GB2318078A

GB2318078A - A die cutting machine

Info

Publication number: GB2318078A
Application number: GB9621053A
Authority: GB
Inventors: Richard Caswall Rolt
Original assignee: Individual
Current assignee: Individual
Priority date: 1996-10-09
Filing date: 1996-10-09
Publication date: 1998-04-15
Anticipated expiration: 2016-10-09
Also published as: GB9621053D0; GB2318078B

Abstract

A die cutting machine required to process webs of material punches holes or presses shapes from the material (the "workpiece") fed through the machine or cuts layers of material fed through the machine without cutting all the way through the material (in this instance the machine is known as a kiss cutter). The die cutting machine comprises a die for pressing or cutting a workpiece (24) and a support table (8,10) for supporting the workpiece (24), the support table (8,10) being mounted on a cushion of air so as to be movable linearly and rotationally relative to the die. Fine adjustment in the position of the workpiece may be therefore made prior to pressing or cutting.

Description

A Die Cuttine Machine The invention relates to die cutting machinery, particularly but not exclusively to die cutting machines required to process webs of material. A die cutting machine punches holes or presses shapes from material (the work piece") fed through the machine or cuts layers of material fed through the machine without cutting all the way through the material (in this instance the machine is known as a kiss cutter).

A fist aspect of the invention provides a die cutting machine incorporating a support table mounted on a cushion of air so as to allow adjustments in the position thereof.

Preferably, the support table is free to move in three directions.

A second aspect of the invention provides a die cutting machine incorporating a video camera located so as to view a work pieces Preferably, the video camera is mounted rigidly.

Preferably, the video camera is mounted in a top platen.

Preferably, the video camera views the work piece through a hole in a die.

A third aspect of the invention provides a die cutting machine incorporating control circuitry for identifying registration marks on a work piece and adjusting the position of the work piece.

An embodiment of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a perspective view of a die cutting machine according to the invention; Figure 2 is a plan view of the die cutting machine of Figure 1; Figure 3 is a perspective view of the internal construction of the die cutting machine of Figure 1; Figure 4 is a side view of the die cutting machine of Figure 1; Figure 5 is a perspective view of a die of the die cutting machine of Figure 1; Figure 6 is a view of a series of video camera frames; and Figure 7 is a view of a video camera.

The embodiment of the invention shown in Figures 1 to 7 comprises a bottom platen 2 and a top platen 4. The top platen 4 is located directly above the bottom platen 2 and may be moved vertically relative to the bottom platen 2 in the directions indicated by arrow A.

Movement of the top platen 4 is guided by four guide rods 6 and achieved by any suitable means, for example a hydraulic ram and an appropriate control system (not shown). The perspective view of Figure 1 shows only three of the four guide rods 6.

Two support tables 8, 10 are provided. The upper surface 12 of each support table 8, 10 lies in the same plane as the upper surface 14 of the bottom platen 2. The two support tables 8,10 are located on opposite sides of the bottom platen 2 and are mounted on bearings 16, 18 respectively. The bearings 16, 18 allow the support tables 8, 10 to be moved in the plane of the upper surfaces 12, 14. The bearings 16, 18 allow linear movement of the support tables 8, 10 in the directions indicated by arrows X and Y. The bearings 16, 18 also allow angular movement of the support tables 8, 10 in the directions indicated by arrow Theta (see Figure 1). A combination of the movement indicated by the arrows X, Y and Theta allows the position of the support tables 8, ] O to be finely adjustei Arrow B in Figure 2 shows an example of how the position of the support tables 8, 10 may be altered. The bearings 16, 18 are preferably in the form of air cushion bearings. Suilable means, for example electric motors and an appropriate control system (not shown). are provided for moving the support tables 8, 10 in the directions indicated by arrows X, Y and Theta.

Two pull rollers 20, 22 are located on the opposite side of the support table 10 to the bottom platen 2. The pull rollers 20, 22 are arranged so as to be capable of griping and pulling a web of material 24 in the direction indicated by arrow C. Rotation of the pull rollers 20, 22 may be achieved by any suitable means, for example electric motors and an appropriate control system (not shown).

Figure 3 shows a perspective view of the arrangement of equipment within the top platen 4.

