Device for feeding an elongated workpiece to a forming machine

Abstract

A device (300) for feeding an elongated workpiece (110) to a forming machine (200), which has a feed device (210) that can be operated at a variable feed rate for drawing in the fed workpiece and for conveying the workpiece to a tool area (220) of the forming machine, comprises a receiving device for receiving a workpiece supply (112) in the form of a coil and a first compensation device (360-1) with a movable first deflection unit (340-1), which is directly downstream of the receiving device and can be deflected automatically from a neutral position (343-1) into a tension-dependent compensation position depending on a workpiece clamping force acting in the area of ​​the first deflection unit against a restoring force of a first restoring system (344-1).Furthermore, a second compensating device (360-2) is provided, which is directly downstream of the first compensating device (360-1) and has a movable second deflection unit (340-2), which, depending on a workpiece clamping effect in the area of ​​the second deflection unit, can be deflected from a neutral position (343-2) into a compensating position against a restoring force of a second restoring system (344-2).

Description

FIELD OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to a device for feeding an elongated workpiece to a forming machine.

[0002] Forming machines are machine tools that, with the aid of suitable tools, can produce small or large series of shaped parts, sometimes with complex geometries, from elongated workpieces such as wire, tube, strip, or the like in an automated manufacturing process, predominantly by forming. A processing machine in the form of a forming machine can, for example, be a bending machine for producing two-dimensionally or three-dimensionally bent parts from wire, strip, or tube material by bending, a straightening machine for straightening workpieces, a nailing machine, or a spring manufacturing machine for producing compression springs, tension springs, torsion springs, or other spring-like shaped parts by spring winding or spring coiling.For the efficient production of large quantities of molded parts, highly productive computer-numerically controlled forming machines with numerous machine axes are used today, which are controlled in a coordinated manner via a control device.

[0003] In the production of formed parts from wire, the wire is drawn or fed from a workpiece supply to the tool area of ​​the forming machine using a feed device on the forming machine, controlled by an NC program. The workpiece supply is provided in the form of a coil, which is usually held in a holding device. The term "coil" here refers to a wire bundle wound like a spool. The workpiece supply is held in a device assigned to the forming machine for feeding an elongated workpiece to the forming machine. This device is also referred to as a feed device for short. The fed wire is formed into the desired formed part by the forming tools arranged downstream in the material feed direction.Typically, after all steps of a forming operation have been completed, the finished part is separated from the supplied wire using a cutting device controlled by the NC control program. This process is repeated cyclically for each part to be produced.

[0004] A key task of the feeder is to feed the workpiece material to the forming machine or its feed device at a suitable speed profile. This can be a technical challenge, especially in highly dynamic forming machines that operate with intermittent feed and / or with highly fluctuating feed speeds and strong accelerations.

[0005] Strong accelerations can occur, for example, when the feed device starts up from a standstill or when the fed workpiece material must be decelerated sharply for the cutting operation after completion of a forming operation, sometimes to a standstill. This places high dynamic demands on the unwinding of the workpiece material from the coil. This involves conflicting requirements: on the one hand, the sometimes required high accelerations (positive and negative accelerations) at the feed device of the forming machine, and on the other hand, the restraining forces on the coil side.

[0006] In many cases, the coil is picked up in a receiving device with a (rotating) coiler. Despite the sometimes high accelerations required at the infeed of the forming machine, the coiler should run as smoothly as possible to ensure continuous discharge of the workpiece material (i.e., in particular, without downtime). Attempts have long been made to compensate for existing irregularities in the material discharge by using movably mounted deflection units, such as deflection rollers and / or pivoting arms or similar.

[0007] DE 10 2010 012 263 B3 describes a device for controlling the drive of a reel which carries a wire supply in the form of a coil deposited on the reel, from which the wire is fed to a feed device of the wire feeder of a downstream wire processing machine with the interposition of a tensioning device which is spring-loaded in a deflection direction and effective up to a maximum deflection in order to keep the wire tension approximately constant.

[0008] DE 10 2010 047 531 B4 describes a device for feeding wire to wire processing machines, in which the wire is drawn off from a reel that holds a wire coil and is rotatable about an axis, and is fed to a wire feeder upstream of the wire processing machines. At least one wire deflection device is arranged downstream of the reel in the wire draw-off direction, via which the wire drawn off from the reel is guided and delivered to the wire feeder. A wire storage device is arranged upstream of the wire feeder, which defines a guide track forming a closed circuit, along which the wire runs and whose diameter can be varied between a smaller value, corresponding to an inner radial position of the guide track, and a larger value, corresponding to the outer radial position of the guide track, wherein the guide track is spring-loaded in the direction of assuming the outer radial position.

