A pressure control method for a multi-station positioning fixture for welding composite brake drums

Abstract

This invention relates to the field of workpiece welding and fixing, specifically to a pressure control method for a multi-station positioning fixture used in welding composite brake drums. The method first determines the potential for offset of each fixture at the current moment based on the distribution of pressure data for each fixture over a preset time period prior to the current moment, and the difference in pressure data between fixtures holding the same type of workpiece at the current moment. Then, by combining the differences between the distance from the welding position to each fixture at the current moment and the distance from each fixture to the center of the target workpiece, the clamping offset interference degree of each fixture at the current moment is obtained. Based on the difference in clamping offset interference degree between the two closest fixtures holding different workpieces at the current moment, the clamping imbalance degree of the fixture at the current moment is obtained, and the clamping pressure of the fixture at the next moment is controlled. This invention can effectively control the clamping pressure of each fixture, avoiding fixture position offset during welding and improving the clamping effect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of workpiece welding fixing, in particular to a multi-station positioning clamp pressure control method for composite brake drum welding. BACKGROUND

[0002] The composite brake drum is a key component for automobile braking system composed of two or more different materials through welding. In the manufacturing process of the composite brake drum, the welding process between different workpieces (such as friction rings and flange plates) is the core technology. Usually, different workpieces are fixed by mechanical clamps, and the workpieces are welded by a welding gun. In the welding process, improper control of the clamping pressure of the mechanical clamp will reduce the welding effect. Therefore, it is of great significance to control the clamping pressure of the mechanical clamp.

[0003] In related technologies, the different components of the composite brake drum are clamped and fixed by mechanical clamps, and then the annular gap is welded by a fixed-angle welding gun. The mechanical clamp rotates the position through the connected rotary positioner to make the welding gun continue to weld the remaining gaps between the workpieces. However, in actual situations, when welding different workpieces, a large amount of vibration is generated and transmitted to the workpieces, causing the workpieces to vibrate, resulting in a certain deviation of the clamps with insufficient pressure, and reducing the clamping effect of the clamps. SUMMARY

[0004] In order to solve the technical problem that the vibration generated in the welding process will cause a certain deviation of the clamps with insufficient pressure, and reduce the clamping effect of the clamps, the purpose of the present application is to provide a multi-station positioning clamp pressure control method for composite brake drum welding, and the technical solution adopted is as follows:

[0005] The present application provides a multi-station positioning clamp pressure control method for composite brake drum welding, which comprises:

[0006] In the process of welding two workpieces of the composite brake drum, the pressure data applied by each clamp of the different workpieces is acquired in real time;

[0007] The composite brake drum is any one workpiece as a target workpiece, and any one clamp clamping the target workpiece is taken as a target clamp. The offset possibility of the target clamp at the current time is obtained according to the distribution of pressure data of the target clamp at each time within a preset time period before the current time, and the difference between the pressure data of the target clamp and other clamps clamping the target workpiece except the target clamp at the current time. The clamping offset dominance of the target clamp at the current time is obtained according to the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the center of the target workpiece. The clamping offset interference degree of the target clamp at the current time is obtained according to the offset possibility of the target clamp at the current time and the clamping offset dominance of each clamp clamping the target workpiece at the current time.

[0008] Another workpiece is taken as a reference workpiece, and the clamp clamping the reference workpiece closest to the target clamp is taken as the reference clamp of the target clamp. The clamping imbalance degree of the target clamp at the current time is obtained according to the difference between the clamping offset interference degrees of the target clamp and the reference clamp at the current time.

[0009] The clamping pressure of the target clamp at the next time is controlled based on the clamping imbalance degree.

[0010] Further, the offset possibility of the target clamp at the current time comprises:

[0011] The average value of the absolute value of the difference between the pressure data of all other clamps clamping the target workpiece except the target clamp and the target clamp at the current time is taken as the pressure difference characteristic value of the target clamp at the current time.

[0012] The offset coefficient of the target clamp at the current time is obtained according to the difference between the pressure difference characteristic values of the target clamp and other clamps clamping the target workpiece except the target clamp at the current time.

[0013] The vibration interference degree of the target clamp at the current time is obtained by analyzing the dispersion degree of the pressure data of the target clamp at all times within a preset time period before the current time.

[0014] The offset possibility of the target clamp at the current time is obtained by synthesizing and normalizing the vibration interference degree and the offset coefficient.

[0015] Further, the offset coefficient of the target clamp at the current time comprises:

[0016] The average value of the absolute value of the difference between the pressure difference characteristic values of all other clamps clamping the target workpiece except the target clamp and the target clamp at the current time is taken as the offset coefficient of the target clamp at the current time.

