Patent Application
20230372991
This disclosure concerns a bending machine for producing complex bent parts from straight wire rods and a wire-processing system comprising such a bending machine.
Bending machines typically comprise a computer-numerical control unit, a transport system for transporting successive wire rods along a transport path, and a plurality of workstations arranged along the transport path, wherein at least two of the workstations are configured as bending stations. The transport system has a plurality of workpiece-receiving devices each for receiving a single wire rod. It is therefore a computer-numerically controlled, multistation bending machine which can process wire rods. Such bending machines are normally used to produce large quantities of complex bent parts in a short time. A complex bent part is a bent part which has more than one bend, wherein the bends may partly also lie in different planes to give a three-dimensionally bent part.
The demand for complex bent parts exists amongst others in the sector of electrical mobility. There, increasingly vehicles with fully or partly electric drive are offered. The vehicles usually have powerful energy storage systems with multiple battery modules. The electrical energy must be transported between the individual battery modules. For this, insulated and bent copper or aluminum rails are used, also known as “busbars.” Furthermore, increasingly, the wiring looms running in the vehicle longitudinal direction between front and rear are being replaced by busbars. Since the installation space available for routing busbars is sometimes relatively constricted and geometrically complex, in many instances busbars are required which have bends at one or more locations.
Also, to produce coil elements for construction of stators for electric motors, known as “hairpins,” often wire materials in the form of insulated and bent copper or aluminum wires with substantially rectangular or square cross-section are used.
EP 3 663 015 A1 describes a machine that produces wire elements with two legs running substantially in a plane, with their apex lying outside the plane of the legs. The geometry is typical, e.g., for hairpins. The machine has a supply device for substantially rectilinear wire blanks with a predefined length; a first bending device configured to perform a first bending process on the wire blanks supplied by the supply device to produce flat wire elements with two legs and an apex; a plurality of second bending devices which each comprise a different embossing element, wherein the second bending devices are all configured to bend the apex of the flat wire elements out of the plane of the legs. Furthermore, a first transport device is provided which is configured to transfer the wire elements from the first bending device to one of the plurality of second bending devices. The control device of the machine is operationally coupled to the supply device, the first bending device, the second bending devices and the first transport device for controlling these, and in particular is configured to actuate the first transport device on the basis of process parameters for transferring wire elements to a selected one of the second bending devices. That concept allows amongst others a high productivity and high flexibility in the production of bent parts with different bend geometry.
It could nonetheless be helpful to provide a bending machine of the above type that offers a high productivity and great flexibility in the production of bent parts with different bend geometry, and is distinguished by compact installation size and correspondingly little space requirement.
We provide a bending machine that produces complex bent parts from straight wire rods including a computer-numerical control unit; a transport system that transports successive wire rods along a transport path, wherein the transport system has a plurality of workpiece-receiving devices each for receiving a single wire rod; a plurality of workstations arranged along the transport path, wherein at least two of the workstations are configured as bending stations, wherein at least one bending station includes a bending unit configured as a rotary draw bending unit.
We also provide a wire-processing system that produces complex bent parts from wire including a rod make-up machine that produces straight wire rods of pre-definable length from wire material; a bending machine downstream of the rod make-up machine that produces bent parts with complex bends from the straight wire rods, wherein the bending machine is a bending machine that produces complex bent parts from straight wire rods including a computer-numerical control unit; a transport system that transports successive wire rods along a transport path, wherein the transport system has a plurality of workpiece-receiving devices each for receiving a single wire rod; a plurality of workstations arranged along the transport path, wherein at least two of the workstations are configured as bending stations, wherein at least one bending station includes a bending unit configured as a rotary draw bending unit.
Further advantages and aspects arise from the appended claims and the description of examples which are explained below with reference to figures.
Our generic bending machine comprises at least one bending station with a bending unit configured as a rotary draw bending unit. Such a bending unit, when fitted with a rotary draw bending tool, is able to shape the wire rod in a rotary draw bending process. A bending unit configured as a rotary draw bending unit is also described in this application as a bending unit of a first type.
