The invention concerns a bending tool for bending electrical pin contacts, with a bending side for transmitting a bending force to at least one pin contact.

The invention also concerns a bending device for bending electrical pin contacts. The invention also concerns a method for bending ΘlΘCtrical pin contacts, wherein a bending tool is moved relative to a pin contact, and at a contact point with the pin contact, a bending force is introduced into the pin contact. Bending tools, devices and methods of the above-mentioned kind are known in the prior art. Using them, for instance, pin or plug-in contacts are bent into plug-in connectors, so that they can be inserted into printed circuit boards with a bent section. In the printed circuit boards, the pin contacts contact tracks. To improve the electrical contact between the pin contacts and the tracks, and to favour the preconditions for soldering the pin contacts and the tracks or corresponding connection points in the printed circuit board, the pin contacts are usually plated with tin or other platings (e.g., in particular, nickel in the case of press-in contacts).

In the case of bending devices, bending tools and bending methods according to the prior art, it is disadvantageous that the bending sides rub on the pin contacts, and this can result in damage to the surface of the pin contacts and the applied plating. Because of the damage, abraded material can be detached from the pin contacts or their tin or other plating. Flaking of the plating can also occur. If particles, and in particular parts of the plating, are detached from the pin contacts, they can cause short circuits in the electrical systems and plug-in connectors into which the pin contacts are built. The short circuits cause failures in the electrical systems and components in which the plug-in connectors are used. These failures are dangerous and expensive. They are dangerous because they can cause malfunctions of the electrical systems, and consequently dangers for people, machines and the environment. The short circuits are expensive because the causes are difficult to determine, i.e. the metallic particles resulting from the abrasion are difficult to find, so that repair of the affected electrical system is expensive. The short circuits can also appear as timing faults, which make searching for the fault difficult. If the cause of the fault cannot be clearly determined, the components which are affected by the short circuit may have to be completely replaced.

Consequently, the invention is based on the object of making gentle bending of the pin contacts possible, and avoiding damage to and abrasion of the surface of the pin contacts, using the above-mentioned bending tool, bending device and bending method.

According to the invention, in the case of the above-mentioned bending tool this object is achieved by the bending side being received movably on the bending tool.

In the case of an above-mentioned bending device, the object is achieved by the bending device having a bending tool according to the invention. In a method for bending electrical pin contacts of the above-mentioned kind, the object is achieved by the relative movements between the bending tool and the pin contact in the contact point being at least partly compensated for by a movement of the bending side relative to the bending tool.

Compared with the prior art, these solutions have the advantage that rubbing movements of a surface of the bending tool or its bending side along the surface of the pin contacts are avoided. Optimally, the bending side and the pin contact have a linear contact at the contact point, which does not move during the bending process. Thus the bending side does not rub on the pin contact, and can generate no abrasion from the pin contact or its tin plating. Avoiding or reducing abrasion prevents or reduces the danger of short circuits in electrical systems into which the bent pin contacts are built. The solutions according to the invention can be combined and further improved as required with the following further embodiments, which are each advantageous in themselves:

Thus according to a first possible advantageous embodiment of a bending tool according to the invention, it can be provided that the bending side is rotatably received on the bending tool. The rotational movement is specially suitable for forming the bending side around a fixed axis so that it can move in a movement plane in which the bending tool is moved. The bending side rolls up positively in the bending tool, and optimally there are no relative movements between the bending side and the pin contact.

According to a further possible advantageous embodiment, it can be provided that the bending side has a round cross-section at least in sections. Along the round cross-section, the bending side can roll up, gently and essentially slip-free, on the surface of the pin contact, in particular if relative movements between the bending side and the surface cannot be completely avoided.

According to a further advantageous possible embodiment of a bending tool according to the invention, it can be provided that bending positions for the pin contacts are predetermined by position- determining elements which are arranged between a plurality thereof along the bending side at a distance from each other and extend essentially perpendicularly away from the bending side. The position- determining elements form indentations between them, and laterally delimit the bending positions in which the pin contacts are guided during the bending. Thus a transverse movement of the pin contacts and rubbing of the pin contacts transversely to the movement or rotation of the bending side is avoided, and the pin contacts are precisely guided and bent.

According to a further advantageous possible embodiment of a bending tool according to the invention, it can be provided that the bending side is formed on a bending edge which is fixed as a separate component on the bending tool. This opens up multiple possibilities for forming the bending side. Thus the bending side, or the component in the form of the bending edge, can be formed to correspond to the appropriate requirements, and made of an advantageous material.

