Sheet processing machines

Abstract

A sheet material processing machine having a conveying mechanism for moving sheets along a processing direction of the sheet material processing machine and a waste discharge device (36) for releasing the sheets. The conveying mechanism comprises a sheet material processing element (28) for moving the sheets, the sheet material processing element (28) comprising at least one sliding element (54). The sheet material processing element (28) is adapted to release the sheets when passing through the waste discharge device (36). The waste discharge device comprises at least one alignment element (38) adapted to interact with the at least one sliding element (54) to minimize deformation of the sheet material processing element (28) when passing through the waste discharge device (36).

Description

Technical Field

[0001] The present invention relates to a sheet material processing machine having a waste material discharge device. Background Art

[0002] Sheet processing machines, also known as converting machines, are used in the packaging industry to convert raw materials such as cardboard, paper, or foil into intermediate or finished products, typically in sheet form. Converting operations may include, for example, printing, cutting, creasing, blanking, punching, and / or folding and gluing. Typically, individual operations are performed in subsequent processing stations of the sheet processing machine, with the sheets being transported from one processing station to the next via a conveyor mechanism.

[0003] For example, in die-cutting machines, so-called blanks are obtained from sheets made of raw material. The blanking operation involves, for example, using a blanking tool to break the score in the sheet, which was already formed in a previous processing step, thereby pushing the blank downward into a stacking area for collecting the blanks. Consequently, after the blanking operation, the waste sheet remains connected to the conveyor mechanism and needs to be removed in a subsequent waste discharge station (also called a waste discharge station).

[0004] Modern sheet processing machines are capable of producing a high output of sheets, ie a high processing speed. In order to achieve such processing speeds, it is desirable to release the waste sheets from the conveyor in a dynamic manner, ie it is desirable to release the waste sheets without stopping the conveyor.

[0005] However, high processing speeds result in high forces acting on conveyor components, such as centrifugal forces at the conveyor's bends. This effect becomes more pronounced the larger the sheet size to be processed. Therefore, for large sheet sizes, known systems involve stopping the conveyor and removing the waste sheet with additional moving elements. This limits the maximum achievable processing speed and requires complex mechanisms.

[0006] WO2017 / 153056A1 discloses a discharge mechanism for removing waste during operation in a sheet material processing machine. The discharge mechanism includes a comb-like structure that is configured to switch between a first, low-speed position and a second, high-speed position. In the high-speed position, the center of the comb is positioned rearward to compensate for deformation of the processed sheet material and components of the conveyor mechanism. However, the discharge mechanism and the sheet material processing machine incorporating such a mechanism require complex and costly designs. Summary of the Invention

[0007] The object of the present invention is to provide a simple mechanism for waste discharge in a sheet material processing machine, preferably allowing high processing speeds, even for large sheet sizes.

[0008] The object of the present invention is achieved by a sheet material processing machine having a conveyor mechanism for moving sheets along a processing direction of the sheet material processing machine and a waste discharge device for releasing the sheets. The conveyor mechanism comprises a sheet material handling element for moving the sheets, the sheet material handling element comprising at least one sliding element. The sheet material handling element is adapted to release the sheets when passing through the waste discharge device. The waste discharge device comprises at least one alignment element adapted to interact with the at least one sliding element in order to minimize deformation of the sheet material handling element when passing through the waste discharge device.

[0009] The present invention is based on the idea of providing a simple and inexpensive mechanical device for maintaining the shape of a sheet processing element as it passes through a waste discharge device. The sliding interaction between at least one sliding element of the transport mechanism and at least one alignment element of the waste discharge device minimizes wear on these components while reliably stabilizing the shape of the sheet processing element, thereby enabling high processing speeds of the sheet processing machine.

[0010] By minimizing deformation of the sheet handling element, mechanical stresses in the sheet handling element may be reduced, thereby minimizing the risk of damaging and / or breaking the sheet handling element, in particular when using high processing speeds.

[0011] At least one sliding element is preferably arranged at the leading edge of the sheet processing element. The term "leading edge" refers to the portion of the sheet processing element that is arranged in front of the sheet processing element relative to the processing direction of the sheet being processed in the sheet processing machine. By providing at least one sliding element at the leading edge, at least one alignment element of the waste discharge device can interact with the sliding element before any other portion of the sheet processing element comes into contact with the waste discharge device. This allows for a simplified shape and size of the alignment element and ensures that any deformation of the sheet processing element can be minimized or even prevented once the sheet processing element comes into contact with the waste discharge device.

