FLAT EMBOSSING PRINTING MACHINE WITH A FOIL GUIDE AND TRANSPORT DEVICE

Description

[0001] The invention lies in the technical field of flatbed stamping machines and relates to a flatbed stamping machine for stamping a flat material with a foil web guiding and transport device for at least one stamping foil web, which is guided over the stamping table of a flatbed press according to the preamble of claim 1.

[0002] With such flatbed embossing machines, which are also called flatbed embossing machines, particularly high embossing outputs can be achieved in the best quality and also for demanding embossing tasks.

[0003] Flat foil stamping machines therefore place particularly high demands on the guiding and precise foil feed of thin, narrow and very sensitive foil webs, especially hologram foil webs, and on the precise guiding and positioning of the flat material.

[0004] If the flat foil stamping machine includes a foil web guiding and transport device for several stamping foil webs, then several stamping foil webs of different types (with different web widths, preferred lengths and with different release forces after stamping) must be guided and transported smoothly and simultaneously.

[0005] The foil feed must be perfectly smooth and even, without distortion, kinking, creases, or misalignments, and positioned correctly, especially with accurate registration. The rapid, intermittent advancement of the stamping foil web must be executed with optimal care to achieve both high throughput and high quality.

[0006] Such flat embossing printing machines with foil web guiding and transport devices are known, for example, from EP 1 593 503, WO 2009 / 143644, EP 0 858 888 and EP 3 227 117.

[0007] Publication US 2014 / 053971 A1 also describes a flat embossing printing machine of this type. At the exit of the embossing table, a release element in the form of a deflection and release bar is arranged, along which the carrier film is deflected upwards after the embossing process.

[0008] For demanding image embossing tasks, especially for hologram embossing with image security features, e.g. for security notes, identity cards or banknotes, with one or more embossing foil webs across the entire embossing table, not only must optimal, error-free positioning of foil webs and flat material be achieved, but above all, gentle, flawless separation of the carrier foil webs from the flat material during further transport after embossing.

[0009] A foil stamping web typically has a thickness of only 12 to 20 µm (0.012 to 0.02 mm). It comprises a carrier film or web, which is usually made of plastic, such as polyester. The carrier film serves as the base and transport medium for the other layers or image elements, also called stamping images. The image elements or stamping images to be transferred to the flat material are applied to the carrier film web via a release liner. The image elements are characterized by their optically effective properties. The image elements can contain or consist of metal and / or color layers.

[0010] The graphic elements can be, for example, in the form of security strips or patch strips for securities such as banknotes. Accordingly, the embossing foil webs can be in the form of foil strips. Typical widths of security strips are, for example, 8–12 mm. Typical widths of patch strips are, for example, 15–22 mm. The graphic elements can be, in particular, holograms.

[0011] The release layer is a bonding and release layer of minimal thickness, typically composed of wax-like substances. Its purpose is twofold: firstly, to hold the image elements to the carrier film, and secondly, to allow the undamaged removal of the image elements from the carrier film after the embossing process. This is generally achieved by melting or softening the release layer during the embossing process under the influence of pressure and / or heat.

[0012] The carrier film web, and therefore also the image elements, is coated on the embossing side with an activatable adhesive layer. This activatable adhesive layer consists, for example, of a heat-activated adhesive or radiation-curing plastic applied across the entire surface. The heat from the embossing tool (embossing die) or subsequent radiation activates this layer, bonding the image elements to the flat material. The image elements transferred to the flat material form a permanent adhesive bond with it via the activated adhesive layer.

[0013] Radiation-cured adhesive coatings typically exhibit a two-stage adhesion process. During the embossing process, these coatings develop a primary adhesion generated by heat. In a second step, following the embossing process, the adhesive coating is activated downstream of the flatbed press by appropriate irradiation (e.g., UV radiation), resulting in a permanent, secondary adhesion through a chemical reaction.

[0014] Depending on the design of the release layer, the carrier film web can be removed from the embossed image elements more or less easily after the embossing process. Poor removal behavior is particularly common with embossing foil webs with radiation-curing, especially UV-curing, adhesive layers.

[0015] UV-cured adhesive layers of stamping foil webs wound onto unwind rolls tend to adhere to the reverse side of the carrier film adjacent to the unwind roll, the side facing away from the stamping surface. This necessitates strengthening the adhesive properties of the release liner between the carrier film and the image elements to prevent the image elements from detaching from the carrier film and adhering to the adhesive layer on the reverse side of the adjacent carrier film when the stamping foil web is unwound from the unwind roll.

[0016] In flatbed stamping machines, the removal of the carrier film web from the flat material is usually achieved by means of push separation, whereby the flat material is transported away from the flatbed press along a linear transport path, for example by means of a beam gripper, while the stamping foil web is guided away from the flat material at an angle upwards as part of the foil feed following the flatbed press.

[0017] To prevent the flat material or sheets from being lifted upwards by the still adhering embossing foil web during shear separation, vacuum devices can be provided on the embossing table, which hold the sheets on the embossing table by means of vacuum pressure and only allow the flat material to move away from the embossing table in a level manner.

[0018] If the foil web does not release properly after embossing, it remains adhered to the flat material longer than intended or desired. This deforms, overstretches, and damages the carrier film. Furthermore, the sheet becomes deformed, uneven, and warped because it is not transported flat in the intended direction but is deflected upwards by the adhering carrier film. Creases can even form in the sheet. This results in defective and unusable embossed products when the flat material is subsequently cut.

[0019] It is therefore an object of the present invention to propose a modified foil web guiding and transport device for flat foil stamping machines, which enables better and safer separation of the foil web and the flat material after stamping, even with separating layers with stronger adhesive properties, and thus enables error-free guiding of the foil web and the flat material after stamping, so that the flat material is not unexpectedly deflected and deformed by the foil web and the at least one foil web is not overstretched and damaged.

[0020] This problem is solved according to the invention by a flat embossing printing machine with a foil web guiding and transport device according to independent claim 1 and by a method according to independent claim 12.

[0021] The dependent claims relate to advantageous further developments of the invention with further improvements to the foil web guiding and transport device and to the positioning of the at least one embossing foil web and thus also to the machine performance and image quality.

[0022] The flat embossing machine for embossing a flat material includes: a flatbed press comprising an embossing table and a tool plate, a foil web guiding and transport device for guiding at least one embossing foil web along a foil transport web over the embossing table of the flatbed press, a flat material guide for guiding a flat material along a flat material transport web through the flatbed press, and a control device for operating the flat embossing printing machine.

[0023] The invention is characterized in that the film web guiding and transport device, viewed in the transport direction of the flat material, includes, following the flatbed press, a peeling element arranged above the flat material transport web and behind the film transport web for retaining and peeling the embossing film web from the flat material during the transport of the flat material out of the flatbed press.

[0024] The embossing foil web is guided through the flatbed press, particularly above the flat material. Accordingly, the peeling unit is positioned above the flat material transport web.

[0025] The flat material transport path describes the route that the flat material travels in the flatbed stamping press. Similarly, the foil transport path describes the route that the stamping foil web travels in the flatbed stamping press.

[0026] The foil web guiding and transport system of the flatbed stamping press includes, in particular, a foil feed device, specified in more detail below, for feeding the at least one stamping foil web to the flatbed press, and a foil guide device, also specified in more detail below, for guiding the at least one stamping foil web away from the flatbed press. The foil web guiding and transport system includes, in particular, a foil feed device, such as a feed roller or feed roller pair, for applying foil feed to the flatbed press. The foil feed device is, in particular, arranged within the foil guide device.

[0027] A foil web for stamping is a film or foil with at least one image element or design to be stamped, which is fed through a flatbed press. The foil web is fed through the flatbed press continuously, for example, from roll to roll.

[0028] The at least one image element or embossed image can be a uniform layer, such as a metal or color layer. The at least one image element or embossed image can completely or partially cover the carrier film.

[0029] The at least one image element or embossed image can also feature a pattern or structure. These can be created, for example, by different colors, materials, or layer thicknesses. The at least one image element or embossed image is characterized in particular by an optical effect emanating from it. The at least one image element or embossed image can, in particular, be a hologram. The at least one image element or embossed image can, in particular, be a security feature for, for example, securities such as banknotes.