[0009] DE 10 2019 216 498 A1 discloses a feeding device having an auxiliary feed device downstream of the receiving device, which is drivable by means of an auxiliary drive and configured to convey the workpiece at a predeterminable conveying speed to a downstream buffer storage device. This buffer storage device has an inlet and an outlet for the workpiece, which can form a workpiece loop of variable length in the buffer storage device between the inlet and the outlet. A sensor system is used to detect the fill level of the buffer storage device and to generate sensor signals representing the fill level. A control device of the device is configured such that the conveying speed of the auxiliary feed device can be controlled depending on sensor signals from the sensor system.In one embodiment, a tension compensation device with a movably mounted deflection device is connected downstream of the reel, which is pre-tensioned in a clamping configuration to maintain workpiece tension. TASK AND SOLUTION

[0010] It is an object of the invention to provide a device for feeding an elongated workpiece to a forming machine, which is suitable for feeding the workpiece to the feed device in a suitable state of movement even with high dynamics of processing in the forming machine in trouble-free operation and for avoiding excessive tensile stresses and stress drops on the workpiece.

[0011] This object is achieved by a device having the features of claim 1. Advantageous further developments are specified in the dependent claims. The wording of all claims is incorporated into the description by reference.

[0012] The device is designed for feeding an elongated workpiece to a forming machine, which has a feed device operable at a preset feed speed for drawing in the supplied workpiece and conveying the workpiece to a tool area of ​​the forming machine. The forming process thus works from a workpiece supply in the form of a coil, i.e., a wound wire bundle. Successive workpiece sections of the workpiece are gradually drawn from the workpiece supply and further processed in the forming machine.

[0013] The device comprises a receiving device for receiving a workpiece supply in the form of a coil. The receiving device can be equipped with a reel that is mounted for rotation about a reel rotation axis. The receiving device can also be designed to receive an interchangeable reel and mount it for rotation about a reel axis. The reel serves as a winding aid and unwinding aid and can, for example, have a cylindrical, coil-shaped, or cross-shaped structure and support the wire-shaped workpiece in coiled form. A receiving device can also comprise a different type of device suitable for receiving a coil, for example, a container that can be designed like a barrel.

[0014] The device further comprises a first compensation device with a movably mounted first deflection unit, which is located directly downstream of the receiving device or the workpiece supply and can be automatically deflected from a neutral position into a tension-dependent compensation position, counter to a restoring force of a first restoring system, depending on a workpiece clamping acting in the area of ​​the first deflection unit. In the area of ​​a deflection unit, the direction of travel of the workpiece material changes, so that the outflow direction differs from the inflow direction.Such a first compensation device with a deflectable deflection unit, assigned to the receiving device, can help prevent critically high workpiece tensions, i.e., critical stress peaks. When deflected from the neutral position, it also provides a degree of length compensation. This ensures that strong fluctuations in the tensile forces acting on the workpiece downstream of the first compensation device only have a reduced effect on the workpiece supply, e.g., on a reel. This allows for smoother material removal from the coil. Due to its dual function, the compensation device can also be referred to as a tension and length compensation device.

[0015] The neutral position of the first deflection unit is the position it assumes under the action of the restoring force when there are no counterforces caused by the workpiece. The extent of the deflection depends on the local workpiece tension in the area of ​​the first deflection unit, in the sense that there is a detectable functional relationship between the workpiece tension and the extent of the deflection.

[0016] A special feature of the device according to the claimed invention is that it also has a second compensating device, which is arranged directly downstream of the first compensating device and has a movably mounted second deflection unit, which can be deflected from a neutral position into a compensating position against a restoring force of a second restoring system depending on a workpiece clamping effective in the region of the second deflection unit. The second compensating device is arranged, viewed in the workpiece conveying direction, between the first compensating device and the feed device or the forming machine equipped therewith. It can also be referred to as a machine-side compensating device.

[0017] The second compensation device also has a dual function: on the one hand, tension peaks are buffered by tension-dependent deflection of the second deflection unit and, on the other hand, a length compensation can be created that depends on the extent of the deflection.

