NZ239841A - Plate bending machine with pivotable centre punch - Google Patents

Description

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V^3 Patents Form No. 5 / ^ ■V ^ "9 J AN 1992 ^ *- . r ;NEW ZEALAND PATENTS ACT 1953 COMPLETE SPECIFICATION ;PLATE BENDING MACHINE ;WE, LIFT VERKAUFSGERATE-GESELLSCHAFT M.B.H., a company under the laws of Austria of Franzensgasse 25, A-1050 Vienna, AUSTRIA ;hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: ;- 1 - ;(followed by page la) ;2.39841 ;-la- ;PLATE BENDING MACHINE ;FIELD OF THE INVENTION ;The invention relates to a plate or sheet bending machine with three punches or tools the relative movement of which providing the bending operation. ;PRIOR ART ;Conventionally a plate is bent along a straight bending edge in that an upper punch (also called the upper tool) is moved against the plate resting on a lower die or on two lower tools, the upper punch pressing the plate with the area of the bending edge to be shaped into the die or between the two lower tools, so that the plate is bent. It is disadvantageous that generally no precisely defined or sharp bending edges can be formed and that also a considerable part of the energy applied by friction to the die or to the stationary lower punches is lost. ;A bending machine for already profiled plates is also known (WO 81/02535), in order to provide said profiled plates with a corrugation. An upper punch, which can move up and down cooperates with a stationary lower punch, as well as inclined additional punches on either side thereof movable obliquely up and down in the direction of their principal plane. ;Whilst the upper punch with the facing stationary lower punch shapes the corrugation in the plate, the two lateral, sloping punches prepare the next corrugation. For a simple bending of a plate with a sharp bending edge said known bending machine is neither designed, nor suitable. ;/ ;SUMMARY OF THE INVENTION ;The object of the invention is to provide a plate bending machine of the aforementioned type, which permits the bending of plates whilst producing sharp bending edges, which involves relatively low energy expenditure and very low constructional costs, whilst at the same time treating the plate to be bent as carefully as possible. ;Accordingly, the invention provides a plate bending machine comprising a frame, an upper counter punch movable relative to said frame from an upper rest position transversely to the plane of the plate to be bent into a lower operation position and back, and further comprising two lower bending punches opposite to said upper counter punch and mounted to said frame for pivotal movement about an axis generally extending in the plate bending zone, said lower bending punches being coupled to a pivoting mechanism, wherein said upper counter punch, together with a corresponding mounting, is connected to a carrier guided at said frame for upward and downward movement for pivotal movement about a swivel axis generally extending in the plate bending zone. ;Other aspects of the invention will be apparent from the following description. ;With the invention, the aforementioned objectives are advantageously satisfied and as a result of the fact that at least one of the bending punches, or both bending punches during the bending of the plate are pivoted with the plate areas to be bent against one another, not only is a careful, energy-saving bending of the plate made possible, but also, ;as the counter punch can easily be constructed with a sharp lower edge about which the plate can be bent, sharp and clearly defined bending edges can be produced. The construction of the bending machine can be relatively simple and in particular no solid frame is required as is the case with conventional bending presses. It is particularly ;239^1 ;advantageous in this connection if the two bending punches are mounted in the frame so as to pivot in opposite directions about an axis or shaft located in the vicinity of the plate bend. During bending, the movement of the bending punches can be in an equilibrium of forces to the counter punch or to one another, so that on pivoting the bending punches together with the plate portions a balance can be obtained with relatively low forces. ;In view of the aforementioned equilibrium of forces which is to be sought and the minimum