A sheet workpiece bending machine

(42) Date of commencement of the patent: 15. 5. 1996 (45) Date of issue: 27.12.1996 (30) Priority:

29.12.1988 IT 68166 A / 88 claims. (56) Documents:

DE 3011665A1 DE 3245755A1 EP 0051554A2 (54) BLECH BENDING MACHINE (73)

Patentee:

AMADA COMPANY, LIMITED KANAGAWA-KEN (JP).

(72) Inventor:

CATTI ALBERTO AIMONE TURIN (IT).

SARTORIO FRANCO TURIN (IT).

VERGANO STEFANO TURIN (IT).

CD

AT 401 897 (57) A plate bending machine comprises upper and lower bending tools (26, 28) of long, slim figure, which are movable relative to each other and away from each other, for bending a piece of sheet metal inserted between them, at least three frames (12, 14), each of which lies in one of three normal planes to the longitudinal direction of the bending tools (26, 28), the frames (12, 14) holding the upper and lower bending tools (26, 28) in a manner via skirt parts, that the bending tools are movable relative to each other towards and away from each other, one each mounted on each frame (12,14) device (40,42) for applying a driving force, seen in the longitudinal direction of the upper and lower bending tools (26,28), at least three sections, to move the upper and lower tools toward and away from each other relative to each other, and a controller (E) for controlling the driving force applying device (40, 42), so that the distances between the upper and lower tools (26,28), at least at the three sections of the bending tools, be kept the same during the actual bending process.

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WR 0078319

AT 401 897 B

The invention relates to a sheet metal bending machine, comprising upper and lower bending tools of long, slim figure, which are movable relative to each other and away from each other, for bending a piece of sheet metal inserted between them, at least three frames, each of which lies in one of three planes normal to the longitudinal direction of the bending tools, wherein the frames hold the upper and lower bending tools in a manner via skirt parts, that the bending tools are movable relative to each other towards and away from each other, depending on a mounted on each frame device for applying a driving force, seen in the longitudinal direction of the upper and lower bending tools, at least three sections, to move the upper and lower tools toward and away from each other relative to each other, and a controller for controlling the driving force applying device, wherein the controller has detecting means provided corresponding to each frame for setting the distance between the upper and lower bending tools at the three portions thereof and a signal processing means for outputting a control signal to the driving force applying means in accordance with a signal from the distance detecting means; so that the distances between the upper and lower tools are kept the same at least at the three sections of the bending tools during the actual bending process.

In sheet metal bending machines, the upper punch and lower punch (upper and lower bending tools) are held by supports (skirts), which are usually narrow but very deep, so that they can withstand deflection under the bending load encountered in machines of a length of two oil dynamic cylinders, which are located at the ends of the movable support. The flexural rigidity of the beam is very important because deflection affects a difference in the distance between the punch and die in the middle area from the side portions of the beam. Even with limited deflection, this causes a bending or bending of the sheet by an angle that is not constant along the bending edge.

In very long press brakes for bending sheet metal workpieces several meters long, the depth of the beam reaches high values, on the order of 2 meters or more. In fact, as the length of the beam increases, its moment of inertia for a given mid-range deflection must increase with the cube of the length of the beam.

This means that the machine gets very high. In a vertical machine of the most common type, the considerable depth of the lower beam requires, among other things, the formation of a pit in the workshop floor to accommodate the volume of this beam and maintain the working plane in an ergonomically favorable position.

The DE-30 11 665 A1 is shown in a sheet metal edge-bending press, wherein each cell comprises two side stand, a bending cheek and a hydraulic cylinder. According to this DE-OS 30 11 665 a plurality of such cells should be able to be combined to form an overall machine.

EP-0 051 554 A2 discloses a tube bending press for bending rectilinear tube blanks into a curved cross section. In the control circuit, a first sensor is arranged between two sections and checks the aligned position of these sections. At the same time a pump is controlled by a first control unit to the aligned position between the sections or Also, the end portion is maintained in alignment with the main portions via a further sensor and a second control means responsive to the sensor for actuating another pump. In this arrangement, the sensors merely monitor the aligned position between the individual elements, controlling respective associated pumps via respective control means. Therefore, if the member serving as a reference member is deformed due to a large load during the actual bending operation, the adjacent members are also readjusted depending on the deformed position of the reference member.

A sheet metal bending machine of the type mentioned is further example, DE-32 45 755 A1 refer to, is aimed at an automatic adjustment of the bending line of the bending tool.

In view of the known prior art, it is therefore a principal object of the present invention to provide a plate bending machine for bending long workpieces of sheet metal, which allows a very accurate bending, but in which the support (the skirt) is not as deep as in machines the state of the art.

