EP0326819B1 - Device for the dry embossing of an article by means of a heat-embossing foil and an embossing die - Google Patents

Abstract

Device for the dry printing of an article (12) by means of a hot embossing foil (10) and an embossing die (1) where the hot embossing foil (10) is stuck on to the article (12) corresponding to the embossing die (1) and, after a cooling period, removed from the article with the exception of the printed image. The die body (2) is constructed with such a thin wall that it deforms elastically locally on its surface (Il) when placed against the article (12) to be printed. On the side facing away from the die face (3), the die body (2) features a positive facing force transfer relief (7), which corresponds to the die face (3) or is of a similar design. An elastic pressure cushion (8) is positioned on the side of the die body (2) facing away from the die face (3) to provide the local elastic deformation of the die body (2). <IMAGE>

Description

The invention relates to a device for dry printing of a workpiece using a hot stamping foil and a stamp and using heat, pressure and time, in which the workpiece and the stamp moves relatively towards one another, with the hot stamping foil being held in contact, with the clamping of the stamping Heat is transferred and moved away again, the hot stamping foil being stuck onto the workpiece in accordance with the stamp and being detached from the workpiece after a cooling time with the exception of the printed image, with a receiving station for the workpiece, a cyclically operating feed device for the hot stamping foil and a heating device for the made of elastically preformable material and having a stamp body. The invention can be used in particular in the printing of flexible hollow bodies made of plastic or with a plastic layer arranged on their surface using the hot stamping foil printing method. For example, blown plastic bottles, especially for the cosmetics industry - regardless of the cross-section - can be printed. It does not matter how the surface of the workpiece to be printed is designed in detail; this surface can in particular be flat, convex-round, convex-oval or also concave.

The hot stamping foil printing mentioned here is a dry printing process in which the hot stamping foil is glued or melted onto the surface of the workpiece to be printed. The hot stamping foil itself consists of a carrier tape, a separating layer, expediently a protective lacquer, the actual color layer, which often contains an additional metal layer, and the adhesive or

Connection layer to the plastic surface to be printed. All other layers apart from the carrier tape are applied to the surface to be printed during the printing process and, after appropriate cooling, are torn off from the hot stamping film or the carrier tape where they were glued or connected to the surface to be printed. A device of the type described at the outset is known from DE-PS 34 21 029, in which the two essential previous printing processes, namely the lifting process on the one hand and the rolling process on the other hand, are described. DE-PS 34 21 029 in turn now shows a method for dry printing, in which the embossing stamp is brought into contact with the workpiece by continuous application over the entire stamp surface and the embossing stamp, at least in the region of the stamp surface, corresponds to the shape of the workpiece Is brought into shape. The embossing stamp consists of a base body, for. B. a thin metal strip, and a stamp body such. B. from a rubber mixture which has a stamp surface corresponding to the desired print image. The heat is generated in the base body and passes through the stamp body through heat conduction into the stamp surface, where it is transferred to the hot stamping foil and the surface of the workpiece to be printed.

In the hot stamping foil printing process, in addition to rigid stamping dies, more or less elastic stamping dies are used, so that the elevated points of the stamping die are to adapt to any unevenness on the surface of the workpiece to be printed. The elastic stamps are deformed at the elevated points with force. This applied force adapts the stamp surface of the stamp body to the unevenness on the surface of the workpiece to be printed; however, there are clearly noticeable distortions in the print. This is especially the case when using comparatively large ones Forces. In particular, fine lines or thin fonts are crushed and there is a distortion of the print that goes to illegibility. These disadvantages severely restrict the possible uses of hot stamping foil printing as soon as certain quality requirements are placed on the printed image.

As is known, the workpieces to be printed can only be produced with tolerances, that is to say in certain tolerance bands, with regard to the formation of their surface to be printed. The occurrence of unevenness, sink marks in two dimensions, etc. cannot be avoided. For example, in the case of a flat printed image which extends over such sink marks, there are places where the hot stamping foil does not have the necessary contact with the surface to be printed. This can be counteracted by pressing harder from the back of the workpiece, for example by inflating a bottle to be printed. Another possibility is to make the stamp thicker. Both measures can also be used in combination; however, they prove to be disadvantageous both individually and in combination. A stronger pressure from the back causes excessive strain on the sensitive rubber from which the stamp body is made, so that embrittlement and crushing damage take place. In addition, the fonts are easily crushed in this way. If, on the other hand, the rubber layer of the stamp body of the embossing stamp is made thicker, the paths of heat conduction become longer and larger. A larger temperature difference must therefore be provided for the transfer of the required heat, ie the base body in which the heat is generated must be heated to a higher temperature. This in turn also affects the temperature of the material of the stamp body to a greater extent and it finds one additional damage instead. Ultimately, this also results in a reduction in the service life of the die.