loading of the frame, it is particularly advantageous if the bending punches are coupled in their pivoting movement and are symmetrically pivotable. It is also advantageous in this construction that, as will be explained in greater detail hereinafter, a particularly simple drive possibility with a common drive motor for the two bending punches is readily made possible. ;In order to obtain the desired, precisely defined bending edges, particularly in the case of thin plates, it is also favourable if the bending punches are pivotable about a common axis, which is then located in the vicinity of the bending edge to be formed in the plate. In addition, the common axis for the sought purpose of the sharp bending edge is preferably located in the plane of the up and down movement of the counter punch. ;The counter punch can be stopped and locked in its working position moved up to the surface of the plate to be bent and therefore during bending forms a stationary counterpunch about which the plate is bent by means of the bending punches. ;For example to restrain to the greatest possible extent during a multiple bending of a plate an impeding by the upper punch against which then strikes the multiply bent plate, the ;\ ;1991 ;- 4 - ;239g^-l counter punch with its mounting support may be pivoted about an axis parallel to the bending edge in the plate or coinciding therewith. This construction permits a lateral pivoting away of the upper punch in the end phase of the bending process when the multiply bent plate strikes against it. The upper punch can be mounted in freely pivotable manner, or it can be connected to a pivot drive, which is e.g. activated by a microswitch, which is struck by the plate. ;It is favourable for the smooth operation of the bending process and for obtaining the desired sharp bending edges, if the horizontal pivot axis or pin of the counter punch in its operating position at least substantially coincides with the common pivot axis or pin of the bending punches. ;It would be conceivable to equip the counter punch with an eccentric drive, as described in WO 81/02535, but it has been found that in the case of the present bending machine that with the counter punch can be associated a spindle drive for the up and down movement. Such a spindle drive also permits the aforementioned stopping or locking in the working position of the punch, in that the spindle is fixed. ;In order to bring about in a constructionally simple manner the pivoting of the bending punches, it is advantageous that rack and pinion gears are associated as the pivot mechanism with the punches. The rack and pinion gears are preferably symmetrically arranged and in particular coupled to a common drive motor. ;On each bending punch are articulated several racks distributed over the machine width and which in turn mesh with pinions located on a shaft, the bending punches being simultaneously drivable at several points over the machine width. ;"/0cr'99r ;- 5 ;2.398^1 ;To simplify the drive mechanism, it is also advantageous if on the two shafts associated with the two bending punches are located two meshing pinions and consequently one shaft driven by the drive motor drives the other shaft rotating in the opposite direction. ;For a careful treatment of the plate during bending, it is then also advantageous if the bending punches have on their top surfaces freely pivotably mounted pressure members engaging on the plate. It is also advantageous if the pressure members are planar on their top surfaces and are in each case mounted in a partly cylindrical bed provided in the corresponding punch. ;When bending smaller plates and with a view to obtaining the sought sharp, exactly defined bending edges, it can also be favourable if the bending punches are constructed on their top surfaces in cutting edge-like manner with a convex curvature. ;It is also advantageous if the,e.g. sword-shaped counterpunch has a cutting edge-like lower bending edge, e.g. with a convex curvature. ;In order to obtain a counter-balanced synchronous, oppositely directed pivoting of the bending punches about a precisely defined, imaginary pivot axis, it has proved advantageous if the bending punches are coupled to each other by means of some pairs of angle levers to guide their movement during pivoting and which are in turn