[0017] Further, the obtaining of the clamping offset interference degree of the target clamp at the current time comprises:

[0018] If the distance from the welding position at the current time to the target clamp is less than the distance from the target clamp to the target workpiece circle center, then the absolute value of the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the target workpiece circle center is taken as the numerator, the distance from the target clamp to the target workpiece circle center is taken as the denominator, and the ratio is negatively normalized to obtain the clamping offset dominance of the target clamp at the current time.

[0019] If the distance from the welding position at the current time to the target clamp is not less than the distance from the target clamp to the target workpiece circle center, then the absolute value of the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the target workpiece circle center is taken as the numerator, the distance from the welding position at the current time to the target clamp is taken as the denominator, and the ratio is normalized to obtain the clamping offset dominance of the target clamp at the current time.

[0020] Further, the obtaining of the clamping offset interference degree of the target clamp at the current time comprises:

[0021] Based on the clamping offset dominance of each clamp clamping the target workpiece at the current time, the clamps clamping the target workpiece at the current time are screened out as the rotation offset clamps.

[0022] According to the distance between each of the rotation offset clamps at the current time and the number of rotation offset clamps, the rotation influence degree at the current time is obtained.

[0023] According to the rotation influence degree at the current time, the clamping offset dominance of the target clamp at the current time is adjusted, and combined with the offset possibility of the target clamp at the current time, the clamping offset interference degree of the target clamp at the current time is obtained.

[0024] Further, the screening out of the rotation offset clamps at the current time from all clamps clamping the target workpiece comprises:

[0025] Among all clamps clamping the target workpiece, the clamps with the clamping offset dominance less than a preset offset threshold are taken as the rotation offset clamps at the current time.

[0026] Further, the obtaining of the rotation influence degree at the current time comprises:

[0027] The average value of the distance between all arbitrary two rotation offset clamps at the current time is taken as the rotation influence factor at the current time.

[0028] The rotation influence factor at the current moment and the number of rotation offset clamps are integrated and normalized to obtain the rotation influence degree at the current moment.

[0029] Further, the holding offset dominance of the target clamp at the current moment is adjusted according to the rotation influence degree at the current moment, and the holding offset interference degree of the target clamp at the current moment is obtained by combining the offset possibility of the target clamp at the current moment, which comprises:

[0030] The product value of the rotation influence degree at the current moment and the holding offset dominance of the target clamp at the current moment is taken as the holding offset adjustment amount of the target clamp at the current moment.

[0031] The difference value between the holding offset dominance of the target clamp at the current moment and the holding offset adjustment amount is taken as the adjusted holding offset dominance of the target clamp at the current moment.

[0032] The adjusted holding offset dominance of the target clamp at the current moment and the offset possibility are integrated and normalized to obtain the holding offset interference degree of the target clamp at the current moment.

[0033] Further, the holding imbalance degree of the target clamp at the current moment comprises:

[0034] The absolute value of the difference between the holding offset interference degrees of the target clamp and the reference clamp at the current moment is normalized to obtain the holding imbalance degree of the target clamp at the current moment.

[0035] Further, the holding pressure of the target clamp at the next moment is controlled based on the holding imbalance degree, which comprises:

[0036] The product value of the holding imbalance degree of the target clamp at the current moment and the pressure data is taken as the holding pressure adjustment amount of the target clamp at the current moment.

[0037] The sum value of the pressure data of the target clamp at the current moment and the holding pressure adjustment amount is taken as the holding pressure of the target clamp at the next moment.

[0038] The present application has the following advantages:

[0039] The present application considers that the vibration generated in the welding process can cause a certain deviation of the clamp with insufficient pressure application, and reduces the clamping effect of the clamp, so first, the pressure data applied by each clamp of different workpieces is acquired in real time, considering that the vibration generated in the welding process can cause a large fluctuation of the pressure applied by the clamp, and the pressure applied by each clamp at the same time is quite different, so the possibility of deviation of the target clamp due to welding vibration can be preliminarily reflected by the acquired deviation possibility, considering that the workpiece welding of the composite brake drum is a rotating process, and the centrifugal force generated by rotation can also cause the position of the clamp to deviate, so it will be mistakenly believed that the deviation of the clamp is caused by improper clamping of the clamp, so the relevance of the target clamp due to the clamping deviation caused by the clamping condition of the target clamp is reflected by the acquired clamping deviation dominance, and then the possibility that the target clamp is caused by improper clamping during the welding process is reflected by the acquired clamping deviation interference degree, so as to eliminate the influence of the centrifugal force of rotation, and considering that the materials of different workpieces are different, the response degree of different workpieces to welding vibration is different, and then different workpieces produce different deviation conditions due to welding vibration, so by analyzing the difference between the clamping deviation interference degree of the target clamp and the reference clamp at the current time, and by acquiring the clamping imbalance degree, the clamping pressure of the target clamp at the next time is controlled, so that the clamp can clamp the workpiece more stably during welding, and the clamping effect of the clamp is improved. BRIEF DESCRIPTION OF DRAWINGS

[0040] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, and the advantages thereof, the following will briefly introduce the drawings needed in the embodiments or prior art description. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can also be obtained without creative labor.

