Clamping device and assembly for clamping template to holding cylinder of rotary die-cutting machine

Abstract

The invention relates to a clamping device (1) for clamping a die plate to a die holding cylinder of a rotary die-cutting machine, comprising a fluid pressure cylinder (11) with an axially displaceable piston (12). A clamping bolt (13) is attached to the piston (12), the clamping bolt (13) comprising a shank (13B) and a head (13A) extending radially from the shank (13B). The fluid pressure cylinder (11) is configured to displace the piston (12) axially outward in response to fluid injection into the fluid pressure cylinder (11). The clamping device further comprises a clamping spring (14) arranged to bias the piston axially inward. The clamping bolt (13) comprises a threaded portion (13C) through which the clamping bolt is attached to the piston (12) by means of a threaded connection. The head (13A) of the clamping bolt (13) may be configured to facilitate application of torque to the clamping bolt to release the clamping bolt from the piston by unscrewing.

Description

Technical Field

[0001] The invention relates to the technical field of rotary die cutting machines. Background Art

[0002] Rotary die cutters known in the art generally comprise a rotatingly arranged cylinder on which is mounted an element (usually a wooden element), called a die or template, which is provided with a blade. In use, the die-holding cylinder is generally rotated to bring the blade into contact with a cardboard blank fed between the die-holding cylinder and another cylinder in order to cut and shape the cardboard in a predetermined manner, for example according to the type of box to be produced.

[0003] It is known in the art to attach the template to the mold-holding cylinder by means of screws. Although this provides a stable and reliable attachment between the template and the cylinder, it also involves important disadvantages: the replacement of the mold usually involves a lot of work and takes a lot of time. Therefore, there is a need for alternative means for attaching the template to the mold-holding cylinder, preferably allowing easy and fast attachment and removal to facilitate the replacement of the mold. Moreover, the attachment must be reliable and stable, and the attachment means should be compatible with the basic durability of all the parts involved (including the template, which, as mentioned above, can be made of wood or other relatively sensitive materials).

[0004] US-5638733-A discloses what appears to be a complex mechanical system for attaching a die plate to a die holder. The system comprises a plurality of longitudinal rods attached to the die and extending in the axial direction of the machine, the rods having a C-shaped cross section. The die holder is provided with openings to receive the rods and with spring-loaded displaceable locking teeth which are operated by means of longitudinal control rods slidably arranged in longitudinal recesses in the die holder. The operation of the system involves a combination of movement of the rods in the axial direction and movement of the locking teeth in the circumferential direction.

[0005] US-5003854-A likewise discloses a mechanical template attachment system involving axial displacement of a locking member, namely, a longitudinally extending locking rod having an inverted T-shaped cross section and arranged in a longitudinally extending groove machined in the die-holding cylinder. The locking rod is displaceable in the axial direction between a locked position and an unlocked position by means of a spindle arranged corresponding to the axial end of the die-holding cylinder. In the locked position, the locking rod enters a transverse recess in an arcuate rib attached to the inner surface of the template and extending in the circumferential direction. That is, this is also a purely mechanical system, in which the axially extending rod is displaced by acting on the rod at the axial end of the die-holding cylinder. In the case of US-5003854-A, the rod is displaced by the rotation of the spindle. A potential disadvantage of this system relates to the need to carefully position the template on the die-holding cylinder so that the arcuate rib is correctly inserted into the corresponding circumferentially extending groove in the surface of the die-holding cylinder.

[0006] US-6925923-B2 discloses a fluid-actuated, typically pneumatically-actuated attachment system comprising a double-acting pneumatic cylinder in which a piston is slidably arranged so that it can slide in an axial direction of the pneumatic cylinder (corresponding to a radial direction of a die-holding cylinder). The piston is selectively driven axially outward (upward in the figure) or axially inward (downward in the figure) (i.e. radially outward or radially inward if the die-holding cylinder is considered as a reference), depending on whether the fluid is driven into a lower chamber of the pneumatic cylinder or out of an upper chamber, or vice versa. The piston is attached to a clamping bolt having an elongated rod or column extending in an axial direction of the pneumatic cylinder, i.e. in a radial direction if the die-holding cylinder is considered as a reference. The clamping bolt comprises a free end having a head extending radially outward relative to the shank. On the other hand, the system includes a template, which is provided with a recess in one surface thereof, the recess being provided with an opening, the opening including a wider portion and a narrower portion, the wider portion being shaped and sized to allow the head of a clamping bolt to pass through the wider portion of the opening, and the narrower portion being shaped and sized to not allow the head of the clamping bolt to pass through the narrower portion of the opening, so as to apply a clamping force to the template in the recess. Therefore, after the template is placed on the die holder, the pneumatic cylinder can be activated to first push the clamping bolt outward through the wider portion of the opening in the template. Thereafter, the template is moved in the circumferential direction of the die holder so that the head of the clamping bolt is positioned to correspond to the narrower portion of the opening, and then the pneumatic cylinder is activated in the opposite direction to displace the piston and the clamping bolt axially inward (radially inward if the die holder is used as a reference) so as to apply a clamping force to the template. The surface around the narrower portion of the opening is recessed from the general top surface of the template and is inclined in a manner matching the shape of the bottom portion of the head of the clamping bolt.

