EP3978159B1 - Chain bending machine for making a chain - Google Patents

Description

FIELD OF APPLICATION AND STATE OF THE ART

The invention relates to a chain bending machine for producing chains with bent chain links.

Chains with chain links bent from wire elements in a forming process are now manufactured on a large scale using special automated machine tools, which are usually referred to as chain bending machines or chain manufacturing machines, or occasionally simply as chain machines.

Chains are usually manufactured in two main processes: bending - usually called chain bending - and welding - usually called chain welding. During chain bending, chain links are bent from initially straight wire elements of a suitable length, so-called pins, and connected to other chain links, which can also be bent from wire elements or manufactured in another way, e.g. by forging. During subsequent chain welding, the fully bent, still open chain links of a chain strand are welded to form closed chain links, e.g. using a suitable resistance butt welding process.

This application relates to the bending of chain links 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 wire supply. The length of the piece of wire corresponds to the length of the desired chain link plus additional welding allowance. The pin is pressed against a bending mandrel by a holding element and thus fixed. The bending mandrel is designed on its circumference according to the desired inner shape of the link. After fixing, a corresponding bending tool grips the two wire ends that protrude beyond the bending mandrel and bends the corresponding end of the pin partially around the bending mandrel into the shape of a chain link.

The disclosure document 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 which are arranged on opposite sides a central plane of the bending unit that is perpendicular to the bending plane. The central plane runs through the middle of the bending mandrel. Each of the two sub-units has a bending lever that can be pivoted about a pivot axis that runs perpendicular to the bending plane. The pivot axis can be moved linearly. Each bending lever has a bending tool in the form of a pivoting bending roller that is movably mounted on the bending lever at its free end facing the bending mandrel, for engaging the wire element. During bending, the bending tools are moved around the bending mandrel on predeterminable trajectories. The bending rollers are guided by guide rollers that are guided in grooves. These grooves are provided in a body that is rigidly connected to the bending mandrel to form a replaceable block. This has the advantage that the bending mandrel and the grooves can be adjusted outside of the machine. Because guide rollers, rather than the bending rollers themselves, run in the grooves, the bending rollers can roll on the pin, which significantly reduces wear.

The disclosure document DE 2 531 290 A1 describes a method for bending chain links from wire pins of a given 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 the free ends of the pins, which is guided on a curved path during the bending process in such a way that the contact point of the bending tool on the wire pin runs approximately on an involute of a circle, at least in the end area of the bending process, 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 move during the bending process, so that no grinding or rolling marks are created on the pin surface.

The 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 which can be moved in the direction of the bending mandrel or in the opposite direction using a hydraulic main cylinder. The carriage carries a further hydraulic cylinder on each side of the main cylinder. Each of these further 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 that they can pivot about vertical pivot axes and are coupled to one another via a swivel joint. This design allows the bending tools to bend on predetermined trajectories around the Bending mandrel can be moved. The hydraulic cylinders can be controlled via a programmable logic controller.

Chain bending machines should be able to cover the widest possible range of chains, in particular a large range of wire diameters, a wide variety of chain link geometries, a wide variety of bending radii, a wide variety of materials, etc. The set-up times should be reduced as much as possible so that a changeover to new chain link geometries can be carried out with the least possible mechanical conversion effort.

TASK AND SOLUTION

Against this background, the invention is based on the object of providing a chain bending machine of the type mentioned at the outset, in which, in comparison with conventional solutions, Set-up and adjustment times are reduced when changing between different chain link geometries. In particular, increased operator safety and increased operating comfort should also be provided.

To achieve this object, the invention provides, according to one formulation, a chain bending machine with the features of claim 1. Advantageous further developments are specified in the dependent claims. The wording of all claims is made part of the content of the description by reference.

