GB2224967A

GB2224967A - "Die-cutting presses"

Info

Publication number: GB2224967A
Application number: GB8918994A
Authority: GB
Inventors: Richard Gardiner
Original assignee: TEAM TOOL Co Ltd
Current assignee: TEAM TOOL Co Ltd
Priority date: 1988-09-07
Filing date: 1989-08-21
Publication date: 1990-05-23
Also published as: GB8918994D0; GB8821041D0

Abstract

A die-cutting press comprises a movable bed 7 for supporting a die for cutting and/or creasing a sheet, a pressing roller 5 for applying pressure to the combination of the die and the sheet supported on the bed 7 to form the required cuts and/or creases in the sheet, drive means for rotating the pressing roller and for moving the bed relative to the pressing roller so that the combination of the die and the sheet is roll pressed between the pressing roller and the bed, and a support roller 6 for supporting the bed during movement of the bed relative to the pressing roller. Preferably, the speed of rotation of each of the rollers 5 and 6 and the speed at which the bed 7 is moved between the rollers e.g. by a rack (17, Fig. 3) are synchronised so that no slip occurs between each roller and the bed. Mechanisms e.g. suction grippers 29 for loading and discharging sheets from the bed may also be provided. <IMAGE>

Description

"Die-Cuttina Presses" This invention relates to die-cutting presses.

It is well known to use a platen die-cutting press for cutting and creasing solid board or corrugated board. There are two general types of platen press.

One is a flat bed press and the other is commonly referred to as a clam shell platen press. The flat bed press is very expensive indeed. The clam shell platen press comprises two hinged plates between which the board and one or more die members are pressed in order to form the required cuts and creases. This latter type of press is also expensive, although not normally as expensive as a flat bed platen press, is very slow and is inherently unsafe.

It is also known to use a rotary press in which a die is provided on a press roller. Again this press is expensive and die changes are also expensive.

It is an object of the invention to provide a generally improved form of die-cutting press.

According to the present invention there is provided a die-cutting press comprising a movable bed for supporting a die for cutting and/or creasing a sheet, a pressing roller for applying pressure to the combination of the die and the sheet supported cn that bed to form the required cuts and/or creases in the sheet, drive means for rotating the pressing rolle and for moving the bed relative to the pressed roller so that the combination of the die and the sheet is roll pressed between the pressing roller and the bed, and a support roller for supporting the bed during movement of the bed relative to the pressing roller.

Preferably, the press also comprises transmission means for transmitting drive from the drive means to the pressing roller and for transmitting drive from the drive means to the bed such that points on the periphery of the pressing roller are caused to move at the same speed or substantially the same speed as the bed during roll pressing.

Usefully, the transmission means is adapted to transmit drive from the drive means to the support roller such that points on the periphery of the support roller are caused to move at the same speed or substantially the same speed as the bed during roll pressing.

Thus, in operation, the speed of rotation of each of the rollers and the speed at which the bed is moved between the rollers are synchronised or very nearly synchronised so that no slip or only an insignificant amount of slip occurs between each roller and the bed supporting the die and the sheet to be cut and/or creased. This does not necessarily imply that the two rollers will be rotated at the same speed as the rollers may be of different diameters.

Such synchronisation has the added advantage that the press can be used for reverse creasing, b; placing complementary die members on opposite sides of the sheet to be creased. The die members must be accurately aligned on opposite sides of the sheet for this purpose, and this requirement can be met in use of such a press if one of the die members is fixed to the bed on one side of the sheet and the complementary die member is fixed to the pressing roller on the opposite side of the sheet.

Preferably, the bed is movable horizontally by the drive means from a loading position on the input side of the pressing roller to a discharge position on the output side of the pressing roller and back to the loading position after removal of the sheet from the bed. In this case, the press advantageously comprises discharge means for removing the sheet from the bed after formation of the required cuts and/or creases. The discharge means may comprise gripping means, e.g. pneumatic suction means, for removing the sheet from the bed and for subsequently releasing the sheet. The gripping means may be vertically movable for raising the sheet from the bed and for subsequently lowering the sheet onto a support below the discharge position of the bed, after the bed has been moved back to the loading position.The support may be vertically movable, such as in response to a signal produced b thc gripping means, and the gripping means may comprise a plurality of grippers, which are mounted on a vertically movable carrier extending above the discharge position of the bed in a direction transverse to the direction of movement of the bed from the loading position to the discharge position and which may be individually upwardly movable relative to the carrier, such as against the urging force of spring means.

Advantageously, the die-cutting press also comprises loading means for loading a sheet onto the bed. The loading means may be similar to the discharge means and if the bed is movable horizontally from a loading position on the input side of the pressing roller to a discharge position on the output side of the pressing roller and back to the loading position, the loading means may be arranged to remove a sheet from a stack of sheets mounted, in use, on a support provided below the loading position of the bed and to subsequently lower the sheet onto the bed. In this case, the support provided below the loading position of the bed may be vertically movable, such as in response to a signal produced by the loading means.

