GB2459877A

GB2459877A - Die for paperboard blanks, including selectively operable pins

Info

Publication number: GB2459877A
Application number: GB0808353A
Authority: GB
Inventors: Jim Westbrook
Original assignee: Corridoor Ltd
Current assignee: Corridoor Ltd
Priority date: 2008-05-08
Filing date: 2008-05-08
Publication date: 2009-11-11
Also published as: GB0808353D0

Abstract

The array (figures 3A-3F) of pins 108A-108L is held within a frame. In the clamped F2 state the parallel pins are fixed relative to each other. The position of each pin is adjustable along its longitudinal axis when the frame is in an unclamped state. Preferably the pins have mutually engaging splines, a textured surface, a screw thread (128, figure 6) or a resilient coating (126, figure 5). The die preferably also includes a gas flow and adjusting mechanism 116. The pins cut, score and crease the blanks 118.

Description

Pin Matrix Die

Field of the Invention

The present invention relates to a die suitable for cutting and/or creasing sheet materials, for example card, paper, paperboard and corrugated fibreboard.

Background of the Invention

In the packaging industry paperboard (also known as cardboard) and other materials are cut and creased to form blanks that are used to make packaging products such as boxes. Cutting and creasing is commonly performed using a die (also known as a "forme") that is pressed against a material sheet on a high pressure press. Both flat and curved die are used for flat-bed and rotary presses respectively.

A flat die is commonly made from a rigid board (e.g. plywood) on which a pattern of strip-like cutting blades is provided, mounted in channels within the board and projecting from the operative surface. In operation a cardboard sheet is typically placed on a resilient pressing platen in a high pressure press and the cutting blades are pressed through the sheet to cut out a cardboard blank. Before folds can be made in a sheet material it is typically necessary to crease it, in which operations the deformation of the material may be made with or without the penetration of the surface by the die. Creases formed by penetration of the surface of the sheet are also referred to as scoring. Creases are typically made by means of creasing bars or creasing blades that are integrated into the cutting forme. Such creasing bars or blades project from the cutting surface of the forme, but to a lesser extent than cutting blades, and may be less sharp. An example of a typical flat die is described in UK patent application GB2032322A.

Separate die are required for each packaging design to provide the correct pattern of cuts and creases for each different design of blank. Such die are complex, time-consuming and expensive to manufacture. Further, die are substantial in size and require to be stored between uses, necessitating the provision of a significant amount

I

of storage space at a packaging manufacturer's facilities where a large number of different blanks are manufactured.

Thus a need remains in the industry for an alternative design of die cutting and creasing apparatus that is quicker to configure for operation, does not require unique permanent die to be made for each cutting and creasing operation, and which avoids the need for the storage of such die.

Statement of the Invention

It is an object of the present invention to provide a device that overcomes at least some of the disadvantages described above.

In accordance with a first aspect of the present invention there is provided a die suitable for use in the manufacture of paperboard blanks. The die comprises an array of pins and an adjustable frame within which the pins are contained. The pins each have a longitudinal axis and adjacent pins are substantially parallel. The frame is adjustable between a clamped state in which each pin is fixed relative to the adjacent pins, and an unclamped state in which the position of each pin is adjustable along its longitudinal axis relative to the adjacent pins.

The pins have a may have a head, a tip and a body, the bead and the tip being at opposed ends of the body. The tip may be one of pointed, rounded, blunt, flat, conic, frusto-conic, pyramidal, and wedge-like shaped. The heads of the pins may be flat or dimpled.

In an unconfigured state the positions of the tips of the array of pins may correspond with a plane. Alternatively the positions of the tips of the pins may correspond with a curved surface.

The die may be configured to produce one of a cut, a crease or both a cut and a crease in operation.

The pins may be closely packed in an arrangement that is a perpendicular, hexagonally tessellated or triangularly tessellated array.

The cross-section of each pin, perpendicular to its respective longitudinal axis, may be one of circular, square, hexagonal, triangular and star shaped. The bodies of the pins may be provided with splines such that the splines of adjacent pins engage.