According to a further possible advantageous embodiment of the bending tool, the bending edge can be, for example, a carbide rod, or consist of carbide at least in sections. Carbide encourages rolling up the bending side on the pin contact, because the carbide causes less friction because of its hardness and surface density. The carbide is also more durable than the feature which forms the other sections of the bending tool, and suitable for lasting use of the bending tool. The carbide rod in the form of a bending edge can also be easily exchanged if it is damaged and no longer suitable for a proper bending process. According to a further possible advantageous embodiment of the bending tool according to the invention, it can be provided that the bending edge is inserted into a receptacle which is arranged a marginal area of the bending tool. In the marginal area, the bending edge can simply be fixed in an exposed position on the bending tool. Thus, for example, the bending edge can be inserted into the receptacle in a transverse direction of the bending tool, ensuring that the bending edge is held and supported in the lateral and vertical directions, which form the working directions of the bending tool.

According to a further possible advantageous embodiment of a bending tool according to the invention, it can be provided that the receptacle is formed of at least one fitting element, which holds the bending edge so that it can rotate around a longitudinal axis of the bending edge, and secures it against slipping in the transverse direction. An outer contour of the bending edge can be fitted precisely to the fitting element, and the bending edge can thus easily be inserted into the bending tool.

According to a further possible advantageous embodiment of a bending tool according to the invention, it can be provided that the position-determining elements are of eyelet-like form, and the bending edge runs through openings of the position-determining elements. Thus the bending edge and the bending side formed on it can rotate in the position-determining elements.

According to a further advantageous embodiment of a tool according to the invention, the rotation of the bending edge is made easier, in particular, by the bending edge having a circular cross-section. For example, a radius of the bending edge can be 0.75 millimetres or in a range between 0.5 and 2.0 millimetres. Correspondingly, the bending edge can be used for relatively small and narrow pin contacts. In the case of larger pin contacts, rotation of the bending edge can easily be made possible by putting it into ball bearings or roller bearings, but implementation of these is possible only with difficulty given the existing small diameters of the bending edge or carbide rod.

According to a further advantageous embodiment of a bending tool according to the invention, the friction between the bending side and the pin contact can be further reduced by the bending side being provided at least in sections with a sliding plating. The sliding plating can have the advantageous properly of a Vickers hardness of 2,000 to 3,500 HV. The sliding plating encourages easy, gentle rolling up of the bending edge in the bending tool and on the pin contact.

In the case of a bending device of the above-mentioned kind according to the invention, the above- mentioned task can be achieved better, according to a further possible embodiment, if a tool carrier for the bending tool is movably supported on a bearing element via a supporting element in a guide, a guide angle of the guide being in adjustable form. Thus a movement curve of the bending side can be optimally adjusted to a bending radius of a bent or curved section of the pin contacts, and friction between the bending side and the pin contacts can be avoided. In contrast, in the prior art only fixed, straight-line guides with a gradient of 55° are known. According to a further possible embodiment of a bending device according to the invention, the alignment of the bending side relative to the pin contact can be improved by a guide line which is predetermined by the guide having at least one curved section. By using the curved section, a longitudinal axis of the bending tool can be tilted during the bending process in such a way that the bending side is always aligned optimally to the surface or to a bending radius of the pin contact in its curved section, and sliding and rubbing movements between the bending side and the surface of the pin contact are avoided. Below, the invention is explained in more detail through examples, on the basis of advantageous embodiments and with reference to the drawings. The described embodiments merely represent possible versions, but the individual features, as described above, can be implemented and omitted independently of each other. In the description, the same elements of the invention are designated with the same reference symbols, and repeated descriptions of the same elements are avoided.

