EP3126073A1

EP3126073A1 - Method and spring winding machine for producing coil springs by spring winding

Info

Publication number: EP3126073A1
Application number: EP15711210.3A
Authority: EP
Inventors: Uwe-Peter Weigmann; Klaus Wurster; Andreas Sigg
Original assignee: Wafios AG
Current assignee: Wafios AG
Priority date: 2014-04-04
Filing date: 2015-03-23
Publication date: 2017-02-08
Anticipated expiration: 2035-03-23
Also published as: WO2015150130A1; DE102014206603B3; EP3126073B1

Abstract

The invention relates to a method for producing coil springs (F) by spring winding by means of a numerically controlled spring winding machine (100). In said method, a wire is fed by a feeding device (110) of a forming device (120) of the spring winding machine under the control of an NC control program and is formed into a coil spring by means of tools of the forming device, and a finished coil spring is then severed from the fed wire by means of a cutting device. At least one winding tool (122, 124) having a contact surface provided for contact with the fed wire is among the forming tools. Before spring production, the winding tool is adjusted in an adjustment operation. The method is characterized in that automatic referencing of a position of the winding tool is performed during the adjustment operation, at least one contact-surface position parameter that represents the position of the contact surface being determined and being automatically transmitted to the control device of the spring winding machine.

Description

Method and spring coiling machine for producing coil springs by spring winds

AREA OF APPLICATION AND PRIOR ART

The invention relates to a method for producing coil springs by spring winds by means of a numerically controlled spring coiling machine according to the preamble of claim 1 and to a suitable for performing the method spring coiling machine according to the preamble of claim 1 1st

Coil springs are machine elements that are required in numerous applications in large numbers and different designs. Coil springs, also referred to as twisted torsion springs, are usually made of spring wire and are designed as tension springs or compression springs depending on the load involved in use. Compression springs, in particular valve springs, clutch springs or suspension springs are needed, for example, in large quantities in the automotive industry.

Coil springs are nowadays commonly manufactured by spring winches using numerically controlled spring coiling machines. In this case, a wire (spring wire) is supplied under the control of an NC control program by means of a feeder a forming device of the spring coiling machine and formed by means of tools of the forming device to form a coil spring. The tools usually include one or more adjustable in terms of their position wind tools for establishing and possibly changing the diameter of spring coils. Occasionally, one or more pitch tools are provided to determine the local pitch of the spring coils at each stage of the manufacturing process. Upon completion of a forming operation, a finished coil spring is separated from the supplied wire under the control of the NC control program by means of a cutter.

In spring coiling machines, the wire to be coiled, usually through a fixed guide device, is conveyed against a specially shaped frontal contact surface of a first wind tool. Usually followed by a second Windewerkzeug, against the contact surface of the already pre-curved wire is pressed thereafter. The contact surface of a Windewerkzeugs usually has the shape of a groove which gives lateral guidance to the wire and is at the groove bottom in more or less small-surface pressure contact with the incoming wire. At the contact surface, the wire curves continuously and is thus converted into a helical spring. Winding tools have several degrees of freedom when installed in a spring coiling machine. In addition to the positioning of a wind tool in Cartesian space, ie with respect to the machine coordinate system, the rotation of the wind tools about their own axis and the tilting of the wind tools with respect to a reference direction are two further parameters which influence the parameters of the spring to be generated. The rotation is used, for example, in the spring winding machines described in DE 600 18 512 T2 in order to control the bias of the spring body. The tilt can also be used to control the bias of the spring body.

The correct setting of the wind tools when setting up the spring coiling machine for the manufacture of a new type of spring and / or after a tool change or re-sharpening a wind tool is a demanding task, which is usually afforded only by experienced operators in reasonable times. There are numerous approaches that pursue the goal of fast reproducible adjustment of wind tools on spring-winding machines.

For example, DE 37 01 088 A1 describes a winch device for spring-winding machines with interchangeable, presettable elements. It has wind pen holders and winch holders, which contain all the adjusting screws required for adjustments and adjustments. This can be carried out both in a suitable adjusting a presetting, as well as later in the machine readjustment. The device for presetting is designed so that the angular changes are taken on a measuring axis and displayed on an angle measuring device. For adjustment in the axial direction, a dial gauge is available. The adjustment made in the adjustment device can be transferred to the machine without falsification by the operator. The reproducibility not only simplifies and speeds up the basic setting, but also allows a change process with different brackets.

