GB2168277A - Two-roll sheet-bending or plate- bending machine - Google Patents

Abstract

A framework (1) with uprights (2, 3), supports a roll (12) with an elastic cover (13) and an associated drive (17) for its rotation, by means of a pair of support jaws (10, 11) pivoted on a crosspiece (9) between the uprights which jaws can be pivoted upwards either by a prior adjustment device or by a piston (19, 20) in use. The machine further has a top crosspiece (33) mounted between the uprights (2, 3), movable to select a vertical wall (34 or 103) with a support means (35) at a lower edge for accommodating a shaping roll (5 or 107) against roll (12, 13) to permit the operation of bending a sheet workpiece (14). Devices (36, 37) are provided on each wall (34 or 103) for retaining the shaping roll (5 or 107) generally in position during removal of the bent workpiece (14) from the machine by retracting roll (12). <IMAGE>

Description

SPECIFICATION Two-Roll Sheet-Bending or Plate-Bending Machine The present invention relates to the art of working metals and other materials by application of pressure, and more particularly it relates to two-roll sheet-bending or plate-bending machines.

The invention can be used for bending sheet or plate metal stock into tubular parts as used in the aircraft and automotive industries and in chemical engineering.

The invention can also be utilized for bending various parts of permenant structures, e.g. chutes, reflectors, etc.

The present invention consists in a two-roll sheet bending or plate bending machine comprising a base frame with uprights; a selectively interchangeable shaping roll with a hard peripheral surface, extending in a direction between the uprights; a roll with a resilient cover surface, forming in use a nip with the said shaping roll, provided with drive means for rotation, and mounted on means capable of moving it radially towards or away from the shaping roll; and a crosspiece extending between the uprights comprising a wall or web the longitudinal edge of which carries support means for, ut permitting rotation of the shaping roll and the-ends of which carry retaining devices to hold the shaping roll when the resilient surfaced roller is withdrawn.

Preferably, the crosspiece comprises a plurality of such walls or webs each carrying supports adapted for use with a different diameter of shaping roll, the crosspiece being capable of selective rotation about its axis to preserve for use a desired longitudinal edge and its support means.

With such machines it has become possible to mount a quantity of supports sufficient for ensuring adequate rigidity of a shaping roll of a diameter of 30 mm or more. Moreover, the supports are of a dimension enabling them to be accommodated to within the outline defined by the minimum inner diameter of the tubular article being bent. With the wall or web being of this thin-walled kind, it becomes possible in a single step to perform the bending of the article to one half of the perimeter of its circular profile. The second step would therefore conclude the bending of the article of the circular profile. The shaping roll is urged against the supports by the action of the force required for the bending.With this load relieved, the shaping roll separates from the supports under its own weight and is retained with respect to the wall by the retaining devices positioned at the ends of this wall as described more fully below. This arrangement of the shaping roll in the sheet bending machine provides for quick removal or delivery of the workpiece after the bending, as it is no longer necessary to release the roll from its supports, and the workpiece can be removed from the machine simply by being moved along the generatrix of the roll.

Preferably, the support means is in the form of rollers extending along two parallel axes, to receive the circumference of the shaping roll.

The maximum value of the angle between lines tangent to the peripheries of such rollers at the points of their engagement with the shaping roll should usually be not greater than 1400.

With the supports being in the form of supporting rollers, the loss of effort required to overcome the friction forces when the shaping roll is rotated is minimized. Our experiments and research, indicate that the arrangement of the supporting rollers in two parallel series provides for adequate stability of the shaping roll.

Each support roller axis may comprise supporting rollers arranged along the entire length of the shaping roll. The effectiveness of such an arrangement is determined from the linear load acting upon the shaping roll, the effort applied to the support and the permissible sag of the shaping roll.

As in most cases in the bending of tubular parts or articles stringent requirements are put before the permissible length of the underbent end portions, the conducted research has proved that the majority of the parts or articles need to be bent under loads requiring that the support be arranged along the entire generatrix of the roll.