[0030] The foil sheet contains several image elements or embossing designs. Such a foil sheet is also called a foil image sheet. The image elements or embossing designs can completely cover the carrier sheet. In this case, the image elements or embossing designs are adjacent to each other. Alternatively, the image elements or embossing designs can only partially cover the carrier sheet. In this case, the foil sheet also forms areas that are not covered by image elements or embossing designs. For example, the image elements or embossing designs can be spaced apart from each other on the carrier sheet.

[0031] The foil web is usually supplied as a roll and is transported from an unwind roll as part of the foil feed device through the flatbed press to a rewind roll as part of the foil guide device of the flatbed stamping machine.

[0032] For the sake of simplicity, the term "embossing foil web" is used throughout this disclosure to refer both to the foil web before and after the embossing of the image elements. This also takes into account the fact that not all images on the embossing foil web are necessarily embossed in a single embossing pass.

[0033] The flat foil stamping machine can be designed to stamp one or more foil webs, particularly those guided parallel to one another over the stamping table, onto the flat material simultaneously. For the sake of simplicity, the description of the invention refers to a single foil web at a time. However, this does not preclude the simultaneous processing of several foil webs on a single flat material. Accordingly, the device and method features according to the invention can also be applied to other foil webs in the same flat foil stamping machine.

[0034] The flat material is typically paper or cardboard. This material can be in the form of sheets, which are individually transported into the flatbed press, embossed with image elements, and then transported out of the press. The sheets can be transported by grippers, such as gripper bars, which grasp the sheets at their leading edge and pull them along a sheet conveyor through the flatbed press in the direction of travel.

[0035] The sheets can be pulled individually from a stack in a feeder. After the embossing process, the embossed sheets can be placed on a stack of sheets in a delivery unit.

[0036] However, it is also conceivable that the flat material is in the form of an endless web fed through the flatbed press. In this case, the flat material can be supplied as coiled stock and transported from an unwinding reel through the flatbed press to a winding reel.

[0037] The flatbed press is characterized by the formation of a flat or even embossing area. Because both the die plate and the embossing table are flat in the flatbed press, it is also referred to as a flat-flat press.

[0038] The flat material transport track runs in a track section directly adjacent to the flatbed press and extending to the peeling element, in particular linearly and especially horizontally.

[0039] The flat material transport path runs below the peeling organ, primarily linearly and especially horizontally.

[0040] In the transport direction, the film transport web has, in particular, a web component extending from the flat material transport web perpendicularly, specifically upwards, after the flatbed press. This means that the transport webs for the flat material and the embossing foil, which run parallel to each other within the flatbed press, diverge at the exit of the flatbed press. The film transport web, in the transport direction, extends diagonally upwards after the flatbed press.

[0041] The peeling element is now arranged in such a way, relatively and in particular at a distance from the flat material transport track, that the embossing foil web adhering to the embossed flat material, which is transported away from the flatbed press and past the peeling element below it, is held back and peeled off by the peeling element.

[0042] According to a particular embodiment of the invention, the peeling element is arranged relatively and, in particular, at a distance from the flat material transport track or from the flat material, such that the embossing foil web adhering to the embossed flat material is peeled from the flat material, forming an open foil loop extending downstream from the peeling element in the transport direction of the flat material, hereinafter referred to as peeling loop.

[0043] In this case, the peeling element also serves to form an open peeling loop. The formation of this peeling loop creates an acute peeling angle, viewed in the transport direction of the flat material, between the embossing foil web peeled behind the peeling point and the embossing foil web adhering to the flat material in front of the peeling point. This angle has a positive effect on the peeling process.

[0044] The acute peel angle is, for example, less than 90° (degrees), in particular less than 75°, in particular less than 60°, and most especially less than 45°. The acute peel angle is also, for example, greater than 0°, in particular greater than 5°, in particular greater than 10°, and most especially greater than 15°.

[0045] According to a further development of the flatbed stamping press, the foil web guiding and transport device comprises a deflecting element, located at the exit of the flatbed press above the flat material transport web and in front of the peeling unit, for diverting the stamping foil web away from the transport direction of the flat material. The stamping foil web is guided between the deflecting element and the peeling unit.

[0046] The peeling element is positioned downstream of the deflecting element in the transport direction of the flat material.

[0047] The deflecting element is therefore arranged on the same side of the flat material as the peeling element. In particular, the deflecting element is arranged above the flat material.

[0048] The deflecting element forms a curved deflection surface for redirecting the embossing foil web from the transport direction of the flat material. The deflecting element can be a longitudinal component, such as a rod, running transversely to the transport direction of the embossing foil web. The deflection surface of the deflecting element is stationary, allowing the peeled-off embossing foil web to slide over the deflection surface.

[0049] The deflection device is arranged at a distance from the flat material transport track or from the flat material.

[0050] According to a further development of the invention, the peeling element is arranged at a distance from the flat material transport track or from the flat material.

[0051] The distance of the deflecting device to the flat material transport track or to the flat material is in particular greater than the distance of the peeling device to the flat material transport track or to the flat material.

[0052] The peeling element can be arranged, for example, at a distance of 1 mm or greater, in particular 2 mm or greater, and especially 3 mm or greater, from the flat material transport track or from the flat material.

[0053] The peeling element can also be arranged, for example, at a distance of 30 mm or less, in particular 20 mm or less and especially 10 mm or less from the flat material transport track or the flat material.

[0054] The peeling element forms a particularly curved deflection surface to deflect the embossing foil web from the transport direction of the flat material.

[0055] The peeling element can be a longitudinal component, such as a rod, running transversely to the transport direction of the embossing foil web. The deflection surface of the peeling element can be stationary, so that the peeled embossing foil web slides over the deflection surface.

[0056] The peeling element can also be a rotating roller. Accordingly, the roller's outer surface forms a rotatable deflection surface for the peeled embossing foil web. The roller can be actively driven or freely rotatable.

[0057] According to a further development of the invention, the flat embossing printing machine or the foil feeding device includes an unwinding device for unwinding the embossing foil web from a spool.

[0058] According to a further development of the invention, the flatbed stamping machine or the foil feeding device includes a foil storage unit arranged in front of the flatbed press, in particular between the unwinding device and the flatbed press, for temporarily storing a foil web length of the stamping foil web between two stamping operations.

[0059] The foil storage unit includes, in particular, a storage formation device for filling a receiving space of the foil storage unit with embossing foil web lengths.

[0060] The film storage unit is specifically designed to temporarily store excess film web length that is advanced or advanced beyond the predefined preferred length by the flatbed press and then retracted against the preferred direction by the film feeder. This is achieved without the need to rewind the excess film web length onto the unwinding reel.

[0061] Furthermore, the film storage unit is specifically designed to temporarily store a film web length for a subsequent film feed.

[0062] Flatbed stamping presses have very short press cycles and therefore high cycle rates, which can include, for example, 50 stamping passes per minute. This necessitates high foil feed speeds. Accordingly, the required length of the stamping foil web must be provided quickly. Since unwinding the stamping foil web from a take-up reel is a relatively slow process, a foil buffer with a short response time for releasing a buffered length of stamping foil web is preferably provided between the take-up reel and the flatbed press. The intermediate foil buffer allows for a slower, and in particular continuous, unwinding of the stamping foil web from the take-up reel that is not directly coupled to the foil feed. The unwound stamping foil web is buffered until needed.

[0063] Accordingly, the preferred length of the embossing foil web for the foil feed is taken from the foil storage.

[0064] The film storage unit is in particular a film loop storage unit in which a film web length in the form of at least one open film loop is temporarily stored in a loop receptacle.

[0065] The storage device is, in particular, a differential pressure device for drawing a length of stamping foil web into the foil storage unit, especially for forming an open foil loop, by means of an air pressure difference exerted on the foil web. The air pressure difference can be generated, for example, by applying an airflow to the stamping foil web, e.g., by means of a compressed air device. The air pressure difference can also be generated by applying a vacuum to the foil web, e.g., by means of a vacuum device. A combination of the two aforementioned methods is also possible.

[0066] If the air pressure difference is generated by applying a vacuum, the loop holder can be a suction channel in which a suction draft is applied, drawing in the embossing foil web that has passed the channel opening. Such a foil loop storage device is described, for example, in EP 0 858 888 A2.