Certain improvements can be achieved if the positional deviations of the embossing stamp from the surface of the workpiece to be printed are automatically compensated for during the printing process, as described in international application WO 81/01536. The positional deviation of the die can be subdivided again by dividing the die into individual segments that are separately elastically supported, as shown in US-A-3,961,575. In many cases, such a subdivision is not possible, e.g. B. if continuous fine lines must be printed over the entire print image. Through the measures shown you can achieve a reduction in errors and deviations, but the bumps, z. B. in the wall thickness differences of a hollow body, must still be compensated for in the corresponding sub-areas. The negative influences on the quality of the printed image are basically retained with such measures.

The invention has for its object to provide a device of the type described above, with the workpieces with geometric deviations in the surface, for example with sink marks, bumps and / or wall thickness differences, especially with flexible hollow bodies, with good service life clean and with great performance can be printed using the hot stamping foil printing process, whereby the sensitive embossing stamp is subjected to as little thermal and mechanical stress as possible.

According to the invention this is achieved in that the stamp body is so thin-walled that when it is placed on the workpiece to be printed it rests in a locally elastically deforming manner on the surface thereof that the Stamp body on its side facing away from the stamp surface has a positive force transmission relief which corresponds to or is similar to the stamp surface, and that the stamp body on the side facing away from the stamp surface is assigned an elastic pressure pad for the elastic deformation of the stamp body. The stamp body is particularly thin-walled, in such a way that it can elastically deform locally within its surface, so that there is the possibility of following the unevenness and incidence on the workpiece to be printed within a flat surface, for example. A positive force transmission relief is provided on the back of the stamp body, that is to say points which deliberately serve to transmit forces to the stamp body and the stamp surface. These are not particularly large forces, but first and foremost to apply forces that are as small as possible locally, but which are sufficient to produce a clean print image. The relatively small forces also have an advantageous effect with regard to the service life of the embossing stamp and thus also of the stamp body, because the elastic material is not mechanically stressed to this extent. The resetting behavior of the elastic material of the stamp body as well as other components of the stamp is not damaged. This power transmission relief is positive, ie represents a positive. It has the same or similar appearance to the right side as the printed image on the workpiece which is to be produced. The contact surface of the power transmission relief can protrude from the rear surface of the stamp body or can also be enclosed flush in this surface. It is also possible to choose the width dimensions of the contact surface differently from the design of the stamp surface on the stamp body. However, both must always correspond to each other, ie there must be power transmission from the back to the front from the transfer relief to the stamp area. On the stamp body on the side facing away from the stamp side, an elastic pressure pad for the elastic deformation of the stamp body is arranged or in any case provided for action, so that with the help of this pressure pad the thin stamp body can be elastically deformed locally, so that sink marks and unevenness are bridged, specifically without the stamp body being loaded mechanically and thermally more than necessary. The ways in which the forces are conducted, that is to say ultimately the pressure applied to the elastic material of the stamp body, are very short. The same applies to the thermal load. Due to the local heating of parts of the stamp body in the event that the heating device is provided, for example, in the stamp body, there are short paths for heat conduction and the material of the stamp body is not thermally overstressed. If, for example, a temperature of 250 to 270 ° C. has to be provided in the stamp surface, the heating device is operated at about 260 to 280 ° C. where the heat is generated. The large, thin-walled body of the stamp has an advantageous effect on great flexibility and thus in compensating for the imperfections, sink marks and differences in wall thickness, when working with the smallest pressures in the pressure pad. This results in low mechanical stress on the stamp body and the stamp surface, and the stamping tool has a long service life. Furthermore, the rejects are considerably reduced, if not practically completely avoided, through the use of the device constructed according to the invention, because even workpieces that are tolerance-wise at the limit of the tolerance band are still reliably printed. It is also possible to generate different local temperatures at the various locations on the stamp surface and thus on the printed image by means of individual local training of the heating device. That way flat areas can be individually treated compared to fine lines. Due to the small wall thickness of the stamp body of the embossing stamp, spherical workpieces can also be printed to a limited extent. Furthermore, it is advantageous that the set-up time of a printing press, which is equipped with the new device, is considerably shortened because the embossing die adapts better and to a greater extent to the tolerances. Finally, the amount of energy used is significantly reduced. The thermal energy to be used in hot stamping foil printing is approximately 1/20 to 1/30 of the thermal energy previously required. The raised points on the stamp surface of the stamping die are pressed against the workpiece to be printed with less force than previously in the region of the unevenness of the workpiece, this pressing being done with very low pressure by the pressure pad. This avoids pinching with the material of the stamp body, so that there are no line thickness differences due to pinching. Finally, the pressure pad only has to be pretensioned to such an extent that the necessary force is generated in order to bring the raised points in the area of the stamp surface into contact with the unevenness on the surface of the workpiece to be printed, matched to the elasticity of the stamp.