A rotary draw bending unit has a bending head on which, in configured state, i.e., with tool components for rotary draw bending attached, a bending form is arranged. In a rotary draw bending operation, a portion of the wire rod to be shaped is brought into a starting position in the engagement region of the bending head. Then a clamping element of a clamping device is brought into contact with a free wire portion to clamp this wire portion against a peripheral portion of the bending form and firmly clamp it to the bending form. The wire portion is thereby fixed between the clamping element of the clamping device and the bending form. Furthermore, a counterhold device is brought into engagement with a supply-side portion of the wire rod to stabilize the orientation of the longitudinal axis of the supply-side portion during a bending operation.
Then in a bending operation (rotary draw bending operation), by synchronous rotation of the bending form and clamping device about the bending head axis, a bend is created between the supply-side portion, stabilized against transverse forces by the counterhold device, and the clamped wire portion. The synchronous rotation of the bending form and clamping device about the bending head axis also “pulls” the workpiece around the bending form or a peripheral portion thereof. The outer contour of the bending form may thus stabilize the inner contour of the bend and precisely predefine its radius. The rear straight leg of the workpiece, i.e., the supply-side portion, is supported by the counterhold device which acts a counter-bearing to absorb the transverse forces resulting from the bending, and thereby remains ideally oriented parallel to a passage direction. The passage direction corresponds to the direction in which the wire rod is supplied in the direction of the bending form.
Ideally, a planar bend is produced in which the legs before and after the bend, formed by the end portion of changed orientation and the supply-side portion of unchanged orientation, lie in a common plane. The relative orientation of the end portion relative to the supply-side portion is usually described as the bend angle. By rotary draw bending, the desired bend angle and bend radius can be generated with high precision.
A preferred example of a rotary draw bending unit (bending unit of the first type) has a bending head which is rotatable about a bending head axis by a bending drive, and movable parallel to the bending head axis by a feed drive. In the configured state, the bending head carries at least one bending tool with a bending form, which is rotatable about the bending head axis by the bending drive. The rotational axis driven by the bending drive is designated for simplicity as the Y axis. The linear axis driven by the feed drive is designated for the sake of simplicity as the Z axis.
The Z axis is arranged transversely to the passage direction of the wire rod through the bending station and advances the bending head in the direction of or away from the wire rod. By the rotatable bending tool, which cooperates with one or more further tool parts of the bending head, a planar bend can be created on the wire rod in one bending operation.
The preferred rotary draw bending tool (bending unit of the first type) also has, in addition to the Y axis and Z axis, a machine axis (e.g., W axis) for actuation of a clamping device which is configured for clamping a portion of the wire rod against a peripheral portion of the bending form mounted on the bending head.
A rotary draw bending unit thus comprises at least three (regulated) machine axes.
In some examples, a rotary draw bending unit also comprises a linear axis for displacement of the bending head parallel to a passage direction of the wire rod (X axis, longitudinal adjustment). Thus, amongst others, in rotary draw bending, compensation movements can be generated in the wire longitudinal direction to prevent the wire being stretched by undesirable traction loading.
In some configurations, the rotary draw bending unit also has a linear axis for displacement of the bending head perpendicularly to the passage direction. This optional linear axis is here designated the B axis and allows a transverse adjustment of the bending head. Thus, in a simple fashion, bends can be generated in both directions. Also, the B axis allows use of multistage bending forms with different bend radii.
In some configurations, a rotary draw bending unit also has a rotational axis for rotation of a clamping device of the bending unit about the passage axis. This optional rotational axis is here also designated the A axis and allows creation of a twist or twisted portion in the wire rod during the rotary draw bending.
A rotary draw bending unit may thus have two or three rotational axes and two or three linear axes. More machine axes are possible but often not required.
In some configurations, at least one bending station has a base bending unit with a bending head which is rotatable about a bending head axis (Y axis) by a bending drive, and movable parallel to the bending head axis (Z axis) by a feed drive, wherein no machine axis is provided for actuation of a clamping device. Such base bending units may economically be provided with robust structure and, when equipped with a bending tool, allow free-form bending in which, within constructional limits, different bend geometries can be achieved without conversion of the bending station, purely by a change of actuation. Thus, great flexibility is achieved with respect to possible bend geometries. A base bending unit in this application is occasionally also called a bending unit of the second type.
