EP3463887B1 - Foil stamping machine - Google Patents

Description

The invention relates to a sheet-processing foil stamping machine according to the preamble of claim 1.

During hot embossing, a material layer to be embossed, for example a sheet of printing material or a sheet of printing material, is passed through an embossing gap between an embossing tool carrier device and a counter-pressure element, e.g. B. an impression cylinder or an impression plate is formed. The embossing tool carrier device carries one or more embossing tools which can be heated by means of a heating device during hot embossing. Depending on the type of embossing device, the embossing tool carrier device can, for example, have a flat shape - for so-called round-flat machines or flat-flat machines - or a cylindrical shape - for so-called round-round machines or rotary machines.

The field of application of the invention are sheet-processing foil stamping machines in round-flat technology. Here the embossing tool carrier device is formed by an embossing foundation that is guided to be linearly movable back and forth on a base frame of the machine. In round-flat machines, the embossing foundation works together with an embossing cylinder arranged with a horizontal axis of rotation above the embossing foundation.

During operation of the foil stamping machine, at least one stamping foil web is guided through the stamping gap in such a way that it has the same state of motion as the material layer to be stamped during an stamping interval. During the embossing interval, the embossing material located on the embossing film web, for example discrete embossing units such as images, texts and / or holograms, or a part of a color layer or metal layer to be embossed, is transferred to the material layer under the action of pressure and temperature.

The stamping film web is pulled off a film supply by a film transport device and moved forward. The used stamping foil is taken away and disposed of. The film transport device, which is also referred to below as the "film plant", has one or more control devices actively involved in controlling the movement of the film web, in order to precisely determine the preferred distance of the embossing film web when the film is being drawn in accordance with a control program.

The EP 2 128 060 A2 describes a sheet-processing foil stamping machine in round-flat technology. A foil storage container for receiving at least one supply roll for embossing foils is attached to the stamping foundation. A film braking device for generating web tension between the supply roll and a control device of the film factory immediately following the supply roll is designed to generate a braking force which acts directly on the stamping film web at a distance from the supply roll. The foil stamping machine works according to the so-called "one-turn principle". The embossing cylinder makes one revolution (a "tour") while the embossing foundation moves once forwards and once backwards under the embossing cylinder. The embossing process takes place in the forward movement. The backward movement of the embossing foundation takes place in the non-printing part of the embossing cylinder, in which a recess is provided on the embossing cylinder for the embossing foundation to pass through. The circumference of the embossing cylinder corresponds with the one-turn principle to the sum of the path that the embossing foundation covers in its forward and backward movement. The paper feeder and the paper delivery are on the same side of the embossing unit, one above the other.

Task and solution

The invention is based on the object of providing a generic sheet-processing foil stamping machine that can be used flexibly, can also process larger quantities of sheets without reloading, and can preferably be switched to different stamping processes with low set-up and non-productive times.

To solve this problem, the invention provides a foil stamping machine with the features of claim 1. Advantageous further developments are given in the dependent claims. The wording of all claims is incorporated into the content of the description by reference.

A special feature is that the embossing cylinder is designed as a cylinder with a first gripper bar and a second gripper bar that is circumferentially offset with respect to the first gripper bar. The embossing cylinder is thus able to simultaneously carry two sheets of printing material supplied one after the other from the system stack. For this purpose, the circumference of the embossing cylinder is dimensioned so large that behind each of the gripper bars there is a cylindrically curved jacket section which is so extended in the circumferential direction that that a complete sheet held by the leading gripper bar fits onto this jacket section.

A storage drum is assigned to the embossing cylinder for taking over and transferring sheets of printing material between the embossing cylinder and the storage drum. The storage drum rotates in the opposite direction to the embossing cylinder during operation and is mounted in the vicinity of the embossing cylinder in such a way that the sheet can be transferred directly between the embossing cylinder and the storage drum or between the storage drum and the embossing cylinder. The integrated storage drum is located in the material flow of the printing material between the system, with which fresh sheets of printing material are fed in, and the embossing process, so that the storage drum can temporarily store unprinted sheets of printing material (blank sheets). The storage drum is used to temporarily store blank sheets between the system and the embossing process.