Two video cameras 26 are located within the top platen 4 and arranged so as to view the web of material 24 through slots 28 in the lower wall 30. The video carneras 26 are rigidly mounted in the heavy construction of the die press head so that the settling time required in the event of vibration is very short. This allows the apparatus to be operated at high speeds and with a high degree of accuracy. In the case of the illustrated embodiment, in which die 34 is a kiss cutting die, designed to cut only part way through the web of material 24, the slots 28 are covered by a sheet of armoured glass 32 and the dic 34 is located on the lower surface 36 thereof. The die 34 consists of a metal plate 38 incorporating eight cutting members 40 and two holes 42. When the armoured glass 32 and the die 34 are mounted on the top platen 4, the two video cameras 26 view the web of material 24 through the slots 28, the annoured glass 32 and the holes 42. The armoured glass 32 serves lo seal the slots 28 and, by accurate control of its thickness, ensure that the web of material 24 is cut to the required depth. In the case of a standard die set for which the glass 32 is not required, the cameras can look directly through holes provided in the dic.

The apparatus described above collectively comprises an embodiment of a die cutting machine 44 according to the invention.

When in use, the die cutting machine 44 rapidly pulls a web of material 24 over the support tables 8, O and between the platens 2, 4 by operation of thc pull rollers 20. 22. The support tables 8, 10 provide the web of materials 24 with tension and guide the web of material 24 to and from the upper surface 14. The pull rollers 20, 22 continue to pull the web of material 24 between the platen 2, 4 until the video cameras 26 view registration marks 46 which have been previously printed on the web of material 24. When the video cameras 26 view the registration marks 46, control circuitry (not shown) stops the rotation of the pull rollers 20, 22 so that the back edges 48 of the registration marks 46 are in view of the video cameras 26.

The web of material 24 is thereby roughly positioned for fine adjustment by the appropriate movement of the support tables, 8 10. Movemenl of the support tables 8, 10 may be controlled by an operator or automatically and changes the position of the web of material 24 on the upper surface 14. This change in position is monitored by means of the video cameras 26. The exact position of the web for cutting may be achieved by aligning the registration marks 46 with datum lines 50 shown on video screens 52 used by the operator to view the images from the video cameras 26 (see figure 3). Once the web of material 24 is in the correct position, the hydraulic ram is operated. The die 34 is thereby accurately pressed inlo the web of material 24. The top platen 4 is then raised and the pull rollers 20, 22 continue to supply the web of material 24 until further registration marks are detected by the vidco cameras 26 and the associated control circuitry.

Figures 6 and 7 show how the control circuitry slops the pull rollers 20, 22 so that the back edges 48 of the registration marks 46 are in view of the video cameras 26. Each of the video cameras 26 produces a series of frames 54 which, when viewed in rapid succession, may generate a moving picture. Each frame is generated in approximately 40 milliseconds by scanning the field of view 56 of the video camera. A number of scanning lines 58 are produced which are compiled by the video camera to give a frame synch pulse. The video camera then begins the scanning process again. However, whilst the video camera is generating the frame synch pulse, it is effectively blind. The control circuitry calculates the exact position of the registration marks during the scanning phase by analysing previous frames. Each frame is searched for regular marks which could be a registration mark 46.

Once a registration mark 46 is found, the amount Delta by which it moves between successive scanning lines is measured The control circuitry then interpolates to determine the speed of movement of the registration mark and when the registration mark first appeared in the video camera's field of view 56. This information is then processed to stop the back edge of the registration mark in the appropriate position for fine adjustment.

Claims

CLAIMS:

1. A die cutting machine comprising a die for pressing or cutting a work piece and a support table for supporting the work piece, the support table being mounted on a cushion of air so as to be moveable relative to the die.

2. A die cutting machine as claimed in claim 1, wherein the cushion of air is provided by at least one air bearing.

3. A die cutting machine as claimed in claim 1 or 2, wherein the support table is moveable linearly and rotationally in any direction within a plane.

4. A die cutting machine as claimed in any preceding claim, wherein the movement of the support table is driveable with driving means.

5. A die cutting machine as claimed in claim 4, wherein the driving means comprises an electric motor.

6. A die cutting machine as claimed in any preceding claim, wherein the position of the support table relative to the die is lockable.

7. A die cutting machine substantially as hereinbefore described with reference to, and as shown in, the accompanying drawings.

Amendments to the claims have been filed as follows 1. A die cutting machine comprising a die for pressing or cutting a work piece and a support table for supporting the work piece, the support table being mounted on a cushion of air so as to be moveable linearly and rotationally relative to the die.

2. A die cutting machine as claimed in claim 1, wherein the cushion.

of air is provided by at least one air bearing.

3. A die cutting machine as claimed in claim 1 or 2, wherein the support table is moveable in any direction within a plane.