Fig. 1 shows a schematic perspective view of a bending device according to the invention;

Fig. 2 shows a schematic side view of a bending device according to the invention;

Fig. 3 shows a schematic perspective view of a work area of a bending device according to the invention; Fig. 4 shows a schematic plan view of the work area shown in Fig. 3;

Fig. 5 shows a schematic front view of the work area shown in Figs. 3 to 4;

Fig. 6 shows a schematic side view of the work area shown in Figs. 3 to 5;

Fig. 7 shows an enlarged schematic perspective view of the work area shown in Figs. 3 to 6;

Fig. 8 shows a schematic perspective side view of the enlarged section of the work area shown in Fig. 7;

Fig. 9 shows a schematic perspective view of a bending tool according to the invention;

Fig. 10 shows an enlarged schematic perspective view of a bending edge of the bending tool shown in Fig. 9;

Fig. 11 shows a greatly enlarged side view of the bending edge of the bending tool shown in Figs. 9 and 10;

Fig. 12 shows a schematic perspective view of a bearing area of the bending device shown in Figs. 1 and 2;

Fig. 13 shows a schematic side view of the bearing area shown in Fig. 12;

Fig. 14 shows a schematic side view of a bearing element according to the prior art; Fig. 15 shows a schematic side view of an embodiment of a bearing element according to the invention;

Fig. 16 shows a schematic side view of a further embodiment of a bearing element according to the invention;

Figs. 17a to c show schematic side views of a bending tool and a pin contact at three different instants of a bending process;

Fig. 18a shows a schematic side view of geometrical relationships in the bending device;

Fig. 18b shows a schematic side view of geometrical relationships in the work area;

Fig. 19 shows a schematic diagrammatic representation of a guide curve of a bearing element according to the invention. First, a possible structural construction of a bending device 1 according to the invention is explained on the basis of its schematic perspective view in Fig. 1. The bending device 1 has two bending tools 2a, 2b for bending pin contacts 3, which are held down by a holding tool 4.

The bending tools 2a, 2b are mounted on a tool carrier 5 in the form of a mounting plate. The tool carrier 5 is fixed on a drive device 6. The drive device 6 has a bearing 7, in which an eccentric drive shaft 8 sits. An eccentric axle 9, which runs in the longitudinal direction of the drive shaft 8, runs in a transverse direction Z of the bending device 1.

The drive device 6 is supported on the drive shaft 8 and a supporting element 10 in the form of an eccentric rod or rods. A guide axle 12, the longitudinal axis 13 of which runs in the transverse direction Z, in inserted into a guide bearing 11 of the supporting element. The guide axle 12 is movably received in a guide

(not yet shown here) of a bearing element 14, which movably supports the guide axle 12. The drive device 6 and bearing element 14 are immovably fixed to a base plate 15, which is supported on two bases 16.

The holding tool 4 is mounted on a tool holder 17. The tool holder 17 is in such a form that it can move along two vertical guides in a vertical direction Y of the bending device 1. The pin contacts 3 project out of a back of a workpiece 19, which is a plug-in connector. The workpiece 19 is held by a workpiece holder 20. The workpiece holder is in such a form that it can move in a lateral direction X of the bending device 1. Additionally, the workpiece holder 20 can be moved in the transverse direction Z, to transport the workpiece 19 on a production line from one processing device such as this bending device 1 to the next. Fig. 2 shows the bending device 1 shown in Fig. 1, in a side view in the transverse direction Z. Here the eccentricity of the drive shaft 8 becomes specially clear. The effect of the eccentricity of the eccentric axle 9 of the drive shaft 8 relative to a central axis M of the drive shaft is that the tool carrier 5 completes a curved cyclical movement if the shaft 8 completes a full rotation. Between the eccentric axle 9 and the central axis M, an angle of rotation α of the drive shaft 8 is defined. If the eccentric axle 9 and the central axis M are at the same height in the vertical direction Y, the angle α equals 0° or 180°. If the shaft 8 completes a partial rotation corresponding to an angle of rotation α less than 360°, the workpiece carrier 5 completes part of its curved course, which is determined by the geometry of the bending device. The supporting element 10 holds the tool carrier 5 in a desired alignment in a movement plane B defined by the lateral direction X and vertical direction Y for the curved course, while it supports the tool carrier 5 movably in the X and Y directions on the bearing element 14.

In a working cycle, the workpiece 19 is moved by the workpiece carrier using a numerically controlled positioning unit (not shown) in the direction of a work area 21 of the bending device 1 , said work area 21 being formed between the bending tool 2a, 2b and the holding tool 4, and the pin contacts 3 are supported on a workpiece carrier 22. Then the holding tool 4 drops in the vertical direction Y, driven by a pneumatic drive (not shown), onto the contact pins 3, so that the latter are held or clamped between the workpiece carrier 22 and the holding tool 4. The eccentric shaft 8 is then rotated, and the curved movement of the tool holder 5 guides the bending tool 2a, 2b along a cross-section profile (which predetermines a bending contour of the pin contacts) of the holding tool, in such a way that the pin contacts 3 are bent into a desired shape. Fig. 3 shows the work area 21 of the bending device 1, said work area 21 being formed between the bending tools 2a, 2b, the workpiece holder 22 and the holding tool 4. The pin contacts 3 of the workpiece 19 are fixed between the workpiece holder 22 and the holding tool 4, which is dropped onto the workpiece holder 22.