Due to the storage drum, it is possible to arrange the feeder and the boom on opposite sides of the embossing unit. Corresponding embodiments are characterized in that a device for sheet contact and a device for sheet delivery are arranged on opposite sides of the embossing unit. In this way, compared to the prior art, significantly higher system stacks and deposit stacks can be processed, whereby productivity can be increased.

Furthermore, a height adjustment device with an actuator is provided for adjusting the height of the embossing foundation in relation to the base frame. The actuator is controlled by the control of the foil stamping machine. With the aid of the height adjustment device, pressure adjustment between the embossing cylinder and the embossing tools carried by the embossing foundation is possible. This means that an optimal pressure can be set between the printing material and the embossing tools at any time by reducing or increasing the embossing gap (distance between the embossing cylinder and the embossing tools). In addition, the "pressure on" and "pressure down" positions can be approached with the aid of the height adjustment device.

In a further development, the embossing cylinder is mounted with a fixed axis of rotation, ie not adjustable in height in relation to the base frame. In this variant it is therefore provided that the embossing gap can be set or adjusted exclusively by means of the height adjustment device for the embossing foundation. The construction on the side of the support of the embossing cylinder can be greatly simplified in comparison to solutions with height-adjustable embossing cylinders. While all variants with a height-adjustable embossing cylinder have Assemblies corresponding to the embossing cylinder, such as sheet transfers and drums, must also be adjusted, which can lead to tolerances in the sheet guide, these sources of error are avoided in this embodiment. If the embossing gap is only changed via the height-adjustable embossing foundation, the other assemblies such as embossing cylinders, sheet transfer from the system to the embossing cylinder, storage drum and delivery drum can always remain in their predetermined fixed positions. This simplifies the storage of these components.

The embossing mechanism preferably works without bearer rings and bearer bars. Such elements are known to prevent the so-called "Schmitz", that is, an error in the printing process which can manifest itself in the form of smeared prints. With the help of bearer rings, the elements that cooperate with one another (embossing cylinder and embossing foundation) can be forcibly guided to one another via frictional engagement, in order to enable a process that is in register.

In embodiments without bearer rings and bearer bars, the circumferential speed of the embossing cylinder can be adjusted independently of the movement speed of the embossing foundation, if necessary steplessly while the machine is running. This allows the print length to be changed continuously. In some embodiments, such a device is provided for changing the printing length in both directions (increasing the printing length or reducing the printing length).

In some embodiments, this is implemented in that a stamping foundation drive is provided for generating the working movement of the stamping foundation, the stamping foundation drive being controllable independently of a rotary drive for the stamping cylinder. In this way a device for changing the printing length can be realized.

The stamping foundation drive preferably has a servomotor or an electrical direct drive, for example a linear drive. If a servomotor is provided, this can drive a threaded spindle on which a spindle nut runs, which is connected to the stamping foundation. Compared to conventional drives using crankshafts, etc., significantly higher production outputs can be achieved, among other things, due to the lower mass. The speed of movement of the embossing foundation can be changed by controlling the embossing foundation drive in relation to the circumferential speed of the embossing cylinder so that the print image can be lengthened or shortened. Adjustment while the machine is running is possible.

In a further development, the embossing foundation can be moved by means of the embossing foundation drive from a pressure movement area assigned to the embossing cylinder into a maintenance area remote from the embossing cylinder. With these variants, the separate stamping foundation drive makes it possible to move the stamping foundation separately while the machine is at a standstill and, for example, to move to a change position. This position is an extension of the travel distance of the stamping foundation required for stamping, but outside of this travel range.

The change position is preferably arranged in such a way that the complete embossing foundation with all embossing tools can be removed from the side of the foil stamping machine or inserted into the foil stamping machine. The complete embossing form can be exchanged for another and individual embossing tools can be adjusted. This variant reduces set-up and non-productive times.

The height adjustability of the embossing foundation can be implemented in different ways. A particularly robust construction is characterized in that the embossing foundation is guided to and fro linearly on a support frame by means of linear guides and that the support frame is pivotably mounted on the base frame of the foil stamping machine, a pivot axis of the support frame being arranged at a lateral distance from the embossing gap. It would also be possible to design the construction in such a way that the stamping foundation is displaced perpendicular to the plane of movement used during productive operation by parallel displacement; a pivoting or tilting is, however, particularly easy to implement structurally.

The stamping foundation drive is preferably mounted on the support frame so that it can move with it.

