Computer-implemented method for adjusting the center of force or the shear force of a helical spring

Abstract

Computer-implemented method for adjusting a force center or a shear force of a helical spring (34) during cold winding with a cold winding machine (20) comprising the following steps: - Determining a geometry of the coil spring (34) during cold winding - Estimating, based on the determined geometry, a deviation of the force center or the shear force of the formed helical spring (34) using a set forming parameter of the cold wind machine (20) relative to a predetermined force center or shear force, - Adjusting the set forming parameter of the cold winding machine during the forming of the coil spring if the deviation is greater than a predefined threshold.

Description

[0001] The invention relates to the automatic adjustment of the force center, i.e. the lateral force, of a helical spring.

[0002] The cold-winding process for coil springs is generally subject to very high tolerances. Deviations from a specified spring geometry can, among other things, lead to a shift in the spring's center of force, causing it to generate an undesirable lateral force. This shift in the center of force can originate in the starting material, the spring wire, or in the forming process, for example, due to wear on the winding tools. Tools include, in particular, deflection elements such as pulleys for adjusting the coil spring's diameter or pitch elements for adjusting the coil spring's pitch. The spring wire can exhibit variations in strength and thus an inhomogeneity in its shear modulus. This fluctuating shear modulus results in areas with different springback rates within a wire coil after the coil has been formed.

[0003] The shift in the center of force can be detected, for example, by the length of the spring, the measurement of the force penetration points, or by geometric variations such as the coil spacing, the (especially average) diameter of the helical spring, or the (especially average) pitch of the helical spring.

[0004] The points of force transmission can be checked on a measuring device, for example in Cartesian coordinates, and reflect the lateral forces of the spring. Lateral forces generated by a coil spring that deviate from the target values ​​have a negative impact on driving comfort and are largely responsible for shock absorber wear.

[0005] DE 603 ​​01 977 T2 discloses a device and a method for manufacturing a helical spring.

[0006] DE 601 07 301 T2 discloses a curved helical compression spring.

[0007] US 7 841 088 B2 discloses a method for manufacturing a coil spring.

[0008] DE 101 25 503 C1 discloses a wheel suspension.

[0009] The object of the present invention is therefore to create an improved concept for the cold winding of coil springs.

[0010] The problem is solved by the subject matter of the independent patent claims. Further advantageous embodiments are the subject matter of the dependent patent claims.

[0011] Exemplary embodiments show a computer-implemented method for setting the force center or lateral force of a helical spring during cold winding with an automatic cold winding machine. During cold winding, the spring wire used to manufacture the helical spring is typically already tempered and thus already possesses its final strength. The method first comprises determining the geometry of the helical spring during cold winding, preferably continuously or at predetermined points in the winding process. In determining the geometry, coil spacing and / or the (especially average) diameter of the helical spring and / or the (especially average) pitch of the helical spring can be ascertained. In particular, the profile of the diameter and / or the pitch of the helical spring can be determined.The geometry of the helical spring is determined, for example, using one or more lasers and / or a camera system.

[0012] After determining the geometry of the coil spring, a deviation of the force center or the transverse force of the (fully) formed coil spring from a predetermined force center or transverse force is estimated using a set forming parameter of the cold winding machine. In other words, during the forming process, an assessment is made as to whether the (fully) formed coil spring will have a force center or transverse force within a tolerance, or not.

[0013] If the deviation exceeds a predefined threshold, meaning the force center or lateral force lies outside a tolerance, the cold-winding machine's forming parameter is adjusted during the coil spring forming process. This adjustment allows the geometry of the formed coil spring to be modified so that the force center or lateral force lies below the threshold, i.e., within the tolerance.

[0014] The idea is therefore to reduce variations in shape caused by the manufacturing process (e.g., due to tool aging) by means of an automated process. Because of the uncontrollable fluctuations in material properties, it is all the more important that the shaping process has as little tolerance as possible.

[0015] In exemplary embodiments, the pitch of the end coil is set as a forming parameter. Adjusting the pitch of the end coil offers a simple way to correct the spring geometry at the very end of the forming process, in order to adjust the center of force or the lateral force. A further advantage is that at this point almost the entire coil spring is already wound, thus allowing for the best possible estimation of the deviation of the center of force from a predetermined center of force. The pitch of the coil spring can vary along its length and therefore does not need to be constant.

[0016] In further embodiments, the diameter of the helical spring is set as a shaping parameter. A coiling machine deforms the spring wire along two axes. One axis sets the spring pitch, the other controls the spring diameter. The force center of the helical spring can be set via either the spring diameter axis or the pitch axis. Adjusting the diameter of the helical spring thus represents a complement to, or an alternative to, adjusting the pitch of the coils. The diameter of the helical spring can vary along its length and therefore does not need to be constant.