Fig. 4 shows a plan view of the work area 21 shown in Fig. 3. The holding tool 4 is not shown, to give a view of the pin contacts 3. Fig. 5 shows the work area shown in Figs. 3 and 4, in a schematic front view.

Fig. 6 shows the work area 21 shown in Figs. 3 to 5 in a schematic side view along the transverse direction Z. The pin contacts 3, which project out of the workpiece 19, are clamped tightly between a holding element 23 of the holding tool 4 and a supporting element 24 of the workpiece holder. A bending edge 25 of the bending tool 2a is aligned onto the pin contacts 3.

Fig. 7 shows a schematic perspective view of the work area 21. The pin contacts 3 are put down and supported on the workpiece holder 24, on a supporting surface 26 of the holding element 23 facing in a vertical direction Y. The holding element 23 of the holding tool 4 holds the pin contacts 3 down. A bending side 25a on the bending edge 25 runs in the transverse direction Z, parallel to the row of pin contacts 3, and points in their direction.

Along the bending side 25a of the bending tool 2a, between position-determining elements 27 which project from the bending edge 25, bending positions 28 in the form of indentations or grooves running round the bending side 25a are formed. The bending positions 28 are arranged along the bending side 25a in the transverse direction Z, at equal intervals, and their positions are matched to positions of the pin contacts 3 in the transverse direction Z along the work area 21. During the bending process, the pin contacts 3 are positioned and centred in the bending positions 28. Movements of the pin contacts 3 parallel to the transverse direction Z are suppressed during the bending process by the bending-position-determining elements 27, which hold the pin contacts 3 laterally.

Fig. 8 shows the work area 21, enlarged in a lateral perspective view. In a front end section or marginal area 29 of the bending tool 2a, a front surface 30 of the bending tool runs diagonally from an underside 31 onto a top side 32 of the bending tool 2a. Thus the bending tool 2a tapers in the lateral direction

X to the bending edge 25, which is received and held in the form of a carbide rod with a round cross-section in a fitting element 33 which forms a sliding bearing. The fitting element 33 provides a circular receptacle 34 for the bending edge 25, and the bending edge 25 is received in said receptacle 34 with loose fit, so that it can rotate around a longitudinal axis E of the bending edge 25 or bending surface 25a.

To receive the bending edge 25 rotatably in a fitting element 33 which functions as a sliding bearing, very narrow production tolerances are required. Thus in the case of a length of the bending edge 25 in the transverse direction Z of 50 millimetres to 100 millimetres, a straightness tolerance of a maximum of 0.1 millimetres is permitted, to ensure that rotation is possible. The concentricity of the bearing or of the fitting element 33, which forms a receptacle for the bending edge 25, and the bending edge 25, should have a tolerance of IT6 or less.

In front of the marginal area 29, the top side 32 of the bending tool 2a is provided with a recess 35, in which the surface of the bending tool 2a in the vertical direction Y is below the top point of the circular cross-section of the bending edge 25 in the vertical direction Y. The effect of this recess 35, and of the course, which tapers in the lateral direction X, of the bending tool 2a in the marginal area 29, is that the bending edge 25 projects from the bending tool 2a in both the vertical direction Y and the lateral direction Y, in an exposed position so to speak. This ensures that when the pin contacts 3 are processed by the bending tool 2a, they are touched only by the bending edge 25 and not by other sections of the bending tool 2a.

It can also be seen in Fig. 8 that the holding element 23 of the holding tool 4 has, on a holding edge 36 facing the work area 21, a rounded cross-section with a radius f. The pin contacts 3 are bent along the radius f of the holding edge 36. Thus the pin contacts 3 have a first horizontal section 37 which lies on the supporting surface 26 of the supporting element 24 and is clamped between the holding element 23 and the supporting surface 26. Along the holding edge 36 of the holding element 23, the pin contacts 3 have a wide, bent section 38. An inner radius of the curve of the bent section 38 corresponds approximately to the radius f of the holding edge, which is to be understood as a bending radius. A third, vertical section 39 of the pin contacts 3 is joined to the second, bent section 38. With their vertical section 39, the pin contacts 3 are, for example, inserted into a printed circuit board (not shown) and connected electrically conductingly to its tracks (not shown).