[0007] Similarly, an alternative arrangement based on a pneumatic cylinder driving a clamping bolt is known from US-7171885-B1, in which the head interacts with a recess in the template. Here, the pneumatic cylinder is a single-acting pneumatic cylinder, which drives the corresponding clamping bolt outwards while compressing a clamping spring, which exerts an inwardly directed clamping force on the clamping bolt.

[0008] A problem related to the systems known from US-6925923-B2 and US-7171885-B1 is that, due to the complex shape of the opening, the preparation of the opening in the template is a complex process. A further problem is that the application of the clamping force directly to the template corresponding to the recessed area surrounding the narrower part of the opening implies a risk of damaging the template, and / or the need to limit the magnitude of the clamping force. In order to ensure a reliable clamping of the template in order to keep them stable during operation, a considerable clamping force may generally be preferred. A further problem is that in the event of a failure in the operation of the pneumatic cylinder in the clamped state of the template, the mechanism may get stuck and the removal of the clamping bolts may be difficult. A further problem with the system known from US-6925923-B2 is that the pneumatic clamping force may drop (for example, due to an interruption in the electrical energy supply), so that the die holder continues to rotate without the template being properly clamped to the die holder. This may imply a risk that one or more templates are released due to the centrifugal forces acting on them.

[0009] ES-2691168-A1 discloses a system somewhat similar to the one known from US-7171885-B1, but here the clamping bolt is characterized in that the head has an elongated shape matching the shape of the elongated opening in the template. After passing axially outward through the opening, the clamping bolt is rotated 90 degrees about its axis so that it can apply the clamping force to the template. Here again, the problem is that the clamping bolt applies the clamping force directly to the surface of the template. Moreover, the combination of axial and rotational movement means a relatively complex mechanism with a large number of moving parts. This increases complexity, cost and risk of failure. Summary of the invention

[0010] A first aspect of the invention relates to a clamping device for clamping a template to a die holding cylinder of a rotary die cutting machine, i.e. a rotary die cutter. The clamping device comprises a fluid pressure cylinder (such as a pneumatic cylinder or a hydraulic cylinder) having an axially displaceable piston. A clamping bolt is attached to the piston. The clamping bolt comprises a shank and a head extending radially from the shank. The head may extend from the shank in any manner so that it is suitable for applying a clamping force to the template or, for example, to an interface member, as described below.

[0011] The fluid pressure cylinder is configured to displace the piston axially outwardly in response to fluid injection into the fluid pressure cylinder. The expression "axially outwardly" refers to the axis of the fluid pressure cylinder and is intended to imply that the piston will be driven radially away from the center of the die holding cylinder when the fluid pressure cylinder is incorporated into the die holding cylinder as intended.

[0012] The clamping device also includes a clamping spring arranged to bias the piston axially inwards. Thus, when the piston is displaced axially outwards, it compresses the clamping spring, which biases the piston axially inwards, or, if the axis of the die-holding cylinder is used as a reference, radially inwards. The clamping spring provides a clamping force applied to the die plate and / or the interface member via the clamping bolt.

[0013] According to a first aspect of the invention, the clamping bolt comprises a threaded portion by means of which the clamping bolt is attached to the piston by a threaded connection. The use of a threaded connection facilitates the removal of the clamping bolt from the rest of the assembly by unscrewing, which can be used, for example, in the event of a fault in the operation of the assembly, such as a sticking of the piston or other faults in the operation of the fluid pressure cylinder. Moreover, according to this first aspect of the invention, the head of the clamping bolt is preferably configured to facilitate the application of torque to the clamping bolt to release the clamping bolt from the piston by unscrewing (i.e., by rotating the clamping bolt until the clamping bolt disengages from its attachment to the piston). That is, unlike the bolts known, for example, from US-7171885-B1, the head is in fact preferably configured to facilitate the unscrewing of the bolt. The expression "configured to facilitate application of torque" is to be interpreted broadly as covering essentially any construction suitable for facilitating application of torque, as compared to a simple round flat head of the type known, for example, from US-6925923-B2 and US-7171885-B1, typically due to external shapes and / or recesses in the head facilitating the application of torque through interaction between a tool (e.g. a screwdriver, wrench, etc.) and the head.