In order that the invention may be more fully understood, a preferred embodiment of die-cutting press in accordance with the invention will now be describe4, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a perspective, diagrammatic view of the press, with parts removed for reasons of clarity; Figures 2 and 3 are diagrams illustratin the operation of the drive system of the press, Figure 4 shows part of a discharge mechanism of the press, Figure 5 shows a suction device for holding a sheet to be cut and/or creased, on a die member, and Figure 6 shows part of a modified press having a hydraulic lifting mechanism for raising the pressing roller.

Referring to Figure 1, the press 1 comprises a frame 2 having legs 3 and a sub fame 4 supporting a hollow steel pressing roller 5 and a hollow steel support roller 6. The frame 2 supports a movable bed 7 for supporting a first die member (not shown) for cutting and/or creasing a solid board sheet placed on the die member.

The pressing roller 5 and the support roller 6 may be of similar or different diameters. As shown diagrammatically in Figure 1, and in Figure 6, the two rollers are of similar diameter, but as shown in Figures 2 and 3, the pressing roller 5 is of larger diameter than the support roller 6. As mentioned later, the rollers 5 and 6 will generally be of similar diameter if the press is only required to provide a partial reverse crease in a solid board sheet. If a full reverse crease is to be provided, a second die member is attached to the pressing roller 5, and in t;1 case, the pressing roller 5 is generally of large diameter than the support roller 6.

The bed 7 is movable horizontally i; tt direction of the arrow 8 from a loading position slightly removed from the position shown in the figure to a discharge position 9 shown in broken lines and back to the loading position. In moving to and fro between the loading position and the discharge position the bed 7 and the first die member pass between the pressing roller 5 and the support roller 6.

The press 1 also comprises two vertically adjustable tables 10 and 11, arranged below the loading position and the discharge position, respectively, a loading mechanism 12 and a discharge mechanism 13. When the bed 7 is in the discharge position 9, the loading mechanism 12 picks up a solid board sheet from a stack of sheets 40 on the table 10 and places this sheet on the first die member when the bed 7 has moved back to the loading position. The bed 7 with the first die member and the sheet is then passed between the pressing roller 5 and the support roller r to the discharge position 9. In this discharge position, the sheet is removed from the first die member by the discharge mechanism 13 and at the same time a fresh sheet is picked up by the loading mechanisir.- 12.When the bed 7 has been drawn back to the loading position, the firstmentioned sheet is placed on the table 11 by the discharge mechanism 13.

Figures 2 and 3 illustrate the arrangece;it b > - which the rollers 5 and 6 and the bed 7 are drlver. Xr, synchronisation. Figure 3 is a view of one eno of C? of the rollers 5 and 6 taken along the line III-III in Figure 2. Referring to Figure 3 the pressing roller 5 is journalled at each end in a top bearing block 14, and the support roller 6 is journalled at each end in a bottom bearing block 15.

The support roller 6 is rotatably driven at the opposite end to that shown in Figure 3 by an electrical motor and suitable gearing (not shown).

Furthermore a respective spur gear 16 is attached to each end of the support roller 6 and drives a respective rack 17 attached to the lower surface of the bed 7 adjacent each lateral edge of the bed 7.

A further spur gear 18 is attached to the one end of the support roller 6 and meshes with an idler spur gear 19, as may be seen more particularly in Figure 2. The idler spur gear 19 is rotatable with a toothed timing belt pulley 20 which rotatably drives the pressing roller 5 by means of a timing belt 21 extending around a toothed timing belt pulley 22 attached to the one end of the pressing roller 5. The pulley 20 has twenty teeth and the pulley 22 has sixty teeth, giving a drive ratio of 1:3. The timing belt 21 is tensioned by a fixed pulley 23 and a tensioning pulley 24 carried by an arm 25 and adjustable in position by an adjusting mechanism 26.

The pressing roller 5 is also capable of being adjusted in height relative to the support roller 6 so as to vary the gap betweer, the rollers 5 : . Inr arrangement for performing this adjustment comprises two screwthreaded adjustment bars 27 (only one shown) each of which engages a respective bearing block 14 of the pressing roller 5. In order to ensure that the rollers 5 and 6 remain parallel during such adjustment, the adjustment bars 27 are interconnected by an endless chain (not shown), and height adjustment is effected by rotating one of the adjustment bars 27 by means of a ratchet handle 28, the other bar member being caused to rotate correspondingly by being driven via the endless chain.

The loading and discharge mechanisms 12 and 13, respectively, are of similar construction and part of the discharge mechanism 13 is shown in Figure 4.