[0018] The wording that the second compensation device is "immediately" downstream of the first compensation device means that there is a direct coupling between the exit side of the first deflection unit and the entry side of the second deflection unit, mediated via the clamped workpiece, transmitting tensile forces. The tensile force at the exit of the first deflection unit corresponds in magnitude to the tensile force at the entry of the second deflection unit. In particular, there is no feed device between the first deflection unit and the second deflection unit that acts on the workpiece material and would thus forcefully decouple the exit side of the first deflection unit from the entry side of the second deflection unit.

[0019] Preferably, the deflection movement of the first deflection unit and / or the deflection movement of the second deflection unit is a guided movement, so that the deflection movement proceeds in a controlled manner along a predetermined movement path. For this purpose, a linear guide can be provided, for example, which predetermines a rectilinear movement path. Accordingly, according to a further development, the device comprises a first guide device, in particular a linear guide, for guiding a deflection movement of the first deflection unit and / or a second guide device, in particular a linear guide, for guiding a deflection movement of the second deflection unit. This can support particularly trouble-free operation.

[0020] Preferably, the workpiece material is freely and linearly tensioned between the exit of the first deflection unit and the inlet of the second deflection unit; if necessary, at least one deflection roller that does not change the workpiece tension or another low-friction deflection unit can be interposed in order to change the orientation of the workpiece material between the first and the second deflection unit.

[0021] The first and second compensating devices are therefore force-coupled devices that react as an overall system (compensating system). The device thus has a compensating system with a compensating device arranged close to the workpiece supply in the direction of material flow and another compensating device arranged closer to the downstream forming machine, which are force-coupled via the workpiece material running between the first and second deflection units. It has been found that implementing this concept can achieve numerous advantages, including optimized feed behavior. On the workpiece supply side, cushioning of the tightening torque results in smoother tightening and, associated with this, improved protection of the workpiece material and feed devices.Furthermore, compared to conventional devices, vibrations of the workpiece material between the forming machine and the workpiece storage are reduced. By connecting (at least) two compensation devices directly in series, an improved force distribution between the workpiece storage or holding device and the forming machine can be achieved. Negative slippage effects can be reduced because the resistance during acceleration of the feed device is lower compared to the state of the art. In general, lower stress peaks result due to lower fluctuations in the feed force. All of these advantages can contribute to improving the quality of the produced components, particularly with regard to improved length tolerance.

[0022] According to a further development, at least one of the deflection units is designed as a deflection pulley. Preferably, both deflection units are deflection pulleys with a fixed diameter. The term "deflection pulley" here refers to a force converter with a wheel or the like, which is mounted for rotation with as little friction as possible, serves to guide the workpiece material and to change the direction of a tensile force (the force vector) without changing the magnitude of the tensile force. This largely eliminates friction losses during deflection, since the deflection pulley rolls along the conveyed workpiece material. Alternatively, a deflection unit can take the form of a curved sliding guide in which the workpiece material slides during advance. Instead of a single deflection pulley, a guide curve with several (e.g., five) small rollers can also be provided, which, if necessary, spans a 180° curve in a more or less U-shaped manner or a curve over a somewhat smaller angular range (e.g., 150° to 180°).

[0023] According to a further development, the device is designed to feed the workpiece to the forming machine along a feed direction, and the second deflection unit is mounted in such a way that the second deflection unit can be deflected along a second deflection direction which is oriented parallel or substantially parallel to the feed direction. This results in a strong direct coupling between the tightening torques or pull-in torques of the feed device and the resulting deflection of the second deflection unit, whereby the latter can particularly effectively counteract the resulting stress peaks through possibly greater and faster length compensation. The second deflection unit can, for example, be guided in a linear guide which is oriented parallel to the feed direction or at an acute angle to it (e.g. less than 30° or less than 20° deviation from the feed direction). The second deflection unit can also be designed differently.

[0024] It is possible for the neutral position of the second deflection unit to be an end position of the deflection range remote from the machine, so that deflection only occurs when the tensile forces caused by the draw-in device are greater than the counterforces acting on the part of the first compensation device. According to a further development, however, the return system of the second deflection unit is designed as a bidirectional return system in such a way that the second deflection unit can be deflected in two opposite directions starting from the neutral position. In this case, the neutral position is assumed when there is a force equilibrium between the forces acting in the direction of the draw-in device and the forces acting in the opposite direction. Thus, the second compensation device can act in both cases of a force imbalance in the area of ​​the second deflection unit in the sense of reducing stress and equalizing length.The second compensation device can, among other things, at least partially compensate for the cushioning of the tightening torque of the feed device during acceleration of the feed. During a return movement after deflection, the second deflection unit can initially swing back beyond the neutral position and then gently settle into the neutral position or close to it. A hard stop is avoided. The same can apply if, for example, during the start-up phase of the feed, workpiece material is abruptly supplied by the approaching reel, causing the initially deflected second deflection unit to quickly move back.