centrally interconnected by means of a joint. The angle lever pairs are distributed over the machine width. The joints by means of which the angle levers of a pair are interconnected, in particular move in the vertical median plane of the bending machine, in which is also located the said common pivot axis. This median plane o\ ;/ ;i •T'' ;~'0cT/99i- ;2398^1 ;is in particular the plane along which the counter punch is optionally moved up and down. ;A simple and robust construction can be achieved in the case of the latter embodiment in that the angle levers are connected in articulated manner on the one hand to one of the bending punches and on the other hand are displacably guided with a slider or the like in a slide groove of the other lower punch. ;BRIEF DESCRIPTION OF THE DRAWINGS ;The invention is described in greater detail hereinafter relative to preferred, but non-limitative embodiments and the attached drawings, wherein show: ;Fig. 1 A diagrammatic view of a plate bending machine according to the invention in the inoperative position. ;Fig. 2 A corresponding diagrammatic view of a plate bending machine, the opposite side being visible. ;Fig. 3 A diagrammatic view of a plate bending machine corresponding to fig. 1 in a working phase, where plate bending has begun. ;Fig. 4 A corresponding view of the plate bending machine, in which the plate to be bent has already largely been bent. ;Fig. 5 Another representation of this plate bending machine, but at the end of the bending process. ;T £ />;7- ;V ;o^ ;\ - / ;u cT!99i ;7 ;2398^-1 ;Fig. 6 ;Fig. 7 ;Fig. 8 ;Fig. 9 ;Fig.10 & 11 ;Fig. 12 ;Fig. 13 ;Fig. 14 ;A completely diagrammatic, part sectional end view of the essential working parts of the plate bending machine in the inoperative position of fig. 1. ;A corresponding diagrammatic end view of these working parts of the plate bending machine, but at the start of the bending process according to fig. ;2 . ;A corresponding front view of these working parts corresponding to fig. 4 when the bent plate is almost completed. ;A corresponding front view of the working parts of the plate bending machine at the end of the bending process, in a view corresponding to fig. 5. ;Diagrammatic end views of bending tools during the bending of different plate thicknesses and in each case the phase at the start and the end of the bending process are illustrated. ;A diagrammatic end view corresponding to fig. 9 of a bending machine embodiment with modified lower bending punches. ;A diagrammatic partial view of a further modified lower bending punch. ;A diagrammatic cross-section through the upper part of a lower bending punch, e.g. the left-hand punch in fig. 6, along line XIV-XIV in fig. 15, to illustrate the bearing recesses and slide or guide grooves in the bending punch. ;o ;- 8 - ;233^4/ ;Fig. 15 A partial view of the inside of the lower bending punch substantially in the direction of arrow XV in fig. 14. ;Fig. 16 An axonometric representation of a double angle lever arrangement for the articulated connection, mounting and movement guidance of the lower bending punches. ;Fig. 17 A sectional representation similar to fig. 14, but with a double angle lever arrangement along line XVII-XVII in fig. 18. ;Fig. 18 A view, partly in section, along line XVIII in fig. 17 . ;Fig. 19 ;to 21 Sectional representations similar to figs. 14 and 17, but now with two lower bending punches and the double angle lever arrangement to illustrate the different phases during the pivoting of the lower punch. ;DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS ;According to figs. 1 to 5 and 6 to 9 the plate bending machine or bending press 1 has a lower frame 2, on which are provided in frontal main supports 3, 4 vertical guides 5, in which are displaceably guided so as to move vertically up and down columnar supports 6, 7, which carry an upper mounting support 8 with a crossbeam 9, on which is interchangeably fixed an upper, web-like or sword-like punch 10 (also called the upper tool, upper bending tool or upper bending punch). The mounting support 8 for the upper punch 10 is freely pivotably mounted on the supports 6, 7 in conventional swivel iVvn/v;- ;v . *£ 'OCTi99r 'j 2.3 9^41 joints or hinges 11, 12. The function of this swivel or pivoted mounting will be explained hereinafter relative to figs. 5 or 9.