TASK AND SOLUTION

It is an object of the invention to further simplify the setting of wind tools on spring coiling machines. The aim is to enable fast setting of wind tools on spring-winding machines with high precision and reliably reproducible results. The adjustments should also be made for less experienced operators in a short time. To solve this problem, the invention proposes a method with the features of claim 1 and a spring coiling machine with the features of claim 1 1 before. Advantageous developments are specified in the dependent claims. The wording of all claims is incorporated herein by reference.

In the method, an automatic referencing of the position of the wind tool is performed during the setting operation. In this case, at least one contact surface position parameter, which represents the position of the contact surface of the wind tool, automatically, i. in particular without the intervention of an operator, transmitted to the control device of the spring coiling machine. Automatic referencing establishes, without intervention of an operator, a usable relationship between the machine coordinate system of the spring coiling machine and the position of the contact surface, so that the control of the spring coiling machine is known based on the referencing where and how the contact surface with respect to the machine coordinate system is positioned.

The controller may consider this information about the position of the contact surface in the sequence when performing the Federwindeoperation. By referencing the specific geometry of the wind tool of the control is made known without an operator must intervene. This method is suitable for any type of wind tools. For example, the windmill may have a windshield with a cylindrical shank, which can be inserted into a cylindrical bore of a Windestifthalters in a suitable axial position and optionally rotated about its longitudinal axis within the receiving bore. A wind finger may also have a shaft of polygonal cross-section, e.g. Rectangular cross section, have. The wind tool may also have a contact surface provided, a turntable-like wind insert, which can be attached to a winch insert holder in a defined position by means of screws or the like. Due to the many degrees of freedom of positioning a wind tool or the contact surface are in principle also many possibilities for errors that can lead to a misalignment and thus the production of rejects or bad parts. Automatic referencing systematically avoids such errors.

Some embodiments are characterized in that the wind tool, for which an automatic referencing is to be performed, in the automatic referencing by actuating at least one drive of a machine axis in a starting operation in a feed direction to a spring winding is delivered to a contact position in the one in advance defined initial contact with the spring coil is present, and that belonging to the contact position axis parameter of the machine axis or a thereof derived parameter is transmitted as a contact surface position parameter to the control unit of the spring coiling machine. This approach optimally utilizes the capabilities of some numerically controlled spring coiling machines and provides fast and accurate referencing capability.

The term "machine axis" generally refers to a movable device that can be moved by at least one drive, for example an electromechanical, electrohydraulic or electropneumatic drive, in at least one mechanical degree of freedom, which may be a translatory machine axis, for example a linearly movable one Or a rotary machine axis, for example a spindle, a machine axis can in principle either move a tool or the workpiece.

In the example, the machine axis is used for the infeed movement of the wind tool to be referenced. The axis position of this machine axis, which is present when the contact position is reached, can be stored and taken into account as tool zero point in subsequent operations. In particular, further delivery of the wind tool (after reaching the contact position) can be controlled as far as a desired position of the contact surface as a function of the contact surface position parameter determined in the starting operation.

There are different ways to reliably determine the achievement of the defined initial contact.

In one variant, a feed force of the drive of the machine axis responsible for the feed movement is limited to a limit value, which is designed such that the drive stops when the defined initial contact is reached for performing the starting operation. In this case, it is utilized that the counterforce generated by the spring turn applied or the mechanical resistance which this spring turn counteracts the delivered wind tool is sufficient to end the axial feed. The mentioned limit value can be set, for example, by limiting the motor torque of the drive or the current consumption of the drive directly correlated with the motor torque to a suitably low value. For this purpose, possibly existing facilities modern drive systems can be exploited by tapping a torque torque signal proportional to the torque and processed for the starting operation. A force-controlled delivery during automatic homing would also be possible by providing a force sensor coupled to the wind tool whose display is monitored and evaluated to register the initial contact.

According to another approach, which may be provided alternatively or additionally, it is provided in some embodiments that the reaching of the contact position is detected optically by means of an optical detection device. The achievement of the contact position can thus be determined contactlessly from a suitable distance. As an optical detection device, for example, a laser or a camera (line camera or area camera) can be used.

However, when setting up wind tools on spring coiling machines, there are particular problems in reliably detecting the contact between the spring coil and the wind tool, in that the relevant contact surface of the wind tool is generally designed as a groove curved in its longitudinal direction with a more or less semicircular cross-section in order, on the one hand, to dislodge to cause the zugeförderten wire in the groove longitudinal direction and on the other hand to give the wire a lateral guidance. The more or less small-area contact zone between the wire and groove bottom is not readily visible from the outside, especially since it is concealed laterally by the groove walls.

