WO2020224977A1

WO2020224977A1 - Method and device for feeding an elongate workpiece to a forming machine

Info

Publication number: WO2020224977A1
Application number: PCT/EP2020/061333
Authority: WO
Inventors: Uwe-Peter Weigmann; Jürgen Wolf
Original assignee: Wafios Aktiengesellschaft
Priority date: 2019-05-07
Filing date: 2020-04-23
Publication date: 2020-11-12
Also published as: EP3965972B1; EP3965972A1

Abstract

In a method for feeding an elongate workpiece, e.g. a wire (110), to a forming machine (200), the forming machine has a draw-in device (210) for drawing in the fed workpiece and for conveying the workpiece to a tool region (220) of the forming machine, which draw-in device can be operated at varying draw-in speed. A workpiece store (112) is provided in the form of a coil. Workpiece portions are led from the workpiece store to an auxiliary draw-in device (330). The auxiliary draw-in device (330) is driven by means of an auxiliary drive (335) and conveys the workpiece at a specifiable conveying speed into a downstream buffer (350). The workpiece (110) forms a workpiece loop (115) of variable length in the buffer (350), between an inlet (352) and an outlet (354) of the buffer, and is led from the outlet (354) of the buffer (210) to the draw-in device of the forming machine. The degree of filling of the buffer (350) is sensed by means of a sensor system (370). The conveying speed of the auxiliary draw-in device (330) is controlled in accordance with sensor signals of the sensor system.

Description

Method and apparatus for feeding an elongate workpiece to a

Forming machine

AREA OF APPLICATION AND STATE OF THE ART

The invention relates to a method and a device for feeding an elongated workpiece to a forming machine.

Forming machines are machine tools which, with the help of suitable tools, can produce smaller or larger series of molded parts with sometimes complex geometry predominantly by forming from elongated workpieces such as wire, tube, strip or the like in an automatic manufacturing process. A processing machine in the form of a forming machine can be, for example, a bending machine for producing two-dimensional or three-dimensional bent parts from wire material, strip material or pipe material by bending, a straightening machine for straightening workpieces, a nailing machine or a spring production machine for the production of Acting compression springs, tension springs, leg springs or other spring-like molded parts by means of spring coils or spring coils. For the efficient production of large numbers 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.

In the manufacture of molded parts from wire, the wire is drawn in or conveyed from a workpiece supply to the tool area of the forming machine under the control of an NC control program by means of a feed device of the forming machine. The workpiece supply is provided in the form of a coil, which is normally accommodated in a receiving device. The term “coil” here refers to a wire bundle wound up like a coil. The stock of workpieces is kept in a device assigned to the forming machine for feeding an elongated workpiece to the forming machine. The feed wire is formed into the desired molded part by the forming tools connected downstream in the material conveying direction. After completion of a forming operation, the finished molded part is cut from the supplied wire by means of a cutting device under the control of the NC control program. This process is repeated cyclically for each molded part to be manufactured. An essential task of the device for feeding the elongated workpiece from the workpiece supply to the feed device of the forming machine is to feed the workpiece material to the forming machine or its feed device in a suitable speed profile. This can be a technical challenge, especially with highly dynamic forming machines that work with intermittent feed and / or with strongly fluctuating feed speeds and strong accelerations.

Strong accelerations can occur, among other things, if the workpiece material supplied for the cutting operation has to be braked sharply after a forming operation has been completed, sometimes to a standstill. This creates high dynamic demands on the unwinding of the workpiece material from the coil. There are contradicting requirements here, namely on the one hand the high accelerations (positive and negative accelerations) required at the feed device of the forming machine, on the one hand, and retaining forces on the coil side, on the other

In many cases the coil is picked up in a pick-up device with a (rotatable) reel. Despite the sometimes required high accelerations at the infeed of the forming machine, the reel should run as smoothly as possible in order to be able to deliver the workpiece material continuously (i.e. in particular without standstill). Attempts have been made for a long time to compensate for existing non-uniformity in the material withdrawal using movably mounted deflection devices and / or pivot arms or the like.

For example, DE 10 2010 047 531 B4 describes a device for feeding wire to wire processing machines, in which the wire is withdrawn from a reel that receives a wire coil and rotatable about an axis and is fed to a wire feeder upstream of the wire processing machines. At least one wire deflection device is connected downstream of the reel in the wire withdrawal direction, via which the wire withdrawn from the reel is guided and delivered to the wire draw-in. Upstream of the wire feed is a wire storage device, which provides a guide track that forms a closed circuit, on which the wire runs and whose diameter can be changed 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, whereby the guideway is spring-biased towards taking up the outer radial position. 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, of which the wire is interposed with a resiliently pretensioned in a deflection direction up to a maximum deflection effective tensioning device is fed to a feed device of the wire feeder of a downstream wire processing machine for approximately keeping the wire tension constant. The speed curve of the feed speed of the wire feeder is controlled according to a predetermined speed-time profile by a control of the wire processing machine and the speed curve of the reel according to a predetermined speed-time profile by a drive control of the reel, the drive control of the reel the speed time -Profile of the reel compared to the speed-time profile of the feed speed starts offset by a specified period of time. With this solution, the speed-time profile for the reel control is specified from the start, so that control is no longer carried out as a reaction to a previous behavior of the draw-in movement of the wire draw-in.

DE 44 43 503 A1 describes a method for feeding wire to a forming machine, the wire being unwound from a stored spool or a stored coil and guided in a defined direction. The wire is unwound from an unwinding device in which the bobbin or coil is stored and fed to a separate feed device. The wire is guided in a loop between the unwinding device and the feeding device, the deflection of the loop being determined by a detection unit. In addition to the rotary movement for unwinding, the unwinding device also performs a pivoting movement about the wire feed direction, the amount and direction of which is specified by the detection unit. The method is intended to enable compensation for the twisting of the spring twist, which is particularly important for the processing of spring-hard drawn wire types.

TASK AND SOLUTION

It is an object of the invention to provide a method and a device for feeding an elongated workpiece to a forming machine, which are suitable for always feeding the workpiece to the intake device in a suitable state of motion, even with high dynamic processing in the forming machine.

