GB2249046A

GB2249046A - Shearing machine

Info

Publication number: GB2249046A
Application number: GB9019578A
Authority: GB
Inventors: Derek Evans
Original assignee: SOUTH STAFFS DESIGNS Ltd
Current assignee: SOUTH STAFFS DESIGNS Ltd
Priority date: 1990-09-07
Filing date: 1990-09-07
Publication date: 1992-04-29
Anticipated expiration: 2010-09-07
Also published as: GB2249046B; GB9019578D0

Abstract

A machine for cutting a strip of metal can make cuts at variable angles to the feed direction of the strip. Cutting blades (4, 5) are driven relative to one another for cutting operations by a drive mechanism (6). The cutting blades (4, 5) and associated support members form die sets (2, 3) which are supported on a main support structure (1). The die sets (2, 3) are mounted such that the angle of the cutting blades (4, 5) can be varied in relation to the face direction of the strip without rotation of the main support structure (1). <IMAGE>

Description

Shearing Machine This invention relates to shearing machines for cutting sheet metal material, and more particularly is concerned with providing such a machine which is able to cut sheet material obliquely to the direction of feed, hereinafter called "the feed direction", of the material to the machine.

Sheet metal material is generally supplied in extended lengths or rolls and is cut to required shorter lengths ready for subsequent pressing or other forming processes. Conventionally the material is cut to the shorter lengths by a shearing machine which simply cuts the material square across its width, ie.

at 900 to the feed direction, so that the cut lengths are of a basic rectangular shape. The cutting blades of the shearing machine are fixed at right angles across the machine and can produce only a square cut on the material supplied to the machine. For some uses, such as, for example, the manufacture of vehicle doors and bonnets, rectangular is not the most convenient shape for the material to be cut into and it has been necessary for additional cutting of the material to the desired end shape to be done in a blanking press in readiness for further processing. This need for additional cutting is wasteful of material and adds to the handling and time involved in a manufacturing process.

Shearing machines have been proposed which are capable of cutting sheet material obliquely, and of varying the angle of the cut, to the feed direction.

However those machines have been cumbersome and the angle of cut difficult to control accurately because the greater part of the machine, including the drive mechanism for operating the cutting blades and at least part of the main support structure, have been bodily moved to adjust the angle at which the blades are presented to the material to be cut. The movement has been hydraulically controlled. The movement of so much of the bulk of the machine has resulted in adjustment of the angle of cut being a relatively slow process, and making changes in the angle of cut can appreciably reduce production rates.

It is an aim of the present invention to provide a shearing machine which is adjustable to enable it to cut sheet metal material obliquely, and which can be more readily adjusted for cutting at required angles.

According to the present invention a shearing machine is provided which comprises a main support structure, a cutting blade drive mechanism supported on the support structure, a pair of co-operating cutting blades of which a first one is restrained from movement relative to the support structure during cutting operations and the second cutting blade is operatively connected to the drive mechanism for reciprocating cutting movement relative to the first cutting blade, the cutting blades being supported on the support structure and movable relative thereto to angularly adjusted positions in which the angle is varied at which the blades are presented for use to the feed direction, and drive means mounted on the support structure and operatively connected to the cutting blades to move them to the angularly adjusted positions.

The support structure and drive mechanism are, therefore, not moved when adjustment is made to the angle of the cutting blades relative to the feed direction. The drive effort required to adjust the cutting blades is considerably less than that required to move a substantial part of the whole machine.

Furthermore the accuracy of the adjustment can be more readily controlled, and the adjustment may be made more quickly than has been possible with the known shearing machines described.

In one angularly adjusted position the cutting blades may be presented to cut sheet metal material at right angles to the feed direction and in one or more other positions the blades may be presented obliquely to that one position. Preferably the angular positioning of the blades for use is infinitely adjustable within a pre-determined maximum range of angular movement. In one embodiment of the invention the limits of the angular movement are i 300 from a standard position at right angles to the feed direction.

The cutting blades may be set in a required angular position to make a series of cuts at the same angle on the sheet material fed to the shearing machine, or they may be arranged to be adjusted between cuts so that successive cuts may be at different angles. For example, the blades may be positioned to square cut the material into square or rectangular shapes; they may be set to cut the material obliquely into parallelogram-shaped lengths, or they may be set to cut the material into lengths of trapezium shapes having opposite ends at different angles, of which one may be a right angle.