[0014] In some embodiments of the present invention, a nut is provided in the piston, and the threaded portion of the clamping bolt engages with the internal thread of the nut. In some embodiments, the nut is arranged in the piston in an axially displaceable manner, and the nut is biased axially outward by a nut support spring. The term "nut support spring" is used to distinguish this spring from the clamping spring. The purpose of this spring is to allow the clamping bolt to be displaced axially inward relative to the piston in the following circumstances: if the piston is displaced axially outward, and the clamping bolt is not positioned corresponding to the wider part of the opening in the interface member, such as described below, but is, for example, below the template away from the through hole. In many potential uses of the present invention, the die holder is provided with a plurality of devices as described above, all of which are activated at the same time, and only some of the devices are placed so that their clamping bolts face the larger part of the opening in the interface member, as described below. When the fluid pressure cylinder is activated, the clamping bolts of the remaining devices will face resistance from above, and this resistance will cause the nut support spring to be compressed, rather than the clamping bolt being pushed upward, which potentially causes damage to the template or the interface member placed in the template, or causes displacement of the template or the interface member.

[0015] In some embodiments of the invention, the nut is prevented from rotating. The nut preferably has an outer shape (e.g., a polygonal cross section) that matches the inner shape (e.g., a polygonal cross section) of a portion of the piston, so that the nut can slide in the axial direction within the piston, but is prevented from rotating. Preventing the nut from rotating can facilitate or ensure easy loosening of the clamping bolt in the event, for example, of a jammed device.

[0016] In some embodiments of the invention, the piston is prevented from rotating relative to the fluid pressure cylinder. This can be used to help ensure that the clamping bolt can be easily loosened in the event of a mechanism failure.

[0017] In some embodiments of the invention, the head of the clamping bolt comprises a portion of a circumference having a non-circular cross section, preferably a polygonal cross section. Using a circumference having a non-circular cross section (such as a polygonal cross section, for example a hexagonal cross section) can facilitate the easy loosening of the clamping bolt using an appropriate tool in the event of a jam of the mechanism.

[0018] In some embodiments of the invention, the head of the clamping bolt comprises a recess suitable for inserting a tool for loosening the clamping bolt. For example, the recess may be a simple linear recess or a star-shaped recess arranged to receive a correspondingly shaped tip portion of a screwdriver, or it may be a polygonal recess, such as a hexagonal recess configured to interact with a hexagonal key (such as an Allen wrench, etc.).

[0019] A second aspect of the invention relates to an assembly comprising a clamping device as described above, the assembly further comprising an interface member configured to be coupled to a template, the interface member comprising an opening having a shape and size designed to allow the head of a clamping bolt to pass through a wider portion of the wider portion, and a shape and size designed to not allow the head of the clamping bolt to pass through a narrower portion, so as to allow the clamping bolt to apply a clamping force to the interface member. By clamping the interface member to the die holder, the template to which the interface member is coupled will likewise become clamped to the die holder.

[0020] Although at first glance the use of an interface member may seem suboptimal, since it represents the use of an additional component that may increase complexity and cost, the inventors have found that such potential disadvantages may be compensated by several potential advantages. First, it is possible to use through holes in the template that are much simpler in design than, for example, those known from US-6925923-B2 and US-7171885-B1, or even do not require such through holes. In particular, it will no longer be necessary to have a through hole of a shape that requires adjustment by allowing the head of the clamping bolt to pass through on the one hand and providing selective retention of the head of the clamping bolt on the other hand. Moreover, the clamping force will no longer be applied by direct contact between the head of the clamping bolt and the surface of the template (e.g., the upper surface in the recess in the template). Instead, the clamping force will be applied to the interface member. Depending on the characteristics of the interface member, the clamping force can be distributed on the contact surface between the interface member and the template, which is determined by parameters such as the shape and size of the interface member, or by the way in which the interface member is connected to the template. Substantial clamping forces, such as greater than 2000 N, such as greater than 2500 N, may be applied to the interface member without any significant risk of damaging the die plate. High clamping forces may be preferred to avoid displacement during high speed rotation of the die holder during operation. The interface member may be manufactured in large quantities in appropriate equipment and recycled for use with successive die plates. Thus, a number of advantages are obtained by using the interface member as the interface between the clamping bolt and the die plate. That is, although the thinking of those skilled in the art generally seems to suggest that minimizing the number of components used is important, it has been found that in the specific context of a rotary die cutter, the advantages obtained by using the interface member outweigh the disadvantages of the potential increased complexity represented by the use of additional components.

