WO1988001556A1

WO1988001556A1 - Cutting means

Info

Publication number: WO1988001556A1
Application number: PCT/AU1987/000288
Authority: WO
Inventors: Christopher Probert
Original assignee: Fortron Automotive Treatments Pty. Ltd.
Priority date: 1986-08-27
Filing date: 1987-08-26
Publication date: 1988-03-10
Also published as: ZA876340B

Abstract

A means of cutting sheet material comprising a cutting table (11) for supporting sheet material, a cutting head (17) mounted to a support (16) to be movable over the table (11), the cutting head (17) supporting an upright shaft (19) which is freely pivotal on the cutting head (17), the shaft (19) supporting a blade (23) to one side of the main axis of the shaft (19) about its upright axis, biassing means (20) for biassing the blade (23) into engagement with the surface of the table (11), the blade (23) having a cutting edge (25) directed in the direction of the shaft which terminates in a sharp blade tip (24), a drive means for causing controlled movement of the cutting head over the table and a control means for causing the controlled movement of the cutting head according to a predetermined pattern to cut pieces of sheet material into shapes.

Description

"CUTTING MEANS"

THIS INVENTION relates to a means of cutting sheet material into predetermined shapes.

In one form the invention resides in a means of cutting sheet material comprising a cutting table for supporting said sheet material, a cutting head mounted to a support to be movable over said table, said cutting head supporting an upright shaft which is freely pivotal on the cutting head, said shaft supporting a blade to one side of the main axis of the shaft about its upright axis biassing means for biassing the blade into engagement with the surface of the table, said blade having a cutting edge directed in the direction of the shaft which terminates in a sharp blade tip a drive means for causing controlled movement of the cutting head over the table and a control means for causing the controlled movement of the cutting head according to a predetermined pattern to cut pieces of sheet material into shapes.

According to a preferred feature of the invention said control means produces a movement of the shaft such that the blade tip moves along the desired cutting path.

According to a preferred feature of the invention said control means causes the blade tip to change its direction of travel between a first and second direction by moving the shaft in a first direction of travel for the distance beyond the change in direction of travel, said distance corresponding to the radius of the rotation path of the blade tip about the central axis of the shaft, rotating the shaft about the blade tip until the shaft overlies the second direction of travel and moving the shaft in the second direction of travel. According to a preferred feature of the previous feature where the change in direction between the first and second direction is via a curve wherein said control means causes the shaft when spaced said distance from the junction between the first direction of travel and the curve to rotate about the centre of curvature of said curve until the shaft axis overlies the second direction of travel and then causing movement of the shaft in the second direction of travel.

According to a further preferred feature of the invention said cutting table is provided with aa upper surface which is capable of being penetrated by the blade tip.

According to a further preferred feature of the invention said cutting table is provide with means for maintaining the sheet material in close intimate contact with the cutting table.

According to a preferred feature of the previous feature the means comprises a plurality of spaced apertures opening into the upper face of the cutting table and connected to an air extraction means.

According to a preferred feature of the invention the cutting head is mounted to a carried rail which extends across the cutting table and said cutting head is movable along the rail, wherein said rail is mounted to the cutting table to be movable over the table along an axis transverse to the rail the movement of the cutting head on the rail and the movement of the rail over the cutting table comprising said controlled movement.

The invention will be more fully understood in the light of the following description of one specific embodiment. The description is made with reference to the accompanying drawings of which:

Figure 1 is a schematic side elevation of the cutting head according to the embodiment;

Figure 2 is a schematic side elevation of the cutting head according to the embodiment;

Figure 3 is a schematic plan view of the cutting head of figure 1;

Figure 4 illustrates the movement of the shaft and blade tip during an instantaneous change in direction;

Figure 5 illustrates the movement of the blade tip and shaft during a gradual change in direction; and

Figures 6 and 7 schematically illustrate one means of effecting controlled movement of the cutting head; and

Figure 8 is an isometric view of an alternative mounting for the cutter blade.