The heating device can be provided on or in the stamp body and can be arranged locally in accordance with the printed image, and that the heating device also forms the power transmission relief. The heating device is designed as a printed circuit board, the individual conductors being guided and arranged such that they are at least similar to the printed image. Since the material of the heating device is inelastic because it consists of metal, hard points thus arise in the elastic material of the stamp body, namely the power transmission relief, which is effectively present without the after Back protruding raised areas are present. Since the heating device is no longer provided on the base body of the die, but directly on or in the die body, extremely small paths are created in connection with the small wall thickness of the die body, via which the heat must be transported by heat conduction. The heating device no longer extends flatly over the base body of the embossing stamp, but is arranged locally in accordance with the printed image, so that, as it were, each raised point of the stamp surface, which forms the printed image as a whole, is heated individually.

Another possible implementation is that the stamp body made of elastically deformable material is provided on one side of a carrier body and the force transmission relief made of elastically deformable material is provided on the other side of the carrier body. The carrier body itself can be a metal strip, in particular for handling purposes, or else a rubber band. In this embodiment, the locations of the power transmission relief project beyond the surface on the back of the stamp body, so that in this way they enable the transmission of minimal but sufficiently large forces by contact with the pressure pad.

The force transmission relief can be designed, in particular, on its contact surface to the pressure pad similarly, namely, the same, smaller or larger than the stamp surface of the stamp body. If the power transmission relief consists of a conductor track made of metal, it is expedient that the guide of the conductor track is ultimately smaller than the outline of the stamp surface of the stamp body. If, on the other hand, the power transmission relief consists of raised points made of elastically deformable material, an enlargement compared to the stamp surface of the stamp body can be useful here, ie the positive on the back The resulting letters and lines are larger in width and height than the letters that form the printed image in the stamp area. In this way, a reduction in the surface pressure between the power transmission relief and the surface of the pressure pad is achieved, which also has a positive effect on extending the service life. Exactly the same dimensioning of the power transmission relief is simple insofar as this relief can be easily molded as a positive from a negative. The same size training therefore has manufacturing advantages.

The heating device can be provided in the stamp body between the relief having the stamp surface and the power transmission relief and at the same time form the carrier body, so that the stamp body can be handled simultaneously with the aid of the carrier body or the heating device, i. H. can be held and guided in a machine. The carrier body has a double function.

The stamp body can be provided with the power transmission relief in the form of a reciprocating plate or a rotating belt. A reciprocating drive on a belt is also possible. The training in detail depends on the desired service life, the speed at which printing is to be carried out, etc. The device according to the invention makes it possible to create hot stamping stations which can also be used as work stations in combination with screen printing stations, because with the device according to the invention the working speed can be increased during hot stamping so that it reaches the working speed of the screen printing stations, so that both different printing stations can ultimately be operated in a work line side by side or in succession without interference.

However, it is also possible for the heating device to be provided outside the stamp body and for the heat to be transferred directly to the stamp surface. The heat transfer can be generated, for example, by an infrared source. The heat is applied directly to the stamp surface without contact or with contact via an intermediate roller or the like, so that in the event of the subsequent contact during hot stamping foil printing, it no longer has to travel any distance in the stamp body, but is directly available at the printing point.

A screen can be provided between the heating device and the stamp surface of the stamp body, the heating device and / or the screen being arranged to be stationary or adjustable. Such an aperture allows, for example in connection with an infrared heating source, to transfer heat specifically to the stamp surface and to leave the neighboring surfaces of the stamp body, which can act as a support surface, comparatively colder, so that printing errors are already impossible in this way . The screen can also be cooled, particularly when it is fixed in place, so that it does not itself become a radiant source due to the infrared radiation. However, it is also possible to place the diaphragm or a plurality of diaphragms on a circulating belt, this belt being able to be passed through a cooling chamber or the like in the rear run to dissipate the excess heat.

The hardness of the pressure pad should be adapted to the hardness of the material of the stamp body, in such a way that the elastic deformation of the stamp body is possible. If the stamp body is made particularly soft, the pressure pad is also made particularly soft. If the stamp body has a greater hardness, that must also Pressure pads will be able to overcome this greater hardness. Of course, it makes sense to choose the design that is as soft as possible, because it is not a question of generating a high contact pressure of the stamp surface against the hot stamping foil and thus of the surface of the workpiece to be printed, but only of the elastic, local deformation of the stamp body. This deformation should be such that, despite this deformation of the stamp body, all locations on the stamp surface are pressed against the hot stamping foil with approximately the same contact pressure.