[0025] If required, the return system of the first deflection unit can alternatively or additionally be designed as a bidirectional return system.

[0026] According to a further development, the restoring force generated by the first restoring system and / or the second restoring system is adjustable, preferably continuously adjustable. This allows the response behavior of the feed device to be easily adapted to the properties of the workpiece material to be conveyed.

[0027] According to a further development, the first deflection unit is mounted in such a way that the first deflection unit can be deflected along a first deflection direction that is oriented transversely, in particular perpendicularly, to the second deflection direction. An advantage of this configuration is the small space requirement. If necessary, it is possible to stack additional deflection rollers one above the other to increase the buffer storage capacity.

[0028] In preferred embodiments, the spring forces on the upper deflection pulley are greater than on the lower deflection pulley. The spring forces on the upper deflection pulley are preferably greater, among other reasons, because gravity or the dead weight of the wire material must also be compensated for. Larger spring forces at the top are also preferred because the wire is received from the spool in an "unsprung" state. The lower deflection pulley, on the other hand, receives the wire material in a "sprung" state from the upper deflection pulley. The spring forces can be adjusted depending on the workpiece. The smaller the profiles being processed, the smaller the restoring forces on the upper deflection pulley are.

[0029] In many embodiments, the first compensation device comprises a first sensor system with at least one sensor for detecting the deflection of the first deflection unit. In embodiments with a reel drive, this sensor system can be part of a control loop for regulating the reel speed. The rotation of the reel can be controlled depending on sensor signals from this sensor.

[0030] In advantageous embodiments, the second compensation device comprises a second sensor system with at least one sensor for detecting the deflection of the second deflection unit, and a control unit of the device is configured to receive sensor signals from the first and second sensor systems and process them jointly to control the operation of the device. In particular, this allows a reel drive to be even better adapted to the feed behavior of the forming machine with regard to its speed profile. It is also possible to provide only a second sensor system, whose signals are processed to control the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Further advantages and aspects of the invention emerge from the claims and from the description of embodiments of the invention, which are explained below with reference to the figures. Fig. 1 shows a schematic side view of a wire processing system 100 according to an embodiment; Figs. 2A, 2B show characteristic reactions of the compensation system to strong fluctuations in the feed during the initial phase of wire feed; Fig. 3 shows corresponding reactions in a reference system according to the prior art; Figs. 4A to 4C show different operating positions of the second deflection unit. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The Fig. 1 shows a schematic side view of a wire processing system 100 according to an embodiment.

[0033] The wire processing system 100 is designed and configured to process elongated workpieces 110 in the form of metallic wires, which are available as a workpiece stock in the form of a so-called coil, i.e., a wire bundle wound like a spool. From the workpiece material, which is originally available in a large length in the workpiece stock, more or less large quantities of similar shaped parts are produced in a forming process in a computer-numerically controlled production process. The shaped parts can be, for example, coil springs, in particular compression springs or tension springs, or also bent parts of other geometries.

[0034] Other types of forming machines can also produce dissimilar molded parts. Molded parts can generally be bent two-dimensionally or three-dimensionally, and possibly even straight (e.g., with straightening machines or bar-forming machines).

[0035] The wire processing system 100 comprises a forming machine 200, which can be designed, for example, as a spring coiling machine for the production of coil springs. Furthermore, a device 300 is provided upstream of the forming machine in the material flow direction for feeding the elongated wire-shaped workpiece material to the forming machine 200. The device 300 is also referred to in this application as feed device 300.

[0036] The forming machine 200 comprises a feed device 210 connected to the control unit 290 of the forming machine. Under the control of an NC control program, the wire 110 is fed by the feed device 300 along a horizontal feed axis or in a feed direction 302 parallel thereto. The wire is fed into the tool area 220 of the forming machine, in which one or more forming tools 222 are arranged. The forming tools arranged downstream in the material feed direction form the fed wire into a coil spring or (in other forming machines) into another formed part. After completion of the forming operation, the finished formed part is separated from the fed wire by means of a cutting device (not shown) under the control of the NC control program. This process is repeated cyclically for each formed part to be produced.