The chain bending machine is designed to produce chains with bent chain links. When set up, it includes a bending mandrel. The bending mandrel is usually designed to match the desired inner link shape. It can be a split bending mandrel or an undivided bending 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 bending plane, which here means, among other things, that the neutral fiber of the bent wire element lies with all sections in a single plane. The bending unit has two sub-units. The sub-units are arranged on opposite sides of a center plane of the bending unit that is perpendicular to the bending plane. The bending unit can be constructed more or less mirror-symmetrically to the center plane, so that the two sub-units also have a comparable structure.

Each of the sub-units comprises a bending tool carrier unit which carries a bending tool on a component facing the bending mandrel, which is intended to engage the wire element. The bending tool is therefore the part of the bending unit which comes into contact with the wire material on the corresponding side of the bending mandrel. The bending tools are movably mounted on the components of the respective bending tool carrier unit that carry them. This mobility is provided so that the bending tool can align itself optimally with the workpiece at all times during the bending movement or during the gradual deformation of the wire around the bending mandrel. The bending tools can be moved around the bending mandrel on predeterminable trajectories during bending with the help of the bending tool carrier unit. The trajectories of the bending tools only extend around part of the circumference of the bending mandrel.

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 Path curves of the bending tools can be specified by entering input parameters on an input unit of the bending process control system via a control unit of the chain bending machine. The "free" programmability is of course only available within the design-specified limits, so that not just any path curves can be specified, but a large variety of different path curves can be created within the design-specified limits. This means that different path curves of the bending tools can be set using programming alone, i.e. on the software side, so that a completely software-based path curve control is provided for the movements of the bending tools.

The input unit can be located on or near the chain bending machine. For example, a touch screen in conjunction with a PC and corresponding software can be provided for displays and inputs in plain text. Input at a remote location, possibly in another room or another building, is also possible if required.

One advantage of this concept is that, with the exception of the wire-contacting components (in particular the bending mandrel and possibly bending tools and possibly other geometry-dependent tools such as clamps, turning jaws, pincer transport gripper jaws etc.), no other components of the chain bending machine need to be replaced when changing between different chain link geometries. The "conversion" can therefore be carried out to a large extent by means of programming, i.e. via software. For example, in comparison to the solution of the 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. In comparison to conventional drive concepts with mechanical cam drives with guide shafts, it is also no longer necessary to change cam disks or cam inserts for assembling multi-part cam disks. The chain bending machine can therefore be quickly and easily converted to different chain link dimensions within its working range, which can be characterized by the wire diameters that can be processed, among other things. During the conversion, it may only be necessary to replace wire-contacting components with corresponding wire-contacting components of a different geometry. This results in considerable reductions in assembly times and reductions in set-up and adjustment times. In addition, operator safety and operating comfort are improved compared to conventional solutions. Furthermore, the mechanical complexity can be reduced compared to conventional solutions.

In some embodiments, the bending process control system is configured such that geometry data of the chain link to be manufactured can be entered as input parameters on the input unit and that the bending process control system is configured to carry out specific calculations for the chain link based on the geometry data. In some embodiments, the geometry data or the 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 arches in the longitudinal direction), the outer width of the chain link and, if applicable, the remaining cross-section that is to remain at the mutually facing ends of wedge-shaped separated pins for the subsequent chain welding process.

In order to make input easier for the operator and to illustrate the meaning of the input parameters, the bending process 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 shown together with input fields for the associated geometric data.

The chain link specific calculations may include one or more of the following calculations: calculation of the pin length; calculation of tool geometries; calculation of the trajectories of the bending tools.

Based on the pin length information, the positions of the individual processing stations on the machine bed can be determined. Depending on the expansion stage of the chain bending machine, these can then be adjusted manually or automatically using suitable machine axes.

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

Based on this, the bending paths or trajectories of the bending tools can be calculated.