The force transmission relief can be formed on its contact surface equal to the stamp surface of the stamp body and a distribution rubber band can be provided between the contact surface and the pressure pad. This rubber band protects the pressure-sensitive pressure pad against the force transmission relief being pressed into the material of the pressure pad and thus prevents damage to the pressure pad. The distribution rubber band supports the forces transmitted via it on the pressure pad over a larger area, which is useful for increasing the service life.

A hydraulic or pneumatic cushion, a cushion made of foam or the like can be provided as the pressure cushion. A pneumatically inflatable bellows also fulfills its function here. An embodiment of the pressure pad as a tampon is also possible.

A printed circuit board with a carrier film and a resistance metal track located thereon can be provided as the heating device, in accordance with the design and arrangement of the printed image. Of course, several resistance metal tracks can be arranged aucti. The carrier film only has the task of receiving and holding the resistance metal track. Both the carrier film as well the resistance metal track are extremely thin and can be arranged directly behind the stamp body, such that the resistance metal track is facing the stamp body. It is of course also possible to mold the circuit board into the material of the stamp body. In this case, there are particularly short paths of heat conduction.

A heat insulation layer made of elastic material can be provided between the carrier foil of the printed circuit board and the pressure pad. This layer can be part of the pressure pad or an independent layer made of a material that differs from that of the pressure pad.

The stamp body itself can be designed in some areas as a support mask, while in other areas it has the stamp surface. These two areas mentioned can also be made of different materials, for example. The stamp body having the stamp surface expediently consists of a material mixture which is a good heat conductor. In the area of the support mask, a material can be used which is poorly heat-conducting. In connection with the locally acting heating device, it is achieved that the required high temperature for embossing is only established where the stamp body has the stamp surface, while the temperature on the parts forming the support mask is lower, so that there is a detachment of the ink layer not done by the stamping foil. However, it is also possible to design the areas forming the support mask from a material which is a good conductor of heat, in which case these areas must then be cooled.

The pressure pad can be permanently connected to the stamp body, so that the stamping die is, as it were, in one piece. Split training is also possible although this is generally not recommended. The connection between the pressure pad and the stamp body enables the spring properties of the pressure pad to be matched precisely to the elasticity of the stamp body. The pressure pad can in particular have a greater wall thickness than the stamp body, so that local compressions of the pressure pad do not manifest themselves or only in a change in the contact pressure.

The pressure pad can also consist of heat-insulating material and thus take over the function of the heat insulation layer. A separate layer of thermal insulation is thus eliminated.

The pressure pad can be designed to generate a pressure of approximately 100 g / cm². This extremely low contact pressure makes it clear that it is not important to use high contact pressures for hot stamping foil printing; it is only necessary to achieve a good surface contact of the stamp surface even on the unevenness of the surface of the workpiece to be printed. The pressure pad primarily serves for the elastic deformation of the stamp body and the force to be applied by it is matched to this. In addition, it also ensures contact with the hot stamping foil or the contact of the hot stamping foil with the workpiece surface.

Figur 1

den Prägestempel in einer ersten Ausführungsform im Schnitt,

Figur 2

einen Schnitt durch einen Teil eines Prägestempels während des Heißprägefoliendrucks,

Figur 3

eine Ansicht der Teile des Stempelkörpers des Prägestempels, die die Funktion einer Stützmaske erfüllen, an einem Ausführungsbeispiel,

Figur 4

eine ähnliche Darstellung wie Figur 3 mit dem kompletten Stempelkörper,

Figur 5

eine Ansicht der zu dem Ausführungsbeispiel der Figuren 3 und 4 gehörenden Leiterplatte,

Figur 6

eine schematische Darstellung der für die Erfindung wesentlichen Teile der Vorrichtung beim Bedrucken eines ebenen Werkstücks,

Figur 7

eine weitere Übertragungsart beim Bedrucken eines zylindrischen Werkstücks,

Figur 8

eine weitere Ausgestaltungsmöglichkeit beim Bedrucken der konkaven Oberfläche eines Werkstücks,

Figur 9

eine weitere, grundsätzliche Anordnung beim Bedrucken eines zylindrischen Werkstücks,

Figur 10

eine weitere Möglichkeit beim Bedrucken eines ebenen Werkstücks,

Figur 11

eine weitere Anordnungsmöglichkeit beim Bedrucken eines ebenen Werkstücks,

Figur 12

eine weiter Ausführungsform des Prägestempels im Schnitt,

Figur 13

Detaildarstellungen verschiedener Ausführungsformen an einem Stempelkorper,

Figur 14

eine weitere Realisierungsmöglichkeit für die Ausbildung eines Prägestempels an einer Druckstation und

Figur 15

eine weitere Ausführungsform einer Druckstation.