It is particularly favorable if the bending units are oriented relative to one another such that the bending head axes of at least one rotary draw bending unit and at least one base bending unit are oriented transversely, in particular orthogonally to one another. In this example, bending operations which run in mutually different planes can be divided over the different bending stations with bending units of the first type and second type, without the workpiece and/or a bending unit having to be rotated over great rotational angles about the passage axis. Any rotation about the passage axis can be restricted to small angles of, for example, less than 45°. An orthogonal arrangement may be particularly advantageous, e.g., for wires with square or non-square, rectangular cross-section.
Bending stations may also be provided with bending units of different design. Preferably, the bending machine however comprises exclusively rotary draw bending units and base bending units. Thus, no great range of variants is required, which limits costs.
In one example, bending stations directly following one another along the transport path are at least partly arranged at different intervals from one another. In this way, the installation space available can be utilized better than in constant intervals.
In a bending machine according to one example, the transport system comprises a plurality of transport units which each have a workpiece-receiving device for receiving a single wire rod. Preferably, each transport unit is movable along the transport path by the control unit according to an individual movement profile.
The transport units, controllable with different movement profiles, and thereby necessary supplementary measures, may be provided independently of the type and design of bending stations or bending units at bending stations (also at other generic bending machines) and bring advantages so that this aspect is also regarded as an independent disclosure.
A bending machine according to this design leaves the conventional concept of fixed cycling as known, for example, in revolving machines. Instead, a transport system with variable cycling is provided. The term “variable cycling” means that not all transport units are in the same movement state at a given time, but they perform their individual transport tasks according to an individual movement profile, wherein the individual movement profiles of different transport units usually differ at least in certain movement phases. We found that a transport system with variable cycling, or with the possibility of asynchronous movement of the transport units, may make a decisive contribution to achieving high productivity, high flexibility with respect different geometries, and small surface area requirement of the bending machines.
In an individual movement profile, starting points, end points, momentary speeds and accelerations of the individual transport units may be variably predefined by the control unit. The movement profiles may thus differ, for example, for different path portions. The variable cycling allows, inter alia, many degrees of freedom not conventionally present, with respect to placing of workstations along the transport path. For example, the intervals between successive workstations may be different. This favors the reduced space requirement. The degrees of freedom with respect to the arrangement may be utilized to place the individual workstations matched to one another, for example, with respect to the time required for the corresponding work operations. Individual transport units (one or more) may move while others are stationary at the same time, e.g., during a bending operation. Longer bending times (duration of a bending operation at a bending station) may be compensated at least partially with shorter transport times.
Preferably, the transport system comprises a transport path with at least one linear motor unit and guide rails for guiding the movement of the transport units, wherein the transport units are movable magnetically along the guide rails via the linear motor unit under control by the control unit. The transport path may be rectilinear and/or be formed by a single linear motor unit. Preferably however, several successive linear motor units and associated guide rails are provided. The computer-numerical control unit with operating software installed thereon allows an independent actuation of the individual transport units with individual movement profiles. When this concept is used, a transport unit does not require its own travelling drive for progress along the transport path. Instead, the transport unit may comprise the passive secondary part of a linear motor with one or more permanent magnets. The omission of dedicated drives may contribute to designing the individual transport units relatively lightly or with little mass inertia so that good acceleration and high speed are possible.
In other examples, it may be provided to integrate a dedicated drive in the transport unit, for example, an electric motor, and create the energy supply via the guide rails or a separate rail.
Alternatively, the transport path is a closed transport path. Thus, even when many bending stations are provided, compact installation dimensions can be maintained. With a closed transport path, returning the transport units from an end position of their movement back to the starting position is particularly simple. The transport path may be circular or consist of a combination of straight portions and curved portions. In one example, the transport path is rectangular with two long sides and two short sides, and with 90° curves at the corners.
Conventional fixed cycling as implemented, for example, in revolving machines, can in principle also be used in conjunction with bending stations for rotary draw bending. The transport system could thus also comprise a revolving table on which several workpiece receivers are arranged, e.g., with fixed pitch.
Aspects of possible concepts for the workpiece receivers for transport and machining are explained below.