Usually, such support roller axis comprises a plurality of rollers. It may be expedient for the machine to comprise a mechanism or configured wall for moving at least one opposed roller of the supporting rollers away from the periphery of the shaping roll. The mechanism may include a hinged wall portion and a hydraulic cylinder capable of pivoting this portion to remove at least one opposed pair of rollers. This feature is valuable for bending thin-walled tubular articles when the bending of the edges must be conducted under great efforts requiring the presence of all the supporting rollers along the generatrix of the shaping roll, but the bending of the main outline can be conducted under a substantially smaller linear load, i.e. some of the rollers can be moved out of engagement with the shaping roll.If the length of the thus-liberated area of the roll is equal to, or in excess of, the length of the article to be bent, the bending can be conducted in a single step or pass. In this way the productivity of the bending operation may be enhanced.

In another preferred feature the retaining devices for the shaping roll comprise, at each end of the roll, a retractable stud biassed into a circular recess, or an annular groove, of larger wall to wall dimension than the stud, in the roll end face: retraction of each stud thereby allowing replacement of the roll, and engagement of each stud thereby allowing for roll-rotation over a range of displacements but for roll-retention when the resilient surface roll is fully retracted.

This type of structure provides for quick detachment and positioning of the shaping roll when the type or size of the articles to be bent is changed. Another advantage of this structure is the fact that if the walls of the grooves of interchangeable shaping rolls are the same thickness, it is no longer necessary to reposition the housing of the device at shaping roll changes when the rolls are of different diameters.

Preferably, the invention further comprises a mechanism for a preadjustment of the resilientcovered roll position in accordance with the diameter of the selected shaping roll, operatively connected to the means capable of moving it radially towards or away from the shaping roll in substantive use.

One way of doing this is to provide that the resilient covered roll and its rotation drive means are mounted on two pairs of arms pivoted on a crosspiece between the two uprights and pivoted towards or away from the shaping roll by at least one hydraulic pistonicylinder arrangement itself mounted on a vertically adjustable support for preadjustment in dependence on the selected shaping roll diameter. Thus each arm of pairs may be provided with a separate pistonicylinder arrangement, each mounted on a separate vertically movable screw shaft with a common rotary drive for preadjustment.

The incorporation of the mechanism for adjustment-wise displacement eliminates the necessity of placing the rolls each time into the "zero penetration" position, i.e. of initially bringing the shaping roll and the roll with the elastic cover into the "touch engagement" position. The incorporation of the preadjustment mechanism provides for determining the required position of the resilient covered roll with respect to the wall at the shaping roll changes, even in the absence of the shaping roll.

For convenience, the device may further comprise a scale fixed in relation to the framework, and a flexible measuring band fixed to the means capable of moving the resilient-covered roll radially towards and awayfrom the shaping roll in substantive use: the scale having subdivisions corresponding to values of such radial displacement in use and the band having subdivisions relevant to the diameter of a selected shaping roll, whereby preadjustment, by moving both the preadjustment mechanism and the radial-displacement means, can be controlled by the band initial position, and radial displacement in use can be controlled by the band movement along scale dimensions. This structure is very simple, and the information on the depth of the penetration of the shaping roll into the elastic cover is both easily readable and obvious.

The present invention will be further described with reference to the accompanying drawings wherein: Fig. 1 is a general front view of a two-roll sheet-bending machine embodying the invention; Fig. 2 is a section on line Il-Il of Fig. 1; Fig. 3 is a brokan-away view of part of Fig. 2, showing on a larger scale a supporting roller in engagement with a shaping roll; Fig. 4 is a partial view of a modification of the machine, comprising a mechanism for moving away some of the supporting rollers, in accordance with the invention; Fig. 5 is a broken-away view of part of Fig. 1 showing on a larger scale a device for retaining the shaping roll; Fig. 6 is a general cross-sectional view of a mechanism for adjustment displacement of the roll with an elastic cover, according to the invention; and Fig. 7 is a view in the direction of arrow A in Fig. 6.