[0021] In some embodiments, the interface member is made of metal. Metal interface members can be manufactured at very reasonable cost using conventional metal processing means. At the same time, they can provide good performance in terms of resistance to wear and deformation, for example, also under high clamping forces applied by clamping bolts on the surface of the interface member adjacent to the narrower part of the opening. Moreover, metal interface members can be manufactured with very precise shapes and small tolerances.

[0022] In some embodiments, the interface member is an insert to be inserted into a through hole in the template, the insert comprising a bottom having an opening. In some embodiments, the insert comprises a lateral extending edge portion surrounding at least a portion of an upper end of the insert, the edge portion being configured to bear against an upper surface of the template when the insert is placed in the through hole in the template. The insert may have a tapered shape such that an area of ​​an upper end of the insert is smaller than an area of ​​a lower end of the insert, even when the edge portion is ignored.

[0023] In some embodiments, the interface member is configured to be attached to the inner surface of the template, such as by screws; the term "inner surface" refers to the surface of the template facing the mold holding cylinder when the template is attached to the mold holding cylinder. The clamping device and / or the mold holding cylinder optionally include a recess for receiving at least a portion of the interface member. Optionally, the interface member is arc-shaped.

[0024] One advantage of using an interface member adapted to be attached to the inner surface of the respective template is that there is no need to ensure that a specially adapted opening or through hole is present in the template. Despite the presence of the interface member on the radially inner surface of the template, the presence of one or more recesses in the clamping device and / or in the die holder for receiving the respective interface member allows the template to abut against the surface of the die holder and / or the clamping device. For example, an arcuate interface member extending in the circumferential direction of the die holder can be received in a circumferentially extending recess or groove in the outer surface of the die holder and in the radially outer part of the clamping device, such as in a cover of the clamping device.

[0025] Such an interface member and clamping device can be used to provide reliable clamping, whereby the interface member can also help to correctly position the template relative to the die holder, for example, in the correct position relative to the axis of the die holder. Such an interface member can be compatible with templates without through holes or without through holes with special shapes. The interface member is at least partially positioned in the clamping device and / or in a recess in the die holder, which can help to ensure alignment between the clamping device and the opening in the interface member. When the interface member can slide in the recess in the circumferential direction of the die holder, this can be used to shift the template between the following two positions: a position where the clamping bolt is arranged to correspond to the wider part of the opening in the interface member, and a position where the clamping bolt is arranged so that its handle is in the narrower part of the opening.

[0026] Another aspect of the present invention relates to an assembly for clamping a template to a die holder cylinder of a rotary die cutting machine (i.e., a rotary die cutter). The assembly includes a clamping device including a fluid pressure cylinder (such as a pneumatic or hydraulic cylinder) having an axially displaceable piston. A clamping bolt is attached to the piston. The clamping bolt includes a shank and a head extending radially from the shank. The head can extend from the shank in any manner so that it is suitable for applying a clamping force to the template or, for example, an interface member, as described below.

[0027] The fluid pressure cylinder is configured to displace the piston axially outwardly in response to fluid injection into the fluid pressure cylinder. The expression "axially outwardly" refers to the axis of the fluid pressure cylinder and is intended to imply that the piston will be driven radially away from the center of the die holding cylinder when the fluid pressure cylinder is incorporated into the die holding cylinder as intended.

[0028] The device also includes a clamping spring arranged to bias the piston axially inwards. Thus, when the piston is displaced axially outwards, it compresses the clamping spring, which biases the piston axially inwards, or, if the axis of the die holder is used as a reference, radially inwards. The clamping spring provides a clamping force applied to the die plate and / or the interface member via the clamping bolt.

[0029] According to this aspect of the invention, the assembly further comprises an interface member configured to be coupled to the template, the interface member comprising an opening having a shape and size designed to allow the head of the clamping bolt to pass through the wider portion, and a shape and size designed to not allow the head of the clamping bolt to pass through the narrower portion, so as to allow the clamping bolt to apply a clamping force to the interface member. What has been explained about the interface member and its possible embodiments with respect to the above-mentioned second aspect of the invention also applies to this aspect of the invention.

[0030] Yet another aspect of the present invention relates to a die-cutting machine comprising a die-holding cylinder and a plurality of clamping devices or assemblies as described above, wherein the clamping devices are inserted into recesses in the die-holding cylinder.

[0031] In some embodiments, the die cutting machine further comprises a plurality of die plates, wherein the assembly is an assembly comprising at least one interface member as described above, and wherein:

[0032] - each template comprises a plurality of through holes, wherein the interface members of at least some of the components are arranged in at least some of the through holes, or

[0033] - An interface member in which at least some of the components are attached to the inner surface of at least one template, wherein the interface member is arranged to fit into a recess in the clamping device and / or a recess in the die holder. This can be used to provide a reliable clamping, whereby the interface member can also help to correctly position the template relative to the die holder. Such an interface member can be compatible with the template without a specially designed through hole and helps to ensure alignment between the clamping device and the opening in the interface member.