In one variant, the special features of spring winding machines are taken into account by detecting the reaching of the contact position by means of a motion sensor which detects a movement of the spring section coming into contact with the contact surface of the wind tool. This is in relative calm as long as the wind tool has not yet set. Only when a secure contact, i. a defined initial contact, between the contact surface and spring coil is made, with the forces on the spring coil can be transmitted, makes the contact on further delivery of the Windewerkzeugs as movement of the contacted spring portion noticeable. This movement then indicates reaching the contact position. By means of a motion sensor, therefore, an indirect detection of reaching the contact position is possible.

In one embodiment, this movement is detected by an obliquely or frontally directed to the wind situation camera to which an image processing system is connected. The camera acts as an optical motion sensor. Motion sensors operating according to other principles may also be provided, for example at least one inductive motion sensor, at least one capacitive motion sensor and / or a motion sensor with one or more lasers, which may be designed as point sensors or 2D sensors. The delivery of a wind tool is usually not finished when reaching the contact position. In some embodiments, the Windewerkzeug is delivered after reaching the contact position by another Zustellweg in delivery direction, the further feed path a predetermined amount of elastic spring deflection of a spring coil between a desired position of the spring coil in spring winds and a relaxed position of the spring coil in the absence of a created a wind tool corresponding spring coil squeezing side force.

For a particular spring type or a certain spring winding, the amount of elastic springing can be determined prior to the start of setting operations and a corresponding value in the control of the spring coiling machine already be deposited.

In some embodiments, the amount of elastic resilience after a previous spring wind operation is determined by determining a first position of a spring coil at a desired wind tool and then a second position of the spring coil after fully retracting the wind tool, for example, by a camera and the amount the elastic resilience is calculated from the difference between the first and the second position. The determination of the amount of elastic springing can, for example, take place immediately before the removal of a previously used, for example, worn, wind tool.

With such a method or such a measuring system, the elastic resilience of the wire used can be determined. It is thus also possible to automatically determine the characteristic curves which the machine uses to calculate out the elastic springback internally. As a result, the establishment of a new type of wire, wire diameter, new tools, etc. can be significantly simplified. In addition, when using a new coil, the quality of the wire could be checked so easily. The method or the measuring system for determining the elastic resilience may also be independent of the other features of the invention claimed herein, a self-protectable invention.

It is also possible to calculate the amount of elastic springing from corresponding spring data, such as wire diameter, modulus of elasticity of the wire material etc. by a FEM simulation or to determine otherwise, so that upstream metrological investigations can be omitted.

Another approach for an automatic referencing in some embodiments is that initially in a measuring operation on the wind tool a distance between When the contact surface and a defined reference point of the wind tool are measured, a reference dimension corresponding to the distance is recorded with reference to the measured wind tool in the sense of a tool identification that the reference point is positioned at a reference location of the tool holder when inserting the Windewerkzeugs in a tool holder of the spring coiling machine and that the contact surface position parameter is determined from the position of the reference location and the reference dimension.

The measuring operation is normally carried out outside the spring-reversing machine prior to installation of the corresponding winding tool. The measuring operation determines coordinates of the relevant zone of the contact surface in an auxiliary coordinate system of the measured wind tool. The reference point may e.g. be used as the zero point of this auxiliary coordinate system. When installing the measured or measured wind tool on the tool holder, a relationship between the auxiliary coordinate system of the wind tool and the machine coordinate system is then established by the wind tool or the reference point of the wind tool is positioned at a known with respect to its position in the machine coordinate system reference location of the tool holder. On the basis of the tool identification and the associated reference dimension, it is then possible for the controller to calculate the position of the contact surface in the machine coordinate system and then to control the wind tool further.

The reference dimension can be recorded for example in an information carrier of the wind tool and read out during installation and transmitted to the control unit of the spring coiling machine. For recording, for example, a bar code, a QR code or an RFID tag or a semiconductor memory which can be read out via a USB interface or another interface can be used. It is also possible to store a plurality of reference dimensions and associated tool identification data in a database accessible to the machine control and then retrieve the corresponding reference dimension when entering the tool identification from the memory and to take over in the control of the spring coiling machine.

The invention also relates to a spring coiling machine for producing helical springs by spring winds, which is configured to carry out the method described in this application and has corresponding components or devices.