In many examples, components of the workpiece-receiving device in contact with the workpiece are mounted rotatably about the receiving axis of the workpiece-receiving device. The receiving axis determines the orientation of the received wire rods, the longitudinal center axis of which in the region of the workpiece-receiving devices should run as coaxially as possible to the receiving axis. Such a rotatability may increase the flexibility of the process guidance on bending, in particular rotary draw bending.
In many examples, the workpiece-receiving device of a transport unit comprises a clamping device with at least one movably mounted clamping element and an actuating element coupled therewith, wherein by actuation of the actuating element, the clamping device can be switched between a locked configuration and an unlocked configuration. The unlocked configuration allows insertion of the wire rod or removal of the finished bent part from the clamping device without mechanically loading the workpiece. In the locked configuration, the clamping forces exerted by the clamping device on the wire piece are sufficient to prevent the workpiece from slipping in the clamping device during transport.
Preferably, the movable holding element is elastically preloaded into the locked configuration by a spring arrangement. Thus, an elastic clamping is achieved which protects the workpiece. The clamping force is determined by the spring force of the spring arrangement which may comprise a single spring or several springs. For insertion of the wire piece in the clamping device, the holding element is retracted against the spring force; the locked configuration is assumed automatically on release of the holding element. The elastic clamping generally protects the workpiece. It is particularly advantageous when processing insulated wire rods as used, for example, for hairpins or busbars since this type of clamping does not load the insulation layer unnecessarily heavily. Since the clamping force is provided by the spring arrangement in the locked configuration, the clamping device requires no external energy which would have to be provided, for example, electrically or pneumatically.
The concept with spring-loaded holding element is a robust, fully mechanical solution with low own weight, so to this extent transport units with lower mass inertia are possible.
Preferably, a transport unit therefore has no actuator which can be operated with external energy, for example, a pneumatically or electrically actuatable gripper or similar.
For correct operation of the bending of wire rods, the bending machine must be loaded. This can take place manually. Preferably however, one of the workstations is a loading station for automatic or automatable transfer of wire rods from an upstream unit for providing straight wire rods to the bending machine.
The loading station preferably comprises an actuating device, controllable via the control unit, to actuate the movable clamping element of a transport unit. The loading station may thus switch the transport unit between the locked configuration and the unlocked configuration or vice versa, so no operator intervention is required for these steps.
Preferably, one of the workstations is an unloading station for transferring bent parts from the bending machine to a downstream unit, wherein the unloading station preferably comprises an actuating device, controllable via the control unit, to actuate the movable clamping element of a transport unit. The downstream unit may, e.g., be a collection container or magazine for receiving finished bent parts. The downstream unit may also ensure further transport of the bent parts to downstream processing devices.
Preferred examples comprise features relating to the cooperation between the bending station and transport unit which conveys the wire piece to be bent into a machining position at the bending station and later out of this again.
In some examples, a bending station is configured such that the workpiece-receiving device of a transport unit, moved into the machining position, acts as a functional component of a workpiece-receiving device for receiving a wire rod for a bending operation. Thus, no handover of the wire rod between the transport unit and bending station is required so that faults caused by handover are systematically avoided and simpler construction of the bending station is possible.
Preferably, a bending station has a clamping device configured to grip on the workpiece-receiving device of a transport unit, moved into the machining position such that machining forces occurring on a bending operation are absorbed by the clamping device of the bending station. In this example, the bending station has no parts in contact with the workpiece for fixing the wire rod. Rather, the clamping device of the workpiece-receiving device serves as a functional part of the workpiece-holding device at the bending station. However, no or only slight machining forces are transmitted to the transport unit. Thus, the transport unit needs no specific complex construction with respect to force loading, and the region in which the transport units cooperate with the guide system experiences no potentially critical mechanical load during the bending operation performed on the wire piece.
With this design, a bending station needs no dedicated workpiece-receiving device to receive a wire rod for a bending operation.
Preferably, the clamping device of the bending station is configured such that a clamping force exerted on the wire rod by the clamping device of the workpiece-receiving device is reinforced by the clamping device of the bending station. This may ensure that even at high machining forces, the wire rod cannot slip out of the workpiece-receiving device of the transport unit during the bending operation.
Preferred transport units are thus used in two working states of their workpiece-receiving device. In one state, the workpiece is clamped merely by spring loading, wherein the clamping force need only be so great as to reliably prevent the wire rod from slipping out during transport. In the second state, higher clamping forces occur which are sufficient to fix the wire rod reliably in the desired position during the bending operation.
