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Patent Searching and Data


Title:
ROLL FORMING LINE WITH PUNCHING TOOL
Document Type and Number:
WIPO Patent Application WO/2000/023209
Kind Code:
A1
Abstract:
A roll forming line comprising at least one punch unit wherein said at least one punch unit comprises a punch having a punch head and a fluid operated actuating means having an output element operable to move the punch head to punch a workpiece, the punch unit having at least one of the following expedients: a) means to adjust the punch transversely of said line; b) cushioning means to cushion operation of said actuating means.

Inventors:
Cant, Stephen Alfred (72 Celandine Close, Kingsmeadow Kingswinford West Midlands DY6 9TN, GB)
Application Number:
PCT/GB1998/003126
Publication Date:
April 27, 2000
Filing Date:
October 21, 1998
Export Citation:
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Assignee:
THE BRONX ENGINEERING COMPANY LIMITED (Lye Stourbridge West Midlands DY9 8DS, GB)
Cant, Stephen Alfred (72 Celandine Close, Kingsmeadow Kingswinford West Midlands DY6 9TN, GB)
International Classes:
B21D5/08; B21D28/00; B21D28/26; (IPC1-7): B21D5/08; B21D28/00
Foreign References:
US3888099A1975-06-10
US3990240A1976-11-09
US5042362A1991-08-27
Attorney, Agent or Firm:
FORRESTER KETLEY & CO. (Chamberlain House Paradise Place Birmingham B3 3HP, GB)
Download PDF:
Claims:
CLAIMS
1. A roll forming line comprising at least one punch unit wherein said at least one punch unit comprises a punch having a punch head and a fluid operated actuating means having an output element operable to move the punch head to punch a workpiece, the punch unit having at least one of the following expedients: a) means to adjust the punch transversely of said line, b) cushioning means to cushion operation of said actuating means.
2. A roll forming line according to claim I wherein electronic control means are provided to control movement of said output element.
3. A roll forming line according to claim I or claim 2 wherein the punch head is slidable relative to a body by said actuating means.
4. A roll forming line according to claim 3 wherein the actuating means is carried by the punch unit and the body is movable transversely of the line relative to said punch unit.
5. A roll forming line according to claim 3 or claim 4 wherein the body comprises an upper limb in which said punch head is slidable and a lower limb in which is provided an element which cooperates with the punch head to punch the workpiece, the upper and lower limbs being spaced apait by a gap to receive the workpiece.
6. A roll forming line according to claim 5 wherein two bodies are provided disposed side by side to receive opposite sides of the workpiece in the respective gap.
7. A roll forming line according to any one of claims 3 to 6 wherein the or each body is movable relative to the punch unit by the adjustment means in a direction transversely of said line.
8. A roll forming line according to any one of the preceding claims wherein the adjustment means comprises an electric motor.
9. A roll forming line according to any one of claims 1 to 7 wherein the adjustment means comprises a fluid operated ram.
10. A roll forming line according to claim 11 wherein the fluid is a gas such as air or a liquid such as oil.
11. A roll forming line according to any one of the preceding claims wherein sensing means are provided to sense the position of the or each punch head transversely of the line.
12. A roll forming line according to claim 11 where dependent on claim 8 wherein the sensing means comprises an electric motor provided with an encoder.
13. A roll forming line according to claim 11 wherein the adjustment means the sensing means comprises a position transducer to sense the position of the or each punch head.
14. A roll forming line according to claim 13 wherein the position transducer senses the position of the body and thereby sense the position of the or each punch head.
15. A roll forming line according to claim 13 or claim 14 wherein the position transducer comprises a linear transducer or a potentiometer.
16. A roll forming line according to any one of claims 11 to 15 wherein the adjustment means and the sensing means are connected in a closed loop arrangement so that the or each punch may be positioned in a desired position transversely of the line.
17. A roll forming line according to any one of claims l l to 16 wherein the sensing means provides a signal to an electronic control unit in dependence on the position of the or each punch head.
18. A roll forming line according to claim 17 wherein the electronic control unit is programme to move the each body during passage of a workpiece through the punch machine in order to permit the or each punch head to operate on the workpiece at least at two different lateral positions.
19. A roll forcing line according to claim 18 wherein said different lateral positions are at different longitudinal positions along the line.
20. A roll forming line according to any one of claims 1 to 19 wherein the fluid operated actuating means comprises a piston movable in a cylinder under fluid pressure and the cushioning means cushions movement of the piston towards the punching end of its stroke.
21. A roll forming line according to claim 20 wherein said actuating means comprises a position sensor to provide a signal dependent upon the cylinder attaining a position adjacent to the end of its travel in the cylinder in the punching direction to operate said cushioning means.
22. A roll forming line according to claim 20 or claim 21 wherein the piston is movable in the cylinder in a punching direction by application of a pressure differential applied to the piston by the fluid in the cylinder.
23. A roll forming line according to claim 22 wherein the pressure differential is applied to the piston by supply of fluid under pressure to the side of the piston remote from the punching end of the stroke and supply of fluid under the same pressure to the opposite side of the piston, the area of the piston on said one side being greater tlian the area of the piston on the other side.
24. A roll forming line according to claim 23 wherein movement of the piston in the return direction may be as a result of connection of said side of the piston to reservoir whilst said other side of the piston remains connected to fluid under pressure.
25. A roll forming line according to any one of claims 22 to 24 where dependent directly or indirectty on claim 21 wherein the cushioning means comprises a valve operable in dependence on said signal to reduce the pressure differential applied by the fluid to the piston in the direction to cause said movement towards the punching end of the piston stroke.
26. A roll forming line according to claim 25 wherein the valve is operable to interrupt the supply of fluid to the side of the piston remote from the punching end of its stroke and connect the other side of the piston being connected to fluid under pressure.
27. A roll forming line according to claim 25 or claim 26 where dependent directly or indirectly on claim 24 wherein the valve is provided in the fluid path to the cylinder and in a first position to direct the fluid during the punching operation and movable to a second position to direct the fluid during said return operation.
28. A roll forming line according to any one of the preceding claims comprising a plurality of roll passes to bend the workpiece into a desired shape.
29. A roll forming line substantially as hereinbefore described with reference to the accompanying drawings.
30. Any novel feature or novel combination of features described herein and/or in the accompanying drawings.
Description:
ROLL FORMING LINE WITH PUNCHING TOOL Description of Invention This invention relates to a roll forming line.