[0041] Figure 1 A flow chart of a multi-station positioning clamp pressure control method for composite brake drum welding is provided for an embodiment of the present application. DETAILED DESCRIPTION

[0042] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined invention purpose, the following will combine the drawings and the preferred embodiments to specifically describe a multi-station positioning clamp pressure control method for composite brake drum welding according to the present application, its specific implementation, structure, features and effects, which are described in detail as follows. In the following description, different "one embodiment" or "another embodiment" do not necessarily refer to the same embodiment. In addition, the specific features, structures or characteristics in one or more embodiments can be combined in any suitable form.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0044] The specific scheme of the pressure control method of the multi-station positioning clamp for welding of a composite brake drum is specifically described below in combination with the drawings.

[0045] Referring to Figure 1 , a flow chart of the pressure control method of the multi-station positioning clamp for welding of a composite brake drum is shown, and the method comprises:

[0046] Step S1: In the process of welding two kinds of workpieces of the composite brake drum, real-time acquisition of the pressure data applied by each clamp to different workpieces is performed.

[0047] In the process of welding different workpieces (such as a friction ring and a flange plate) of the composite brake drum, since welding will produce a relatively obvious vibration phenomenon, for a certain workpiece, a plurality of mechanical clamps are usually used to clamp the workpiece, so that the workpiece is kept stable during welding, to avoid a relatively large displacement due to vibration and reduce the final welding effect. At the same time, since the angle of the welding torch is fixed during welding, the mechanical clamps need to be connected to a rotary positioner, and the workpieces clamped by the clamps are welded to each other by means of rotary welding.

[0048] Since a relatively obvious vibration phenomenon will occur during welding, in order to ensure the stability of the workpieces and the clamps during welding, the clamping pressure of each clamp needs to be strictly controlled. Therefore, in the process of welding two kinds of workpieces of the composite brake drum, an embodiment of the present application takes the two kinds of workpieces of the friction ring and the flange plate as examples. First, a pressure sensor is installed between each clamp and the workpiece, and the pressure sensor is used to collect the pressure data applied by each clamp to different workpieces in real time.

[0049] Step S2: Any kind of workpiece of the composite brake drum is taken as a target workpiece, any one of the clamps clamping the target workpiece is taken as a target clamp, the offset possibility of the target clamp at the current time is obtained according to the distribution of the pressure data of the target clamp at each time within a preset time period before the current time, and the difference between the pressure data of the target clamp and other clamps clamping the target workpiece at the current time, the clamping offset dominance of the target clamp at the current time is obtained according to the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the center of the target workpiece, and the clamping offset interference degree of the target clamp at the current time is obtained according to the offset possibility of the target clamp at the current time and the clamping offset dominance of each clamp clamping the target workpiece at the current time.

[0050] For a plurality of clamps on a workpiece, since the clamps are distributed at different positions on the workpiece, the vibration generated during the welding process will have different effects on different clamps on each workpiece, so it is necessary to analyze the single clamp, the embodiment of the application first takes any one workpiece of the composite brake drum as the target workpiece, and takes any one clamp clamping the target workpiece as the target clamp, since the vibration phenomenon generated during the welding process will cause the pressure applied by the clamp to fluctuate greatly, and the pressure applied by each clamp at the same time is greatly different, therefore, the distribution of the pressure data of the target clamp at each time within a preset time period before the current time, and the difference between the pressure data of the target clamp and other clamps clamping the target workpiece except the target clamp at the current time can be analyzed, and the offset possibility of the target clamp due to welding vibration can be preliminarily reflected by the obtained offset possibility, wherein the length of the preset time period is in the range of [10, 30], in an embodiment of the application, the length of the preset time period is set to 20, that is, the preset time period contains 20 time points before the current time, the length of the preset time period can also be set by the implementer according to the specific implementation scene, which is not limited here, and it should be noted that when analyzing the current time, a time period with sufficient length before the current time is needed to ensure that the preset time period before the current time can be analyzed.