The bodies of the pins may be coated with a resilient layer, or may be provided with a textured surface.

The pin matrix may comprise pins of a substantially identical design or of a plurality of different designs. The pin matrix may be sub-divided into a plurality of sub-matrices.

Adjacent pins may abut. Alternatively pins may be individually held by the frame such that they do not abut.

In accordance with a second aspect of the present invention, there is provided a press for cutting and/or scoring. The press comprises a die according to the first aspect of the present invention.

The press may further comprise an adjustment tool. The adjustment too may be capable of adjusting individual pins andlor may be capable of simultaneously adjusting a plurality of pins.

The die may be provided with a gas control system capable of inducing a flow of gas through gaps between pins in the pin matrix.

In accordance with a third aspect of the present invention, there is provided a method of configuring a die or a press as described above. When configured, the positions of the pins are adjusted such that selected pins protrude from the remaining pins.

The method may comprise presenting the pins adjacent to a resilient or deformable material, adjusting the die into an unclamped state, adjusting the positions of selected pins such that they press into or partially penetrate the resilient or deforinable material adjusting the die into a clamped state and removing the die from the resilient or deformable material.

The positions of pins may be adjusted by means of pushing along their respective longitudinal axes. Alternatively in the case where the body of each pin is provided with a screw thread and the head of each pin is provided with rotational engagement means, the positions of the pins may be adjusted by means of rotation about their respective longitudinal axes.

In accordance with a fourth aspect of the present invention, there is provided a method of cutting and/or scoring a sheet with a die or press configured as described above.

The die is pressed against a sheet such that pins pierce the sheet and/or further pins deform the sheet.

A blank may be cut from the sheet, and a further operation may separate the portion of the sheet corresponding to the blank from that portion comprising waste that surrounds the blank. The sheet may be disposed on a resilient cutting platen during the cutting and/or scoring. Alternatively the sheet may be disposed on a belt of resilient material that is driven between pressing operations such that in successive pressing operations the die is operable upon different portions of the belt.

Brief Description of the Drawings

For a better understanding of the present invention and to show more clearly how it may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings, in which: Figure 1 is a schematic illustration of a pin matrix frame according to the present invention.

Figures 2A-2D are schematic cross-sectional views of a pin matrix according to the present invention.

Figures 3A-3F are schematic plan views of pins with different cross-sections or arranged in different arrays, within pin matrices according to the present invention.

Figure 4 is a schematic cross-sectional view of pins with dimpled heads, according to the present invention.

Figure 5 is a schematic cross-sectional view of pins with resilient coatings, according to the present invention.

Figure 6 is a schematic cross-sectional view of pins having heads provided with engagement means for rotation, according to the present invention.

Figures 7A and 7B are schematic cross-sectional views of pins having blunt tips, according to the present invention.

Figure 8 is a schematic cross-sectional views of a curved pin matrix according to the present invention.

Detailed Description of Preferred Embodiments

Figure 1 of the accompanying drawings illustrates a die 100 according to the present invention, comprising a pin matrix 102 held in an adjustable frame 104. The adjustable frame 104 has adjustable ends 106 that are held together under a compressive force Fl. The pins 108 of the pin matrix 102 are held in an arrangement in which their longitudinal axes of adjacent pins are substantially parallel. The pin matrix 102 comprises a two-dimensional array of pins, in which the longitudinal axes are substantially perpendicular to the array.

Figure 2A illustrates a cross-sectional view through a pin matrix 102 according to Figure 1. Each pin 108 comprises a substantially parallel-sided body 110, a tip 112 and a head 114, with the tip and head being at opposite ends of the body. The tip 112 comprises a tapered cutting section, which tapers to a point.

Both Figures 1 and 2A show the pin matrix 102 in an un-configured state, in which all of the pins 108 are positioned such that their tips 112 lie in a planar surface. For use in cutting and/or creasing sheet materials (e.g. cardboard), the pins 108 of the pin matrix 102 are configured with a pattern of protruding pins that corresponds with the required pattern of cuts and/or creases in the sheet against which the die 100 is pressed. Such patterns may be complex, including curves and irregular shapes, as are required for the manufacture of complex blanks.