A conventional line for producing roll formed-metal products has at least one of a punching machine, comprising at least one punching unit, and a roll forming machine, comprising a plurality of roll forming passes. It is desirable that the punching machine is adaptable in order to reduce the productive time spent in changing the configuration of the punching machine.

Hitherto such adaptation of the punching machine has been time consuming.

An aim of the invention is to provide a new or improved roll forming line whereby the above mentioned problem is overcome or is reduced.

According to the invention we provide a roll forming line comprising at least one punch unit wherein said at least one punch unit comprises a punch having a punch head and a fluid operated actuating means having an output element operable to move the punch head to punch a workpiece, the punch unit having at least one of the following expedients: a) adjustment means to adjust the punch transversely of said line, b) cushioning means to cushion operation of said actuating means.

Electronic control means may be provided to control movement of said output element.

The punch head may be slidable relative to a body by said actuating means.

The actuating means may be carried by a punch unit and the body may be movable transversely of the line relative to said punch unit.

The body may comprise an upper limb in which said punch head is slidable and a lower limb in which is provided an element which co-operates with the punch head to punch the workpiece, the upper and lower limbs being spaced apa-t by a gap to receive the workpiece.

Two bodies may be provided disposed side by side to receive opposite sides of the body in the respective gap.

The or each body may be movable relative to the punch unit by the adjustment means in a direction to transversely of said line.

The adjustment means may comprise an electric motor.

Alternatively, the adjustment means may comprise a fluid operated ram.

The fluid may be a gas such as air or a liquid such as oil.

Sensing means may be provided to sense the position of the or each punch head transversely of the line.

Where the adjustment means is an electric motor the sensing means may comprise an electric motor provided with an encoder.

Alternatively, whether the adjustment means is or is not an electric motor, the sensing means may comprise a position transducer to sense the position of the or each punch head.

The position transducer may sense the position of the body and thereby sense the position of the or each punch head.

The position transducer may provide a linear transducer or a potentiometer.

The adjustment means and the sensing means may be connected in a closed loop arrangement so that the or each punch may be positioned in a desired position transversely of the line.

