DE102018114579B3 - Method and device for burr-free cutting of a wire and a correspondingly separated piece of wire and hairpin - Google Patents

Abstract

The invention relates to a method for burr-free cutting of a wire (12), in particular of polygonal cross-section, characterized by the following steps: - forming the wire (12) at a wire longitudinal position (62) by moving two of them together in a first plane ( 56) opposite Umformabschnitten (40) of a first forming unit (14) along a first axis of movement (Z), wherein during forming of the wire (12) the forming sections (40) of the first forming unit (14) are always spaced apart, so that the wire cross-section at this first forming step is tapered from two opposite sides (44) and a tapered wire cross-section remains, - forming the wire (12) at the same wire longitudinal position (62) by moving two forming sections (46) opposite each other in a second plane (56) a second forming unit (16) along a second axis of movement (Y), the U mformabschnitte (46) of the second forming unit (16) are always spaced apart, so that the already tapered wire cross-section is tapered in this second forming step of two other opposite sides (50) ago and the already tapered wire cross section remains in a further tapered shape; and - tensile severing of the wire (12) at the same wire longitudinal position (62) with now tapered wire cross section by applying a tensile force to the wire (12).

Description

The invention relates to a method for burr-free cutting of a wire having the features of the preamble of claim 1. In addition, the invention relates to a device for burr-free cutting of a wire having the features of the preamble of the independent claim. In addition, the invention relates to a correspondingly separated piece of wire and a hairpin.

Methods and devices of the type mentioned above are known to the applicant from practice. Thus, in the manufacture of electric motors for traction drives individual winding elements (plug-in coils, so-called. "Hairpins") produced, which are further processed in the process to a complete stator winding. In order to achieve a higher efficiency of electric machines due to higher degree of filling, in the hairpin technology of round wires on wires with rectangular cross section has been passed. As part of the production of plug-in coils corresponding wire sections must be cut and cut from endless material, which are welded together after positioning on the stator.

DE 10 2011 116 529 A1 describes a method for separating a Einzellitzendrahtes.

DE 2 245 771 describes an apparatus and method for hooking wire spiders.

DE 10 2017 205 633 A1 describes an apparatus and method for cutting a wire.

A separation of the wire sections is usually carried out by shearing, wherein at the wire ends end surfaces arise whose edges unbroken, i. sharp-edged and with burrs (ridges) are afflicted. These ridges can, if they are not laboriously removed in an additional step, for example, manually, during installation of the plug-in coils in an insulation (insulation paper) retract, which is already in the groove of the provided stator of the electric motor. Therefore, there is a risk that the insulation will be destroyed, which may cause malfunction of the electric motor.

The invention has for its object to enable a simple and constructive means a reliable and burr-free as possible separation of wires. A reworking of the wires at the separation points should be avoided.

The invention solves this problem by a method having the features of claim 1. Thereafter, the method is characterized by a plurality of steps, which are described below.

First, a (burr-free) deformation of the wire takes place at a wire longitudinal position in a first forming step by moving two forming sections of a first forming unit opposite each other in a first plane along a first axis of movement. In this case, the wire cross-section is tapered in this first forming step from two opposite sides, for example. Of two narrow sides. When forming the wire, the forming sections of the first forming unit are always spaced from each other so that a tapered wire cross-section remains. Thereafter, a deformation of the wire takes place at the same wire longitudinal position in a second forming step by moving two opposite each other in a second plane forming sections of a second forming unit along a second axis of movement. In this case, the already tapered wire cross-section is tapered in this second forming step by two other opposite sides, for example. Of two broad sides. When forming the wire, the forming sections of the second forming unit are always spaced apart, so that the already tapered wire cross section remains in a further tapered form. It remains at the wire longitudinal position so a material web, which is arranged offset from the original cross-sectional shape of the wire to the inside. In particular, the material web may have the same cross-sectional center as the original cross-section of the wire. In particular, the material web is at least two, preferably all, opposite sides each equidistant from the original cross-sectional shape inwardly offset. At this time, before and after the wire longitudinal position, the intended separation point, arranged wire sections over the material web still cohesively connected to each other. Thereafter, ie after the second forming step, the wire is drawn at the same wire longitudinal position by applying a tensile force (acting at least proportionally along the wire longitudinal direction) to the wire. Thus, the wire is separated at the wire longitudinal position.

Such separation has the advantage that the occurrence of serrations can be avoided by providing the method at a corresponding wire longitudinal position (separation point) a plurality of forming steps and a subsequent draw separation, as described above. By forming the wire by means of the forming sections of the wire is fitted at the wire longitudinal position, so that a defined vulnerability is created at the separation takes place by pulling the wire. Since the wire by forming with the forming sections also before and after the separation point (Dividing plane) is tapered, the wire ends have a tapered, for example, chamfered or conical shape. Thus wire sections with wire ends can be provided that are ideally suited for plug-in spools (hairpins), since these can be easily inserted into the insulation of the grooves of a motor due to their tapered, eg conical, wire ends. In other words, a simpler insertion of the wire without damaging the insulation paper in the stator is made possible because the "initial cross-section" (wire end) during insertion is smaller. The burr-freeness of the wire ends helps increase safety and reduce rejects. In addition, the process is economically favorable because the service life of the forming sections is comparatively high, because the forming sections only penetrate into the wire material (eg copper), deform it only and do not touch each other.

The proposed method can be used in a complex process chain. The adjacent methods may e.g. Inserting the insulation into the groove of the stator, forming in several steps of hairpins or stripping the wire ends of a hairpin. The process chain can be done, for example, with the order Stripping - first forming step, second forming step and draft separation - forming in the hairpin shape. All steps can be carried out on a machine with different stations of a preferably longitudinally controlled system. Even individual self-contained process units are conceivable.