Appreciable savings in material can be achieved by the facility for adjusting the angle of cut of the sheet material.

Preferably the cutting blades are angularly adjusted by rotational movement about an axis extending centrally of the lengths of the cutting blades and co-axially with the central longitudinal axis of the cutting loads exerted on the blades in cutting operations.

The cutting blades may be supported by carriers which are mounted for angular movement on the support structure and are caused to be moved angularly by the drive means to adjust the angle of the blades. At least one of the blades may have its carrier carried by a spindle or axle rotatably supported by the support structure and connected to the drive means for rotation. Preferably that carrier is supported by the spindle or axle so that the cutting blade it supports is disposed centrally transversely of the rotational axis of the spindle or axle. Both cutting blades may have their carriers carried by co-axial spindles or axles.Drive may be transmitted to the spindles or axles of both cutting blades by drive transmissions connected to them from the drive means, or the drive means may drive the spindle or axle associated with just one of the cutting blades and the carriers of the two blades be interconnected such that the drive is transmitted from the one spindle to the other through the interconnection. Such an interconnection must allow for the relative movement between the carriers required for the cutting operation of the blades.

The cutting blades may be detachable from the carriers to remove them from the machine, or the carriers may be removable with the cutting blades from the machine. Where the carriers are carried by spindles or axles as described they are preferably detachable from the spindles or axles for removal from the machine. The blades may be assembled in die sets which are attached to the carriers. A guide or guides may be provided on the support structure by which the carriers or die sets can be moved from the side of the support structure into and out of their operative locations on the structure.

Preferably the drive means is powered by one or more electric motors. Ideally a pair of the motors, such as Indramat DC motors, operate together so as to compensate one another for any variations in individual outputs and ensure an accurately controlled drive for adjusting the angle of the cutting blades. The motor or motors may be controlled by a computer which may be programmed to provide a pre-set range, and combinations, of angularly adjusted positions of the cutting blades for use. Drive from the motor or motors is preferably taken to the cutting blades through an anti-backlash gearbox so that highly accurate setting of the blades in their angularly adjusted positions can be achieved.

Support for the cutting blades is preferably provided during cutting operations by load bearers firmly anchored to, or forming part of, the support structure which take the loads exerted on the blades during cutting, and transfer the loads to the support structure. The cutting blades move relative to the bearers during their angular adjustment. Preferably the blades are resiliently urged away from their respective bearers when they are not under load so that, in effect, they float on the bearers. They, or their carriers, may float only just out of bearing contact with the bearers so that bearing contact is made in a cutting operation as soon as the blades are under load from the cutting action. As the cutting blades are moved from one angular position to another the bearing contact with the bearers is relieved.

Consequently there is little or no friction at the bearers to resist the angular adjusting movement of the cutting blades. For their angular movement support is preferably arranged to be provided for the cutting blades by bearings which ease the movement. In any adjusted position of the blades, however, the bearings are preferably arranged to be relieved of loads from the cutting operations by the support afforded the blades by the bearers during these operations.

By virtue of the floating arrangement of the cutting blades on the bearers and the low friction support provided by the bearings during the angular adjustment of the blades, the power required to move the blades angularly may be kept low, and accurate control of the movement of the blades is facilitated.

Additionally, it is possible for the blades to be moved very quickly from one adjusted angular position to another. In a preferred embodiment of a shearing machine in accordance with the present invention the cutting blades can be accelerated to up to 10 metres/ sec2 in their movement between adjusted positions.

Angular adjustment of the blades may be arranged to be made whilst the driving mechanism is operatively connected to the second cutting blade, and without interruption of the feed of sheet material to the machine to be cut. The driving mechanism and feed means for feeding sheet material to the cutting blades may be under computerised control which conveniently also controls the drive means for angularly adjusting the blades. Thus the rate of feed of the sheet material, the lengths into which the material is to be cut and the angle or angles at which the material is cut by the cutting blades can all be programmed into the computerised control and varied as necessary.

The cutting blades may be straight, or they may be curved, angled or otherwise shaped along their lengths to produce shaped ends on the cut sheet material.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which Figure 1 is a partly sectioned front view of a shearing machine in accordance with the invention, and Figure 2 and 3 are a simplified vertical section and partly sectioned plan view respectively of the machine.