In transport systems in which each transport unit is movable along the transport path by the control unit according to an individual movement profile, a particularly workpiece-protective transport can be achieved in particular for relatively sensitive workpieces such as, e.g., relatively thin wire pieces. In some configurations, it is provided that the control unit is configured such that the individual movement profile of a transport unit, during movement along the transport path in it least one compensation time interval, includes a compensation movement of the transport unit for avoiding and/or damping vibrations and/or reducing centrifugal force.
During the compensation time interval, for example, the transport unit can thus be moved so that no vibration not previously present is generated in the transported wire rod. Alternatively or additionally, the movement profile may be configured such that vibration energy is extracted or diverted from an already excited vibration so that vibration damping can be achieved. A compensation movement to reduce centrifugal force may, e.g., entail the travel speed of a transport unit being reduced on transition from a rectilinear portion to a curved portion of the transport path, and/or increased on transition from a curved portion to a rectilinear portion of the transport path. Thus, curved portions can generally be traversed more slowly than straight portions. This may avoid the creation of undesired bend elements on a transported wire rod because of centrifugal forces, which elements would leave an undesired residual deformation on the wire rod if there were no compensation movement. This helps ensure that the geometry of the finished bent part corresponds to the nominal geometry within tight tolerances.
Further contributions to achieving maximum geometric precision of the finished bent parts are made in some configurations in which the workstations include at least one measuring station with a measuring system for measuring the geometry of the bent part after machining by the bending station, wherein the control unit is configured to process measurement signals from the measuring system and control (subsequent) bending operations at the bending station, and/or bending operations at a downstream bending station, depending on the measurement signals. Thus, a regulated bending process can be applied which ideally allows production substantially only to produce good parts, or few or no rejects.
The measuring station may be physically downstream of the bending station and measure the bending result of the physically upstream bending station. It is also possible to integrate part of the measuring system of the measuring station, e.g., a camera, in the bending station to measure the bending result. To this extent, here too, the bending station lies functionally upstream of the measuring station. The workstation could then be called a combined bending and measuring station.
If the measurement signal is used to control the upstream bending operation, in some examples the machining parameters may be modified at this bending station for machining the next supplied wire rods, to not reproduce geometry errors detected on measurement. In this configuration, the measuring station is used as an after-measuring station. Alternatively or additionally, it is also possible to use the measuring station as a pre-measuring station in which, on significant deviations of the geometry of the bent part from the nominal geometry following the preceding bending step, the measurement signals are used to structure the following bending operations (one or more) differently from the former parameter sets so that a detected geometry error in the bent part is at least partially corrected by subsequent bending operations. In this configuration, the measuring station works as a pre-measuring station in which the measurement signals are used to modify the following bending operations (one or more) with a view to reducing geometry errors.
The measurement may be performed such that the measurement object (fully or partially bent wire rod) is at rest during measurement. Thus, maximum measurement precision can be achieved. By a moving transport unit, the measurement object can also be moved during measurement, whereby different measurement strategies can be implemented.
Thanks to integrated testing and regulation of the geometry features (e.g., leg position or contact surface properties for hairpins of busbars), thus, quality control may be integrated.
We also provide a wire-processing system for producing bent parts with complex bends from wire. The wire-processing system comprises a rod make-up machine for producing straight wire rods of pre-definable length from wire material, and a bending machine downstream of the rod make-up machine for producing complex bent parts from the straight wire rods. The bending machine is designed according to our general concepts or one of their examples.
The computer-numerically controlled, multiaxis wire-processing system 100 has a plurality of controllable machine axes, a drive system with multiple, usually electric drives for driving the machine axes, and a computer-numerical control device 190 for coordinated control of work movements of the machine axes in a production process, according to a computer-readable control program specific to the production process. Each machine axis has at least one drive, e.g., an electric motor. The drive drives a movably mounted component of the machine axis. Depending on the nature of the movement of the component to be driven (rectilinear movement or rotary movement), one distinguishes between translational machine axes, here also referred to briefly as linear axes, and rotational machine axes, here also referred to briefly as rotational axes. A linear axis may drive, e.g., a linearly movable slide. A rotational axis may drive, e.g., a turntable.