[0034] Another aspect of the present invention relates to a method for preparing a die-cutting machine, comprising the following steps:

[0035] Providing a die holding cylinder having a plurality of recesses;

[0036] Provide multiple templates;

[0037] arranging a clamping device of an assembly as described above in each of at least some of the recesses;

[0038] and:

[0039] Arranging an insert as described above in each of at least some of the through holes in at least one template; or

[0040] At least one interface member as described above is attached to the inner surface of at least one formwork. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to complete the description and to provide a better understanding of the invention, a set of drawings is provided. Said drawings form an integral part of the specification and illustrate embodiments of the invention, which should not be interpreted as limiting the scope of the invention, but only as examples of how the invention may be performed. The drawings include the following:

[0042] Figure 1 is a schematic exploded view of a portion of a die cutting machine (ie, a so-called die cutter) according to a first embodiment of the present invention.

[0043] Figure 2 is a perspective view of the clamping device of the assembly according to this embodiment of the present invention.

[0044] Figure 3 is a perspective exploded view of the clamping device.

[0045] 4A to 4D are perspective top view, perspective bottom view, top view and cross-sectional side view of the interface member of the assembly according to this embodiment of the present invention.

[0046] FIG. 5A to FIG. 5D is a cross-sectional side view of a portion of a die cutting machine according to this embodiment of the present invention.

[0047] Figure 6 is a cross-sectional side view of a portion of a die cutting machine according to this embodiment of the present invention.

[0048] Figure 7 is a cross-sectional side view of a portion of the die cutting machine of the same embodiment, but from a different angle.

[0049] FIG. 8A to FIG. 8C 2 are a perspective exploded view and a cross-sectional side view, respectively, of a portion of a die cutting machine according to another embodiment of the present invention.

[0050] 9A to 9C 2 are a perspective exploded view and a cross-sectional side view, respectively, of a portion of a die cutting machine according to yet another embodiment of the present invention. DETAILED DESCRIPTION

[0051] Figure 1A portion of a die-cutting machine comprising a die-holder 3 and a plurality of templates is schematically shown, with a portion of one template 4 being shown. For example, the die-holder 3 may support two or more templates 4, each having a curved shape adapted to the outer shape of the die-holder 3, as is known in the art. The die-holder is typically a metal cylinder provided with a plurality of recesses 31 distributed on its surface. One of these recesses 31 is located at Figure 1 Each template 4 generally includes a plurality of through holes 41, one of which is Figure 1 An interface member in the form of a metal insert 2 is arranged in at least some of these through holes 41 , the insert comprising an edge that rests on the upper surface of the corresponding template 4 .

[0052] A clamping device 1 is arranged in each of at least some of the recesses 31 in the die holder 3. The clamping device comprises a generally disc-shaped cover 17 provided with a plurality of holes 171 distributed around its circumference for receiving screws or bolts ( Figure 1 One of these bolts 173 is shown in Figure 7 ) for attaching the clamping device 1 to the die holder 3 so that it will be firmly held in the corresponding recess 31. Figure 2 and Figure 3 The clamping device 1 better shown in the figure comprises a fluid pressure cylinder 11, such as a pneumatic or hydraulic cylinder, in which a piston 12 comprises a nut 15, to which a clamping bolt 13 is threadedly connected. The fluid pressure cylinder 11 is configured to displace the piston 12 together with the nut 15 axially outward (radially outward if the axis of the die holding cylinder is considered as a reference) when the fluid pressure cylinder is activated by introducing a fluid in a chamber of the fluid pressure cylinder. The piston 12 (and the nut 15 together with it) is biased axially inward by a clamping spring 14. The clamping bolt 13 comprises a shank 13B and a head 13A extending radially outward from the shank 13B. The bottom surface of a part of the head is intended to contact a surface of the insert 2 so as to apply a clamping force to the insert 2 for clamping the template to the die holding cylinder 3. The clamping force is applied by the clamping spring 14. As shown Figure 3 As shown, the nut 15 has a hexagonal cross section on the outside, and the nut is slidably arranged in a hole 122 in a central shaft portion 121 of the piston 12. The central shaft portion 121 is surrounded by a spiral clamping spring 14. The hole 122 has a hexagonal cross section that matches the external shape of the nut 15, so that the nut is prevented from rotating, while it can slide in the axial direction, as will be described in more detail below. The nut is biased axially outward by a nut support spring 16 arranged in the piston 12.