[0051] Preferably, in an embodiment of the application, the method for obtaining the offset possibility of the target clamp at the current time specifically includes:

[0052] Firstly, the average value of the absolute value of the difference between the pressure data of all other clamps clamping the target workpiece except the target clamp and the target clamp at the current time is taken as the pressure difference characteristic value of the target clamp at the current time, the greater the pressure difference characteristic value, the greater the difference between the clamping pressure of the target clamp and all other clamps clamping the target workpiece at the current time.

[0053] As an example, in an embodiment of the application, the expression of the pressure difference characteristic value of the target clamp at the current time can be specifically for example:

[0054]

[0055] Wherein, ΔF represents the pressure difference characteristic value of the target clamp at the current time; F represents the pressure data of the target clamp at the current time; F i represents the pressure data of the i-th other clamp clamping the target workpiece except the target clamp at the current time; I represents the number of all other clamps clamping the target workpiece except the target clamp.

[0056] The pressure difference characteristic value of each clamp clamping the target workpiece at the current time can be obtained by the same method as above. The greater the difference between the pressure difference characteristic value of the target clamp at the current time and the pressure difference characteristic value of other clamps clamping the target workpiece at the current time, the more likely the position of the target clamp is the main direction of vibration propagation, and the greater the possibility of the target clamp being affected by the welding vibration and appearing position deviation. Therefore, the deviation coefficient of the target clamp at the current time can be obtained according to the difference between the pressure difference characteristic value of the target clamp at the current time and the pressure difference characteristic value of other clamps clamping the target workpiece at the current time, and the deviation possibility of the target clamp at the current time can be accurately calculated based on the deviation coefficient.

[0057] Preferably, in an embodiment of the present application, the method for obtaining the deviation coefficient of the target clamp at the current time specifically comprises:

[0058] The average value of the absolute value of the difference between the pressure difference characteristic value of the target clamp at the current time and the pressure difference characteristic value of all other clamps clamping the target workpiece at the current time is taken as the deviation coefficient of the target clamp at the current time.

[0059] As an example, in an embodiment of the present application, the expression of the deviation coefficient of the target clamp at the current time can be specifically, for example:

[0060]

[0061] Wherein, A represents the deviation coefficient of the target clamp at the current time; ΔF represents the pressure difference characteristic value of the target clamp at the current time; ΔF i represents the pressure difference characteristic value of the i-th other clamp clamping the target workpiece at the current time, except for the target clamp; and I represents the number of all other clamps clamping the target workpiece, except for the target clamp.

[0062] Then, the more obvious the fluctuation of the pressure data of the target clamp in the preset time period before the current time in time sequence, the more likely the target clamp is continuously affected by the vibration, and the greater the possibility of the target clamp being affected by the welding vibration and appearing position deviation. Therefore, the dispersion degree of the pressure data of the target clamp at all times in the preset time period before the current time can be analyzed to obtain the vibration interference degree of the target clamp at the current time.

[0063] In an embodiment of the present application, the standard deviation, variance or range of the pressure data of the target clamp at all times in the preset time period before the current time can be taken as the vibration interference degree of the target clamp at the current time, to realize the analysis of the dispersion degree of the pressure data of the target clamp at all times in the preset time period before the current time, which is not limited herein.

[0064] Further, the vibration interference degree and the offset coefficient are synthesized and normalized to limit the calculation result in the range of [0, 1], so as to obtain the offset possibility of the target clamp at the current time.

[0065] In the embodiments of the present application, the synthesis of the vibration interference degree and the offset coefficient of the target clamp at the current time can be realized by calculating the sum or product value of the two, which is not limited herein, and the synthesis of two or more data in the subsequent steps can also be realized by using the same method.

[0066] In the embodiments of the present application, the normalization processing can be realized by using an activation function or a hyperbolic tangent function, which will not be described and limited herein, and the normalization processing in the subsequent steps can also be realized by using the same method.

[0067] As an example, in an embodiment of the present application, the expression of the offset possibility of the target clamp at the current time can be specifically, for example:

[0068] C=tanh(A x σ)

[0069] Wherein, C represents the offset possibility of the target clamp at the current time; A represents the offset coefficient of the target clamp at the current time; σ represents the standard deviation of the pressure data of all times in the preset time period before the current time of the target clamp, i.e. the vibration interference degree of the target clamp at the current time; tanh() represents a hyperbolic tangent function for normalization processing.