Such a spring coiling machine can in particular have one or more devices for direct or indirect detection of the contact surface on the wind tool or of the contact between this contact surface and a spring coil. To the facilities can For example, a suitably oriented camera and / or a laser system and / or a capacitive or inductive measuring device belong. Occasionally, in principle suitable facilities on a spring coiling machine for other purposes already exist, for example, a camera for measuring the spring length and / or the spring diameter. This could be used with the appropriate orientation and evaluation of the image signals for the new purpose proposed here.

BRIEF DESCRIPTION OF THE DRAWINGS

Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. Showing:

Fig. 1 is a schematic overview of some structural elements of a CNC spring coiling machine according to an embodiment of the invention;

2 shows an enlarged detail of the area of the forming tools with two wind tools;

Fig. 3 is a perspective view of a wind finger illustrating degrees of freedom of positioning;

4 shows the adjustment of a wind finger according to the prior art (FIG. 4A) and according to an embodiment with measurement of the wind finger (FIG. 4B);

5 shows several phases of an embodiment of the automatic referencing by means of optical wire curvature recognition;

Fig. 6 several phases in the determination of the elastic resilience of a spring coil.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The schematic overview in Fig. 1 shows some structural elements of a CNC spring coiling machine 100 according to an embodiment of the invention. Fig. 2 shows an enlarged detail of the range of forming tools with two wind tools. The spring coiling machine 100 has a feeder 110 equipped with a plurality, eg three pairs of feed rollers 1 12, the successive wire sections of a wire 1 15 with a numerically controlled feed rate profile in the horizontal feed direction 1 17 coming into the area of a forming device 120 can supply. Some components of the forming devices can be clearly seen, for example, in FIG. The wire can be guided on the outlet side of the feed rollers by a wire guide device 1 16.

The wire is converted into a helical spring F by means of numerically controlled tools of the forming device 120. The tools include two offset by 90 ° wind tools, namely a first wind tool 122 and a second wind tool 124. The wind tools or their longitudinal axes are aligned in the radial direction to the central axis 1 18 and the position of the desired spring axis and provided for the diameter to determine the coil spring. The position of the wind tools with respect to the Cartesian machine coordinate system MKS with orthogonal axes x, y and z can be changed to default for the spring diameter when setting along oblique directions as well as in the horizontal direction to set up the machine for different spring diameters. A similar adjustment is also possible during the spring coil process to change the diameter as a function of the axial position of a turn along the spring. The movements can be made by means of electric drives under the control of numerical control. Details will be explained in connection with FIGS. 2 and 3. Other embodiments have only a single wind tool.

A pitch tool 130 has an effective surface oriented substantially perpendicular to the spring axis, which engages adjacent to the turns of the developing helical spring. The pitch tool can be moved parallel to the axis 1 18 of the developing helical spring (ie perpendicular to the plane of the drawing) by means of a numerically controlled adjusting drive of the corresponding machine axis. The advanced during manufacture of the spring wire is pushed by the pitch tool according to the position of the pitch tool in the direction parallel to the spring axis, wherein the position of the pitch tool, the local slope of the spring is determined in the appropriate section. Gradient changes are effected by axis-parallel process of the pitch tool during spring production. There are also variants without a separate pitch tool, in which the pitch is adjusted via the wind tools. The machine axes of the CNC machine belonging to the tools are controlled by a computer numerical control device 180, which contains memory devices in which the control software resides, which includes, inter alia, an NC control program for the working movements of the machine axes. In this application, the machine axes are identified by capital letters A, B, C,... Z and possibly numerals (eg Z1), while the axes of the machine coordinate system are denoted by lowercase letters x, y, z. The Z axis (machine axis) is usually not parallel to the z axis of the machine coordinate system.

FIG. 2 shows the situation in the area of the two wind tools 122, 124 in detail. The guided in the feed direction 1 17 through the wire guide 16 1 first strikes an inclined contact surface K1 of the first Windewerkzeugs 122 and is arcuately curved by the contact with this contact surface and pushed upward in the direction of the second Windewerkzeugs 124. At the contact surface K2 of the second Windewerkzeugs the developing spring coil is pushed aside again and takes the desired circular arc shape.

The contact surfaces K1, K2 are exactly like the contact surface K in Fig. 3 frontally mounted on the respective Windewerkzeug and have the shape of a longitudinally curved groove having a substantially C-shaped cross-section. A plane through the centerline of the groove bottom defines the groove plane. The supplied wire is curved substantially in the groove plane.