The invention is further illustrated and described using several exemplary embodiments. Show it:

Figure 1

the embossing stamp in a first embodiment in section,

Figure 2

a section through part of a stamp during hot stamping foil printing,

Figure 3

1 shows a view of the parts of the stamp body of the embossing stamp which fulfill the function of a support mask, using an exemplary embodiment,

Figure 4

a representation similar to Figure 3 with the complete stamp body,

Figure 5

3 shows a view of the circuit board belonging to the exemplary embodiment in FIGS. 3 and 4,

Figure 6

1 shows a schematic illustration of the parts of the device that are essential to the invention when printing on a flat workpiece,

Figure 7

another type of transfer when printing on a cylindrical workpiece,

Figure 8

another design option when printing on the concave surface of a workpiece,

Figure 9

another basic arrangement for printing on a cylindrical workpiece,

Figure 10

another possibility when printing a flat workpiece,

Figure 11

another arrangement option when printing on a flat workpiece,

Figure 12

another embodiment of the embossing stamp in section,

Figure 13

Detailed representations of different embodiments on a stamp body,

Figure 14

another implementation possibility for the Formation of an embossing stamp at a printing station and

Figure 15

another embodiment of a printing station.

In Figure 1, the basic structure of an embossing stamp 1 is shown. The embossing stamp 1 has a stamp body 2, which consists of a rubber mixture and which bears a stamp surface 3 formed by raised spots, which in negative form corresponds to the printed image, that is to say the image appearing on the workpiece to be printed. Other areas of the stamp body 2 or the stamp surface 3 can form a support mask 4. In the material of the stamp body 2 or, as shown here, directly on the stamp body 2 on the side facing away from the stamp surface 3, a heating device 5 is arranged, which is essentially designed as a printed circuit board and can thus have a carrier film 6 on which one or more Resistance metal tracks 7 are arranged, in relation to the raised positions of the stamp surface 3, which must be heated accordingly. The comparatively hard and thus inelastic points of the resistance metal tracks 7 form a positive, recessed force transmission relief which serves to transmit small but necessary forces from the pressure pad into the stamp surface and thus onto the workpiece. On the back of the stamp body 2 thus formed, a pressure pad 8 made of compensating, resilient material, for example made of foamed plastic, is provided. The spring hardness of the pressure pad 8 is matched to the spring hardness of the material of the stamp body 2. A heat insulation layer 9 can be arranged between the pressure pad 8 and the stamp body 2 with the heating device 5. This heat insulation layer 9 may also be absent if the material of the pressure pad 8 itself provides sufficient heat insulation. It can be seen from Figure 1 that the stamp body 2 locally heated individually is there, where the stamp surface 3 is located. The areas of the support mask 4, however, are not heated. These areas of the support mask 4 will therefore assume a lower temperature on the surface than the stamp surface 3.

FIG. 2 shows a section of an embossing stamp 1, which has the structure shown in FIG. 1, at the moment of contact via a hot stamping foil 10 on the surface 11 of a workpiece 12 to be printed. The conditions are exaggerated to solve the problem of sink marks and to clarify irregularities in the course of the surface 11 of the workpiece 12. This surface 11 may have bumps 13, sink marks or the like as they occur in a surface which is in itself flat. A good print image on the surface 11 of the workpiece 12 is generated when, despite the unevenness 13, the raised areas of the stamp body, ie the stamp surface 3, come into contact with the corresponding areas on the surface 11. The widths 14 of the raised areas of the stamp surface 3, for example the font thickness, must not undergo any changes when compensating for the unevenness 13, that is to say in particular they must not be squeezed locally or, on the other hand, have insufficient contact with the hot stamping foil 10 and the surface 11. Too little contact would lead to defects in the printed image. Excessive contact leads to disturbingly deep impressions in the surface 11. It can also be seen from FIG. 2 that the pressure pad 8 per se only has to exert a comparatively low pressure force, in such a way that the stamp body 2, which itself is very thin , is deformed elastically to the required extent. The die 1 can be attached to a lifting head 15, which is only indicated schematically here, in accordance with a double arrow 16, while the workpiece 12 is supported on a table 17. The workpiece 12 can be a massive one Body, as shown, or also be formed as a hollow body.

