CHAIN ​​BENDING MACHINE FOR MAKING A CHAIN

Description

FIELD OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to a chain bending machine for manufacturing chains with bent chain links.

[0002] Chains with chain links, which are bent from wire elements in a forming process, are nowadays manufactured on a large scale using special automated machine tools, which are usually called chain bending machines or chain manufacturing machines, occasionally simply chain machines.

[0003] Chain manufacturing typically involves two main processes: bending – usually called chain bending – and welding – usually called chain welding. In chain bending, chain links are formed from straight wire elements of suitable length, called pins or prongs, and connected to other chain links, which may also be bent from wire elements or manufactured in other ways, such as by forging. In the subsequent chain welding process, the bent, open chain links of a chain strand are welded together to form closed chain links, for example, using a suitable resistance butt welding process.

[0004] This application relates to chain link bending using a so-called bending mandrel. The starting workpiece for the actual bending operation to produce a chain link is a so-called pin. The pin is a rod-shaped piece of wire cut from a supply of wire. The length of the wire piece corresponds to the unfolded length of the desired chain link plus an additional welding allowance. The pin is pressed against a bending mandrel by a holding element and thus fixed in place. The bending mandrel is shaped around its circumference according to the desired inner shape of the link. After fixing, a corresponding bending tool engages each of the two wire ends extending beyond the bending mandrel and bends the respective end of the pin partially around the bending mandrel into the shape of a chain link.

[0005] German patent application DE 2 028 266 A describes a chain bending machine equipped with a bending mandrel. The chain bending machine comprises a bending unit for producing a bent chain link by bending a wire element around the bending mandrel in a bending plane. The bending unit has two sub-units arranged on opposite sides of a central plane of the bending unit perpendicular to the bending plane. The central plane passes through the bending mandrel. Each of the two sub-units has a bending lever that can be pivoted about a pivot axis perpendicular to the bending plane. The pivot axis is linearly displaceable. Each bending lever carries a bending tool, in the form of a rotatably mounted bending roller, at its free end facing the bending mandrel. This tool engages the wire element. During bending, the bending tools are moved along predefinable paths around the bending mandrel.The bending rollers are guided by guide rollers mounted in grooves. These grooves are provided in a body rigidly connected to the bending mandrel to form a replaceable block. This offers the advantage of allowing adjustment of the bending mandrel and the grooves outside the machine. Because guide rollers, rather than the bending rollers themselves, run in the grooves, the bending rollers can roll along the pin, which significantly reduces wear.

[0006] The published patent application DE 2 531 290 A1 describes a method for bending chain links from wire pins of a predetermined length, whereby the two free ends of the wire pin are each bent around a bending mandrel. A special feature is that a bending tool is placed in the area of ​​each free end of the pin, which is guided along a curved path during the bending process such that the contact point of the bending tool on the wire pin, at least in the final region of the bending process, runs approximately on an involute of a circle, the reference point of which corresponds to the center of curvature of the side of the bending mandrel facing the respective bending tool. This method has the advantage that the part of the bending tool resting on the pin practically does not shift during the bending process, so that no grinding or rolling marks are created on the pin surface.

[0007] Document CN 101 157 115 A, which forms the basis for the preamble of claim 1, discloses a chain bending machine with a bending mandrel and a bending unit for producing a bent chain link by bending a wire element around the bending mandrel in a bending plane. The bending unit has a main carriage that can be moved toward the bending mandrel or in the opposite direction using a hydraulic main cylinder. The carriage carries another hydraulic cylinder on each side of the main cylinder. Each of these additional hydraulic cylinders is coupled to a bending lever, at the free end of which a bending tool is arranged for engaging the wire element. The bending levers are mounted on the carriage plate so they can pivot about vertical pivot axes and are coupled to one another via a rotary joint. This design allows the bending tools to be moved around the bending mandrel along predetermined trajectories during bending.The hydraulic cylinders can be controlled via a programmable logic controller.

[0008] Chain bending machines should be able to cover the broadest possible range of chains, in particular a large wire diameter range, a wide variety of chain link geometries, different bending radii, different materials, etc. Setup times should be reduced as much as possible so that switching to new chain link geometries can be done with minimal mechanical changeover effort. TASK AND SOLUTION

[0009] Against this background, the invention aims to provide a chain bending machine of the type mentioned above, in which setup and adjustment times when changing between different chain link geometries are reduced compared to conventional solutions. In particular, increased operator safety and ease of use are also to be provided.

[0010] To solve this problem, the invention, according to one formulation, provides a chain bending machine with the features of claim 1. Advantageous embodiments are specified in the dependent claims. The wording of all claims is made clear by reference to the content of the description.

[0011] The chain bending machine is designed for producing chains with bent links. In its set-up state, it includes a bending mandrel. The bending mandrel is typically shaped according to the desired internal link geometry. It can be a split or a single-piece mandrel. A bending unit of the chain bending machine is designed to produce a bent chain link by bending a wire element around the bending mandrel. The bending takes place in a single plane, which means, among other things, that the neutral axis of the bent wire element lies in the same plane as all its sections. The bending unit has two sub-units. These sub-units are arranged on opposite sides of a central plane of the bending unit that is perpendicular to the bending plane. The bending unit can be more or less mirror-symmetrical to the central plane, so that the two sub-units also have a comparable structure.