The foil unit is preferably configured to generate a discontinuous movement of the foil web with retraction phases. This can minimize the film consumption.

The film transport device, which is also referred to as "film factory" in the following, can for example have one or more control devices actively involved in controlling the film web movement in order to precisely determine the preferred path and the movements of the embossed film web when the film is drawn in accordance with a control program. In one embodiment, the active control devices include one or more so-called timing rollers (or control rollers) which are in slip-free rolling contact with the The embossing film web is available and its angle and direction of rotation can be precisely controlled, as well as a pulling device with a slip drive. The timing rollers (control rollers) and the pulling device are located on opposite sides of the embossing gap. In addition to the active control devices, a number of passive devices, for example deflection rollers and / or air deflection rods, are generally provided in the foil plant in order to determine the course of the stamping foil web (s) through the foil plant.

The new type of embossing unit can be used in combination with differently designed foil units. For example, it is possible to design the film work as it is in the EP 2 128 060 A2 is described. Variants according to the DE 3713666 A1 or the EP 0 718 099 A2 or the EP 1 155 831 A2 are possible. The disclosure content of these documents is made part of this description by reference.

Brief description of the drawings

• Fig. 1 zeigt eine schematische Seitenansicht einer Ausführungsform einer Bogen verarbeitenden Folienprägemaschine;
• Fig. 2 bis 5 zeigen Komponenten der Folienprägemaschine in vier zeitlich aufeinanderfolgenden Phasen während des Prägebetriebs.

Further advantages and aspects of the invention emerge from the claims and from the following description of preferred exemplary embodiments of the invention, which are explained below with reference to the figures.

• Fig. 1 shows a schematic side view of an embodiment of a sheet-processing foil stamping machine;
• Figs. 2 to 5 show components of the foil stamping machine in four successive phases during the stamping operation.

Detailed description of the exemplary embodiments

Figure 1 shows a schematic side view of an embodiment of a sheet-processing foil stamping machine 100 in round-flat technology. The foil stamping machine 100 has an embossing unit 110. The embossing unit comprises an embossing foundation 130 which is guided essentially horizontally movably on the base frame 120 of the machine and which can also be referred to as a tool slide, as well as an embossing cylinder 140, which has a horizontal axis of rotation 141 above the base frame and the embossing foundation is arranged and serves as a counter pressure element. The embossing cylinder can also be referred to as a printing cylinder.

An embossing gap 145 is temporarily formed between the embossing foundation 130 and the embossing cylinder 140 during operation of the foil embossing machine when the embossing foundation is located below the embossing cylinder 140 during its horizontal linear back and forth movement.

The embossing unit also includes a storage drum 150 mounted axially parallel to the embossing cylinder, which rotates in the opposite direction to the embossing cylinder and is arranged with its largely cylindrical outer surface so close to the outer surface of the embossing cylinder that printing material sheets can be transferred and accepted directly between the embossing cylinder 140 and storage drum 150.

The embossing cylinder 140 is mounted with a fixed axis of rotation 141, i.e. not adjustable in height in relation to the base frame, in side walls of the base frame 120, not shown in detail. The construction of the embossing cylinder bearings can thereby be greatly simplified in comparison to solutions with height-adjustable embossing cylinders. The embossing cylinder 140 is driven by an electric rotary drive, not shown, which is connected to the control unit of the foil embossing machine and rotates the embossing cylinder around the axis of rotation 141 at a constant rotational speed during operation, so that it is a single-turn system.

The embossing cylinder 140 is designed as a cylinder with a first gripper bar 142-1 and a second gripper bar 142-2, which is circumferentially offset from the first gripper bar, and works together with the storage drum 150 for guiding the sheets, which in the running direction of the sheets is guided between the feed cylinder 166 and the Embossing gap 145 is arranged. Details are given in connection with the Figures 2 to 5 explained in more detail.

The embossing foundation 130 is provided to carry exchangeable embossing tools (types) on its upper side facing the embossing cylinder 140. A heating device is integrated into the stamping foundation, which makes it possible to heat the stamping tools to temperatures well above 100 ° C, preferably above 200 ° C, during operation.

The embossed foundation 130 can be moved linearly back and forth in a sliding plane by means of a group of several parallel linear guides on a support frame 134. Instead of roller guides that are also possible, guide elements are slidably guided on the underside of the stamping foundation on straight guide elements on the support frame.