[0012] The leading edge particularly defines the longitudinal direction of the sheet processing element, and the at least one sliding element is particularly arranged in the longitudinal direction between a first end and a second end of the sheet processing element, the second end being opposite the first end in the longitudinal direction. Deformations along the leading edge of the sheet processing element can thus be particularly prevented or at least minimized.

[0013] The sheet material handling element has in particular a length in the longitudinal direction of 106 cm or more, for example a length in the longitudinal direction of 140 cm to 170 cm.

[0014] The length of the sheet processing element in the longitudinal direction corresponds in particular to the size of the sheet to be processed by the sheet processing machine. Therefore, the sheet processing machine according to the invention allows in particular to process large-sized sheets, because the sheet processing element can be stabilized by at least one alignment element of the waste discharge device.

[0015] In order to further minimize deformation of the sheet handling elements or to prevent such deformation altogether, the sheet handling elements may comprise a plurality of sliding elements, which are in particular arranged symmetrically around the middle of the length direction of at least one sheet handling element.

[0016] In other words, the plurality of sliding elements are in particular arranged such that the sheet processing element substantially has a mirror plane in the centre with respect to the length direction of the arrangement of the sliding elements and perpendicular to the length direction.

[0017] In one variant, the sliding elements are arranged equidistant from one another along the length of the leading edge. This provides a particularly uniform distribution of the positions at which the at least one alignment element can interact with a plurality of sliding elements.

[0018] Preferably, the at least one sliding element is a roller. By using a roller as the sliding element, any force acting on the sliding element can be converted into a circular motion of the roller, thereby eliminating or at least minimizing the risk of damaging the sliding element when interacting with the at least one alignment element.

[0019] The sheet handling element may comprise at least one clamping element displaceable between a sheet clamping state and a sheet releasing state, the at least one clamping element being arranged in particular at a trailing edge of the sheet handling element, the trailing edge being opposite the leading edge.

[0020] The at least one clamping element may be responsible for securing the sheet material while it is moved by the transport mechanism along the processing direction through the processing stations of the sheet material processing machine.

[0021] Thereby, the at least one sheet handling element may in particular be a gripper bar, preferably a gripper bar comprising a plurality of gripping elements.

[0022] Similar to the sliding elements, the clamping elements may be arranged symmetrically around the middle of the length direction of at least one sheet handling element to allow clamping of the sheet in an evenly distributed manner.

[0023] By arranging the at least one clamping element on the opposite side of the sheet handling element relative to the at least one sliding element, the at least one clamping element does not interfere with the at least one sliding element. In addition, the only contact between the sheet handling element and the sheet can be easily achieved via the at least one clamping element, i.e., the sheet does not need to come into contact with any other part of the sheet handling element.

[0024] At least one alignment element of the waste discharge device may comprise a sliding surface for interacting with at least one sliding element. In other words, the movement direction of the at least one sliding element and thus the movement direction of the sheet processing element may be at least partially defined by the course of the sliding surface.

[0025] Preferably, the sliding surface has a curved shape.

[0026] For example, the sliding surface can be arranged to coincide with the direction of travel of the sheet processing elements as they pass through the waste discharge station. This means that the transport mechanism can travel around a loop, with the sheet being moved by the sheet processing elements along substantially half the loop in the processing direction, and can then travel in the opposite direction, without a sheet, along substantially the other half of the loop, back to the starting position to grip the next sheet to be processed. The sliding surface can be arranged at the turning point between the two halves of the loop at the waste discharge device.

[0027] Preferably, the waste discharge device comprises an alignment element for each sliding element of the sheet material processing element, each alignment element being associated with a sliding element. Thus, each sliding element present at the sheet material processing element can help prevent or at least minimize deformation of the sheet material processing element when passing through the waste discharge device.

[0028] The at least one alignment element may be a cam. Cams are inexpensive and are available in a variety of sizes and shapes to provide the desired interaction between the at least one sliding element and the cam. Furthermore, they can be designed to reduce the space required.