In this embodiment the shearing machine comprises a main support structure 1, top and bottom die sets 2 and 3 respectively including top and bottom cutting blades 4 and 5 respectively, a drive mechanism 6 by which relative movement is provided between the cutting blades 4, 5 for cutting operations, and a turning drive 7 by which the cutting blades are movable to angularly adjusted positions at which the blades are presented for use at different angles to the feed direction of the sheet metal material supplied to the machine when in use.

The support structure 1 has a base 8 with anchorage locations 9 spaced around its periphery at which the structure is fixed on a supporting surface in the required position of use of the machine. Rigid with and upstanding from the base 8 are spaced, parallel side cheeks 10, 11 which are reinforced at their lower ends by braces 12 on the base and support a fixed horizontal top spindle holder 13 at their upper ends. A bottom spindle holder 14 extends horizontally between the side cheeks 10, 11 below and parallel to the top spindle holder 13, and is reciprically moved vertically by the drive mechanism 6. Adjustable cam followers 15 at opposite sides of the bottom spindle holder 14 guide the holder in its reciprocating movement. Mounted flat on top of the bottom spindle holder 14 is a table 16 of bow-tie shape in plan, Figure 3, extending longitudinally between the side cheeks 10, 11.

The drive mechanism 6 is of a known form comprising a crank-shaft 17 extending between, and journalled in bearings 18 in, the side cheeks below the bottom spindle holder 14 driven by a DC electric motor 19 through a gearbox 20, both being mounted on a side extension 8' of the base 8 at the outer side of one side cheek 10. Connecting rods 21 on cranks 22 of the crank-shaft 17 are connected to the bottom spindle holder 14 at gudgeons 23 secured between pairs of coupling flanges 24 depending from the underside of the bottom spindle holder 14 adjacent to its opposite ends.

Centrally mounted vertically in tubular housings 26, 27 respectively fixed in the top and bottom spindle holders 13, 14 are co-axial top and bottom spindles 28 and 29 respectively, Figure 2. The bottom spindle and its housing 27 move with the bottom spindle holder 14. The spindles 28, 29 are rotatably supported in their housings 26, 27 by sets of thrust bearings 30 and roller bearings 31. The spindles are normally urged axially, resiliently, towards one another by compression springs 32 arranged around each of the spindles. Each spindle 28, 29 has a series of the compression springs 32 spaced around its circumference which bear on a race of the thrust bearings 30, retained against an annular shoulder 33 in the respective housing 26, 27 and are located in a packing ring 34 abutting against an annular shoulder 35 on the spindle.The adjacent ends of the top and bottom spindles 28, 29 protrude respectively below a bottom bearer plate 36 of the top spindle holder 13 and above the table 16 of the bottom spindle holder 14. An attachment collar 37 is fixed to each of the spindles at a position on the spindle such that under the normal axial urging of the spindle by the springs 32 a front face 38 of the attachment collar 37, towards the other spindle, is level with the underface of the bearer plate 36 in the case of the collar on the top spindle, and level with the top surface of the table 16 as regards the collar on the bottom spindle.

Top and bottom elongated box-section, carriers 39, 40 are detachably secured, by fixing bolts, not shown, to the attachment collars 37 of the top and bottom spindles respectively. Each of these carriers 39, 40 is attached centrally of its length to the attachment collar at a hub 39, 40. While the spindles are being urged towards one another by the compression springs 32 the hubs 39, 40 lift the carriers out of contact with the bearer plate 36 and the table 16. When axial loads are exerted on the spindles, as in cutting operations, which are in opposition to and overcome the force of the springs 32, so that the spindles are moved axially against the spring force, the carriers bottom on and bear on the bearer plate 36 and table 16 respectively. The loads are then borne by the top and bottom spindle holders and transferred to the support structure.

The two carriers 39, 40 are interconnected by posts 41 at their opposite ends which are fixed to the top carrier and slide vertically in guide sleeves 42 fixed to the bottom carrier. The bottom carrier is thus free to move vertically, reciprocally, with the bottom spindle holder relative to the top carrier, but the carriers are tied for movement together in other respects.