This object is achieved by a method with the features of claim 1 and by a device with the features of claim 11. Advantageous developments are in the dependent claims. The wording of all claims is incorporated into the content of the description by reference.

According to the method, a workpiece supply is provided in the form of a coil, that is to say a wound wire bundle. Workpiece sections of the workpiece are fed from the workpiece supply to an auxiliary feed device. This supply is preferably carried out continuously, that is to say in particular without a complete standstill.

The auxiliary feed device, driven by an auxiliary drive, conveys the workpiece at a predefinable conveying speed into a downstream buffer store. This is designed in such a way that the workpiece can form a workpiece loop of variable length in the buffer store between an entry and an exit of the buffer store. What is meant here is that the length, measured in the longitudinal direction of the workpiece, of the workpiece section lying between entry and exit in the form of a workpiece loop can vary. The workpiece is guided from the outlet of the buffer store directly or via at least one deflection to the feed device of the forming machine.

The filling level of the buffer storage is recorded by means of a sensor system. The conveying speed of the auxiliary feed device is controlled as a function of sensor signals from the sensor system. The term “filling level” here denotes a ratio between the portion of the buffer memory currently used by the workpiece loop and the total storage capacity of the buffer memory intended for use. The degree of filling depends on the current length of the workpiece in the workpiece loop between an entry and the exit of the buffer store and varies whenever the entry speed at the entry differs from the exit speed at the exit.

A device suitable for carrying out the method for feeding an elongated workpiece to a forming machine comprises, according to one formulation of the invention, a receiving device for receiving a workpiece supply in the form of a coil, and a downstream auxiliary feed device which can be driven by means of an auxiliary drive. The auxiliary feed device is configured to convey the workpiece at a predefinable conveying speed to a downstream buffer store. The buffer store has an inlet and an outlet for the workpiece. The buffer store is designed in such a way that the workpiece can form a workpiece loop of variable length in the buffer store between the inlet and the outlet. The buffer memory includes a sensor system for detecting the filling level of the buffer memory and for generating sensor signals representing the filling level. The controller of the device is such configured so that the conveying speed of the auxiliary intake device can be controlled as a function of sensor signals from the sensor system.

When using the claimed invention, it is possible to always feed the required workpiece material to the feed device of the forming machine in the appropriate state of motion, even if the feed device is operated with strong fluctuations in the feed speed up to stop-and-go operation. It is thus possible to decouple the area in which the workpiece is fed from the area in which the workpiece is processed at the interface between the feeding device and the forming machine so that the workpiece feeding does not impair the processing operations on the forming machine in an uncontrollable manner.

Controllable components of the device for feeding the elongated workpiece, in particular the auxiliary intake device, are preferably controlled in such a way that the workpiece on an entry side of the intake device is either loaded with an essentially constant tensile force or is essentially free of tensile force. In both cases, substantial fluctuations in tensile force are avoided, so there is practically no pulsating tensile force on the intake device. The controlled and possibly complete decoupling of the workpiece supply from the workpiece processing that can be achieved in this way avoids supply-related quality fluctuations in the finished products. For example, fluctuations in the length of the products caused by insufficient supply can be avoided.

In some embodiments it is provided that the receiving device has a reel which can be driven in rotation by means of a reel drive. Furthermore, a voltage equalization device is provided downstream of the reel. This is followed by the auxiliary intake device, which can be driven by means of an auxiliary drive. The tension equalization device has at least one movably mounted deflection which, for example, can be guided in a linearly moveable manner or attached to a swivel arm and is pretensioned in a clamping configuration. The stress equalization device can help to maintain the workpiece stress acting in the longitudinal direction of the workpiece and thereby avoid stress peaks. In addition, a certain length compensation can be effected.

In some embodiments it is provided that the speed of the reel is variably controlled as a function of the position of the deflection device of the tension equalization device. The speed of rotation of the reel can be varied depending on the tension in the workpiece behind it so that the tension is reduced will. If, for example, the workpiece is under strong tensile stress after it has been pulled off the reel, so that the deflection device is displaced against its pretension, the tensile stress can be reduced again. In this way, the voltage compensation device can be designed as a sensor system of a control loop for regulating the reel speed. With the help of suitable sensors, this sensor system can detect the workpiece tension between the reel / coil and the auxiliary feed device and send a sensor signal that is dependent on the workpiece tension to the control unit, which can control the reel drive. For this purpose, the voltage compensation device can have corresponding sensors, for example one or more displacement sensors for detecting the deflection of the deflection device and / or one or more force sensors.

If the reel speed is variably controlled or regulated as a function of the workpiece tension, the method or the device for feeding the elongated workpiece basically comprises two cooperating compensation systems or compensation mechanisms, namely a first compensation system, which can change the reel speed depending on the tensile force, as well as a Second compensation system, which works with the aid of the auxiliary feed device, which can be controlled with regard to the conveying speed, and the associated buffer store.

In other embodiments it is provided that the receiving device has a reel which is rotatably mounted but not driven, that is to say to which no reel drive is assigned. Such a “passive heap” is an inexpensive solution. The rotation is brought about by the wire being drawn off the coil using the auxiliary feed device. Preferably, no voltage equalization device is provided downstream of the (passive) reel, which saves installation space and costs and the auxiliary feed pulls the wire off the reel directly or via a deflection, thereby causing the reel to rotate.

In order to ensure a smooth wire withdrawal under all operating conditions, a braking device is provided in some embodiments with a passive (non-drive) reel to brake the reel rotation when braking or stopping the pull-in movement of the auxiliary pull-in device. The braking device can be designed as a controllable braking device, the braking force of which can be variably controlled via control signals. One example is a pneumatic braking device. The braking device can be controlled, for example, in such a way that a braking intervention takes place when the pull-in movement of the auxiliary pull-in device is slowed down or stops. It is also possible to design the braking device as a passive braking device which, for example, has a permanent Frictional contact increases the moment of inertia or the rotational resistance of the reel, so that its rotation quickly comes to a standstill when the wire tension on the wire take-off device drops.