The pivot pin fixed through the pivot or swivel joints 11, 12 of the mounting support 8 to the supports 6, 7 preferably passes along the cutting edge-like, lower bending edge 13 of the upper bending punch 10.

For moving the upper punch 10 up and down e.g. conventional spindle drives are connected to the supports 6, 7, as diagrammatically indicated at 14 in fig. 1. The spindle drives 14 contain spindles 16 driven e.g. by a drive motor 15 optionally via a gear and a not shown clutch or coupling. The spindles cooperate with a spindle nut 17 provided on the underside of the supports 6, 7, in order to move the support 6 or 7 up and down in their guides 5 during the rotation of the spindle 16. These spindle drives 14 and other drive means still to be explained are placed in conventional manner on or in the frame 2.

For bending a plate 18 there are also on the frame 2 two lower, particularly plate-like or web-like bending punches 19, 20 (also called lower tools, lower bending tools or simply lower punches). These two lower bending punches 19, 20 are pivotably mounted on the frame 2 in a manner not shown in figs. 1 to 9, e.g. with the aid of arcuate guides on the main supports 3,4. An example for an arrangement for pivotal movement guidance of the two lower bending punches 19, 20 is explained hereinafter relative to figs. 14 to 21. On the basis of this movement guide the two lower-bending punches 19, 20 are at least substantially pivotable about a common pivot axis 21 (cf. e.g. figs. 7 and 8), which is located in the plate 18 to be bent in the vicinity of the bending edge 22 to be produced and which is in particular located in the plane 23 of the up and down movement of the V , 2.3 9 8^1 upper punch 10. The common pivot axis 21 coincides preferably with the axis defined by the pivot joints 10, 11 for pivoting the upper punch 10, with its mounting support 8 relative to the supports S, 7, when the upper punch 10 is in its working position according to figs. 3 to 5 or 7 to 9, where it serves as a stationary countertool during bending. It is also pointed out in this connection that in the diagrammatic representations according to figs. 6 to 9 and also that of fig. 12, the upwardly and downwardly displaceable supports 6, 7 have been omitted and only the mounting support 8 with the upper punch 10 and the pivot joints 10, 11 are diagrammatically shown. The plane in which the upper punch 10 moves up and down is indicated in figs. 6 to 8 at 23.

The drive for pivoting the lower bending punches 19, 20 about the common pivot axis 21 is a pivoting mechanism, which in the present embodiment contains several rack and pinion gears 24 distributed over the width of the bending machine 1, as shown in figs. 1 to 5. In each case the rack 25 is articulated in the lower area of the in each case lower bending punch 19 or 20, as is diagrammatically indicated at 26 in fig.6. These racks 25 mesh with equally large pinions 29 or 30 located on shafts (indicated in figs. 6 to 9 by their geometrical axes 27 or 28) which are parallel to one another and to the punches 19, 20. One shaft, e.g. 27 is driven by a drive motor, preferably the sole, common drive motor 15, which also drives the spindle drives 14 for the upper punch, as is diagrammatically indicated in fig. 6. It is optionally possible to interpose a gear symbolically designated by the pinion 31 in fig. 6, similar to what is the case with the spindle drive 14 (not shown).

The two shafts 27, 28 extend over the entire width of the bending machine 1 and are rotatably mounted at the front and optionally also at intermediate points between the individual V t i'V c 239 M I rack and pinion gears 25 in corresponding not shown in bearings in the frame 2. There is one rack 25 per rack and pinion gear 24 and one pinion 29 or 30 fitted in non-rotary manner to the corresponding shaft 27 or 28. In the case of rotating the shafts 27, 28, the pinions 25 are consequently linearly displaced and pivot apart the lower bending punches 19, 2 0 connected in an articulated manner thereto in a symmetrical movement in the sense of a spreading apart, cf. particularly fig. 7 (inoperative position) and 8 (pivoted apart working position). To permit the necessary slight pivoting movement of the racks 25 about the shafts 27 or 28, the racks 25 can be received and guided in tube-like casings 32, as is diagrammatically illustrated in fig. 6, the said casing 32 being freely rotatably mounted with flange portions 3 3 on the shaft 27 or 28. The pinions 29, 30 pass through slots in the tubular casings 32 parallel to the longitudinal axis of the rack 25, so as to be able to mesh with the racks 2 5 mounted therein.

A description will now be given of the operation of the plate bending machine 1 by means of the diagrammatic representations of figs. 6 to 9, as well as with reference to figs. 1 to 5 and 10 and 11.

