Method and apparatus for cold-stamping onto three-dimensional objects

Abstract

A method and an apparatus for cold-stamping onto a three dimensional object. In a first step, an adhesive is applied to the object at a first workstation. In a second step, a transfer film is pressed onto the object by a pressing device at a second workstation. At the same time, the adhesive is cured at the second workstation. As a result, the decorative material of the transfer film adheres to the object at the positions on the object which are provided with adhesive. If, following this, the transfer film is removed from the three-dimensional object after being pressed on, the decorative material remains on the object at the desired positions. At the positions at which in the first step no adhesive has been applied to the object, the decorative material does not adhere to the object but rather remains on the carrier film of the transfer film.

Claims

1. An apparatus for cold-stamping onto a three-dimensional object, the apparatus comprising: a holder for rotatably holding the object around an axis of rotation; a first workstation comprising a printer for applying an UV-adhesive to the object, and a second workstation comprising: a pressing device for pressing a transfer film onto the object, wherein the pressing device is made of silicone and comprises a thickness in the range of between 1 mm to 20 mm in a region to be penetrated by UV-radiation; and wherein the silicone comprises a hardness in the range of between 30 Shore A to 70 Shore A; and a UV-radiation source for generating UV-radiation at a wavelength in the range of between 250 nm to 420 nm for curing the UV-adhesive, wherein the second workstation is arranged such that when a portion of the transfer film is pressed by the pressing device, the UV-adhesive at the portion of the transfer film is cured simultaneously and wherein the pressing device is transparent for UV-radiation at least in partial regions and is arranged at least partially between the UV-radiation source and the holder; and at least one further workstation for applying an additional coating to the object in at least one of a region of a decorative material, regions adjacent thereto, or on an entire surface thereof downstream of the second workstation.

2. The apparatus according to claim 1, wherein the pressing device further comprises a flexible pressing layer.

3. The apparatus according to claim 2, wherein the pressing device and/or the pressing layer is/are formed to be flat or three-dimensional.

4. The apparatus according to claim 2, wherein the pressing device and/or the pressing layer comprise(s) at least partially a structured and/or textured surface.

5. The apparatus according to claim 1 further comprising a transfer film guide which is arranged to guide the transfer film tangentially with respect to an outer periphery of the object, wherein the pressing device is arranged such that it presses the transfer film onto the object along a contact line between the object and the transfer film.

6. The apparatus according to claim 1, wherein the pressing device can be moved such that a surface speed of the pressing device can be adapted to a surface speed of the object, and wherein the transfer film is able to be moved such that a surface speed of the transfer film can be adapted to the surface speed of the object.

7. The apparatus according to claim 1, wherein the pressing device comprises a cylinder which is able to be rotated about the cylinder axis, or a planar plate.

8. The apparatus according to claim 1, wherein the at least one further workstation is arranged to apply an additional lacquer layer.

9. The apparatus according to claim 1, wherein the first workstation for applying the adhesive, the second workstation for pressing the transfer film and curing the adhesive, and all further optionally present workstations are arranged in-line.

10. An apparatus for cold-stamping onto a three-dimensional object, the apparatus comprising: a holder for rotatably holding the object around an axis of rotation; a first workstation comprising a printer for applying an UV-adhesive to the object; and a second workstation comprising: a pressing device for pressing a transfer film onto the object, wherein the pressing device is made of silicone and comprises a thickness in the range of between 1 mm to 20 mm in a region to be penetrated by UV-radiation; and wherein the silicone comprises a hardness in the range of between 30 Shore A to 70 Shore A; and a UV-radiation source for generating UV-radiation at a wavelength in the range of between 250 nm to 420 nm for curing the UV-adhesive, wherein the second workstation is arranged such that when a portion of the transfer film is pressed by the pressing device, the UV-adhesive at the portion of the transfer film is cured simultaneously and wherein the pressing device is transparent for UV-radiation at least in partial regions and is arranged at least partially between the UV-radiation source and the holder; and at least one of a screen printer, a flexographic printer, and a digital printer for applying a coating to the object, partially or on an entire surface thereof, upstream of the first workstation for applying the adhesive.

11. The apparatus according to claim 10, wherein the pressing device further comprises a flexible pressing layer and wherein the pressing device and/or the pressing layer is/are formed to be flat or three-dimensional.

12. The apparatus according to claim 10, wherein the pressing device further comprises a flexible pressing layer and wherein the pressing device and/or the pressing layer comprise(s) at least partially a structured and/or textured surface.

Description

(1) The invention will be explained in detail hereinafter with reference to the drawings, in which:

(2) FIG. 1a shows a schematic view of a first workstation of a preferred embodiment of an apparatus in accordance with the invention;

(3) FIG. 1b shows a schematic view of a first workstation of a further preferred embodiment of an apparatus in accordance with the invention (i) in a side view and (ii) in a perspective view;

(4) FIG. 2 shows a schematic view of a second workstation of a preferred embodiment of an apparatus in accordance with the invention;

(5) FIG. 3 shows a schematic view of the first workstation of FIG. 1 and of the second workstation of FIG. 2 in a perspective view;

(6) FIG. 4 shows a schematic view of a first exemplary holding device;

(7) FIG. 5 shows a schematic view of a second exemplary holding device; and

(8) FIG. 6 shows a schematic view of a second workstation of a further preferred embodiment of an apparatus in accordance with the invention.