There are also embodiments without a reel. In some variants, the workpiece stock is provided in the form of a coil or a wire bundle in a container. The receiving device thus has a container for receiving the workpiece supply. Such structurally relatively simple variants can be provided particularly inexpensively. The container does not have to be rotatable, it can be placed firmly on the hall floor or on a separate surface. The container can e.g. be designed as a barrel open at the top into which the coil is placed. The container can have a more or less cylindrical shape, the inner diameter of which is slightly larger than the outer diameter of the largest coil to be accommodated. In contrast to a reel, the workpiece can be gradually withdrawn from the inner circumference of the coil. The coil can rest, so it does not have to be turned. A rotatable mounting of the coil inside the container and / or a rotatable mounting of the container can, however, be provided. Preferably, a lid which is connected by means of a hinge or which can be completely removed is provided for closing the container. In the lid, e.g. in its center, a feed-through opening for passing the withdrawn workpiece sections can be provided. The embodiment with a container, in particular with a barrel, is relatively simple and inexpensive to implement in terms of construction. A wire change requires relatively little effort. If necessary, e.g. the container can easily be exchanged for another container.

There are different options with specific advantages for the design and arrangement of the buffer store.

In some embodiments it is provided that the workpiece forms a free workpiece loop between the entry and exit of the buffer store in such a way that no mechanical deflection takes place between the entry and the exit around which the workpiece has to be guided. The buffer store can be designed, for example, to receive an essentially U-shaped free workpiece loop. The buffer store can therefore be designed in such a way that a free part of the workpiece loop is essentially U-shaped. If a free workpiece loop is formed without mechanical deflection, essentially only the inertial forces occurring on the workpiece itself, possible frictional forces at the boundaries of the buffer memory and / or possibly gravity as resistance to a free change in the filling level of the buffer memory. So there are hardly any uncontrollable secondary forces in connection with the buffer storage. In preferred embodiments, the buffer store comprises a flat storage box which has a cuboid interior space in which the workpiece can form a substantially U-shaped loop between the inlet and the outlet. In this case, legs of the U-shape that are essentially parallel to one another can run parallel to narrow sides of the storage box and can be connected via an arcuate section on the side facing away from the inlet and outlet. A length of the storage box measured parallel to the narrow sides is preferably a multiple of the width of the storage box measured between the narrow sides, in particular at least ten times. A relatively flat, long storage box offers a lot of storage capacity while at the same time requiring little space.

In some embodiments, in particular those with a reel, the buffer store is designed as a horizontal store in such a way that the inlet and the outlet are at the same level. Due to this flat design, a sufficiently high storage capacity can be achieved even with limited installation space. Because the workpiece can form a horizontally lying workpiece loop in the buffer store, no tensile force fluctuations caused by varying weight forces can be introduced even if the loop length varies.

It is also possible for the buffer store to be designed as a vertical store, so that the workpiece loop can hang freely in the buffer store. With this solution, installation space can be saved in terms of width. Even with a vertical storage tank, the inlet and outlet can be at the same height.

In some embodiments, a contribution to avoiding unnecessary inertial forces when feeding the workpiece is made in that the workpiece is guided directly from the outlet of the buffer store in a straight line to the feed device of the forming machine. There is therefore no mechanical deflection between the outlet of the buffer store and the feed device of the forming machine.

It is possible for workpiece sections to run freely in space between functional components of the feed device and / or the forming machine and to be accessible from the outside.

In some embodiments it is provided that workpiece sections of the workpiece in an area between the workpiece supply and the auxiliary intake device and / or in an area between the exit of the buffer store and the intake device by means of a guide device along a guide track that is curved at least in sections. The guide device can, for example, have a tube or a hose for guiding the workpiece sections through. This variant offers many degrees of freedom with regard to the mutual spatial arrangement of the components following one another in the direction of material flow. With the help of a guide hose or a guide tube, a gradual change in the conveying direction in space can be implemented without the need for separate deflection elements such as rollers or the like. must be provided. The receiving device (eg container or reel) can, if necessary, be located relatively far away from the other components, since large conveyor routes can be easily bridged. When the elongated workpiece is guided through a hose or a pipe, no separate safety devices are required to protect the environment and / or the workpiece being conveyed.

The sensor system assigned to the buffer memory for detecting the filling level of the buffer memory can have one or more tactile sensors that respond to contact with the workpiece in the buffer memory. The sensor system preferably works in a contactless manner, for example with the aid of one or more contactless sensors that can work optically, capacitively or inductively, for example. This means that the sensors do not affect the spread of the workpiece loop in the buffer store.

The sensor system is preferably designed in such a way that a multi-stage or continuously operating variable regulation of the conveying speed of the auxiliary intake device is possible. In one embodiment, the sensor system comprises three or more sensors arranged at a distance from one another in the longitudinal direction of the buffer store, which sensors can detect the position of the arcuate section at the bottom of the U-shape in the case of a U-shaped workpiece loop. In addition, sensors can be provided which indicate when a nominal maximum degree of filling or a nominal minimum degree of filling has been reached. Their sensor signals can cause an emergency shutdown of the machine in order to avoid damage to the system due to malfunctions in the workpiece feed.

Elongated workpieces in the form of metallic wire are preferably processed. The invention then also relates to a wire processing system with a wire-processing forming machine, which has a retraction device that can be operated with a varying retraction speed for retracting the fed wire and for conveying the wire to a tool area of the forming machine, as well as a device for feeding the wire to the forming machine according to the claimed invention. The forming machine can be a spring coiling machine, for example. The forming machine can be used, for example, as a bending machine for producing two-dimensional or three-dimensional bent parts from wire material, strip material or pipe material by bending, as a straightening machine for straightening workpieces, as a nailing machine or as a spring production machine for producing compression springs, tension springs, torsion springs or other spring-like molded parts by spring coils or Be designed spring winding.

The components of the feed device are preferably designed exclusively for the material feed and should therefore not cause any permanent (plastic) deformation of the conveyed material. For example, a feeding device contains preferably no straightening unit to straighten the material before it enters the forming machine. All permanent material deformations are implemented in units connected downstream of the deformation machine, which can usually include at least one straightening unit in addition to the feed device. In this way, a clear division of tasks between material supply on the one hand and material forming on the other hand is possible.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and aspects of the invention emerge from the claims and from the following description of preferred exemplary embodiments of the invention, which are explained below with reference to the figures.