FIG. 3 shows the view of the freely visible surface of the stamp body 2 of the embossing stamp 1. However, only the parts of the stamp body 2 that form the support mask 4 are shown. FIG. 4 then shows the complete view of the stamp body 2 of the embossing stamp 1, that is to say also those parts of the stamp body which form the stamp surface 3. The stamp area 3 appears here as a negative. It is understood that the surface of the stamp surface 3 and the support mask 4 lie in a common plane. The entire stamp body can also be made from a continuous piece of material. Due to the local assignment of the heating device, one part of the surface of the stamp body 2 is stamp surface 3 and the other part is a support mask 4. FIG. 5 shows the heating device 5 belonging to the exemplary embodiment of FIGS. 3 and 4, specifically a printed circuit board with a carrier film 6 and a Resistor metal path 7, which ends in connections 18, which are considerably wider than the remaining parts of the resistance metal path 7, so that the heat generated when current flows through this thin and low-profile resistance metal path at the points behind the raised areas of the stamp surface 3. This results in extremely short paths for heat conduction (cf. FIG. 1), so that a small temperature difference of approximately 10 ° C. between the temperature of the conductor track 7 and the stamp surface 3 is sufficient for the transport of the heat.

FIG. 6 once again illustrates the basic arrangement of the parts of the device shortly before reaching the contact, in which the hot stamping foil 10 is pressed by the stamping die 1 against the surface 11 of the workpiece 12. Figure 7 illustrates another arrangement possibility. The stamp 1 is here on the circumference of a roller 19 arranged. On the roller 19, which can be made of hard material, for example steel or plastic, the pressure pad 8, which consists of elastically flexible material, is initially arranged on the surface thereof. This pressure pad 8 can be permanently attached to the roller 19 here. Parts of the die 1, namely the die body 2 and the heat insulation layer 9, are interchangeably held on the circumference with the aid of a spring element 20. If a heat insulation layer 9 is not provided, the spring element 20 can also act directly on the carrier film 6 of the heating device 5. The workpiece 12 to be printed here has a cylindrical shape and can be, for example, a plastic tab. The hot stamping foil 10 runs between the workpiece 12 and the roller 19 with the stamp 1. It goes without saying that workpieces 12 with a flat surface 11 can of course also be printed with this device according to FIG. 7, as shown in FIG.

The embodiment according to FIG. 8 is particularly suitable for printing on a concave surface 11 of a workpiece 12. The stamp body 1, including the pressure pad 8, is here mounted on a shaped steel sheet 21, which itself is flexible to a limited extent. It can be seen that when the parts approach each other, the stamp surface 3 first comes to rest in the middle, that is to say at the location of the largest depression in the surface 11, and then rolls on both sides.

In the arrangement shown in FIG. 9, the entire stamp 1, including the pressure pad 8, is arranged on a carrier film 22 made of plastic. A hard roller 23 is assigned to the embossing die, which rolls according to the indicated arrows on the embossing die 1 when the workpiece 12 to be printed has been raised in accordance with the double arrow 16 and the embossing foil 10 comes into contact with the support mask 4 and the stamping surface 3 is. The roller 23 and the workpiece 12 can also be mounted in a stationary manner in the horizontal direction and rotatably, the stamping die 1 being moved horizontally.

Figure 10 shows a very similar embodiment. Here, only a cutting-like tool 24 is appropriately guided over the back of the stamping die 1 when the workpiece 12 has come into contact with the stamping die 1 with the hot stamping foil 10 clamped in between. The print image is here, as it were, stripped. The embodiments of FIGS. 9 and 10 can be used for flat workpieces 12 as well as for curved workpiece surfaces. FIG. 11 finally shows a possible arrangement in which a hydraulic or pneumatic power pack 25, for example an inflatable bellows or the like, is provided behind the die 1. The stamping die 1, which itself has the pressure pad 8, can also be brought into contact with this.

While in all previous embodiments of FIGS. 1 to 11 the positive force transmission relief was provided recessed, i.e. was formed by the conductor tracks or the resistance metal tracks 7 of the heating device, it is also possible to raise the force transmission relief 26 and from the rear surface of the stamp body 2 form above, as shown in the embodiments of Figures 12 to 15. In the embodiment according to FIG. 12, the embossing stamp there consists on the one hand of the stamp body 2 and on the other hand of the pressure pad 8, which is arranged on the carrier film 22. The stamp body 2 has integrated the heating device 5, which can be designed as a resistance heating element in the form of a band with a constant width or also notched in the area of the printed image. Areas made of elastic material, in particular rubber or silicone, are located on both sides of the heating device 5. provided, the stamp surface 3 being formed on the side facing the workpiece at the raised locations there. The positive force transmission relief 26 protrudes toward the rear side, that is to say toward the pressure pad 8, which is designed as positive and corresponds exactly in size and arrangement to the relief with the stamp surface 3. A rubber band can also be provided between the stamp body 2 and the pressure pad 8, but this is not shown here for reasons of clarity. When the parts are brought together for the purpose of hot stamping foil printing, the forces which are applied via the force transmission relief 26 are then supported on the pressure pad 8 on a somewhat wider basis by means of the elastic rubber band, so that the pressure pad 8 has a longer service life. There are no places formed by the power transmission relief 26 that have lost their resilience. The rubber band described can also be provided as a surface coating of the pressure pad 8.