Fig. 9 shows a schematic perspective view of a bending tool according to the invention 2a. The bending tool 2a is in the form of a bending plate, the length of which extends in the lateral direction X. In the bending tool 2a, fixing means 40 are formed in the form of fixing holes, using which the bending tool 2a can be fixed on the tool carrier 5. Parallel to a direction of a longitudinal axis W of the bending tool 2a, the fixing means 40 have a gap n. Because of the gap n between the fixing elements 40, the bending tool can be tilted around a transverse axis Q running in the transverse direction Z, so that the alignment of the longitudinal axis W of the bending tool 2a, and thus the alignment of the bending edge 25 or bending side 25a relative to a contact point (not yet shown here) with the pin contacts 3, can be varied.

Fig. 10 shows an enlarged schematic perspective view of the bending edge 25 on the marginal area 29 of the bending tool 2a. The fitting elements 33 are used as fixing elements for the bending edge 25. The bending edge 25 is carried in the receptacle 34 so that it can rotate, and secured against movements in the transverse direction Z. A transverse opening 41 of the fitting element 33, extending into the receptacle 34, simplifies the adjustment of the bending edge 25. A lengthways end 42 of the bending edge 25 is in the region of the opening 41.

It also becomes clear in Fig. 10 that the position-determining elements 27 are in the form of eyelets which extend perpendicularly away from the marginal area 29 of the bending tool 2a. The bending edge 25 is pushed through eyelet-like openings 27a in the position-determining elements, so that they enclose the bending edge 25 and bending side 25a in sections.

Fig. 11 shows a greatly enlarged side view of the marginal area 29, with the bending edge 25 of the bending tool 2a shown in Figs. 9 and 10. The receptacle 34 of the fitting element 33, which functions as a fixing element and bearing, encloses an outer radius i of the bending edge 25. At its lengthways end 42, the bending edge 25 is provided with a chamfer 43 which runs along its outer radius i, and makes inserting the bending edge 25 into the receptacle 34 easier.

Fig. 12 shows a schematic perspective view of a bearing area 44 of a bending device 1 according to the invention. In the bearing area 44, the bearing element 14, which receives the guide axle 12, is mounted. The guide axle 12 is held in the guide bearing 11, which is in the form of a ball bearing inserted into a bearing socket 45 of the supporting element 10, so that it can rotate relative to the supporting element 10.

Fig. 13 shows a schematic side view of the bearing area 44 shown in Fig. 12. The bearing element 14 is provided with fixing means 46 in the form of holes, using which the bearing element 14 can be connected to a fixing block 47, which is mounted on the base plate 15. Through the fixing means 46, for example, stud bolts can be put, and can be inserted into corresponding threaded holes (not shown) of the fixing block 47, which is used to some extent as an adapter to fix the bearing element 14 on the base plate 15.

Fig. 14 shows a schematic side view of a bearing element 14' according to the prior art. The bearing element 14' has a receptacle 48' which is in the form of a guide for the guide axle 12, and which opens to a side 49 of the bearing element 14' facing in the direction of the drive device 6. An upper guide surface 51 ' and a lower guide surface 52' enclose the guide 48', and are arranged parallel to each other, until they grade into a semicircular termination 53 of the guide 48'. The distance j between the guide surfaces 51 ', 52', measured perpendicularly from the guide surfaces 51 ', 52', is minimally greater than a thickness of the guide axle 12, so that the latter, with its longitudinal axis 13, is guided in the guide 48' safely and almost without play along a straight guide line 54', which runs centrally between the guide surfaces 51 ', 52', with a gradient of 55°, according to the prior art.

As mentioned above, the straight course of the guide 48, with a fixed gradient of 55°, is not optimally adapted to a bending radius of the pin contacts 3, and is disadvantageous, because the bending tool 2a, 2b, with a straight guide 48' with a predetermined angle of slope, does not roll along a surface of the pin contacts 3, but instead, in sections, slips, rubs and thus damages the surface of the pin contacts, causing unwanted abrasion.