1 shows an overall view of a wire processing system with a forming machine in the form of a spring coiling machine and a device connected upstream in the direction of material flow for feeding the elongated wire-shaped

Workpiece material according to an embodiment with a reel for receiving the workpiece supply;

2 shows an overall view of a wire processing system with a forming machine in the form of a spring coiling machine and a device connected upstream in the direction of material flow for feeding the elongated wire-shaped

Workpiece material according to another embodiment with a barrel-shaped container for receiving the workpiece supply;

3 shows an overall view of a wire processing system with a forming machine in the form of a spring coiling machine and a device connected upstream in the direction of material flow for feeding in the elongated wire-shaped Workpiece material according to an embodiment with a non-driven reel in a horizontal orientation.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The schematic FIG. 1 shows an overall view of a wire processing system 100 according to an exemplary embodiment. The wire processing system 100 is set up to produce a large number of similar shaped parts in the form of helical springs, in particular compression springs or tension springs, from an elongated workpiece 110 in the form of a metallic wire in a computer-numerically controlled production process.

The wire processing system 100 comprises a forming machine 200 in the form of a spring coiling machine 200 and a device 300 connected upstream in the material flow direction for feeding the elongated wire-shaped workpiece material to the forming machine. The device 300 is also referred to for short in this application as the feed device 300.

The forming machine 100 comprises a feed device 210, which is connected to the control unit 290 of the forming machine and, under the control of an NC control program, feeds wire, which is supplied by the feed device 300, into the tool area 220 of the Forming machine promotes. The downstream forming tools in the material conveying direction transform the fed wire into a helical spring or (with other forming machines) into another molded part. After completion of the forming operation, the finished molded part is separated from the supplied wire under the control of the NC control program by means of a cutting device (not shown). This process is repeated cyclically for each molded part to be manufactured.

The advance of the wire to the tool area 220 or the drawing-in of the wire by the drawing-in device 210 should take place according to a speed profile specific to the manufacturing process with a drawing-in speed v _E (t) that varies as a function of time. The intake device 210 preferably has at least one pair of intake rollers which has two intake rollers which are arranged with axes of rotation parallel to one another and which can be driven to rotate in opposite directions via a controlled drive. Often two or more pairs of feed rollers that can be operated synchronously are provided in order to be able to transfer the feed forces to the workpiece material in a manner that is gentle on the material and without significant slip. With their profiled circumferential surfaces, the draw-in rollers limit a draw-in gap for the workpiece to be passed through. By controlling the The speed of rotation and the direction of rotation of the feed rollers can thus be specified for the feed speed and the feed direction of the material to be processed.

An inadequately well controlled supply of wire can lead to considerable quality problems, for example in spring coiling machines. In these forming machines, unlike wire bending machines with a bending process, the forming force on the forming tools is applied directly by the feed rollers of the feed device 210 in order to press the workpiece against a winding tool 222 and thus advance the winding process. During this process, any slippage on the intake rollers of the intake device can have a direct impact on the quality of the end product. With highly dynamic spring winch machines, the slip at the draw-in device can, in unfavorable cases, be up to 20% of the total draw-in length, which would make the springs produced too short.

One task of the feed device 300 is to feed the wire to the feed device of the forming machine 200 as precisely as possible at the speed required at this point in 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 the two control units can be integrated in a single control unit.

A workpiece supply with a large length of the wire to be processed is held in the form of a spool or a coil 112 on a receiving device of the device 300. In this example, the receiving device has a reel 310. In the example, the reel is arranged with a vertical reel axis 312 and can be driven to rotate about the reel axis by means of a reel drive 315 that can be controlled by the control unit 390. The wire is then drawn off gradually from the circumference of the coil in the direction of the following devices, while the reel or coil is rotated.

A tension compensation device 320 is connected downstream of the reel. The workpiece 110 is guided from the reel via the tension compensation device 320 to an auxiliary feed device 330, which can be driven with the aid of an auxiliary drive 335 in order to feed the wire under the control of the control unit 390 at a predeterminable conveying speed v _H (t) in the direction of downstream components promote. In the example, the auxiliary intake device 330 has a single intake roller pair which has two intake rollers which are arranged with mutually parallel axes of rotation and which can be driven to rotate in opposite directions with the aid of the auxiliary drive 335. With their profiled circumferential surfaces, the infeed rollers delimit an infeed gap for guiding the wire through and are dimensioned in such a way that they can grip the wire in a non-positive manner and convey it further.

The tension compensation device 320 has a single deflection device 325, around the circumference of which the wire is deflected between the reel 310 and the auxiliary feed device 330, in the example by 180 °. The deflection device 325 can be designed, for example, as a roller or disk, which is mounted in a bearing element so that it can rotate freely about its axis of rotation 326 in order to offer the conveyed wire as little braking resistance as possible. The deflection device can also have an arrangement with a plurality of rollers or discs or the like. The deflection device 325 is guided so as to be linearly movable and, in the example, is pretensioned into a tensioning configuration by means of a spring arrangement 327. Spring arrangement 327 is supported on one side on a fixed bearing fixed to the machine and on the opposite side on the bearing element for the deflection device. The tension compensation device ensures that the wire section between the take-off on the coil 112 and the entry into the auxiliary pull-in device 330 is under slight tensile stress and cannot sag. Other variants work with a pneumatically generated preload.

The movably mounted deflection device 325 functions in the area between the reel 310 or coil and the auxiliary feed device 330 in the manner of a dancer. One function is to achieve a certain length compensation if necessary, namely when the withdrawal speed of the wire from the coil 112 differs from the draw-in speed of the auxiliary draw-in device 330. For example, if the auxiliary pull-in device 330 draws the wire in faster than it is unwound from the circumference of the coil on the reel 310, the dancer (the deflection device) comes under tension and is pulled against the force of the spring arrangement 327, shortening the wire travel path between the reel and the auxiliary pull-in device 330 Pulled towards the fixed bearing, so that tension compensation and length compensation of the path takes place. In the case of reverse speed differences (withdrawal speed from the coil greater than the draw-in speed at the auxiliary draw-in device), the loop guided around the dancer or the deflection device 325 becomes longer, as the rotatable deflection device is pushed further away from the auxiliary infeed by means of the spring arrangement 327. In the example, the voltage compensation device 320 also serves as a sensor system of a control circuit for regulating the reel speed. In principle, this sensor system can detect the wire tension between the reel / coil and the auxiliary draw-in device and output a sensor signal that is dependent on the wire tension to the controller 390 of the feed device. This can change the reel speed based on this. The sensor system can for example have a displacement sensor which emits a sensor signal as a function of the position of the axis of rotation of the deflection device 325 along its guide. Alternatively or additionally, a force sensor can be provided.