When the die is in use, the pin matrix is held in a clamped state, in which the pins are held into fixed relative positions. The die 100 in Figures 1 and 2A is clamped by the application of a compressive force Fl applied by the adjustable ends 106 to the pin matrix 102.

However, before it can be used, the un-configured pin matrix 102, as illustrated in Figures 1 and 2A, must be configured with the required pattern of protruding pins.

Figure 2B illustrates the way in which the die 100 may be configured for cutting and creasing. The clamped pin matrix 102 is positioned with the tips 112 of the pins 108 adjacent to a resilient board 118. To enable relative the positions of individual pins 108 to be adjusted relative to surrounding pins and the frame 104, the compressive force Fl holding the pins in the clamped state is at least partially relaxed to a lesser compressive force F2, corresponding with an unclamped state. In this unclamped state the pins remain held together in a substantially parallel arrangement.

In the unclamped state the positions of pins are adjusted to the required positions by means of an adjustment tool 116. The adjustment tool 116 serves to adjust the position of pins by pushing against the head of a selected pin, causing it to protrude from the pin matrix 102 and project into the resilient board 118. In Figure 2B pins 108B to 108F, 1081 and 108K have been adjusted in this way, and the remainder of the pins 108 of the pin matrix 102 remain in the un-configured state, such that their tips 112 remain in substantially a single plane.

Pins 1 08B and 108K are shown adjusted into positions suited to cutting. Pins I 08E and 1081 are shown adjusted into a position suited to creasing. The tip 112 of a pin (e.g. I 08B) adjusted into a cutting position protrudes from the surrounding pin matrix 102 by a greater extent than a pin (e.g. I 08C) adjusted into a creasing position. Once the pattern of pins 108 in the pin matrix 102 has been adjusted to the required configuration the pin matrix 102 is re-clamped. The clamped pin matrix 102 may then be withdrawn from the resilient board 118, with the pins 108 held firmly in place within the frame 104.

In place of a resilient board 118, a deformable material may alternatively be used, such as a polyurethane block.

The configured and clamped die 100 can then be used, for example to perform cutting andlor creasing operations of sheet materials. Such use is illustrated in Figures 2C and 2D, which show the die 100 respectively before and during a cutting and creasing operation. A sheet 120 is placed on a resilient cutting platen 122, and the die 100 is pressed against the sheet, such that the cutting pins I 08B, 1 08F and 108K pierce the sheet, and the creasing pins 1 08C, I 08D, I 08E and 1081 deform the sheet.

Lines of cutting pins form corresponding cut lines in the sheet. Where lines of adjacent cutting pins pierce the sheet they form corresponding cut lines, for example defining the perimeter of a blank that is cut from the original sheet. In the case that a line of cutting pins is aligned with a row of adjacent pins of the pin matrix, the cut may be a complete cut. However, in the case that a line of cutting pins is not aligned with a row of adjacent pins of the pin matrix the cut may be perforated.

Lines of creasing pins form corresponding crease lines in the sheet, such that the blank may be folded along the crease lines, once the cutting and creasing operation is complete. When the die is pressed against the sheet the creasing pins deform the sheet or may pierce part way through the thickness of the sheet. Alternatively the creasing pins may also pierce through the full thickness of the sheet, but to a lesser extent than for a cutting pin, such that only part of the tip 112 of the pins passes through the sheet 120, forming an incomplete cut (that is, a series of perforations), even in the case that a line of creasing pins is aligned with a row of adjacent pins in the pin matrix.

Once a sheet material has been pressed with a die to cut a blank, it is typical that the blank will still be attached to surrounding waste material by small uncut portions of the sheet. The sheet typically undergoes a further operation in which the blank is separated from the surrounding waste.