In this example, the wire-processing system has a rectangular machine coordinate system MK characterized by lower-case letters x, y, and z, with a vertical z axis and horizontal x and y axes. In the example shown, the x axis runs parallel to the passage axis of the wire. The three regulated and driven machine axes, which are designated partly in upper-case letters (for example, A axis) at arrows, should be differentiated from the coordinate axes x, y and z. The arrows or double arrows represent the work movements which can be generated via the respective machine axes or their drives. The drives are where applicable characterized by the corresponding capital letters of the axis and a suffix “-A” so that, e.g., the drive of the A axis is designated A-A.
The starting material D is present in the form of a wound material store (coil) which, in an example, is wound on a reel 105. In other examples, no reel is provided and the material store may also be present in and extracted from, e.g., a barrel-shaped holder.
The workpiece enters a rod make-up machine 200 with integrated stripping device 250. The rod make-up machine comprises, in this order along the passage axis of the workpiece, a straightening unit 220, a length measurement device 230, the stripper device 250 equipped with a milling device 240, a brushing device 260 downstream thereof, an infeed device 270 downstream thereof, and a cutting device 280 downstream of the infeed device. The rod makeup machine 200 has its own base 205 on which the components are installed.
The straightening device 220 has two successive straightening appliances with straightening rollers which successively machine the workpiece in two mutually perpendicular directions, thereby straightening it. The length measuring device 230 has a measuring wheel and an opposing running wheel, and allows precise measurement of the workpiece length conveyed to the following units. The advance movement is generated by the infeed device 270 which is arranged behind the stripping device 250 and pulls the workpiece through the upstream devices with an infeed profile predefinable via the controller 190, and conveys this to the downstream cutting device 280. The advance force in the infeed direction (x direction) results from friction between the infeed rolls of the infeed device and the wire. In other examples, a belt infeed or toothed rack infeed with reciprocally moved gripper is provided.
The cutting device 280 is directly downstream of the infeed device; no bending shaping of the flat material takes place inside the stripping unit 200 so that the cutting device separates straight wire rods DS of predefinable length from the partly stripped wire supplied.
These rods are transported individually and successively to a downstream bending machine 300 by a rod handover device 290. The longitudinal direction (direction of longitudinal center axis) of the wire rods DS here runs horizontally and parallel to the transport direction of the wire rods. This may be advantageous in particular for relatively thin wires since thereby undesired deformation on accelerated movements can be avoided. Also, this gives relatively short feed distances for the bending units, which can have a favorable effect on the processing speed.
The bending machine 300 has its own base 305, on the top side of which are arranged components of a transport system 310 for transporting successive wire rods along the transport path 312. The transport path runs in a horizontal plane (x-y plane). In
The transport path 312 is closed in the circumferential direction and has a substantially rectangular course with long sides running in the x direction and short sides running in the y direction. At the corner regions are 90° curved portions.
The transport system 310 comprises a plurality of individual transport units 320, for example, three, four, five, six, seven, eight, nine, ten or more transport units. The number of transport units should preferably correspond at least to the number of workstations so that the work steps can be carried out temporally in parallel with one another. Preferably, more transport units than workstations may be present. Each transport unit has a workpiece-receiving device 325 for receiving a single wire rod DS. In the region of the workpiece-receiving device, this runs coaxially to the receiving axis, horizontally and parallel to a passage direction which corresponds to the local transport direction on the transport path.
Each movement of a transport unit 320 may be carried out according to an individual movement profile which can be predefined by the control unit 190 on the basis of a computer program. The drive for the transport movement, i.e., for the movement along the transport path 312, is here actuated or supplied with power accordingly. The movement profile may, for example, be characterized by the distance covered on movement, the speed and/or the acceleration of movement, all as a function of time or other parameters.
The transport units 320 are advanced by linear direct drives. The transport path 312 is constructed with a plurality of successive linear motor units on which guide rails are provided for guiding the horizontal movement of the transport units. The primary parts of the linear motors supplied with current are situated in the transport path 312; inside the transport unit 320 are passive components (secondary parts) of the linear motors so that a transport unit 320 has no carrying drive for advance movement along the transport path.
