Bending machine and method for bending a sheet metal workpiece

Abstract

The invention relates to a bending machine (1) for bending a sheet metal workpiece (2), comprising at least three bending punches (4,5,6) which respectively have working edges (7,8,9) which are aligned parallel with one another. Relative to an initial plane (3) in which a bend section (10) to be made in the sheet metal workpiece (2) lies, the first and the second bending punch (4,5) are positioned on one side and the third bending punch (6) is positioned on the opposite side of the initial plane (3). The working edge (9) of the third bending punch (6) is displaceable between the working edges (7,8) of the first and second bending punches (4,5). The third bending punch (6) has at least one rotary and one translatory degree of freedom in a reference plane oriented at a right, angle to a working edge (7,8,9). The second bending punch (5) has three degrees of freedom in the reference plane (19).

Claims

1. Bending machine for bending a sheet metal workpiece, comprising at least first, second, and third bending punches, which respectively have first, second, and third working edges which are aligned parallel with one another, wherein relative to an initial plane in which a bend section to be made in the sheet metal workpiece lies, the first and second bending punch are positioned on one side and the third bending punch is positioned on the opposite side of the initial plane, wherein the third working edge is displaceable between the second and the first working edges, wherein the third bending punch has at least one rotary and one translatory degree of freedom in a reference plane oriented at a right angle to at least one of the first and the second working edges, wherein the second bending punch has three degrees of freedom in the reference plane, wherein a supporting body defining the initial plane is provided for the sheet metal workpiece, and wherein the first bending punch has at least one translatory degree of freedom in the reference plane, wherein the bending machine is configured such that during bending operation a first bend leg of the sheet metal workpiece remains horizontal and a second bend leg of the sheet metal workpiece is pushed upwards or downwards, wherein a bend edge divides the sheet metal workpiece within a bend section into the first bend leg and the second bend leg, wherein the first bend leg and the second bend leg are oriented at a bend angle to each other.

2. Bending machine according to claim 1, wherein the third bending punch has three degrees of freedom.

3. Bending machine according to claim 1, wherein the first and the second bending punch can be moved independently of one another.

4. Bending machine according to claim 1, wherein to enable positioning and depending on the number of their degrees of freedom, the first, the second, and the third bending punches are connected to a driving mechanism selected from a group comprising rotary drives, swivel drives, linear actuators or combinations thereof.

5. Bending machine according to claim 4, wherein at least one of the first, the second, and the third bending punches is connected to two driving mechanisms spaced apart from one another in the direction of the first, the second, or the third working edge, respectively.

6. Bending machine according to claim 4, wherein at least one of the first, the second, and the third bending punches is displaceable in the direction of its working edge or is displaceable about a pivot axis parallel with the reference plane.

7. Bending machine according to claim 4, wherein a force measuring element is integrated in at least one of the bending punches and/or in the driving mechanism.

8. Bending machine according to claim 1, wherein at least one of the first, the second, and the third bending punches has two working edges lying approximately opposite one another.

9. Bending machine according to claim 1, wherein at least one of the first, the second, and the third bending punches co-operates with an additional bending punch which is disposed on the opposite side of the initial plane, and wherein the working edges of these two oppositely lying bending punches are directed towards one another.

10. Bending machine according to claim 1, wherein at least one of the first, the second, and the third bending punches has at least one stop face.

11. Method of bending a sheet metal workpiece, the method comprising steps of: providing a bending machine having a first bending punch having a first working edge, a second bending punch having a second working edge, and a third bending punch having a third working edge, the first working edge, the second working edge, and the third working edge being aligned parallel with one another, placing a sheet metal workpiece in an initial plane, such that the first and second bending punch are positioned on one side and the third bending punch is positioned on the opposite side of the initial plane, and performing a bending operation comprising: moving the third working edge between the first and the second working edges in at least one rotary and one translatory direction in a reference plane oriented at a right angle to at least one of the first and second working edges, retaining the sheet metal workpiece between the first working edge and the third working edge essentially in the initial plane so that a first bend leg is formed, wherein the first bend leg remains horizontal, and directing the second working edge along a path about the third working edge so that a bend edge and a second bend leg adjoining the bend edge are formed at the third working edge, wherein the second bend leg is pushed upwards or downwards, wherein the bend edge divides the sheet metal workpiece within a bend section into the first bend leg and the second bend leg, wherein the first bend leg and the second bend leg are oriented at a bend angle to each other.

12. Method according to claim 11, wherein the path of the second working edge is set so that it makes contact with the sheet metal workpiece with as little relative movement as possible during the bending operation.