[0067] The invention further relates to a method for operating the flat embossing printing machine described above according to the invention and for

[0068] Peeling off the embossing foil web from an embossed flat material following the embossing process.

[0069] To perform an embossing process, the foil web and the flat material are transported and positioned in the open flatbed press via the embossing table using a foil feeder. The foil web and the flat material are then brought together by closing the flatbed press, whereby the die plate with the heated embossing dies is pressed against the embossing table and the embossing process is carried out by means of pressure and heat, in which image elements are transferred from the foil web to the flat material.

[0070] After the embossing process is complete, the flatbed press is opened and the embossed flat material, along with the pronounced section of embossing foil, is transported away from the press. Simultaneously, a pre-set length of the foil is advanced by a foil feeder. The section of embossing foil transported away from the flat material is then detached from the flat material at the press exit and transported separately.

[0071] The preferred length of the foil pre-roll corresponds to the embossing section in the flatbed press, including any blank section on which, for example, image marks for accurate registration of the embossing foil web in the flatbed press may be placed. A typical pre-roll length might be, for example, 700 mm.

[0072] The control unit is generally designed so that the foil feed unit performs a foil feed with a defined feed length in each embossing cycle. The foil feed is executed according to a predefined speed profile stored in the control unit. The foil feed unit provides the required feed length, for example, in a foil buffer.

[0073] The predefined foil feed ensures, on the one hand, that a sufficient section of foil web containing the image elements is fed into the flatbed press. On the other hand, to avoid unnecessary foil consumption, it also ensures that no excess or excessive length of foil web is fed, the image elements of which cannot be embossed.

[0074] The separation of the pronounced embossing foil web section from the flat material exiting the flatbed press is achieved by guiding the embossing foil web into a deflection.

[0075] The inventive method is characterized in that, following the embossing process, the flat material is transported away from the open flatbed press and past the peeling element along the flat material transport path, whereby the embossing foil web encounters the peeling element and triggers the peeling of the embossing foil web from the flat material.

[0076] The flat material is transported past the peeling organ, especially below it.

[0077] The peeling mechanism serves primarily to retain the embossing foil web adhering to the flat material. In other words, the peeling mechanism prevents the embossing foil web adhering to the flat material from being transported further in the direction of travel.

[0078] According to a further development of the process, the embossing foil web adhering to the flat material is peeled off the flat material, forming an open peeling loop that extends or forms downstream from the peeling element in the transport direction of the flat material.

[0079] One leg of the peeling loop is formed by a section of embossed foil web adhering to the flat material.

[0080] The peeling loop can reach a loop length of up to 50 mm, and in particular up to 100 mm.

[0081] The formation of the peeling loop or the loop length of the peeling loop is controlled in particular by the speed profile of the film feed.

[0082] Thus, after the embossing process is complete and the flatbed press is opened, the film feed begins with a significant delay compared to the transport of the flat material from the press. This means that the film feed only starts after the embossed flat material has already been pulled out of the press to a certain extent.

[0083] This allows the embossed flat material, along with the adhering embossing foil web, to be advanced towards or beyond the peeling element without the advancing, free embossing foil being immediately pulled along by the foil advance mechanism. The latter would prevent or hinder the formation of a peeling loop.

[0084] The greater the delay in film feed, the larger the peeling loop will be.

[0085] During the peeling process, the loop length can be influenced or controlled by the speed profile of the film feeder. An increase in the film feeder speed relative to the sheet transport results in a smaller peeling loop. A decrease in the film feeder speed relative to the sheet transport results in a larger peeling loop.

[0086] Since the speed profile of the sheet transport is generally unchangeable, the relative increase or decrease in speed occurs primarily through a change in the film feed speed.

[0087] According to a particular embodiment of the process, the film feed and the sheet transport have the same speed during the peeling process. Accordingly, the loop size or length remains constant during the peeling process.

[0088] Towards the end of the peeling process, however, the foil feed speed relative to the sheet transport can be increased to reduce or even eliminate the peeling loop. Reducing or even eliminating the peeling loop towards the end of the peeling process also reduces the excess foil web length.

[0089] For process-related reasons, it is desirable that the retracted excess foil web length be as short as possible. This is to minimize the amount of excess foil that fills the foil reservoir. Furthermore, the embossing cycle should not be prolonged by extensive retraction of excess foil web length. Additionally, the less excess foil that needs to be retracted, the faster and more precise the registration-accurate positioning of the embossing image foil by reading image marks.

[0090] Therefore, in a further development of the process, it is provided that towards the end of the peeling process the speed of the film feed is increased relative to the speed of the flat material transport, such that the peeling loop is regenerated and, in particular, is resolved at the end of the peeling process.

[0091] Furthermore, the loop length or shape can vary during the peeling process due to a changing peeling force at the peeling point or peeling line.

[0092] This means that the peeling process of the stamping foil web from the flat material is not necessarily uniform. The peeling force can vary within a single peeling process. This occurs, for example, if the carrier film is not continuously printed with image elements in the transport direction. In other words, the stamping foil web does not adhere to the flat material, or adheres only weakly, in the areas between two consecutive image elements or embossing images. Due to the lack of or reduced peeling force between the image elements or embossing images, the peeling point springs back against the transport direction in these areas, leading to a drop in tension in the already peeled stamping foil web after the peeling point. This drop in tension, in turn, can lead to an increased peeling angle, a reduction in loop length, and deformation and therefore a change in the shape of the peeling loop due to the abrupt decrease in film tension.

[0093] If the foil web is continuously printed with image elements or embossing images in the transport direction, a uniform peeling force can be assumed. The loop tension remains constant accordingly. The loop length during the peeling process is only influenced by the aforementioned speed difference between the foil feed speed and the transport speed of the flat material.

[0094] When processing foil stamping webs, whose carrier foil webs can be relatively easily separated from the flat material after stamping, the separation process usually takes place immediately after exiting the flatbed press, below the deflection element of the foil web guide and transport system. The foil stamping web is thus separated from the flat material by means of a shear separation.

[0095] In contrast, with embossing foil webs that exhibit poorer peelability, the flat material with the adhering embossing foil web moves downstream away from the flatbed press towards the peeling element and, forming an open peeling loop, continues downstream beyond the peeling element.

[0096] The downstream movement of the flat material with the attached image foil web now requires the embossing foil web to be guided in the preferred direction by the flatbed press, which goes beyond the preferred length of the predefined foil advance.

[0097] The trailing excess length of the embossing foil web corresponds approximately to the distance between the peeling point of the embossing foil web immediately before its detachment from the flat material at the trailing end of the embossed flat material or at the trailing edge of the embossed sheet and the exit-side end of the embossing area of ​​the flatbed press (any blind sections not included).

[0098] According to a further development of the process, an excess length of embossing foil web, which is advanced by the flatbed press, is now retracted after the peeling process in the opposite direction to the foil advancement. Retracting the excess foil web also restores a predefined foil tension in the flatbed press. In some cases, this also ensures that the embossing foil web is positioned in register with the flat material in the flatbed press for the subsequent embossing process.

[0099] Since the foil guiding and transport system does not allow any foil web length to be retracted from the foil feed unit, the foil web can simply be retracted until a defined foil tension is reached, as mentioned. Therefore, the excess foil web length does not need to be known for this process step.

[0100] The withdrawn excess foil web length is temporarily stored in the foil buffer, specifically for a later embossing process. This means the withdrawn excess foil web length becomes part of a buffered foil web length for later foil feeding.

[0101] To provide a sufficient length of stamping foil temporarily stored in the foil storage for a subsequent foil feed, in particular, further stamping foil web length is unwound from the unwind roll and temporarily stored together with the retracted excess stamping foil web length in the foil storage, especially in a foil loop.

[0102] The guiding of the embossing foil web through the flatbed press therefore takes place over several embossing cycles in a kind of pilgrimage-step procedure, in that the image foil web is advanced over the embossing table by the preferred length plus foil web excess length after the embossing process and then retracted by the foil web excess length and, following the subsequent embossing process, is again advanced over the embossing table by the preferred length plus foil web excess length, etc.

[0103] The excess foil web is retracted, in particular, by means of the foil storage unit's storage element. During the peeling process, this storage element exerts a tensile force on the foil web against the direction of travel. This tensile force maintains the foil tension while simultaneously enabling foil advancement and the retraction of the excess web length. Consequently, the tensile force exerted against the direction of travel is less than the tensile force exerted on the foil web during foil advancement. This also applies specifically to the tensile force exerted to retract the excess foil web length.