Another object of the invention is to provide a sheet metal bending machine which can operate with higher bending forces than this^-was conventional in the art, but the deflection of the carrier is equal to or preferably smaller than the deflection to which the carriers of prior art presses were subjected.

To solve this problem, the sheet metal bending machine according to the invention, starting from the above-mentioned prior art essentially characterized in that the device for

AT 401 897 Β

Applying the driving force, which is arranged on intermediate frame, with both end portions of adjacent, movable skirt parts cooperates and at the same time exerts a driving force on the adjacent, movable skirt parts. Thus, in addition to an automatic adjustment of the bending line of the bending tool can ensure that the adjacent end portions of adjacent, movable skirt parts are aligned in the longitudinal direction of the bending tools in alignment with each other. According to the invention, it is thus ensured that even in the event that the upper and lower bending tools are subject to deformation due to excessive loads during the actual bending operation, nevertheless precise bending operations can be performed according to the specifications.

According to a modified embodiment, a sheet metal bending machine, comprising a first frame, upper and lower bending tools of long, slim figure, each of which is held over skirt parts on the first frame, wherein the bending tools are movable relative to each other towards and away from one another for bending a sheet metal workpiece inserted between them, a second frame, which lies in a plane parallel to the first frame, and a device for moving the bending tools relative to and away from each other, essentially characterized that the second frame is truncated on a skirt part fastened to the first frame and is rotatable about an axis parallel to the longitudinal direction of the bending tools, and in that the device for moving a first drive, which is attached to the first frame, to move the upper and lower bending tools toward and away from each other, when a distance between the upper and lower bending tools is relatively large, and a second drive, which is attached to the second frame, to apply a driving force to the upper bending tools or to the lower bending tools, to move the upper and lower tools toward and away from each other relative to each other, when an actual bending operation is performed. Thus, a coarse adjustment of the distance between the individual bending tools can be made in a simple manner, while for the actual bending operation, the movement of the bending tools takes place realtiv each other via a second drive, with which the corresponding exact movements that are required for the bending process, can be performed ,

Furthermore, another modified embodiment of a sheet metal bending machine according to the invention, comprising a first frame, upper and lower bending tools of long, slim figure, each of which is held over skirt parts on the first frame, wherein the bending tools are movable relative to each other towards and away from one another for bending a sheet metal workpiece inserted between them, at least three second frames, each of which lies in one of three planes normal to the longitudinal direction of the bending tools, on each of the second frame mounted devices for applying a driving force, seen in the longitudinal direction of the bending tools, at least three sections, to move the upper and lower tools toward and away from each other relative to each other, and a controller for controlling the driving force applying device, essentially characterized that the controller has detectors for detecting the distance between the upper and lower bending tools at the three sections and controls the devices for applying a driving force in response to signals from the detectors for detecting the distance, so that the distances between the upper and lower tools are kept the same at least at the three sections of the bending tools during the bending process.

The invention is explained in more detail below with reference to non-limiting examples illustrated in the drawing. It shows: Fig. 1 A, B, C are schematic illustrations of the principle of the invention; FIG. 2 a shortened perspective view of an embodiment of a press according to the invention or Plate bending machine, wherein also the control processor is indicated schematically; FIG. 3 a schematic front view of the machine, also shortened; FIG. 4 a schematic cross section of the machine according to the vertical plane of the machine IV-IV in Fig. 3, wherein a detail of a variant is shown; FIG. 5 a partial view of one of the servo motor units of FIG. 2 on a larger scale; FIG. 6 a plan view of a press brake according to another embodiment of the invention; FIG. 7 a cross section along the vertical plane VII-VII in Fig. 6 on a larger scale; FIG. 8th a partial front view in the direction of arrow VIII in Fig. 6 and FIG. 9 a schematic front view in the direction of arrow IX in Fig. 7th

First, the principle forming the basis of the present invention will be explained with reference to Figs. 1A, 1B and 1C.

The deflection F of the skirt portion of a wearer is given by the following formula:

F = KoPL³/ l

Where F is the deflection of the beam, P the total load of the beam, L the length of the beam, I

AT 401 897 Β mean the moment of inertia of the carrier and Ko a constant.

If the carrier has a prismatic cross section, then I = BH³/ 12, so that F = Ki PL³/H³ where B is the width of the beam, H is the depth of the beam, and Ki is a constant.