With reference to
The unlocking unit 295 is part of a loading station 360 at which the straight wire rods DS are loaded into the transport system 310. For this, a transport unit 320 is moved into the loading position shown. The gripper 297 grips the actuating element and, with its assistance, pulls the upper clamping element 327 upward against the force of the spring arrangement 328 so that an unlocked configuration is reached and the wire rod DS can be inserted horizontally into the opened clamping device (workpiece-receiving device 325) without overcoming a resistance. When the desired position is reached, the clamping device is transferred into a locked configuration in which the actuating element 329 is released. The workpiece-holding device 327 holds the workpiece firmly with the force of the spring packet 328, wherein the holding forces act over a relatively long clamping length. Then the transport unit 320 with the clamped wire rod travels along the transport path to a first workstation of the bending machine. This is a bending station 320-1 which is the first bending station of the transport path.
In the exemplary configuration, the bending machine 300 has three bending stations arranged successively along the transport path 312, namely a first bending station 320-1, a second bending station 320-2 arranged behind this in the transport direction, and a third bending station 320-3 arranged behind this at a greater distance in the transport direction. Further bending stations may be arranged along the transport path so that, for example, four, five, six, seven or eight bending stations may be present. Bending stations may be arranged on each side of the transport path in different positions along the transport path. Corresponding fixing structures are prepared for this on the machine bed. During operation, the bending stations may work in parallel, i.e., simultaneously at least in phases, whereby high throughput rates are possible.
A bending unit is provided at each bending station, via which a bending operation can be performed on the wire rod. In the configuration shown, there are two different types of bending unit. At the first bending station 320-1 is a base bending unit 340-2 (bending unit of second type), with a horizontal bending head axis (see
Each bending station is also configured to carry out geometry measurements on the bent part produced there. For this,
The rotary draw bending unit 340-1 comprises a bending head 345 which can be rotated bidirectionally by a electric drive (bending drive Y-A) about the bending head axis 342. The associated rotary machine axis is the Y axis.
The bending head may be moved parallel to the bending head axis 342 by a feed drive Z-A (drive of translational Z axis). Thus, the bending head may also be advanced by movement radially to the passage direction of the wire rods for bending engagement, or be brought out of engagement with the wire rod.
In the configured state (equipped with rotary draw bending tool), the bending head 345 carries a bending form 346 which can be turned about the bending head axis 342 during rotary draw bending by the Y axis.
The unit comprising the bending head is carried by a slide running on horizontal guide rails arranged on the front side of a carrier mounted fixedly on the machine. The components carried by the slide can be moved parallel to the passage axis or transport direction (X axis) by a corresponding drive X-A.
The rotary draw bending unit 340-1 in this example has, in addition, a linear axis (B axis) which is driven via drive B-A and configured to displace the bending head 345 horizontally, perpendicularly to the passage direction or transport direction.
A further machine axis (W axis) is provided for actuation of a clamping device 347, via which a portion of the wire rod can be clamped against the periphery of the bending form. For the rotary draw bending, the wire is clamped between the bending form 346 and a clamping element of the clamping device 347. Then the bending form, clamping device and wire clamped in between rotate in synchrony.
In this example, the machine axis for actuating the clamping device 347 is a rotational axis (W axis) which is actuated independently of the Y axis and carries a component of the rotary draw bending tool. A relative twist of the W axis relative to the Y axis generates a movement of a clamping element, arranged on a pivot lever, until the wire is clamped. The W axis thus controls the wire clamping. Then the bending form, clamping device and wire clamped in between rotate in synchrony. Corresponding devices for eccentric clamping are shown, for example, in EP 2 208 549 A1.
In other examples, the clamping device may also be actuated by a linear axis which causes a linear displacement of a clamping element of the clamping device in the direction of the bending form 346 and back.