[0104] According to a further development of the process, the excess length of the stamping foil web that is not pulled forward by the foil feed unit springs back due to the tensile force as soon as the stamping foil web is completely detached from the flat material. This occurs when the peel point reaches the trailing end of the stamped flat material or the trailing edge of the sheet and detaches from the flat material. The retraction of the stamping foil web can occur, in particular, in a whip-like motion.

[0105] If the image elements of the stamping foil webs are to be applied to the flat material with precise positioning or registration, image marks can be applied to the stamping foil web and detected by image mark sensors. Based on the image marks detected by the image mark sensors, the foil feed can be executed by the control unit with precise positioning or registration to the flat material.

[0106] For registration of the foil stamping web, a constant foil tension is required. Therefore, registration of the foil stamping web takes place primarily in a section of the web where the foil tension can be monitored and controlled.

[0107] A brake and guide wall can be arranged between the foil storage unit and the flatbed press. The embossing foil web is guided past this wall, and it serves as a foil tensioning device for tensioning the embossing foil web in the open flatbed press. Such a brake and guide wall is described, for example, in the embodiment shown below. Figure 1 A more detailed description of a brake and guide wall can also be found in publication EP 1 593 503 A2.

[0108] Additionally or alternatively, a brake and guide wall can be arranged between the peeling element or deflection rod and the film feed unit, enabling control of the film tension between the brake and guide wall and the film feed unit. The construction of the brake and guide wall can be as described above.

[0109] For registering the stamping foil web, a logo sensor is arranged along the foil transport web to detect and read logos on the foil web. The logo sensor is located, in particular, in a section of the stamping foil web where the foil tension can be monitored and controlled. This is especially the case following a braking and guiding wall. Possible positions for logo sensors are shown, for example, in connection with the embodiment shown in [reference to relevant figure]. Figure 1 revealed.

[0110] The inventive device and the associated method allow for the safe, trouble-free, and damage-free removal of the embossing foil web from the flat material, even with release layers exhibiting high adhesion. The formation of a peeling loop changes the principal directional component of the peeling force acting on the flat material from perpendicular to parallel. This reduces the stress on the flat material, even under high peeling forces, preventing deformation or other damage.

[0111] Furthermore, the peeling mechanism also helps to ensure that the flat material is not deflected perpendicular to the transport path in the direction of the immediately peeled embossing foil web during the peeling process.

[0112] Another aspect concerns controlling the foil tension of the foil section fed through the flatbed press. To prevent wrinkling and thus embossing errors, it is necessary to pre-tension the foil section before the embossing process. Applying a predetermined or defined foil tension for each embossing operation also enables controlled and accurate transfer of the embossed images onto the flat material. The embossing foil has a certain degree of stretchability or elasticity, meaning that applying foil tension leads to stretching of the foil and thus also to a shift in the embossed images relative to each other.

[0113] For accurate transfer of the embossing images onto the flat material, the film elongation must be taken into account during pre-tensioning or tensioning of the embossing foil web section. This means that the embossing images are arranged on the embossing foil in such a way that they are transferred to the flat material in register at a defined film tension or elongation. The film elongation depends not only on the tensile stress applied to the embossing foil web, but also on the elasticity and temperature sensitivity of the embossing foil used and its backing film. These factors must be considered when determining the film elongation.

[0114] Accordingly, the foil tension of a foil web section must be adjusted when setting up the flatbed stamping press so that the stamping images of the foil web section fed through the press are in register with the underlying flat material. It is important that, after setting up the flatbed stamping press, the same foil tension is applied for all stamping cycles of a production run. Only in this way will the stamping images be transferred to the flat material with perfect registration in every stamping cycle.

[0115] If different stamping foils with different properties are used for a subsequent production batch, the foil tension must be readjusted when setting up the flat stamping machine.

[0116] As mentioned above, a brake and guide wall with a guide surface for the stamping foil web can be arranged upstream of the flatbed press as part of a foil tensioning device, viewed in the transport direction of the stamping foil web. The stamping foil web is guided past this guide wall, which serves to tension the foil web in the open flatbed press. The guide surface interacts with a vacuum device, which generates a vacuum on the guide surface. The applied vacuum causes the stamping foil web to press against the guide surface of the brake and guide wall. The applied vacuum also causes the stamping foil web to slow down. The greater the applied vacuum, the stronger the braking effect on the stamping foil web and the higher the foil tension of the stamping foil web section as it passes through the flatbed press, and vice versa.

[0117] As described in detail above, after the stamping foil web has completely detached from the stamped flat material following a stamping process, it springs back against its transport direction. To restore foil tension, the stamping foil web must therefore be retracted by a defined distance against its transport direction. This is achieved, for example, by a foil reservoir positioned upstream of the stamping foil web in the transport direction, as described above. However, retracting the stamping foil web, e.g., into the foil reservoir, is only possible if the brake and guide wall does not exert any braking effect and consequently no negative pressure or suction on the stamping foil web. Therefore, the brake and guide wall must be ventilated to allow the stamping foil web to retract.Accordingly, the brake and guide wall is alternately supplied with vacuum and ventilated over several embossing cycles. Since the switch between vacuum supply and ventilation cannot occur arbitrarily quickly for technical reasons, the brake and guide wall limits the shortening of the embossing cycles.

[0118] It is therefore a task of the present, further, unclaimed aspect to propose, as an alternative or supplement to a brake and guide wall, a film tensioning device for controlling the tension of the embossing film web section guided by the flatbed press, which allows a further shortening of the embossing cycles.

[0119] According to this aspect, the flat embossing machine for embossing a flat material contains: a flatbed press comprising a tool plate and an embossing table, a foil web guiding and transport device for guiding at least one embossing foil web along a foil transport web over the embossing table of the flatbed press, a flat material guide for guiding a flat material along a flat material transport web through the flatbed press, a foil tensioning device for tensioning a section of embossing foil web guided through the flatbed press, and a control device for operating the flatbed embossing machine.

[0120] The film tensioning device now includes, according to the second aspect: a film clamping device for clamping the stamping foil web at a clamping point upstream of the flatbed press in the transport direction of the stamping foil web, a film deflection device for deflecting the at least one stamping foil web from the film transport web in the transport direction of the stamping foil web viewed after the clamping point for the purpose of controlling the film tension.

[0121] The foil tensioning device is specifically designed to temporarily deflect the embossing foil web during an embossing cycle or process in order to control the foil tension.

[0122] The foil deflection device is specifically designed to deflect at least one embossing foil web from the foil transport web between the clamping point and the flatbed press.

[0123] According to further training, the aforementioned film clamping device is a first film clamping device, and the clamping point is a first clamping point. The film tensioning device further includes a second film clamping device for clamping the at least one embossing foil web at a second clamping point located downstream of the flatbed press in the transport direction of the at least one embossing foil web. The film deflection device is designed to deflect the at least one embossing foil web from the film transport web between the first and second clamping points.

[0124] The film tensioning device is specifically part of, or associated with, the film web guiding and transport system. The (first) film clamping device and the film deflection device are specifically part of, or associated with, the film feeding system.

[0125] The second film clamping device, if present, is in particular part of the film guidance device or associated with it.

[0126] The (first) clamping point and the film deflection device are located, in particular, at the press inlet. The (first) clamping point and the film deflection device are located, in particular, directly in front of the flatbed press.

[0127] The second clamping point, if present, is located particularly at the press outlet or – if present – ​​downstream of the peeling element. The second clamping point is located particularly directly after the flatbed press or – if present – ​​directly after the peeling element.

[0128] By arranging the clamping point(s) in the immediate vicinity of the press inlet or outlet, the section of embossing foil to be clamped is kept as small as possible, which allows for more precise positioning of the embossing foil or its embossing images in the flatbed press.

[0129] The term "clamping" means, in particular, that the embossing foil is held by the clamping device, i.e., it cannot be moved or pulled through the clamping point. The clamping can be area-wide or line-like. The embossing foil web is clamped by the foil clamping device, especially across its entire width.

[0130] The foil clamping device is specifically designed to assume a clamping position in which the stamping foil web is clamped, and a transport position in which the stamping foil web can be moved by the foil clamping device.