The mechanism 13 comprises gripping means in the form of a plurality of grippers 29 mounted on a vertically movable carrier 30. The carrier 30 extends above the discharge position in a direction transverse to the direction of movement of the bed 7 and is movable vertically by pneumatic actuators 31 (or by a d.c.

servo motor) operated in timed relationship relative to movement of the bed 7, by a process controller (PC) 3 > .

The grippers 29 are in the form of pneumatic suction nozzles which are individually upwardly movable relative to the carrier 3 against the urging force of respectiv springs 33. One of the grippers 29, preferably a gripper located midway or approximately midway betwee: the ends of the carrier 30, operates a limit switc: 3 (see Figure 4) when it moves relative to the carrier 30 by more than a predetermined distance against the urging force of the respective spring 33 and the output from the limit switch is fed to the PC 32.

The tables 10 and 11 each have an upper support surface 34 which is connected to a base 35 by a scissor-linkage 36 and which can be raised and lowered relative to its base 35 by an hydraulic actuator 37 operated by the PC 32.

When the bed 7 in combination with the first die member and a cut and/or creased sheet reaches the discharge position, the discharge carrier 30 is lowered by the actuators 31 to bring at least some of the suction nozzles 29 into contact with the cut and/or creased sheet. The discharge carrier 30 is then raised to remove the cut and/or creased sheet from the first die member. When the bed 7 in combination with the first die member has been drawn back through the rollers 5 and 6 to the loading position, the discharge carrier 30 is again lowered to place the cut and/or creased sheet on the support surface 34 of the table 11 and suction is removed from the nozzles 29. Tne downward travel of the discharge carrier 30 is greater in this latter instance than when removing the sheet from the first die member and if the sheet makes contact with the support surface 34 of the table 11, or with other sheets 41 previously stacked on the table 11, before the carrier 30 reaches an end of travel position, the suction nozzles 29 will move relative to the discharge carrier 30 against the urging force of respective springs 33. If, during the course of the latter movement, the aforesaid limit switch closes, a signal will be fed to the PC 32 which will operate the actuator 37 to lower the table 11. In this way cut and/or creased sheets discharged from the press 1 will be stacked automatically on the table 11.

The loading mechanism 12 operates in similar manner to pick up sheets one at a time from a stack 40 of blank sheets mounted on the table 10 and to place these sheets on the first die member on the bed 7 at the loading position. However, in this case the upper support surface of the table 10 will be raised as sheets are removed from the stack.

As shown in the modified embodiment of Figure 6, an hydraulic lifting mechanism is provided for raising the pressing roller 5 as the bed 7 and the first die member are moved from the discharge position to the loading position. This increases the life of the pressing roller 5 and reduces wear on the blades of the first die member. As shown in Figure 6, the pressing roller 5 is journalled at each end in a top bearing block 14' which is guided for vertical movement along guide bars 45 supported by sub-frame 4'. The lifting mechanism comprises hydraulic rams 46, also supported by the sub-frame 4', for raising and lowering ttie bearing blocks 14'.The rams 46 are connected to a threw position valve 47 which is operated to (a) lower the pressing roller 5, (b) lock the pressing roller 5 in a lowered position whilst the bed 7 is moved from a loading position to a discharge position, and (c) raise the pressing roller 5 prior to return of the bed 7 to the loading position. A pressure switch 48 senses the pressure in the supply lines to the rams 46 and signals the PC 32 when the valve 47 is to be moved to its central position to lock the pressing roller 5 in its lowered position.

A guard (not shown) may be provided to cover the press during operation.

The press described is particularly advantageous in use for forming reverse creases in a solid board sheet. For this purpose a second die member complementary to the first die member mounted on the bed 7 is required to be attached to the pressing roller 5.

To this end the second die member (not illustrated) may comprise a magnetic blanket having a rubber base and incorporating permanently magnetic material, and a series of blocks attached to the magnetic blanket by double-sided adhesive tape. The blocks form complementary formations which cooperate with the formations on the first die member to form the required reverse creases.

In order to attach the second die member to the pressing roller 5 such that the complementary formations on the second die member exactly register with the corresponding formations on the first die member during pressing operation, the second die member is positioned on top of the first die member with the formations on the two die members facing one another and in register and with the bed 7 in its loading position 9. An inching control is then operated to move the bed 7 between the rollers 5 and 6 in discontinuous stepwise manner. As the magnetic blanket is contacted by the outer cylindrical surface of the pressing roller 5, the second die member is magnetically attracted to the roller 5 and is wrapped around the roller 5.The press is ready to receive a solid board sheet to which inverse creasing is to be applied by pressing the sheet between the first die member on which it is supported and the second die member attached to the pressing roller 5.