The two-roll sheet- or plate-bending machine embodying the invention comprises a boxiike framework structure 1 having secured to the ends thereof uprights 2 and 3 which are interconnected by a cross-tie 4. The machine further comprises a changeable shaping roll 5 with a hard peripheral surface 6 and being mechanically associated with the uprights 2 and 3 for free rotation. The uprights 2 and 3 have bores 7 and 8, respectively, made therein for a shaft 9. This shaft 9 carries left-hand and right-hand jaws 10 and 11 by which is rotatably mounted roll 12 with an elastic cover 13.

This roll 12 and its elastic cover 13 acts to bend a sheet or plateworkpiece 14 (Fig. 2) against the shaping roll 5. It has a metal core 15 on which rings of an elastic material, e.g. polyurethane, are pressfitted. Roll 12 with the elastic cover 13 is rotatably drivable by a drive 17 (Fig. 1) (e.g. a hydraulic motor) mounted on the right-hand jaw 11, and radially displaceable by a mechanism 18. The radial displacement mechanism 18 is in the form of hydraulic cylinders 19 and 20 mounted with aid of pivot studs 21 and 22 on respective brackets 23 and 24 secured to the framework 1. The respective piston rods 25 and 26 of the hydraulic cylinders 19 and 20 have respective lugs 27 and 28 received on the respective slots 29 and 30 of the jaws 10 and 11 and connected therewith through respective pivot studs 31 and 32.

In accordance with the invention, the machine further comprises a crosspiece 33 mounted between the uprights 2 and 3 and carrying a wall or web 34 on which there is mounted a support 35 for accommodating the shaping roll 5. the ends of this wall 34, there are mounted devices 36 and 37 for retaining the shaping roll 5 during removal or deliveryoftheworkpiece 14.

The crosspiece 33 is a rigid beam supported at its ends by supporting members 38 and 39 received, respectively, in the uprights 2 and 3. Furthermore, the crosspiece 33 terminates in and is fixed in openings 42 and 43, respectively in flanges 40 and 41. Fixing is effected with the aid of tapering pins 44 and 45, respectively, located in the openings 42 and 43 of the flanges 40 and 41 and mounted on the respective handwheels 46 and 47. The cross-piece 33 has a slot 48 (Fig. 2) to receive the upper portion of the wall or web 34. The bottom portion of the wall 34 has an expanded end 49 to accommodate the support 35forthe shaping roll 5.

In the embodiment shown the support 35 of the shaping roll 5 is in the form of a plurality of supporting rollers 50 (Fig.3) mounted on shafts 51 carried by the expanded end 49 of the wall 34, arranged in two parallel series along the generatrix of the shaping roll 5. The rollers 50 are adapted to be engaged by the shaping roll Sin operation.To maintain the shaping roll 5 in permanent engagement with the rollers 50 while the device is applying pressure to bend the work-piece 14, the angle a (defined between the tangents drawn to the peripheries of the two series of the rollers 50 at the points of their engagement with the surface 6 of the shaping roll 5) is generally not in excess of 1400. It can be ensured by appropriate choice of distance "1" between the centres of the rollers 50 and the diameter "d" of the shaping roll 5, selected to correspond to the diameter of the workpiece to be bent. The minimum value of the angle a is limited by the maximum permissible load to be exerted of the rollers 50.

To bend workpieces of sheet or plate metal stock 0.5 to 3.0 mm thick and of high-strength metals and alloys, the rollers 50 are arranged along the entire generatrix of the shaping roll 5, as shown in Fig. 1.

To bend relatively short workpieces of thin-sheet metal stock (of thickness up to 0.5 mm, and made of relatively soft metals and alloys) in one step, a machine according to the invention may include a mechanism 52 (see Fig. 4) for moving some of the rollers 50 away from the periphery 6 of the shaping roll 5. This mechanism comprises a hydraulic cylinder 53 whose piston rod 34 is connected via a rod 55, a bracket 56 and a carrier member 57 with those of the rollers 50 which are to be moved away.