[0131] The claimed foil clamping device is characterized in particular by the fact that it has a clamping element on both sides of the embossing foil web, between which the embossing foil web can be clamped.

[0132] At least one clamping element of the foil clamping device is designed to assume a clamping position in which the stamping foil web is clamped, and a transport position in which the stamping foil web can move past the foil clamping device in the transport direction. The clamping element is, in particular, movably mounted for this purpose.

[0133] Thus, at least one clamping element can be, for example, a clamping roller, which is blocked in the clamping position, i.e., does not rotate, and is rotatable, in particular freely rotatable, in the transport position.

[0134] According to a further development of at least one clamping element, this element is movable towards the foil web with a movement component transverse to the foil transport path, and in particular pivotable, to clamp the foil web, i.e., to assume a clamping position. To release the clamping, i.e., to assume the transport position, the clamping element is movable away from the foil web with a movement component transverse to the foil transport path, and in particular pivotable. The away movement is, in particular, the opposite movement to the towards movement. The movable clamping element can also be, for example, a clamping roller.

[0135] The movable or movably mounted clamping element is driven or moved, in particular, by a drive such as an electric motor or a pneumatic or hydraulic drive. The drive is controlled by the control unit.

[0136] A clamping element can also be stationary, i.e., not displaceable and, in particular, not movable. Such a clamping element can, for example, be formed by the brake and guide wall. However, it is also conceivable that no brake and guide wall is provided, since the essential function of the brake and guide wall, namely the tensioning of the embossing foil web, is performed by the foil tensioning device.

[0137] A clamping element can also be formed by a stationary, i.e., non-displaceable and in particular non-movable, guide element, such as a guide roller or guide rod.

[0138] However, it is also conceivable that both clamping elements are mounted in a movable, i.e., displaceable, manner.

[0139] In the context of the present aspect, "perpendicular to the film transport web" means in particular parallel to the surface normal of the embossing film web.

[0140] According to a further development of the film tensioning device, the film deflection device for deflecting the embossing film web in the transport direction of the embossing film web is arranged in front of the flatbed press.

[0141] The foil deflection device is arranged, in particular, between a foil storage unit, such as a foil loop storage unit, and the flatbed press. The foil storage unit serves, in particular, for the temporary intermediate storage of a foil web length of the stamping foil web between two stamping operations.

[0142] The foil deflection device includes, in particular, a foil deflection element which, for the purpose of deflecting the embossing foil web, is movable, in particular pivotable, with a movement component transverse to the foil transport web. The foil deflection element can thus be pivotally mounted via a pivot axis. The foil deflection element can, for example, be part of a lever mechanism. The foil deflection element can also be movable via a linear movement with a movement component transverse to the foil transport web. The foil deflection element is driven or moved, in particular, by a drive such as an electric motor or a pneumatic or hydraulic drive. The drive is controlled by the control unit.

[0143] To deflect the foil web, the foil deflection element is moved towards the foil web with a movement component transverse to the foil transport path. The foil deflection element pushes the foil web laterally, i.e., transversely to the foil transport path. The laterally deflected foil web forms, in particular, a laterally protruding bulge or open foil loop. This deflection of the foil web lengthens the foil path or transport distance of the foil web, especially between the counter-support elements described below.

[0144] Since the foil web is clamped both before and after the foil deflection unit when viewed in the transport direction, the additional travel distance for lateral deflection can only be provided by tensioning or stretching the foil web section guided through the flatbed press. The tension or stretch of this foil web section can be adjusted relatively easily by changing the degree of deflection. For example, a foil stretch of 4 mm to 10 mm per linear meter is conceivable.

[0145] According to a further development of the film tensioning device, the film deflection device comprises two counter-support elements arranged at a distance from each other along the transport direction of the embossing film web, which are located on the side of the embossing film web opposite the film deflection element. A deflection section of the embossing film web is formed between the counter-support elements.

[0146] The counter-supports ensure that the embossing foil web is deflected only between them. The foil deflection element acts accordingly between the two counter-supports, deflecting the embossing foil web, or is moved between the two counter-supports towards the embossing foil web. When the embossing foil web is deflected, it is redirected around the counter-supports into the deflection.

[0147] The counter-supporting elements can be guide elements, such as guide rods or guide rollers. The counter-supporting elements are typically arranged in a stationary position.

[0148] If, in the direction of film transport, several foil webs are guided side by side, especially parallel to each other, through the flatbed press, then each foil web is assigned its own foil deflection device. This allows for the individual adjustment or control of the foil tension for each foil web.

[0149] In a further development of this variant, it is also conceivable that each foil roll is assigned its own foil clamping device, or a first and second foil clamping device. This allows for individual clamping of the foil rolls. However, the foil rolls can also be clamped by a common foil clamping device, or by a first and second foil clamping device.

[0150] Another aspect is the corresponding procedure for operating a flatbed stamping press described above. For this, the stamping foil web and the flat material are positioned in the flatbed press and brought together by closing the press. Stamping then transfers the embossed images from the foil web to the flat material.

[0151] The further, unclaimed aspect is characterized by the fact that the stamping foil web is clamped at the clamping point, or at the first and second clamping points, before the flatbed press is closed, and then the foil deflection device is moved towards the stamping foil web, in particular pivoted, and the foil deflection device deflects the stamping foil web transversely to the foil transport web until the stamping foil web section guided through the flatbed press has a predetermined tension.

[0152] As mentioned, the film tensioning device allows for the control or adjustment of the film tension and thus controlled film stretching before each embossing cycle.

[0153] Furthermore, the foil tensioning device is characterized by its ability to allow a comparatively quick change between clamping and transport positions. This is particularly important in a flat foil stamping press with a peeling unit according to the first aspect of the invention. During a stamping cycle, the clamping device must be in the clamping position to ensure accurate registration of the foil web. Following the stamping process, it must then switch to the transport position to retract any excess foil and subsequently advance the foil web. This means that the clamping device continuously switches between the clamping and transport positions over several stamping cycles. The faster this changeover between the clamping and transport positions, the shorter the stamping cycle.With the film tensioning device, faster changes between clamping and transport positions are now achieved compared to a brake and guide wall, and thus shorter cycle times are achieved.

[0154] The invention will now be explained in more detail with reference to an exemplary embodiment, which is illustrated in the accompanying figures. The figures schematically show: Fig. 1: a cross-sectional view of a flat embossing printing machine according to the invention; Fig. 2: a cross-sectional view from the area of ​​the peeling element of the flat embossing printing machine according to Figure 1 ; Fig. 3: a cross-sectional view of a typical stamping foil; Fig. 4: speed profile of foil feed and sheet transport; Fig. 5: a cross-sectional view of another embodiment of a flatbed stamping press.

[0155] In principle, identical parts in the figures are designated with the same reference numerals. For the sake of understanding the invention, certain features, for example, features not essential to the invention, are not shown in the figures. The described embodiment is exemplary of the subject matter of the invention or serves to illustrate it and has no limiting effect.

[0156] The Figure 1 Figure 1 shows an embodiment of a flatbed embossing machine 1 according to the invention, comprising a flatbed press 2 designed as a flat-flat press for embossing sheets 12. The flatbed press 2 includes an embossing table 3 with a counter-pressure plate and, as a counterpart, a tool plate 4 with heated embossing tools, also called clichés, arranged on the embossing side (not shown).

[0157] The sheets 12 to be embossed are individually pulled from a stack of sheets 63, which is provided in a feeder 60, and transported via a transport device 61 to the flat embossing table 3. For this purpose, the separated sheet 12 is gripped and held at its leading edge by a gripper bar 62 and pulled by this onto the embossing table 3 of the open flatbed press 2 and positioned below an embossing foil web 6.

[0158] The stamping foil web 6 has a multi-layered structure and comprises a carrier film 55, e.g. made of polyester, which serves as a carrier for the further layers (see Figure 3 On the carrier film 55, an embossed image 57 is arranged via a release layer 56. On the embossing side of the embossing foil web 6, an external, activatable adhesive layer 58 is arranged on the embossed image 57.