The support frame 134 is mounted on the base frame 120 such that it can be pivoted steplessly. The horizontal pivot axis 136 of the pivot bearing is located in FIG Fig. 1 below the sliding plane at the right end of the support frame on the side of the stack of systems at a relatively large distance from the embossing gap, this distance being greater than the travel that the embossing foundation covers during an embossing interval. By pivoting the support frame 134 about the pivot axis 136, the sliding plane of the embossing foundation can be brought from the illustrated horizontal orientation into a tilted position inclined relative to the horizontal. A maximum tilt angle is a few degrees, for example a maximum of 2 degrees to a maximum of 5 degrees. It can be seen that by pivoting the support frame 134 with respect to the base frame, the size (or height) of the embossing gap 145 can be adjusted continuously.

The pivoting movement is carried out with the aid of an actuator 138 which engages in the end region of the support frame opposite the pivot axis at a greater distance from the embossing gap on the underside of the support frame. The actuator, which operates pneumatically, for example, is connected to the control unit of the foil stamping machine and can be controlled by this during operation of the machine or during stamping breaks. With the aid of the actuator, the embossing gap, i.e. the distance between the embossing cylinder and the embossing tools, can be reduced or enlarged by pivoting the support frame in order to set the optimum pressure between the printing material and the embossing tools for the embossing process. This pressure setting is possible when the machine is running. In addition, the actuator can be used to move to the predeterminable positions "pressure on" and "pressure down". In the "pressure on" position, the sliding plane of the stamping foundation runs essentially horizontally and a hot stamping process is possible. In the "print off" position, the sliding plane is inclined slightly (a few degrees) to the horizontal and the embossing foundation is out of engagement with the embossing cylinder.

The pivotable support frame 134 and the actuator 134 provided for setting the pivot position are functional components of a height adjustment device for adjusting the height of the embossing foundation in relation to the base frame 120. The embossing gap is changed here exclusively via the height adjustment (here: pivoting) of the embossing foundation. The subassemblies used to guide the sheet, in particular the embossing cylinder 140, the storage drum 150 and the cylinders on the system side and the boom side, are stored in non-height-adjustable bearings and thus always remain in their fixed positions. This enables sheet guidance that is stable over the long term and is accurate in register. The embossing foundation 130, which can be moved linearly back and forth, is moved with the aid of an embossing foundation drive 132 in the form of an electric servo motor, which can be controlled independently of the rotary drive of the embossing cylinder 140 by the control unit of the foil stamping machine. The servomotor drives a threaded spindle 133 mounted in the support frame 134, on which a spindle nut runs, which is fastened to the underside of the embossing foundation 130. In other embodiments, an electric linear drive can be provided instead, which includes, for example, a stator that is permanently installed in the support frame and a rotor that is fastened to the stamping foundation. This drive concept has a significantly lower weight than conventional drives with crankshafts etc. and thus enables higher production outputs.

Since the embossing foundation drive 132 can be controlled independently of the rotary drive for the embossing cylinder 140 and the embossing cylinder and the embossing foundation are not in engagement with one another via bearer rings or the like, the movement speed of the embossing foundation can be changed in relation to the circumferential speed of the embossing cylinder if necessary so that an extension or shortening of the printed image is possible. Such an adjustment is possible while the machine is running by activating the drives for the embossing foundation and the embossing cylinder accordingly. The entire travel path of the embossing foundation can be corrected variably so that the travel path can be adapted to the respective printing length. The control can be implemented in such a way that there is no unnecessary travel, whereby improved production speeds can be achieved.

The separate drive for the embossing foundation also makes it possible to move the embossing foundation separately from an, for example, stationary embossing cylinder when the machine is at a standstill. For example, this can be used to move to a change position which, in extension of the travel distance of the embossing foundation required for embossing, lies outside the printing travel path required for this. In the example of Fig. 1 the change position is to the left of the embossing cylinder under the delivery system 190. In the example, the change position is arranged in such a way that the entire embossing foundation with all embossing tools can be removed from the side of the machine or inserted. The entire embossing foundation can be exchanged for another, or individual embossing tools can be exchanged and / or adjusted. Such a design reduces set-up and non-productive times.