[0012] Each of the sub-units comprises a bending tool carrier unit, which carries a bending tool on a component facing the bending mandrel. This bending tool is designed to engage the wire element. The bending tool is therefore the part of the bending unit that comes into contact with the wire material on the corresponding side of the bending mandrel. The bending tools are movably mounted on the supporting components of the respective bending tool carrier unit. This mobility is intended to ensure that the bending tool can optimally align itself with the workpiece at all times during the bending process, i.e., during the gradual deformation of the wire around the bending mandrel. The bending tools can be moved along predefined paths around the bending mandrel by means of the bending tool carrier unit during bending. The paths of the bending tools each extend only around a portion of the circumference of the bending mandrel.

[0013] A special feature of the chain bending machine is that it includes a freely programmable bending process control system, which is configured in such a way that different bending tool trajectories can be specified by entering input parameters into an input unit of the bending process control system via a control unit of the chain bending machine. This "free" programmability naturally only exists within the design limits, meaning that not all arbitrary trajectories can be specified. However, a wide variety of different trajectories can be generated within the design limits. This allows different trajectories of the bending tools to be set using programming alone, i.e., on the software side, thus providing a completely software-based trajectory control for the movements of the bending tools.

[0014] The input unit can be located on or near the chain bending machine. For example, a touchscreen connected to a PC and appropriate software can be used for displaying and entering data in plain text. Input from a remote location, possibly in another room or building, is also possible if required.

[0015] One advantage of this concept is that, with the exception of the wire-contacting components (especially the bending mandrel and, if applicable, bending tools, as well as any other geometry-dependent tools such as clamps, reversing jaws, treadle transport gripper jaws, etc.), no other components of the chain bending machine need to be replaced when switching between different chain link geometries. The "conversion" can therefore be largely carried out via programming, i.e., software. For example, compared to the solution described in DE 2 028 266 A, the replacement of the chain dimension-dependent die, which contains the guide groove for the guide rollers attached to the bending levers, is no longer necessary. Compared to conventional drive concepts with mechanical cam drives and a guide shaft, it is also no longer necessary to change cam discs or cam inserts for assembling multi-part cam discs.The chain bending machine can therefore be quickly and easily converted to different chain link dimensions within its working range, which is characterized, among other things, by the wire diameters it can process. During conversion, only the wire-contacting components need to be replaced with corresponding wire-contacting components of a different geometry. This results in significant reductions in assembly, setup, and adjustment times. Furthermore, operator safety and ease of use are improved compared to conventional solutions. The mechanical complexity can also be reduced compared to conventional solutions.

[0016] In some embodiments, the bending profile control system is configured such that geometric data of the chain link to be manufactured can be entered as input parameters at the input unit, and that the bending profile control system is configured to perform calculations specific to the chain link based on this geometric data. In some embodiments, the geometric data or input parameters describing the chain link geometry include the wire diameter, the inner pitch of the bent chain link (i.e., the clear distance between the inner chain loops in the longitudinal direction), the outer width of the chain link, and, if applicable, the residual cross-section to remain at the facing ends of wedge-shaped pins for the subsequent chain welding process.

[0017] To make input easier for the operator and to illustrate the meaning of the input parameters, the bending profile control system is preferably configured such that a field of an input mask can be generated on a display device of the operating unit, in which a bent chain link is schematically represented together with input fields for the associated geometry data.

[0018] The calculations specific to the chain link may include one or more of the following: calculation of the pin length; calculation of tool geometries; calculation of the path paths of the bending tools.

[0019] Based on the pin length specifications, the positions of the individual processing stations on the machine bed can be determined. Depending on the configuration of the chain bending machine, these can then be adjusted manually or automatically using suitable machine axes.

[0020] Based on the information on tool geometries, the operator can procure and install the appropriate tools.

[0021] Based on this, the bending paths or path curves of the bending tools can be calculated.

[0022] The bending tools are preferably bending rollers rotatably mounted on the respective bending tool carrier unit. In the event of relative movement between the circumference of the bending roller and the wire to be bent, the rollers roll along the wire without damaging the wire surface. The trajectory calculations are preferably performed under the boundary condition that the point of contact between the bending tool and the wire remains unchanged during the bending operation, so that no relative movement occurs between the bending tool and the wire and optimal force ratios are present at every stage of the bending operation. Particularly in these cases, other bending tools can be used as an alternative to bending rollers. For example, bending shoes can be provided instead of bending rollers to obtain a larger contact area instead of the line contact (given with bending rollers), thus reducing the local surface pressure.

[0023] There are various ways to design a bending tool carrier unit. In some variants according to the claimed invention, each bending tool carrier unit has a bending lever that can be pivoted about a pivot axis perpendicular to the bending plane. Each bending lever carries a bending tool at its free end facing the bending mandrel. Bending tool carrier units equipped with bending levers can have a very compact design and reliably transmit large forces. The pivoting bending lever is also linearly displaceable parallel to the bending plane, so that the bending tool can be guided along different trajectories parallel to the bending plane by a combination of linear displacement and pivoting movement.