After the use of the die for pressing blanks of one design from sheets is complete the die requires to be reconfigured with a new pattern of adjusted pins corresponding with the required cutting and/or creasing pattern of another design of blank. Such a step may be performed by positioning the pin matrix just above a resilient surface, and relaxing the compressive clamping force to the unclamped state, such that the pins may freely fall such that their tips all rest on the resilient surface, such that their tips all lie in a plane, as per the unconfigured state illustrated in Figures 1 and 2A. The frame may be repositioning relative to the pin matrix. Once in this unconfigured state the pins may then be configured with a new pattern.

In known die, cutting edges are formed by blades that are fixed into a board. The production of curved or complex shapes requires the use of correspondingly shaped blades. The forming of such blades and fixing to the board is time consuming and leads to die typically being complex and costly to manufacture. In contrast, with a die according to the present invention, it is relatively simple to select any desired cutting or creasing pattern by suitable adjustment of the pins. Consequently the present invention enables the formation of die providing enhanced cutting and creasing patterns with increased complexity over those typically produced by methods

according to the prior art.

As will be appreciated, the adjustment of pins by the adjustment tool can be automated. The operation of the adjustment tool is preferably automated and computer controlled, thereby greatly reducing the time required to manually configure the pins. The adjustment tool may be operated robotically, for example being attached to a robotic arm.

The size of the adjustment tool may be such that it enables single pins to be adjusted, or may instead be greater in size to enable a plurality of pins to be simultaneously adjusted.

Figures 3A-3F illustrate cross-sectional views through the bodies 1 10 of pins of different designs and in different arrangements of pin matrix according to the present invention, corresponding with the cross-sectional line C-C indicated in Figure 2A: * Figure 3A illustrates a cross-section through a pin matrix in which the bodies of the pins are circular in cross-section, and which are arranged in a closely packed, tessellated hexagonal array, corresponding with the pin matrix 102 illustrated in Figure 1.

* Figure 3B illustrates a cross-section through a pin matrix in which the bodies are circular in cross-section, and which are arranged in a perpendicular array.

* Figure 3C illustrates a cross-section through a pin matrix in which the bodies are square in cross-section,. and which are arranged in a perpendicular, tessellated array.

* Figure 3D illustrates a cross-section through a pin matrix in which the bodies are triangular in cross-section (for example, an equilateral triangular cross-section), and which are arranged in a tessellated array.

* Figure 3E illustrates a cross-section through a pin matrix in which the bodies are hexagonal in cross-section, and which are arranged in a tessellated array.

* Figure 3F illustrates a cross-section through a pin matrix in which the bodies are provided with splines (that is axial ridges and grooves on the surface of the body portion, such that the pins have a star-shaped cross-section), such that the splines of adjacent pins engage, and are arranged in a hexagonal array Other cross-sections of the bodies of the pins in the pin matrix are possible and may provide enhanced engagement between adjacent pins, and fall within the scope of the present invention.

The heads 112 of the pins 108 may be flat, as illustrated in Figures 1 and 2. However, to aid centring of the adjustment tool 116 the heads 114 may preferably be shaped to provide enhanced engagement between the tool 116 and the pin 108. For example the head may be dimpled 124, as illustrated in Figure 4.

Successful clamping together of a matrix of pins requires that the bodies of the pins are dimensionally substantially identical, requiring manufacture of the pins within narrow tolerances. To partially relax the tolerances of the manufactured pins, in one embodiment it is envisaged that the bodies 110 of the pins 108 may be coated (or otherwise surrounded) with a resilient layer 126, as is illustrated in Figure 5.

The sides of the body portions 110 of the pins 108 may be smooth. However, it also falls within the scope of the present invention that the sides of the body portion 110 of the pins 108 may be textured (for example, roughened) to provide improved engagement between adjacent pins.