[0037] A straightening unit 280 is arranged upstream of the feed device 210. The straightening unit 280 is mounted on a frame part of the forming machine 200 and comprises two roller straightening devices arranged downstream of one another, each having a number (e.g., from three to nine) of axially parallel straightening rollers. The rotational axes of the straightening rollers of the consecutively arranged straightening devices are aligned orthogonally to one another. The axis positions of the individual straightening rollers are individually adjustable to adjust the effective geometry of the straightening unit.

[0038] The feed device 210 is arranged downstream of the straightening unit 280 in the material flow direction and serves, among other things, to pull the wire material through the straightening unit 280 toward downstream components. In the example, the feed device 210 is designed as a roller feed device and, in other embodiments, can also be designed as a belt feed device or a gripper feed device. The feed device could also be arranged upstream of the straightening unit.

[0039] The wire is advanced to the tool area 220 or drawn in by the feed device 210 according to a speed profile specific to the manufacturing process, with a time-dependent feed speed. For this purpose, the feed device 210 is controlled accordingly.

[0040] One task of the feed device 300 is to feed the wire to the feed device 210 of the forming machine along the feed direction 302 as accurately as possible at any given time and at the speed required at that time. The feed device 300 has its own control unit 390, which communicates with the control unit 290 of the forming machine. The functionalities of both control units can be integrated into a single control unit.

[0041] The feeding device 300 comprises a feeding unit 310. This comprises a receiving device 330 for receiving a workpiece supply in the form of a coil. In the example, the workpiece supply (coil) is held on an interchangeable reel 335, which is held by components of the receiving device 330 mounted on the frame and, when held, is rotatably mounted about a horizontal axis of rotation (reel axis) 336. The bearing does not take place in the area of ​​the reel axis 336; instead, two axially parallel support rollers 332, 333 with horizontal axes of rotation are mounted on a base plate. These support rollers are components of the receiving device 330. The reel is placed on the two support rollers so that the circumference of the disc-shaped side elements of the reel rests on the two support rollers and the position of the axis of rotation in space is fixed. In the example, this is an active reel with its own drive.The reel drive 334 is in drive connection with the front support roller 333 and can drive it under the control of the control unit 390.

[0042] The wire unwound from the workpiece supply is guided toward the forming machine 200 via components of a compensation system 340 and deflected several times, in the example case exactly twice. The compensation system 340 is configured to reduce workpiece stress peaks through compensating movements and to ensure, through variable temporary length compensation, that despite potentially highly dynamic intermittent operation of the feed device 210, no critical stress states and / or critical vibrations occur on the workpiece, and that smooth operation of the reel 335 is guaranteed.

[0043] The compensation system 340 of the exemplary embodiment is constructed exclusively with passive components, thus requiring no electrically or otherwise controllable actuators and is, for this reason among others, very robust and cost-effective.

[0044] The compensating system 340 comprises a first compensating device 360-1 with an upper deflection pulley 340-1 and a second compensating device with a lower deflection pulley 340-2. The deflection pulleys, designed in the manner of spoked wheels with low inertial mass, are arranged vertically one above the other on a vertical support 341 with mutually parallel axes of rotation. Both have a circumferential guide groove and a fixed diameter, which can be, for example, in the range from 80 mm or 100 mm to 600 mm, so that the wire experiences no or at most uncritically slight plastic deformation during deflection. The deflection pulleys have identical diameters, but different diameters can also be provided. In principle, the diameters of the reel wheels or deflection pulleys should be of a similar order of magnitude to that of the spool used.

[0045] The workpiece (the wire) is guided from the coil over the top side of the upper deflection roller 340-1, wraps around it over slightly less than half its circumference (approximately 160° to 170°), and runs vertically downwards from the outlet of the upper deflection roller to the inlet of the lower deflection roller 340-2. The lower deflection roller 340-2 is wrapped around approximately three-quarters of its circumference in such a way that the outlet, i.e. the top side of the lower deflection roller 340-2, is at the level of the inlet opening of a straightening unit 280. The wire is therefore guided from the lower deflection roller essentially along the horizontal feed direction 302 coaxial with a horizontal feed axis to the inlet opening of the straightening unit 280 or in the direction of the feed device 210.