The term "burr-free cutting" is to be understood in the present case that a separation takes place burr-free with respect to the side surfaces of the wire. Thus, the wire should not have laterally over the side surfaces of the wire protruding burrs (Schergrate) after separation. At the end faces of the wire may be due to the drafting a certain burr formation done, but for lack of lateral projection for the further use of the separated pieces of wire is not important.

The wire may be a wire of soft material, such as copper wire. The wire can be enveloped by an insulation, for example a lacquer layer. The wire may have a polygonal, in particular four-edged cross-section, for example a rectangular cross-section, whereby a rectangle here can be understood to mean a rectangle with rounded corners and not necessarily a rectangle in the strictly geometrical sense. In particular, in the method, however, a wire with a cross section with two parallel straight sides, or in particular with four straight sides, of which two are each parallel to each other.

The forming sections of the forming units are in each case displaceable along their movement axis between a starting position (forming sections are located outside the wire) and an end position (forming sections have penetrated the wire and are not moved further toward one another). The wire-facing ends (tool tips) of the forming sections do not touch each other in the end position.

The forming sections form part of a forming tool which, in addition to a forming section (actual processing section), can also have a shank section for fastening the forming tool, for example on a tool carrier or a tool holding plate. The forming tool may be mounted in a forming unit and may be driven by the forming unit, as will be described later.

As discussed above, the forming steps described are sequential. Hereby, a collision of the forming sections can be avoided. In addition, the wire material thus has the possibility during the forming his "way to seek" to evade the forming sections by plastic deformation. As a result of the successive forming steps, the wire material is given the opportunity to "dodge" in the direction of the respective other process step, whereby a reduced burr formation or a reduced "throw-up" formation can be achieved. A coordination of the forming units can be done by electrically driven "cams" (cams or eccentrics) or by a CNC system.

The forming sections of the first forming unit may lie in a (first) plane and be moved in this plane and / or the forming sections of the second forming unit may lie in a (second) plane and be moved in this plane. The arrangement of each opposite forming sections in a plane contributes to the fact that the wire material is not sheared, but deformed (forming sections are not like scissor blades offset from each other). The formation of serrations can thus be avoided.

So that the forming sections are arranged opposite one another in a plane, it can be meant that the respective tool tips lie in a plane in which the respective movement axis of the forming sections lies. The tool tips of the forming sections of the first forming unit can therefore lie in the first plane and the first axis of movement of the forming sections is also in this plane. Accordingly, the tool tips of the forming of the second forming unit in the lie second plane and the second axis of movement of Umformabschnitte is also in this second level.

The first level and second level may be congruent. The first level and second level can therefore lie on top of each other. In other words, the forming sections of the first forming unit and the forming sections of the second forming unit can all lie in a common plane and be moved in this plane during forming. In particular, the tool tips can all lie in a common plane and be moved in this plane during forming. This ensures a particularly accurate deformation of the wire at exactly the same wire longitudinal position, as positioning errors are avoided.

Conveniently, the first movement axis (along which the forming sections of the first forming unit are displaced) and the second movement axis (along which the forming sections of the second forming unit are displaced) can be oriented orthogonal to one another. The axes of motion can intersect each other. Hereby, in particular a polygonal or square (eg rectangular) wire can be machined on the respective opposite side surfaces, wherein good forming properties can be achieved (wire material can move in the direction of the other process).

As mentioned above, when forming the wire, the forming sections do not contact each other and are always spaced apart along their axis of movement. This ensures that at the wire longitudinal position (separation point) abutting wire sections remain connected to each other by a sufficiently strong cohesive connection to achieve the desired contour of the wire ends during drafting.

In an advantageous manner, the forming sections of the first forming unit and / or the forming sections of the second forming unit can each be moved in the opposite direction, in particular and with the same speed, during the respective forming. Hereby, a uniform deformation of the wire can be achieved on the opposite sides of the wire, whereby undesirable deformation of the wire, for example, a bending or buckling, can be avoided. This contributes to the reduction of rejects.

In an expedient manner, the forming sections of the first forming unit and / or the forming sections of the second forming unit can each be moved intermittently or continuously (toward each other) during forming of the wire. Hereby, depending on the properties of the wire material and / or configuration of the forming sections, a desired deformation can be achieved. With continuous movement of the forming sections, a short forming time can be achieved. With intermittent motion, the wire material can be given time to seek out "the right path" during forming.

Specifically, the wire can be fed to the forming units from an input side and guided by means of a wire guide along a wire passage direction or wire longitudinal direction. This ensures a supply of wire with structurally simple means. By the guide, a stabilization of the wire, so that it is held securely, in particular during the forming and pulling the train. After disconnecting, the wire can be removed on the output side.

In a preferred embodiment, the wire can be clamped for traction separation in a gripper unit. The gripper unit, preferably the gripper unit and the forming units (unit formed by gripper unit and forming units), can be moved relative to the wire. This allows a structurally simple separation of the wire at the wire longitudinal position, as this only a fixation of the wire at one point and a relative movement is required (speed of the gripper unit v _{gripper unit} is greater than the speed of the wire v _wire ). For example. If necessary, the gripper unit can be accelerated, so that by clamping the wire in the gripper unit at the wire longitudinal position (separation point) by the speed _difference (V _{gripper unit} > v _wire ), an increasing tensile stress until the wire is torn off. A delay of the wire feed along the wire feed direction before the gripper unit at a constant speed of the gripper unit would be a conceivable solution for obtaining a speed difference. Even then, v _{gripper unit is} > v _wire . The gripper unit may be arranged downstream of the forming units in the wire passage direction.