The scheme can work as follows, for example. It is assumed that the auxiliary drawing-in device 330 draws the wire in at an almost constant draw-in speed and conveys it in the direction of the downstream components. If the reel 310 rotates too slowly in comparison, the dancer is drawn in against the force of the spring arrangement 327 in the direction of the fixed bearing. The regulation can be configured in such a way that the speed of the reel or of the reel drive is increased when the compensating movement of the dancer exceeds a certain swell path. This means that more wire per unit of time is dispensed from the reel and the difference in speed between

The take-off speed on the coil and the pull-in speed on the auxiliary feed device are reduced.

This first compensation mechanism can in many cases be sufficient in the case of processing processes that are not too dynamic in order to ensure that the wire is fed to the forming machine as required.

The inventors have analyzed the mode of operation and identified operating conditions under which this compensation mechanism alone may not be sufficient. On the one hand, it should be noted that the force with which the deflection device 325 of the

Tension compensation device 320 tensions the wire, depending on the wire diameter and the spring and must be set manually by the machine operator before the start of the forming operation. It requires a lot of experience on the part of the operator to select a sufficiently good setting here. It should also be noted that this subsystem (with reel and tension equalization device) may react too slowly in the case of high dynamic requirements and therefore cannot fully meet the requirements on its own. High dynamic demands on the intake device 210 can arise, for example, when short springs are to be produced in large numbers and / or when the inertia in the area of the reel 310 becomes too great, for example because a very large wire coil is being used. The feed device 300 has a second compensation mechanism which can intervene here and is explained below.

The feed device 300 has a buffer store 350, which is connected downstream of the auxiliary feed device 330 in the wire feed direction. During operation, the auxiliary feed device conveys the workpiece at a predefinable conveying speed v _H (t) into this downstream buffer store. The buffer store has an inlet 352 through which the workpiece coming from the auxiliary feed device 330 enters the buffer store. Furthermore, an outlet 354 is provided, through which the workpiece exits the buffer store in the direction of the following components. Inlet 352 and outlet 354 are arranged on the same side of the buffer store, the direction of entry and direction of exit run parallel to one another.

The buffer store 350 is designed in such a way that the workpiece 110 (the wire) in the buffer store between the inlet 352 and the outlet 354 can form a free workpiece loop 115 of variable length, which largely lies in a single plane. In the example, the buffer store 350 has a relatively flat storage box 355, which has a cuboid interior in which the workpiece can form a substantially U-shaped loop between inlet 352 and outlet 354. The parallel legs of the U-shape run parallel to the narrow sides of the storage box 355 and are connected on the side facing away from the entry and exit via an arcuate section (loop arc). Although the inlet and outlet can lie one above the other, as shown in the schematic figure, it is preferably provided that the buffer store is designed as a horizontally lying flat store so that the entry and exit are at the same height and the workpiece loop is aligned horizontally.

The length of the storage box 355 measured parallel to the narrow sides (in the longitudinal direction L) can be a multiple of the width measured between the narrow sides (in the transverse direction Q) and, for example, more than ten times as large as the width. The slim, flat design of the buffer store 350 or the storage box 355 offers, if required, a high storage capacity while at the same time requiring little installation space.

From the outlet 354 of the buffer store, the wire is guided directly to the inlet side of the draw-in device 210 without any further deflection. Since the wire does not run over a mechanical deflection in the buffer store 350 either, but rather forms a free loop, there is none between the auxiliary feed device 330 and the feed device 210 of the forming machine mechanical deflection. The wire runs in a straight line from the outlet of the buffer store without deflection to the feed device.

It can be seen that the buffer store 350 serves as a buffer for the difference between the generally not constant draw-in speed v _E (t) of the draw-in device 210 and the conveying speed v _H (t) with which the auxiliary draw-in device 330 moves the wire into the buffer store 350 promotes. In the storage box 355 there is a single flat wire loop 115, which becomes larger or smaller depending on the difference between v _E (t) and v _H (t), in such a way that the loop size increases when the auxiliary feeding device increases the amount of wire per unit of time into the buffer store 350 than the intake device 210 conveys out of the buffer store, that is to say at v _H (t)> v _E (t).

The auxiliary intake device 330 is operated in a basic mode in such a way that the speed of the auxiliary intake, ie the conveying speed v _H (t) of the auxiliary intake device, corresponds to the average production speed of the forming machine or the average intake speed of the intake device 210. This speed can be calculated by the control of the forming machine 200 as a function of the production process set up.

The feed device 300 is now able to at least partially compensate for small deviations in the conveying speeds at the inlet and outlet. For this purpose, a sensor system 370 is provided which is set up to detect the current filling level of the buffer memory 350 and to generate sensor signals representing the filling level. The control unit 390 of the device 300 receives these signals and is configured in such a way that the conveying speed v _H (t) of the auxiliary intake device can be controlled as a function of the sensor signals of the sensor system, that is to say can be increased or decreased if necessary.