[0053] The shank 13B of the clamping bolt 13 has a threaded end section 13C at the end opposite to the head 13A (i.e. at the axially innermost end). This end section 13C is threadedly engaged with the threaded hole 151 of the nut 15. The head 13A of the clamping bolt has an upper part with a hexagonal cross-section on the outside, so as to facilitate the application of torque using a wrench or other suitable tool. In the event that the mechanism becomes stuck, for example, in its clamped state, the bolt 13 can be removed by unscrewing the bolt 13 from the nut 15. This operation is facilitated by the fact that the head has a shape that facilitates the application of torque using a wrench, while the nut 15 is prevented from rotating relative to the piston 12, as described above. In addition, as Figure 3 As shown, the outer wall 123 of the piston 12 extending angularly around the piston includes a vertically extending slot 123A. In the installed state, the slot receives the protrusion 172 of the cover 17 (see Figure 7 ). Therefore, the piston is also prevented from rotating about its axis.

[0054] The fluid pressure cylinder 11 is provided at its upper end with a circumferential flange 110 provided with a first set of holes 111 for receiving screws or bolts 173 inserted via holes 171 in the cover (one of these bolts is in the Figure 7 ), and a second set of holes 112 for receiving screws or bolts 174 for attaching the fluid pressure cylinder 11 to the cover 17 (one of these screws or bolts 174 is in Figure 7 ).

[0055] 4A to 4D An insert 2 is schematically shown forming part of an assembly according to an embodiment of the present invention. The insert may be of any suitable material, for example metal. Figure 4AThe insert is shown open at its top end. The bottom end is partially closed by a base having an opening 20, which includes a wider portion 21 and a narrower portion 22. The wider portion is sized and shaped to allow the head 13A of the clamping bolt 13 to pass through, while the narrower portion is shaped and sized not to allow the head 13A of the clamping bolt to pass through, but is wide enough to accommodate the shank 13B of the clamping bolt. Thus, in operation, the clamping bolt can be moved axially outwards by the displacement of the piston 12 caused by the actuation of the fluid pressure cylinder 11, so that the head enters the insert 2 via the wider part 21 of the opening 20, after which the insert 2 is displaced laterally or angularly (e.g. in the circumferential direction of the die-holding cylinder) so that the shank 13B enters the narrower part 22 of the opening, after which the fluid pressure cylinder can be operated to discharge the fluid from the chamber to allow the piston 12 to descend axially inwards, pushed by the clamping spring 14, until the head 13A of the clamping bolt 13 abuts against the inner surface 23 of the insert around a portion of the narrower part 22 of the opening 20. Thus, the clamping bolt 13 transmits the clamping force applied by the clamping spring 14 to the insert 2. Thus, the clamping force applied in this way by several clamping bolts associated with different assemblies serves to firmly clamp the template 4 provided with the insert 2 to the die-holding cylinder 3.

[0056] As shown, the insert 2 is partially wedge-shaped so that it narrows towards its bottom end. It is also provided with a transversely extending edge or flange portion 24 around a portion of its circumference to allow secure retention when placed in a corresponding through hole in the template.

[0057] FIG. 5A to FIG. 5D Some of the above-described components are schematically shown at different moments in the operation of a clamping mechanism of a rotary die cutter according to an embodiment of the present invention.

[0058] Figure 5A The clamping device is shown with the piston 12 in an axially retracted position and the helical clamping spring 14 in its maximum extended state. The clamping bolt 13 is attached to a nut 15 which is retained within the piston by a circumferentially projecting rim or projection 152 which abuts the upper portion of the inner surface of the piston adjacent the lower end of the hexagonal hole 122. The nut 15 is biased upward (i.e. axially outward) by a nut support spring 16, also housed within the piston 12. The template 4 has been applied to the barrel and the insert 2 placed in the through hole in the template is placed so that the wider portion 21 of the opening 20 in the insert is positioned axially above the head 13A of the clamping bolt.

[0059] exist Figure 5B In the embodiment, the fluid pressure cylinder has been activated by injecting fluid into the chamber 113 defined in part by the lower surface of the piston, so that the piston has been displaced axially outward (in Figure 5BThe clamping spring 14 is compressed and the head 13A of the clamping bolt is pushed through the wider portion 21 of the opening in the insert 2.

[0060] exist Figure 5C In the embodiment shown in FIG. 2 , the template 4 and the insert 2 have been displaced relative to the clamping bolt so that the shank 13B of the clamping bolt has entered the narrower portion 22 of the opening.