The bending tools are preferably bending rollers mounted rotatably on the respective bending tool carrier unit, which roll on the wire without damaging the wire surface in the event of any relative movement between the circumference of the bending roller and the wire to be bent. The calculation of the trajectories is preferably carried out under the boundary condition that the point of application between the bending tool and Wire is kept unchanged during the bending operation, so that no relative movement results between the bending tool and the wire and optimal force ratios are present in every phase of the bending operation. In these cases in particular, other bending tools can be used as an alternative to bending rollers. For example, bending shoes can be provided instead of bending rollers in order to obtain a larger contact surface instead of the linear contact (which is the case with bending rollers), thus reducing the local surface pressure.

There are different ways of designing a bending tool carrier unit. In some variants according to the claimed invention, each of the bending tool carrier units has a bending lever that can be pivoted about a pivot axis running 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 a bending lever can have a very compact structure and can safely transmit large forces. The pivoting bending lever can also be moved linearly parallel to the bending plane, so that the bending tool can be guided along different trajectories using a combination of linear displacement and pivoting movement parallel to the bending plane.

Alternatively, in other variants according to the claimed invention, it is provided that a bending tool carrier unit has a cross table (also called an XY table), i.e. a two-axis system that has two single-axis linear guide systems and which thus enables a bending tool to be moved in two directions within the bending plane. The bending tool can thus be guided along different trajectories parallel to the bending plane via a combination of two mutually orthogonal linear displacements.

According to another embodiment, a bending tool carrier unit has two coupled linear units that are pivotably attached to the machine frame on pivot axes. The pivot axes are aligned parallel to one another, but laterally offset from one another in such a way that one linear unit moves essentially parallel to a first direction and the other linear unit moves essentially in a second direction that is orthogonal to the first direction. The linear units each have extendable end pieces, the ends of which are coupled to one another and carry the bending tool in the area of the coupling. By extending and retracting the two linear units in a controlled manner, it is possible to move the bending tool on practically any trajectory in the plane of movement (parallel to the bending plane).

In the variant according to the invention with bending levers, it is provided that each of the sub-units has a carriage that can be moved in a first direction parallel to the center plane and on which the bending lever of the sub-unit is mounted so as to be rotatable about the pivot axis, with a first drive group for moving the carriage having a first servo drive and a second drive group for moving the bending lever having a second servo drive, which is preferably carried by the carriage. With the help of this structure, almost any trajectory 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 in the first direction, the amount of which can be controlled as a function of time using the first servo drive. The second drive group moves the bending lever and thus controls movement components of the bending tools that run within the bending plane perpendicular to the first direction or perpendicular to the center plane. The movements generated by the servo drives of the sub-units are coupled electronically via the control unit.

The second servo drive is preferably a moving drive that moves 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. It would also be conceivable to install the second servo drive in a stationary position and to couple it to the bending lever via a flexible shaft or another flexible transmission device (e.g. cardan shaft with length compensation).

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

Particularly preferred are variants in which the first drive group has a first cam disk coupled to the first servo drive and/or the second drive group has a second cam disk coupled to the second servo drive. The servo drives are therefore each used to drive cam disks in rotation. This creates servomechanical drive groups. This allows movements of an output shaft of the servo drive to be transmitted mechanically unevenly (with a variable transmission function) to the respective driven component via a cam gear, with the transmission function being specified by the course of the cam flank or the curve shape of the cam disk. The combination of servo drives with cam disks allows a favorable design both with regard to the very high forces sometimes required during bending and with regard to the dynamics of the bending operation, i.e. the speed profiles of the tool movements.

In the variant with bending levers, the first drive group with the first servo drive and the first cam disk generates the linear back and forth movement of the carriage, which carries the bending lever of the sub-unit 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.

Particularly advantageous are embodiments in which the control unit is configured in such a way that the first cam disk and/or the second cam disk is driven in reversing fashion between a first end position and a second end position. In contrast to conventional cam drives with a uniformly rotating drive movement, the cam disk is rotated back and forth in opposite directions of rotation with a limited angle of rotation. The end positions define the limits of the transfer function implemented by the cam disk. The mechanical complexity can be reduced compared to uniformly rotating drive movements.

