the electrically conductive track 28. In that regard, a principal part of the profile 36 can consist of a non-conductive plastics material such as, for example, polyethylene (PE), polypropylene (PP) or an ethylene vinyl acetate copolymer (EVAC), whereas the electrically conductive track 28 is formed from a conductive plastics material. The latter can be, for example, a PE, PP or EVAC basic material which is rendered conductive by addition of conductive components such as, for example, carbon particles.
However, in the alternative it is also possible in correspondence with the respective electrical dissipation requirements to co-extrude the profile 36 entirely from such electrically conductive plastics materials and, in a given case, to even extrude with material uniformity. In such a case the profile overall forms the electrically conductive track by its outer surface.
As far as the hot-melt adhesive 38 is concerned this can similarly consist of a plastics material such as, for example, PE or EVAC, which is either non-conductive or is made conductive.
By the term “electrically conductive thread” 30 generally used here there is to be understood on the one hand a metalized thread, cord or yarn, for example an elastic yarn of a plastics material such as polyamide (PA), which is provided with, for example, a silver coating or a coating of copper, gold or platinum promising very good conductivity, or, however, a track or a (adhesive) strip of a plastics material or synthetic resin made electrically conductive in suitable manner, but also on the other hand pure metallic conductors such as wires or strands of copper or the like, wherein the actual realization of the electrically conductive thread 30 depends on which demands are placed on the hose 10 with respect to, in particular, the electrical and mechanical properties thereof. Thus, for example, in the case of a flexible hose 10 which is subject in use to greater degrees of alternating bending loads or tension loads it has to be ensured that the electrically conductive thread 30 does not break or tear or do so prematurely, which tends to exclude metallic conductors, which may be liable to work-harden, from such a case of use. With respect to electrical conductivity, a specification with respect thereto can be, for example, that the entire hose has to have only a predetermined resistive impedance able to be achieved, for example, by suitable selection of the electrically conductive thread 30.
As already mentioned further above, at least one electrically conductive thread 30 is provided, i.e. in correspondence with the respective requirements it is also possible to provide several electrically conductive threads in order to, for example, reduce the electrical resistance in an overall arrangement and/or provide a—optionally multiple—redundant overall arrangement. In that regard, the electrically conductive threads 30 can run adjacent to one another or at least partly cross or intersect under electrical contact with one another. In such a case the electrical connection of the mutually remote ends 32, 34 of the hose 10 and the electrical contacting of the electrically conducting track 28 is achieved by the overall arrangement of electrically conductive threads 30. In other words, it is in principle possible that none of the electrically conductive threads 30 of such an overall arrangement by itself bridges the entire path between the mutually remote ends 32, 34 of the hose 10, but the overall arrangement and/or only a part or one of the electrically conductive threads 30 of such an overall arrangement contacts the electrically conductive track 28.
As, moreover,
In the embodiment according to
The afore-described hose 10 can in principle be produced as a roll product at the hose manufacturer and, for example, be supplied to the manufacturer of relevant terminal equipment such as, for example, vacuum cleaners, where further making-up of the hose 10 is then carried out, which usually comprises cutting the hose 10 to length and providing the hose 10 at the ends with use-specific end members. However, it is also possible—and frequently the case—that the hose manufacturer further makes up the hose 10.
In the embodiment in
In the hose mounting member 44, which is on the left in
On the other hand, in the case of the hose mounting member 46, which is on the right in
A method of producing the flexible hose 10 sofar as described comprises in general the following three method steps a) to c): In a first step a), formation is carried out of a basic hose comprising the wall 12 which by its inner side 14 delimits the cavity 16 about the longitudinal axis 22 and has at least at its outer side 19 the profiling 20 which as seen in section has the wave shape with elevations 24 and depressions 26, wherein the wall 12 in its entirety is formed from an electrically conductive material or at least the electrically conductive track 28 at the outer side 18 of the wall 12, so that the electrically conductive track 28 extends around the wall 12. The basic hose produced to that extent is in principle already capable of use, i.e. no specific requirements with respect to the capability of dissipating electrostatic charges are imposed thereon, thus this basic hose can already be made up by cutting to length and providing it with suitable end pieces.
Only in a following step b) is the application now carried out, in the case of higher demands on the hose 10 with respect to capability of conducting away electrostatic charges, of the at least one electrically conductive thread 30 to the outer side 18 of the wall 12, so that the electrically conductive thread 30 extends substantially along the longitudinal axis 22 and transversely to the electrically conductive track 28. In other words, in this step the encircling electrically conductive track 28 is short-circuited or at least prepared for that purpose by the electrically conductive thread 30.
In order, finally, to maintain this electrical state in further processing and in later use of the hose 10 or bring about that state for that purpose, securing of the at least one electrically conductive thread 30 to the outer side 18 of the wall 12 is carried out in a further step c) so that the electrically conductive thread 30—permanently—electrically contacts the electrically conductive track 28. This securing can, as already mentioned above, be effected by attaching or applying the adhesive strip 40 and/or the braiding 42 to the outer side 18 of the wall 12 of the hose 10.