[0046] The upper deflection roller 340-1 is designed as a vertically movable dancer roller with spring return. For this purpose, the axis of the upper deflection roller is mounted in a bearing element that is guided for linear movement in a vertically aligned upper linear guide 350-1 on the support 314. An elastic return system 344-1 with one or more springs preloads the linearly guided bearing element toward an upper end position of the linear movement determined by a stop. This end position corresponds to the neutral position 343-1 of the upper deflection roller 340-1, which is automatically assumed in the absence of external forces or when the workpiece is only slightly clamped.If the workpiece tension of the workpiece guided over the first deflection roller 340-1 exceeds a predeterminable limit value, the upper deflection roller 340-1 is deflected downwards against the spring force of the return system, which results in tension compensation (reduction of the workpiece tension) and length compensation (shortening of the path length between the reel and the second deflection roller).

[0047] By sensing the position of the upper deflection roller 340-1, the drive motor 334 for the support / drive roller is controlled. The payoff speed of the reel is increased when the upper deflection roller is deflected downward from its neutral position.

[0048] The lower deflection roller 340-2 is designed as a horizontally movable roller with bidirectional spring return. As can be clearly seen in Figs. 4A to 4C, the axis of the lower deflection roller 340-2 is mounted in a bearing element 342-2, which is guided for linear movement in a horizontally aligned lower linear guide 350-2 on the support 341. This linear deflection is limited by stops between a front end position (closer to the forming machine) and a rear end position (further away from the forming machine).

[0049] A bidirectional elastic return system 344-2 with springs 346A, 346B on opposite sides of the bearing element 342-2 preloads the linearly guided bearing element into a neutral position 343-2, which is automatically assumed in the absence of external forces or with only slight workpiece clamping (see Figs. 4A and 4C). This neutral position is located at a distance from both end positions, e.g., more or less centrally between the end positions, so that the lower deflection roller 340-2 can be deflected from its neutral position in two opposite directions parallel to the feed direction (horizontal in the example). If the force generated, for example, by the feed device and acting on the bearing element of the lower deflection roller parallel to the feed direction 302 or to the feed axis exceeds the force component acting in the opposite direction on the bearing element, the lower deflection roller 340-2 is deflected in the direction of the feed device, and in the opposite case in the opposite direction.

[0050] The second deflection roller 340-2 is assigned a deflection sensor system with at least one sensor 355 for detecting the deflection, whose sensor signals represent information about the extent of the deflection and its temporal progression. The deflection sensor system can, for example, comprise one or more displacement sensors and / or at least one acceleration sensor. The preferably electrical sensor signals are transmitted wired or wirelessly to the control unit 390 and can be processed by it, for example, to control the drive of the reel.

[0051] The compensation system 340 thus has two compensation devices that are directly coupled to one another by force, namely the first compensation device 360-1 assigned to the receiving device with the vertically movably mounted first deflection roller 340-1, which is directly downstream of the reel 335 and, depending on a workpiece clamping effective in the region of the first deflection roller, can be automatically deflected downwards from a neutral position 343-1 into a tension-dependent compensation position against a restoring force provided by a restoring system 344-1, and the second compensation device 360-2, which is directly downstream of the first compensation device 360-1 and has a linearly horizontally movably mounted second deflection roller 340-2,which, depending on the workpiece tension acting in the area of ​​the second deflection roller, can be deflected from its neutral position 343-2 into a compensation position against a restoring force provided by the restoring system 344-2.

[0052] The direct mechanical coupling between the upper deflection roller 340-1 and the lower deflection roller 340-2 ensures, among other things, that the upper deflection roller 340-1, which is assigned to the reel, is supported by the lower deflection roller in the event of any compensating movements and does not have to react immediately and possibly not to the extent that would be necessary without the deflectability of the lower deflection roller. The arrangement of the lower deflection roller 340-2 with the compensating movement oriented parallel to the feed direction at the level of the feed direction is also particularly advantageous, so that the lower deflection roller 340-2 can react directly to particularly strong accelerations of the feed movement with compensating movements, and the upper deflection roller 340-1 is at least partially decoupled from the consequences of strong accelerations during the feed by the lower deflection roller, which indirectly also results in smoother running of the reel.

[0053] Based on the Fig. 2A, 2B , 3 and 4A to 4C, the characteristic reactions of the compensation system 340 to strong fluctuations in the feed during the initial phase of the wire feed are now explained by way of example. Fig. 3 a reference system according to the state of the art, as described, for example, in the application DE 10 2020 212 480 A1 in connection with the Fig. 2 The upper deflection roller OU is designed as a vertically movable dancer roller with spring return, whereas the lower deflection roller UU is mounted in a carrier-fixed bearing and is not deflectable.