[0070] In the actual welding process, the area being welded as the vibration occurrence point, the vibration generated thereby will spread to both sides of the workpiece respectively, at this time, the position where the vibration is generated is the position of the workpiece being welded, and the vibration generated thereby spreads along the workpiece to the position clamped by the clamp, when the vibration spreads from one end to the other end, the swing amplitude generated at the clamp position will also increase with the increase of the distance between the welding position and the clamp position, at the same time, since the welding is a process of rotating while welding, and the workpiece rotates together with the clamp, the centrifugal force generated in the rotating process can also cause the offset of the clamp position, so that it is mistakenly considered that the offset of the clamp is caused by improper clamping of the clamp, and the degree of action of the centrifugal force generated by rotation on the clamp depends on the distance between the clamp and the center of the workpiece, therefore, the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the center of the target workpiece can be analyzed, the correlation of the clamping offset dominance reflecting the phenomenon that the target clamp appears clamping offset due to its own clamping condition is obtained, the greater the clamping offset dominance, the more likely the offset of the target clamp is caused by improper clamping of the target clamp under the premise of welding vibration, and the less likely the offset of the target clamp is caused by the centrifugal force generated by rotation.

[0071] Preferably, in one embodiment of the present application, the method for obtaining the dominance of the clamping deviation of the target clamp at the current time specifically comprises:

[0072] If the distance from the welding position at the current time to the target clamp is less than the distance from the target clamp to the center of the target workpiece, it indicates that the influence of the welding vibration is lower than that of the rotational centrifugal force at the current time. The greater the difference between the two distances, the more likely the deviation of the target clamp is caused by the rotational centrifugal force, and the lower the relevance of the target clamp to the clamping deviation phenomenon caused by its own clamping condition. Therefore, the absolute value of the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the center of the target workpiece can be used as the numerator, the distance from the target clamp to the center of the target workpiece as the denominator, and the correlation between the two values is negatively normalized to limit the calculation result within the range of [0, 1], thereby obtaining the dominance of the clamping deviation of the target clamp at the current time.

[0073] If the distance from the welding position at the current time to the target clamp is not less than the distance from the target clamp to the center of the target workpiece, it indicates that the influence of the welding vibration is higher than that of the rotational centrifugal force at the current time. The greater the difference between the two distances, the more likely the deviation of the target clamp is caused by the welding vibration, and the higher the relevance of the target clamp to the clamping deviation phenomenon caused by its own clamping condition. Therefore, the absolute value of the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the center of the target workpiece can be used as the numerator, the distance from the welding position at the current time to the target clamp as the denominator, and the correlation between the two values is normalized to limit the calculation result within the range of [0, 1], thereby obtaining the dominance of the clamping deviation of the target clamp at the current time.

[0074] As an example, in one embodiment of the present application, the expression of the dominance of the clamping deviation of the target clamp at the current time can be specifically as follows:

[0075]

[0076] Wherein, E represents the dominance of the clamping deviation of the target clamp at the current time; D represents the distance from the welding position at the current time to the target clamp; D ′ represents the distance from the target clamp to the center of the target workpiece; tanh() represents the hyperbolic tangent function for normalization processing, and 1-tanh() is used for negative correlation normalization processing.

[0077] The dominance of the clamping deviation of each clamp clamping the target workpiece at the current time can be obtained by the same method as described above.

[0078] When the workpiece held by the clamp deviates, two vibration tracks are mainly formed, one is that the vibration direction is unidirectional, at this time, the vibration return point of the workpiece is more likely to pass through the center of the brake drum, and when the clamp rotates, it still passes through the center of the brake drum, only the vibration direction changes with the rotation direction of the clamp, so the influence of the centrifugal force generated by rotation on the vibration pair is smaller, and the influence of the centrifugal force generated by rotation is smaller, and the other is that the vibration return point does not pass through the center of the brake drum, and the more irregular, in the vibration condition, even a small centrifugal force is easy to cause the clamp to hold loose, therefore, according to the deviation possibility of the target clamp at the current time, and combining the holding deviation dominance of each clamp holding the target workpiece at the current time, the holding deviation interference degree of the target clamp at the current time is obtained, the possibility that the target clamp deviates due to improper holding is reflected by the holding deviation interference degree in the welding process, so as to eliminate the influence of the centrifugal force of rotation, and improve the control accuracy of the holding pressure of the target clamp subsequently.

[0079] Preferably, in an embodiment of the present application, the method for obtaining the holding deviation interference degree of the target clamp at the current time specifically comprises:

[0080] Firstly, the smaller the holding deviation dominance of a certain clamp holding the target workpiece at the current time, the more likely it is that the loosening deviation phenomenon of the clamp at the current time is caused by the centrifugal force generated by rotation, so the rotating deviation clamp at the current time can be selected from all the clamps holding the target workpiece based on the holding deviation dominance of each clamp holding the target workpiece at the current time.