The material sheets to be printed are held on a supply stack or feed stack 162 shown on the right with the side to be embossed facing up. The arches are in Operation of the foil stamping machine is fed individually to the stamping cylinder 140 of the stamping unit via an inclined feed table 164 and a feed cylinder 166.

A gripper bar of the embossing cylinder grasps the front edge of a sheet and pulls the sheet onto the jacket section of the jacket surface that lies behind the gripper bar. During the gripping process, the sheets of printing material are aligned. An empty sheet is then temporarily stored, which will be explained in greater detail later. Each sheet is later guided through the embossing gap 145 from left to right in the direction of rotation (arrow) of the printing cylinder shown during an embossing interval and embossed in the process. When passing through the embossing gap (from left to right in the figure), the surface of the sheet of material to be printed has a speed that (depending on the sheet's material thickness) essentially corresponds to the circumferential speed of the sheet-bearing surface of the continuously rotating embossing cylinder. After the embossing interval, the embossed sheet of material is transferred to the delivery system 190, which conveys the printed sheets of material one after the other via a delivery cylinder 196 and a partially inclined delivery section 194 to a storage stack 192, which is located on the side of the embossing unit 110 opposite the stack 162.

In the following, special features of the sheet guidance are explained using the Figs. 1 to 5 explained in more detail. As already mentioned, the embossing cylinder 140 is designed as a cylinder with two circumferentially offset gripper bars and works together with a storage drum 150. The Figs. 2 to 5 show these two elements together with the feed cylinder 166 on the plant side and the delivery cylinder 196 on the boom side in four successive phases during the embossing operation.

The embossing cylinder 140 has two gripper bars running parallel to the axis of rotation 141 on the outer circumference of the embossing cylinder, namely a first gripper bar 142-1 and a second gripper bar 142-2 diametrically opposite to the axis of rotation 141. The first gripper bar 142-1 is followed by a cylindrically curved first jacket section 144-1, which is extended in the circumferential direction so that a complete sheet held by the leading first gripper bar fits onto this first jacket section. In the situation in Fig. 1 a first sheet B1 is held at its leading edge in the first gripper bar 142-1 and rests on the first jacket section 144-1. The first jacket section 144-1 is that jacket section with which the embossing cylinder can come into engagement with the embossing foundation 130 during the embossing interval; it is therefore also referred to here as the “pressure section”.

Behind the second gripper bar 142-2 diametrically opposite the first gripper bar 142-1 is a cylindrically curved second casing section 144-2 whose radial distance from the axis of rotation is smaller than the radial distance from the first casing surface 144-1 to the axis of rotation, for example by 4 mm up to 5 mm smaller. A sheet held by the second gripper bar 142-2 can rest over the entire surface of the second jacket section. The second jacket section is used, among other things, for transporting the sheets between the contact cylinder 166 and the storage drum 150 and is therefore also referred to here as the “transport section”.

Figure 2 shows the embossing mechanism 110 in an operating phase in which an already printed first sheet B1 is transferred from the first jacket section 144-1 via the delivery cylinder 196 to the delivery. In this phase, a second sheet B2 drawn from the feeder after the first sheet is located on the circumference of the storage drum 150, which has its own gripper bar 152 for accepting sheets from the embossing cylinder 140. The diameter of the storage drum is dimensioned so that exactly one sheet fits onto the cylindrical surface of the storage drum outside the recess for the gripper bar. A third sheet B3 (blank sheet) is being fed to the embossing cylinder 140 by means of the contact cylinder 166. Its leading edge is being gripped and aligned by the second gripper bar 142-2. The embossing foundation 130 is at this point in time in the starting position shown on the left and waits for the start of printing to emboss the second sheet B2.

Fig. 3 shows the embossing mechanism 110 after the embossing cylinder 140 is opposite the in Fig. 2 shown starting situation by half a turn counterclockwise. The third sheet (blank sheet) B3 now lies completely on the second casing section 142-2 and is immediately before the transfer to the storage drum 150. The second gripper bar 142-2 is just transferring the third sheet to the gripper bar 152 of the storage drum. The second sheet B2, which is in the in Fig. 2 The phase shown is still on the storage drum 150, has meanwhile been gripped by the first gripper bar 142-1, brought onto the first casing section 144-1 and conveyed through the embossing gap 145, while the embossing foundation 130 is moved from its starting position in a forward movement towards the end position . During this embossing interval, the circumferential speed of the first jacket section 144-1 corresponds to the movement speed of the embossing foundation.