Conveniently, the forming units during the first forming step and / or during the second forming step along the wire longitudinal direction no relative movement to the wire perform (relative speed is zero). This can be achieved during the forming an accurate deformation at exactly the same wire longitudinal position, since positioning errors that can be caused by moving and re-fixing the wire can be avoided. For this purpose, the forming units can be moved synchronously with the wire or be together with the wire at a standstill.

As already indicated, the first forming step and / or the second forming step can take place on the wire moved along the wire longitudinal direction, wherein the forming units are moved synchronously with the wire (no relative speed between forming units and wire).

This can be a quick conversion and thus achieve a short cycle time.

In the method, the wire can be fed continuously, in particular at a constant rate, from a wire source to the forming units. The wire source may be a wire coil. The wire can be moved as straight as possible along a wire passage direction in a portion of its transport. The forming units can be temporarily moved with the wire at the same speed. During this co-movement, the first and the second forming step can be carried out without a relative movement between the wire and the forming units between the first forming step and the second forming step. Expediently, the forming sections of the first forming unit and the second forming unit lie in the same plane for this purpose. Following the second forming step, the section of the wire lying in the transport direction behind the forming units or behind the intended separation point can be accelerated, for example via the gripping device, whereby a tensile force can be applied to the wire and the wire at the wire longitudinal position with a tapered wire cross section is separated. The speed of the section of the wire lying in the transport direction before the forming units or before the intended separation point can preferably remain constant. Following the second forming step, the forming units can be braked and moved back against the transport direction, so that the process can be carried out again. The speed of movement of the forming units, the transport speed of the wire and the movement distance of the forming units can be adjusted to the desired wire length.

After tensile separation, the severed piece of wire can be removed from the gripping device and, for example, formed into a hairpin.

For further embodiment of the method, the measures described in connection with the device can also be used, which are described below.

The implementation of the method according to the invention is in particular by means of an embodiment of the devices described below.

The object mentioned above is also achieved by a device having the features of the independent claim. The device for (with respect to the side surfaces) burr-free separation of a wire with polygonal, in particular four-edged (for example, rectangular), cross-section is characterized by the features described below.

The device has a first forming unit for forming the wire with two forming sections opposite each other in a first plane and movable toward each other along a first movement axis by a tool drive. When forming the wire, the forming sections of the first forming unit are always spaced apart from each other so that the wire cross section can be tapered from two opposite sides to form a tapered wire cross section by means of the forming sections. The apparatus further comprises a second forming unit for forming the wire with two forming sections opposite each other in a second plane and movable towards each other by a tool drive along a second movement axis. When forming the wire, the forming sections of the first forming unit are always spaced apart from each other so that the already tapered wire cross section can be tapered from two further opposite sides to a further tapered form by means of the forming sections. The device also has a, preferably downstream of the forming units along the wire longitudinal direction, gripper unit for tensile separation of the wire. By means of the gripper unit, the wire can be clamped, so that, for example, by relative movement between the gripper unit and wire, a tensile separation of the wire can be done. In the apparatus, the forming sections of the first forming unit and / or the forming sections of the second forming unit have a greater width than the wire sides respectively formed by these forming sections. This ensures a uniform deformation of the wire at the wire longitudinal position (separation point). In addition, there is the possibility to work with only one forming section wires with different cross-sections whose side lengths are shorter than the width of the forming sections.

With regard to the advantages of this device, reference is made to the relevant explanations in connection with the method.

In a preferred embodiment, the forming sections of the first forming unit can be arranged in a (first) plane together with the first movement axis and / or the forming sections of the second forming unit can be used in a (second) plane together with the be arranged second movement axis. This contributes to the wire material not being sheared but deformed as described above. Burrs can thus be avoided. So that the forming sections are arranged opposite one another in a plane, it can be meant that the respective tool tips lie in a plane in which the respective movement axis of the forming sections lies. The tool tips of the forming sections of the first forming unit can therefore lie in the first plane and the first axis of movement of the forming sections is also in this plane. Accordingly, the tool tips of the forming sections of the second forming unit can lie in the second plane and the second axis of movement of the forming sections is also in this second plane.

Advantageously, the above-described first level and second level may be congruent with each other. In other words, the forming sections of the first forming unit and the forming sections of the second forming unit can all be arranged in a common plane. This ensures accurate deformation of the wire at exactly the same wire longitudinal position, since positioning errors are avoided, as described above.

Conveniently, the first forming unit and the second forming unit may be arranged such that the first movement axis and the second movement axis are orthogonal to each other. In this case, the first movement axis and the second movement axis can intersect each other. Thus, a polygonal or four-edged (for example, rectangular) wire can be machined on the respectively opposite side surfaces, wherein good forming properties can be achieved. The forming units may be attached to a frame or a housing. The forming units thus fastened can form a forming unit.

Specifically, the first forming unit and / or the second forming unit may each comprise / has a threaded shaft coupled to the tool drive having two threaded sections with equal but counter-oriented thread pitches, one forming section each being coupled to a threaded section. This is a structurally simple and stable design of a forming unit with mutually synchronized Umformabschnitten (same speed, same travels, but opposite directions) created.

As a threaded shaft, a ball screw can be used, which has favorable friction properties. The threaded shaft can be mounted by means of bearing blocks and, for example, be mounted on a base plate of the forming unit. The forming sections of a forming tool can, for example, be integrally connected to a shaft via which the forming tool can be fastened to a tool holding plate. The tool holding plates can each be connected to a running body, on or in which a nut corresponding to the threaded shaft, for example a spindle nut, is inserted. The tool drive, for example an electric motor, can preferably be coupled to the threaded shaft by means of a coupling.