The position of each of the wind tools is variable in multiple directions by means of associated machine axes via the control of the spring coiling machine. A translatory Z1 axis extends in the longitudinal direction of the first wind tool 122 and serves for the radial feed in the direction of the spring coil to be influenced. The perpendicular X1 axis is parallel to the axis 1 18 of the machine coordinate system. To these two axes perpendicular to the Y1 axis extends in the transverse direction. Corresponding machine axes Z2 (radial infeed) and X2 and Y2 are provided for the second wind tool 124.

In order to illustrate the degrees of freedom in the adjustment of wind tools, Fig. 3 instead of the winch inserts of Fig. 1, a wind finger 300 with a cylindrical shaft 302, on the front end side, the groove-shaped contact surface K is formed. The wind finger can basically be positioned in Cartesian space at different positions. The wind finger can be delivered parallel to its longitudinal axis 304 by means of a Z-machine axis (feed axis). The twisting of the wind finger around its longitudinal axis (Angle of rotation α) and a tilt of the wind finger (tilt angle ß) are other parameters that influence the parameters of the spring to be generated.

The term "position of the wind tool" in this application is not limited to the position in the longitudinal direction of the wind tool (adjustable, for example, via the Z machine axis.) The rotational position (angle of rotation a) and the tilt position (angle of rotation Accordingly, a contact surface position parameter can not only contain information about the position along a linear feed direction, but alternatively or additionally also information about the rotational position and / or the tilt position.

A hitherto conventional technique in the setting of such a wind tool with Windefinger will be explained in connection with FIG. 4A. The wind finger was typically received in a cylindrical bore of a tool holder 310. The distance A of the frontal contact surface K to a reference surface REF1 on the tool holder was not defined. During installation, the operator could use tools such as vernier calipers or gauges to keep this distance A constant or properly adjusted. In operation, since the contact surface gradually wears due to fretting wear on contact with the passing wire during spring winding, this amount is reduced between the contact surface and the reference surface. To prevent the spring from becoming larger in diameter as a result of this wear, the winching tool was adjusted partly manually, partly with the aid of a camera measurement, by actuating the Z-machine axis. By adjusting the axis Z was thus compensated by the wear changing distance A. When installing a new wind finger, the position of the Z-axis had to be changed manually in order to avoid the production of too small a spring body, for example when using a not yet worn wind finger.

In one embodiment of the invention, such problems are avoided by an automatic referencing of the position of the contact surface K. In this case, it is achieved in a simple manner to process the axial position values of the Z machine axis provided for the delivery of the wind tool and a reference dimension in the control of the machine such that the operator no longer has to make any adjustment or adjustment when changing the wind finger (cf. 4B).

In this case, a wind finger is pre-measured before its installation. In the measuring operation or surveying operation, a reference dimension C between the contact surface K at the wind finger and a reference point REF2 at the wind finger is determined. The reference point can eg at the Contact surface lying opposite face of the Windefingers. The reference dimension C substantially corresponds to the distance of the contact surface to the reference point REF, measured at the lowest point of the curved groove parallel to the longitudinal axis of the wind finger. This value of the reference dimension C determined by measuring can be printed or coded as a numerical value, for example, as a bar code or QR code or electronically (USB, RFID) together with the wind finger and delivered. When installing a new, pre-measured wind finger can be dispensed by reading the reference dimension C on a manual device, when the tensioning system for the wind finger in the spring coiling the Windefinger positioned so that the reference point REF2 at Windefinger always at the same location, ie at the same reference location of the tool carrier 310, is positioned. For this purpose, in the example case, a mechanical stop 320 is provided on the tool carrier 310 or on the winch platform of the spring coiling machine. The position of the stop in the machine coordinate system is known, so that the position of the contact surface can be calculated using the reference dimension C in a wind finger sitting on the stop. A mechanical adjustment of the wind finger by an operator is therefore no longer necessary.

When the control of the spring coiling machine is informed of the reference dimension C by manual input by the operator or by semiautomatic or automatic transmission of corresponding data to the controller, it is possible, using the previously measured and therefore known values B and A, to adjust the wind finger used previously to determine the axis position Z of the machine axis, which positions the contact surface of the newly inserted wind finger exactly in the correct position Z ', which is then the zero point of the axis.