In Fig. 4 the embossing mechanism 110 is shown after a further half rotation of the embossing cylinder 140. The second sheet B2, which has meanwhile been completely embossed, is released by the first gripper bar 142-1 and a section running ahead has been taken over in the direction of the display by means of the delivery cylinder 196. At the same time as this handover of the printed In the sheet from the embossing cylinder to the delivery, a fresh blank sheet (fourth sheet B4) is transferred from the system to the second jacket section 144-2 of the embossing cylinder, i.e. to the jacket section with the smaller radius, at the contact cylinder 166. This jacket section is used to transport from the feeder to the storage drum 150. For this purpose, the front edge of the fourth sheet is gripped by the second gripper bar 142-2. The third arc B3, which is made during the phase Fig. 2 has just been drawn onto the embossing cylinder, has meanwhile been transported to the storage drum 150 and has been completely transferred to it. The leading edge of the third sheet B3 is being transferred from the gripper bar 152 of the storage drum to the first gripper bar 142-1, which will pull the third sheet onto the printing section (first jacket section 144-1) in the subsequent phase. During this phase, in which there is no sheet in the area of the embossing gap, the embossing foundation 130 moves from its end position on the right back to the start position on the left after the embossing interval has ended. This retraction movement is possible without touching the embossing cylinder, since in this phase the transport section (second casing section 144-2) lies with a smaller radius opposite the travel path of the embossing foundation.

Fig. 5 shows the embossing mechanism 110 after a further rotation of the embossing cylinder 140 by approx. 45 ° with respect to FIG Fig. 4 situation shown. The third arch B3, which is in Fig. 4 was still completely held on the jacket surface of the storage drum, has now been gripped by the first gripper bar 142-1 and has already been partially pulled onto the trailing first jacket section 144-1, ie the pressure section. After a further quarter turn, the area of the front edge of the third sheet B3 will get into the embossing gap and be embossed.

The embossing cylinder thus has two gripper bars that are circumferentially offset by 180 ° from one another. A second gripper bar 142-2 takes over a sheet from the system and transports it for transfer to the storage drum 150. The storage drum makes one revolution and then transfers the sheet to the first gripper bar 142-1. In the meantime, the embossing cylinder 140 has rotated 180 °. The first gripper bar 142-1 transports the sheet during the embossing interval through the embossing gap, where the sheet is embossed, and from there on to the delivery gripper bridge. Then the next sheet is removed from the storage drum by the first gripper bar and so on.

During operation of the foil stamping machine, at least one stamping foil web 170 is moved through the stamping gap 145. Those devices that guide the stamping foil web and control the preferred movement of the stamping foil web belong to the so-called foil plant 180 of the foil stamping machine. The embossing foil web is usually very thin (between 10 µm and 20 µm) and usually consists of a relatively tough plastic carrier film, on the front of which is a layer system with a thermally activated separating layer, the actual embossing layer (e.g. color layer or metal layer or hologram or individual images ), and a thermally activatable hot-melt adhesive layer is applied, which forms the front side of the embossing film web facing the printing material.

During an embossing interval, the embossing film web runs at the same speed as the sheet of material to be printed through the embossing gap 145. For this purpose, the linearly movable embossing foundation 130 is moved from its starting position shown in the figure (cf. Fig. 1 ) accelerated to the left of the embossing cylinder so that the embossing tools also have the same speed during the embossing interval as the sheet of material to be embossed and the sheet of embossing film guided between the sheet of material and the embossing tool. During the embossing interval (e.g. Fig. 3 ) the embossing unit (for example part of a layer of paint) is transferred to the sheet of material under the influence of pressure and temperature. After the embossing foundation was moved in the forward movement during the embossing interval synchronously with the sheet of material and the embossing foil web, it is braked after the embossing interval has ended until it reaches the end position on the right. The return of the embossing foundation to the starting position (vg. Fig. 4 ) is possible without contact with the embossing foil web or the embossing cylinder.

During the forward movement (from left to right) and during the subsequent return movement, the foil is pulled by a predeterminable preferred distance that is dependent on the motif. The foil feed is controlled by timing rollers of the foil plant, which for this purpose rotate by a predefinable angle of rotation. A length compensation takes place with the help of a film storage unit in order to guarantee sufficient web tension at all times.