(9) FIG. 1a shows a first workstation 1 which is designed as a flexographic printing station. Mounted on a printing block cylinder 11 is a printing plate 12, which determines the motif in which the adhesive is to be applied to the object 4. By means of an anilox roller 13 the adhesive is transferred from a reservoir (not illustrated) to the printing plate 12. The adhesive is applied to the anilox roller 13 e.g. by means of a fountain roller printing unit or a chamber scraper system.

(10) The object 4 is held from the inside by a holding device 3 which is designed as a holding mandrel 31. By rotating the mandrel 31 about the axis of rotation 32, the object 4 can also be rotated about this axis. The printing block cylinder 11 together with the printing plate 12 is also rotated at the same time as the holding mandrel 31, so that the adhesive applied to the printing plate 12 is transferred to the surface of the object 4.

(11) FIG. 1b shows a first workstation 1 which is designed as a screen printing station. A screen 15 having a fine-meshed fabric determines the motif in which the adhesive is to be applied to the object 4 by virtue of the fact that the mesh openings of the fabric are made impermeable for the adhesive, e.g. by means of a template, at the positions where no adhesive is to be applied. A scraper 14 is used to press the adhesive through the fabric of the screen 15 onto the object 4.

(12) The object 4 is held from the inside by a holding device 3 which is designed as a holding mandrel 31. By rotating the holding mandrel 31 about the axis of rotation 32, the object 4 can also be rotated about this axis. At the same time as holding mandrel 31 rotates, a relative linear movement is effected between the holding mandrel 31 and the screen 15 so that as a result the object 4 is rolled along the screen 15. The scraper 14 remains stationary relative to the holding mandrel 31. Therefore, the adhesive is applied to the object 4 in accordance with the motif defined by the template.

(13) FIGS. 2 and 3 show a preferred embodiment of a second workstation 2. The holding device 3 with the object 4 held thereon was moved on from the first workstation 1 to the second workstation 2 after the adhesive was applied to the object 4. The second workstation comprises a film unwinding arrangement 22, on which the supply of transfer film 21 is received. The transfer film 21 is guided to the object 4 by means of a plurality of guide rollers 23. The guide rollers 23 are used to adjust inter alia the web tension of the transfer film 21, in order to guide the transfer film 21 without any folds to the object 4. Two further guide rollers 23a ensure that the transfer film is guided tangentially past the object 4. The used transfer film 21 is finally guided by further guide rollers 23 to a film wind-up arrangement 24 and is wound up thereon.

(14) In the contact region 29 between the object 4 and transfer film 21, the transfer film 21 is pressed against the object 4 by a pressing device. The pressing device comprises a cylinder 25 which is coated with a silicone layer 26 to compensate for any unevenness. The cylinder 25 is designed as a hollow cylinder so that a UV-radiation source 27 can be disposed in the interior thereof. In order to ensure that the UV-radiation emitted by the UV-radiation source 27 in the direction of the object 4 can exit the cylinder 25, the cylinder 25 and also the coating 26 are formed from materials which are transparent for the UV-radiation required for curing purposes. The cylinder 25 can be made in particular from soda-lime glass, borosilicate glass, PMMA (polymethacrylate, referred to colloquially as plexiglass) or polycarbonate (PC). The coating 26 is mechanically attached on the cylinder 25 in particular by means of clamping strips. However, this can also be achieved by adhesion by means of adhesives which are highly transparent in particular for the UV-radiation used and are stable over a period of time when subjected to UV-radiation.

(15) During operation of the second workstation 2, the holding mandrel 31 is rotated with the object 4, which is located thereon, about the axis of rotation 32, while at the same time the transfer film 21 is guided past the object 4. Furthermore, at the same time the cylinder 25 is rotated about the cylinder axis 28 so that the transfer film 21 is pressed against the object 4. The rotational speeds of the cylinder 25 and of the holding mandrel 31 and the transport speed of the transfer film 21 are adapted to one another such that these three elements are moved without rubbing against one another.

(16) The UV-adhesive is cured by the UV-radiation at the same time as the transfer film 21 is pressed onto the object 4. By virtue of the rotation of the object 4 and the tangential progression of the transfer film 21 with respect to the object 4, the transfer film 21 is then removed from the object 4 immediately after curing. At the positions where adhesive has been applied to the object 4, the decorative material (e.g. the metal layer) of the transfer film 21 adheres to the object 4 once the adhesive has cured. At the positions where there was no adhesive, the decorative material remains on the transfer film 21.

(17) Further steps for treating the object 4 can be carried out at further workstations (not illustrated). For example, the object 4 can have different colours printed thereon, the surface of the object 4 can be treated in order to ensure e.g. a better reception of colour, or finally the object 4 can be provided with a protective layer. These steps can be performed at workstations upstream or also downstream of the workstations responsible for cold-stamping. The workstations can be arranged e.g. in a longitudinal transfer system or in a revolving transfer system.