When producing a helical compression spring, the dimension C between the contact surface of the wind finger and the reference point on the wind finger is reduced by mechanical frictional wear. The spring coiling machine detects this usually in a production with a camera system over the diameter of the spring body, which gradually increases. The delivery of the wind finger over the Z axis is compensated by changing the Z position. When removing the Windefingers, for example, to replace the Windefinger against a not yet worn Windefinger, the current value of the Referenzmaßes C can be stored in a database, for example in a memory device of the control of the machine, or in a central database. When using an RFID chip, the current value C can also be stored on the RFID chip which is connected to the wind finger. If the used Windefinger used again, he will, for example identified by a bar code or a QR code. The last stored value A is then read from the database and processed for further control.

Alternatively, it is also possible for the last stored A value to be read out of an RFID chip attached to the wind finger or another information carrier. Thus, even when using already used Windefingern the spring coiling machine can be put into operation without mechanical adjustments by the operator are necessary.

In some embodiments, it is provided that the rotation of the wind finger and an optionally existing tilting of the wind finger are fixed. As a result, a simple change of Windefingers be favored without operator intervention even further. For this purpose, the construction may be selected such that the wind finger is always inserted into the machine in a value which is unambiguous with respect to the angle of rotation α. This can be realized for example by suitable stops. If these movements can not be performed by suitable machine axes, the position found for a helical compression spring can be indicated by a vernier, for example. In a new set up the spring coiling machine for the production of this spring, it is then sufficient to set the vernier back to the previously found and stored or otherwise recorded value.

It can therefore be achieved in a simple manner, when a change of a wind finger the reference dimension, which describes the distance of the contact surface to a reference dimension on the wind finger, to transfer the control of the spring coiling machine. The machine can then automatically correct the position of the Z-axis on the basis of this reference dimension and thus secures the exact positioning of the contact surface of the wind finger at its desired position. In addition to the x-y-z positioning of the contact surface in the coordinate system of the machine can be provided to store the tilting and / or rotation of the wind finger with a mechanical scale or as an axis movement. In this way, these angles or corresponding data can be transferred when switching to another type of spring, so that manual corrections may only be necessary as fine corrections.

Variants are also possible which allow automatic referencing of the position of the contact surface without prior measurement of a wind finger or another part of a wind tool. The following variants use the possibilities of modern spring-winding machines, which have a machine axis, with a wind tool in a defined feed movement in the direction of a spring winding under control the control unit can be defined defined. With the help of such a machine axis, the wind tool can be positioned accurately. However, the information required for an exact positioning, for example, after the removal of a wind tool or after changes in the total length of the Windewerkzeugs, for example, by re-grinding or adjusting the geometry in the front contact area, no longer exist.

In one embodiment, an automatic referencing system is provided, with the help of which even under these conditions a fast, accurate and repeatable tool positioning when setting up after a tool change or a new set up is possible. 1 and 2, a Z1 machine axis is provided for the infeed motion of the first wind tool 122 in the Z1 direction, and a Z2 machine axis is provided parallel to the Z2 feed direction for the feed movement of the second wind tool 124. The associated drives M1 and M2 of these machine axes are controlled by the control device 180.

First, the installation of a Windewerkzeugs on the spring winding machine. For example, a Windefinger can be used in a Windefingeraufnahme or a winch insert on a winch insert holder of the spring coiling machine and fixed in this recording. For example, the procedure for the first wind tool 122 in FIG. 2 is explained in greater detail here.

After installation of the tool, a starting operation is initiated by operating the associated drive M1 of the ZI machine axis, in which the wind tool is delivered in a feed direction (Z1 direction) to a spring winding FW. A special feature consists in the fact that for these starting operations, the engine torque of the first drive M1 or the current consumption correlating therewith is limited to a very low value by adaptation of input parameters. When the wind tool is moved over the Z1 axis in the direction of the wire or the center of the mandrel, the wind tool then reaches a contact position in which the front-side contact surface K1 of the wind tool hits the outside of the wire of the spring winding. When attempting to deliver further, the wire provides a force or resistance to the motor of the machine axis of the wind tool. This resistance causes a higher force or a higher torque or a higher current consumption of the drive motor M1 to realize the Achsverfahrwegs is required for a further delivery of the wind tool in the feed direction, ie for a further method of the associated Z1 machine axis. The setting of the limit value for the engine torque is now such that, with a certain low resistance, the permissible limit value for the current consumption or the torque of the axle is exceeded, so that the machine axis stops. This creates a defined initial contact. The axis parameter belonging to this contact position of the machine axis or a parameter derived therefrom is then adopted as the contact surface position parameter in the control of the spring winding machine, so that the automatic referencing is completed. Each further delivery of the wind tool via the Z1 machine axis to a desired position of the contact surface can then be controlled as a function of the contact surface position parameter.