[0159] During the embossing process, the embossed image 57, with the adhesive layer 58 facing forward, is pressed onto the sheet 12. By activating the adhesive layer 58, e.g., by heat, the embossed image 57 bonds to the sheet 12 via the adhesive layer 58. Conversely, the release layer 56 loses or reduces its adhesive strength due to the application of heat, so that the carrier film 55 can subsequently be detached from the embossed image 57, which is applied to the sheet 12, along the release layer 56.

[0160] Following the embossing process, the embossed sheets 12 are each pulled from the open flatbed press 2 by the gripper beam 62 and fed to a boom 70, forming a stack 73 of embossed sheets 12.

[0161] The flatbed stamping machine 1 further includes a foil web guiding and transport device 7 for transporting and guiding a stamping foil web 6, also called image foil web, with stamping images 57 arranged on it through the flatbed press 2.

[0162] The film web guiding and transport device 7 includes a film feed device 20 for feeding a stamping film web 6 to the flatbed press 2. The film feed device 20 comprises an unwinding device 21 for receiving an unwind roll 22, on which the stamping film web 6 is wound as a roll, and from which stamping film web 6 is unwound for the film feed.

[0163] In the transport direction T 2 of the foil web 6 downstream after the unwinding device 21 and before the flatbed press 2, the foil stamping machine 1 or the foil web guiding and transport device 7 contains a foil loop storage unit 23. The foil loop storage unit 23 comprises at least one loop holder 25 for receiving a foil loop 11 and a vacuum device 24 for forming the foil loop 11 in the loop holder 25. For this purpose, a vacuum is exerted by the vacuum device 24 on the foil web 6 as it passes the loop holder 25. This draws the foil web 6 into the loop holder 25, forming the foil loop 11.

[0164] As discussed above, the foil feed on the flatbed press 2, which is coordinated with the embossing cycle, is intermittent. For example, the embossing foil web 2 remains stationary in the closed flatbed press 2 during the embossing process, while at the beginning of a new embossing cycle, the foil feed occurs at high speed when the press is open. The foil feed must be as gentle, precise, and fast as possible, so that the embossing foil web 6 is advanced quickly yet gently to the next embossing position, positioned precisely or even in register on the embossing table 3, and held in a fixed position when the flatbed press 2 is closed.

[0165] When switching between stationary and film advance, or between film advance and stationary, the driven speed profile shows high positive or negative accelerations, respectively.

[0166] Since the unwinding device 21 with the heavy unwinding roller 22 reacts far too sluggishly to the rapidly and, above all, strongly changing transport speed of the stamping foil web 6 on the flatbed press 2 between standstill and high feed speed, speed differences between the feed speed on the flatbed press 2 and the web speed or unwinding speed on the unwinding roller 22 are balanced or compensated by corresponding enlargement and reduction of the foil loop 11 in the foil loop storage 23.

[0167] Thus, when obtaining foil web lengths for foil feeding, in contrast to the unwinding device 21, only the weight of the foil web length, which is temporarily stored in loop form, needs to be moved from the loop holder 25. Furthermore, the foil web length stored in loops is not mechanically held in the foil storage unit. As a result, the foil loop storage unit 23 can provide foil web lengths for rapid and high-speed foil feeding with a very short response time.

[0168] The foil loop storage unit 23 is further assigned a sensor device 26 for detecting the stored embossing foil web length. The vacuum device 24 is controlled based on the storage data determined by the sensor device 26.

[0169] A flat brake and guide wall 27 can be arranged between the foil loop storage unit 23 and the flatbed press 2, against which the embossing foil web 6 is guided.

[0170] The brake and guide wall 27 serves as a film tensioning device and forms a guide surface over which the at least one embossing foil web 6 is guided. The guide surface interacts with a vacuum device by means of which a vacuum can be generated on the guide surface. The applied vacuum causes the embossing foil web 6 to press against or be drawn to the guide surface of the brake and guide wall 27. The applied vacuum also causes the embossing foil web 6 to slow down. The greater the applied vacuum, the stronger the braking effect on the embossing foil web 6, and vice versa. The guide surface can be formed by a cloth-like or textile-like, air-permeable support layer. This ensures gentle guidance of the sensitive embossing foil web 6 despite physical contact between the embossing foil web 6 and the guide surface.

[0171] The braking effect of the negative pressure applied to the guide surface and acting on the embossing foil web 6 passing by it allows the foil tension between the braking and guide wall 27 and a foil feed device 41 to be controlled. An increase in the negative pressure at the guide surface leads to a greater braking effect and thus to an increase in the foil tension.

[0172] As explained further below, controlled foil tension is particularly important in the area of ​​the flatbed press 2 and in connection with the capture of image marks, as this is the only way to ensure that the stamping foil web 6 is free of burrs and, if necessary, precisely positioned or registered in the flatbed press 2.

[0173] However, the brake and guide wall 27 is not a mandatory feature of this invention.

[0174] The foil web guiding and transport device 7 further comprises a foil path guiding device 40 for guiding the embossing foil web 6 away from the flatbed press 1.

[0175] The foil guide device 40 comprises a foil feed device 41 downstream of the flatbed press 2 for performing foil feed at the beginning of a new embossing cycle. The foil feed device 41 can, for example, comprise a driven feed roller or a driven feed roller pair, by means of which the embossing foil web 6 is fed forward.

[0176] The foil guide device 40 further comprises, downstream of the foil feed device 41, a winding roller 42 for winding the pronounced embossing foil web 6.

[0177] The embossing foil web 6 is guided through the flatbed press 2 by means of the foil web guide and transport device 7 above the embossing table or above the sheet 12 positioned on the embossing table 3 and below the tool plate 4.

[0178] At the exit of the flatbed press 2 in the transport direction T 2 of the embossing foil web 6, a deflecting rod 15 is arranged above the transport web 18 of the sheet 12 and the embossing foil web 6, which ensures a deflection of the embossing foil web 6 from a horizontal transport web 17 obliquely upwards.

[0179] The foil guide device 40 further comprises a peeling element 16, which is arranged downstream in the transport direction T 1 of the sheet 12 of the deflecting rod 15 and is also arranged above the transport track 18 of the sheet 12. The deflecting rod 15 and the peeling element 16 are arranged such that the transport track 17 of the embossing foil web 6 runs between the deflecting rod 15 and the peeling element 16.

[0180] Furthermore, the film guide device 40 between the deflecting rod 15 or the peeling element 16 and the film feed device 41 can include a (further) flat brake and guide wall 43 to ensure a constant film tension between the film feed device 41 and the further brake and guide wall 43.

[0181] The additional brake and guide wall 43 can be constructed in the same way as the brake and guide wall 27 between film storage unit 23 and flatbed press 2. The additional brake and guide wall 43 is also not a mandatory feature of this device.

[0182] A logo sensor 44, also called a logo reader, can be arranged between the foil feed unit 41 and the brake and guide wall 43. This sensor detects the position of logos on the stamping foil web 6 for the purpose of register-accurate positioning of the stamping foil web 6 in the flatbed press 2. The logo sensor 44 is arranged in a section of the foil transport web 17 between the brake and guide wall 43 and the foil feed unit 41, in which controlled foil tension prevails.

[0183] Alternatively, the image mark reader 28 can also be arranged between the brake and guide wall 27 and the flatbed press 2. Alternatively, the image mark reader 13 can also be arranged on the input side of the flatbed press 2. Alternatively, the image mark reader 14 can also be arranged on the output side of the flatbed press 2.

[0184] All three positions for image mark sensors 13, 14, 28 have in common that a brake and guide wall 27 is placed upstream between film storage 23 and flatbed press 2 for the purpose of controlling the film tension.

[0185] The four image mark sensors 23, 14, 28, 44 shown at alternative positions along the transport path 17 of the embossing foil web 6 are also not a necessary feature of the present invention.

[0186] At the beginning of an embossing cycle, as mentioned, the embossing foil web 6 is advanced by the foil advance device 41 by a defined advance length in the transport direction T 2 of the embossing foil web 6 (advance direction). During this process, the embossing foil web length formed in the previous embossing cycle is transported or pulled out of the open flatbed press 2 in the advance direction T 2, and an as yet unformed embossing foil web length from the foil advance is transported or pulled into the open flatbed press 2. Furthermore, a new sheet 12 is transported from the feeder 60 into the open flatbed press 2 by means of a gripper beam 62.