In a preferred embodiment, the forming units and / or the gripper unit can be arranged and fastened on a (common) receiving plate. Hereby, a modular unit is formed, which can be handled as a unit and, for example, can be integrated into a longitudinally controlled system.

The receiving plate may have holes for attachment of components and / or recesses for gripping the receiving plate. The forming units can be attached by means of a frame or by means of a housing to the receiving plate. The gripper unit can be attached by means of a tool holder on the receiving plate.

Advantageously, the receiving plate can be guided displaceably by means of a guide along the wire longitudinal direction, wherein a motor drive can be coupled to the receiving plate, by means of which the receiving plate can be driven in the wire longitudinal direction. Hereby, the receiving plate and thus the forming units and the gripper unit can be moved with or relative to the wire. Forming can thus take place on the moving wire. By relative movement of the receiving plate or the gripper unit relative to the wire, a tensile separation can be realized. The guide may include rails and carriages corresponding to the rails to which the receiving plate is attached. The motor drive can have a drive motor, for example an electric motor. The drive motor can be controlled accordingly with respect to feed, frequency, amplitude, acceleration, speed, position and / or torque.

In general, the forming sections can each have a tool tip that tapers towards the free end, for example, tapered or chamfered. One could also speak of cutting tool tips.

Specifically, the forming sections of a forming unit, in particular the first forming unit, a tool tip with a first Have wedge angle and the forming sections of the other forming unit, in particular the second forming unit, may have a tool tip whose wedge angle is at least directly to the tool tip smaller than the first wedge angle. Thus, corresponding forming sections can be provided for the desired forming, wherein the remaining material thickness of the wire during forming with the first forming unit is greater than during forming with the second forming unit.

Both in the method according to the invention and in the device it can be provided that the remaining material thickness in the respective direction of movement in the first forming step is greater than in the second forming step (remaining material thickness, for example, less than 0.2 mm).

Thus, the first forming unit can be used for forming with a smaller penetration depth (penetration depth in each case, for example, approximately 0.5 mm). In this way, the wire can, for example, be waisted from its opposite narrow sides. Such a transformation can be referred to as "coining". The second forming unit can be used for forming with a higher penetration depth (remaining material thickness between the tool tips in the end position, for example, about 0.2 mm). Although in this forming no separation, but only a deformation of the material takes place, one could call such a transformation due to the higher penetration depth of Umformabschnitte as "cutting".

Conveniently, the forming sections of the other forming unit, in particular the second forming unit, a tool tip having a continuous wedge angle. This allows a cost-effective production of such a forming section.

Alternatively, the forming sections of the other forming unit, in particular the second forming unit, having a tool tip having a plurality of sections with different wedge angles, wherein the wedge angle at the free end of the tool tip is smaller than a subsequent to the side facing away from the free end wedge angle. By such a wedge angle at the free end of penetration of the forming section is facilitated in the wire, which can be done by the subsequent (larger) wedge angle a larger transformation. Between the wedge angle at the free end and the subsequent (larger) wedge angle, the forming section can have a straight course. This serves the stability of the forming tool, ensures a proper opening (certain entrance angle) when penetrating the wire material and prevents burr formation.

For further embodiment of the device can also serve the measures described in connection with the method.

Part of the present invention is also a piece of wire which has been separated from a wire, in particular by use of a described method and / or using a device described. Such a piece of wire comprises a tapered portion created by plastic forming, which is offset inwardly from an original outside of the wire in a radial wire direction. The tapered section merges into a fracture surface created by draft separation, which has a surface structure due to this separation process.

The tapered portion has a first radially inwardly sloping surface and a second radially inwardly sloping surface. The transition of the first sloping surface to the fracture surface is formed by a first transition edge and the transition of the second sloping surface to the fracture surface is formed by a second transition edge.

The first transition edge and the second transition edge are rectilinear.

The first transition edge and the second transition edge are arranged orthogonal to each other.

The distance between the two first transition edges to each other is greater than the distance between the two second transition edges to each other.

The piece of wire may have a rectangular original cross-section.

The piece of wire may in particular comprise copper. In particular, comprise or consist of a copper core with insulating coating.

Preferably, the tapered portion has been created in the first and second forming steps described above.

The first and second sloping surfaces extend from the original outside to the fracture surface. It is possible that the first and / or the second sloping surfaces have areas with different pitch. It is thus possible that the rate at which the surfaces as viewed along the wire longitudinal direction varies radially inwardly from falling locally.

Part of the invention is also formed from one of the pieces of wire just described hairpin hairpin.

• 1 eine Vorrichtung zum gratfreien Abtrennen eines Drahtes in einer schematischen perspektivischen Ansicht;
• 2 eine Umformeinheit der Vorrichtung aus 1 in Alleinstellung in einer perspektivischen Ansicht;
• 3 die Umformabschnitte der Umformeinheiten der Vorrichtung aus 1 an einem Draht in einer schematischen perspektivischen Ansicht;
• 4 einen Abschnitt des Drahtes aus 3 nach dem ersten Umformschritt und dem zweiten Umformschritt in einer perspektivischen Ansicht in Alleinstellung;
• 5 die Umformabschnitte der zweiten Umformeinheit nach einem Verjüngen des Drahtquerschnitts durch Eintauchen in den Draht (Endposition) in einer geschnittenen Ansicht;
• 6 ein Umformabschnitt der ersten Umformeinheit der Vorrichtung aus 1 in mehreren Ansichten;
• 7 ein Umformabschnitt der zweiten Umformeinheit der Vorrichtung aus 1 in mehreren Ansichten;
• 8 eine Trennstelle eines Drahtes nach dem Durchführen des erfindungsgemäßen Verfahrens, wobei beide resultierenden Drahtstücke gezeigt sind;
• 9 eine weitere Trennstelle eines Drahtes nach dem Durchführen des erfindungsgemäßen Verfahrens, wobei nur ein Drahtstück gezeigt ist und der Draht einen runden Querschnitt aufweist; und
• 10 einen Hairpin;