The top and bottom die sets 2, 3 each comprise a blade holder 43, 44 to which the top or bottom cutting blade 4, 5, as the case may be, is fixed. The top die set 2 is releasably secured at its blade holder 43, Figure 2, by fixing bolts, not shown, to the top carrier 39 and the bottom die set 3 is releasably secured at its blade holder 44 by fixing screws, not shown, to the bottom carrier 40. A screw adjustment 45 is provided at the bottom carrier for adjusting the associated blade holder 44 laterally on that carrier to set the bottom cutting blade for co-operation with the top cutting blade. Feed guides 46 are also included in the top die set 2 opposite the top cutting blade for guiding sheet metal into position between the blades for cutting when the machine is in use.

The turning drive 7 is above the top spindle holder 13 and drives the top spindle 28 from its upper end to rotate that spindle in its housing 26. The turning drive comprises two DC electric motors 48 which operate together in a self-compensating manner. Drive is transmitted from the motors to the top spindle through drive gears, not shown, by way of an anti-backlash gearbox 49. The gearbox 49 and drive gears are contained within a housing 50 mounted on and supported by the top spindle. The motors 48 are also mounted on that housing 50. Oppositely extending anti-rotation bars 51 fixed to the housing 50 are adjustably connected by turn-buckled tie rods 52 to anchorages 53 fixed on the top spindle holder to restrain the housing and motors from turning about the axis of the spindle.

Rotation of the top spindle by the turning drive causes the top carrier 39 and, through the interconnecting posts 41, the bottom carrier 40 to turn together about the rotational axis of the spindles relative to the top and bottom spindle holders, thereby varying the angular positions at which the cutting blades are presented to the feed direction of sheet material fed into the machine to be cut. The turning is done when the spindles are under the axial loading of the compression springs 32 urging them axially towards one another so that the carriers 39, 40 are out of contact with (in effect floating over) the bearer plate 36 and the table 16. There is, therefore, no frictional resistance to the turning movement from the bearer plate and table. The spindles are supported for free rotation by their thrust bearings 30 and roller bearings 31.Accordingly, a relatively low power output is required from the motors 48 to adjust the angle of the cutting blades. Limit switches 54 on the underside of the bearer plate 36 are operatively connected to the motors and are engageable by the top carrier to cut off the power to the motor to set the limits of the turning movement of the carrier, and hence the angular adjustment of the cutting blades.

Typically the turning movement is limited to f 300 from a standard position of the cutting blades at which they are presented at right angles to the feed direction of sheet material into the machine.

The turning drive is computer controlled to provide selective adjustment of the angle of the cutting blades and the speed at which the cutting blades are moved between desired angular positions for use.

Similarly the drive to the crank-shaft 17 from the electric motors 19 is also computer controlled to control the rotational speed of the crank-shaft and the cutting rate of the cutting blades. The rate at which sheet material is fed to the machine to be cut is also preferably computer controlled and variable as required. The angular adjustment of the blades, the cutting rate of the blades and the feed of the material to be cut can all be programmed at a central control to be automatically related and controlled as desired according to the work for which the sheet material is intended.

The angular adjustment of the cutting blades may be done when the crank-shaft is stationary, or between cutting strokes of the connecting rods whilst the crank-shaft is turning. Adjustment may, therefore, be effected without interruption of the feed of material to the machine.

When the cutting blades are in a cutting operation there is some lost motion when the blades initially make contact with the material to be cut. That lost motion lasts only until the axial force of the compression springs on the spindles is overcome by the opposing applied axial load on the spindles from the operative stroke of the connecting rods moving the bottom spindle holder and its spindle towards the fixed top spindle holder and the top spindle. The cutting action of the blades proceeds when the applied load urges the carriers 39, 40 to bottom on and bear on the bearer plate and table. During the cutting action the applied loads are borne by the top and bottom spindle holders, and hence the support structure, thereby relieving the thrust and roller bearings of the load.

The compression springs resume their action on the spindles to urge the carriers out of contact with the bearer plate and table as soon as the material has been cut and the bottom cutting blade is retracting from the top cutting blade.