Obviously, given a deflection F and width B of the beam, the depth H of the beam is proportional to L. Therefore:

1) in the case of a press brake (FIG. 1A) with a certain length L, a total load P and a certain deflection F of the carrier with a depth H is a same deflection F (FIG. 1B) with a half depth H / 2 carrier achievable when an additional load P is applied in the center of the machine and the lower and upper beams are each subdivided into two independent beams of length L / 2;

2) the load can be further increased to 4P (Fig. 1C) and the height of the carriers can be halved again (H / 4), if a further subdivision is carried out in two halves, etc., with further halving.

Thus, a considerable length press brake can be manufactured by aligning modular elements, which are much smaller in terms of the dimensions of the carrier and the applied force, provided that the ends of all the individual modules are moved simultaneously with the highest accuracy.

According to the invention, this accuracy is achieved by the presence of a control processor which provides for the simultaneous movement of all support members for the movable supports, ie the end supports and the intermediate support or supports, preferably with numerical control, so that the microshifts 5s of all the supports and the corresponding parts of the carrier are identical to each other and all take place at the same time 5t.

This type of control is an electronic technique known by various names (electric wave or linear interpolation of movement of different axes). As far as known to date, this technique has been used in known press brakes only for the control of two oil-dynamic or electrically controlled servo cylinders, which are provided at the ends of an undivided movable support.

According to the invention, a movable support need not even be physically divided, but may consist of a continuous support connected to each support member. In this case, the carrier and the support members form a statically indeterminate system.

However, if, as is preferred, at least the movable support is physically divided into successive separate modules, the or each intermediate support part of the support is simultaneously coupled to successive modules. In this case, each module and its supporting parts form an isostatic system.

The carrier opposite the movable carrier is generally the lower carrier. It is favorable that this carrier, when it is stationary or substantially stationary, as is often the case, is also subdivided, at least as regards its action, as the movable carrier, with its supporting parts, which act as reactants, stationary are arranged and the stationary arranged carrier in any case has a reduced depth. This feature offers the great advantage that the formation of a pit in the workshop floor for the accommodation of the volume of the lower carrier is unnecessary.

According to FIGS. 2 4, a press brake has a frame generally indicated at 10. According to the invention, the frame 10 consists essentially of a series of more than two vertical C-shaped steel structures. The end constructions (support frame) are denoted by 12 and the intermediate constructions (support frame) by 14. The structures 12, 14 are rigidly connected to each other, inter alia, by a longitudinally extending base part 16, which acts as a stiffening element.

The C-shaped constructions 12, 14 hold an upper support (skirt) 18 serving as a tool holder and a lower support (skirt part) 20 serving as a tool holder. These two supports 18, 20 lie in a common vertical plane.

Figures 2 to 4 show the most common arrangement in which the lower support 20 is stationarily arranged and the upper support 28 is vertically movable in the general plane.

According to the invention, both the upper support 18 and the lower support 20 are or at least the movable support of the two is subdivided into a number of n sections or modules. It will be understood that to be effective, the number must be n £ 2. In other words, the frame 10 must have at least one intermediate structure such as 14 for realizing the invention.

The portions or modules of the upper beam 18 are denoted by 22 and those of the lower beam 20 by 24. The length L of each section 22 and 24 (Figure 3) is an integer fraction of length nL

AT 401 897 Β of the corresponding carrier 18, 20.

The lengths L also determine the distance between the constructions 12, 14.

At the bottom and over the entire length, the upper support 18 carries a corresponding row of V-shaped bending dies (upper bending tools) 26. The lower support 20 carries at the upper side and along its entire length a corresponding row of V-shaped bending dies or lower dies (lower bending tools). 28, which cooperate with the stamp 26.

Each section 22 of the upper beam 18 has end portions 30 (FIG. 3) which have a recess towards the punch 26. The lines or zones of separation or transition between one section 24 and the next are indicated at 36.

Each transition zone 32 and 36 lies in the midplane of one of the constructions 12, 14.

The end portions 34 of the modules 24 rest directly upon rigid reaction posts formed by the lower legs 38 of the C-shaped structures 12,14. It is clear that each module 24 is isostatically supported on two supports like a support. -

The C-shaped constructions 12, 14 of the frame 10 carry motor drives for moving the movable support 18. According to the invention, these drives are constituted by n + 1 servomotor units, one of which will be described with reference to FIG.

The end servomotor units are designated 40 and the intervening units 42.

The servomotor units 40 serve exclusively for raising and lowering the end modules 21, while the units 42 serve for raising and lowering respectively two adjacent modules 22.

If the total compressive force which all servomotors must exert on the movable support 18 to effect bending is designated P, then the units 40 are dimensioned to exert a downward compressive force of P / 2 (n-1) while the intervening units are dimensioned to exert a downward compressive force of twice the value P / (n-1).