[0054] In an initial position, the reel H is still stationary and therefore not rotating. If the feed of the forming machine is now activated, it demands a requested wire length X in a short time, in the example case. The tensile force exerted on the wire in the feed direction is passed on undiminished by the fixed lower deflection roller UU to the upper deflection roller OU and via this to the reel. The upper deflection roller reacts to the increase in workpiece tension by deflecting downwards from its upper neutral position by a deflection Y, against the force of the return system. The deflection Y of the upper deflection roller corresponds to only a fraction of the total available deflection Z, so that a residual deflection ZY of the upper deflection roller is still available. The total available deflection Z corresponds to a specific length buffer volume, which is provided by the deflectable upper deflection roller.In the example, the Y portion of the deflection is already consumed during the start-up phase, so that, for example, only approximately 70% of the storage volume remains (corresponding to a workpiece length that is approximately twice the still available deflection ZY). The deflection of the upper deflection roller from its upper neutral position generates a start signal via the position measuring system located there, which causes the control unit to initiate the reel rotation in the unwinding direction.

[0055] In comparison, the Fig. 2A und 2B the reactions of the embodiment of the invention with axially deflectable lower deflection roller 340-2 in the same initial situation. Here, too, the reel is initially at a standstill and the feed device of the forming machine starts and requests the wire length X. This is initially provided predominantly by the compensating movement A2 of the lower deflection roller 340-2 in the direction of the feed device, so that the workpiece tension in the area of ​​the upper deflection roller 340-1 increases considerably less than in the reference system. Accordingly, the upper deflection roller is deflected only slightly by the amount Y`. Thus, a large part of the storage volume ZY` provided by the upper deflection roller remains available for further operation.

[0056] The small deflection Y' of the upper deflection roller 340-1 is detected by the sensor system there, which generates a sensor signal that causes the control unit to initiate reel rotation. Accordingly, the small deflection starts the reel drive, and both deflection rollers can return to their neutral positions under the influence of their return systems ( Fig. 2B ). Due to the force coupling of the first compensation system and the second compensation system, the compensation system as a whole reacts much more gently to short-term, strong increases in tightening torque.

[0057] Conversely, if the wire feed is braked sharply, the lower deflection roller 340-2 would be deflected in the opposite direction, so that in this case too, the upper deflection roller is partly decoupled from the change in workpiece tension by the reaction of the lower deflection roller and can react more smoothly.

[0058] The two directly coupled compensation devices of the compensation system 340 allow for a much smoother tightening action on the reel than with the prior art by cushioning the tightening torque through deflection of the lower deflection roller. Therefore, among other things, the workpiece material is not subjected to sudden, strong tensile loads. This results in improved force distribution between the upper and lower deflection rollers. Furthermore, it has been shown that vibrations of the workpiece material between the forming machine and the reel can be significantly reduced compared to conventional systems. Since the overall resistance during acceleration of the feed is lower than with the prior art, errors caused by slippage, such as excessive length deviations in the finished workpieces, can also be avoided.Thus, relatively simple and cost-effective design measures can make a significant contribution to improving workpiece quality, particularly with regard to improved length tolerance.

[0059] There are numerous ways to constructively implement the basic concept of the invention. In the example, the deflectable deflection units (deflection pulleys or deflection wheels) of the two compensating devices are mounted vertically one above the other. This allows the space required on the machine to be kept particularly small. Such vertical arrangements are particularly easy to implement when processing workpiece materials with relatively small wire thicknesses. For larger wire thicknesses, it can be advantageous to mount the two deflection pulleys at the same height, for example with vertically aligned axes of rotation. Support elements can then be provided for the free sections of the workpiece material. In the illustrated embodiment, both deflection units are deflected linearly. This is also not mandatory. It is also possible for the deflection of at least one of the deflection units to include a pivoting movement from a neutral position.

[0060] The linear guide of a deflectable pulley can be designed, for example, as a roller guide, sliding guide, or magnetic guide. A linear guide can include a carriage or trolley that moves along a single rail. If greater load capacities are required, a carriage or trolley can also run on two or more parallel rails.