The invention will be explained in more detail below with reference to the figures, wherein identical or functionally identical elements are optionally provided only once with reference numerals. Show it:

• 1 a device for burr-free cutting of a wire in a schematic perspective view;
• 2 a forming unit of the device 1 alone in a perspective view;
• 3 the forming sections of the forming units of the device 1 on a wire in a schematic perspective view;
• 4 a section of the wire 3 after the first forming step and the second forming step in a perspective view in isolation;
• 5 the forming sections of the second forming unit after a tapering of the wire cross section by immersion in the wire (end position) in a sectional view;
• 6 a forming section of the first forming unit of the device 1 in several views;
• 7 a forming section of the second forming unit of the device 1 in several views;
• 8th a separation point of a wire after carrying out the method according to the invention, wherein both resulting wire pieces are shown;
• 9 a further separation point of a wire after carrying out the method according to the invention, wherein only one piece of wire is shown and the wire has a round cross-section; and
• 10 a hairpin;

1 shows a total with the reference numeral 10 designated device for burr-free removal of a wire 12 with square, here rectangular, cross-section (but usually with rounded corners). The device 10 has a first forming unit 14 for forming the wire 12 from two opposite sides, a second forming unit 16 for forming the wire 12 from two other opposite sides and a gripper unit 18 on, by means of the wire 12 can be clamped for pulling separation.

The first forming unit 14 and the second forming unit 16 are on a frame 20 fastened on a mounting plate 22 is mounted. The gripper unit 18 is by means of a tool holder 24 on the receiving plate 22 attached. The receiving plate 22 has several holes (without reference numeral) for attachment of components. In addition, the mounting plate has 22 over recesses 26 for gripping the receiving plate 22 ,

By attaching the forming units 14 . 16 and the gripper unit 18 on the receiving plate 22 forms the device 10 a modular unit 10 , which can be handled as such and, for example, integrated into a longitudinally controlled system with upstream and / or downstream production stations.

The receiving plate 22 is by means of a guide 28 along the wire longitudinal direction X slidably guided. This allows the mounting plate 22 and the components thereon with or relative to the wire 12 along the wire longitudinal direction X be relocated. The wire to the longitudinal direction X parallel movement axis of the receiving plate 22 or the modular unit 10 bears the reference number X ' (Axis of movement X ' ). The leadership 28 has rails 30 and with the rails 30 corresponding weighing 32 on to which the receiving plate 22 is attached. To the receiving plate 22 is also a motor drive 34 coupled, by means of the receiving plate 22 along the wire longitudinal direction X or the movement axis X ' is drivable.

The wire 12 becomes along the wire longitudinal direction X through the device 10 led (in 1 from right to left), with the wire 12 as endless material from a wire roll 36 (Roller shaft 37 ) and the device 10 at an entrance side 38 is supplied.

As already indicated, the device serves 10 for burr-free cutting of a wire 12 with present rectangular cross section and sets this the forming units 14 . 16 and the gripper unit 18 as described below.

The first forming unit 14 serves to reshape the wire 12 with two opposite Umformabschnitten 40 by a tool drive 42 along a first axis of movement Z are simultaneously movable towards each other (see 2 and 3 ). By means of the forming sections 40 can be the wire cross-section of two opposite sides 44 (Narrow sides 44 ) are rejuvenated.

The second forming unit 16 serves to reshape the wire 12 with two opposite Umformabschnitten 46 by a tool drive 48 along a second axis of movement Y are simultaneously movable towards each other (see 2 and 3 ). By means of the forming sections 46 can the wire cross-section of two further opposite sides 50 (Broadsides 50 ) are rejuvenated.

The gripping unit 18 used to pull the wire 12 (please refer 1 ). This can be done by the wire 12 by means of the gripping unit 18 be clamped. For this purpose, the gripping unit 18 two mutually movable jaws 52 with attached wire clamping sections 54 on.

The forming sections 40 the first forming unit 14 and the forming sections 46 the second forming unit 16 are all in a common plane 56 arranged (in 3 indicated). In other words, the tool axes passing through the tool tips are 58 . 60 (parallel to the axes of motion Z and Y ) of the forming sections 40 . 46 (please refer 6 and 7 ) in one plane. Because the forming sections 40 the first forming unit 14 and the forming sections 46 the second forming unit 16 from the first forming step to the second forming step, not relative to the separation point 62 in the wire longitudinal direction X be moved, this is done by a rejuvenation of the wire 12 exactly at the same wire longitudinal position 62 (Separation point 62 ; please refer 4 ). The level 56 is orthogonal to the wire longitudinal direction X oriented and is in 1 vertical, eg. perpendicular to the receiving plate 22 arranged.

As based on 6 and 7 to recognize form the forming sections 40 . 46 each part of a forming tool 41 . 47 , which in each case still a shank 49 . 51 over which the forming tool 41 . 47 can be attached. In the shaft 41 . 47 of the forming tool 41 . 47 can still holes, possibly with thread, be formed (without reference numerals).

The first forming unit 14 and the second forming unit 16 are arranged such that the first movement axis Z and the second movement axis Y orthogonal to each other. These are the forming units 14 . 16 orthogonal to each other on the frame 20 mounted (see 1 ).