In contrast to conventional solutions, where cam disks were replaced with cam disks with a different curve shape and different strokes when changing between different chain link geometries, with a reversing drive or with cam disks designed for a reversing drive, it is not necessary to replace cam disks when changing formats. The cam disks can be designed in such a way that they can be used unchanged for all operations within the working range of the chain bending machine and only need to be replaced if they wear out. The curve shape of the cam disk can therefore be defined once for all chain link geometries in the working range. This means that special design measures that enable cam disks to be changed easily are no longer necessary, so that the transmission coupling between the servo drive and the cam disk can be designed to be particularly stable mechanically and suitable for the transmission of high forces or torques.

In some embodiments with reversing drive of cam disks, the first cam disk and/or the second cam disk has a curve shape with a linear gradient. This means that in the rotation angle range between the first end position and the second end position, the radial distance between the center of rotation of the cam disk and the outer curve flank changes according to a linear function. It has been shown that this can significantly reduce the computational effort for controlling the connected servo drive compared to variants in which complicated non-linear relationships between the angle of rotation and the curve position are determined by the shape of the curve flank. is specified. Alternatively, gradients can be used that can be described with an e-function. However, variable gradients are also possible.

In variants with a reversing drive of the first cam disk, according to a further development, a positive motion scanning arrangement with two scanning elements connected to the carriage is assigned to the first cam disk, whereby the scanning elements, which are implemented for example by scanning rollers, are arranged at a fixed distance from one another and act on opposite curve flank sections of the cam disk. In the reversing operating mode and limited angles of rotation of less than 180° between the end positions, the curve shape can be designed in such a way that in all rotation positions within this working range, the distance measured between the scanning elements between associated curve flank sections is always the same, regardless of the rotation position. As a result, the carriage is driven both in its forward movement and in its backward movement via the correspondingly arranged scanning elements and a play-free conversion of the cam disk rotation into the linear carriage movement is possible.

In variants with a reversing drive of the second cam disk, according to a further development, it can be provided that the second cam disk is assigned a positive-motion scanning arrangement with two scanning elements connected to the bending lever (or another carriage), wherein the scanning elements, which are realized for example by scanning rollers, are arranged at a fixed distance from one another and act on opposite curve flank sections of the cam disk.

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

In preferred embodiments, an arrangement between the servo drive and the driven component that is favorable in terms of installation space requirements and power transmission is achieved by the fact that the first servo drive is coupled to the first cam disk via a first gear, with the cam disk being cantilevered on an output shaft of the gear. Cantilevered mounting here means that no mounting is provided for the cam disks on the side opposite the gear. The drive group can have a straight, elongated structure, at one end of which the cantilevered cam disk is is arranged. The floating bearing makes it possible to arrange the cam disk in or near the plane in which the pivot axis of the bending lever is located and in which the force of the movement component transmitted via the slide movement is transmitted. This results in a reduction in possible transverse forces on the components under load during bending, which also benefits the precision of the trajectory curve, among other things.

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 disk via a second gear, with the second cam disk being cantilevered on the output shaft of the gear. This makes it possible to arrange the cam disk in relation to the bending lever so that they lie in a common plane. This ensures optimal power transmission for pivoting the bending lever.

In order to ensure that the quality of the bent chain links is as consistent as possible and to avoid the production of rejects as far as possible, a monitoring system is provided to monitor the operation of the chain bending machine and to identify operational faults. The monitoring system preferably includes a drive monitoring subsystem that can detect and display overload situations caused by faults. The drive monitoring subsystem can be designed to record the time profiles of the motor torques of the individual machine drives of the machine axes and to compare them with permissible value ranges, which can be in the form of envelope curves. If a situation defined as significant occurs, operation can be stopped automatically in order to be able to remedy the situation.