[0024] Alternatively, in other variants according to the claimed invention, a bending tool carrier unit is provided for in that it has a cross table (also called an XY table), i.e., a two-axis system comprising two single-axis linear guide systems, which thereby enables the movement of a bending tool in two directions within the bending plane. This allows the bending tool to be guided along different trajectories parallel to the bending plane by means of a combination of two mutually orthogonal linear displacements.

[0025] According to another embodiment, a bending tool carrier unit comprises two coupled linear units pivotably mounted on the machine frame via pivot axes. The pivot axes are aligned parallel to each other but laterally offset such that one linear unit moves substantially parallel to a first direction, and the other linear unit moves substantially in a second direction orthogonal to the first. Each linear unit has extendable end pieces whose ends are coupled and support the bending tool in the coupling area. By controlled extension and retraction of the two linear units, it is possible to move the bending tool along virtually any path in the plane of motion (parallel to the bending plane).

[0026] In the variant according to the invention with bending levers, it is provided that each of the sub-units has a carriage which can be moved in a first direction parallel to the center plane and on which the bending lever of the sub-unit is rotatably mounted about the pivot axis, wherein a first drive group for moving the carriage has a first servo drive and a second drive group for moving the bending lever has a second servo drive, which is preferably carried by the carriage. With the aid of this design, almost any trajectory curves can be generated in the movement range of the bending tools via control signals to the servo drives. The linear back and forth movement of the carriage in the first direction controls a movement component lying in the first direction, the amount of which can be controlled as a function of time using the first servo drive.The second drive unit moves the bending lever and thus controls movement components of the bending tools that run perpendicular to the first direction or perpendicular to the center plane within the bending plane. The coupling of the movements generated by the servo drives of the subunits is electronically controlled via the control unit.

[0027] Preferably, the second servo drive is a moving drive that travels with the movement of the carriage. This allows the second servo drive to act on the associated bending lever or the bending tool attached to it over a short transmission distance. Alternatively, the second servo drive could be mounted in a stationary position and coupled to the bending lever via a flexible shaft or other flexible transmission device (e.g., a cardan shaft with length compensation).

[0028] In the variant according to the invention with cross table, a further slide would be provided instead of the bending lever, the linear movement of which is generated by the second drive group via the second servo drive.

[0029] Variants are particularly preferred in which the first drive group has a first cam coupled to the first servo drive and / or the second drive group has a second cam coupled to the second servo drive. The servo drives thus serve to rotate cams, creating servomechanical drive groups. This allows the movements of an output shaft of the servo drive to be mechanically transmitted unevenly (with a variable transmission function) to the respective driven component via a cam mechanism, the transmission function being determined by the cam profile or cam shape of the cam. The combination of servo drives with cams allows for a favorable design both with regard to the sometimes very high forces required during bending and with regard to the dynamics of the bending operation, i.e., the speed profiles of the tool movements.

[0030] In the variant with bending levers, the first drive group, comprising the first servo drive and the first cam, generates the linear reciprocating motion of the carriage, which carries the bending lever of the subunit and preferably also the components of the associated second drive group. In the variant with a cross table, the carriage carries another carriage instead of a bending lever.

[0031] Particularly advantageous are embodiments in which the control unit is configured such that the first cam and / or the second cam is driven in reverse between a first end position and a second end position. In contrast to conventional cam drives with a uniformly rotating drive motion, here the cam is rotated back and forth in opposite directions with a limited angle of rotation. The end positions define the limits of the transmission function realized by the cam. The mechanical complexity can be reduced compared to uniformly rotating drive motions.

[0032] Unlike conventional solutions where cam discs with different cam profiles and strokes were exchanged when switching between different chain link geometries, a reversing drive, or cam discs designed for reversing drives, eliminates the need to exchange cam discs when changing formats. The cam discs can be designed to be used unchanged for all operations within the working range of the chain bending machine and only need to be replaced in case of wear. The cam profile of the cam disc can thus be defined once for all chain link geometries within the working range. This eliminates the need for special design features that facilitate easy cam disc exchange, resulting in a particularly stable mechanical coupling between the servo drive and the cam disc, suitable for transmitting high forces.Torques can be designed appropriately.

[0033] In some embodiments with reversing cam drives, the first cam and / or the second cam has a cam profile with a linear slope. This means that, within the rotational angle range between the first and second end positions, the radial distance between the cam's center of rotation and the outer cam flank changes according to a linear function. It has been shown that this significantly reduces the computational effort required to control the connected servo drive compared to variants where complex nonlinear relationships between the rotational angle and the cam position are determined by the cam flank shape. Alternatively, slopes that can be described by an exponential function can be used. Variable slopes are also possible.