FIG. 13 shows excerpts from the stamp body 2, namely first the heating device 5 in the form of a metal strip, on which the stamp body 2 is also handled at the same time. On both sides of the heating device 5 or the metal strip, elastic material of the same or different thickness is applied, of which z. B. can be removed with a laser engraving machine corresponding unwanted material parts, so that there are training, as illustrated in the following detailed images of Figure 13. The stamp body 2, which has the stamp surface 3, is formed as a negative on the underside facing the workpiece. The width a of the letters and lines there corresponds exactly to the width b of the letters and lines of the power transmission relief 26 in the contact area 27 with the pressure pad 8 (not shown here). On one side of the heating device is a negative and thus arranged a positive on the other side of the heating device.

However, the design can also be such that the width at the contact surface 27 of the power transmission relief 26 is selected to be larger than the width a of the letters in the stamp surface 3. Finally, the reverse design is also possible. In this way, the forces to be transmitted can be used with greater or lesser surface pressure.

The embodiment of an embossing station shown in FIG. 14 can be regarded as an alternative to the embodiment according to FIG. The pressure pad 8 is arranged on a roller 19 which is rotatable and / or variable in height, but not horizontally displaceable. The workpiece 12 to be printed with its surface 11 can also be rotated, but is non-displaceable horizontally. The stamp body 2 is here arranged on one side on a flat heating device 5, which is designed in the form of a band. On the other side is the power transmission relief 26 with the contact surfaces 27. The heating device 5, which is also used for handling, is cyclically moved back and forth according to the double arrow 28 when the printing process takes place. For this purpose, the workpiece 12 is raised and / or the roller 19 with the pressure pad is lowered until the parts come into contact with one another. The hot stamping foil 10 can be guided over rollers 29, on the one hand to bring it to the stamp surface 3 only by line contact and on the other hand to guarantee the slight cooling time until the hot stamping foil 10 detaches from the surface 11 of the workpiece 12 again. It should be noted that printing is only carried out at all points on the print image and that the cooling time is constant at all points or only from the speed of movement of the stamp body 2 depends on the double arrow 28 during the printing process. A particularly advantageous embodiment is shown in FIG. Here, too, the pressure pad 8 is located on a roller 19, around which the stamp body 2 is guided around in a closed manner on a carrier film 6. The circulating belt also extends over a deflection roller 30, which is provided vertically above the roller 19 with a parallel axis. Several uses of stamp body 2 can also be provided on the belt driven in accordance with arrow 31, so that larger numbers of workpieces can be printed with such a printing belt. The carrier film 6 can also be designed here as a heating device 5, so that the required heat is transferred to the stamp surface 3 over short distances. Since a current supply to the heating device 5 or the carrier film 6 is required in this respect, a reciprocating drive in the direction of the arrow 31 or in the opposite direction is also possible in cycles.

However, it is also possible to provide the heating device 5 outside and separately from the circulating belt. In this case, it is advisable to continuously drive the circulating belt with the stamp body 2 in only one direction according to arrow 31. The heating device 5 can then be formed from an infrared radiation source 32, which emits its heat radiation according to the arrows 33. A diaphragm 34 can be designed to be stationary or, as shown, to be a band running around rollers 35 with corresponding openings 36, which can be driven intermittently or also continuously in the direction of an arrow 37. The aperture 34 can finally also be provided to be stationary, in which case it is then expediently provided with a cooling device on its rear side so that it does not itself become a radiation source due to the irradiation with the infrared source 32. Finally, it is also possible to switch the infrared radiation source 32 to one To set the slide 38 and to drive it vertically up and down in accordance with arrow 39, in coordination with the movement of the diaphragm 34. In all these cases, it is possible to selectively pass through the diaphragm 34 and for a required or controllable time only the stamp surfaces 3 of the stamp body 2 - even when arranging several uses on the circulating belt - to expose and thus heat. This has the advantage that the heat sits directly on the surface of the stamp surface 3 and thus there is no need to travel with heat conduction. When the belt rotates around the rollers 19 and 30, the previously heated stamp surface comes into effect directly at the printing location. In this way, power control and adaptation of the heat to be transferred to the stamp surface 3 is also possible in a simple manner. The amount of heat required is extremely small, which means that heat is used sparingly and responsibly. It goes without saying that here too the force transmission relief 26 with the contact surfaces 27 to the pressure pads 8 is provided on the back of the circulating belt or the carrier film 6.