[0061] exist Figure 5D In the embodiment, fluid has been allowed to flow out of chamber 113 so as to reduce the pressure in the chamber, thereby allowing piston 12 to move axially inward (in Figure 5D ) in the middle. Figure 5D The arrangement is shown at the end of this movement, i.e. the head 13A of the clamping bolt abuts against the inner surface 23 of the insert 2, and the circumferential protrusion 152 of the nut abuts against the inner top surface of the adjacent hole 122 of the piston 12, thereby preventing further extension of the clamping spring. The pressure applied by the clamping spring 14 at this stage therefore represents the clamping force applied by the head 13A of the clamping bolt to the insert 2. Due to the use of the insert 2, considerable clamping forces can be applied, for example clamping forces greater than 2000N, for example clamping forces greater than 2500N, without any significant risk of damaging the template.

[0062] Usually, when the template is applied to the die holder, it is difficult or impossible to provide axial alignment between all clamping bolts and corresponding inserts. This means that if all fluid pressure cylinders are activated to axially displace the pistons outward, some clamping bolts will not be able to leave through the corresponding through holes in the template. Figure 6 An example of a clamping device according to an embodiment of the invention is shown, in which the head 13A of the clamping bolt does not face the opening in the template 4. When the fluid pressure cylinder 11 is activated and the piston 12 is pushed upward, the head 13A of the clamping bolt will abut against the inner surface of the template 4. When the piston continues to move upward, the nut support spring 16 will be compressed. In this way, damage or displacement of the clamping bolt to the template 4 can be avoided.

[0063] FIG. 8A to FIG. 8C Another embodiment of the present invention is shown, in which the interface member 2A is a rib member having an arcuate shape, instead of using an insert 2 as described above, which can be attached to the corresponding template 4 by any suitable means (for example, by screws 42), such as Figure 8BSchematically shown in . The arcuate shape of the interface member 2A corresponds to the arcuate shape of the radially outer part of the die holding cylinder 3. The cover 17 of the clamping device 1 is provided with a recess 17A, and the die holding cylinder 3 is also provided with a recess 3A. The recesses 17A and 3A form a continuous recess 3A+17A+3A, which extends in the circumferential direction of the die holding cylinder and is arranged to receive the interface member 20A, thereby ensuring that its opening 20A will be correctly positioned in the axial direction of the die holding cylinder 3 relative to the head 13A of the clamping bolt. By moving the template 4 in the circumferential direction of the die holding cylinder, the shank 13B of the clamping bolt 13 can be moved from the wider part 21A of the opening 20A in the interface member 2A to the narrower part 22A, and vice versa. What has been explained about the insert 2 also applies to the arcuate interface member 2A, with necessary changes. The head 13A of the clamping bolt is accessible from above, i.e. from the radially outside of the template 4, via the opening 41 in the template 3. An advantage of this embodiment is that the interface member 2A does not have to be adapted to the opening 41 in the template, since it does not fit into it: the interface member 2A is simply attached to the radially inner surface of the template, e.g. with screws.

[0064] 9A to 9C Shown with FIG. 8A to FIG. 8C A somewhat similar implementation of , but it does not have FIG. 8A to FIG. 8C On the other hand, the opening 20B intended to receive the clamping bolt 13 is in the 9A to 9C The interface member 2B of the embodiment has FIG. 8A to FIG. 8C The configuration of the corresponding opening 20A of the embodiment is different: FIG. 8A to FIG. 8C The opening 20A of the embodiment has the same cross section throughout its entire radial extension (with the die holder 3 as a reference), that is, although the opening 20A has the same shape at its radially outer or "upper" end as at its radially inner or "lower" end, 9A to 9C The opening 20B of the embodiment has a different shape at its radially outer end than at its radially inner end. More specifically, the wider portion 21B and the narrower portion 22B of the opening are formed in a bottom 23B of the opening 20B that is recessed from its radially outer end, thereby providing a space that can accommodate the head 13A of the clamping bolt between the bottom 23A and the template 4, as shown in FIG. Fig.9A and 9B Best shown. In order to access the heads 13A of the clamping bolts from above, it is first necessary to remove the template 4. The advantage of this embodiment is that it does not require any openings in the template above the clamping bolts 13.

[0065] In this document, the term "include" and its derivatives (such as "including", etc.) should not be understood in an exclusive sense, that is, these terms should not be interpreted to exclude the possibility that the described and defined contents may include other elements, steps, etc.

[0066] The present invention is obviously not limited to the specific embodiments described herein, but also covers any changes (e.g., with respect to the choice of materials, dimensions, components, configurations, etc.) that may be considered by a person skilled in the art within the general scope of the invention as defined in the claims.