The sensing means may provide a signal to an electronic control unit in dependence on the position of the or each punch head.

The electronic control unit may be programme to move the each body during passage of a workpiece through the punch machine in order to permit the or each punch head to operate on the workpiece at least at two different lateral positions.

Preferably said different lateral positions are at different longitudinal positions along the line.

The or each fluid operated actuating means may comprise a piston movable in a cylinder under fluid pressure and cushioning means to cushion movement of the piston towards the punching end of its stroke.

The or each actuating means may comprise a position sensor to provide a signal dependent upon the cylinder attaining a position adjacent to the end of its travel in the cylinder in the punching direction to operate said cushioning means.

The piston may be movable in the cylinder in a punching direction by application of a pressure differential applied to the piston by the fluid in the cylinder.

The pressure differential may be applied to the piston by supply of fluid under pressure to the side of the piston remote from the punching end of the stroke and supply of fluid under the same pressure to the opposite side of the piston, the area of the piston on said one side being greater than the area of the piston on the other side.

Movement of the piston in the retum direction may be as a result of connection of said side of the piston to reservoir whilst said other side of the piston remains connected to fluid under pressure.

The cushioning means may comprise a valve operable in dependence on said signal to reduce the pressure differential applied by the fluid to the piston in the direction to cause said movement towards the punching end of the piston stroke.

The valve may interrupt the supply of fluid to the side of the piston remote from the punching end of its stroke and connect the other side of the piston being connected to fluid under pressure.

The valve may be provided in the fluid path to the cylinder and in a first position to direct the fluid during the punching operation and movable to a second position to direct the fluid during said return operation.

The roll forming line may further comprise a plurality of roll passes to bend the workpiece into a desired shape.

The invention will now be described by way of example with reference to the accompanying drawings wherein, Figure 1 is a plan view of a production line comprising metal forming machines according to the present invention, Figure 2 is a cross-section through a punching machine according to the first aspect of the invention in a plane peipendicular to the axis of travel of the metal strip, Figure 3 is a top view of the punching machine of Figure 2, Figure 4 is a cross-section on line 4-4 of Figure 2, Figure 5 is a cross-section on line 5-5 of Figure 2, Figure 6 is a side view, partly in section, of a hydraulic actuator of the punching machine shown in Figures 2 to 5, Figure 7 is a fragmentaiy diagrammatic illustration of part of a hydraulic circuit relating to the hydraulic actuator of Figure 6, Figure 8 is an end view of a roll forming pass of a rolling machine in a first configuration, Figure 9 is an end view of the roll pass of Figure 8 in a second configuration, Figure 10 is a side view of the roll pass of Figure 8, and Figure 11 is a top view of the roll pass of Figure 8.

The line, as shown in Figure 1, of the present example comprises a plurality of machines for forming products from strip metal and comprises an un-coiler 10 of conventional type. Strip metal is unwound from a coil mounted on the un-coiler 10 and passes, via a peeler and flattener as necessary, to a crop shear 11 where the strip is provided with a leading edge which is at right angles to the length of the strip.

The strip then passes to a iooper 12. The formation of a loop on the strip metal enables the line to accommodate, in conventional manner, changes in the speed of the strip passing along the line.

The strip then passes to a punching machine 13 comprising three punch units embodying the first aspect of the invention. If desired the punching machine may comprise any desired number of punch units from 1 upwards.

The punching machine punches holes or notches in the strip.

Downstream of the punching machine 13 is a cut-to-length shear 14 in which lengths of material are separated from the roll to produce a product of a desired length. The discrete separated lengths of punched material are fed by a conveyor, such a skew conveyor, to a roll forming machine 15.

The roll forming machine 15 comprises a plurality of roll passes at least one of which comprises a roll pass as shown in Figures 8 to 11.

Downstream of the roll forming machine is a run out table 16. The production line may be varied from that described above to include as appropriate numbers of the elements described above or other conventionally provided elements depending on the desired product and the nature of the metal being acted upon.

In a punching machine embodying the invention each of the three punch units of the punching machine 3 comprises a punch unit 20 as shown in Figures 2 to 7.