[0187] If the foil stamping web 6 is to be positioned in register with the sheet 12 in the flatbed press 2, a logo sensor 13, 14, 28 or 44 reads so-called logos on the foil stamping web 6. For this purpose, the foil stamping web 6 is transported towards the end of the foil feed at a reduced feed speed (see also Figure 4 ).

[0188] The image mark sensor 13, 14, 28 or 44 is arranged downstream of a brake and guide wall 27 or 43 in a foil embossing web section with controlled foil tension.

[0189] Once the embossing foil web 6 and sheet 12 are positioned (in register) in the flatbed press 2, it is closed and the embossing process is carried out by forcefully bringing together the tool plate 4 and embossing table 3 using pressure and heat.

[0190] After completion of the embossing process, the flatbed press 2 is opened again and the embossed sheet 12, together with the pronounced embossing foil web length, is transported out of the open flatbed press 2.

[0191] During the foil feed at the exit of the flatbed press 2, the embossing foil web 6 is detached from the sheet 12. For this purpose, both the embossed sheet 12 are pulled out of the open flatbed press 2 by means of the gripper bars 62, and the embossing foil web 6 is pulled out by means of the foil feed. The embossed sheet 12 is pulled out of the flatbed press 2 in a substantially horizontal direction. The embossing foil web 6 is pulled away diagonally upwards, with the deflecting rod 15, located at the exit and above the embossing foil web 6, ensuring the deflection from a substantially horizontal guide to an diagonal upwards.

[0192] With relatively easily removable embossing foil webs 6, the foil web 6 is detached from the sheet 12 by means of a shear separation by pulling it diagonally upwards while simultaneously pulling the sheet 12 horizontally. The foil web 6 is deflected accordingly at the deflecting rod 15.

[0193] If, however, the embossing foil web 6 is not easily removable, it adheres to the sheet 12 and is pulled along horizontally with it. Accordingly, the peeling point 10 or the peeling line shifts downstream. The pulled-along embossing foil web 6 now strikes the peeling element 16, which is located further downstream above and at a distance from the sheet 12. As a result, the embossing foil web 6 is pulled under the peeling element 16, forming a peeling loop 9, until the retaining force generated by the foil tension is greater than the peeling force required to remove the embossing foil web 6 from the sheet 12 (see figure). Figure 2 Accordingly, peeling point 10 is now located downstream of peeling organ 16.

[0194] The formation of a peeling loop 9 peels the embossing foil web 6 from the sheet 12 at an acute peeling angle α. The acute peeling angle α, or rather the peeling element 16, which ensures the formation of the peeling loop and consequently the acute peeling angle α, also prevents the sheet 2 from being lifted and thus deformed by the adhering and upwardly peeled embossing foil web 6.

[0195] However, the peeling point 10, located downstream of the peeling element 16, pulls in an excess of the embossing foil web 8. This excess 8 is a section of unembossed foil web 6 that is pulled through the flatbed press 2 beyond the defined pre-draw length and exited from the flatbed press 2. This excess 8 is not pulled in by the foil feed unit 41, as the foil feed unit 41 only performs a foil feed with a predefined pre-draw length.

[0196] This excess foil web length 8 is now, after completion of the peeling process, i.e., when the peeling point 10 detaches from the sheet 2, retracted through the open flatbed press 2 against the preferred direction T 2. This is done by the foil loop storage unit 23, whose vacuum device 24 exerts a permanent tensile stress on the foil web 6, which is advanced towards the flatbed press 2, during the peeling process.

[0197] As soon as the foil web 6 has completely detached from the sheet 2, it snaps back towards the foil loop storage unit 23 due to the abrupt drop in tension. The excess foil web length 8 is retracted towards the foil loop storage unit 23. A foil web length corresponding to the retracted excess 8 is then formed in the foil loop storage unit 23 and temporarily stored for the next embossing cycle.

[0198] If a brake and guide wall 27 is arranged between the film loop storage unit 23 and the flatbed press 2, it is temporarily deactivated during the retraction of the excess film web length, thus eliminating the braking effect. This can be achieved, for example, by briefly venting the brake and guide wall 27. This prevents the retraction of the excess film web length through the film loop storage unit 23 from being hindered or even prevented by the braking effect of the brake and guide wall 27.

[0199] A new embossing cycle can now begin. The excess embossing foil web length temporarily stored in the foil loop storage unit 23 is subsequently supplemented by further embossing foil web length from the unwind roll 22, so that the total length of the foil web temporarily stored in the foil loop storage unit 23 corresponds at least to the preferred length.

[0200] The individual units, such as the unwinding unit, foil loop storage, flatbed press, foil feed unit, and sheet transport unit, or the individual subprocesses of the flatbed stamping press, foil unwinding, storage and release of stamping foil web length in and from the foil loop storage, sheet feed and sheet removal, foil feed and stamping process, etc., are controlled by the machine control unit 80. For this purpose, the machine control unit 80 also processes sensor data from image mark readers 13, 14, 28, or 44 and storage sensors 26.

[0201] In principle, in the flatbed stamping press 1, several stamping foil webs 6 can be guided simultaneously, in particular parallel to each other, through the flatbed press 2 for stamping the sheets 12 in several zones. These are driven by a foil feed device 41, each unwound from unwinding rollers 22 and transported through the flatbed press 2 via a foil loop storage unit 23 located upstream of the flatbed press 2 and wound onto a take-up roller 42 in the foil guide device 40.

[0202] The Figure 4 Figure 50 shows a schematic representation of the velocity profiles of the sheet transport and the foil feeder relative to each other. These velocity profiles are for illustrative purposes only and do not represent the actual velocity profiles.

[0203] After opening the flatbed press 2 (reference number: 52), the sheet transport is started first with speed profile 50. The sheet 12 is pulled out of the flatbed press 2 by means of gripper beam 62. After a slight delay, the foil feed starts with speed profile 51. Due to the delayed start of the foil feed, the sheet 12, together with the embossing foil web 6 adhered to it, is pulled towards the peeling unit 16 and, forming a peeling loop 9, is pulled under the peeling unit over a specific distance.

[0204] During a phase with constant speed between foil feed and sheet transport, the stamping foil web 6 is peeled from the sheet 12, forming a constant peel loop 9. Once the stamping foil web 6 has completely detached from the sheet 12 (reference numeral 53), the speed of the foil feed is also reduced to a so-called search speed. In a subsequent search run with the reduced foil feed speed, the image mark sensor searches for image marks on the stamping foil web 6 to ensure accurate registration of the stamping foil web 6 over the flatbed press 2 in preparation for a subsequent stamping cycle.

[0205] If precise registration of the foil web 6 is not required, the search function can be omitted. The foil feed speed is then reduced directly to zero towards the end of the foil feed.

[0206] The speed of the sheet transport is only reduced towards the end of the sheet transport with a certain delay compared to the speed profile 51 of the film feeder, and is lowered to zero. This is because the speed profile of the sheet transport is based on the so-called sheet repeat between two gripper beams 62. The distance traveled by one sheet repeat is significantly greater than the sheet length in the sheet transport direction T1.

[0207] After foil feed and sheet transport are completed, the flatbed press 2 is closed again for a new embossing cycle (reference 54).

[0208] It may be provided that the speed profile 51 of the foil feed temporarily shows an increase in speed (not shown) shortly before the end of the peeling process in order to regenerate the peeling loop 9 before the speed returns to zero towards the end of the foil feed or returns to the level of the search speed.

[0209] At the in Figure 5 The section shown from the area of ​​the flatbed press 2 is part of a flatbed embossing printing machine 1. It could, for example, be a flatbed embossing printing machine 1 as shown in the Figure 1 The machine shown is additionally equipped with a film tensioning device 90 according to the second aspect. However, the film tensioning device 90 is not limited to a flat embossing printing machine with a peeling element according to the first aspect of the invention, but is also suitable for other embodiments of flat embossing printing machines.

[0210] The flat embossing printing machine according to Figure 5 includes a foil tensioning device 90 for tensioning the embossing foil web section 89 guided through the flatbed press 2.