2 shows the first forming unit 14 with the forming sections 40 or the forming tool 41 in isolation. The first forming unit 14 has one with the tool drive 42 coupled threaded shaft 64 on, as a ball screw 64 is trained. The thread shaft 64 has two threaded sections 66 . 68 with in the same amount, but oppositely oriented thread pitches on. In each case a forming section 40 or forming tool 41 is with a threaded section 66 . 68 coupled.

The thread shaft 64 is by means of bearing blocks 70 . 72 on a base plate 74 the forming unit 14 attached. The forming sections 40 are over the shaft 49 each on a tool holder plate 78 . 80 are attached. The tool holding plates 78 . 80 are each with a running body 82 . 84 connected, in each case one with the thread shaft 64 corresponding mother 86 . 88 is attached. The nuts 86 . 88 are as spindle nuts 86 . 88 educated. The tool drive 42 , for example as an electric motor 42 trained, is by means of a coupling 90 with the thread shaft 46 coupled.

The second forming unit 16 is analogous to the first forming unit 14 constructed, but has instead of the forming sections 40 or the forming tools 41 the forming sections 46 or the forming tools 47 on.

The forming sections 40 the first forming unit 14 may have a greater width than that through these forming sections 40 reshaped wire sides 44 (Narrow sides 44 ; please refer 3 ). The forming sections 46 the second forming unit 16 may have a greater width than that through these forming sections 46 reshaped wire sides 50 (Broadsides 50 ). It should be noted that the illustration in 3 is schematic and the forming sections 40 . 46 each in their final position in the wire 12 shows, wherein the forming sections 40 . 46 not at the same time, but for reasons of forming successively in the wire 12 penetrate, especially the forming sections 40 . 46 otherwise collide with each other as described above.

In general, the forming sections 40 . 46 each one tapering towards the free end, for example, tapered or chamfered tool tip 92 . 94 on (see 6 and 7 ).

The forming sections 40 the first forming unit 14 have a tool tip 92 with a first wedge angle 96 on and the forming sections 46 the second forming unit 16 have a tool tip 94 on, their wedge angle 98 directly at the tool tip 94 smaller than the first wedge angle 96 , The forming section 40 can one related to the tool axis 58 orthogonal face 93 exhibit. The wedge angle 96 can be, for example, 30 °.

The first forming unit 14 can for a deformation of the wire 12 with a smaller penetration depth (penetration depth, for example, approx. 0.5 mm). That way the wire can 12 for example, from the opposite narrow sides 44 be tailored. Such a transformation can be called "coining". The second forming unit 16 can be used for forming with a higher penetration depth (remaining material thickness between the tool tips 94 in end position, for example, approx. 0.2 mm). Although in this forming no separation, but only a deformation of the Wire material occurs, one could call such a transformation due to the higher than in the "Coining" penetration depth as "cutting".

The forming sections 46 the second forming unit 16 can in non-illustrated embodiments, a tool tip 94 have a continuous wedge angle 98 has (not shown).

Alternatively, the forming sections 46 the second forming unit 16 a tool tip 94 having a plurality of sections with different wedge angles. Here, the wedge angle 98 at the free end of the tool tip 94 smaller than a wedge angle adjoining the side facing away from the free end 100 , Between the wedge angle 98 at the free end and the wedge angle 100 can the forming section 46 a straight-line course 102 exhibit. The wedge angle 98 can be, for example, 15 °. The wedge angle 100 can be, for example, 30 °. The forming section 46 can one related to the tool axis 60 orthogonal face 103 exhibit.

The method for burr-free cutting of the wire 12 with rectangular cross-section runs as follows: First, a burr-free forming of the wire 12 at a wire longitudinal position 62 (please refer 4 ) by simultaneous movement of two opposite Umformabschnitten 40 the first forming unit 14 along the first movement axis Z. In this case, the wire cross-section in this first forming step of two opposite sides 44 tapered ago and it remains a tapered wire cross-section.

Thereafter, a deformation of the wire 12 at the same wire longitudinal position 62 by simultaneous movement of two opposite Umformabschnitten 46 along a second axis of movement Y , In this case, the already tapered wire cross-section in this second forming step of two other opposite sides 50 Tapered ago and the already tapered wire cross-section remains in a further tapered shape. 3 shows this schematic view after performing both forming steps before a tensile separation.

The forming units 14 . 16 lead during the first forming step and the second forming step along the wire longitudinal direction X no relative movement to the wire 12 by. In other words, the relative speed between forming units 14 . 16 and the wire 12 zero.

The first forming step and the second forming step are performed along the wire longitudinal direction X moving wire 12 , wherein the forming units 14 . 16 during the forming steps synchronous with the wire 12 be moved.

Subsequently, a tensile separation of the wire 12 at the same wire longitudinal position 62 by applying an at least partially along the wire longitudinal direction X acting tensile force on the wire 12 , The forming sections 40 the first forming unit 14 and the forming sections 46 the second forming unit 16 they are all in a common plane 50 and are moved in this plane (see 3 ). The first movement axis Z and the second axis of motion Y are oriented orthogonal to each other (see 1 and 3 ).

When forming the wire 12 are the forming sections 40 the first forming unit 14 and the forming sections 46 the second forming unit 16 always spaced from each other. For the forming sections 40 is this based 3 recognizable in which the forming sections 40 . 46 are shown in their maximum approximate end position. For the forming sections 46 this is off 5 recognizable in which the forming sections 46 are shown in the end position (remaining material web between the forming sections 46 visible).