The punch unit 20 comprises a bridge unit having a pair of end plates 21 and a top plate 22. An aperture 21 a is provided in the end plates 21 in which the strip metal is received. A pair of punches 23 are disposed between the end plates 21. Each punch 23 comprises a C-shaped body 24 comprising an upper limb 24a having a punch head 25 slidab) e therein and a lower limb 24b with a gap 24c therebetween. The open side of the C-shaped body 24 of each punch 23 faces longitudinally of the punch unit 20 such that when the strip metal is introduced into the punch unit in the direction shown at A on Figure 4 it may pass through the aperture 2 la of one end plate 21, through the gap 24c of each C-shaped frame 24 and through the aperture 21a of the other end plate 21.

Each punch head 23 has a punching end part 25a.

The left hand i. e. leading, end plate 21 in Figure 4 is provided with upper and lower guides 21b, 21c to guide the strip metal through the punches 23. The lower limb 24b of the C-shaped body 24c is disposed below the punch head 25 and comprises a raised part 26a which houses a die 26b which is to co-operate with the punching end part 25a of the punch head 25 to form an aperture or notch in the sheet metal of a desired configuration depending upon the shape of the punching end part 25a of the punch head 25 and the die of the lower end part 26.

Each punch 23 is attached by bolts 27a to a traversin plate 27 slidable in a guide defined by a base part 28, a side part 28a and a cover part 28b disposed either side of the traversins plate 27, the base part 28, side part 28a and cover part 28b being connected together by bolts 28c. An internally threaded nut part 29 is attached to the traversin plate 27 and is in threaded connection with a threaded rod 30. The threaded rod 30 is housed in roller bearings 31,32 and is driven by a servo motor 33. The base parts 28a, end plates 21 and servo motors 33 are attached to a bridge base unit 34.

Actuating means 35 are provided for each punch 23 comprising a cylinder 36 having a piston 6a and a piston rod 36b. The actuating means 35 further comprises a timing plate 37 having a groove 38 which provides a slideway in which a flange 39 attached to an upwardly extending part 40 of the punch 23 is received. The piston rod 36b of the cylinder 36 acts on the timing plate 37 via a plunler 4 1. Upwardly extending rods 42 attached to the timing plate 37 are received in apertures 43 provided in the top plate 22, and are slidable therein to guide the timing plate 37.

In operation, a worlc piece comprising strip metal is passed into the punch unit in direction A through aperture 21a of the left hand end plate 21.

The strip metal is guided by guides 2 I k and 21 c and passes through the gap 24c and between the punch head 25 and die 26b of each punch 23. Hydraulic fluid is supplied to either or both of the cylinders 35 according to the pattern it is desired to punch in the strip. The or each cylinder 35 acts via plunger 41 on the timing plate 37, which depresses the punch head 25 of the punch 23 such that the punching end part 25a of the punch head 25 passes through the strip metal to form a hole or notch therein.

The punch machine! 6 provides a relative high speed of production with a minimum of noise and vibration.

The actuator 35 is provided with a suitable position indicator for the piston 36. In the present example this comprises a linear transducer 44 having a body 44a fixed to the cylinder 36 and housing element 44b which is movable with the piston 36. The linear transducer, in conventional manner, provides an input to a micro-processor based on a control unit to provide information as to the position of the piston 36a relative to cylinder 36.

The actuator 35 also is provided with a servo valve 45 which is supplied with hydraulic fluid under pressure on a line 46 whilst a line 47 is provided to connect the valve 45 to a reservoir. A branch line 46b is provided to connect the line 46 to the piston rod side of the cylinder 36. The valve 45 is connected by a line 48 to the opposite side of the piston 36a. In the first position of the valve 45 as shown in Figure 7, no fluid flow to or from above the piston 36a is permitted.

In use, when the electronic unit provides a suitable signal to the servo valve 45 it is moved to a second position so as to feed fluid under pressure from line 46 to line 48 to cause piston 36a to move in a punching direction as a result of the pressure differential on the piston due to the area of the piston 36 or the piston rod side thereof being snoaller than the area of the piston on the opposite side. Hence piston rod 36b moves downwardly and thus causes the punch to punch a workpiece.