[0029] The waste discharge device may further include a comb having a plurality of teeth. The comb is configured to retain waste sheets delivered by the conveyor mechanism to the waste discharge device while allowing the sheet processing elements to pass through. The teeth of the comb are particularly arranged so that at least one gripping element of at least one sheet processing element can pass through the comb.

[0030] By minimizing deformation of the sheet handling element, the waste discharge device can use a comb with a fixed shape.

[0031] The transport mechanism preferably moves the sheets from a loading station of the sheet processing machine to a waste discharge station of the sheet processing machine including a waste discharge device.

[0032] Preferably, the transport mechanism comprises a plurality of sheet material processing elements. This allows for a higher processing speed of the sheet material processing machine. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Further advantages and features of the present invention will become apparent from the following description of the invention and the accompanying drawings which show non-limiting exemplary embodiments of the invention and in which:

[0034] - Figure 1 A sheet material processing machine according to the invention is schematically shown;

[0035] - Figure 2 Shown Figure 1 A perspective view of a waste discharge device of a sheet material processing machine;

[0036] - Figure 3 Shows the interaction with sheet handling elements Figure 2 waste discharge device; and

[0037] - Figure 4 Shown through Figure 3 The cutting part of the waste discharge device. DETAILED DESCRIPTION

[0038] Figure 1 Schematically shown is a sheet processing machine 10 that enables blanks to be cut from a continuous sheet 12. These blanks are typically intended to be subsequently folded and glued to form packaging boxes. However, the sheet 12 may typically be made of, for example, paper, cardboard, foil, composite materials thereof, or any other material conventionally used in the packaging industry.

[0039] The sheet processing machine 10 comprises a series of processing stations arranged in parallel but interdependently to form a unified assembly. The processing machine 10 comprises a loading station 14, followed by a cutting station 16 (also commonly referred to as a punching station), the cutting station 16 comprising, for example, a die press or flatbed press 18 in which the sheet 12 is deformed by cutting, a waste removal station 20 in which the bulk of the waste portion is stripped off, a blank separation station 22 (also commonly referred to as a receiving station) for separating the blanks (or blanking operations) by a blanking tool 23, and a waste discharge station 24 for removing the remaining waste sheet of the punched sheet 12.

[0040] The number and nature of the processing stations may vary depending on the nature and complexity of the converting operations to be performed on the sheet 12 .

[0041] The sheet material processing machine 10 also has a conveying mechanism 26 which, in the embodiment shown, is a conveying device, making it possible to move each sheet material 12 individually from the outlet of the loading station 14 to the waste material discharge station 24 .

[0042] The conveyor uses a series of sheet handling elements 28 mounted so as to be movable by means of two turns of chain 30 placed laterally on each side of the sheet processing machine 10. Each turn of chain 30 travels around a loop that allows the sheet handling elements 28 to follow a trajectory that successively passes through the cutting station 16, the waste removal station 20, the blank separation station 22 and the discharge station 24.

[0043] Each sheet handling element 28 travels substantially the first half of its travel on an outward path in a substantially horizontal plane between the driven wheel 32 and the idler wheel 34, and then travels substantially the second half of its travel on a return path within the top portion of the sheet processing machine 10. Once returned to the driven wheel 32, each sheet handling element 28 is then able to grip a new sheet 12 at its leading edge.

[0044] In the embodiment shown, the sheet handling element 28 is a so-called gripper bar.

[0045] exist Figure 1 In FIG. 1 , each processing station is shown in the form of two rectangles symbolically representing a top portion thereof and a bottom portion thereof positioned on each side of the plane of movement of the sheet 12 .

[0046] exist Figure 1 The median, transverse (or lateral), longitudinal and vertical directions are indicated by an orthogonal spatial system (T, L, V).

[0047] The terms "upstream" and "downstream" are used with reference to FIG12 in the example Figure 1 The direction of movement is defined by the processing direction shown by the arrow D.

[0048] The waste discharge station 24 further comprises a waste discharge device 36 for releasing the sheets 12 that have been moved from the loading station 14 to the waste discharge station 24 , ie for removing waste sheets.

[0049] Figure 2 A perspective view of the waste discharge device 36 is shown.