For this purpose, the sensor system of the exemplary embodiment has four sensors S1 to S4, which are arranged in the longitudinal direction of the buffer store at the same mutual distances from one another. The sensors each work without contact, for example optically, capacitively or inductively, and can query the position of the arcuate loop section within the buffer store. In addition, there is a first emergency stop sensor between these sensors and the entry / exit side, which generates an emergency stop signal to switch off the machine if the wire loop becomes too short, and a second emergency stop on the opposite side -Sensor that triggers a shutdown if the wire loop becomes too long beyond a specified maximum dimension. In this example, the regulation can be configured as follows, for example. When the wire loop 115 or its curved section triggers the sensor S1 furthest from the entry / exit, a control signal is triggered which causes the auxiliary pull-in device 330 to pull in considerably more slowly, i.e., v _H (t) is significantly reduced. The wire loop within the buffer store 350 can then gradually shorten again. If the wire loop sensor S2 triggers, the auxiliary feed will slow down a little less. When the wire loop triggers the sensor S3, the auxiliary feed device 330 is activated in such a way that the auxiliary feed is somewhat faster than the preset average basic speed. If the wire loop triggers the sensor S4, the speed of the auxiliary feed will be considerably faster than the preset average speed.

In this way, a multi-stage, sensitive control of the conveying speed v _H (t) of the auxiliary intake device 330 is implemented with relatively simple, robust means, which reliably prevents overfilling or underfilling of the buffer store 350 and at the same time ensures that the wire of the intake device 210 is always with it the currently required speed v _E (t) is supplied. This enables wire to be drawn into the drawing-in device 210 of the forming machine with almost no tensile force except for friction. With the aid of the feed device 300 it is possible to virtually completely decouple the pulsating feed speed of the forming machine from the possible run-off speeds on the reel 310.

The function or effect of the buffer memory 350 can also be described in other ways. In the case of a comparable arrangement without a buffer store, the uneven draw-in caused by the travel profile of the forming machine, which in some cases can even have a stop-and-go characteristic, is passed on directly to the deflection device or the dancer of the voltage compensation device 320 . This can result in a jolt on the tension compensation device, which in turn can lead to a partially pulsating tensile force within the wire at the machine wire feed, that is to say at the feed device 210. This can lead to quality problems, for example in the form of length fluctuations in the finished springs. With the aid of the interposed wire store (buffer store 350), the possibly pulsating speed of the wire-processing forming machine can be decoupled from the running speed on the wire supply on the reel 310. For this purpose, the auxiliary intake device 330 receives a speed specification from the forming machine, which results in the wire being conveyed at an effective speed by means of the auxiliary intake device. The difference between the retraction speed v _E (t) on the forming machine or its feed device for the effective conveying speed v _H (t) on the auxiliary feed device 330 is compensated for by the loop movement in the storage box 355 of the buffer store. As a result, a wire draw-in at the draw-in device 210 of the forming machine with almost no tensile force (apart from the friction) can be achieved.

Another exemplary embodiment of a wire processing system 400 is described with reference to FIG. 2. The forming machine 200 can be constructed similarly or identically to the forming machine 200 of the first exemplary embodiment and, in the example, is designed as a spring coiling machine with a feed device 210, forming tools 222 and a control unit 290 for controlling the forming machine. For a further description of the forming machine, reference is made to the first exemplary embodiment.

In addition to the forming machine 200, the wire processing system 400 comprises an upstream device 500 in the material flow direction for feeding the elongated wire-shaped workpiece material to the forming machine. This device 500, which is also referred to as a feed device 500, has some differences from the feed device 300 of the first exemplary embodiment.

As in the first exemplary embodiment, there is a workpiece supply with a large length of the wire to be processed in the form of a spool or a coil 412 in or on a receiving device of the device 500. The receiving device comprises a container 410 which essentially has the shape of a cylindrical barrel, the inner diameter of which is somewhat larger than the outer diameter of the largest wire coil to be received. The container stands firmly on the floor or on its own platform and does not require any moving parts. In particular, no rotation of the container and no rotation of the coil are provided during operation.

The barrel-shaped container 410 has a flat bottom and a cylindrical container wall. The container is closed at the top by a removable cover 414, which has a feed-through opening 416 in its center for leading out the wire-shaped workpiece that is to be gradually withdrawn from the coil 412.

In the direction of material flow behind the receiving device with container 410, an auxiliary feed device 430 is provided, which can be driven with the aid of an auxiliary drive 435 in order to feed the wire under the control of the control unit 490 at a predeterminable conveying speed in the direction of downstream components, in particular of the downstream buffer store 450 to promote. The auxiliary intake device 430 can be designed similarly or identically to the auxiliary intake device 330, which is why reference is made to the description there.

The workpiece 110 (the wire) emerges at the top of the container 410 essentially in the vertical direction and enters the auxiliary intake device 430 essentially in the horizontal direction at the entry side of the latter. Between the outlet opening of the container 410 and the inlet of the auxiliary feed device 430, the wire is guided with the aid of a guide device 420 along a more or less continuously slightly curved guide path. In the exemplary embodiment, the guide device comprises a flexible plastic tube which serves as a guide tube for the workpiece material passing through. Due to the flexibility of the hose material, slight compensatory movements of the guide device are possible during operation. Alternatively, e.g. a guide device with (at least) one rigid guide tube can also be provided. The radius of curvature of the most strongly curved sections of the guide device can be so large that the workpiece material can be guided along the curved path with little friction without the risk of plastic deformation.

If necessary, the guide device can be several meters long, so that there is great flexibility with regard to the installation of the container 410 in relation to the mounting position of the auxiliary intake device 430.

In some embodiments e.g. the buffer store 450 and the auxiliary intake device 430 are arranged between the container 410 and the forming machine 200 (cf. FIG. 2). However, it is also possible to arrange the container 410 in a space between the buffer store and the forming machine.

Guide devices of this type, e.g. with a hose or a tube can also be provided in the first embodiment.

Similar to the first exemplary embodiment, the feed device 500 has a buffer store 450 behind the auxiliary intake device 430 in the material flow direction. This is designed in such a way that the workpiece 110 (the wire) in the buffer store between the inlet 452 and the outlet 454 can form a free workpiece loop 115 of variable length, which may be largely in one plane. In contrast to the first exemplary embodiment, the buffer store is designed as a vertical store, the workpiece loop therefore lies essentially in a vertical plane. Entry 452 and the Exit 454 can be at the same level (as in the schematic exemplary embodiment) or at different levels.

From the outlet 454 of the buffer store 450, a guide device 460 in the form of a flexible guide hose or a guide tube leads along an at least partially curved guide path to the inlet of the feed device 210 of the forming machine 200 be bridged, so that a flexible installation of the feed device 500 in relation to the forming machine 200 is possible.