The forming sections 40 the first forming unit 14 and the forming sections 46 the second forming unit 16 each have the same travels and are moved with the same speed in opposite directions. When forming the wire 12 can the forming sections 40 the first forming unit 14 and the forming sections 46 the second forming unit 16 be moved intermittently or continuously.

The wire 12 becomes the forming units 14 . 16 from an input side 38 supplied and by means of a wire guide (not shown) along the wire longitudinal direction or wire passage direction X guided. At an exit side 39 becomes the wire 12 through the gripping unit 18 guided and can be supplied after separation of a further processing. The gripping unit 18 is the forming units 14 . 16 in the wire longitudinal direction or wire passage direction X downstream.

To draw the wire is the wire 12 in the gripping unit 18 clamped and the gripping unit 18 is by driving the receiving plate 22 together with the forming units 14 . 16 relative to the wire 12 emotional. Because the speed of the gripper unit 18 or the receiving plate 22 is greater than the speed of the wire 12 (Relative speed), there is an increasing tensile stress until the wire is torn off 12 at the wire longitudinal position 62 (Separation point 62 ).

After tearing off the wire section (wire rod) becomes the severed part of the wire 12 from the gripper unit 18 kept on. The severed wire section then becomes the gripper unit 18 taken and a next manufacturing station, such as the forming supplied.

After the train separation runs as a unit 10 trained device 10 back in the direction of the wire scroll 36 and synchronizes again to the feed rate of the wire 12 until the trailing wire is in the gripper unit 18 is located and clamped there. Thereafter, the first forming step and the second forming step are analogous as described above.

The return speed or return path of the unit 10 in the direction of the wire scroll 36 are set according to the desired length of the wire rod.

The above-mentioned severed wire section forms a piece of wire 104 which has been separated by the process according to the invention. pieces of wire 104 on both sides of a separation point 62 , which was created by the method according to the invention are in 8th shown the corresponding wire 12 has a rectangular cross-section. 9 shows a single piece of wire 104 with a round cross section which was separated by the process according to the invention.

In the 8th and 9 shown wire pieces 104 are each along a wire longitudinal direction L extends. A radial wire direction R extends orthogonal to the wire longitudinal direction L and forms with a wire circumferential direction U one on the wire 12 or the respective pieces of wire 104 referenced cylindrical coordinate system. In the 8th shown wire pieces 104 have a rectangular cross section. In other words, an original exterior 107 the pieces of wire 104 is, when viewed in a section orthogonal to the wire longitudinal direction L , rectangular. The piece of wire 104 out 9 or its original exterior 107 On the other hand, it has a round cross-section.

The pieces of wire 104 each have a tapered section 106 on top of the original outside 107 of the wire 12 or the piece of wire 104 in the radial direction of wire R is offset inwards. The rejuvenated section 106 has been created in the above-described first and second forming steps.

In the radial direction of wire R inwards, the respective tapered section goes 106 into a fractured surface 108 above. The fracture surface 108 has been created by means of the above-described Zugtrennens.

Because the tapered section 106 , Has been created in the above-described first and second forming steps, he knows a few first radially inwardly sloping surfaces 110 on, which were created by the first forming step, and a few second radially inwardly sloping surfaces 112 created by the second forming step.

The first sloping areas 110 extend from the original outside 107 to the fracture surface 108 , The transition of the first sloping surfaces 110 to the fracture surface 108 gets through a few first transition edges 114 formed, which in the present case are rectilinear. The second sloping areas 112 extend as well from the original outside 107 to the fracture surface 108 , The transition of the second sloping surfaces 112 to the fracture surface 108 is through a few second transition edges 116 formed, which in this case also run straight.

The first transitional edges 114 and the second transition edges 116 in the present case are orthogonal to one another. This orthogonal arrangement of the first transition edges 114 and the second transitional edge 116 is due to the forming steps carried out in the present example and the first and second forming units used in this case 14 . 16 with straight-edged forming sections 40 . 46 and mutually orthogonal extending first and second axes of movement Z , Y conditionally.

10 shows a hairpin made of a piece of wire 104 was made by forming, wherein the piece of wire at its two ends a separation point 62 as in 8th illustrated has.

Claims (21)