Fig. 1

zeigt eine schematische Seitenansicht einer Kettenbiegemaschine gemäß einer Ausführungsform;

Fig. 2

zeigt eine schematische isometrische Darstellung von Komponenten einer Biegestation einer Kettenbiegemaschine gemäß einem Ausführungsbeispiel;

Fig. 3

zeigt schematisch in Draufsicht eine erste Teileinheit der Biegeeinheit aus Fig. 1;

Fig. 4

zeigt einen Ausschnitt aus einem Feld der Eingabemaske, in welchem schematisch ein gebogenes Kettenglied dargestellt ist.

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 an embodiment;

Fig. 2

shows a schematic isometric representation of components of a bending station of a chain bending machine according to an embodiment;

Fig. 3

shows schematically in plan view a first sub-unit of the bending unit from Fig. 1 ;

Fig. 4

shows a section of a field of the input mask, in which a curved chain link is schematically shown.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The schematic side view in Fig. 1 shows an exemplary embodiment of a chain bending machine 200 for producing chains that have chain links bent from wire material. The chain bending machine has a large number of functional units that are mounted in a straight row on a machine frame 202. For orientation, a Cartesian machine coordinate system MK is shown. Its x-direction runs horizontally in the example and is also referred to here as the first direction. The y-direction, which is perpendicular to this and is also horizontal in the example, is also referred to as the second direction. The z-direction points vertically in this orientation.

A first feed device 910 serves together with a downstream second feed device 920 to feed the wire DR from a wire supply, which is typically in the form of a coil, i.e. a wire bundle wound up like a spool. The feed devices 910, 920 each have a pair of feed rollers driven in opposite directions (roller feed).

Between the feed devices, a straightening unit 915 with two roller straightening devices connected in series is arranged, each of which has 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 one another.

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.

An optional wire stamping device 930 is provided immediately downstream of the length measuring device, with which a logo, lettering, number or the like can be stamped into the wire at predetermined locations on the wire being conveyed through. In other embodiments, this optional component is not provided.

A back bending device 935 is arranged behind it in the wire feed direction, with which a back bend can be created on the wire.

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.

A downstream shearing station or cutting station 950 is used to cut off a piece of wire DS or a pin of a predetermined length from the supplied wire at the notched location.

A downstream transport device 955 (also called pin transport) serves to feed the pins to the downstream bending station 210, the structure and function of which is described, among other things, in connection with the Fig. 2 and 3 will be described in more detail. Fig. 2 shows a schematic isometric representation of some components of the bending station 210. Fig. 3 shows a schematic plan view of a first sub-unit of a bending unit of the bending station.

All controllable components of the chain bending machine 200 are connected to the control unit 190 of the chain bending machine, which contains, among other things, the power supplies and position detection of the drives, a central processing unit and storage units. With the help of the control software active in the control unit, the movements of all machine axes can be variably controlled based on setting parameters. A display and operating unit 195 connected to the control unit 190 serves as an interface to the machine operator.

The chain bending takes place automatically in the bending station 210 using a so-called bending mandrel 105, which is mounted on a vertically movable bending mandrel holder 106 and is designed as a split bending mandrel. When bending chain links with a bending mandrel, a rod-shaped piece of wire (pin) that has not yet been bent or has a slight back bend is transported from an upstream station in the direction of arrow F (conveying direction) to the bending mandrel. There, the pin, which may have a back bend, is pressed onto the bending mandrel by a holding element (not shown) from the side of the bending unit and fixed there. The circumference of the bending mandrel that comes into contact with the pin is designed according to the desired inner shape of the link. The bending mandrel serves as a counterholder during bending and essentially determines the shape of the inside of the bent chain link.