The starting or inoperative position of the plate bending machine 1 is illustrated in figs. 1, 2 and 6. The upper punch 10 assumes its upper inoperative position raised from the plate 18 and in this position a plate 18 to be bent can be supplied manually or mechanically to the bending machine 1 and brought into position thereon. If now a plate bending cycle is commenced, firstly the upper punch 10 with its mounting support 8 is moved downwards with the aid of the supports 6, 7 in the guides 5 until the upper punch 10 contacts with its edge 13 (which is in particular aligned with axis 11, 12) contacts the plate 18 to be bent, which has previously been brought onto the lower bending punches 19, o'~ , -V . 23^3-4 I . This phase in which the plate 18 is fixed between the three punches 10, 19 and 20, but has not yet been bent, is illustrated in figs. 3 and 7, as well as with continuous lines in figs. 10 and 11.

Now, by means of a not shown coupling, the drive to the drive shafts 27, 28 of the rack and pinion gears 24 for the lower bending punches 19, 20 is closed, i.e. engaged. Correspondingly the racks 25 are driven pairwise symmetrically in upwardly sloping manner and pivot in opposite directions the lower punches 19, 20 about their common pivot axis 21, i.e. in accordance with figs 7 and 8 the left-hand bending punch 19 is pivoted clockwise and the right-hand bending punch 20 counterclockwise. With the aid of the pivoting lower tools 19, 20, the plate 18 is symmetrically bent on engaging on the lower edge 13 of the upper punch 10, so as to form the bending edge 22. During this bending process, the upper punch 10 together with its mounting support 8, is fixed or locked in position, e.g. with the aid of the spindle drive 14 (fig. 1), so that it forms a stationary counterpunch during this bending movement. The plate 18 is bent e.g. by approximately 90° along the bending edge 22, cf. figs. 4 and 8. As is also shown in figs 10 and 11, during this bending process an acute bending angle can also be obtained in the plate 18, cf. the dotted line position of the lower bending punches 19,20.

According to figs. 5 and 9, in the case the plate 18 has previously undergone a bending process, the upper punch 10 together with its mounting support 8 can be pivoted to the side about an axis defined by the joints 11, 12 (fig. 1), which in the working position substantially coincides with the bending or pivot axis 21 of the lower punches 19, 20, so as to create space for the already bent edge 34 of the plate 18.

C':- ~'XTl99l! 239S<4l Thus, the bending process is ended and the drives are reversed, so as to pivot back the lower punches 19, 20 into the vertical starting position and to upwardly displace the upper bending punch 10 and straighten it again. The bent plate 18 can now be advanced by one step or can be removed from the machine 1.

As can be gathered from figs.6 to 9 and particularly 10 and 11, the lower, pivotable bending punches can be provided on their upper side in the inoperative position with rod-like, cross-sectionally approximately semi-circular pressure members 35, 36, which are freely pivotably mounted in a semicylindrical bed 37 or 38 (figs. 10 and 11) on the tops of the lower bending punches 19, 20. With this construction with the pivotable pressure members 35, 36 and which have a planar surface 39 facing the plate 18 to be bent, it is possible in simple manner to bring about an adaptation to the particular plate 18, particularly with respect to different plate thicknesses.

However, the lower punches 19, 20 can also be provided with a cutting edge-like top with a convex curvature, as is illustrated at 40 in fig. 12. This embodiment otherwise corresponds to the previously described machine and in particular the representation of fig. 12 corresponds to that of fig. 9, i.e. it illustrates the final state following a bending process with the upper punch pivoted to the side, so that there is no need to provide a further explanation in view of that provided relative to figs. 1 to 5 or 6 to 9.

Fig. 13 is a diagrammatic partial view of another embodiment of the lower bending punches, e.g. the bending punch 19.