The bracket 56 is secured on a carrier member 57, of a shape corresponding to the respective shape of the wall 34 and received in a cutout 58 made centrally in relation to the wall 34. The cutout 58 defines lugs 59 received in respective slots 60 of the carrier member 57. Carrier member 57 is connected with the wall 34 by means of a shaft 61. The body 62 of the hydraulic cylinder 53 is mounted on the crosspiece 33 with aid of another bracket 63.

In accordance with the invention, there are mounted at the ends of the wall 34 (Fig.1) devices 36 and 37 for retaining the shaping roll 5. As shown in Fig.5, a typical device 36 may include a bracket 64 mounted on the end face of the wall 34 and a stud 65 having its one end received in a blind opening 66 of the bracket 64 for axial displacement, and its other end receivable in an annular groove 67 in the end face of the shaping roll 5. In its working position the stud 65 is urged into this groove 67 by a compression spring 68 accommodated in the blind opening 66 of the bracket 64. To retract the stud 65 for displacement of the shaping roll 5, there is provided a knob 69 connected with the stud 65 through a bore 70 in the bracket 64.

The other retaining device (37) has an identical and opposite construction, and is therefore not shown in Fig. 5.

To adjust the machine for a different diameter "d" (Fig.3) of the shaping roll 5, the machine according to the invention may further comprise a mechanism 71 (Fig. 6) for initial adjustment-displacement of the roll 12 (Fig.1) and the elastic cover 13 relatively to the wall 34, operatively connected with the mechanism 18 for working radial displacement of the roll 12 with the elastic cover 13.

There is shown in Fig. 6 mounted on one hydraulic cylinder 19 a part of the mechanism 71 for radial displacement of the roll 12 with its elastic cover 13. A like mechanism may be mounted on cylinder 20. The operative connection of each adjustment mechanism 71 (adjustmentdisplacement) with its relevant operating mechanism 18 (radial displacement) includes load screws 72 each one of which at its upper ends connected via a pivot 73 and bifurcated member 74 with the respective hydraulic cylinder 19 or 20 (Fig.

1). The other end of the screw 72 (Fig. 6) is free. Each load screw 72 is associated with a nut 76 with a worm-wheel rim 76, supported by a thrust bearing 77 which, in its turn, is supported by the housing 78 of the adjustment displacement mechanism 71, mounted on the framework 1. Each housing 78 of the adjustment displacement mechanism 71 has a respective bearing 79 or 80 for a common transverse worm-gear shaft 81. The arrangement ensures synchronous displacement of both load screws 72 during adjustment, during which the worm-gear shaft 81 (common to both worm-wheel rims 76) is rotatable by a drive 82 including a reduction gear 83 and an electric motor 84.

In the machine according to the invention the mechanism 71 for adjustment-displacement of the roll 12 (Fig. 1) with the elastic cover 13 further includes a scale 85 (Fig. 6) mounted on the framework 1 and a flexible band 86 operatively connected with the mechanism 18.

The scale 85 (Fig. 7) is connected with the framework 1 (Fig. 6) via a plate 87 mounted on brackets 88 and 89 which, in their turn, are mounted in a housing 90 connected to the framework 1 via upright 2. The scale 85 has divisions 91 (Fig. 7) corresponding to respective values of the radial diplacementofthe roll 12.

One of the two housings 78 (Fig.6) of the mechanism 71 has attached thereto one end of the flexible band 86, which then runs over guide rollers 92, 93, 94, 95 and 96 mounted, respectively, on the bracket 97 of the housing 78; on the brackets 88 and 89; and on the brackets 98 located on the bifurcated member 74 and therefore moving with the housing 99 of the hydraulic cylinder 19. The other end of the flexible band 86 carries a weight 100 for tensioning the band. An opening 101 in the upright 2 of the framework 1 provides for passage of the band 86.