The auxiliary draw-in device 430 conveys the wire at a predeterminable conveying speed v _H (t) in the direction of the downstream buffer store 450 and accordingly pulls the wire off the coil 412 at this speed. The wire material is essentially unwound from the inner circumference of the wire spool and guided through the passage opening 414 in the cover and the adjoining guide device 420 to the auxiliary feed device 430. In a basic mode, the auxiliary intake device is operated in such a way that the speed of the auxiliary intake, that is to say the conveying speed v _H (t), corresponds to the average production speed of the forming machine or the average intake speed of the intake device 210. The feed device 500 is able to at least partially compensate for any small deviations in the conveying speed at the inlet 452 and outlet 454. For this purpose, as in the first exemplary embodiment, a sensor system 470 is provided with which the current filling level of the buffer memory 450 can be recorded and signals representing the filling level can be generated, which are processed in the control unit 490 in order to variably set the conveying speed of the auxiliary feed device 430 so that at while the forming machine is running unchanged, the filling level of the buffer store 450 always remains between a minimum permissible filling level and a maximum permissible filling level. The sensor principle used and the control routine can correspond to those that have been described in connection with the first example, which is why it is not repeated.

A further exemplary embodiment of a wire processing system 600 is described with reference to FIG. 3. The forming machine 200 can be constructed similarly or identically to the forming machine 200 of the first exemplary embodiment and, in the example, is designed as a spring coiling machine with a feed device 210, forming tools 222 and a control unit 290 for controlling the forming machine. For a further description of the forming machine, reference is made to the first exemplary embodiment. In addition to the forming machine 200, the wire processing system 600 comprises an upstream device 700 in the material flow device for feeding the elongated wire-shaped workpiece material 110 to the forming machine. This device 700, which is also referred to as a feed device 700, has some differences from the feed devices of the previous exemplary embodiments. Some elements that have similar or identical construction and / or properties as in the first exemplary embodiment are denoted by the same reference symbols, increased by 400.

As in the first exemplary embodiment, the workpiece supply is in the form of a coil 112 on a rotatably mounted reel 710. In contrast to the first exemplary embodiment, this is not driven, which is referred to here as a passive reel. The axis of rotation of the reel is horizontal. The wire 110 is drawn off from this passive reel with the aid of the auxiliary feed device 730 driven by the auxiliary drive 735, the wire being guided between the reel and the auxiliary feed device 730 via a deflection device 725, which e.g. can be designed as a roller or cylinder rotatably mounted about a horizontal axis. The deflection device is also rotatably mounted and has no drive of its own. In contrast to the voltage equalization device of FIG. 1, the axis of rotation is arranged in a spatially fixed manner. The embodiment from FIG. 3 thus has no voltage compensation device.

The downstream buffer store 750 is arranged in the direction of material flow behind the auxiliary intake device 730. This is oriented vertically and receives a flat vertical U-shaped wire loop 115 of variable length. The dimensions of the storage box in the longitudinal and transverse directions can correspond to those of the first or second exemplary embodiment. The inlet 752 and the outlet 754 of the buffer store are at the same level. In the direction of material flow behind the outlet 754, a passive deflection roller is attached above the buffer store, so that the fed wire can enter the feed device 210 horizontally.

The degree of filling of the buffer store 750 is detected by means of the sensor system 770 which, like the sensor system of the other exemplary embodiments, has four sensors S1 to S4 arranged in series with corresponding functionality.

During operation, the wire 110 is drawn upwards from the spool or the material supply by the auxiliary draw-in device 730 and sets the reel in rotation. In some embodiments, the reel is freely rotatable. In the illustrated embodiment, a braking device is provided in order to stop the rotary movement of the reel when the wire is drawn off brake. The braking device can act, for example, on the circumference of an end disk of the reel or on the central shaft of the reel. It is possible for the braking device to be activated in a controlled manner, for example via signals from the control device 790, as soon as the auxiliary draw-in device 730 stops the draw-in movement. It is also possible that the moment of inertia of the reel or the reel is increased by means of a permanent frictional contact and then, due to the friction when the auxiliary feed is stopped, it does not rotate or only rotates slightly at a rapidly decreasing rotational speed. This variant can also be referred to as a take-off reel or a braked reel.

This configuration can be advantageous compared to the embodiment of FIG. 1 because it has a simple structure since both the reel drive and the tension compensation device are omitted. In addition, the solution is very space-saving due to the vertical orientation of the workpiece loop in the buffer store.

Components of this feed device 700 can be provided both in a vertical and in a horizontal orientation and can be combined with one another in a suitable manner. The same sequence of units can thus also be provided in a reel with a vertical axis of rotation and / or in an embodiment with a horizontally oriented buffer store.

Claims

1. A method for feeding an elongated workpiece (110) to a forming machine (200) which has a feed device (210) which can be operated with a varying feed speed for drawing in the fed workpiece and for conveying the workpiece to a tool area (220) of the forming machine, wherein: a workpiece supply (112, 412) is provided in the form of a coil,

Workpiece sections are fed from the workpiece supply to an auxiliary feed device (330, 430, 730),

the auxiliary feed device (330, 430, 730) is driven by means of an auxiliary drive (335, 435, 735) and conveys the workpiece at a predeterminable conveying speed into a downstream buffer store (350, 450, 750),

the workpiece (110) in the buffer store (350, 450, 750) between an inlet (352, 452, 752) and an outlet (354, 454, 754) of the buffer store

Workpiece loop (115) of variable length forms, and

the workpiece is guided from the outlet (354, 454, 754) of the buffer store (350, 450, 750) to the feed device (210) of the forming machine, wherein

a filling level of the buffer memory (350, 450, 750) is detected by means of a sensor system (370, 470, 770), and

the conveying speed of the auxiliary intake device (330, 430, 730) is controlled as a function of sensor signals from the sensor system.

2. The method according to claim 1, characterized in that controllable components of the device, in particular the auxiliary intake device (330, 430, 730), are controlled in such a way that the workpiece (110) on an entry side of the intake device (210) with a tensile force that is essentially constant over time is loaded or is essentially free of tensile force.