[0034] In variants with a reversing drive of the first cam disk, a positive-running scanning arrangement with two scanning elements connected to the slide can be assigned to the first cam disk. These scanning elements, implemented, for example, by scanning rollers, are arranged at a fixed distance from each other and engage opposite cam flank sections of the cam disk. In reversing mode and with limited rotation angles of less than 180° between the end positions, the cam profile can be designed such that, for all rotational positions within this operating range, the distance measured between the scanning elements on corresponding cam flank sections is always the same, regardless of the rotational position.As a result, the carriage is driven both in its forward and backward movement via the appropriately arranged scanning elements and a play-free conversion of the cam disc rotation into the linear carriage movement is possible.

[0035] In variants with a reversing drive of the second cam disk, a further development may provide that the second cam disk is assigned a positive-running scanning arrangement with two scanning elements connected to the bending lever (or another slide), wherein the scanning elements, for example realized by scanning rollers, are arranged at a fixed distance from each other and engage opposite cam flank sections of the cam disk.

[0036] Depending on the available installation space and other boundary conditions, a cam disc (first cam disc and / or second cam disc) can also be designed as a beaded cam. The beaded cam can consist of a single piece. It is also possible to design the inner and outer curves of the beaded cam as separate cam discs (so-called main and counter-curves). Grooved cams or a spring return mechanism can also be incorporated.

[0037] In preferred embodiments, a space-saving and power-transmitting arrangement between the servo drive and the driven component is achieved by coupling the first servo drive to the first cam disc via a first gearbox, with the cam disc being cantilevered on an output shaft of the gearbox. A cantilevered mounting here means that no bearing is provided for the cam disc on the side opposite the gearbox. The drive assembly can have a linear, extended structure, with the cantilevered cam disc located at one end. The cantilevered mounting allows the cam disc to be positioned in or near the plane containing the pivot axis of the bending lever and in which the force of the motion component transmitted via the slide movement is transferred.This results in a reduction of possible lateral forces on the components under load during bending, which also benefits the precision of the trajectory curve.

[0038] Alternatively or additionally, a corresponding arrangement of the components of the second drive group can be provided, so that the second servo drive is coupled to the second cam via a second gear, with the second cam being cantilevered on the output shaft of the gear. This makes it possible to arrange the cam relative to the bending lever so that they lie in a common plane. This ensures optimal power transmission for pivoting the bending lever.

[0039] To ensure consistent quality of the bent chain links and minimize rejects, a monitoring system for the operation of the chain bending machine and for detecting malfunctions is provided, according to a further development. This monitoring system preferably includes a drive monitoring subsystem capable of detecting and displaying overload situations caused by malfunctions. The drive monitoring subsystem can be designed to record the time-dependent motor torque curves of the individual machine drives of the machine axes and compare them with permissible value ranges, which may be represented as envelope curves. Operation can be automatically stopped if a situation defined as significant occurs, allowing for corrective action.

[0040] Further advantages and aspects of the invention emerge from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. Fig. 1 shows a schematic side view of a chain bending machine according to one embodiment; Fig. 2 shows a schematic isometric representation of components of a bending station of a chain bending machine according to one embodiment; Fig. 3 shows a schematic top view of a first sub-unit of the bending unit. Fig. 1 ; Fig. 4 shows a section of a field in the input mask, in which a curved chain link is schematically depicted. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0041] The schematic side view in Fig. 1 Figure 1 shows an exemplary embodiment of a chain bending machine 200 for producing chains with wire links bent into shape. The chain bending machine has a plurality of functional units mounted in a straight line on a machine frame 202. A Cartesian machine coordinate system MK is shown for orientation. In this example, its x-direction is horizontal and is also referred to here as the first direction. The y-direction, perpendicular to it and also horizontal in this example, is also referred to as the second direction. In this orientation, the z-direction points vertically.

[0042] A first feeding device 910, together with a downstream second feeding device 920, serves to feed the wire DR from a wire supply, which is typically in the form of a coil, i.e., a bundle of wire wound like a spool. The feeding devices 910 and 920 each have a pair of counter-rotating feeding rollers (roller feeding).

[0043] Between the infeed devices, a straightening unit 915 with two roller straightening devices connected in series is arranged, each having a number (in the example case five) of axially parallel straightening rollers, wherein the axes of rotation of the straightening rollers of the straightening devices connected in series are aligned orthogonally to each other.

[0044] A downstream length measuring device 925 has a measuring wheel and, opposite it, a running wheel which is pressed against the passing wire and thus ensures a slip-free contact between the measuring wheel and the wire.

[0045] An optional wire stamping device 930 is provided directly downstream of the length measuring device, which can be used to stamp a logo, lettering, number, or the like into the wire at predetermined locations as it is fed through. This optional component is not provided in other embodiments.

[0046] In the wire conveying direction behind it, a back bending device 935 is arranged, with which a back bend can be produced on the wire.

[0047] This is followed by a notching device 940 for creating notches on opposite sides of the wire without cutting it. A camera system with camera 945 is provided for monitoring the notch depth.

[0048] A downstream shearing station or cutting station 950 serves to cut off a piece of wire DS or a pin of a predeterminable length from the supplied wire at the notched point.