The band 86 itself has scale divisions 102 (Fig. 7) depending upon the respective diameter "d" of the chosen shaping roll 5, 107 or 108.

The diameter "d" of the shaping roll 5 or 107 or 108 is selected in dependence upon the diameter, wall thickness and material of the articles to be produced by bending. Depending on the range of the diameters of the shaping rolls 5 or 107 or 108 necessary for bending the required range of articles in a given sheet-bending machine, a related number of supports 35, ensuring stability of the shaping rolls Son the rollers 50, are also provided. The machine illustrated in Fig. 2 has a crosspiece 33 carrying three walls or webs 34, 103 and 104 with the respective supports 35, 105 and 106, supporting the respective shaping rolls 5, 107 and 108.

Correspondingly, in Fig. 7 the flexible band 86 has three scales 102, 109 and 110 of divisions corresponding to the respective diameters of the shaping rolls 5, 107 and 108 (Fig. 2) cooperating with the supports 35,105 and 106.

The housing 90 accommodating the ruler 85 and the band 86 is covered by a transparent panel 111.

Adjustment of the two-roll sheet-binding machine prior to operation is as follows.

Firstly, handwheels 46 and 47 (Fig. 1) are rotated so that the tapering pins 44 and 45 become withdrawn from the openings 42 and 43 in the flanges 40 and 41.

This permits crosspiece 33 to be rotated on its shaft and thereby to position vertically the respective wall or web 34,103 or 104 corresponding to the selected shaping roll 5, 107 or 108, with the rollers 50 facing downward. The value of the angle a defined by lines tangent to the peripheries of the rollers 50 at the points of their engagement with the shaping roll 5 will generally not exceed 1400.

The knob 69'(Fig. 5) is operated to retract the stud 65 against the effort of the compression spring 68, for the end of the stud 65 to be withdrawn into the opening 66. The corresponding stud is withdrawn from the other end also.

The shaping roll 5 (Fig. 2) with its hard peripheral surface 6 and the diameter "d" as chosen for the particular diameter, thickness and material of the workpiece 14to be bent, is located substantially parallel with the shafts of the rollers 50, and the knob 69 (Fig.5) is released. This permits spring 68 to urge the end of the stud 65 into the annular groove 67 of the shaping roll 5. The opposite but equivalent stud 65 is introduced into the other annular groove 67 of the shaping roll 5 in the opposite end face.

Then to adjustthe roller position priorto operation the electric motor 84 (Fig. 6) is energized.

The work gear shaft 81 is driven by reduction gear 83 and thus drives the worm-wheel rim 76 of the nut 75. The nut 75 rotates on its thrust bearing 77, causing translational motion of the lead screw 72, lifting the cylinder 19 bodily up or down.

The guide roller 92 moves upward jointly with the bracket 98 mounted on the bifurcated member 74 and thus with the load screw 72 itself, pulling the band 86 which runs about the rollers 96,95,94 and 93 and lifts the weight 100. While thus running, the band 86 has those divisions 102 corresponding to the diameter "d" of the respective shaping roll 5 moving relative to the scale 85. The electric motor 84 is energized until the division corresponding to the actual diameter "d" of the actual shaping roll 5, 107 or 108 as retained on the studs 65 is brought against the division 91 of the ruler 85. This correlates to the required value of penetration of ths shaping roll 5 into the elastic cover 13 of the roll 12.

This completes the prior adjustment operation.

Now the machine is operated as follows.

The working fluid is fed under pressure into the under-piston spaces of the hydraulic cylinders 19 and 20, and the respective piston rods 25 and 26 of these cylinders 19 and 20 act through the lugs 27 and 28 upon the respective jaws 10 and 11,so as to turn the latter about the shaft 9.