An alternative embodiment of the realization of an automatic referencing will be described with reference to FIG. In this case, the wind tools are referenced via an optical wire curvature detection or via the detection of movements of touched wire sections or spring winding sections when delivering a wind tool. For this purpose, the associated embodiment of a spring coiling machine has a camera KAM shown only schematically in Fig. 2, which is directed in the manner of at least one spring coil, that any movements of the spring coil, which are associated with an increase or decrease in the radius of curvature, accurate and reliable quality and can be quantified. It can be a line camera or an area camera. The camera is aligned in the embodiment so that it is directed to the wind situation in the frontal, ie substantially parallel to the axis 1 18 of the spring winding machine in such a way that the wind tools facing half-turn FW and the two wire-contacting wind tools within the two-dimensional image field BF lie (see Fig. 5A or 6A).

FIGS. 5A, 5B describe the determination of the contact positions for the first wind tool 122 arranged at the bottom, with which the wire first comes into contact. FIGS. 5C and 5D show the determination of the contact positions for the upper second wind tool 124.

After installation and fixation of the wind tools on the corresponding tool holders, automatic starting operations for both wind tools are carried out one after the other. First, the lower first wind tool 122 moves in crawl, ie at low engine torque, towards the half-turn FW. The arrow CLOSED here indicates the infeed direction, which (for both wind tools) is less than 65 ° to the horizontal (wire feed direction). This feed direction can also be provided in the schematic example of FIG. 2. This movement is detected by the frontal half-turn camera KAM. As soon as the face-side contact surface K1 of the wind tool touches the wire and the wind tool is delivered slightly further, the half-turn is curved inwards (dashed lines). This movement is detected by the camera. At the first recognition a significant movement of the wire, a stop signal is transmitted to the controller. This stops the associated CNC machine axis and its position is saved.

After that, the CNC axis still advances by the amount of the elastic deflection AF of the half-turn and then stands in the exact position for the spring diameter to be twisted (FIG. 5B).

That part of the spring coil, which is located beyond the first wind tool 122 and passes in front of the second wind tool 124, is still mechanically relaxed in this situation. A corresponding starting operation is then carried out by actuation of the second drive M2 from the upper second winding tool 124. Again, the impact of the contact surface of the wind tool on the wire by an inward movement of the rest of the turn noticeable, which is detected by the camera (Fig. 5C). Once a movement is detected, the Z2 machine stops and its position is saved. Now, the Z2 machine axis still advances by the amount of elastic springing of the residual turn and then stands exactly in the intended for the spring-wind process target position (Fig. 5D). In this situation, the half-turn beyond the first wind tool 122 is also tensioned and the wire assumes a semicircular curvature.

The movement of the wire or the half-turn respectively at a measuring point MP directly at the end of the wire groove, i. at the exit end of the contact surface, measured, ie near the point at which the wire leaves the respective wind tool. It has been shown that in this way particularly precisely reproducible settings of the spring geometry are possible.

The amount of elastic springing, ie the Auffederweg is performed in this process variant before removing the old, previously used wind tools. The procedure will be explained with reference to FIG. 6. For this purpose, the position of the clamped half-turn is detected by the camera before removing the old wind tools. Then the CNC machine axis moves back with the associated wind tool until no more spring-back movement is detected by the camera. The differential travel AF between the target position of the wind tool when spring winds and that retracted position in which the winding section stretched by the returning wind tool is just fully relaxed, is stored as the amount of elastic springing in a memory of the controller. As shown in Fig. 6, the amount of elastic springing is determined separately for each wind tool as needed. In the situation in Fig. 6A, both wind tools are still in the inner target position and the half-turn FW is stretched circular arc. Fig. 6B shows the situation after retraction of the upper wind tool in the position in which the remaining winding is fully relaxed. The amount of elastic expansion is the difference in the position of the core of the wire in the fully tensioned state (dashed) and in the currently relaxed state measured in the feed direction (Z2 direction). In this situation, the winding beginning near the lower first wind tool 122 is still tense. Thereafter, a corresponding operation is performed with the lower wind tool by the lower wind tool withdrawn and the associated amount of elastic springing is determined in an analogous manner.