A shearing machine in accordance with the embodiment described has been prepared which will cut sheet metal material of 0.4 - 2.00mm at a rate of up to 120 cuts/minute and will take coil fed material up to 2 metres wide. The cutting cycle of the machine is completed within only 900 rotation of the crank-shaft so that 2700 of rotation is available for feed of the material to be cut, enabling a high speed performance to be achieved from a relatively low crank-shaft rotational speed. The material may be fed from the roll at line speeds of up to 150 metres/minute and be cut into lengths of 400 - 3000mm long. Adjustments of the angles of the cutting blades can be made very quickly with rotational acceleration of the spindles by the turning drive of up to 10 metres/sec2.

A guide track 55, Figure 1, is supported by one of the side cheeks 10, by way of which the carriers, still interconnected together but disconnected from the attachment collars 37 of the spindles, can be moved into and out of the support structure for replacement or servicing of the cutting blades.

If desired, a stacker may be provided in conjunction with the shearing machine to receive the cut lengths of material and stack them for subsequent pallet handling. Where lengths are cut with differently angled ends the stacker may be arranged to stack the cut lengths selectively according to their end shapes.

Claims

1. A shearing machine comprising a main support structure, a cutting blade drive mechanism mounted on the support structure, first and second co-operating cutting blades the first cutting blade being restrained from movement relative to the support structure during cutting operations and the second cutting blade being operatively connected to the drive mechanism for reciprocating cutting movement relative to the first cutting blade, the first and second cutting blades being supported on the support structure and movable relative thereto to angularly adjusted positions in which the angle at which the blades are presented to the feed direction for use is varied, and drive means mounted on the support structure and operatively connected to the first and second cutting blades to move them to the angularly adjusted positions.

2. A shearing machine according to claim 1 in which in one of the angularly adjusted positions the cutting blades are presented to cut sheet metal at right-angles to the feed direction.

3. A shearing machine according to claim 1 or claim 2 in which the angle at which the blades are presented to the feed direction is infinitely adjustable within predetermined maximum limits of adjustment.

4. A shearing machine according to any preceding claim in which the cutting blades are angularly adjusted by rotational movement about an axis extending centrally of the cutting blade and coaxially with the central longitudinal axis of the cutting loads exerted on the blades during cutting operations.

5. A shearing machine according to any preceding claim in which each of the cutting blades is mounted on a respective carrier, each carrier being mounted on the support structure for angular movement.

6. A shearing machine according to claim 5 in which at least one of the carriers is mounted on a spindle and the cutting blade supported by that carrier is disposed centrally transversely of the rotational axis of the spindle.

7. A shearing machine according to claim 6 in which both of the carriers are mounted on a respective spindle, the spindles being coaxial.

8. A shearing machine according to claim 7 in which drive is transmitted from the drive means to both spindles.

9. A shearing machine according to claim 7 in which drive is transmitted from the drive means to just one of the spindles, the carriers being interconnected such that drive is transmitted from the said one of the spindles to the other spindle through the interconnection.

10. A shearing machine according to any one of claims 5 to 9 in which the blades are detachable from the carriers for removal from the shearing machine.

11. A shearing machine according to any one of claims 5 to 10 in which the carriers are removable from the machine together with the blades.

12. A shearing machine according to any one of claims 6 to 11 in which the carriers are detachable from the spindle for removal from the machine.

13. A shearing machine according to any preceding claim in which the drive means comprises a direct current electric motor.

14. A shearing machine according to claim 13 having a pair of electric motors which operate together to compensate one another for variations in individual outputs.

15. A shearing machine according to claim 13 or claim 14 in which drive from the or each motor is transmitted to the cutting blades through an anti-backlash gearbox.

16. A shearing machine according to any preceding claim in which bearers are provided, fast with or integral with the support structure to take the loads exerted on the blades during cutting and transfer the loads to the support structure, the blades moving relative to the bearers during their angular adjustment.

17. A shearing machine according to claim 16 in which the blades or the carriers are resiliently biased away from the bearers when they are not under load.

18. A shearing machine according to claim 17 in which bearings are provided to support the blades during angular repositioning of the blades.

19. A shearing machine according to any preceding claim in which the maximum acceleration of the blades during angular repositioning is 10 ms 2.

20. A shearing machine according to any preceding claim in which the blades are angularly adjustable during use of the machine without interruption of the feed of metal to be cut by the blades.

21. A shearing machine according to any preceding claim in which the blades are shaped along their lengths to produce shaped ends on the cut material.

22. A shearing machine substantially as described with reference to the accompanying drawings.