3. The method according to any one of the preceding claims, characterized in that the workpiece supply (112) is provided in the form of a coil on a reel (310) which is driven in rotation by means of a reel drive (315), workpiece sections from the workpiece supply via a tension compensation device (320) to the auxiliary feed device (330), wherein the tension compensation device (320) preferably has at least one movably mounted deflection device (325) which is pretensioned in a clamping configuration to maintain workpiece tension, with a speed of the reel (310) preferably in Dependence on a position of Deflection device (325) of the voltage compensation device (320) is variably controlled.

4. The method according to any one of claims 1 or 2, characterized in that the workpiece supply (112) is provided in the form of a coil on a non-driven, passive reel (710), workpiece portions from the workpiece supply directly or via a deflection device (725) to the auxiliary draw-in device (730), with the passive reel (710) preferably being assigned a passive or actively controllable braking device which brakes the reel rotation when braking or stopping the draw-in movement of the auxiliary draw-in device (730).

5. The method according to any one of claims 1 or 2, characterized in that the workpiece supply (412) is provided in the form of a coil in a preferably non-rotatable container (410).

6. The method according to any one of the preceding claims, characterized in that the workpiece (110) between the inlet (352, 452, 752) and the outlet (354, 454, 754) of the buffer store (350, 450, 750) has a free workpiece loop forms in such a way that there is no mechanical deflection between the inlet and the outlet, a U-shaped free workpiece loop (115) preferably being formed.

7. The method according to any one of the preceding claims, characterized in that the workpiece in the buffer store (359) forms a horizontally lying workpiece loop.

8. The method according to any one of the preceding claims, characterized in that the workpiece (110) is guided from the outlet (354) of the buffer store (350) directly in a straight line to the feed device (210) of the forming machine.

9. The method according to any one of the preceding claims, characterized in that workpiece sections of the workpiece in an area between the workpiece supply (412) and the auxiliary feed device (430) and / or in an area between the outlet (454)) of the buffer store (450) and the intake device (210) can be guided by means of a guide device (420, 460) along a guide path which is curved at least in sections, the guide device (420, 460) preferably having a pipe or a hose for guiding the workpiece sections through.

10. The method according to any one of the preceding claims, characterized in that a multi-stage or continuously operating variable regulation of the conveying speed (v _H (t)) of the auxiliary intake device (330, 430) takes place.

11. Device (300, 500, 700) for feeding an elongated workpiece (110) to a forming machine (200), which has a feeding device (210) that can be operated with a varying feeding speed for feeding 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, 412) in the form of a coil;

an auxiliary intake device (330, 430, 730) connected downstream of the receiving device, which can be driven by means of an auxiliary drive (335, 435, 735) and is configured to convey the workpiece at a predefinable conveying speed to a downstream buffer store (350, 450, 750);

a buffer store (350, 450, 750) connected downstream of the auxiliary intake device with an inlet (352, 452, 752) and an outlet (354, 454, 754) for the workpiece, the buffer store being designed such that the workpiece is in the buffer store between can form a workpiece loop (115) of variable length at the inlet and outlet;

a sensor system (370, 470, 770) for detecting a filling level of the buffer memory (350, 450, 750) and for generating sensor signals representing the filling level; wherein a control device (390, 490, 790) of the device (300, 500, 700) is configured such that the conveying speed of the auxiliary intake device (330, 430, 730) can be controlled as a function of sensor signals from the sensor system (370, 470, 770) .

12. The device according to claim 11, characterized in that the receiving device has a reel (310) which can be driven to rotate by means of a reel drive (315), the reel being followed by a tension compensation device (320 with at least one movably mounted deflection device (325), which is pretensioned in a clamping configuration to maintain workpiece tension, the tension compensation device (320) preferably being designed as a sensor system of a control circuit for regulating the reel speed.

13. The device according to claim 11, characterized in that the receiving device has a non-driven, passive reel (710) and workpiece sections of the The stock of workpieces can be guided directly or via a deflection device (725) to the auxiliary draw-in device (730), the passive reel (710) preferably being assigned a passive or actively controllable braking device for braking the reel rotation when braking or stopping the draw-in movement of the auxiliary draw-in device (730).

Device according to claim 11, characterized in that the receiving device has a preferably non-rotatable container (410) for receiving the workpiece supply (412).

15. Device according to one of claims 11 to 14, characterized in that in an area between the workpiece supply (412) and the auxiliary intake device (430) and / or in an area between the outlet (454) of the buffer store (450) and the intake device (210) a guide device (420, 460) for guiding workpiece sections is arranged along a guide path that is curved at least in sections, the guide device (420, 460) preferably having a pipe or a hose for guiding the workpiece sections through.

16. Device according to one of claims 11 to 15, characterized in that the buffer store (350, 450, 750) is designed to receive a substantially U-shaped free workpiece loop (115), wherein the buffer store (350, 450, 750 ) has a flat storage box (355) which has a cuboid interior in which the workpiece can form a substantially U-shaped loop between the inlet (352, 452, 752) and the outlet (354, 454, 754), wherein legs of the U-shape that are essentially parallel to one another run parallel to the narrow sides of the storage box (355) and are connected via an arcuate section on the side facing away from the inlet (352, 452, 752) and outlet (354, 454, 754), wherein preferably a length of the storage box (355) measured parallel to the narrow sides is a multiple, in particular at least ten times, the width of the storage box measured between the narrow sides.

17. Device according to one of claims 11 to 16, characterized in that the buffer store (350) is designed as a horizontal store, so that the inlet (352) and the outlet (354) are at the same level.

18. Device according to one of claims 11 to 17, characterized in that the sensor system (370, 470) is configured as a contactless sensor system.

19. Device according to one of claims 11 to 18, characterized in that the sensor system (370, 470) has three or more sensors (S1-S4) arranged at a distance from one another in the longitudinal direction of the buffer store (350, 450).

20. Wire processing system with a wire processing forming machine (200), which has a feed device (210) that can be operated with varying intake speed for drawing in the fed wire and for conveying the wire to a tool area (220) of the forming machine, the wire processing system having a device (300, 500) for feeding a wire (110) to the forming machine (200) according to one of claims 11 to 19.