Thus, the roll 12 with its elastic cover 13 is brought toward and into engagement with the shaping roll 5 (say) and presses the latter against the rollers 50 of the support 35. Further displacement of the roll 12 with the elastic cover 13 causes deformation of this elastic cover 13 by penetration of the shaping roll 5 thereinto.

The workpiece 14 is then fed into the nip of the rotating rolls 5 and 12, to be moved along by friction. The elastic deformation of the elastic cover 13 bends the workpiece 14abouttheshaping roll 5.

The shaping roll 5 bears upon supporting rollers 50 which are arranged along its entire generatrix, and so is supported against longitudinal bending, its sag does not exceed the permissible value.

The roll 12 is rotated until one half of the perimeter of the workpiece 14 is bent, which is made possible owing to the wall.or web 34 being of the thin-wall structure and thus not hindering the bending (note Fig. 2 configuration). (In practice the feed of the workpiece 14 is continued after its edge has engaged the wall 34, but its resilient bending can be continued until one half of the perimeter of the workpiece 14 has passed through the nip of the rolls 5 and 12). Then the drive 17 rotating the roll 12 with the elastic cover 13 is de-actuated. Working fluid under pressure is fed into the above-piston spaces of the hydraulic cylinders 19 and 20, the piston rods 25 and 26 move down and the jaws 10 and 11 consequently move down. The roll 12 and its elastic cover 13 thus become moved away from the workpiece 14 and from the shaping roll 5.The latter however hangs by its annular grooves 67 on the two end studs 65. Then the other half of the perimeter of the workpiece 14 is bent, in an operation similar to that described above by repeating the penetration of the shaping roll 5 into the elastic cover and rotating the rolls 5 and 12.

Bending of workpieces using mechanism 52 (for withdrawing some of the rollers 50 from the periphery of the shaping roll 5) is effected as follows: Short thin-sheet workpieces of relatively soft metals, of a length equal to or short of the length of the carrier member 57 (Fig. 4) may bend by operating the cylinder mechanism 62 for moving some of the rollers 50 away from the periphery 6 of the shaping roll 5.

The prior radial displacement and rotation of the roll 12 are effected in the way similar to the one described above. The workpiece is then fed through the nip of the whole of rotating rolls 5 and 12 (using 5--10 thicknesses of the workpiece) so as to prebend the edge of the workpiece. The rotation is discontinued and then reversed to release the workpiece from the nip of the rolls 5 and 12. A similar operation is performed at the other edge of the workpiece.

Then the rotation of the roll 12 is stopped, and the roll is moved into its lowered position to relieve the roll 5 from the working effort.

Now the working fluid under pressure is fed into the lower space of the hydraulic cylinder 53, to rotate the carrier member 37 (carrying some of the rollers 50) by means of the bracket 56, piston rod 54 and rod 55 about the shafts of the lugs 59, so that the cutout 58 in the wall 34 is opened and the roll 5 has less pressure exerted upon it.

The radial displacement and rotation of the roll 12 with the elastic cover are again effected, as described above but using the thin individual workpieces into the pre-bent edges, fed into the nip of the rolls 5 and 12, to be bent in one pass or step into a circular shape. When the roll 12 is eventually lowered again the bentworkpiece may move along the generatrix of the shaping roll 5. Working fluid is then fed under pressure into the lower space of the hydraulic cylinder 53 to restore the carrier member 57 into its initial position.

The two-roll sheet-bending or plate-bending machine as shown above can be used to high economic and technological effect in small series production of wide ranges of tubular articles and parts from sheet stock of aluminium and titanium alloys (e.g. for aircraft antifeeze and life-support systems) and also of corrosion-resistant steel grades. The machine may be used for bending articles with thickness up to 1.5 mm (titanium alloys) or 3.0 mm (aluminium alloys) with the length of the tubular articles produced being up to 1600 mm. The use of the machine disclosed herein, instead of sheet-bending or brake presses, in the manufacture of tubular articles and parts offers the possibility of increasing the productivity of the bending operation fivefold, while reducing the volume of manually performed.finishing operations to jesus than one half of previous values.