13. Method according to claim 11, wherein before or during the bending operation, the distance between the first and the second working edges is set and/or adjusted depending on workpiece properties.

14. Method according to claim 11, wherein during the bending operation, the distances between the third and the first working edges and the third and the second working edges may be kept more or less the same size.

15. Method according to claim 11, wherein the first, the second, and the third bending punches are directed onto the workpiece surface oriented essentially at a right angle during the bending operation.

16. Method according to claim 11, wherein in order to bend the sheet metal workpiece in partially opposite directions, the first and/or the second bending punch is or are positioned on one side or on the opposite side of the initial plane if necessary before the respective bending operation.

17. Method according to claim 11, wherein in order to bend the sheet metal workpiece in partially opposite directions, a fourth bending punch is used which is disposed lying opposite one of the three bending punches but only three of the first, the second, the third, and the fourth bending punches are ever in active use during the bending operation.

18. Method according to claim 11, wherein in order to introduce or remove a sheet metal workpiece, at least one of the first, the second, and the third bending punches is removed from the working area in the direction of its working edge or about a pivot axis parallel with the reference plane.

19. Method according to claim 11, wherein a sheet thickness of the sheet metal workpiece and/or a bend angle can be calculated by determining a position of at least one of the first, the second, and the third bending punches and measuring a force applied to the sheet metal workpiece.

Description

(1) To provide a clearer understanding, the invention will be described in more detail below with reference to the appended drawings.

(2) These are highly simplified, schematic diagrams illustrating the following:

(3) FIG. 1 an overall view of a bending machine with three bending punches;

(4) FIG. 2 a perspective view of a section through a bending punch with two working edges lying opposite one another;

(5) FIG. 3 a perspective view of a bending punch with a driving mechanism;

(6) FIG. 4 a combination of options for operating a driving mechanism which guarantees one degree of freedom for a bending punch in a plane;

(7) FIG. 5 a combination of options for operating a driving mechanism which guarantees two degrees of freedom, for a bending punch in a plane;

(8) FIG. 6 a combination of options for operating a driving mechanism which guarantees one degree of freedom for a bending punch;

(9) FIG. 7 an illustration of the sequences of movements of the bending punch during a bending operation;

(10) FIG. 8 an illustration of the sequences of movements of the bending punch during a bending operation in the opposite direction;

(11) FIG. 9 a perspective view of a section of one possible embodiment for operating a bending machine with three bending punches;

(12) FIG. 10 a perspective view of another possible embodiment for operating a bending machine with three bending punches;

(13) FIG. 11 a schematic diagram illustrating possible ways of measuring the sheet thickness and determining the bend angle of a sheet metal workpiece;

(14) FIG. 12 a bending punch, with an integrated stop face

(15) Firstly, it should be pointed out that the same parts described in the different embodiments are denoted by the same reference numbers and the same component names and the disclosures made throughout the description can be transposed in terms of meaning to same parts bearing the same reference numbers or same component names. Furthermore, the positions chosen for the purposes of the description, such as top, bottom, side, etc., relate to the drawing specifically being described and can be transposed in-terms of meaning to a new position when another position is being described.

(16) FIG. 1 is an exemplary diagram, illustrating a section through a bending machine 1 and a sheet metal workpiece to be processed 2, which is oriented in an initial plane 3. The sheet metal workpiece 2 is essentially lying on a first bending punch 4 and on a second bending punch 5. A third bending punch 6 is positioned on the opposite side of the initial plane 3. The three bending punches 4, 5, 6 are in contact with the sheet metal workpiece 2 to be bent essentially at their working edges 7, 8, 9. Lying between the working edges 7 and 8 of the first and second bending punches 4 and 5 is the bend section 10 in which the sheet metal workpiece 2 will essentially be formed. Bending punches 4, 5 act in a manner akin to a die serving as a bottom tool of a bending press and the third bending punch 6 acts in a manner akin to a top tool of a bending press. When all three bending punches 4, 5, 6 are in contact with the sheet metal workpiece 2 to be processed, the highest bending moment is transmitted to the sheet metal workpiece 2 at the bend edge 11. This bend edge 11 is virtually consistent with the third, working edge 9 of the third bending punch 6. The bend edge 11 divides the sheet metal workpiece 2 within the bend section 10 into a first bend leg 12 and a second bend leg 13. During the bending operation, these two head legs 12, 13 are deformed only in their part lying within the bend section 10. As may be seen from this schematic diagram, the sheet metal workpiece 2 to be processed is also lying on a supporting body 14 in addition to the first bending punch 4 and second bending punch 5. The supporting body 14 may be pro vided in the form of a simple supporting table which merely serves to support the sheet metal workpiece 2. This is of particular advantage if the sheet metal workpiece is very large. It is also possible for the supporting body 14 to incorporate a conveyor device 15 which is responsible for manipulating the sheet metal workpiece 2. Such a conveyor device 15 might be a conveyor belt integrated in the supporting body 14, for example, which is used to transport the sheet metal workpiece 2.

