The invention concerns methods and an apparatus for decorating a surface of an item, in particular a section bar or a piece of sheet metal.
Methods are known that enable a multilayered decoration to be applied to a flat surface of an item, reproducing for example the veins of wood or marble.
According to such methods, after first preparing the surface of the item to receive the layers that make up the decoration, a bottom layer must be applied that will constitute the basic colour of the decoration. The item coated with the bottom layer is heated to the temperature of polymerisation of the material constituting said layer and maintained at that temperature for a set time. In such conditions, the material of the bottom layer undergoes a reticulation process and as it sets it stably grips the surface of the item.
On the set bottom layer, a decorative layer is then applied according to a desired decorative pattern, for example to reproduce the veins of a certain type of wood.
The decorative layer is not in itself sufficiently cohesive and is made to adhere to the bottom layer by means of the application of a final layer that covers both the layers underneath and by means of final heat treatment of the item coated with the three layers. This heat treatment occurs for a time and at a temperature that enable polymerisation of the final layer, which enables the decorative layer to be anchored to the bottom layer.
The final layer is transparent, in such a way as to keep the decoration below visible.
One defect of the prior-art methods is that in order to obtain a decorated item, at least three layers must be applied. This involves great consumption of material, prolonged processing time and the need to use particular equipment to apply each layer.
Furthermore, the item must be subjected to two heat treatments that enable the bottom layer and the final layer to polymerise completely. The decoration procedure requires enormous energy and rather great time consumption, which is responsible for high production costs.
Furthermore, the aesthetic result is not satisfactory because the final layer applied evenly to the entire surface of the item gives the decoration an unnatural flattened appearance. This is not desired when the decoration has to reproduce the appearance of a surface of wood or marble or of any other natural material.
Another disadvantage of the prior art is that it is apt to be applied only to the flat surfaces of an item. It is in fact rather difficult to apply the decorating material to the concave or convex zones of the item to be decorated, where it is almost impossible to obtain good resolution. Similar disadvantages occur if surfaces have to be decorated having grooves, protrusions or recesses, or edge zones of items such as section bars or sheet metal.
One object of the invention is to improve the methods and apparatuses for decorating items, in particular sheet metal and section bars.
A further object is to supply methods and apparatuses that enable non-flat surfaces to be decorated.
A yet further object is to provide a method for decorating an item that involves reduced consumption of material applied to the surface of the item to be decorated.
Another object is to provide a method for decorating an item that requires fast execution time and low energy consumption. In a first aspect of the invention, an apparatus is provided comprising transfer means suitable for coming into contact with a shaped surface of an item to transfer thereupon a fluid material and applicator means suitable for applying said fluid material onto said transfer means, characterised in that said transfer means is deformable so as to be able to adapt itself according to said shaped surface.
In a second aspect of the invention a method is provided comprising bringing transfer means into contact with a shaped surface of an item to transfer a fluid material from said transfer means to said shaped surface, characterised in that during said transferring said transfer means is deformed to adapt itself to said shaped surface.
Owing to these aspects of the invention, a fluid material can be applied to a shaped surface of an item, such a surface being shaped even according to a complicated geometry, for example having a curved profile or provided with recesses or reliefs. In fact, thanks to its deformability, when transfer means interacts with the shaped surface of the item, it can be deformed according to the geometry of the shaped surface and also apply the fluid material even to points situated at different heights from one another.
The apparatus and the method according to these aspects of the invention enable in particular the fluid material to be applied to edge zones of an item, such as, for example, zones arranged on the edges of a main substantially flat surface of this item.
According to a third aspect of the invention, a method is provided for decorating an item, comprising distributing on said item polymeric base layer means, applying onto said base layer means a decorative pattern defined by decorating means in liquid form, fixing said decorative pattern to said item, characterised in that said fixing comprises anchoring said decorating means to said base layer means, without applying further fixing layers to said item.