[0049] A downstream transport device 955 (also called tiller transport) serves to feed the tillers to the downstream bending station 210, the design and function of which are related, among other things, to the Fig. 2 and 3 will be described in more detail. Fig. 2 This shows a schematic isometric representation of some components of the bending station 210. Fig. 3 schematically shows a top view of a first sub-unit of a bending unit of the bending station.

[0050] All controllable components of the chain bending machine 200 are connected to the machine's control unit 190, which includes, among other things, the power supplies and position sensors for the drives, a central processing unit, and storage units. Using the control software active in the control unit, the movements of all machine axes can be variably controlled based on set parameters. A display and operating unit 195 connected to the control unit 190 serves as the interface to the machine operator.

[0051] Chain bending is automated in bending station 210 using a bending mandrel 105, which is mounted on a vertically movable mandrel holder 106 and is designed as a split mandrel. In chain link bending with a mandrel, an unsteel or slightly back-bent, rod-shaped wire segment (pin) is transported from an upstream station in the direction of arrow F (conveyor direction) to the bending mandrel. There, the pin, which may have a back bend, is pressed against the mandrel by a holding element (not shown) from the side of the bending unit and fixed in place. The circumference of the mandrel that comes into contact with the pin is shaped according to the desired inner shape of the link. During bending, the mandrel acts as a counter-holder and essentially determines the shape of the inside of the bent chain link.

[0052] The bending unit 100, which works in conjunction with the bending mandrel 105, is designed to wrap a wire element fixed to the bending mandrel around the mandrel in a bending plane to produce a bent chain link, thereby plastically deforming the wire. The bending plane corresponds to the plane in which the neutral fiber of the wire element bent into a chain link lies. The origin of the machine coordinate system can be chosen such that the bending plane coincides with the xy-plane defined by the first and second directions.

[0053] The bending unit 100 is essentially mirror-symmetrical to a median plane 122, which runs parallel to the xz plane and thus perpendicular to the bending plane through the center of the bending unit 100 and the bending mandrel 105.

[0054] The bending unit 100 comprises two sub-units that are essentially mirror-symmetrical about the central plane 122, namely one in Fig. 1 The first subunit 110-1 shown in the background and one in Fig. 1 The second subunit 110-2 is shown at the front, although the associated drives are not shown for illustrative purposes. The structure of a subunit becomes clearly apparent when viewing these two subunits together and will be explained in more detail below using the first subunit 110-1 as an example. This is shown in Fig. 2 schematically shown in a top view.

[0055] Each of the sub-units comprises a bending tool carrier unit, which carries a bending tool 148 on a component facing the bending mandrel 105. The bending tool is designed to engage the wire element. In the exemplary embodiment, both bending tool carrier units are each equipped with a bending lever 130.

[0056] The first sub-unit 110-1 has a carriage 120 that is movable parallel to the x-direction and is guided on two parallel guide rails 123 mounted on the top of the machine frame. The carriage 120 carries a bending lever 130, which is a component of the bending tool carrier unit and is pivotable within limits about a pivot axis 132 perpendicular to the bending plane at a pivot bearing of the carriage. The bending lever has a torsionally rigid S-shape and is designed as a two-armed lever such that the pivot axis 132 is located approximately midway between the lever ends, with the two lever arms at an angle of approximately 90° to 120° to each other. At its free end, which is bent inwards towards the bending mandrel 105, the bending lever 130 has a bending tool 148 in the form of a bending roller 148, which is freely rotatable on the bending lever. The axis of rotation runs parallel to the pivot axis 132.The bending roller has a concave circumferential groove that serves as a contact surface for the wire element of the chain link to be bent. The bending lever is mounted both at the top and bottom in a plate-shaped component of the slide 120, which is flat and box-shaped in this area.

[0057] After the as-yet-unbent wire element is fixed to the bending mandrel, during a bending operation the bending tools 148 (bending rollers) carried by the bending levers 130 engage the two wire ends extending laterally beyond the bending mandrel 105 and bend the corresponding pin end partially around the bending mandrel 105 in a chain link shape. The bending tools move precisely along predetermined paths around a portion of the bending mandrel. Fig. 1 A finished bent chain link KG is shown on the bending mandrel 105.

[0058] The following explains in detail how the bending unit is constructed in order to implement this path-controlled bending process with maximum flexibility regarding the path curve shape.

[0059] The linear reciprocating motion of the carriage 120 in the first direction is achieved by means of a first drive unit 140. This includes a first servo drive 142, which is mounted with its motor shaft oriented horizontally on a machine-fixed motor bearing 143. The rotation of the motor shaft is transmitted via an attached gearbox 144, in the form of a planetary gearbox, to a first cam disk 145. The first cam disk 145 is cantilevered on the output shaft of the gearbox 144, which means that all pivot bearings for supporting the first cam disk are located on the drive or gearbox side. This allows the first cam disk 145 to be positioned very close to the center plane 112. In the example case of Fig. 2 The lateral distance A1 between the center of the cam disk and a vertical plane passing through the pivot axis 132 is approximately as large as the radius of the axis or shaft that carries the bending lever.

[0060] The rotation of the first cam disk 145, generated by the first drive 142, is converted into a linear movement of the slide 120 via its outer cam flank. For this purpose, two scanning elements in the form of rollers 146-1, 146-2 are mounted on a carrier 124 fixedly connected to the slide 120, which follow the cam flank as the cam disk rotates.