[0017] In exemplary embodiments, the estimation of the deviation of the force center or the shear force of the formed helical spring from a predetermined force center or shear force is performed by an artificial intelligence using a set forming parameter of the cold coil forming machine. Utilizing the capabilities of artificial intelligence, a database can be populated with possible pitch and / or diameter values, which are correlated with the force point. The applicant, as a manufacturer of helical springs, has an enormous stock of springs whose properties were used for training and validating the artificial intelligence. If the cold coil forming machine is equipped with a suitable sensor, for example, a measuring laser, in particular one measuring laser per axis to be measured (pitch or diameter), the system can then determine the deviation of the force center or shear force.Equipped with a spring (diameter) or a camera system to continuously or at predetermined times record the diameter profile and pitch, particularly of the end coil, the artificial intelligence can detect fluctuations in the force point values ​​by adjusting the spring geometry along the diameter axis or by changing the pitch, especially of the end coil, and react directly based on an adapted geometry. This allows for control of the force center point or lateral forces. Any artificial intelligence model can be used that can estimate the force center point of helical springs during shaping using machine learning based on training data. Examples of such models include a neural network, a regression model, a slime mold algorithm, or a combination thereof.Other well-known models suitable for machine learning, and combinations thereof, can also be used.

[0018] Furthermore, a cold coiling machine for forming a helical spring is disclosed. The method described above can be carried out on this cold coiling machine as well as on any other cold coiling machine. The cold coiling machine includes a wire feed configured to introduce a wire into the machine for forming the helical spring. A first and a second deflection element are configured to set the current diameter of the helical spring as the first forming parameter. It is also possible to use a plurality of deflection elements with more than two deflection elements. A pitch element is configured to set the current pitch of the helical spring as the second forming parameter. For example, a deflection pulley can be used as the deflection element.Instead of the respective rollers, wedges or other suitable fixing elements can also be used, which form a fixed point for the wire running against the fixing element.

[0019] A sensor determines the geometry of the coil spring during the forming process and outputs corresponding sensor data. A signal processing unit is configured to estimate, based on the sensor data and using the set first and second forming parameters, any deviation of the force center or shear force of the formed coil spring from a predetermined force center or shear force. Furthermore, the unit adjusts the first and / or second forming parameters during the coil spring forming process if the deviation exceeds a predetermined threshold.

[0020] The wire feed allows the coil spring machine to work against the deflection element and the pitch element to form the coil spring. In other words, the wire feed guides the spring wire and pushes it against the essentially rigidly arranged deflection element and pitch element, thereby shaping the coil spring and its two axes.

[0021] Analogous to the procedure, a computer program is comprehensively disclosed with instructions which, when the program is executed by a computer, cause it to execute the procedure.

[0022] Preferred embodiments of the present invention are explained below with reference to the accompanying drawings. These show: Fig. 1: a schematic perspective representation of a cold wind automaton with which the above procedure can be carried out; Fig. 2: A schematic side view of three helical springs with different centers of force, which are in Fig. 2a, Fig. 2b and Fig. 2c are shown.

[0023] Before exemplary embodiments of the present invention are explained in detail below with reference to the drawings, it should be noted that identical, functionally equivalent or equivalent elements, objects and / or structures in the different figures are provided with the same reference numerals, so that the description of these elements shown in different exemplary embodiments is interchangeable or can be applied to one another.

[0024] Fig. Figure 1 shows a schematic perspective view of a cold winding machine 20. The cold winding machine 20 comprises two deflection elements 22a, 22b, shown here as deflection pulleys. It is also possible to use further deflection elements and thus any plurality of deflection elements. The deflection elements can be moved at least along an axis 22a', 22b', preferably three-dimensionally in space, to set a (current) diameter of the formed helical spring. The current position of the deflection elements 22a, 22b, i.e., the (current) diameter, can be referred to as the first forming parameter.

[0025] Furthermore, the cold winding mechanism 20 includes a pitch element 24. The pitch element 24 is freely positionable at least along an axis 24' to set the (current) pitch of the formed helical spring. For example, a working cylinder can be used as the pitch element. However, other configurations are also possible. The position of the pitch element, i.e., the (current) pitch, can be referred to as the second forming parameter.

[0026] The cold coiling machine 20 also includes a wire feed 26, symbolized by a directional arrow. The wire feed guides the wire 27 from the helical spring, either from a wire coil or already cut to the correct length, into the cold coiling machine for forming the helical spring. The feed allows the wire to work against the deflection element and the pitch element to form the helical spring. An example of the first turn 27' of the helical spring is shown. The speed of the wire feed can be described as the third forming parameter.

[0027] The cold coil forming unit 20 further comprises a sensor 28. The sensor 28 can determine the geometry of the coil spring during forming and output sensor data 30 corresponding to this geometry. The sensor data 30 can be processed by a signal processing unit 32. Based on the sensor data 30, the signal processing unit 32 can estimate a deviation of the force center or the shear force of the formed coil spring from a predetermined force center or shear force using the set first forming parameter and the set second forming parameter. Furthermore, the signal processing unit can adjust the first and / or the second forming parameter during the coil spring forming process if the deviation exceeds a predetermined threshold.