Owing to this aspect of the invention, it is possible to obtain a decorating method that enables the number of layers deposited to the surface of the decorated item to be limited.
In fact, no fixing means is provided that is additional to base layer means and to decorating means, and in particular recourse to the transparent layer provided for in the prior art is eliminated. In this way, it is possible to reduce consumption of the material to be applied to the item and to make decorating operations faster.
Furthermore, the decorative pattern takes on a more pleasant and natural appearance as it does not appear ‘flattened’ by additional fixing layers.
In a fourth aspect of the invention, the use of a paint that is settable by means of UV rays for decorating a section bar is provided.
Owing to the fourth aspect of the invention, section bars can be recovered that have been decorated to a poor level of quality in order to decorate them again. In fact, if the decoration is found to be of poor quality, the paint can be removed by means of a suitable solvent before being set by UV rays. The section bar, from which the paint has been removed, can then be decorated again to the desired quality. It is thereby no longer necessary to reject and then throw away the section bars decorated in an unsatisfactory manner.
In a fifth aspect of the invention, the use of a relief printing technique for decorating section bars is provided.
In a sixth aspect of the invention, the use of a gravure printing technique for decorating section bars is provided.
Owing to the fifth and sixth aspects of the invention, it is possible to obtain a particularly wide range of decorative effects associated with an excellent print definition.
The invention may be better understood and implemented by referring to the attached drawings that illustrate some non-limiting examples of embodiments, wherein:
In
However, it is also possible to apply the bottom layer 3 in the form of a liquid paint, for example, thermosetting.
The item 1 covered by the bottom layer 3 is then subjected to heat treatment at a temperature between 140° C. and approximately 180° C., for example 170° C., for about 10 minutes so as to obtain partial firing of the bottom layer 3. After this treatment, even if the bottom layer 3 has not undergone complete reticulation, the particles that make it up have acquired good cohesion between themselves. The bottom layer 3 can thus be an excellent support for the decorative layer 4, after acquiring good adhesive properties in relation to the decorative layer 4. Furthermore, to obtain partial firing of the bottom layer 3, lower energy consumption is necessary than would be necessary to obtain its complete firing.
Subsequently, the decorative layer 4 is applied by distributing on the bottom layer 3 a liquid decorative material 7 according to a desired decorative pattern. The liquid decorative material 7 may in particular be a thermosetting paint, applied by means of gravure printing or relief printing technique.
A phase of complete firing of item 1 covered by the partially polymerised bottom layer 3 and by the liquid decorating material 7 follows. In this phase, item 1 is maintained at a temperature between approximately 180° C. and approximately 220° C. for a time between 10 and 40 minutes.
The liquid decorating material 7 can also be a paint settable through exposure to UV rays. In this case, if the decorative layer 4 has faults, it is possible to remove the liquid decorating material 7 before exposure to UV rays by using a suitable solvent and then applying a new decorative layer 4 onto the same item 1. This enables the items to be recovered, and in particular the section bars, whereupon a low-quality decoration was erroneously applied, by decorating the items again until the desired quality of decoration is obtained.
The paint that is settable by UV rays can be used not only to decorate items according to the above method but can also be used in other known methods of decoration, particularly applied to section bars.
The liquid decorating material 7 can be applied by means of an apparatus 11 of the type shown in
The decorating roller 9 can operate according to a relief printing or gravure printing principle.
In the example in
The decorating roller 9 may be provided with an external layer in rubber, whilst the feeder roller 8 may be in steel, rubber, or another material.
In an embodiment that is not shown, the decorating roller 9 operates according to a rotogravure technique, in other words it receives the liquid decorating material 7 within a plurality of cavities with which the roller is externally equipped and transfers it to the surface 2, thereby forming a pattern defined by those cavities.