[0081] Preferably, in an embodiment of the present application, among all the clamps holding the target workpiece, the clamps with a holding deviation dominance less than a preset deviation threshold value can be taken as the rotating deviation clamps at the current time, wherein the preset deviation threshold value is in the range of (0, 1), in an embodiment of the present application, the preset deviation threshold value is set to 0.5, and the specific value of the preset deviation threshold value can also be set by the implementer according to the specific implementation scene, which is not limited here.

[0082] Then, the smaller the distance distribution between the rotating deviation clamps, and the more the number of rotating deviation clamps, the greater the effect of the centrifugal force generated by rotation on the clamps holding the target workpiece at the current time, so the rotating influence degree at the current time can be obtained according to the distance between the rotating deviation clamps at the current time and the number of rotating deviation clamps.

[0083] Preferably, in an embodiment of the present application, the method for obtaining the rotating influence degree at the current time specifically comprises:

[0084] The average of the distance between any two rotation offset clamps at the current time is taken as the rotation influence factor at the current time. The rotation influence factor at the current time and the number of rotation offset clamps are integrated and normalized, and the calculation result is limited in the range of [0, 1], so as to obtain the rotation influence degree at the current time.

[0085] As an example, in an embodiment of the present application, the expression of the rotation influence degree at the current time can be specifically, for example:

[0086] W=tanh(K×S)

[0087] Wherein, W represents the rotation influence degree at the current time; K represents the average of the distance between any two rotation offset clamps at the current time, i.e. the rotation influence factor at the current time; S represents the number of rotation offset clamps at the current time; tanh() represents the hyperbolic tangent function for normalization processing.

[0088] Further, according to the rotation influence degree at the current time, the clamping offset dominance of the target clamp at the current time is adjusted, so as to eliminate the interference of the centrifugal force generated by rotation on the improper clamping analysis of the target clamp, and the offset possibility of the target clamp at the current time is combined, so as to obtain the clamping offset interference degree of the target clamp at the current time.

[0089] Preferably, in an embodiment of the present application, the method for obtaining the clamping offset interference degree of the target clamp at the current time further comprises:

[0090] The product value of the rotation influence degree at the current time and the clamping offset dominance of the target clamp at the current time is taken as the clamping offset adjustment amount of the target clamp at the current time, and the difference between the clamping offset dominance of the target clamp at the current time and the clamping offset adjustment amount is taken as the adjusted clamping offset dominance of the target clamp at the current time. The adjusted clamping offset dominance reflects the possibility of the target clamp at the current time to appear offset phenomenon due to its own improper clamping after excluding the interference of the centrifugal force generated by rotation.

[0091] Then the adjusted clamping offset dominance of the target clamp at the current time and the offset possibility are integrated and normalized, and the calculation result is limited in the range of [0, 1], so as to obtain the clamping offset interference degree of the target clamp at the current time.

[0092] As an example, in an embodiment of the present application, the expression of the clamping offset interference degree of the target clamp at the current time can be specifically, for example:

[0093] Q=tanh(C×E ′ )

[0094] E′ =EW×E

[0095] Where Q represents the clamping offset disturbance degree of the target clamp at the current moment; C represents the offset probability of the target clamp at the current moment; E ′ E represents the dominance of the target fixture's clamping offset adjustment at the current moment; W represents the dominance of the target fixture's clamping offset at the current moment; W×E represents the amount of clamping offset adjustment of the target fixture at the current moment; tanh() represents the hyperbolic tangent function, used for normalization.

[0096] The clamping offset interference degree of each clamp holding the target workpiece at the current moment can be obtained by using the same method described above, as well as the clamping offset interference degree of each clamp holding each type of workpiece of the composite brake drum at the current moment.

[0097] Step S3: Take another workpiece as a reference workpiece, and take the clamping fixture that is closest to the target fixture and holds the reference workpiece as the reference fixture of the target fixture. Based on the difference in clamping offset interference between the target fixture and the reference fixture at the current moment, obtain the clamping imbalance of the target fixture at the current moment.