(17) For particularly long sheet metal workpieces 2 with long bend legs 12, 13, it would also be conceivable for an additional supporting body 16 to be provided, on which the sheet metal workpiece 2 can lie. Another option is to provide a stop element 17 which can be used to position the sheet metal workpiece 2. This stop element 17 may either be a stand-alone element or may be integrated in a supporting body 14, 16. It would naturally also be possible for the stop element 17 to be used not only for positioning tasks but also to manipulate the sheet at the same time.

(18) By displacing the first bending punch 4 and/or the second bending punch 5, the distance 18 between the two bending punches 4, 5 which essentially defines the bend section 10 can be set. In this respect, it is of advantage if the third bending punch 6 is positioned in such a way between the first bending punch 4 and second bending punch 5 that it lies symmetrically between the two bending punches 4, 5.

(19) FIG. 2 is a perspective view illustrating a bending punch 4, 5, 6, the section representing a reference plane 19. The bending punch 4, 5, 6 illustrated in this view has a working edge 7, 8, 9 at both ends of its vertical extension. This being, the case, it can be used so that it can make contact with the sheet metal workpiece 2 by means of its working edge 7, 8, 9 on either side of the initial plane 3, which means that it does not have to be pivoted in order to be used on the opposite side of the initial plane 3. This means that a bend can easily be made in a sheet metal workpiece 2 in the opposite direction with such a bending punch 4, 5, 6.

(20) FIG. 2 illustrates the possible options for movements, also referred to as degrees of freedom, by which the bending punches 4, 5, 6 can be moved in the reference plane 19. The possible movements are in a horizontal direction 20 corresponding to a guiding direction along the initial plane 3, a vertical direction 21 corresponding to a direction normal to the initial plane 3 and a direction of rotation 22 corresponding to a rotation of the bending punch 4, 5, 6 in the reference plane 19. Due to the combination of guiding options along a horizontal direction 20 and a vertical direction 21, the bending punch 4, 5, 6 is in principle able to reach every point in the reference plane 19. Due to a further option of moving in the direction of rotation 22, not only can every point in the reference plane 19 be reached, the orientation of the bending punch 4, 5, 6 can also be varied at any of these points.

(21) FIG. 3 is a schematic illustration of how a combination of different driving mechanisms 23 can be set up in order to position a bending punch 4, 5, 6 anywhere in the reference plane 19. In order to move a bending punch 4, 5, 6, it is necessary to couple it with a driving mechanism 23. This driving mechanism is responsible for positioning the bending punch 4, 5, 6 in the reference plane 19. Depending on the number der degrees of freedom of a bending punch 4, 5, 6, there are various options in terms of the driving mechanism 23 based on combinations of different rotary drives 24, swivel drives 25 and linear actuators 26.

(22) FIGS. 4a and 4b, as well as FIGS. 5a to 5e illustrate several possible combinations of drives, for moving a bending punch 4, 5, 6 in the reference plane 19.

(23) FIGS. 4a and 4b illustrate the simplest embodiment of a drive combination in which one degree of freedom is provided by one driving mechanism 23. This can be achieved either as illustrated in FIG. 4a by a linear actuator 26 or as illustrated in FIG. 4b by a rotary drive 24 or swivel drive 25. As a result, either the position of a bending punch 4, 5, 6 in one direction can be changed or the position of the bending punch 4, 5, 6 in the reference plane 19 can be changed.

(24) FIG. 5a to FIG. 5e illustrate different arrangements whereby two degrees of freedom to move are imparted, to the bending punch 4, 5, 6, this being achieved by the co-operating drives. Firstly, as illustrated in FIG. 5a, two degrees of freedom can be obtained by a combination of two linear actuators 26 and these need not necessarily be at a right angle to one another. In this instance, the bending punch 4, 5, 6 can be moved into every position in the reference plane 19 but its orientation cannot be changed. Another option is a combination of rotary or swivel drives 24, 25 and a linear actuator 26. In this respect, as viewed from a machine frame, the linear actuator 26 may be connected in front, of the rotary or swivel drive 24, 25 as illustrated in FIG. 5b, or the rotary or swivel drive 24, 25 may be connected in front of the linear actuator as illustrated in FIG. 5c. Another possibility, as illustrated in FIGS. 5d and 5e, is to combine two rotary or swivel drives 24, 25, in which, case they can be installed in different positions of the driving mechanism 23. A combination of these drives also means that either the positioning or the position of the bending punch 4, 5, 6 are not freely selectable.