Method for burr-free cutting of a wire (12), in particular of polygonal cross-section, characterized by the following steps: - forming the wire (12) at a wire longitudinal position (62) by moving two forming sections opposite each other in a first plane (56) (40) a first forming unit (14) along a first axis of movement (Z), wherein during forming of the wire (12) the forming sections (40) of the first forming unit (14) are always spaced apart, so that the wire cross section in this first forming step two opposite sides (44) is tapered and a tapered wire cross-section remains, - forming the wire (12) at the same wire longitudinal position (62) by moving two mutually opposite in a second plane (56) Umformabschnitten (46) one second forming unit (16) along a second axis of movement (Y), the forming sections (46) of the second forming unit (16) are always spaced apart, so that the already tapered wire cross-section tapers in this second forming step of two other opposite sides (50) ago is and the already tapered wire cross-section remains in a further tapered shape; and - tensile severing of the wire (12) at the same wire longitudinal position (62) with now tapered wire cross section by applying a tensile force to the wire (12). Method according to Claim 1 , characterized in that the first plane (56) and the second plane (56) are congruent. Method according to Claim 1 or 2 , characterized in that the first movement axis (Z) and the second movement axis (Y) are oriented orthogonal to each other. Method according to one of the preceding claims, characterized in that the forming sections (40) of the first forming unit (14) and / or the forming sections (46) of the second forming unit (16) are moved in the opposite direction in the respective forming. Method according to one of the preceding claims, characterized in that the forming sections (40) of the first forming unit (14) and / or the forming sections (46) of the second forming unit (16) during the forming of the wire (12) are each moved intermittently or continuously. Method according to one of the preceding claims, characterized in that the wire (12) the forming units (14, 16) supplied from an input side (38) and guided by a wire guide along a wire feed direction (X). Method according to one of the preceding claims, characterized in that the wire (12) is clamped in a gripper unit (18) for traction separation, and during traction separation the gripper unit (18) is moved relative to the wire (12). Method according to one of the preceding claims, characterized in that the forming units (14, 16) during the first forming step and / or the second forming step along the wire longitudinal direction (X) perform no relative movement to the wire (12). Method according to one of the preceding claims, characterized in that the first forming step and / or the second forming step take place along the wire longitudinal direction (X) moving wire (12), wherein the forming units (14, 16) moves synchronously with the wire (12) become. Method according to one of the preceding claims, characterized in that the forming sections (40, 46) of the first forming unit (14) and / or the second forming unit (16) have a greater width than the respective by these forming sections (40, 46) respectively transformed wire sides (44, 50). Device (10) for burr-free cutting of a wire (12) with polygonal cross-section, with a first forming unit (14) for forming the wire (12) with two mutually opposite each other in a first plane (56) and a tool drive (42) along a first Movement axis (Z) to each other movable forming sections (40), wherein the forming unit is formed such that during forming of the wire (12) the forming sections (40) of the first forming unit (14) are always spaced from each other, so that during forming by means of the forming sections (40) the first forming unit (14) can taper the wire cross section from two opposite sides (44) to a tapered wire cross section; with a second forming unit (16) for forming the wire (12) with two mutually opposite in a second plane (56) and by a tool drive (48) along a second axis of movement (Y) to be moved forming sections (46), wherein the forming unit is formed such that during the forming of the wire (12) the forming sections (40) of the first forming unit (14) are always spaced apart, so that during forming by means of the forming sections (40) of the first forming unit (14) of the already tapered wire cross section of two further opposite sides (50) can be tapered to further tapered shape; and with a gripper unit (18), by means of which the wire (12) can be severed, characterized in that the forming sections (40, 46) of the first forming unit (14) and / or the second forming unit (16) have a greater width than the wire sides (44, 50) to be reshaped by these forming sections (40, 46). Device according to the preceding claim, characterized in that the first plane (56) and the second plane (56) are congruent. Device according to one of the two preceding claims, characterized in that the first forming unit (14) and the second forming unit (16) are arranged such that the first movement axis (Z) and the second movement axis (Y) are oriented orthogonal to each other. Device according to one of the three preceding claims, characterized in that the first forming unit (14) and / or the second forming unit (16) each having a with the tool drive (42, 48) coupled threaded shaft (64) / having two threaded portions ( 66, 68) with the same amount, but oppositely oriented thread pitches, wherein in each case a forming section (40, 46) with a threaded portion (66, 68) is coupled. Device according to one of the four preceding claims, characterized in that the forming units (14, 16) and / or the gripper unit (18) on a receiving plate (22) are arranged and fixed, in particular wherein the receiving plate (22) by means of a guide (28 ) is displaceably guided along the wire longitudinal direction (X) by means of which the receiving plate (22) in the wire longitudinal direction (X) can be driven. Device according to one of the 5 preceding claims, characterized in that the forming sections (40, 46) of a forming unit (14, 16) have a tool tip (92) with a first wedge angle (96) and that the forming sections (40, 46) of the other Forming unit (14, 16) have a tool tip (94) whose wedge angle (102) at least directly to the tool tip (94) is smaller than the first wedge angle (96). Device according to one of the preceding claims, characterized in that the forming sections (40, 46) of a forming unit (14, 16) have a tool tip (94) which has a continuous wedge angle or which has a plurality of sections with different wedge angles (98, 100, 102), wherein the wedge angle (100) at the free end of the tool tip (94) is smaller than a subsequent wedge angle (98) at the side facing away from the free end. A polygonal cross-sectioned wire piece (104) severed from a wire (12), said wire piece (104) having a tapered portion (106) created by plastic forming facing an original outer surface (107) of said wire (12) in FIG a radial wire direction (R) is inwardly offset and merges into a fracture surface (108) created by draft separation, wherein the tapered portion (106) has a pair of first radially inwardly sloping surfaces (110) and a pair of second radially inwardly sloping surfaces (FIG. 112), wherein the transition of the first sloping surfaces (110) to the fracture surface (108) is formed by a pair of first transition edges (114) and the transition of the second sloping surfaces (112) to the fracture surface (108) by a pair of second transition edges (108). 116), wherein the first transition edges (114) and the second transition edges (116) are rectilinear and orthogonal to each other sin d, wherein the distance between the two first transition edges (114) is greater than the distance between the two second transition edges (116) to each other. The wire piece (104) of the preceding claim, wherein the tapered portion (106) has a first radially inwardly sloping surface (110) and a second radially inwardly sloping surface (112), the transition of the first sloping surface (110) to the first Fracture surface (108) is formed by a first transition edge (114) and the transition of the second sloping surface (112) to the fracture surface (108) by a second transition edge (116) is formed, wherein the first transition edge (114) and / or the second Transition edge (116) is rectilinear. A piece of wire (104) according to any one of the preceding claims, wherein the first transition edge (114) and the second transition edge (116) are rectilinear and orthogonal to one another. Hairpin (120) by forming a piece of wire (104) according to one of Claims 18 to 20 was brought into its hairpin shape or by forming a wire (12) was formed and then by means of a method according to one of Claims 1 to 10 or using a device according to one of Claims 11 to 17 was separated from the rest of the wire (12).

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