[0061] In the exemplary embodiments, the return systems both have a very simple design with coil springs (tension springs and / or compression springs). Damping elements can also be provided to prevent adverse vibrations of the return systems without adversely reducing the response time. The selection of sensors for measuring the deflection can be based on practical criteria. The deflection can be measured directly, for example, using a linear position measuring system, which can operate incrementally or absolutely. A position measuring system can also operate indirectly, for example, using a rotary position measuring system, such as a rotary encoder. If necessary, commercially available linear guides with integrated position measuring systems can be used. Different sensor principles can also be used. A sensor can, for example, operate optically, magnetically, inductively, capacitively, or resistively.An optical measuring system can, for example, work with laser radiation.

Claims

1. A device (300) for feeding an elongated workpiece (110) to a forming machine (200), which has a feed device (210) operable at a varying feed speed for drawing in the fed workpiece and for conveying the workpiece to a tool area (220) of the forming machine, comprising: a receiving device for receiving a workpiece supply (112) in the form of a coil; a first compensation device (360-1) with a movably mounted first deflection unit (340-1), which is immediately downstream of the receiving device and, depending on a workpiece clamping effective in the area of the first deflection unit, can be automatically deflected from a neutral position (343-1) into a tension-dependent compensation position against a restoring force of a first restoring system (344-1); characterized bya second compensating device (360-2) which is connected directly downstream of the first compensating device (360-1) and has a movably mounted second deflection unit (340-2) which can be deflected from a neutral position (343-2) into a compensation position against a restoring force of a second restoring system (344-2) as a function of a workpiece clamping effective in the region of the second deflection unit.

2. Device according to claim 1, characterized in that the device (300) is designed to feed the workpiece to the forming machine along a feed direction (302) and that the second deflection unit (340-2) is mounted such that the second deflection unit can be deflected along a second deflection direction which is oriented parallel or substantially parallel to the feed direction (302).

3. Device according to claim 1 or 2, characterized in thatat least one of the return systems, in particular the second return system (344-2), is designed as a bidirectionally effective return system such that the deflection unit (340-2) can be deflected in two opposite directions starting from the neutral position (343-2).

4. Device according to one of the preceding claims, characterized in that the first deflection unit (340-1) is mounted such that the first deflection unit (340-1) can be deflected along a first deflection direction which is oriented transversely, in particular perpendicularly, to the feed direction (302).

5. Device according to one of the preceding claims, characterized in that the first deflection unit (340-1) is deflectable parallel to a first deflection direction and that the second deflection unit (340-2) is deflectable parallel to a second deflection direction oriented orthogonally to the first deflection direction.

6. Device according to one of the preceding claims, characterized in thatthe device comprises a first guide device, in particular a first linear guide (350-1), for guiding a deflection movement of the first deflection unit (340-1) and / or a second guide device, in particular a second linear guide (350-2), for guiding a deflection movement of the second deflection unit (340-2).

7. Device according to one of the preceding claims, characterized in that the first deflection unit is designed as a first deflection roller and the second deflection unit as a second deflection roller, the first and the second deflection roller are arranged one above the other with mutually parallel axes of rotation such that the first deflection roller is arranged above the second deflection roller, a workpiece section can be guided substantially vertically from an exit side of the first deflection roller to an entry side of the second deflection roller and can be delivered in a substantially horizontal direction over approximately three-quarters of the circumference of the second deflection roller.

8. Device (100) according to one of the preceding claims, characterized in that one or more of the following conditions apply: the first deflection unit is designed as a first deflection roller (340-1) with a fixed diameter; the second deflection unit is designed as a second deflection roller (340-2) with a fixed diameter; the receiving device has a reel (335) which can be driven in rotation about a reel axis (336) by means of a reel drive (334).

9. Device (100) according to one of the preceding claims, characterized in thatthe first compensating device (360-1) has a first sensor system with at least one sensor for detecting the deflection of the first deflection unit (340-1), the second compensating device (360-2) has a second sensor system with at least one sensor (355) for detecting the deflection of the second deflection unit (340-2), and a control unit (390) of the device is configured to receive sensor signals from the first and second sensor systems and to process them jointly to control an operation of the device (300), in particular to regulate a reel speed.

10. Device (100) according to one of the preceding claims, characterized in that the restoring force of the first restoring system and / or the restoring force of the second restoring system is adjustable, preferably continuously adjustable.

11. Device (100) according to one of the preceding claims, characterized in thatthe restoring force of the first restoring system is greater than the restoring force of the second restoring system.

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