Shortly before the piston 36a reaches the full mechanical length of the stroke permitted by the length of the relevant region of the cylinder 36 the linear transducer 44 provides a signal to the electronic control unit which sends a signal to the valve 45 to cause the valve to move to a third position so that the side of the piston 36a opposite to the piston rod 36b is connected by the line 48 to reservoir. The piston rod side of the piston 36a is connected by the line 46b to fluid under pressure. Further downward movement of the actuator as a result of inertia is prevented by a reversed pressure differential acting on the piston 36a and the piston 36a and hence the piston rod 36b and the punch is moved upwardly by the pressure of oil in the lines 46 and 46b oil above the piston 36a being returned to reservoir on lines 48 and 47. As the piston moves upwardly the linear transducer 44 senses when it approaches the end of its mechanically permitted stroke and the servo valve 45 is moved to its first position in which flow of fluid from above the piston is prevented. As a result upward movement is cushioned.

Although in the present example the position of the piston 36a is determined by a linear transducer other suitable means may be provided such as a potentiometer. In all cases a closed loop electronic circuit using a micro- processor controlled electronic control unit programme with a suitable software program is used.

The arrangement described above allows the punch to operate so that the piston 36a is cushioned from both punching and retum movement and can be accurately brought to rest at the top and bottom of its working stroke which is within the full mechanical stroke of a piston within the cylinder.

In addition the position of the top and bottom of the working stroke can be accurately adjusted in small steps for example of 0.1 mm to allow for setting adjustrnents for the simplicity of setting the tooling after for example re- grinding of the tool rig or other re-setting. Such adjustment may be conveniently provided in the software program so as to be conveniently set up by a user.

When it is desired to vary the location of the punched holes or notches, e. g. motors with encoders on setting up the line for a production run the servo motors 33 are actuated to move the or each punch 23 laterally to the desired position. The position of the or each punch 23 is monitored electronically and be fed back to a control system which may funther control the motors, thus providing a closed loop with feedback and the or each punch unit can thus be computer controlled to quickly vary the punch setting.

To alter the shape or size of the punched holes, each punch 23 can be easily removed from the traverse plates 27 by removing the bolts 27a and replaced by a further punch 23 having punching end parts 25a of a desired size or shape.

Where it is desired that both punches always operate together only to punch pairs of holes, a single timing plate 37 engaging both punches 23 can be provided, and actuated by a single cylinder 36. Operation of the cylinder will operate both punches 23 at the same time. In the configuration comprising a pair of cylinders 36 as shown in Figures 2 to 5, the cylinders may be operated independently to provide pairs of punched holes or other punch patterns as desired. Further alternatively, only a single punch 23 may be provided if desired. The punch unit 20 is therefore easily and quickly re-configurable to provide a punch pattern having a particular spacing size or pattern of holes as required.

If desired, and as in the present example, three longitudinally disposed punch units 20 are provided and the metal strip is moved longitudinally to position a desired portion thereof in operative relationship with each punch unit to that a desired pattern of apertures and/or notches may be achieved.

Although in the above example the adjustment means have comprised servo motor 23 having encoders, if desired electric motors not having an encoder could be provided with a suitable transducer to provide feedback to the electronic control unit. Further alternatively instead of providing an electric motor suitable hydraulic or pneumatic cylinders with a suitable transducer may be provided to move the punches transversely of the line.

When during operation of the line, it is desired to vaiy the lateral position of the punched holes or notches at the same or different longitudinal positions of the workpiece the servo motors 33 may be actuated, during operation of the line, so as to move the or each punch 23 laterally to the desired initial position and then to a desired further position or further positions. In such a case when the workpiece is in a first longitudinal position corresponding to a first lateral position of the punch or punches the or each punch 23 will then be actuated to form a desired hole or notch arrangement, then the workpiece is moved to a desired second longitudinal position and the servo motor or motors 33 actuated to move the or each punch laterally to the second desired lateral position whereupon the or each punch is then actuated again to form a desired hole or notch configuration and similarly for any other desired position either laterally and/or longitudinally at which the or each punch is desired to be operated.

As in the case of operation of the servo motors 33 on set-up of the machine, as described above, the position of the or each punch 23 is monitored electronically and fed back to a control system which further controls the motors 33 thus providing a closed loop with feedback so that the or each punch limit is thus computer controlled to quickly vary the punch setting during operation of the machine. Of course if a different configuration of hole or notch is required at different positions then a different set of punches would be used but again the lateral position of the or each additional punch may be varied either on set-up or in use as described above by operation of the appropriate servo motors 33.