[0028] It should be noted again that the execution of the procedure is not limited to the cold wind machine shown here, but can also be carried out on other cold wind machines.

[0029] Fig. 2a, Fig. 2b and Fig. Figure 2c shows a schematic side view of three coil springs 34, each with different centers of force. The lines labeled F show the force line 36, and the dashed line 38 shows the central axis of the spring. L denotes the length of the spring, such that the spring rests against the vehicle, for example on spring plates, at its outer endpoints 40a and 40b. The intersection of the force line 36 with the endpoints 40a and 40b defines a force center 42a and 42b, respectively, of the coil spring 34. The lateral force of the spring 34 can be adjusted by varying the deviation of these two force centers 42a and 42b from the central axis 38. The lateral force of the spring 34 is specified, for example, by the customer.The described method now makes it possible to automatically compensate for deviations from a target geometry, based on knowledge of the spring geometry wound up to a measurement point (actual geometry), in order to set a predetermined force action line.

[0030] Fig. Figure 2a now shows an example of a force line 36, which runs parallel to the central axis 38 of the coil spring. Fig. Figure 2b shows an example of a force line 36 in which the force centers 42a, 42b are arranged symmetrically to the central axis 38 of the helix. Fig.Figure 2c shows an example of a force line 36, whose upper force center 42a lies on the central axis 38 of the coil spring and whose lower force center 42b is shifted to the left of the central axis 38. It should be noted that both the slope and the horizontal shift of the force line relative to the central axis of the spring are variable, and only three examples are shown here.

[0031] Although some aspects have been described in connection with a device, it is understood that these aspects also constitute a description of the corresponding process, so that a block or component of a device can also be understood as a corresponding process step or as a feature of a process step. Similarly, aspects described in connection with or as a process step also constitute a description of a corresponding block, detail, or feature of a corresponding device.

[0032] The embodiments described above merely illustrate the principles of the present invention. It is understood that modifications and variations of the arrangements and details described herein will be obvious to other people skilled in the art. Therefore, it is intended that the invention be limited only by the scope of protection set forth in the following claims and not by the specific details presented herein by way of description and explanation of the embodiments. Reference symbol list: 20 Cold Wind Automatic 22 Deflection element 24 slope element 26 Wire feed 27 wire 27' first turn of the coil spring 28 Sensor 30 sensor data 32 Signal processing unit 34 coil spring 36 Line of force action 38 Central axis 40 endpoints of the coil spring 42 centers of force

Claims

[1] Computer-implemented method for adjusting a force center or a shear force of a helical spring (34) during cold winding with a cold winding machine (20) comprising the following steps: - Determining a geometry of the coil spring (34) during cold winding - Estimating, based on the determined geometry, a deviation of the force center or the shear force of the formed helical spring (34) using a set forming parameter of the cold wind machine (20) relative to a predetermined force center or shear force, - Adjusting the set forming parameter of the cold winding machine during the forming of the coil spring if the deviation is greater than a predefined threshold. [2] Method according to claim 1, wherein in determining the geometry of the helical spring (34) a pitch of the helical spring, in particular a profile of the pitch of the helical spring (34), is determined. [3] Method according to one of the preceding claims, wherein in determining the geometry of the helical spring (34) a diameter of the helical spring (34), in particular a profile of the diameter of the helical spring (34), is determined. [4] Method according to one of the preceding claims, wherein the pitch of the end turn of the helical spring (34) is set as a shaping parameter. [5] Method according to one of the preceding claims, wherein the diameter of the helical spring (34) is set as a shaping parameter. [6] Method according to one of the preceding claims, wherein the estimation of the deviation of the force center or the transverse force of the formed helical spring (34) using a set forming parameter of the cold winder from a predetermined force center or a predetermined transverse force is performed by an artificial intelligence (32). [7] Cold winding machine (20) for shaping a coil spring (34) with the following features: - a wire feeder (26) configured to introduce a wire (27) into the cold winding machine (20) for shaping the coil spring (34); - a first and a second deflection element (22a, 22b) which are designed to set a current diameter of the helical spring (34) as a first shaping parameter; - a gradient element (24) which is designed to set a current gradient of the coil spring (34) as a second shaping parameter; - a sensor designed to determine a geometry of the helical spring (34) during the forming process and to output corresponding sensor data; - a signal processing unit which is configured to estimate, based on the sensor data, a deviation of the force center or the transverse force of the shaped helical spring (34) from a predetermined force center or transverse force using the set first shaping parameter and the set second shaping parameter; - Adjusting the first and / or the second forming parameter during the forming of the coil spring (34) if the deviation is greater than a predetermined threshold. [8] Cold winding machine according to claim 7, wherein the cold winding machine (20) is configured to work by means of the wire feed (26) against the deflecting element (22a, 22b) and / or the pitch element (24) to form the helical spring (24). [9] Computer program comprising instructions which, when the program is executed by a computer, cause it to execute the method according to claim 1.

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