[0061] The rotation of the first cam disk 145, generated by the first drive 142, is not continuous over more than 360°, but reversing, such that the cam disk moves back and forth only between a first end position and a second end position over a limited rotational angular range (less than 180°), but is not rotated indefinitely. The two scanning rollers 146-1, 146-2 are parts of a positive-locking scanning arrangement 146, with which the rotational movement of the cam disk is positively transmitted from the cam disk to the scanning arrangement connected to the slide in both directions of travel of the slide. The shape of the cam disk is such that, regardless of the rotational position, the diameter DK of the cam disk, measured on the plane of the rotational axes of the scanning rollers 146-1, 146-2, remains constant within the end positions.This ensures a backlash-free coupling between the cam and the slide in both directions of travel. The cam profile has a linear or constant slope within the operating range, which simplifies the calculation of the relationship between the rotation of the cam via the servo drive and the slide movement – ​​i.e., the transfer function between the servo drive and the slide movement.

[0062] The oscillating lifting movements of the carriage 120 in the first direction contribute to the movement of the bending rollers 148 exclusively a movement component (x-component) running in the first direction.

[0063] An analog drive configuration with a reversing drive is provided for moving the bending lever 130. The components of the second drive group 150 serve this purpose. This group comprises a second servo drive 152, which is mounted on the carriage 120 with its motor shaft oriented vertically. The reversing rotary motion of the motor shaft is transmitted via a gearbox 154, in the form of a planetary gearbox, to a second cam disk 155, which is cantilevered on the output shaft of the gearbox 154. Since no bearing is required for the cam disk on the side opposite the drive, it can be mounted with its center plane in the bending plane for optimized force transmission.

[0064] The second cam disk 155 is designed as a beaded cam with an outer and an inner cam flank. It is associated with a positive-running scanning arrangement 156 with two scanning elements 156-1 and 156-2 connected to the bending lever 130. These scanning elements are arranged at a fixed distance from each other and engage opposite sides of the circumferential bead on the cam disk. The bending lever 130 has a first scanning element 156-1 in the form of a scanning roller at its end opposite the bending roller. This roller is rotatably mounted in the bending lever and rolls on the outer cam flank of the second cam disk 155 when it rotates. The bending lever carries a second scanning element 156-2 in the form of a scanning roller, which simultaneously rolls on the inner cam flank. This ensures backlash-free engagement of the bending lever in every rotational position of the cam disk, regardless of the direction of rotation.

[0065] The bending lever 130 has a multi-part construction. The lever arm leading to the scanning roller 156 and the part of the lever arm closer to the pivot axis 132, which carries the bending roller 148, remain unchanged for all chain link geometries within the working range. The outer part 133 of the lever arm, which carries the bending roller 148, is attached to the remaining part at an interface 134 by means of fastening screws and can be easily replaced to adapt to a different bending geometry and / or different wire diameters.

[0066] The working movements of the bending lever 130 generated via the second servo drive 152 have a predominantly positive effect as movement components of the bending rollers 148 in the second direction (y-direction) and to a lesser extent also with components in the first direction perpendicular to it.

[0067] The first servo drive 142 and the second servo drive 152 are each connected to the control unit 190 of the chain bending machine, so that the movement characteristics of the connected cam discs can be precisely controlled by the position control, speed control and / or torque control of the respective servo drive.

[0068] This concept enables the generation of freely programmable movements of the bending tools of the chain bending machine. All four servo drives for the machine axes (linear axis with slide, rotary axis for bending lever) are electrically connected to a control unit 190, which contains, among other things, the power supplies and position detection of the drives, a central processing unit, and storage units. Using the control software active in the control unit, the movements of all machine axes can be variably controlled based on setting parameters. This allows the trajectories along which the bending rollers are to run to be freely specified by programming within design-related limits.

[0069] A display and operating unit 195 connected to the control unit 190 serves as an interface to the machine operator. The operator can enter certain parameters relevant to the bending process, such as the desired chain link geometry (geometry data), various workpiece properties (workpiece data), and tool data, at an input unit 196 of the operating unit before the bending process begins. In this example, the input unit 196 comprises a touch-sensitive screen (touchscreen).

[0070] The control unit 190 is a central component of the freely programmable bending path control system of the chain bending machine 200. With this system, different path curves of the bending tools can be specified by entering input parameters at an input unit via the control unit 190.

[0071] The bending process control system is programmed by a machine operator via the display and control unit 195. Programming can proceed as follows, for example.

[0072] The starting point for the programming is the dimensions of the chain link to be bent. Fig. 4 Figure 1 shows an example of field F in an input mask, which schematically depicts a bent chain link KG together with associated input windows for entering the geometry data. The input parameters include the wire diameter d, the inner pitch tb of the bent chain link (i.e., the clear distance between the inner chain loops in the longitudinal direction), the outer width bb2 of the chain link, and, if applicable, the residual cross-section k that should remain at the facing ends of the wedge-shaped split pins for the subsequent chain welding process, as well as the angle (opening angle) of the notch, the input field of which is shown in Figure 2. Fig. 4 as indicated by the ° symbol.