The embodiment is directed to a device for cutting thin film into predetermined shapes. The embodiment comprises a cutting table 11 having a base 12 overlaid by a sheet of material 13 which presents a hard support surface to the sheet material 14 which is to be cut but which can be readily penetrated by a cutting blade without damage to the cutting blade. The table 11 is formed with an array of apertures 15 which open into a plenum space (not shown) beneath the table which is in turn connected to a vacuum source (not shown). The sheet material 14 is stored on rolls 25 mounted transversely on a support stand 26 at one end of the table.

The table 11 is associated with a transverse support rail 16 which is mounted to each side of the table 11 for movement along the length of the table by a first drive means (not shown). The support 16 supports a cutting head 17 which is movable along the support 16 by a second drive means (not shown). The first and second drive means may comprise a drive motor directly driving a roller or the support rail or cutting head respectively or causing movement of the support rail and cutting head through a pulley and cable system as shown at figures 6 and 7.

As shown at figure 5 the cutting head 17 (shown schematically) is movable on the support rail 16 through the action of a first stopper drive motor 30 having a capstan 31. A cable 32 is wrapped around the capstan from the capstan the cable passes around a first roller pulley 33 provided on the support rail to the cutting head 17 where it is attached to a bollard 34 therein. The other end of the cable extends the full length of the cutting table and returns to the support rail after passing over an adjustable caller 35. It then goes around the end guide rollers 36 and 37 at the other end the support rail and return to the cutting head to be fixed to the bollard 34.

As shown at figure 7 the support rail 16 is movable on the table through a second stopper drive motor 40 which also has a capstan 41 to which the cable 42 is attached. One end of the cable extends the length of the table where it passes around a roller pulley 43 and returns to form a rectangular loop around idler rollers 44, 45, 46 and 47 at each corner of the table to be attached to the side of the support: rail remote from the drive motor. The cable is also fixed to the side of the support rail closest to the drive motor in the portion between the drive motor and idler pulley 43. The cutting head is supported on the support 16 for movement therealong by a set of rollers 13. The cutting head also supports an upright shaft 19 at one side thereof. The shaft is rotatabiy supported by the cutting head and is also slidably supported in the cutting head 17. The shaft is biased to its lowermost position in the cutting head 17 via a coil spring 20 which is received over the shaft is mounted between the body of the cutting head and a stop 27 provided on the shaft. The upper end of the shaft 19 is associated with a cam shaped toggle 21 which on rotation can be used to raise the shaft 19 in the cutting head 17 and retain it in the raised position. The lower end of the shaft 19 supports a radial arm 22 which supports a cutting blade 23 at its outer end wherein the cutting blade 23 is formed with a sharp tip 24 at the lower end of its cutting edge 25. The movement of the cutting head 27 is effected through operation of the first and second drive means which are able to move the cutting head along the "X" and "Y" axes defined by the movement of the cutting head 27 on the support rail and the support rail 16 over the cutting table 11. The operation of the first and second drive means is effected through a control means which causes the cutting head to move along a predetermined path whereby the cutting blade 23 cuts the sheet material 14 into predetermined shapes.

The pivotably mounting of the shaft in the cutting head ensures that the tip 24 of the cutting blade 23 trails behind the shaft 19 on movement of the cutting head to facilitate the most efficient cutting action of the sheet material by the cutting blade. This action however, requires that the shaft be moved through the path differing from that which is to be travelled by the tip of the cutting blade 23 due to the trailing action of the cutting blade. The difference in the pattern of movement of the shaft 19 and that of the blade tip 24 arises when a change in direction is executed.

As shown at figure 3 where the blade tip is required to execute an instantaneous change in direction as formed by the intersection of two straight lines comprising a first direction A to B and a second direction B to C, the control means causes cutting head to move to carry in the first direction beyond the point of intersection B between the first and second direction for a distance to a point P, where the length BP equals the radius of the rotation path of the blade tip 24 about the central vertical axis of the shaft 19, The cutting head is then moved whereby the shaft is then caused to rotate about the blade tip which will be located at point B until the shaft overlies the second direction of travel at point Q, at which time the shaft is caused to move in the second direction.