The bending unit 100, which works together with the bending mandrel 105, is designed to wind a wire element fixed to the bending mandrel around the bending mandrel in a bending plane to produce a bent chain link and to plastically deform it in the process. The bending plane corresponds to the plane in which the neutral fiber of the wire element to be formed into a chain link bent wire element. The origin of the machine coordinate system can be chosen so that the bending plane coincides with the xy plane spanned by the first and second directions.

The bending unit 100 is constructed essentially mirror-symmetrically to a center plane 122, which runs parallel to the x-z plane and thus perpendicular to the bending plane through the center of the bending unit 100 and the bending mandrel 105.

The bending unit 100 comprises two sub-units constructed essentially mirror-symmetrically to the central plane 122, namely a Fig. 1 First sub-unit 110-1 shown in the back and one in Fig. 1 The second sub-unit 110-2 shown at the front, where the associated drives are not shown for illustration purposes. The structure of a sub-unit is clearly visible when these two sub-units are viewed together and is explained in more detail below using the first sub-unit 110-1. This is shown in Fig. 2 shown schematically in plan view.

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, which is intended to engage the wire element. In the exemplary embodiment, the two bending tool carrier units are each equipped with a bending lever 130.

The first sub-unit 110-1 has a carriage 120 that can be moved parallel to the x-direction and is guided on two parallel guide rails 123 that are 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 can be pivoted to a limited extent on a pivot bearing of the carriage about a pivot axis 132 that runs perpendicular to the bending plane. The bending lever has a torsion-resistant S-shape and is designed as a two-armed lever in such a way that the pivot axis 132 is located approximately centrally between the lever ends, with the two lever arms being at an angle of approximately 90° to 120° to one another. The bending lever 130 has a bending tool 148 in the form of a bending roller 148 on its free end that is bent inwards towards the bending mandrel 105, which is freely rotatably mounted on the bending lever. The rotation axis runs parallel to the pivot axis 132. The bending roller has a concave circumferential groove which is intended as an engagement surface for contact with the wire element of the chain link to be bent. The bending lever is mounted both at the top and at the bottom in a plate-shaped component of the carriage 120, which is flat in this area and is box-shaped.

After fixing the not yet bent wire element to the bending mandrel, the bending tools 148 carried by the bending levers 130 grip (bending rollers) on the two wire ends that protrude laterally beyond the bending mandrel 105 and bend the associated pin end partially around the bending mandrel 105 into a chain link shape. The bending tools move precisely along predetermined trajectories around a part of the bending mandrel. In Fig. 1 a finished bent chain link KG is shown on the bending mandrel 105.

The following explains how the bending unit is constructed in detail in order to realize this path-controlled bending process with a maximum degree of flexibility regarding the trajectory shape.

The linear back and forth movement of the carriage 120 in the first direction is achieved by means of a first drive group 140. This comprises a first servo drive 142, which is mounted with its motor shaft horizontally oriented on a motor bearing 143 fixed to the machine. The rotation of the motor shaft is transmitted to a first cam disk 145 via a connected gear 144 in the form of a planetary gear. The first cam disk 145 is cantilevered on the output shaft of the gear 144, which here means that all pivot bearings for supporting the first cam disk are arranged on the drive or gear side. This makes it possible to move the first cam disk 145 very close to the center plane 112. In the example 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 carrying the bending lever.

The rotation of the first cam disk 145 generated by the first drive 142 is converted into a linear movement of the carriage 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 that is firmly connected to the carriage 120, which follow the cam flank when the cam disk rotates.

The rotation of the first cam disk 145 generated by the first drive 142 is not continuous over more than 360°, but reversing in such a way that the cam disk only moves back and forth between a first end position and a second end position reversing over a limited angle of rotation range (less than 180°), but is not rotated indefinitely. The two scanning rollers 146-1, 146-2 are parts of a positive scanning arrangement 146, with which the rotary movement of the cam disk in both directions of travel of the carriage is positively transferred from the cam disk to the scanning arrangement connected to the carriage. The shape of the cam disk is such that, regardless of the rotational position within the end positions of the diameter DK of the cam disc measured at the level of the rotation axes of the scanning rollers 146-1, 146-2 is constant. This creates a play-free coupling between the cam disc and the slide in both directions of travel of the slide. The curve shape has a linear or constant gradient in the working range used, which makes the calculation of the relationship between the rotation of the cam disc by means of the servo drive and the slide movement, i.e. the transfer function between the servo drive and the slide movement, particularly easy.