Preferred sub-steps of the step a) of forming the basic hose comprise, as already similarly discussed above, initially a sub-step in which the profile 36 is extruded from an electrically conductive plastics material or co-extruded from two plastics materials of different electrical conductivity so that the profile 36 has at least the electrically conductive track 28 even if not fully electrically conductive. In a further sub-step the profile 36 is thereupon helically wound for formation of the wall 12 of the basic hose, wherein adjacent windings of the profile 36 are media-tightly connected together by, for example, the hot-melt adhesive 38, as is known per se.
With respect to rapid and efficient mass production of hoses 10 it is particularly preferred if the steps b) of applying and c) of securing the electrically conductive thread 30 to the outer side 18 of the wall 12 are performed at the same time. A device which can be used for that purpose is described further below.
Finally, after the step c) of securing the electrically conductive thread 30 to the outer side 18 of the wall 12 the afore-described hose mounting member 44, 46 of an electrically conductive material can, for example, be attached to one or both of the mutually remote ends 32, 34 of the hose 10, which is cut to length as desired or necessary, and electrically contacts the electrically conductive thread 30.
Details of a device 54 for application of an electrically conductive thread 30 (or several electrically conductive threads 30) to the outer side 18 of, for example, the afore-described flexible hose 10, can be inferred from
A hose rest 64 consisting of an elongate angle profile member with a V-shaped cross-section is erected on the transverse profile members 60 of the frame 56—see, in particular,
A core component of the device 34 is an applicator 68 for the electrically conductive thread 30, which—as described in more detail in the following—has a rotatable applicator wheel 70 similar to a stock wheel or cell wheel (see
In the illustrated embodiment the arrangement is such that the hose support 64 is mounted in stationary position at the frame 56, whereas the applicator 68 comprises an applicator carriage 72 which carries the applicator wheel 70 in a manner still to be described and—as can be clearly seen in a comparison of
The applicator 68 further comprises an applicator arm 82, on which the applicator wheel 70 is rotatably mounted in a manner still to be described and which is pivotable with respect to the hose support 68 about a selectively definable pivot axis 84, which can be best seen in
According to
If need be, the applicator arm 82 can also be manually pushed in the direction of the hose 10 and then fixed in this pressing position by fixing the clamping lever 90. In a variant, which is not illustrated in the figures, the applicator arm 82 can in addition also be resiliently biased about its pivot axis 84 in the direction of the hose support 64, for example by a tension spring, which is arranged to be effective in terms of actuation between the applicator arm 82 and lower part of the applicator carriage 72.
It will be evident to the expert that by these measures the applicator wheel 70 can be reliably held in engagement with the profiling 20 of the hose 10 resting on the hose support 64. In that case, hoses 10 with different diameters and shapes (for example substantially cylindrical or conical) can be processed, i.e. provided with an electrically conductive thread 30.
As, moreover, can be best inferred from
According to
In addition, a roll holder 108, at the free end of which an adhesive strip roll 110 is rotatably mounted and, in particular, similarly in cantilever manner, of the feed device 96 is mounted on the side of the head part 92 and the mounting profile section 106 remote from the pivot axis 84. According to, in particular,
Moreover, a spool holder 112, which in the illustrated embodiment carries four spools 114 with electrically conductive threads 30, the spools being rotatably plugged onto parallel axle pins (not illustrated), of the feed device 94 is mounted at the top on the mounting profile section 106. A fastening angle member 116 for an end of a hose 118, the other end of which is secured by a bracket 120 laterally to the mounting profile section 106, is mounted on the end of the spool holder 112 remote from the adhesive strip roll 110. Finally, this bracket 120 also holds a tubelet 122 for the feed, more precisely guidance of the electrically conductive threads 30 to the guide roller arrangement 98.
In this respect it is apparent that the adhesive strip 40 can be unrolled from the adhesive strip roll 110 of the feed device 96 and fed to the guide roller arrangement 98. At the same time electrically conductive threads 30 can be unspooled from the spools 114, collected by way of the hose 118 and—guided through the tubelet 122—fed to the guide roller arrangement 98, where the electrically conductive threads 30 are combined with the adhesive strip 40.
Moreover, a mounting block 124 of the mounting and drive arrangement 104 for the applicator wheel 70 is mounted below the head part 92 of the applicator arm 82. In the illustrated embodiment the mounting block 124 is of two-part construction, with a part which is on the left in
Finally, further details with respect to the applicator wheel 70 can be inferred from
As, in particular,
It will be apparent that through driving the applicator wheel 70 by the rotary drive 132 not only the electrically contacting application and securing of the electrically conductive threads 30 to the hose 10 thus take place, but also the advance movement between the applicator 68 and the hose 10, which rests on the hose support 64, is generated, in which the applicator carriage 72 as shown in
A flexible hose, particularly vacuum cleaner hose, has a wall which by an inner side delimits a cavity for the conveying of media and has at least at an outer side a profiling which as seen in section along a longitudinal axis of the hose has elevations and depressions. At least one electrically conductive track, which extends around the wall and is in electrically contact with at least one electrically conductive thread which electrically connects mutually remote ends of the hose, is provided at the outer side of the wall. The electrically conductive thread, which extends substantially along the longitudinal axis of the hose and transversely to the electrically conductive track, is secured to the outer side of the wall, whereby the hose in the case of use of a comparatively small amount of electrically conductive materials has improved suitability for recycling. In addition, a method for producing such a hose and a device usable for that purpose are proposed.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2020 006 493.0 | Oct 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/079433 | 10/22/2021 | WO |