Claims (15)

1. A two-roll sheet bending or plate-bending machine comprising: a base frame with uprights; a selectively interchangeable shaping roll with a hard peripheral surface, extending in a direction between the uprights; a roll with a resilient cover surface, forming in use a nip with the said shaping roll, provided with drive means for rotation, and mounted on means capable of moving it radially towards or away from the shaping roll; and a crosspiece extending between the uprights comprising a wall or web the longitudinal edge of which carries support means for, but permitting rotation of the shaping roll and the ends of which carry retaining devices to hold the shaping roll when the resilient support roller is withdrawn.

2. A machine as claimed in claim 1, in which the crosspiece comprises a plurality of such walls or webs each carrying supports adapted for use with a different diameter of shaping roll, the crosspiece being capable of selective rotation about its axis to present for use a desired longitudinal edge and its support means.

3. A machine as claimed in claim 1 or 2 in which a web thickness and support means dimension permit a sheet workpiece to be bent into a semicircular section.

4. A machine as claimed in claim 1,2 or 3 in which the support means is in the form of rollers extending along two parallel axes, to receive the circumference of the shaping roll.

5. A machine as claimed in claim 4 in which the selected diameter of the shaping roll is such that the maximum value of the angle between lines tangent to the support roller peripheries at points of contact with the shaping roll is not greater than 140 .

6. A machine as claimed in claim 4 or 5 in which each support roller axis comprises rollers extending along the whole length of the shaping roller.

7. A machine as claimed in claim 4, 5 or 6 in which each support roller axis comprises a plurality of rollers.

8. A machine as claimed in claim 7 in which the wall is configured in such a way that a portion of the longitudinal edge, carrying at least one opposed pair of support rollers, can be selectively moved away from engagement with the shaping roll.

9. A machine as claimed in claim 8 having a hinged wall portion and a hydraulic cylinder capable of pivoting the hinged portion from the plane of the rest of the wall so as to remove at least one pair of opposed rollers at the longitudinal edge from engagement with the shaping roll.

10. A machine as claimed in any one preceding claim in which the retaining devices for the shaping roll comprise, at each end of the roll, a retractable stud biassed into a circular recess, or an annular groove, of larger wall to wall dimension than the stud, in the roll end face; retraction of each stud thereby allowing replacement of the roll, and engagement of each stud thereby allowing for roll-rotation over a range of displacements but for roll-retention when the resilient surface roll is fully retracted.

11. A machine as claimed in any one preceding claim, further comprising a mechanism for preadjustment of the resilient-covered roll position in accordance with the diameter of the selected shaping roll, operatively connected to the means capable of moving it radially towards or away from the shaping roll in substantive use.

12. A machine as claimed in claim 11, in which the resilient covered-roll and its rotation drive means are connected on two jaws or arms pivoted on a crosspiece between the two uprights and pivoted towards or away from the shaping roll by at least one hydraulic/piston cylinder arrangement itself mounted on a vertically adjustable support for preadjustment in dependence on the selected shaping roll diameter.

13. A machine as claimed in claim 12, in which each arm or jaws is provided with a separate piston/cylinder arrangement, each mounted on a separate vertically movable screw-shaft with a common rotary drive for preadjustment.

14. A machine as claimed in claim 11, 12 or 13 further comprising a scale fixed in relation to the framework, and a flexible measuring band fixed to the means capable of moving the resilient covered roll radially towards and away from the shaping roll in substantive use: the scale having subdivisions corresponding to values of such radial displacement in use and the band having subdivisions relevant to the diameter of a selected shaping roll, whereby preadjustment, by moving both the preadjustment mechanism and the radial-displacement means, can be controlled by the band initial position, and radial displacement in use can be controlled by the band movement along scale divisions.

15. A two-roll sheet-bending or plate-bending machine substantially as herein described with reference to and as illustrated in the accompanying drawings.