(25) Based on the examples illustrated here, a combination of driving mechanism, is possible whereby three drives can be used to move the bending punches 4, 5, 6 to any position in the reference plane 19 and orient them. In view of the large number of examples of possible embodiments, these will not all be described and Illustrated in detail because the individual options can be put together in any case by combining the embodiments illustrated as examples in FIGS. 4 and 5.

(26) FIG. 6 is a schematic diagram illustrating a sequence of a bending operation. The sheet metal workpiece 2, having been clamped between the bending punches 4, 5, 6, is bent by the movement of bending punch 5 along a path 27. During die bending operation, the third bending punch 6 may also be tilted in order to achieve an optimum bending result.

(27) The travel path 27 of the second bending punch 5, especially the working edge 7, should be selected so that as far as possible, very little relative movement occurs between the bending punch 5 and sheet metal workpiece 2. Not only is this gentle on the workpiece surface 28, the amount of energy needed for the bending operation can also be minimized. The third bending punch 6 should also be moved with the sheet metal workpiece 2 in such a way that no relative movement occurs between it and the sheet metal workpiece 2. During the bending operation, as illustrated in FIG. 6, the first bend leg 12 remains horizontal and the second bend leg 13 is pushed upwards by the second bending punch 5. The sheet metal workpiece 2 is mainly deformed at the bend edge 11.

(28) FIG. 7 is the same schematic diagram of a bending operation as that shown in FIG. 6 but in this instance, the second bend leg 13 is not bent upwards and instead the second bend leg 13 is bent downwards in the opposite direction. To this end, it is necessary for all three bending punches 4, 5, 6 to be moved respectively to the opposite side of the initial plane. On the second side of the initial plane, the bending punches 4, 5, 6 must then each be pivoted 180° so that their working edges 7, 8, 9 are directed towards the sheet metal workpiece to be processed 2 again. To avoid having to carry out this pivoting operation, it would also be conceivable to use a bending punch such as that illustrated in FIG. 2 having two working edges 7, 8, 9 lying opposite one another.

(29) FIG. 8 is a similar schematic diagram illustrating the layout of bending punches 4, 5, 6, as illustrated in FIG. 6 but in this instance for a bend to be made in the opposite direction where, unlike FIG. 7, the bending punches 4, 5, 6 do not have to be moved to the other side of the initial plane 3 because at least one additional bending punch 29 is provided which is not actively engaged during the bending operation, on one side but is used as a replacement for the respective bending punch 4, 5, 6 for a bending operation on the other side so that the bending punches 4, 5, 6 do not have to be moved to the other side of the reference plane 19, nor does their orientation have to be changed.

(30) FIG. 9 illustrates one possible set-up of such a bending machine with three bending punches. In this instance, the first bending punch 4 and second bending punch 5 are each coupled with a driving mechanism 23 comprising two linear actuators and a swivel drive. By means of this driving mechanism 23, the bending punches 4, 5 can be freely positioned in a certain working area 30 of the bending machine lying within the reference plane 19. The driving mechanism 23 connects bending punches 4, 5 to the machine frame 31. Also connected to the machine frame 31 is a driving mechanism. 23 for the third bending punch 6 comprising a rotary drive and a linear actuator. The third bending punch 6 can therefore be pivoted in terms of its working edge 9 and can also be moved towards the sheet metal workpiece 2 or moved away from it. The bending machine is illustrated in section through the reference plane 19, which is disposed exactly in the middle of the bending machine. The second half of the bending machine, not illustrated, is of a symmetrical design with the half of the bending machine illustrated in FIG. 9. To enable the sheet metal workpiece to be threaded out after a bending operation, it seems to be of practical advantage if the bending punches 4, 5, 6 can respectively be pivoted about a pivot axis 32 out of the working area 30 so that the sheet can be easily removed from the bending machine. This operation of pivoting the bending punches 4, 5, 6 may also be necessary if they have to be positioned on the opposite side of the initial plane 3 for making a bend in the opposite bending direction.