[0050] The waste discharge device 36 comprises two alignment elements 38 , each of which is a cam comprising a curved sliding surface 40 .

[0051] The alignment elements 38 are securely mounted to the frame 41 by means of screws 42 , ie the alignment elements 38 are fixed in their position.

[0052] The waste discharge device 36 further includes a comb 44 having a plurality of teeth 46 .

[0053] The comb 44 is formed of a first thin plate 48 and a second thin plate 50 connected by a plurality of fixing elements 52. The first thin plate 48 is made of a plastic material to limit the noise caused by the impact of the sheet material on the comb 44, while the second thin plate 50 is made of metal to provide sufficient mechanical strength to the comb 44. Alternatively, of course, the first thin plate 48 and the second thin plate 50 can be made of plastic or metal, as long as sufficient mechanical strength of the comb 44 is achieved.

[0054] Figure 3 and Figure 4The waste discharge device 36 is shown as one of the sheet handling elements 28 passes by the waste discharge device 36 .

[0055] The sheet handling element 28 has two sliding elements 54 which, in the embodiment shown, are rollers. Each of the sheet handling elements 28 is associated with one of the alignment elements 38 of the waste discharge device 36.

[0056] More specifically, each of the sliding elements 54 is adapted to roll along the sliding surface 40 of the associated alignment element 38 as the sheet handling element 28 passes the waste discharge device 36 .

[0057] Of course, the sheet handling element 28 can in principle have only one or more than two sliding elements 54 .

[0058] The sliding element 54 is arranged at a leading edge 56 of the sheet handling element 28. The leading edge 56 defines a length direction of the sheet handling element 28, wherein the sliding element 54 is arranged at the leading edge 56 between a first end 58 and a second end 60 of the sheet handling element 28.

[0059] The lengthwise direction extends along the transverse direction T and defines a dimension of the sheet 12 along the transverse direction T, which dimension can be controlled by the sheet processing machine 10 .

[0060] Opposite the leading edge 56 , the sheet handling element 28 includes a plurality of clamping elements 62 at a trailing edge 64 of the sheet handling element 28 .

[0061] The clamping element 62 can be shifted between a sheet clamping state and a sheet releasing state, wherein the switching between these two states is accomplished at the waste discharge station 24 by the interaction of the opening mechanism 66 of the sheet handling element 28 and the (not shown) opening cam of the waste discharge device 36.

[0062] Each of the clamping elements 62 includes two arms 63 that are pressed against each other in the clamped state, for example, by a force applied by a spring mechanism (not shown) of the sheet handling element 28. In the sheet release state, the arms 63 of the clamping elements 62 are separated from each other to allow the sheet 12 to be placed between the arms 63. When moving back to the clamped state, the sheet 12 is accordingly pressed between the arms 63 and becomes fixed.

[0063] The sliding element 54 and the clamping element 62 are symmetrically arranged about the middle of the length direction of the leading edge 56 and the trailing edge 64, respectively.

[0064] Hereinafter, the operation mode of the waste discharge device 36 will be described in more detail.

[0065] During operation of the sheet material processing machine 10, the gripping elements 62 of the sheet material handling elements 28 serve to grip the leading edge of the sheet material 12 at the exit of the loading station 14 (see Figure 1 ), i.e. the clamping elements 62 enter their clamping state.

[0066] The sheet 12 is then moved through the processing stations by movement of the sheet handling element 28 along the processing direction D, so that when the sheet handling element 28 reaches the waste discharge station 24 with the waste discharge device 36 , the waste sheet is gripped by the gripping elements 62 .

[0067] As described above, the chain 30 of the conveyor 26 defines an outward path and a return path. The transition between the outward path and the return path is defined by a turning point defined by an idler wheel 34 located at the waste discharge device 36.

[0068] Therefore, by the movement of the chain 30, the sheet processing member 28 is pulled along the turning point.

[0069] Due to the high processing speed of the sheet processing machine 10, centrifugal forces act on the sheet processing element 28. These centrifugal forces will cause deformation of the sheet processing element 28. In particular, the sheet processing element 28 will be deformed into a bow shape, i.e. the sheet processing element 28 will no longer be straight along the length direction.