[0073] The control system calculates the tine length from the geometry data. Based on this, it also determines the positions of various machining stations on the machine bed, such as the position of the notching unit, as well as the axis movements, such as the feed movement required for the calculated tine length. The calculated axis movements follow a pre-configured sequence stored in the control system, which describes the machine's operational sequence for setting up and producing the chain. The positions of the machining stations are displayed to the operator and must be set manually. In other embodiments, the workstations are positioned by their own positioning drives.

[0074] The tool geometries for the tools to be used by the operator are calculated from the input data and the design rules stored in the control system. This applies, for example, to the feed rollers of the feed units 910 and 920, sometimes to the straightening rollers of the straightening unit 915, possibly to a punch tool, to embossing plates in the back bending functional group, to notching knives of the notching unit 940, to cutting bushings and counter-holders in the cutting station 950, to transport jaws for the pin transport, to the bending mandrel and a holding mandrel, and to the bending rollers. Deviating dimensions of these tools can be adjusted by the operator and are taken into account in the calculations.

[0075] Based on this, the bending paths are calculated. These can be influenced by the operator, for example, to correct elastic deflection. Starting with the bending paths, the electronic cam profiles for the individual axes are generated. Here, the term "cam profile" refers to a unique assignment between a master drive and a follower drive. An electronic cam profile can, for example, be in the form of a table of reference points with target position values ​​for the follower drive over time, i.e., in the form of a displacement-time diagram for the follower drive.

[0076] For the bending process, a virtual cam is created for each side of the bending station (left and right sub-units). In a subsequent calculation step, the X- and Y-axis movements required to generate the bending path are calculated and coupled to the virtual cam.

[0077] One advantage of this approach is that, by coupling the bending path, it is also possible to use the process for monitoring and control during setup (at a significantly reduced speed compared to production operation).

[0078] Preferably, the calculation is performed under the boundary condition that the point of application between the tool (bending roller) and the workpiece (wire or wire pin) remains unchanged during the bending operation, so that no relative movement occurs between the bending tool and the wire and optimal force ratios exist in every phase of the bending operation. This allows for optimized protection of the wire material even under high forces.

[0079] This path-controlled bending process can be used within the working area of ​​the chain bending machine with the same mechanical equipment for numerous different chain link geometries. For a format change (i.e., a change to a different chain link geometry), only the bending mandrel and, if necessary, the bending rollers—i.e., only the wire-contacting components—need to be replaced. The other components of the bending unit, especially the cam discs, do not need to be changed. This reduces the number of interchangeable components to a minimum, significantly reducing assembly, setup, and adjustment times compared to conventional solutions. At the same time, it offers considerable freedom regarding the chain link shape, as the bending rollers can be guided around the bending mandrel on almost any path.

[0080] The bending of the chain link can be done either in a single bending step (straight tiller => fully bent chain link) or in a two- or multi-stage bending process. In the multi-stage process, for example, the straight tiller is first pre-bent into a U-shape, then the first leg is bent, and finally the second leg is bent.

[0081] The examples shown illustrate the processing of round wire, i.e., wire with a circular cross-section. Wires with other cross-sectional profiles, such as D-profiles, can also be processed. For this, some or all of the tools in contact with the workpiece may need to be designed accordingly.

[0082] To ensure consistently high quality and prevent rejects, the chain bending machine 200 is equipped with a monitoring system for overseeing its operation and detecting malfunctions. This monitoring system allows for the early detection of emerging problems, enabling corrective action before minor defects in any of the functional units significantly impact the quality of the chain links. Preferably, the monitoring system includes a drive monitoring subsystem that can detect and display overload situations caused by malfunctions. This drive monitoring subsystem is designed to record the torque curves of the individual machine drives on the machine axes.Adjustable envelopes enable the detection and prevention of machine and tool overloads caused, for example, by material and / or tool breakage or collisions during setup. The monitoring system can be configured to automatically stop operation if the drive monitoring subsystem detects a significant overload problem. The system then indicates which drive experienced the excessive machine torque that triggered the shutdown, allowing the operator to quickly identify the precise cause of the malfunction and rectify it, for example, by replacing a worn tool.

[0083] The monitoring system of the 200 chain bending machine also includes a subsystem for monitoring the notch depth of the notches produced using the 940 notching unit. Broken or worn notching blades can lead to insufficiently deep notches, which subsequently cause problems during chain welding. By the time this is noticed in the process, several meters of chain may have been produced, which are then considered scrap. A notch depth monitoring subsystem allows developing problems to be detected in a timely manner.

[0084] In the exemplary system of Fig. 1 Optical measurement of the notch point using camera 945 is provided for this purpose. Alternatively or additionally, a system for determining the force required to shear the wire pin can also be provided. Insufficient notch depth increases the required shear force. Monitoring the motor torque of the machine axis that operates the shearing device 950 can therefore indicate problems with insufficient notch depth in the notching device 940. The shear force can be determined at the shearing device 950, for example, via the required drive torque or via a separate force sensor.