The rotation axis of the feeder roller 8 coincides with the geometrical axis of the roller itself and is substantially parallel to the rotation axis of the decorating roller 9, said axis also coinciding with the geometrical axis of the latter roller. The liquid decorating material 7 is transferred from the feeder roller 8 to the decorating roller 9 by contact between the two rollers rotating reciprocally: the rotating directions of each roller may be opposite, as shown in
The liquid decorating material 7 is applied by the decorating roller 9 to the item 1, which may, for example, be a section bar or sheet metal. The item 1 is conveyed by a conveyor belt 10 arranged below the decorating roller 9 along an travel direction F coinciding with the rotation direction of the decorating roller 9.
The apparatus 11′ can also be used if side surfaces of section bars have to be decorated, in other words, surfaces arranged on the edges of a main surface of the section bar itself.
These side surfaces may be provided with a curved geometry as indicated in
The apparatus 11′ comprises applicator means 12 provided with an applicator roller 19 whereupon the pattern is obtained that one wishes to transfer to the item 1′. A feeding system that is not shown feeds the applicator roller 19 with a cladding material 7′, which is then applied by means of the applicator roller 19 to transfer means 14 suitable for transferring the cladding material 7′ to the surface 2′. Transfer means 14 comprises a support belt 13 of elastomeric material, for example rubber or silicon, closed in a loop, provided with a substantially continuous surface, in other words almost free of openings. The belt 13 is wound around a cylindrical drum 15 and a shaped drum 16, both of which are made to rotate in the same direction around respective rotation axes, by means of motor means not shown. The shaped drum 16 is delimited by a profile 17 substantially corresponding to the further profile 17′ of the surface 2′ and the belt 13, thanks to the deformability of the material that makes it up, adapts itself to the profile 17 in the zone of contact with the shaped drum 16. In other words, the surface of the belt 13 wound to the shaped drum 16 mates locally with the further profile 17′ of the item 1, which enables the cladding material 7′ to be transferred to any surface, no matter how complicated.
It should be noted that the cylindrical drum 15 acts as contrast means providing a rigid limit for the applicator roller 19. The cylindrical geometry of the drum 15 simplifies the application to the belt 13 of the cladding material 7′, inasmuch as it makes it possible to use a cylindrically shaped applicator roller 19 rather than one shaped in another way.
The rotation axis Z1 of the cylindrical drum 15 and the rotation axis Z2 of the applicator roller 19 are parallel to one another. In the example in
For example, in
This embodiment can be used if a cladding material 7′ has to be applied in the liquid state having low values of viscosity.
In this case, providing a cylindrical drum 15 with a horizontal axis enables the risk to be reduced that the cladding material 7′ runs towards the bottom zones of the applicator roller 19 due to the force of gravity.
Naturally, different solutions can be adopted, and in particular different spatial arrangements of the drums 15 and 16, of the belt 13, and of the applicator roller 19, if particular reasons, for example of space, make this necessary. The belt 13 can transfer the cladding material 7′ to the item 1 in a uniform manner or according to a decorative pattern.
In the latter case, the belt 13 can be provided with a uniform surface, in particular smooth, whereupon the decorative pattern is formed by the applicator roller 19, for example by relief printing or gravure printing techniques.
In an embodiment that is not shown, it is also possible for the belt 13 to be externally provided with a plurality of cavities or protrusions defining the decorative pattern to be obtained on the item 1′. In this case it is sufficient to directly feed the cladding material 7′ to the belt 13 using a prior-art feeding system without having to resort to the applicator roller 19 upon whose surface the pattern to be transferred is etched.
During their path in the forward travel direction F, the section bars interact with transfer means comprising a silkscreen printing belt 32, a portion of which is shown in detail in
The silkscreen printing belt 32 may be created starting with a synthetic textile formed by thin wires, wherein the openings 35 are identified between the warp and the weft. In preset zones of the fabric it is possible to apply a resin that by closing the openings 35 creates the impermeable zones 34. If one wishes to apply onto the section bar a uniform layer of paint rather than a decorative pattern, a silkscreen printing belt 32 without impermeable zones 34 can be used that is thus permeable to the paint along its entire surface.