The foil work 180 of the embodiment of Fig. 1 can run several adjacent embossing foil strips in parallel. The foil unit 180 allows an embossing foil web outside the embossing interval to be guided more slowly than the material layer to be embossed, to accelerate it to material layer speed before the embossing interval and then to decelerate it again and move it against the main transport direction (in Fig. 1 from left to right, see arrow) in a withdrawal phase. This discontinuous film web movement with retraction phases enables the transferred embossing units or ink layer areas to be arranged directly one after the other on the embossing film web, even if the embossing locations on the printing material are significantly further apart, which can minimize film consumption. Each stamping film web is fed from a supply roll 182-1, 182-2 shown on the left (the supply rolls are arranged in two different levels) through a vacuum film loop storage device 183 via a so-called timing roller or control roller 184 (in the example timing rollers are arranged in four levels one above the other) , which represents the "zero point" of the film web movement within the system of the film factory. The stamping film web is fed from the associated cycle roller via passive deflection devices (e.g. air bars or blowpipes and / or deflection rollers) in the direction of the embossing gap 145 and from there via several passive deflection devices (e.g. air rods or blowpipes and / or deflection rollers) guided to a pulling device 185 with a suction roll, which rotates clockwise, so that the circumferential surface of the suction roll wrapped by the embossing film web (wrap angle, for example, between 130 ° and 180 °) moves in the main transport direction. Downstream of the suction roll, the stamping film webs are guided through a further vacuum film loop storage device 186 in the direction of the downstream disposal device. In the example, the stamping film webs are rolled up on take-up rollers 187 and then disposed of. Other disposal concepts, e.g. according to DE 10 2008 011 493 A1 are possible.

The clock rollers or control rollers 184 arranged upstream of the embossing gap can be controlled with the help of suitable electric motor drives with regard to the direction of rotation and the rotational speed, i.e. they are suitable for forward-reverse operation, and belong to the active control devices of the foil unit 180 an area wrapped around by the film web with perforations through which a vacuum can be generated by means of a suction fan, which reliably pulls the wrapping film web section onto the circumference of the suction roll, so that a rolling contact with static friction is ensured without any slip. As an alternative or in addition to suction, the non-slip rolling contact can also be ensured by means of pressure rollers or inflation or the like. The control rollers 184 cooperate with the suction roller of the pulling device 185, which rotates continuously in the main transport direction, downstream of the embossing nip, in order to ensure sufficient web tension in the useful area in between and to precisely control the film web speed and direction. For this purpose, the suction roller connected downstream of the embossing gap is operated as a pulling device 185 with a slip drive, which continuously exerts a pulling force on the at least one embossing film web guided over it in the direction of the downstream film loop storage device 186. The tensile force is large enough to ensure the web tension in the embossing nip and to enable the embossing film web to be transported back when the control rollers or timing rollers 184 rotate counterclockwise, that is, in the reverse transport direction. The pulling force generated by the slip drive however, it is not sufficient to overcome the static friction built up between the embossing film web and the clock roller circumference, so that the position of the embossing film web and its web speed are determined exactly by the rotational position and speed of the clock roller 184.

During operation of the device, the above-described discontinuous movement of the embossing film web with retraction phases through the embossing gap is brought about by the interaction of the timing rollers 184 arranged upstream of the embossing gap with the traction device 185 with slip drive (suction roll) arranged downstream of the embossing gap. Since the unused web of stamping film is fed from the continuously rotating supply rolls 182-1, 182-2 at the same time, the filling level of the vacuum film loop storage device 183 changes, which is partially emptied in acceleration phases with rapid advance of the stamping film web and continues in braking phases and in retraction phases of the stamping film web fills. The film loop storage unit thus decouples the side of the continuous film inlet from the area of the discontinuous film web movement between the slip-free control rollers 184 and the downstream slip drive 185.

A reverse arrangement of timing rollers and pulling device, that is to say a pulling device with slip drive in front of the embossing gap and controllable, slip-free timing rollers downstream of the embossing gap, is also possible.