A guide table is provided for the lateral guiding of strip upstream and downstream of the punching machine.

A roll forming machine embodying the invention comprises a plurality of roll forming passes 50 one of which is shown in Figures 6 to 9. Each successive pass progressively fours the work piece from a flat shape to a final shape, in the present example to be described hereinafter a C-shape, and punched with a pattern of apertures provided by a punching machine as described hereinbefore. The punching machines alla roll forming machines as described herein may of course be used independently as required.

The first pass wi ! ! now be described by way of example but it will be accepted that apart from the form of the individual rolls all the passes will be similar.

Each roll forming pass 50 comprises a first stand 51 and a second stand 52 disposed alongside one allothel, mounted on a base unit 5 la, 52a respectively. Base units 5 1 a, 52a may be mounted such that they are moveable in a lateral direction transverse to the direction of travel of the work piece to vary the separation between the first stand 51 and the second stand 52. Either or both stands may be moveable in this fashion, and may be moved either by a manual technique such as a hand wheel, or by semi-automatic or fully automatic control systems.

The work piece may be driven by drive rollers provided in drive sections, not shown, in which the work piece is passed between a pair of drive rollers. The pinch between the drive rollers may be adjusted in accordance with the gauge of the work piece. Where the drive section is at least partly laterally adjustable in similar fashion to the base units 51a, 52a of the roll forming pass described above, drive may be provided to the drive rollers from a fixed drive source by a universal shaft.

The first stand 5 ! comprises a first upright 53a and a second upright 53b attached to the base part 5 la. The upright parts 53a 53b are connected at their upper ends by a top plate 54. Each upright 53a, 53b comprises a projecting part 55a 55b projecting towards the opposing upright part and parallel thereto.

Received on the projecting parts 55a 55b is a slider plate 56 having recesses 56a, 56b at either end in which corresponding projecting parts 55a, 55b are received. The slider plate 56 is connected to a piston of a pneumatic ram 59 mounted on the top plate 54. The slider plate is thus moveable in a generally vertical direction by the ram 59 guided by the projections 55a, 55b. Mounted on the base plate 51a are a pair of upright guide rods 61a, 61b received in corresponding holes 62a, 62b in the slider part 56. A stop means 63 is provided attached to the base plate 51a disposed between the rods 61a 61b to limit downward movement of the slider 56.

Mounted on the slider plate 56 is a first roller 64 having a fi-usto-conical portion 64a tapering in a direction away from the slider plate 56 with a generally cylindrical portion 64b at the narrow end of the frusto-conical portion 64a. The roller 64 is mounted on a shaft 65 by bearings 65a. The shaft 65 has an eccentric mounting part 66, the eccentricity is not shown in the figures, which is received in bearings 66a in a sleeve 67 fixed to the slider 56. The roller 64 is mounted upon the shaft 65 which has a longitudinal axis which is offset from a longitudinal axis of the mounting part 66 received in the bearings 66a. An end portion of the mounting part 66 is attached to a lever 68, the lever 68 being offset with respect to the part 66. The end of the lever 68 distant from the mounting part 66 is attached to one end of a pneumatic ram 69, the other end of the ram 69 being attached to the slider 56. The bore side of the cylinder 69a of the pneumatic ram is supplied with air under pressure, thus acting to move lever 68 in an anti-clockwise direction as seen in Figure 8, into engagement with a first stop 68a The roller 64 is held on the shaft 65 by an end cap 65b.

The first stand 51 furcher comprises an upper roller 70 and a lower roller 71. The rollers 70 and 71 each comprise a first generally cylindrical portion 70a, 71a disposed away from the stand 51 and a frusto-conical portion 70a, 71a having its widest part adjacent the cylindrical portion 70a, 71a and tapering towards the part 51.

The lower roller 70 is mounted on shaft 72 received in bearings 72a and held on shaft 72 by an end cap 72b. The shaft 72 is fixedly mounted in a sleeve 73 provided in the slider 56.