[0098] Because the different workpieces of the composite brake drum are made of different materials, their response to welding vibration varies, leading to different offsets. If the clamping offset interference obtained above is directly used to adjust the clamping pressure of the target fixture, it will increase the distance between the welds of different workpieces during subsequent welding, reducing the final welding effect. Therefore, it is necessary to analyze the differences in clamping offset interference between the fixtures holding different workpieces at the current moment. In this embodiment of the invention, another workpiece of the composite brake drum is first used as a reference workpiece, and the clamping reference workpiece closest to the target fixture is... The fixture for the target fixture serves as a reference fixture for the target fixture. The target fixture and the reference fixture each hold different workpieces, and the distance between them is the shortest, making them the most reliable references. The difference in clamping offset interference between the target fixture and the reference fixture at the current moment is analyzed to obtain the clamping imbalance of the target fixture at the current moment. The greater the clamping imbalance of the target fixture at the current moment, the greater the difference in offset tendency between the target fixture and the reference fixture when clamping different workpieces. This indicates that the clamping pressure applied by the target fixture at the current moment is more unbalanced, and therefore, the clamping pressure of the target fixture needs to be adjusted to a greater extent in the future.

[0099] Preferably, in one embodiment of the present invention, the method for obtaining the clamping imbalance of the target clamp at the current moment specifically includes:

[0100] The absolute value of the difference between the clamping offset interference degree between the target fixture and the reference fixture at the current time is normalized, and the calculation result is limited to the range of [0,1], so as to obtain the clamping imbalance degree of the target fixture at the current time.

[0101] As an example, in one embodiment of the present invention, the expression for the clamping imbalance of the target clamp at the current moment can be specifically as follows:

[0102] U = tanh(|QQ) ′ |)

[0103] Where U represents the clamping imbalance of the target clamp at the current moment; Q represents the clamping offset disturbance of the target clamp at the current moment; Q ′ This represents the clamping offset disturbance of the reference fixture at the current moment; tanh() represents the hyperbolic tangent function, used for normalization.

[0104] Step S4: Based on the clamping imbalance, control the clamping pressure of the target clamp at the next moment.

[0105] The greater the clamping imbalance of the target fixture at the current moment, the greater the difference in the offset tendency between the target fixture and the reference fixture when clamping different workpieces. This indicates that the clamping pressure applied by the target fixture at the current moment is more unbalanced, resulting in a smaller clamping pressure and requiring a greater increase in the clamping pressure applied by the target fixture. Therefore, the clamping pressure of the target fixture at the next moment can be controlled based on the clamping imbalance to avoid clamping offset of the target fixture during subsequent welding processes and improve the clamping effect of the target fixture.

[0106] Preferably, in one embodiment of the present invention, the method for controlling the clamping pressure of the target clamp at the next moment specifically includes:

[0107] The product of the clamping imbalance and pressure data of the target clamp at the current moment is used as the clamping pressure adjustment amount of the target clamp at the current moment. The sum of the pressure data of the target clamp at the current moment and the clamping pressure adjustment amount is used as the clamping pressure of the target clamp at the next moment.

[0108] As an example, in one embodiment of the present invention, the expression for the clamping pressure of the target clamp at the next moment can be specifically as follows:

[0109] F ′ =F + U × F

[0110] Among them, F ′F represents the clamping pressure of the target clamp at the next moment; F represents the pressure data of the target clamp at the current moment, that is, the clamping pressure of the target clamp at the current moment; U represents the clamping imbalance of the target clamp at the current moment.

[0111] By using the same method described above, the clamping pressure of each fixture holding each type of workpiece can be obtained at the next moment. Then, when welding enters the next moment, the clamping pressure of each fixture can be adjusted to avoid positional displacement of each fixture during the welding process.

[0112] It should be noted that the order of the above embodiments of the present invention is merely for descriptive purposes and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require a specific or sequential order to achieve the desired result. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0113] The various embodiments in this specification are described in a progressive manner. The same or similar parts between the various embodiments can be referred to each other. Each embodiment focuses on describing the differences from other embodiments.

Claims

1. A pressure control method for a multi-station positioning fixture used in welding composite brake drums, characterized in that, The method comprises: During welding of two workpieces of a composite brake drum, real-time acquisition of pressure data applied by each clamp of different workpieces is performed; Any workpiece of the composite brake drum is taken as a target workpiece, any clamp clamping the target workpiece is taken as a target clamp, a deviation possibility of the target clamp at a current time is obtained according to a distribution of pressure data of the target clamp at each time within a preset time period before the current time and a difference between pressure data of the target clamp and other clamps clamping the target workpiece at the current time, a clamping deviation dominance of the target clamp at the current time is obtained according to a difference between a distance from a welding position at the current time to the target clamp and a distance from the target clamp to a center of the target workpiece, and a clamping deviation interference degree of the target clamp at the current time is obtained according to the deviation possibility of the target clamp at the current time and the clamping deviation dominance of each clamp clamping the target workpiece at the current time; Another workpiece is taken as a reference workpiece, and a clamp clamping the reference workpiece closest to the target clamp is taken as a reference clamp of the target clamp, a clamping imbalance degree of the target clamp at the current time is obtained according to a difference between the clamping deviation interference degrees of the target clamp and the reference clamp at the current time; The clamping pressure of the target clamp at a next time is controlled based on the clamping imbalance degree.