(18) By virtue of the fact that the cold-stamping method in accordance with the invention can be performed at workstations of a longitudinal transfer system or a revolving transfer system, without the object having to be transferred to a different holding device, it is possible to integrate the cold-stamping method in a problem-free manner into the process of producing the object.

(19) FIGS. 4 and 5 show exemplified embodiments of holding devices which can be used in an apparatus in accordance with the invention or with a method in accordance with the invention. The holding device illustrated in FIG. 4 comprises a holding mandrel 31, onto which the object is slid. The diameter of the holding mandrel 31 is selected such that the object is held in a frictionally engaged manner on the holding mandrel 31. In order to improve the manner in which the object is held on the holding mandrel 31, air can be extracted by suction through openings 33 at the free end of the holding mandrel 31, whereby the object is drawn onto the holding mandrel 31 by reason of the vacuum in the interior. As a result, the object is seated firmly on the holding mandrel 31 and can be processed at the workstations, even on the entire surface if required.

(20) The holding device illustrated in FIG. 5 holds the object 4 (in this case a bottle, for example) by virtue of the fact that at one end the object 4 is clamped in a holder 35 and at the opposite end is mounted in a rotatable manner in a counter bearing 36. By rotating the holder 35 about an axis, the object 4 is also rotated about its axis of rotation and can be processed at workstations. Such a holding device can then be used e.g. if one side of the object 4 does not comprise an opening large enough for a holding mandrel.

(21) FIG. 6 shows a further preferred embodiment of a second workstation 2. The guide of the transfer film 21 corresponds substantially to the embodiment illustrated in FIGS. 2 and 3 and will not be described again at this juncture. The pressing device which presses the transfer film 21 against the object 4 in the contact region 29 between the object 4 and transfer film 21 comprises in the embodiment of FIG. 6 a planar pressing plate 34 which is coated with a silicone layer 26 e.g. for compensating for any unevenness and for reducing the friction between the pressing device and transfer film 21.

(22) The UV-radiation source 27 is arranged above the pressing plate 34, i.e. on the other side of the pressing plate 34 than the transfer film 21. The pressing plate 34 and the coating 26 are formed from materials which are transparent for the UV-radiation required for curing purposes, which means that the UV-radiation emitted by the UV-radiation source 27 in the direction of the object 4 can pass through the pressing plate 34 and the coating 26. The pressing plate 34 can be made in particular from soda-lime glass, borosilicate glass, PMMA (polymethacrylate, referred to colloquially as plexiglass) or polycarbonate (PC). The coating 26 is mechanically attached to the pressing plate 34 in particular by means of clamping strips or screws. However, this can also be achieved by adhesion by means of adhesives which are highly transparent in particular for the UV-radiation used and are stable over a period of time when subjected to UV-radiation. During operation of the second workstation 2, the holding mandrel 31 is rotated with the object 4, which is located thereon, about the axis of rotation 32, while at the same time the transfer film 21 is guided past the object 4.

(23) The UV-adhesive is cured by the UV-radiation at the same time as the transfer film 21 is pressed onto the object 4. By virtue of the rotation of the object 4 and the tangential progression of the transfer film 21 with respect to the object 4, the transfer film 21 is then removed from the object 4 immediately after curing. At the positions where adhesive has been applied to the object 4, the decorative material (e.g. the metal layer) of the transfer film 21 adheres to the object 4 once the adhesive has cured. At the positions where there was no adhesive, the decorative material remains on the transfer film 21.

(24) As in the case of the embodiment of FIGS. 2 and 3, further steps for treating the object 4 can be carried out at further workstations (not illustrated).

(25) Of course, the invention is not limited to the holding devices which are illustrated. For the invention, any holding device can be used which renders it possible to hold the three-dimensional object in such a manner that all of the positions on the object which are to be processed are accessible.

(26) The second workstations illustrated in the drawings do not necessarily have to be used together with the first workstation illustrated in the drawings. In particular, it is not necessary for the first workstation to be a screen printing or a flexographic printing station. The first workstation could also be a digital printing station (e.g. ink-jet).

LIST OF REFERENCE NUMERALS

(27) 1 first workstation

(28) 2 second workstation

(29) 3 holding device

(30) 4 object

(31) 11 printing block cylinder

(32) 12 printing plate

(33) 13 anilox roller

(34) 14 scraper

(35) 15 screen

(36) 21 transfer film

(37) 22 film unwinding arrangement

(38) 23 guide rollers

(39) 23a guide rollers

(40) 24 film winding-up arrangement

(41) 25 pressing cylinder

(42) 26 pressing layer

(43) 27 UV-radiation source

(44) 28 cylinder axis

(45) 29 contact point

(46) 31 holding mandrel

(47) 32 axis of rotation

(48) 33 openings

(49) 34 pressing plate

(50) 35 holder

(51) 36 counter bearing