Fig. 15 shows a schematic side view of an embodiment of a bearing element 14 according to the invention. The guide 48 has two guide surfaces 51, 52 with a constant gap between them. Centrally between the guide surfaces runs a guide line 54, along which the longitudinal axis 13 of the guide axle 12 is guided. The guide surfaces 51, 52 are curved in such a way that the guide 48 has a first curved section 55 and a second curved section 56. In the first curved section 55, the guide line 54 has a first curve with a radius T ₁ . In the second section 56, the curved line 54 has a second curve with a second radius of curvature r ₂ . The different radii of curvature X _\ , r ₂ of the guide line 54 cause a tilting movement of the bending tool 2a, 2b, said tilting movement being adapted to the workpiece 19, encouraging unwinding of the bending edge 25 in the bending tool 2a, 2b or along a desired curve of the bent section 38 of the pin contacts 3, and thus reducing unwanted relative movements and resulting friction between the bending side 25a and the pin contacts.

Fig. 16 shows a schematic side view of a further embodiment of a bearing element 14 according to the invention. Here the guide 48 is straight, and correspondingly has a straight guide line 54. However, the guide 58 is formed in a bearing module 58, which is formed so that it can rotate in the movement plane B of the bending tool 2a, 2b. A gradient of a guide angle β of the guide line 54 is thus adjustable. Thus the guide angle β can be adapted to the requirements of the relevant bending processing and/or to the radius of curvature of the bent section 38 of the pin contacts 3, which helps to reduce unwanted abrasion of the pin contacts 3.

For simplified adjustment, the bearing module 58 is in the form of a disc, which is provided with adjustment means 59 in the form of long holes running along a radius of the bearing module 58. The positions of the adjustment means 59 are formed on positions of locking means 60 in the form of through holes or threaded holes, into which, for example, threaded bolts for locking the bearing module 58 can be inserted, in the bearing element 14. The bearing module 58 can be separated from the bearing element 14 and replaced by a different bearing element 58, the guide 48 of which has different dimensions or, for example, a different course of the guide line 54. Figs. 17a to 17c show schematic side views of a bending tool 2a, 2b and of a pin contact 3, at a different instant of the bending process in each case. In Fig. 17a, the bending side 25a of the bending tool 2a, 2b is in contact with the pin contact 3, with its upper section, at a contact point 61. A measurement 1 is the length of the pin contact above the contact point. An angle γ is the angle between the first or horizontal section 37 of the pin contact 3 and the third or vertical section of the pin contact 3. In Fig. 17a, the angle γ is still small, about 5°. In Fig. 17b, the bending process has progressed, and the angle is about 45°. In Fig. 17c, the bending process is completed, and the angle γ is 90°.

The unbent first section 37 of the pin contact 3 has a longitudinal axis L. The bent third section 39 of the pin contact 3 has a longitudinal axis L'. The contact point 61 is arranged in the region of the bent section 39, and optimally during the bending process should not be moved in the direction of the longitudinal axis L'.

During the bending process, it is desirable that the position of the contact point 61 on the pin contact 3 does not change, i.e. that the length 1 of the pin contact above the contact point 61 relative to the longitudinal axis L' remains as constant as possible. In this way friction and/or wear effects between the bending edge 45 and the surface of the contact pin 3, and abrasion resulting from them, are avoided. Optimally, the bending side 25a rolls along the surface of the contact pin 3 if the position of the contact point 61 and/or the length 1 change.

A tilting movement, adapted to the position of the contact point 61, of the bending tool 2a, 2b is achieved by optimising the guide line 54, which represents a trajectory or path curve of the guide axle 12.

Sliding of the surface of the contact piece 3 along the outer radius of the bending edge 25 is avoided by the bending edge 25 rotating with the bending side 25a and the position of the contact point 61 on the surface of the bending edge 25 remaining constant during the bending process.

Figs. 18a and 18b show schematic side views of the geometrical relationships in the bending device 1 and a schematic side view of the work area 21. In Figs. 18a and 18b, measurements and angles are drawn in as the parameters which influence the bending process and/or the position of the contact point 61 according to the alignment of the bending side 25a on the bending edge 25. Thus the bending edge 25 is in an initial position A, in which the bending process begins. In the initial position A, the angle α according to the invention is greater than 0°. Thus the drive axle has an offset or vertical offset d. There is thus a gap, called gap a, between the eccentric axle 9 and the central axis M of the drive axle.