Reference symbol list:

1

= Stamp

2nd

= Stamp body

3rd

= Stamp area

4th

= Support mask

5

= Heater

6

= Carrier film

7

= Resistance metal track

8th

= Pressure pad

9

= Thermal insulation layer

10th

= Hot stamping foil

11

= Surface

12

= Workpiece

13

= Bump

14

= Width

15

= Lifting head

16

= Double arrow

17th

= Table

18th

= Connection

19th

= Roller

20th

= Spring elements

21

= Sheet steel

22

= Carrier film

23

= Roller

24th

= cutting-like tool

25th

= Powerhouse

26

= Power transmission relief

27

= Contact surface

28

= Double arrow

29

= Roller

30th

= Deflection roller

31

= Arrow

32

= Infrared radiation source

33

= Arrow

34

= Aperture

35

= Roller

36

= Breakthroughs

37

= Arrow

38

= Sledge

39

= Arrow

Claims (18)

1. Device for dry printing a workpiece using a hot stamping foil and a stamping die and with the application of heat, pressure and time, in which the workpiece and the stamping die are moved relatively to one another, held in contact with the intermediate clamping of the hot stamping foil whilst heat is transferred and are moved apart again, the hot stamping foil being adhesively bonded onto the workpiece corresponding to the stamping die and, after a cooling time, being removed from the workpiece with the exception of the printed image, with a reception station for the workpiece, a cyclically operating feed device for the hot stamping foil and a heating device for the stamping die which consists of elastically deformable material and has a die body, characterised in that the die body (2) is designed with thin walls such that when laid on the workpiece (12) to be printed it lies on the surface (11) thereof in a locally elastically deforming manner, in that the die body (2) has on its side directed away from the die face (3) a positive force transmission relief (7, 26) which corresponds to the die face (3) or is designed in a manner similar to this, and in that an elastic pressure pad (8) for local elastic deformation of the die body (2) is allocated to the die body (2) on the side directed away from the die face (3).
2. Device according to Claim 1, characterised in that the heating device (5) is provided on or in the die body (2) and is disposed in a locally limited manner corresponding to the printing image, so that the heating device (5, 7) also forms the force transmission relief (7).
3. Device according to Claim 1, characterised in that the die body (2) of elastically deformable material is provided on one side of a supporting body (5, 6) and the force transmission relief (26) of elastically deformable material is provided on the other side of the supporting body.
4. Device according to Claim 2 or 3, characterised in that the force transmission relief (26) is designed, in particular at its contact surface (27) with the pressure pad (8), in a similar manner to, and specifically the same as, smaller or larger than, the die face (3) of the die body (2).
5. Device according to Claim 3, characterised in that the heating device (5) is provided in the die body (2) between the relief having the die face (3) and the force transmission relief (26) and at the same time forms the supporting body (6).
6. Device according to Claim 3, characterised in that the die body (2) are [sic] provided with the force transmission relief (26) in the form of a reciprocally moveable sheet or of a belt which is also driven in a revolving manner (Figure 15).
7. Device according to Claim 6, characterised in that the heating device is provided outside the die body (2) and the heat transmission takes place directly to the die face (3).
8. Device according to Claim 7, characterised in that between the heating device (32) and the die face (3) of the die body (2) a mask (34) is provided, and in that the heating device and/or the mask are arranged so as to be stationary or adjustable.
9. Device according to Claim 2 or 3, characterised in that the hardness of the pressure pad (8) is matched to the hardness of the material of the die body (2).
10. Device according to Claim 9, [lacuna] that the force transmission relief (26) at its contact surface (27) is designed so as to be identical to the die face (3) of the die body (2), and in that a distribution rubber belt is provided between the contact surface (27) and the pressure pad (8).
11. Device according to Claim 9, characterised in that the pressure pad (8) provided is a hydraulic or pneumatic pad, a cushion of foam or the like.
12. Device according to Claim 2 or 3, characterised in that the heating device (5) is a circuit board with a carrier sheet (6) and a resistance-metal track (7) which is disposed thereon and corresponds to the design and arrangement of the printing image.
13. Device according to Claim 12, characterised in that a thermal insulation layer (9) of elastic material is provided between the carrier sheet (6) of the circuit board and the pressure pad (8).
14. Device according to Claim 2 or 3, characterised in that the die body (2) is designed in regions as a support mask (4).
15. Device according to Claim 14, characterised in that the pressure pad (8) is permanently bonded to the die body (2).
16. Device according to Claim 2 or 3, characterised in that the pressure pad (8) has a greater wall thickness than the die body (2).
17. Device according to Claim 16, characterised in that the pressure pad (8) consists of thermally insulating material.
18. Device according to Claim 11, characterised in that the pressure pad (8) is designed to generate a pressure of approximately 100 g/cm².

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