(31) FIG. 10 illustrates the bending machine from FIG. 9 but not in section. The driving mechanisms 23 of the respective bending punches 4, 5, 6 are illustrated on either side of the bending punch 4, 5, 6. The bending punches 4, 5, 6 are attached to these driving mechanisms 23.

(32) FIG. 11 is a schematic diagram in which a force measuring element 33 is attached to the third bending punch 6 and by means of this force measuring element 33 and by determining the position of the bending punch 4, 5, 6, the sheet thickness 34 as well as the bend angle 35 can be determined. The sheet thickness 34 can be determined, by moving all of the bending punches 4, 5, 6 into an upright position. The sheet metal workpiece 2 is then, placed on the first bending punch 4 and second bending punch 5. The third bending punch 6 is then moved downwards until the force measuring element 33 has reflected a value back to the machine controller, recording when the third bending punch 6 made contact with the sheet metal workpiece 2. Since the positions of the individual bending punches 4, 5, 6 are very accurately predefined by the machine controller and can be retrieved at any time, the sheet thickness 34 can be calculated.

(33) The method by which the bend angle is determined is as follows. When the sheet metal workpiece 2 is bent, a plastic as well as an elastic deformation occurs during the bending operation. If the sheet metal workpiece 2 is bent beyond its elastic component, i.e. is bent too far, the sheet metal workpiece 2 rebounds by its elastic component as the bending punches 4,5,6 are retracted. When the force on the force measuring element 33 is zero, the bend angle 35 that will continue to be preserved due to plastic deformation, is reached. Using the geometry and position of the individual bending punches 4, 5, 6, a calculation can then be made back to the resultant bend angle.

(34) The force measuring element 33 may be a piezo-element, for example, which is integrated in the bending punches 4,5,6. However, it may also be connected between the bending punches 4,5,6 and driving mechanisms 23 in order to detect the forces acting on the bending punches 4,5,6.

(35) FIG. 12 illustrates another embodiment of a bending punch 4, 5, 6 in which a stop face 36 is provided in the bending punch 4, 5, 6 against which the sheet metal workpiece 2 may sit.

(36) FIGS. 1-12 illustrate what may be construed as separate and independent embodiments of the bending machine 1, the same reference numbers and component names being used for parts that are the same. The diagrams and description relate to examples of embodiments and examples of arrangements of the bending punches 4, 5, 6. The description of the individual arrangements is based on existing bending presses or folding machines. It should therefore be pointed out that certain components of a bending machine in which, the bending punches 4, 5, 6 are integrated, for example press beams or a control unit, are not explicitly described because these are generally known components which are naturally used in this bending machine.

(37) The embodiments illustrated as examples represent possible variants of the bending machine 1, and it should be pointed out at this stage that the invention is not specifically limited to the variants specifically illustrated, and instead the individual variants may be used in different combination s with one another and these possible variations lie within the reach of the person skilled in this technical field given the disclosed technical teaching.

(38) Furthermore, individual features or combinations of features from the different embodiments described and illustrated as examples may be construed as independent and inventive solutions.

(39) The objective underlying the independent inventive solutions may be found in the description.

(40) All the figures relating to ranges of values in the description, should be construed as meaning that they include any and all part-ranges, in which case, for example, the range of 1 to 10 should be understood as including all part-ranges starting from the lower limit of 1 to the upper limit of 10, i.e. all part-ranges starting with a lower limit of 1 or more and ending with an upper limit of 10 or less, e.g. 1 to 1.7, or 3.2 to 8.1 or 5.5 to 10.

(41) For the sake of good order, finally, it should be pointed out that, in order to provide a clearer understanding of the structure of the bending machine 1, it and its constituent parts are illustrated to a certain extent out of scale and/or on an enlarged scale and/or on a reduced scale.

LIST OF REFERENCE NUMBERS

(42) 1 Bending machine 2 Sheet metal workpiece 3 Initial plane 4 First bending punch 5 Second bending punch 6 Third bending punch 7 First working edge 8 Second working edge 9 Third working edge 10 Bend section 11 Bend edge 12 First bend leg 13 Second bend leg 14 Supporting body 15 Conveyor device 16 Other supporting body 17 Stop element 18 Distance 19 Reference plane 20 Horizontal direction 21 Vertical direction 22 Direction of rotation 23 Driving mechanism 24 Rotary drive 25 Swivel drive 26 Linear actuator 27 Path 28 Workpiece surface 29 Additional bending punch 30 Working area 31 Machine frame 32 Pivot axis 33 Force measuring element 34 Sheet thickness 35 Bend angle 36 Stop face