The upper roller 69 mounted on a shaft 74, by bearings 74a. The shaft 74 has an eccentric mounting part 75, the eccentricity is not shown in the figures, which is received in bearings 75a provided in the slider 56. Again, the shaft 74 has a longitudinal axis which is offset from the longitudinal axis of the mounting part 75. As with the first roller 64 an end portion of the mounting part 75 is provided with a lever 77 offset from the mounting part 75 and attached pneumatic ram 78. The other end of the pneumatic ram 78 is connected to the slider 56. The pneumatic ram 78 comprises a cylinder 78a, air under pressure being supplied to both sides of said cylinder 78a such that the pneumatic cylinder 78 acts on a lever 77 to rotate it in a generally anti- clockwise direction as seen in Figure 8 into engagement with a stop 74a.

The second stand 52 comprises a first roller 90 having the same features and being mounted in the same fashion as roller 64 and a lower roller 91 having the same features and being mounted in the same fashion as lower roller 70 of part 51.

In operation, the first stand 51 and second stand 52 are disposed opposite each other as shown in Figure 6 such that rollers 64 and 90 are coaxial and rollers 70 and 91 are coaxial.

Strip metal is introduced into the roll forming unit in the direction B shown in Figure 8. The metal strip in between the rollers 64,71 and 90,91 in the present example, is formed to the first shape of rolling a C-shaped profile.

Forming of the metal strip to a desired profile is accommodated by the pressure applied to the ram without causing any movement of the ram. However, dependant on the gauge of the metal strip introduced, the resulting resistance of the strip arising from the gauge of the workpiece may force the roller 64 upwardly, forcing the shaft 65 to rotate about the axis of mounting part 66, thus acting to increase the gap between roller 64 and roller 71. This movement is opposed by the ram 69 acting on lever 68 to rotate the shaft 65 about the axis of the mounting part 66 producing an increased downwards force on the roller 65.

The roller 91 on the stand 52 operates in similar fashion. The roll forming unit thus accommodates strip metal of different gauges without requiring any external alteration. Clockwise movement of the lever 68 is limited by a stop 69b. The eccentric mounting of the roll 64 restrains downward movement of the roll 64 as a result of downward force applied thereto by the introduction of the 7 between the roll 64 and the roll 71.

If it is desired to produce an article having a Z-shaped profile rather than a C-shaped profile then, prior to the introduction of strip metal into the roll forming unit, the roll forming unit is moved to the configuration shown in Figure 7. By actuating the pneumatic ram 59, the slider 56 is moved downwards until its lower surface abuts the stop 63. In this position, the gap between the rollers 65 and 69 is aligned with the gap between rollers 90 and 91.

Strip metal introduced in the direction B thus has opposite edges folded in opposite directions at the first stage of forming a Z-shaped profile.

The forming of the metal strip to the desired profile is accommodated by the pressure applied to the ram 78 without causing any movement of the ram.

However, dependent upon the gauge of the metal strip introduced the resulting resistance of the strip arisillg from the gauge of the workpiece may force the roller 70 upwardly, forcing the shaft 74 to rotate about the axis of the mounting part 75 by acting to increase the gap in the roller 64 and the roller 70. This movement is opposed by the ram 78 acting on lever 77 to rotate the shaft 74 about the axis of the mounting part 75 to produce an increased downwards force on the roller 70. The roller on the stand 52 operates in a similar fashion with the C-shaped embodiment described hereinbefore. Clockwise movement of the lever 77 is limited by a stop 79b.

The roll forming unit is thus quickly and easily adaptable to provide one of two different rolling profiles and to accommodate different gauges of metal.

The roll forming unit is operated in conjunction with drive means comprising at least one set of non-shaping driven rollers to move the workpiece. At least the first pass in a roll forming machine 15 is not driven. Although in the majority of cases the roll-forming passes are kept separate from driven rollers it will be appreciated that one or more roll forming passes may be provided with drive means. The absence of drive means for the forming rollers enables the rollers to be moveable as set out above to accommodate different metal gauges without the necessity of providing means to transfer drive to the rollers. Further, if the rollers were driven they would simultaneously be trying to drive metal strip and provide a bending force. This could lead to inconsistent driving speed of the strip and cause slip and damage to the strip and machinery.

A line may thus comprise at least punching machines 12 comprising one or more punch units 20 and/or rolling machines 15 comprising one or more rolling units 50.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilise for realising the invention in diverse forms thereof.