[0211] The film tensioning device 90 includes a first film clamping device 93 for clamping the stamping foil web at a first clamping point 94 located upstream of the flatbed press 2 in the transport direction T2 of the stamping foil web. The first film clamping device 93 includes a first and second clamping element 95, 27, between which the stamping foil web 6 is guided and clamped. For this purpose, the first clamping element 95, e.g., a clamping roller, is movable, in particular pivotable, towards the second clamping element 27, forming a clamping action. In the present embodiment, the second clamping element 27 is formed by a brake and guide wall 27.

[0212] Furthermore, the film tensioning device 90 includes a second film clamping device 96 for clamping the stamping foil web 6 at a second clamping point 98 downstream of the flatbed press 2 in the transport direction T2 of the stamping foil web 6. The second film clamping device 96 comprises a first and second clamping element 97, 43, between which the stamping foil web 6 is guided and clamped. For this purpose, the first clamping element 97, e.g., a clamping roller, is movable, in particular pivotable, towards the second clamping element 43, forming a clamping action. In the present embodiment, the second clamping element 43 is formed by a film brake 43.

[0213] Furthermore, the film tensioning device 90 includes a film deflection device 91 for deflecting the stamping foil web 6 between the first and second clamping points 94, 98 from the film transport web 17 in order to control the film tension and for controlled film stretching. The film deflection device 91 is arranged in front of the flatbed press 2 when viewed in the transport direction T2 of the stamping foil web 6.

[0214] The film deflection device 91 comprises a film deflection element 92, which is pivotable transversely to the film transport web 17 towards the embossing film web 6. The film deflection element 92 is pivotally mounted for this purpose via a pivot axis.

[0215] Furthermore, the foil deflection device 90 includes two counter-support elements 99 in the form of counter-support rollers arranged at intervals along the transport direction T2 of the stamping foil web 6. These are arranged on the side of the stamping foil web 6 opposite the foil deflection element 92. A deflection section of the stamping foil web 6 is formed between the counter-support rollers 99.

[0216] The counter-rollers 99 ensure that the stamping foil web 6 is deflected only between the counter-rollers 99. The foil deflection element 92 can be pivoted between the two counter-rollers 99 towards the stamping foil web 6.

[0217] To deflect the stamping foil web 6, the foil deflection element 92 is pivoted transversely to the foil transport web 17 towards the stamping foil web 6. The foil deflection element 92 pushes the stamping foil web 6 laterally away from the foil transport web 17 and deflects it laterally. The stamping foil web 6 is thereby deflected by the counter-rollers 99 or deflected out of the foil transport web 17. The laterally deflected stamping foil web 6 forms a laterally projecting foil loop.

[0218] The deflection of the stamping foil web 6 increases its travel distance. Since the stamping foil web 6 is clamped both before and after the foil deflection device 91 when viewed in the transport direction T 2, the additional travel distance for the lateral deflection of the stamping foil web 6 can only be provided by tensioning or stretching the stamping foil web section 89 guided by the flatbed press 2. The tension, and thus the stretching of the stamping foil web section 89, is then controlled by the degree of deflection of the stamping foil web 6.

Claims

1. A flat embossed printing machine (1) for embossing a flat material (12), comprising: - a flatbed press (2), comprising a tool plate (4) and an embossing table (3), - a foil web guidance and transport device (7) for guiding at least one embossing foil web (6) over the embossing table (3) of the flatbed press (2) along a foil transport path (17), - a flat material guidance (13) for guiding a flat material (12) through the flatbed press (2) along a flat material transport path (18), as well as - a control device (80) for operating the flat embossed printing machine (1), characterised in that the foil web guidance and transport device (7) subsequently to the flatbed press (2) as viewed in the transport direction (T1) of the flat material (12) comprises a peel-away element (16) which is arranged above the flat material transport path (18) as well as behind the foil transport path (17), for holding back and peeling the embossing foil web (6) away from the flat material (12) on transporting the flat material (12) away out of the flatbed press (2).

2. A flat embossed printing machine (1) according to claim 1, characterised in that the peel-away element (16) is arranged relative to the flat material transport path (18) in a manner such that the embossing foil web (6) which adheres to the embossed flat material (12) which is transported away out of the flatbed press (2) is held back by the peel-away element (16) and thus peeled away, amid the formation of an open peel-away loop (9) which coming from the peel-away element (16) extends downstream in the transport direction (T1) of the flat material (12).

3. A flat embossed printing machine (1) according to one of claim 1 or 2, characterised in that the foil web guidance and transport device (7) comprises a deflecting element (15) which, as viewed in the transport direction (T1) of the flat material (12), is arranged at the exit of the flatbed press (2) as well as above the flat material transport path (18) and in front of the peel-away element (16), for deflecting the embossing foil web (6) out of the transport direction (T1) of the flat material (12) wherein the embossing foil web (6) is led into a deflection between the deflecting element (15) and the peel-away element (16).

4. A flat embossed printing machine (1) according to one of the claims 1 to 3, characterised in that the peel-away element (16) is arranged at a distance of 1 mm or larger, in particular 2 mm or larger and very particularly of 3 mm or larger, to the flat material transport path (18).

5. A flat embossed printing machine (1) according to one of the claims 1 to 4, characterised in that the peel-away element (16) is arranged at a distance of 30 mm or less, in particular of 20 mm or less and very particularly of 10 mm or less to the flat material transport path (18).

6. A flat embossed printing machine (1) according to one of the claims 1 to 5, characterised in that the peel-away element (16) forms a deflecting surface for the deflection of the embossing foil web (6).

7. A flat embossed printing machine (1) according to one of the claims 1 to 6, characterised in that the flat embossed printing machine (1) comprises an unwinding device (21) for unwinding the embossing foil web (6) from an unwind roll (22).

8. A flat embossed printing machine (1) according to claim 7, characterised in that the flat embossed printing machine (1) comprises a foil store (23) which in the transport direction (T2) of the embossing foil web (6) is arranged in front of the flatbed press (2), in particular between the unwinding device (21) and the flatbed press (2), for the temporary intermediate storing of a foil web length of the embossing foil web (6) between two embossing procedures.

9. A flat embossed printing machine (1) according to claim 8, characterised in that the foil store (23) in particular comprises a store formation device (24) for filling the foil store (23) with an embossing foil web length.

10. A flat embossed printing machine (1) according to one of the claims 1 to 9, comprising a foil tensioning device (90) for tensioning an embossing foil web section (89) which is led through the flatbed press (2), wherein the foil tensioning device (90) comprises: - a foil clamping device (93) for clamping the at least one embossing foil web (6) at a clamping location (94) which considered in the transport direction (T2) of the at least one embossing foil web (6) is arranged in front of the flatbed press (2), and - a foil deflecting device (91) for deflecting the at least one embossing foil web (6) out of the foil transport path (17) after the clamping location (94) considered in the transport direction (T2) of the embossing foil web (6), for the purpose of controlling the foil tension.

11. A flat embossed printing machine (1) according to claim 10, characterised in that the foil deflecting device (91) is designed for deflecting the at least one embossing foil web (6) out of the foil transport path (17) between the clamping location (94) and the flatbed press (2).

12. A method for operating the flat embossed printing machine (1) according to one of the claims 1 to 11, wherein the embossing foil web (6) and the flat material (12) are positioned and brought together in the flatbed press (2) and embossing pictures (57) are transferred from the embossing foil web (6) onto the flat material (12) by way of an embossing procedure, characterised in that subsequently to the embossing procedure, the flat material (12) is transported away out of the opened flatbed press (2) along the flat material transport path (18) in the transport direction (T1) and past the peel-away element (16), wherein the embossing foil web (6) which is carried along and adheres to the flat material (12) meets the peel-away element (16) and activates a peeling of the embossing foil web (16) away from the flat material (12).

13. A method according to claim 12, characterised in that the embossing foil web (6) which adheres to the flat material (12) forms an open peel-away loop (9) which is coming from the peel-away element (16) and extends downstream as viewed in the transport direction (T1) of the flat material (12) while peeling away from the flat material (12).

14. A method according to claim 12 or 13, characterised in that an embossing foil web excess length (8) which is advanced through the flatbed press (2), in particular by formation of an open peel-away loop (9) is pulled back again counter to the transport direction (T2) of the embossing foil web (6) subsequently to the peeling-away procedure and in particular is intermediately stored in the foil store (23) for a later embossing procedure.

15. A method according to claim 14, characterised in that the embossing foil web excess length (8) is pulled back by way of the store formation device (24) of the foil store (23).