Claims (10)

1. Sheet-processing foil stamping machine (100) having:

   a main frame (120),

   a stamping unit (110) which is supported by the main frame and which comprises a form bed (130) that is movable in a linear reciprocating manner, and a stamping cylinder (140) that has a horizontal rotation axis and is disposed above the form bed, and

   a foil unit (180) having control installations for transporting at least one stamping foil web (170) through a stamping gap (145) that during a stamping interval has been formed between the form bed and the stamping cylinder,

   characterized in that

   the stamping cylinder (140) is configured as a cylinder having a first gripper strip (142-1) and a second gripper strip (142-2) which is circumferentially offset in relation to the first gripper strip,

   wherein a cylindrically curved shell portion (144-1, 144-2) exists behind each of the gripper strips (142-1, 142-2), said shell portion in the circumferential direction being elongated such that a complete sheet that is held by the leading gripper strip (142-1, 142-2) fits onto said shell portion, wherein a first shell portion (144-1) adjoining the first gripper strip (142-1) acts as a printing portion by way of which the stamping cylinder (140) during the stamping interval can engage with the form bed (130), and the second shell portion (144-2) adjoining the second gripper strip (142-2) has a smaller radial spacing to the rotation axis of the stamping cylinder (140) than the first shell portion (144-1) and is utilizable as a transport portion;

   the stamping cylinder is assigned an accumulator drum (150) which is provided with a dedicated gripper strip (152) for acquiring and transferring print material sheets (B1, B2, B3) between stamping cylinder (140) and accumulator drum (150),

   wherein the accumulator drum (150) is configured for temporarily storing clean sheets between feed and stamping procedure, wherein the diameter of the accumulator drum (150) is dimensioned such that one sheet fits onto the cylindrical shell face of the accumulator drum (150) outside the clearance for the gripper strip (152); and

   a height adjustment installation having an actuator (138) for adjusting the height of the form bed (130) in relation to the main frame (120) is provided.
2. Sheet-processing foil stamping machine according to claim 1, characterized in that an installation for feeding sheets and an installation for delivering sheets are disposed on opposite sides of the stamping unit (110).
3. Sheet-processing foil stamping machine according to claim 1 or 2, characterized in that the stamping cylinder (140) is mounted so as to have a rotation axis (141) that is fixed in relation to the main frame (120).
4. Sheet-processing foil stamping machine according to any of the preceding claims, characterized by an installation for enlarging or reducing the printing length, wherein the installation is preferably utilizable in a stepless manner with the foil stamping machine running.
5. Sheet-processing foil stamping machine according to any of the preceding claims, characterized by a form bed drive (132) for generating operational movements of the form bed (130), wherein the form bed drive is controllable independently of a rotary drive for the stamping cylinder (140), wherein the form bed drive (132) preferably has a servomotor or an electric direct drive.
6. Sheet-processing foil stamping machine according to claim 5, characterized in that the form bed (130) by means of the form bed drive (132) is displaceable from a printing movement region that is assigned to the stamping cylinder (140) to a maintenance region that lies so as to be remote from the stamping cylinder, wherein the maintenance region is preferably disposed such that the form bed, complete with all stamping tools, is laterally retrievable from the foil stamping machine or is laterally insertable into the foil stamping machine.
7. Sheet-processing foil stamping machine according to any of the preceding claims, characterized in that the form bed (130) by means of linear guides is guided so as to be movable in a linear reciprocating manner on a support frame (134), and in that the support frame is mounted so as to be pivotable on the main frame of the foil stamping machine, wherein a pivot axis (136) of the support frame is disposed with a lateral spacing to the stamping gap (145).
8. Sheet-processing foil stamping machine according to claim 7, characterized in that a form bed drive (132) is installed on the support frame (134) for generating operational movements of the form bed (130).
9. Sheet-processing foil stamping machine according to any of the preceding claims, characterized in that the foil unit (180) is configured for generating a discontinuous foil web movement having retraction phases.
10. Sheet-processing foil stamping machine according to any of the preceding claims, characterized in that the foil unit (180) has one or a plurality of active control installations that actively participate in controlling the foil web movement so as to determine the advancing distance and the movements of the stamping foil web (170) in the foil advancement according to a control program, wherein the active control installations have one or a plurality of cycle rollers (184) which contact the stamping foil web (170) in a slippage-free rolling manner and are controllable in terms of rotation angle and rotation direction, wherein the cycle rollers interact with a traction installation (185) having a slip drive, wherein the cycle rollers and the traction installation are disposed on opposite sides of the stamping gap (145).

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