Where the blade tip is caused to execute a gradual change in direction via a curve BC between a first direction of travel AB and a second direction of travel CD the control means again causes cutting head to move to carry the shaft beyond the point B which constitutes the intersection between the first direction AB and the curve BC to a point P which is spaced from the point B a distance corresponding to the radius of the rotation path of the blade tip 24 about the central axis of the shaft 19. The control means then causes the shaft to rotate about the same centre of curvature R as that of the curve 3C until the shaft overlies the second direction of travel CD at point. Q at which time the shaft is caused to move tin the second direction of travel.

As a result of the embodiment a cutting means is provided which ensures the most efficient cutting action of a cutting blade through the utilisation of a trailing arm action and controlled movement of the shaft along a path which compensates for the trailing action of the cutting blade.

Figure 8 illustrates an alternative mounting for the cutting blade 23 which comprises a circular base 50 mounted to the lower end of the shaft 19 such that their control axes are coincidental. The blade 23 is supported on a cut away portion of the base which has a radial face 51 to which the blade 23 is fixed. The fixing of the blade 23 is effected by a clamping plate 52 and a screw which fixes the clamping plate to the bass 50. Suitable locating means are provided on the radiai face to ensure proper positioning of the blade.

The utilisation of the tracking blade eliminates the need for a steering mechanism for the blade in addition to the shaft which also reduces the mass of the cutting head. As a result a neat uniform cut can be produced at a high speed.

It should be appreciated that the scope of the present invention need not be limited to the particular scope of the embodiment described above.

Claims

THE CLAIMS defining the invention are as follows:-

1. A means of cutting sheet material comprising a cutting table for supporting said sheet material, a cutting head mounted to a support to be movable over said table, said cutting head supporting an upright shaft which is freely pivotal on the cutting head, said shaft supporting a blade to one side of the main axis of the shaft about its upright axis biassing means for biassing the blade into engagement with the surface of the table, said blade having a cutting edge directed in the direction of the shaft which terminates in a sharp blade tip a drive means for causing controlled movement of the cutting head over the table and a control means for causing the controlled movement of the cutting head according to a predetermined pattern to cut pieces of sheet material into shapes.

2. A means of cutting sheet material as claimed at claim 1 wherein control means produces a movement of the shaft such that the blade tip moves along the desired cutting path.

3. A means of cutting cutting sheet material as at claim 1 or 2 wherein control means causes the blade tip to change its direction of travel between a first and second direction by moving the shaft in a first direction of travel for the distance beyond the change in direction of travel, said distance corresponding to the radius of the rotation path of the blade tip about the central axis of the shaft, rotating the shaft about the blade tip until the shaft overlies the second direction of travel and moving the shaft in the second direction of travel.

A means of cutting sheet material as claimed at claim 3 wherein the change in direction between the first and second direction is via a curve wherein said control means causes the shaft when spaced said distance from the junction between the first direction of travel and the curve to rotate about the centre of curvature of said curve until the shaft axis overlies the second direction of travel and then causing movement of the shaft in the second direction of travel.

5. A means of cutting sheet material as claimed at any one of the preceding claims wherein said cutting table is provided with an upper surface which is capable of being penetrated by the blade tip.

6. A means of cutting sheet material as claimed at any one of the preceding claims wherein said cutting table is provide with means for maintaining the sheet material in close intimate contact with the cutting table.

7. A means of cutting sheet material as claimed at claim 6 wherein the means comprises a plurality of spaced apertures opening into the upper face of the cutting table and connected to an air extraction means.

8. A means of cutting sheet material as claimed at any one of the preceding claims wherein the cutting head is mounted to a carried rail which extends across the cutting table and said cutting head is movable along the rail, wherein said rail is mounted to the cutting table to be movable over the table along an axis transverse to the rail the movement of the cutting head on the rail and the movement of the rail over the cutting table comprising said controlled movement.

9. A means of cutting sheet material wherein the sheet material comprises the film material.

10. A means of cutting sheet material substantially as herein described.