As shown in FIG. 5 As can be seen, each servomotor unit 42 (and each unit 40) includes a numerically controlled electric motor 44 attached to the associated C-shaped structure 14 (or 12). The shaft of the motor 44 carries a pinion 46 which drives (for example) a driven gear 50 via a toothed belt 48. The driven gear 50 is keyed on a screw spindle 52 whose vertical axis lies in the median plane of the associated structure 14 (or 12). The spindle 52 is mounted in bearings 14 attached to the structure 14 (or 12).

With the spindle 52, a ring nut 56 cooperates, which forms part of a robust, movable element 58. The element 58 has a lower support part 60 which surrounds the recessed parts 30 of two adjacent modules 22 (or only the end part 30 in the case of an end unit 22).

It will be understood that each module 22 is isostatically mounted in the manner of a carrier on two supports, the supports being formed by the components 60.

As shown in Figure 4, in alignment with each C-shaped construction 14 (and 12), a C-shaped auxiliary structure 62 is provided within the C-shaped recess of the structure and has a lower leg connected to one of the ends of one of the modules 24 of the lower carrier 20 is connected, and an upper leg, which carries a detector element of a position transducer. This detector element 64 is preferably an optoelectronic reader.

On the carrier 18 in accordance with each support 60, a reference element in the form of a vertical optical line 66 is attached.

The readers 64 are also shown in FIG. As can be seen, these are connected to an equal number of inputs of an electronic processor E. The processor E processes the position signals supplied to it by the readers 64 and provides numerical control output signals to all servomotors 44.

As already mentioned in the introduction, the processor E behaves like a so-called electric wave and performs a linear interpolation of the movement of the various devices 58 so that the vertical microshifts 5I of all the devices 58 and all ends 30 of the modules 22 are identical to one another Time 5t take place. The servo system with the transducers 64-66, the processor E and the servomotors 44 are independent of the deformations of the constructions 12, 14 thanks to the mounting of the detectors 64 on the auxiliary structures 62 which are independent of the constructions 12, 14 of the frame 10 are not affected.

It is clear that with a solution such as shown in Figs. 2 to 5, press brakes of considerable length and high overall loading using shallow depth supports and supports capable of exerting forces which are only a fraction of the total load, can be produced. It is also clear that presses of this type do not support the formation of pits in the

AT 401 897 Β

Workshop floor required because the depth of the lower beam 20 is limited.

In practice, it is possible to produce a press whose lower support of limited depth, as in 20, is continuous, ie it is only effectively divided into sections, such as 24. This support differs from a modular fixed support only in that there are more than two constructions for connection to the upper beam, and therefore may have a smaller depth than would be required for a beam supported only at its ends. In this case, the longitudinal member 16 contributes to the continuous lower support to the rigidity of the arrangement or may be omitted altogether.

An upper support, such as 18, may also be a single continuous support which is as long as the machine and has a smaller depth than a support on only two end supports. Also in this case, the continuous beam will behave statically indefinitely as compared with a modular upper beam operatively divided into sections, being provided with a plurality of pillars, such as 60.

In the case of a continuous movable upper beam, it is necessary to equip each of the C-shaped structures, such as 12 and 14, with another auxiliary detection means. One of these devices is shown in FIG. 4 indicated schematically at 70. It is C-shaped with a lower leg 72 fixed to the lower leg of the structure 14 (or 12) and an upper leg 74 carrying a transducer 76 connected to an associated input of the processor E (not shown). The transducer 76 measures the strain occurring deformations of the associated C-shaped structure 14 (or 12). In the case of the statically indeterminate system of the continuous upper beam, this measurement is essential for identifying the O position for the servo system of each of the C-shaped constructions 12 and 14 when the upper punches 26 and lower punches 28 are in contact with each other. In fact, in this case, the O position need not only coincide with the state in which upper punch and lower punch (without inserted plate) are in contact with each other, but this O position must also be a load (ie a deformation) which must be identical for all intermediate sections and at the end sections must correspond to one-half of the load of the intermediate sections of the same load.

Hereinafter, another embodiment of the invention will be explained with reference to FIGS. 6 to 9.

The embodiment illustrated in Figures 6 to 9 has certain features which are the subject of another patent application (A 2971/89) filed simultaneously by the Applicant of the present application, in particular the approach and the bending stages being controlled by different mechanisms.

The press brake has a pair of C-shaped construction parts (first support frame) 100. A stationary support (stationary skirt member) 102 supporting a lower punch (lower bending tool) 104 is fixed to the lower leg of the structural member 100.

A movable upper support (movable skirt member) 106 holding the upper punch (upper bending tool) 108 is guided exclusively on the upper legs of the structural member 100. In the present case, it is assumed that the two carriers 102 and 106 are continuous carriers, although modular carriers would be applicable as shown in FIGS. 1 and 2.