Here again on the top of punch 19 is pivotably mounted with its planar top 39 a pressure member 35. For example diagrammatically illustrated frontal pivot pins 41 and a channel-like bearing depression 42 for mounting the prismatic, cross-sectionally approximately^triangular pressure member 35 are provided. > 14 2-39^41 By means of figs.14 to 21 an example will now be given for an arrangement for the mounting, articulated connection and movement guidance of the lower bending punches 19, 20. Figs. 14 and 17 show the upper part of the left-hand lower punch 19 according to fig. 6, but without the pressure member 35 (fig. 6), in a cross-sectional representation. Figs. 15 and 18 show this upper part of the left-hand, lower bending punch 19 in a detail view from the inside, so as to illustrate the shape or profile of the bearing and guidance recesses for the angle levers which are still to be described. However, for the general illustration of this embodiment it is pointed out that figs. 14 and 15 only show the upper part of the lower punch 19, whereas figs. 17 and 18 show the upper part of the lower punch 19 together with a pair of angle levers. This angle lever pair is illustrated alone in a diagrammatic, axonometric view in fig. 16.

As can be gathered from figs. 14, 15, 17 and 18, in each respective lower bending punch, e.g. punch 19, is a blind bore-like bearing recess 4 3 and a through slot-like opening 44 with straight slide grooves 45, so that in elevation (cf. fig. 15) said opening 44 has a cross shape with the slide grooves 45. For the articulated connection of the two lower punches 19, 20 (cf. figs. 19 to 21) there are provided several pairs of double-bent angle levers 46, 47 (cf. also fig. 16), said levers 46, 47 being distributed over the width of the machine 1, as described hereinbefore for the rack and pinion gears 24, and being pivotably interconnected in an angle range at 48. In fig.16, this reference numeral 48 represents a pin for the pivotal connection of the two angle levers 46, 47. Instead of this pin, a through pivot axis may be provided which extends over the entire width of the bending machine according to figs. 1 to 5. f 233I Each lower bending punch, e.g. the punch 19, is connected in an articulated manner with one of the angle levers 46, 47 of such a pair of articulated interconnected angle levers, namely in the zone of its bearing recess 43, in which is articulated one end of an arm 49 of one angle lever, e.g. lever 46 (figs. 14, 17 and 18) with the aid of a pivot pin (or once again a through pivot axis) 50. This lower bending punch, e.g. 19, receives the opposite end of the other angle lever, i.e. here angle lever 47, in displaceable manner in the slide grooves 45 of the through opening 44. For this purpose a pair of sliders 51 can be pivotably fitted to the end of the angle lever 47 and said sliders are guided in linearly displaceable manner in the slide grooves 45, cf. also fig. 16 and in particular figs. 17 and 18. It is pointed out that in fig. 18 the second slider 51 is concealed by the other angle lever 4 6 and is consequently not visible.

Of course, the arrangement with respect to the other lower bending punch 20 is identical, i.e. to said other punch 20 is articulated the angle lever 47, whereas the angle lever 46 is displaceably guided, cf. figs. 19 to 21. Figs. 19 to 21 show the movement sequence when pivoting the lower bending punch 19, 20, if the latter is pivoted by the rack and pinion gear 2 3 as a pivot drive or pivoting mechanism, which is illustrated relative to figs. 6 to 9, but is not shown in figs. 14 to 21. The double lever arrangement or arrangements with angle lever pairs 46, 47 ensure a precise, oppositely directed pivoting movement of the lower bending punches 19, , where horizontal bending force components may be balanced, whilst fixing the exact position of the imaginary pivot axis 21, cf. figs. 20 and 21. Fig. 19 shows the starting or inoperative position, in which the lower punches 19, 20 are positioned with their tops horizontal. In the position according to fig. 20 the lower bending punches 19, 20 have already been pivoted over part of their travel, 239841 whilst in fig. 21 they have e.g. reached their pivoting end position. Pigs. 19 to 21 show that the pivot pin 18 of the angle lever pairs 46, 47 is moved slightly vertically in accordance with the median plane (plane 23 in fig. 6). The sliders 51 during said pivoting movement slide in their slide or control grooves 45, whereas the angle levers 46, 47 are pivoted with their opposite ends relative to the punches 19, With regard to the pivoting mounting of the angle levers 46, 47 in the lower bending punches 19, 20 (joint axis 50), it would also be conceivable to insert not shown bearing blocks in the bearing recesses 43 from the inside or front side (visible in fig. 15), the ends of the angle levers 46, 47 being pivotably mounted in said blocks. These bearing blocks not shown in the drawings can have dimensions precisely corresponding to the bearing recesses 43 and can be secured in the latter with the aid of screws or bolts.