[0085] A monitoring system for a chain bending machine can also be advantageous for other chain bending machines, independent of the other features of the exemplary chain bending machine described, for example, for those whose bending station is constructed differently than in the exemplary embodiment of Fig. 1 .

Claims

1. Chain-bending machine (200) for producing chains with bent chain links, having a bending station (210) comprising: a bending mandrel (105); a bending unit (100) for producing a bent chain link (KG) by bending a wire element around the bending mandrel (105) in a bending plane; wherein the bending unit (100) has two sub-units (110-1, 110-2), which are arranged on opposite sides of a centre plane (122) of the bending unit (100), the centre plane being perpendicular to the bending plane, wherein each of the sub-units (110-1, 110-2) has a bending-tool-carrier unit, which, on a component facing the bending mandrel, carries a bending tool (148) for acting on the wire element, wherein the bending tools (148) can be moved on predefinable paths around the bending mandrel (105) during the bending process; characterized by a freely programmable bending-progression-control system, which is configured such that different progressions of paths taken by the bending tools (148) can be predefined by input parameters being input at an input unit (196) of the bending-progression-control system via a control unit (190), wherein each of the sub-units (110-1, 110-2) has a carriage (120), which is displaceable in a first direction parallel to the centre plane (122) and on which a further component of the bending-tool-carrier unit is mounted, wherein the further component is a bending lever (130) of the sub-unit or a carriage of a cross table, and wherein a first drive group (140) for moving the carriage has a first servo drive (142), which is connected to the control unit (190), and a second drive group (150) for moving the further component has a second servo drive (152), which is connected to the control unit (190).

2. Chain-bending machine according to Claim 1, characterized in that the bending-progression-control system is configured such that geometry data relating to the chain link to be manufactured can be input in the form of input parameters at the input unit (196), and in that the bending-progression-control system is configured to perform specific calculations based on the geometry data for the chain link, wherein preferably the bending-progression-control system is configured such that a field of an input mask can be generated on a display device of the operating unit (195), and a bent chain link together with input fields for the associated geometry data is presented in the input mask.

3. Chain-bending machine according to Claim 2, characterized in that the calculations specific to the chain link include one or more of the following calculations: (i) calculation of the pin length; (ii) calculation of tool geometries; (iii) calculation of the paths taken by the bending tools.

4. Chain-bending machine according to one of the preceding claims, characterized in that the bending-tool-carrier unit has a bending lever (130), which can be pivoted about a pivot axis (132), running perpendicularly to the bending plane, and which carries the bending tool (148) at its free end, which faces the bending mandrel (105) .

5. Chain-bending machine according to one of the preceding claims, characterized in that the second servo drive (152) of each sub-unit is carried by the carriage (120).

6. Chain-bending machine according to one of the preceding claims, characterized in that the first drive group (140) has a first cam disc (145), which is coupled to the first servo drive (142), and / or the second drive group (150) has a second cam disc (155), which is coupled to the second servo drive (152).

7. Chain-bending machine according to Claim 6, characterized in that the control unit (190) is configured such that the first cam disc (145) and / or the second cam disc (155) are / is reversingly driven between a first end position and a second end position.

8. Chain-bending machine according to Claim 6 or 7, characterized in that the first cam disc (145) and / or the second cam disc (155), in accordance with the intended use, are / is non-interchangeable and geometrically designed such that they / it can be used in an unaltered state for all bending operations within the working region of the chain-bending machine.

9. Chain-bending machine according to Claim 6, 7 or 8, characterized in that the first cam disc (145) and / or the second cam disc (155) have / has a curve shape with a linear gradient or an exponential-function gradient.

10. Chain-bending machine according to Claim 6, 7, 8 or 9, characterized in that the first cam disc (145) is assigned a positive-guidance follower arrangement (146) with two follower elements (146-1, 146-2), which are connected to the carriage and are arranged at a fixed distance from one another and act on opposite cam-flank portions of the cam disc, and / or in that the second cam disc (155) is assigned a positive-guidance follower arrangement (156) with two follower elements (156-1, 156-2), which are connected to a further component of the bending-tool-carrier unit, in particular to the bending lever (130), and are arranged at a fixed distance from one another and act on opposite cam-flank portions of the cam disc.

11. Chain-bending machine according to one of Claims 5 to 10, characterized in that the first servo drive (142) is coupled to the first cam disc (145) via a first gear mechanism, wherein the first cam disc is floatingly mounted on an output shaft of the first gear mechanism, and / or in that the second servo drive (152) is coupled to the second cam disc (155) via a second gear mechanism, wherein the second cam disc is floatingly mounted on an output shaft of the second gear mechanism.

12. Chain-bending machine according to one of the preceding claims, characterized in that the chain-bending machine is equipped with a monitoring system for monitoring the operation of the chain-bending machine and for ascertaining malfunctions, wherein the monitoring system preferably has at least one of the following subsystems: a drive-monitoring sub-system, which can detect and display malfunction-induced overload situations; a sub-system for monitoring the notch depth of notches produced with the aid of a notch-making device of the chain-bending machine.