[0070] However, when the sheet processing element 28 passes the waste discharge device 36 , the sliding elements 54 of the sheet processing element 28 contact the associated curved sliding surfaces 40 , thereby preventing or at least minimizing deformation of the sheet processing element 28 as it passes the waste discharge device 36 .

[0071] In other words, the interaction between the sliding element 54 and the alignment element 38 of the sheet handling element 28 acts like a reinforcement member for the sheet handling element 28 , ensuring that the sheet handling element 28 remains substantially straight along its length as it passes through the waste discharge device 36 .

[0072] When the sheet handling element 28 passes the waste discharge device 36 , the gripping elements 62 at the trailing edge 64 pass between the teeth 46 of the comb 44 .

[0073] Thus, the sheet 12 (more precisely the waste sheet) held by the gripping elements 62 will impact the teeth 46 when the trailing edge 64 passes the comb 44 .

[0074] At the same time, the gripping elements 62 are displaced into their sheet-releasing state by the interaction of the opening mechanism 66 with an opening cam (not shown) of the waste discharge device 36 .

[0075] Thus, as the sheet 12 impacts the comb 44, the sheet 12 is retained as the sheet handling element 28 passes through the waste discharge 36. The retained sheet 12, which is waste, may be collected in the waste discharge station 24 and discarded.

[0076] The sheet material processing machine according to the invention allows, in a simple and inexpensive manner, to prevent or at least minimize deformations experienced by the sheet material processing element 28. This enables the sheet material processing machine 10 to dynamically discharge waste sheets, i.e., even in the case of relatively large sheets 12, without having to stop the transport mechanism 26. Furthermore, no moving parts are required in the waste material discharge device 36 for removing the waste sheets.

Claims

1. A sheet material processing machine having a conveying mechanism (26) for moving a sheet material (12) along a processing direction of the sheet material processing machine (10) and a waste discharge device (36) for releasing the sheet material (12), The transport mechanism (26) comprises at least one sheet handling element (28) for moving the sheet (12), the sheet handling element (28) comprising at least one sliding element (54), The at least one sheet handling element (28) is adapted to release the sheet (12) when passing through the waste discharge device (36), The waste discharge device (36) comprises at least one alignment element (38) having a sliding surface (40), wherein the sliding surface (40) is adapted to interact with the at least one sliding element (54) for minimizing deformation of the at least one sheet handling element (28) when passing through the waste discharge device (36).

2. The sheet material processing machine according to claim 1, wherein the at least one sliding element (54) is arranged at a leading edge (56) of the sheet material processing element (28).

3. A sheet processing machine according to claim 2, wherein the leading edge (56) defines the length direction of the sheet processing element (28), and the at least one sliding element (54) is arranged along the length direction between the first end (58) and the second end (60) of the sheet processing element (28), and the second end (60) is opposite to the first end (58) along the length direction.

4. The sheet material processing machine according to claim 2, wherein the at least one sheet material handling element (28) comprises a plurality of sliding elements (54).

5. The sheet material processing machine according to claim 4, wherein the sliding elements (54) are arranged equidistant from one another along the length direction of the leading edge (56).

6. The sheet material processing machine according to claim 1, wherein the at least one sliding element (54) is a roller.

7. The sheet material processing machine according to claim 2, wherein the at least one sheet material handling element (28) comprises at least one clamping element (62) displaceable between a sheet material clamping state and a sheet material releasing state.

8. The sheet material processing machine according to claim 1, wherein the sliding surface (40) has a curved shape.

9. The sheet material processing machine according to claim 1, wherein the waste discharge device (36) comprises an alignment element (38) for each sliding element (54) of the at least one sheet material processing element (28), each alignment element (38) being associated with a sliding element (54).

10. The sheet material processing machine according to claim 1, wherein the at least one alignment element (38) is a cam.

11. The sheet material processing machine of claim 1, wherein the waste discharge device (36) further comprises a comb (44) comprising a plurality of teeth (46).

12. The sheet processing machine according to claim 1, wherein the conveying mechanism (26) moves the sheet (12) from the loading station (14) of the sheet processing machine (10) to the waste discharge station (24) of the sheet processing machine (10) including the waste discharge device (36).

13. The sheet material processing machine of claim 1, wherein the transport mechanism (26) comprises a plurality of sheet material handling elements (28).

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