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

An analog drive configuration with a reversing drive is provided for moving the bending lever 130. The components of the second drive group 150 are used for this purpose. This includes a second servo drive 152, which is mounted on the carriage 120 with its motor shaft oriented vertically. The reversing rotary movement of the motor shaft is transmitted via a gear 154 in the form of a planetary gear to a second cam disk 155, which is cantilevered on the output shaft of the gear 154. Since no bearing is required for the cam disk on the side facing away from the drive, it can be mounted with its center plane in the bending plane for optimized power transmission.

The second cam disk 155 is designed as a beaded cam with an outer cam flank and an inner cam flank. It is assigned a positive motion scanning arrangement 156 with two scanning elements 156-1, 156-2 connected to the bending lever 130, which are arranged at a fixed distance from one another and engage on 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, which is rotatably mounted in the bending lever and rolls on the outer cam flank when the second cam disk 155 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, so that play-free movement of the bending lever is ensured in every rotational position of the cam disk, regardless of the direction of rotation.

The bending lever 130 is constructed in several parts. The lever arm leading to the scanning roller 156 and the part of the lever arm that is closer to the pivot axis 132 and that carries the bending roller 148 remain unchanged for all chain link geometries within the working area. The outer part 133 of the lever arm that carries the bending roller 148 is secured by means of fastening screws replaceably attached in the area of an interface 134 on the remaining part and can be easily replaced to adapt to a different bending geometry and/or other wire diameters.

The working movements of the bending lever 130 generated via the second servo drive 152 predominantly act as movement components of the bending rollers 148 in the second direction (y-direction) and to a small extent also with components in the first direction perpendicular thereto.

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 cam disks connected to it can be precisely controlled by the position control, speed control and/or torque control of the respective servo drive.

This concept enables the creation 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 computer unit and storage units. With the help of the control software active in the control unit, the movements of all machine axes can be variably controlled based on setting parameters. This means that the trajectories along which the bending rollers are to run can be freely specified by programming within design-related limits.

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, e.g. the desired chain link geometry (geometry data), possibly various workpiece properties (workpiece data) and tool data, on an input unit 196 of the operating unit before the bending process begins. In the example case, the input unit 196 comprises a touch-sensitive screen (touchscreen).

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

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

The starting point for programming is the dimensions of the chain link to be bent. Fig. 4 shows an example of a field F of an input mask in which a bent chain link KG is shown schematically together with the 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 arches in the longitudinal direction), the outer width bb2 of the chain link and, if applicable, the remaining cross-section k that is to remain at the mutually facing ends of the wedge-shaped pins for the subsequent chain welding process, as well as the angle (opening angle) of the notch, the input field of which is in Fig. 4 can be identified by the ° sign.

The control system calculates the pin length from the geometry data, and the positions of various processing stations on the machine bed are based on this, such as the position of the notching device, as well as the axis movements, such as the feed movement required for the calculated pin length. The calculated axis movements take place according to a preconfigured sequence stored in the control system, which describes the functional sequence of the machine for setting up and producing the chain. The positions of the processing stations are displayed to the operator and must be set manually by him. In other embodiments, the work stations are positioned by their own positioning drives.

The tool geometries of the tools to be used by the operator are then calculated from the input data and the design rules for the tools stored in the control system. This applies, for example, to the feed rollers of the feed devices 910, 920, sometimes to the straightening rollers of the straightening unit 915, possibly to a stamping tool, to embossing plates in the functional group for back bending, to notching knives of the notching device 940, to cutting bushes and counterholders in the separating station 950, to transport jaws for the pin transport, to the bending mandrel and a holding mandrel as well as to the bending rollers. Different dimensions of these tools can be adjusted by the operator and are taken into account in the calculations.