Claims

1. A clamping device for clamping a die plate on a die holding cylinder of a rotary die cutting machine, the clamping device (1) comprising a fluid pressure cylinder (11) having an axially displaceable piston (12), a clamping bolt (13) being attached to the piston (12), the clamping bolt (13) comprising a shank (13B) and a head (13A) extending radially from the shank (13B), in, The fluid pressure cylinder (11) is configured to displace the piston (12) axially outward in response to fluid being injected into the fluid pressure cylinder (11), The clamping device further comprises a clamping spring (14) arranged to bias the piston axially inwardly. Features The clamping bolt (13) comprises a threaded portion (13C) through which the clamping bolt is attached to the piston (12) by means of a threaded connection.

2. The clamping device according to claim 1, wherein: The head (13A) of the clamping bolt (13) is configured to facilitate application of torque to the clamping bolt to release the clamping bolt from the piston by loosening.

3. The clamping device according to claim 1 or 2, wherein: A nut (15) is arranged in the piston, and the threaded portion (13C) of the clamping bolt (13) is meshed with the internal thread of the nut (15).

4. The clamping device according to claim 3, wherein: The nut (15) is arranged in the piston (12) in an axially displaceable manner, and the nut (15) is biased axially outward by a nut supporting spring (16).

5. The clamping device according to claim 3 or 4, wherein: The nut is prevented from rotating, and wherein the nut (15) preferably has an outer shape matching an inner shape of a portion of the piston (12) such that the nut can slide in an axial direction within the piston but is prevented from rotating.

6. A clamping device according to any one of the preceding claims, wherein: The piston (12) is prevented from rotating relative to the fluid pressure cylinder.

7. A clamping device according to any one of the preceding claims, wherein: The head (13A) of the clamping bolt (13) comprises a portion of a circumference having a non-circular cross-section, preferably having a polygonal cross-section.

8. A clamping device according to any one of the preceding claims, wherein: The head (13A) of the clamping bolt (13) comprises a recess suitable for inserting a tool for loosening the clamping bolt.

9. An assembly comprising a clamping device according to any one of the preceding claims, wherein: The assembly also includes an interface member (2, 2A, 2B) configured to be connected to the template, the interface member including an opening (20, 20A, 20B), the opening having a wider portion (21, 21A, 21B) and a narrower portion (22, 22A, 22B), the wider portion being shaped and sized to allow the head (13A) of the clamping bolt (13) to pass through the wider portion (21, 21A, 21B), and the narrower portion being shaped and sized to not allow the head (13A) of the clamping bolt (13) to pass through the narrower portion (22, 22A, 22B), so as to allow the clamping bolt (13) to apply a clamping force to the interface member (2, 2A, 2B).

10. The assembly according to claim 9, wherein: The interface components (2, 2A, 2B) are made of metal.

11. An assembly according to any one of claims 9 and 10, wherein The interface member is an insert (2) to be inserted into a through hole in a template, the insert comprising a bottom with an opening (20).

12. The assembly according to claim 11, wherein The insert (2) includes a transversely extending edge portion (24) surrounding at least a portion of an upper end of the insert, and the edge portion (24) is configured to be supported on the upper surface of the template when the insert (2) is placed in a through hole in the template.

13. An assembly according to any one of claims 9 and 10, wherein: The interface members (2A, 2B) are configured to be attached to the inner surface of the template, wherein the clamping device (1) and / or the mold holding cylinder optionally include a recess (17A, 17B; 3A, 3B) for receiving at least a portion of the interface members (2A, 2B), and wherein the interface members (20A, 20B) are optionally arc-shaped.

14. A die-cutting machine, comprising a die-holding cylinder (3) and a plurality of clamping devices according to any one of claims 1 to 8 and / or a plurality of assemblies according to any one of claims 9 to 13, wherein: The clamping device (1) is inserted into a recess (31) in the die-holding cylinder (3).

15. The die-cutting machine according to claim 14, further comprising a plurality of templates (4), wherein: The die-cutting machine comprises a plurality of components according to any one of claims 9 to 13, and wherein: - each template comprises a plurality of through holes (41), wherein the interface members (2) of at least some of the components are arranged in at least some of the through holes (41), or - wherein the interface members (2A, 2B) of at least some of the components are attached to the inner surface of at least one of the templates, wherein the interface members (2A, 2B) are arranged to fit into recesses (17A, 17B) in the clamping device (1) and / or recesses (3A, 3B) in the mold holding cylinder (3).

16. A method for preparing a die-cutting machine, the method comprising the steps of: Providing a mold holding cylinder (3) having a plurality of recesses (31); Provide multiple templates (4); arranging the clamping device (1) of the assembly according to any one of claims 9 to 13 in each of at least some of the recesses (31); as well as: Arranging an insert (2) as defined in any one of claims 11 and 12 in each of at least some of the through holes (41) in at least one of the templates (4); or At least one interface member (2A, 2B) as defined in claim 13 is attached to the inner surface of at least one of the templates (4).

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