In a further embodiment of the present invention the bodies 110 of the pins 108 of the pin matrix is provided with screw threads 128 and the heads 114 of the pins are provided with rotational engagement means 130, as illustrated in Figure 6. Such an rotational engagement means 130 may, for example, be a screw or socket head fitting, including but not limited to a slot (flathead), Phillips� (crosshead), Pozidriv� or Hex-key. In order to adjust the position of such a pin 108 with a rotational engagement means 130, the adjustment tool 116 engages with the head 114 and rotates the pin to screw it down through the pin matrix 102 such that the respective tip 112 protrudes beyond the plane of the points of the un-configured pins. To reconfigure the die the adjustment tool 116 re-engages with the rotational engagement means 130 and reverses the adjustment that was made during configuration of the pin matrix.

Pins with sharp or relatively sharp points may for example have tips of substantially conic shape, in the shape of conic frusta, pyramidal, or a wedge-like shape.

Pins may have non-pointed tips (that is, blunt tips). Such pins may be particularly suited to the operation of creasing sheet material. Figures 7A and 7B illustrate examples of such pins 108 having non-pointed tips 132, which are curved 134 or have flat ends 136 respectively. Alternatively such non-pointed tips may be in the shape of conic frusta.

All of the pins of a pin matrix may be of a uniform design, as is the case depicted in the figures. However, a pin matrix may alternatively comprise pins of more than one design. In particular, pins with differently shaped tips may be provided within a single pin matrix to perform different purposes, for example cutting and creasing.

In the devices described previously the pins in the pin matrix are held in contact with the neighbouring pins, and are clamped within a frame. In an alternative design the pin matrix may be sub-divided into a plurality of sub-matrices, which are each clamped within a frame. In a further embodiment the pins may be individually held in a frame, such that they are not in contact with the neighbouring pins, and in the clamped mode each pin is separately clamped into position by a mechanism associated with the frame.

Although the embodiments described above have concerned a flat-bed die, it is envisaged that a curved die may be formed with a pin matrix 802 according to the present invention, as illustrated in Figure 8. In shape, such a curved die may be cylindrical or correspond with part of a cylindrical surface, such that in a pressing operation the die is rolled across a sheet material, in the case that the pins 808 are not individually held within a frame, then tapered sections may be provided between some or all adjacent pins.

The resilient cutting platen 122 may be a fixed block. Alternatively it may comprise a belt of resilient material and a fixed support, such that the fixed support underlies the belt where the die 100 presses against the belt. The belt may be driven between pressings of the die 100, such that the die does not press against an identical portion of the belt in successive pressing operations.

The die of the present invention may be provided with gas control system able to cause a flow of gas (for example, air) through gaps between the pins of the pin matrix, substantially parallel with the axes of the pins, in order to assist in the handling of the sheet material and blank. The gas control system may be located on the same side of the pin matrix as the heads of the pins. By means of inducing a reduced pressure adjacent to the pin heads (that is a negative differential pressure across the pins, by suction) the gas control system may cause a sheet or cut blank to be held against the pin matrix. Conversely, by means of a positive differential pressure the gas control system may cause a sheet or cut blank to be driven from the die.

As well as being suited to cutting and/or creasing of cardboard, a die according to the present invention is also suited to use with other sheet materials, including by not limited to paper and plastics.

Use of a die comprising a pin matrix is within the scope of the present invention.

A method of operating a press with a die comprising of a pin matrix is within the scope of the present invention. The method comprises: configuration of the pin matrix with a pattern corresponding to a cutting andlor creasing pattern; cutting and/or creasing of sheets of material; reconfiguration of the pin matrix into an unconfigured state or into differently configured state.

A method of forming a blank using a die comprising a pin matrix also is within the scope of the present invention. In such a method a press having a configured die comprising a pin matrix is loaded with a sheet of material, the die is pressed against the sheet to form a blank, and sheet is released from the press, and the blank is separated from surrounding waste.