As shown in Figures 6 and 8, the top of each structural member 100 carries a double-acting hydraulic or pneumatic actuator 112 with a vertical axis and all or nothing mode of operation. A lower rod 114 of each actuator 112 carries a support 116 on which the movable support 106 is suspended.

The two actuators 112, each for a structural member 100, are uniformly actuated to effect the return stroke of the upper punch 108 for a bending operation to the lower punch 104 toward and away from the bending operation.

After execution of the Zustellhubes the support 116 abuts against an end stop 118, which can yield against the force of a spring 120. The spring 120 is biased so that the weight of the entire movable mass of the carrier 106 is held.

Further, the press has a plurality (n + 1) of at least three equally spaced C-shaped members (second support members) 122, which are used only in the bending stage according to the principles described and illustrated in the aforementioned patent application.

Each of these C-shaped structural members 122 is arranged isostatically, for example, on a horizontal pivot 124 secured to the lower support 102, as shown. If desired, the C-shaped structural members 122 may be attached to the lower support 102 so as to be freely rotatable about the horizontal pivot 124. The weight is balanced by an associated spring 126, so that the upper leg of the structural part 122 is held in contact with the movable upper support 106 via a roller 128.

AT 401 897 Β

The upper leg of each C-shaped structural member 122 carries a generally designated 130

Reaction unit. The reaction unit 130 comprises a hydraulic or pneumatic actuator 138 of the all-or-nothing mode with horizontal piston rod 134 carrying a reaction bar 136.

In connection with each reaction bar 136, the movable carrier 106 carries a servomotor unit which will be described with reference to FIG.

In Figure 7, the position of a servomotor unit 140 (or 138) at the end of the Zustellhubes is shown by solid lines and in the position at the end of the return stroke in dashed lines.

Each servomotor unit 140 (and 138) has a domed cap 142 at the top

Servomotor unit 140 has reached the end of the feed stroke, the reaction bar 136 is advanced to the position shown in Figure 7, to prevent lifting of the servo motor unit and the carrier 106.

As shown in FIG. 9, each servomotor unit 140 (and 138) has a lower block or support member 144 attached to the upper surface of the movable support 106 in conformity with one of the structural members 122. This block 144 has an upper wedge surface 146, which is designed as a roller table. Another block 148, of which the cap 142 forms part, is vertically slidably mounted in vertical guides 150 which are also mounted on the movable support 106. The block 148 has an inclined wedge surface 152 facing the surface 146 and is also formed as a roller table.

Between the two wedge surfaces 146 and 152, a corresponding wedge 154 is arranged. The wedge 154 is connected to an actuating rod 156 formed as a threaded spindle.

The threaded spindle cooperates with a ring nut 158, which is rotatably mounted in bearings 160, which are arranged in a support 162 which is connected to the upper side of the movable support 106.

Furthermore, a numerically controlled electric servo motor 164 is mounted on the movable support 106, which rotates the ring nut 158 ​​via a drive connection 166, for example a toothed belt.

Once the movable carrier 106 has completed its feed stroke by driving through the components 112, 114 and 146, as in the case of the aforementioned patent application, the servomotor 164 associated with each C-shaped structural member 122 is actuated to insert the wedge 154 between the two wedge surfaces 146 and 152 , whereby the bending stroke is carried out.

In kinematic terms, as in the embodiment of FIGS. 2 to 5 all servomotor units are substantially identical and the only difference is that the servomotors of the units 138 arranged at the ends of the carrier are designed to exert a compressive force P / [n (n-1)], where n is the number of C shaped structural members 122 means, whereas the servomotors of the units 140 for applying a compressive force P / (n-1) associated with the intermediate structural members 122 are formed on the movable support 106.

In the embodiment according to FIGS. 7 to 9, furthermore, each C-shaped structural part 122 is equipped with C-shaped auxiliary detector devices 170 and 172. The device 170 measures the relative displacement between the punch and the lower punch and has a lower leg 174 connected to the lower carrier 102 and an upper leg 176 which carries an optoelectronic transducer 178 cooperating with an optical line 180.

The other auxiliary device 172 measures the deformation of the structural member 122 and is required because in the present case the movable support 106 is a continuous beam. This device 172 has a lower leg 180 connected to the lower leg of the C-shaped structural part 122 and an upper leg 182 which carries a transducer 184 for detecting the deformation of the structural part 122 and detects the zero position when the upper punch 108 and the lower dies 104 are in contact with each other to notify the servo system of each of the C-shaped structural parts 122.