Alternatively, if a partial reverse crease is satisfactory, then the pressing roller 7 may comprise a hollow steel core and a deformable sleeve of polyurethane which is moulded onto the hollow steel core and which, in use, deforms to allow for the formation of a partial reverse crease as the die and sheet are roll pressed between the bed 7 and the roller 5. In this case, the pressing roller can be much smaller than is shown in Figures 2 and 3 of the drawings and can be of similar size to the support roller.

Conveniently, the bed 7 is made of aluminiur sheet or is in the form of an aluminium: framework structure, and the first die member con*er.icn;,+ comprises a wooden board 52 and one or more steel blades 53 (see Figure 5) inserted in grooves in the board so as to lie proud of the upper surface of the board.

The first die member is held in position on the bed 7 in per se known manner by spring-loaded locating pins which are compressed as the bed 7 passes between the rollers 5 and 6. Suction devices 50 (see Figure 5) may be provided at the leading edge of the first die member to grip a sheet and prevent the sheet from skidding on the first die member. The suction devices 50 are located in slots in the wooden board 52 of the first die member and are connected to a source of vacuum via connectors 51. These suction devices collapse under suction to the same height as the blades 53 so as to hold a sheet against the blades 53.

Furthermore it is preferred that the electrical motor for driving the press is a brake motor having the properties that it is accelerated to its required operating speed in a very short space of time on switch on and that it is correspondingly decelerated very rapidly on switch off.

The die-cutting press described above is inexpensive as compared with known die-cutting presses. It operates at a high speed, aide by automatic loading and discharge arrangements, has a large sheet area, and is conducive to rapid die changes.

Claims

1. A die-cutting press comprising a movable bed for supporting a die for cutting and/or creasing a sheet, a pressing roller for applying pressure to the combination of the die and the sheet supported on the bed to form the required cuts and/or creases in the sheet, drive means for rotating the pressing roller and for moving the bed relative to the pressing roller so that the combination of the die and the sheet is roll pressed between the pressing roller and the bed, and a support roller for supporting the bed during movement of the bed relative to the pressing roller.

2. A die-cutting press as claimed in Claim 1, further comprising transmission means for transmitting drive from the drive means to the pressing roller and for transmitting drive from the drive means to the bed such that points on the periphery of the pressing roller are caused to move at the same speed or substantially the same speed as the bed during roll pressing.

3. A die-cutting press as claimed in Claim 2, wherein the transmission means is adapted to transmit drive from the drive means to the support roller such that points on the periphery of the support roller are caused to move at the same speed or substantially the same speed as the bed during roll pressing.

4. A die-cuttiny press as claimed in any one of the preceding claims, wherein the bed is mcxaLle horizontally by the drive means from a loading position on the input side of the pressing roller to a discharge position on the output side of the pressing roller and back to the loading position after removal of the sheet from the bed.

5. A die-cutting press as claimed in Claim 4, wherein the pressing roller is mounted above the bed and means are provided to raise the pressing roller prior to moving the bed from said discharge position to said loading position.

6. A die-cutting press as claimed in Claim 4 or Claim 5, wherein suction means are provided to hold the leading edge of the sheet relative to the die to prevent slip between the sheet and the die as the combination of the die and the sheet is roll pressed between the pressing roller and the bed.

7. A die-cutting press as claimed in any one of Claims 4 to 6, further comprising discharge means for removing the sheet from the bed after formation of the required cuts and/or creases.

8. A die-cutting press as claimed in Claim 7, wherein the discharge means comprises gripper means for removing the sheet from the bed and for subsequently releasing the sheet.

9. A die-cutting press as claimed in Claim & wherein the gripper means is vertically movable for raising the sheet from the bed and for subsequently lowering the sheet onto a support below the discharge position of the bed, after the bed has moved back to the loading position.

10. A die-cutting press as claimed in Claim 9, wherein the support is vertically movable in response to a signal produced by the gripper means.

11. A die-cutting press as claimed in any one of claims 8 to 10, wherein the gripper means comprises a vertically movable carrier extending above the discharge position of the bed in a direction transverse to the direction of movement of the bed from the loading position to the discharge position, and a plurality of grippers supported by the carrier.

12. A die-cutting press as claimed in Claim 11, wherein the grippers are individually upwardly movable relative to the carrier against the urging force of spring means.

13. A die-cutting press as claimed in Claim 11 or Claim 12, wherein a d.c.servo motor is provided for moving the carrier up/down.

14. A die-cutting press as claimed in any one of Claims 4 to 13, further comprising loading means for loading a sheet onto the bed.

15. A die-cutting press as claimed in Claim 1X, wherein the loading means comprises gripper means for removing a sheet from a stack of sheets mounted, in use, on a support provided below the loading position of the bed and to subsequently lower the sheet onto tne bed.

16. A die-cutting press as claimed in Claims 15, wherein the support provided below the loading position of the bed is vertically movable in response to a signal produced by the loading means.

17. A die-cutting press substantially as hereinbefore described with reference to the accompanying drawings.