Although the invention has been described hereinbefore relative to embodiments, numerous variants and modifications are possible without leaving the scope of the invention.

Thus, particularly when bending thicker plates, it is also conceivable to pivotably mount the lower bending punches 19, 20 about spaced, parallel axes. Instead of driving the punches 19, 2 0 with the aid of the described rack and pinion gear, this can be brought about with the aid of working cylinders, and it would also be possible to use arcuate racks. The upper punch 19 can e.g. be moved by an eccentric drive or a working cylinder in the up and down direction. Optionally the upper punch 10 can be locked in the lower working position according to figs. 3 or 7 by stopping the eccentric drive in this position. The drive motor 15 can e.g. be an electric motor.

. E A rj \ 23 9 8 4 1

Claims (12)

WHAT WE CLAIM IS:

1. Plate bending machine comprising a frame, an upper counter punch movable relative to said frame from an upper rest position transversely to the plane of the plate to be bent into a lower operation position and back, and further comprising two lower bending punches opposite to said upper counter punch and mounted to said frame for pivotal movement about an axis generally extending in the plate bending zone, said lower bending punches being coupled to a pivoting mechanism, wherein said upper counter punch, together- with a corresponding mounting, is connected to a carrier guided at said frame for upward and downward movement and for pivotal movement about a swivel axis generally extending in the plate bending zone.

2. Bending machine according to claim 1, wherein the horizontal swivel axis of the counter punch in the lower operating position thereof at least substantially coincides with a common pivot axis of the bending punches.

3. Bending machine according to claim 1 or 2, wherein the two lower bending punches are coupled to each other through at least two pairs of angle levers (as hereinbefore defined), which are in turn centrally interconnected via a joint, and ^ •' ! Q which are provided in at least two locations distributed over the width of the machine. : 0 JUL 19^

4. Bending machine according to claim 3, wherein the angle levers are on the one hand connected in articulated manner to one of the lower bending punches and on the other hand are displaceably guided by a slider or the like in a slide groove of the other of the two lower bending punches.

5. Bending machine according to any one of the claims 1 to 4 wherein at least two rack and pinion gears distributed over the width of the machine are associated with each lower bending punch to form said pivoting mechanism, each of the racks being attached to one of the lower bending punches and being driven by the corresponding pinion.

6. Bending machine according to claim 5, wherein the rack and pinion gears are positioned symmetrically in pairs.

7. Bending machine according to claim 5 or 6, wherein the pinion gears of the said rack and pinions are coupled to a common drive motor. 23 9 8 4 1 18

8. Bending machine according to any one of the claims 5 to 7 wherein each lower bending punch is associated with a shaft, and to each lower bending punch are articulated the at least two racks, each of which in turn meshes with its corresponding pinion located on the shaft associated with that lower bending punch.

9. Bending machine according to claim 8, wherein on the two shafts associated with the two bending punches are located two meshing pinions, so that the shaft driven by the drive motor drives the other shaft in the opposite direction.

10. Bending machine as claimed in any one of the preceding claims, substantially as herein described.

11. Bending machine as claimed in claim 1, substantially as herein decribed with reference to any one of the accompanying drawings.

12. A plate when bent using apparatus according to any one of the preceding claims. LIFT,VERKAUFSGERATE- GESELLSCHAFT M.B.H. By ~neys BALDWIN, SON & CAREY