Some aspects of the invention have been explained using the example of the automatic referencing of those wind tools that substantially determine the diameter of the spring coils. Such wind tools can in some cases dictate the inclination and / or preload of a spring via the rotational position. The invention may also be used to refer to the position of a pitch tool that is separate from the diameter-targeting wind tools (e.g., pitch tool 130 in Figure 1). Such pitching tools used in spring winches are also to be understood as wind tools in the sense of this application. These can also be automatically positioned with the aid of corresponding automatic referencing.

Claims

claims

1 . A method for producing coil springs by spring-winding means of a numerically controlled spring coiling machine, wherein a wire under the control of an NC control program supplied by a feeder of a forming device of the spring coiling machine, converted by means of tools of the forming device into a coil spring and a finished coil spring then by means of a Cutting device is separated from the supplied wire,

wherein the forming tools comprise at least one winding tool with a contact surface provided for contact with the supplied wire, and the winding tool is set in a setting operation prior to spring manufacture,

characterized in that

during the setting operation, an automatic referencing of a position of the wind tool is performed, wherein at least one contact surface position parameter representing the position of the contact surface is determined and automatically transmitted to the control device of the spring coiling machine.

2. The method according to claim 1, characterized in that the wind tool is delivered in the automatic referencing by operating at least one drive of a machine axis in a starting operation in a delivery direction on a spring winding to a contact position in which there is a predefined initial contact with the spring coil and in that an axis parameter belonging to the contact position of the machine axis or a parameter derived therefrom is transmitted as the contact surface position parameter to the control unit of the spring coiling machine.

3. The method according to claim 2, characterized in that a further delivery of the Windewerkzeugs is controlled to a desired position of the contact surface in dependence on the contact surface position parameter.

4. The method of claim 2 or 3, characterized in that for performing the starting operation, a delivery force of the drive is limited to a limit, which is designed such that the drive stops when the defined initial contact is reached, preferably a limit for the Motor torque and / or the current consumption of the drive is adjusted so that at a given resistance of the spring coil of the set limit is exceeded, so that the machine axis stops, whereby a defined initial contact is made.

5. The method according to any one of the preceding claims, characterized in that the achievement of the contact position by means of an optical detection means is optically detected.

6. The method according to any one of the preceding claims, characterized in that the reaching of the contact position by means of a motion sensor, in particular a camera, is detected, which detects a movement of a passing with the contact surface of the Windewerkzeugs in contact spring portion.

7. The method according to any one of the preceding claims, characterized in that the wind tool is delivered after reaching the contact position to another feed in the feed direction, wherein the further feed path an amount of elastic spring deflection of a spring between a desired position of the spring coil in spring winds and a relaxed position the spring coil in the absence of generated by a wind tool, the spring coil squeezing side force corresponds.

8. The method according to claim 7, characterized in that the amount of elastic springing after a previous Federwindeoperation is determined by determining a first position of a spring winding at a standing in desired position Windewerkzeug and a second position of the spring coil after retraction of the Windewerkzeugs and the amount of elastic springing is calculated from a difference of the first and the second position.

9. Method according to one of the preceding claims, characterized in that a distance between the contact surface and a defined reference point of the wind tool is measured on the wind tool in a surveying operation upstream of the installation on the spring winding machine,

recording a reference dimension corresponding to the distance with reference to the measured wind tool,

upon insertion of the wind tool into a tool holder of the spring coiling machine, the reference point is positioned at a reference location of the tool holder and the contact surface position parameter is determined from the position of the reference location and the reference dimension.

10. The method according to claim 9, characterized in that the reference dimension is recorded in an information carrier of the Windewerkzeugs.

1 1. Spring winding machine (100) for the production of coil springs (F) by spring winds comprising:

a feed device (1 10) for feeding wire (1 15) to a forming device (120) which has at least one wind tool (122, 124) which comprises a contact surface (K, K1, K2) provided for contact with the supplied wire wherein the wind tool is adjustable before spring manufacture in a setting operation, and

a control device (180) for controlling the feed device and the shaping device on the basis of an NC control program,

marked by,

a referencing system for automatic referencing of the position of the wind tool, wherein the referencing system is configured such that during the adjustment operation at least one contact surface position parameter representing the position of the contact surface can be determined and automatically transferred to the control device (180) of the spring coiling machine.

12. Spring coiling machine according to claim 1 1, characterized in that the spring coiling machine (100) for performing the method according to one of claims 1 to 10 is configured.