The silkscreen printing belt 32 travels the path shown schematically in
Applicator means 38 arranged downstream of driving pulley 36 in relation to direction F1 feeds on the silkscreen printing belt a fluid material such as a paint, as shown by the arrow F2. Applicator means 38 may comprise a pipe or nozzle arranged near a region of the silkscreen printing belt 32 located inside the loop path travelled by it.
A first doctor knife 39 and a second doctor knife 40 arranged downstream of applicator means 38 on opposite parts of the silkscreen printing belt 32 remove excess paint, thereby ensuring that the paint is deposited only inside the openings 35. In particular, the first doctor knife 39 is arranged inside the loop path travelled by the silkscreen printing belt 32, whereas the second doctor knife 40 is arranged outside said path.
Downstream of the first doctor knife 39 and of the second doctor knife 40 a third doctor knife 41 is arranged that interacts with the surface of the silkscreen printing belt 32 opposite the surface with which the second doctor knife 40 had interacted. In the case in point, the third doctor knife 41 is positioned inside the loop path travelled by the silkscreen printing belt 32, in other words on the part opposite the second doctor knife 40 positioned outside said path. The third doctor knife 41 enables any particles of paint that have been pushed to the internal surface of the silkscreen printing belt 32 by the second doctor knife 40 to be removed.
Downstream of the third doctor knife 41 a shaped doctor knife 42 is provided that is mounted on a cylindrical support 43. The shaped doctor knife 42 presses the silkscreen printing belt 32 into contact with a section bar 44 conveyed forwards in the travel direction F by forward travel means 30, not shown in
As shown in
The silkscreen printing belt 32, which is by now devoid of paint, then continues along its path, winding itself again around the drive pulley 36 and subsequently receiving new paint from feed means 38. The drive pulley 36 may be provided with a further doctor knife 49 suitable for keeping the external surface of the driving pulley 36 free from any paint residues.
The cylindrical support 43 of the shaped doctor knife 42 is movable in a direction F3 that is transversal to the forward travel direction F of the section bar 44, in such a manner as to be able to be brought up to or moved away from the silkscreen printing belt 32 by actuating means that is not shown. In particular, to reduce wear to the silkscreen printing belt 32, the shaped doctor knife 42 is pressed against the silkscreen printing belt 32 only when a section bar 44 is conveyed forwards by the forward travel means 30 to a position facing the shaped doctor knife 42.
For this purpose, sensor means 50 is provided, shown only schematically in
The excess paint delivered by applicator means 38 is collected in a drip-tray 70 arranged below the path of the silkscreen printing belt 32 and indicated in
The apparatus 611 shown in
Instead of the shaped doctor knife 42 it is possible to use a pulley whereupon the silkscreen printing belt 32 is wound, the pulley having a profile mating with the profile of the section bar 44. The pulley acts as doctor knife means, inasmuch as it removes the paint from the openings 35 and transfers it to the section bar 44.
The apparatus 1011 has a structure that is similar to that of the apparatus 11 shown in
Owing to its deformability, the transfer roller 54 is deformed as it comes into contact with the section bar 44 and is then able to decorate a surface portion 55 comprising not only a flat portion 56 of the section bar 44, but also two edge portions 57 adjacent to the flat portion 56.
If one wishes to decorate the entire surface of the section bar 44, after decorating the surface portion 55 as indicated in
Owing to the deformability of the transfer roller 54, it is also possible to decorate surfaces provided with steps, recesses or zones in relief.
In the example in
In an alternative embodiment, the engraved roller can transfer to the transfer roller 54 a uniform layer of paint, if one wishes to apply the paint in a uniform manner onto the section bar 44 without defining particular patterns.
The apparatus 1011 can also be used for decorating only a part of the surface of a section bar, as shown in
Number | Date | Country | Kind |
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MO2003A000022 | Feb 2003 | IT | national |
Filing Document | Filing Date | Country | Kind |
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PCT/IB04/00046 | 2/3/2004 | WO |