The eccentric axle 9 and the longitudinal axis 13 of the guide axle 12 have a gap c. The central axis

M of the drive axle 8 is at a height k above the top of the base plate 15. The longitudinal axis L of the horizontal section 37 of the pin contacts 3 are above the top side of the base plate 15, with a gap d. A centre or central axis 62 of the workpiece carrier 20 and workpiece 19 has a gap d to the centre of the bending radius f of the holding edge and of the curved section 38 of the pin contacts.

Fig. 18b shows, in particular, the arrangement of the bending radius f and of the outer radius i of the bending edge 25 and/or of the bending side 25a formed on its outer radius in the work area 21. The centre of the bending radius f and the centre of the radius i of the bending edge have a gap h. The horizontal section of an unbent pin contact 3 ' or bent pin contact 3 ' ' has a thickness g. Fig. 19 shows a schematic diagrammatic representation of an exemplary optimal guide line or path curve 54 for the guide axle 12 for the bending tool 2a, 2b. Taking account of the gaps and angles a to k, the result is an optimal course of the guide line 54 for the bending process. It becomes clear that the guide line 54 has the first curved section 55 and the second curved section 56. An equalisation straight line 54a or regression line has a gradient y, and is inclined relative to the X axis or lateral direction X of the bending device 1 at the guide angle β.

If it is economically unjustifiable to provide, for each of different workpieces, a supporting element 10 with a specific guide line which is adapted to the workpiece 19, a desired inclination β of the guide line 54 can be set, for example using the bearing module 58, to minimise the friction between the bending edge 25 and the pin contacts 3.

It has been shown to be optimal for minimising the friction between the bending edge 25 and the surface of the pin contact 3 if the eccentric axle 9 is not at the same height in the vertical direction Y with the central axis M of the drive shaft 8, i.e. does not have an angle of 0° or 180°. In this way the bending process begins from an initial position A in which the bending tool 2a, 2b or its longitudinal axis W is angled relative to the longitudinal axis L of the contact pin 3.

A further advantage results from the fact that the distance between the bending tool 2a, 2b and the holding edge 36, and/or the distance h between the centre of the bending radius f and the centre of the radius i of the bending edge, should be as small as possible. However, this distance cannot be chosen to be arbitrarily small, because when the pin contacts are bent, the forces which occur are greater the smaller the distance h is. The higher the forces are, the stronger the stresses on the workpiece 19 become, and because of the bending forces it can itself be bent or distorted. However, distortion of the workpiece 19 affects the parameters of the bending process so that optimising it seems to be impossible. There is also the danger of damaging the workpiece 19.

It has also been shown to be advantageous to polish the bending edge 25, so that it has a degree of roughness R _a of about 0.1. A sliding plating of the bending edge is also advantageous. Thus the bending edge can be coated with, in particular, a plating containing carbon, such as a TT-DLC plating, as the sliding plating. The TT-DLC plating is made of amorphous carbon and can be applied by a PACVD method. Such a plating can reduce the friction to a value of μ < 0.15. The plating can have a Vickers hardness of 2,000 to 3,500 HV. Within the idea of the invention, differences from the embodiments described above are possible.

Thus the bending device 1, instead of being implemented with a mechanical control of the course of the curve of the bending edge 25 and bending side 25a in the movement plane B in the form of a mechanical drive device 6 and the mechanical guide 54, could also be implemented with electrical servo or stepping motors in an X-Y arrangement. The supporting element 10 can be attached to the drive device 6 and supported on a bearing element

14 in any way, provided that a suitable path course of the bending edge 25 relative to the pin contact 3 can be implemented.

The vertical guide 18 for the holding tool 4 can be implemented pneumatically or by other commonly used drives. However, a pneumatic drive is advantageous because with it the greatest possible holding forces acting in the Y direction can be exerted on the pin contacts 3. Additionally, the shape of the workpiece holder 22 and its holding element 20 and the supporting element 24 of the workpiece holder 22 can be adapted in any way to the relevant bending task. The outer contour of the position-determining elements 27 can be adapted so that the bending-position-determining elements 27 hold the pin contacts 3 in the bending positions 28, undamaged and with small deviations in the transverse direction Z. The marginal area 29 of the bending tool can be formed and tapered in any way, so that the bending edge 25 can be guided optimally along the bent section 38 of the pin contacts 3. Fitting elements 33, which are formed as bearings for the bending edge 25 which is received rotatably on the marginal area 29 of the bending tool 2a, 2b, can be adapted to the relevant requirements for rotatable support of the bending edge 25.