Based on this, the bending paths are calculated. These can be influenced by the operator, for example to correct the elastic spring back. Based on the bending paths, the electronic cam disks for the individual axes are generated. The term "cam disk" is used here to refer to a clear assignment between a master drive and a slave drive. An electronic cam disk can, for example, be in the form of a support point table with position setpoints for the slave drive based on the time course, i.e. in the form of a path-time diagram for the slave drive.

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

An advantage of this approach is that the coupling of the bending path also allows process observation and control in setup mode (at a significantly reduced speed compared to production mode).

Preferably, the calculation is carried out 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 results between the bending tool and the wire and optimal force ratios are present in every phase of the bending operation. This allows optimized protection of the wire material even with large forces.

This path-controlled bending process can be used for numerous different chain link geometries within the working range of the chain bending machine with the same mechanical equipment of the chain bending machine. To change the format (i.e. a change to a different chain link geometry), only the bending mandrel and, if necessary, the bending rollers, i.e. only components that come into contact with the wire, need to be replaced. The other components of the bending unit, in particular the cam disks, do not need to be replaced. This reduces the number of possible replacement components to a minimum, so that assembly times, set-up times and adjustment times can be significantly reduced compared to conventional solutions. At the same time, there is a great deal of freedom with regard to the chain link shape, since the bending rollers can be guided on almost any path around the bending mandrel.

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

The examples show the processing of round wire, i.e. wire with a circular cross-section. In principle, wires with a different cross-section profile can also be processed, e.g. with a D-profile. For this purpose, some or all of the tools that come into contact with the workpiece may have to be designed accordingly.

To ensure sufficiently consistent quality and to avoid rejects, the chain bending machine 200 is equipped with a monitoring system for monitoring the operation of the chain bending machine and for detecting operational faults. The monitoring system makes it possible to detect impending problems in good time so that remedial action can be taken before minor defects in one of the functional units have a significant impact on the quality of the chain links. The monitoring system preferably includes a drive monitoring subsystem that can detect and display overload situations caused by faults. The drive monitoring subsystem is designed to record the time profiles of the motor torques of the individual machine drives of the machine axes. Using adjustable envelope curves, overloads of the machine and tools, caused for example by material breakage and/or tool breakage or by collision during setup, can be detected and prevented. The monitoring system can in particular be designed so that the operation of the system stops automatically if the drive monitoring subsystem has detected a significant overload problem. This indicates which drive caused the excessive machine torque that caused the shutdown, so that an operator can quickly determine the exact cause of the fault and eliminate it, for example by replacing a worn tool.

The monitoring system of the chain bending machine 200 also includes a subsystem for monitoring the notch depth of the notches produced by the notching device 940. Broken or worn notching blades can result in insufficiently deep notches, which subsequently cause problems with chain welding. Several meters of chain can be produced before this is noticed in the process, which is then considered scrap. With a subsystem for monitoring the notch depth, developing problems can be detected early at the source.

In the exemplary system of Fig. 1 For this purpose, an optical measurement of the notch point is provided using the camera 945. Alternatively or additionally, a system can also be provided to determine the force required when shearing the wire pin. A notch depth that is too small increases the required shearing force. Monitoring the motor torque for the machine axis that operates the shearing device 950 can therefore detect problems with insufficient Notch depth at the notching device 940. The shearing force can be determined at the shearing device 950, for example, via the required drive torque or via a separate force sensor.

A monitoring system for a chain bending machine can also be advantageous for other chain bending machines, regardless of the other features of the chain bending machine explained as an example, for example for those whose bending station is constructed differently than in the embodiment of Fig. 1 .

Claims (12)

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.

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