The bending station 320-1 does not have a dedicated workpiece-receiving device for receiving the wire piece to be bent. This is held during the bending operation by the workpiece-receiving device 325 of the transport unit 320 which is in the machining position (see
The workpiece-receiving device 325 of a transport unit 320, or the components thereof touching the workpiece, are mounted rotatably about a receiving axis. During a bending operation, this runs parallel to the passage direction. In this example, the holding elements of the workpiece-receiving device 325 of a transport unit 320 are mounted in a rotatable sleeve so that the workpiece-receiving device or its holding elements are rotatable about the longitudinal direction of the received wire rod or the passage direction. The bending unit 340-1 is configured such that, if necessary, it can generate a rotation of the components of the workpiece-holding device 325 in contact with the workpiece about the longitudinal axis of the wire. For this, an arcuate guide 354 is mounted in the carrying structure of the bending unit, via which the clamping device 350 as a whole can be rotated about a rotational axis which coincides with the passage axis of the wire rods. The corresponding rotational machine axis is the A axis.
Thus, it is possible, inter alia, to turn the holding elements about the axis of the held wire portion during the rotary draw bending so that on the wire piece, not only is a bend produced but at the same time a twisted portion, i.e., a residual deformation of the wire rod which occurs under torsion or twisting of the wire rod.
A rotary draw bending operation can now proceed such that a portion of the wire piece is clamped at the bending form 346 and the bend is produced by rotation of the bending form 345 such that the wire piece is pulled around the shaping contour of the bending form 346 without relative slipping. The wire portion is now under tensile stress between the bending head 345 and the clamping unit 350. To prevent the wire being stretched thereby, a compensation movement is generated by axial travel of the bending unit via the X axis. During the bending operation, the workpiece-receiving device 325 serves as a counterhold which ensures that the held wire portion retains its orientation during bending. This contributes to the high precision in the achievable bending angles.
Alternatively, the compensation movement may also be implemented by controlled movement of the transport unit in synchrony with the rotary draw bending movements of the bending head.
In some examples of the first type, there is also a torque support device 335, not illustrated in
If a twisted portion is to be produced by twisting, during at least one phase of rotation of the bending head 345 by the A axis, the clamping device 350 is also twisted so that a twisted portion TA is produced between the clamped portion at the bending head 345 and the clamped portion in the workpiece-receiving device 325. In examples with engagement of the torque support device, the torque support device also rotates during twisting via the A axis so that only the region close to the bending form is twisted.
A base bending unit 340-2, i.e., a bending unit of the second type, may be structurally simpler since a machine axis for actuation of a clamping device for wire clamping may be omitted.
Such bending units allow free-form bending in which, within structural limits, different bend geometries can be achieved without conversion of the bending station, purely by changing the actuation. This achieves high flexibility with respect to achievable bend geometries.
In the configuration of
In the example of
To ensure a consistently high quality of the finished bent parts, a measuring system is present at each bending station, via which geometric parameters of the bent wire rod are detected after completion of the bending operation and reported to the control unit 190 in the form of measurement signals or measurement data derived therefrom. This leads to a nominal-actual comparison of the geometries and then, in great deviations of the measured actual geometry from the nominal geometry stored in the control unit, in this stage bending parameters of the assigned bending station can be changed so that the bend geometry can be produced with smaller errors on the following wire piece. The measurement signal from the measuring station may also be used to change bending parameters at a following bending station such that any error occurring at a bending station can be partially or completely corrected at one or more following bending stations.
The transport system 310 with the individually controllable transport units 320 allows the desired physical distribution of the bending stations at varying intervals along the transport path. Thus, an overall compact structure with relatively little space requirement can be achieved. Productivity can also be increased by the transport system 310, as the total necessary transport times (secondary times) are shortened so that more time (primary time) remains for the bending operations. Thus, for example, after a relatively long bending operation, a bent part can be transported more quickly to the following bending station than in a relatively short bending operation. Also, some transport units can be advanced while other transport units remain stationary at their bending stations because the bending operation is not yet complete. Finally, a transport unit can be returned very quickly between the unloading station 380 and the loading station 360 so that there is no waiting time for the productive bending operations. In comparison with systems with fixed cycling such as, for example, a revolving transport system, variable cycling offers substantial practical and economic advantages.
The bending stations utilize the advantages of 3D bending without fixed-form tools, and allow flexible changing between different hairpin geometries and also between different geometries of bent parts provided for other applications. The bending machine is distinguished amongst others by a high output yield with little space requirement and economic investment costs.
| Number | Date | Country | Kind |
|---|---|---|---|
| 102020212558.9 | Oct 2020 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2021/076494 | 9/27/2021 | WO |