Claims

Claims 1. A die suitable for use in the manufacture of paperboard blanks comprising an array of pins and an adjustable frame within which the pins are contained, wherein the pins each have a longitudinal axis and adjacent pins are substantially parallel and wherein the frame is adjustable between a clamped state in which each pin is fixed relative to the adjacent pins and an unclamped state in which the position of each pin is adjustable along its longitudinal axis relative to the adjacent pins.
2. A die according to claim 1, wherein the pins have a head, a tip and a body, the head and the tip being at opposed ends of the body.
3. A die according to claim 2, wherein, in an unconfigured state the positions of the tips of the array of pins correspond with a plane.
4. A die according to claim 2, wherein, in an unconfigured state the positions of the tips of the array of pins correspond with a curved surface.
5. A die according to one of claims 2, 3 and 4, wherein the tip is one of pointed, rounded, blunt, flat, conic, frusto-conic, pyramidal, and wedge-like shaped.
6. A die according to any preceding claim, wherein the die is configured to produce one of a cut, a crease or both a cut and a crease in operation.
7. A die according to any preceding claim, wherein the heads of the pins are flat.
8. A die according to one of claims 1 to 6, wherein the heads of the pins are dimpled
9. A die according to any preceding claim, wherein the pins are closely packed in an arrangement that is a perpendicular, hexagonally tessellated or triangularly tessellated array.
10. A die according to any preceding claim, wherein the cross-section of each pin, perpendicular to its respective longitudinal axis, is one of circular, square, hexagonal, triangular and star shaped.
II. A die according to one of claims I to 9, wherein the bodies of the pins are provided with splines such that the splines of adjacent pins engage.
12. A die according to any preceding claim, wherein the bodies of the pins are coated with a resilient layer.
13. A die according to one of claims I to 11, wherein the bodies of the pins are provided with a textured surface.
14. A die according to any preceding claim, wherein the pin matrix comprises pins of a substantially identical design.
15. A die according to one of claims I to 13, wherein the pin matrix comprises pins of a plurality of different designs.
16. A die according to any preceding claim, wherein the pin matrix is sub-divided into a plurality of sub-matrices.
17. A die according to any preceding claim, wherein adjacent pins abut.
IS. A die according to one of claims I to 16, wherein the pins are individually held by the frame.
19. A press for cutting andlor scoring comprising a die according to any preceding claim.
20. A press according to claim 19, wherein the press further comprises an adjustment tool.
21. A press according to claim 20, wherein the adjustment tool is capable of adjusting one pin.
22. A press according to claim 20, wherein the adjustment tool is capable of adjusting a plurality of pins.
23. A press according to one of claims 19 to 22, wherein the die is provided with a gas control system capable of inducing a flow of gas through gaps between pins in the pin matrix.
24. A method of configuring a die or a press according to any preceding claim, wherein the positions of pins are adjusted such that selected pins protrude from the remaining pins.
25. A method of configuring a die or a press according to claim 24, wherein the method comprises presenting the pins adjacent to a resilient or deformable material, adjusting the die into an unclamped state, adjusting the positions of selected pins such that they press into or partially penetrate the resilient or deformable material adjusting the die into a clamped state and removing the die from the resilient or deformable material.
26. A method of configuring a die or a press according to claim 25, wherein the positions of pins are adjusted by means of pushing along their respective longitudinal axes.
27. A method of configuring a die or a press according to claim 25, wherein the body of each pin is provided with a screw thread and the head of each pin is provided with rotational engagement means, the positions of the pins are adjusted by means of rotation about their respective longitudinal axes.
28. A method of cutting and/or scoring a sheet comprising configuring a die or a press according one of claims I to 23, and further comprising the operation of pressing the die against a sheet such that pins pierce the sheet and/or further pins deform the sheet.
29. A method according to claim 28, wherein a blank is cut from the sheet, and wherein a further operation separates the portion of the sheet corresponding to the blank from that portion comprising waste that surrounds the blank.
30. A method according to one of claims 28 and 29, wherein the sheet is disposed on a resilient cutting platen during the cutting and/or scoring.
31. A method according to one of claims 28 and 29, wherein the sheet is disposed on a belt of resilient material that is driven between pressing operations such that in successive pressing operations the die is operable upon different portions of the belt.
32. A device substantially as hereinbefore described with reference to and as illustrated in the Figures.