2. A multi-station positioning clamp pressure control method for welding a composite brake drum as set forth in claim 1, characterized in that, The deviation possibility of the target clamp at the current time comprises: An average value of absolute values of differences between pressure data of all other clamps clamping the target workpiece and the target clamp at the current time is taken as a pressure difference characteristic value of the target clamp at the current time; A deviation coefficient of the target clamp at the current time is obtained according to a difference between the pressure difference characteristic values between the target clamp and other clamps clamping the target workpiece at the current time; A vibration interference degree of the target clamp at the current time is obtained by analyzing a discrete degree of pressure data of all times within a preset time period before the current time of the target clamp; The vibration interference degree and the deviation coefficient are integrated and normalized to obtain the deviation possibility of the target clamp at the current time.

3. A multi-station positioning clamp pressure control method for welding a composite brake drum as set forth in claim 2, characterized in that, The deviation coefficient of the target clamp at the current time comprises: An average value of absolute values of differences between the pressure difference characteristic values between all other clamps clamping the target workpiece and the target clamp at the current time is taken as the deviation coefficient of the target clamp at the current time.

4. The method of claim 1, wherein, The clamping deviation dominance of the target clamp at the current time comprises: If the distance from the welding position at the current time to the target clamp is less than the distance from the target clamp to the center of the target workpiece, an absolute value of a difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the center of the target workpiece is taken as a numerator, the distance from the target clamp to the center of the target workpiece is taken as a denominator, and a negative correlation normalization processing is performed on a ratio to obtain the clamping deviation dominance of the target clamp at the current time. If the distance from the welding position at the current time to the target clamp is not less than the distance from the target clamp to the target workpiece circle center, the absolute value of the difference between the distance from the welding position at the current time to the target clamp and the distance from the target clamp to the target workpiece circle center is taken as the numerator, the distance from the welding position at the current time to the target clamp is taken as the denominator, and the ratio is normalized to obtain the clamping offset dominance of the target clamp at the current time.

5. The method of claim 1, wherein, The obtaining of the clamping offset interference degree of the target clamp at the current time includes: Based on the clamping offset dominance of each clamp clamping the target workpiece at the current time, the clamping offset clamp of the target workpiece at the current time is selected from all clamps clamping the target workpiece; According to the distance between each of the clamping offset clamps at the current time and the number of clamping offset clamps, the rotation influence degree at the current time is obtained; According to the rotation influence degree at the current time, the clamping offset dominance of the target clamp at the current time is adjusted, and combined with the offset possibility of the target clamp at the current time, the clamping offset interference degree of the target clamp at the current time is obtained.

6. A multi-station positioning clamp pressure control method for welding a composite brake drum as defined in claim 5, wherein, The selection of the clamping offset clamp of the target workpiece at the current time from all clamps clamping the target workpiece includes: Among all clamps clamping the target workpiece, the clamps with a clamping offset dominance less than a preset offset threshold are taken as the clamping offset clamps at the current time.

7. The method of claim 5, wherein the pressure control method is characterized by, The obtaining of the rotation influence degree at the current time includes: The average value of the distance between any two clamping offset clamps at the current time is taken as the rotation influence factor at the current time; After the rotation influence factor at the current time and the number of clamping offset clamps are integrated and normalized, the rotation influence degree at the current time is obtained.

8. The method of claim 5, wherein the pressure control method is characterized by, The adjustment of the clamping offset dominance of the target clamp at the current time according to the rotation influence degree at the current time, and the combination of the offset possibility of the target clamp at the current time to obtain the clamping offset interference degree of the target clamp at the current time includes: The product value of the rotation influence degree at the current time and the clamping offset dominance of the target clamp at the current time is taken as the clamping offset adjustment amount of the target clamp at the current time; The difference between the clamping offset dominance of the target clamp at the current time and the clamping offset adjustment amount is taken as the adjusted clamping offset dominance of the target clamp at the current time; After the adjusted clamping offset dominance of the target clamp at the current time and the offset possibility are integrated and normalized, the clamping offset interference degree of the target clamp at the current time is obtained.

9. The method of claim 1, wherein, The obtaining of the clamping imbalance degree of the target clamp at the current time includes: The absolute value of the difference between the clamping offset interference degrees of the target clamp and the reference clamp at the current time is normalized to obtain the clamping imbalance degree of the target clamp at the current time.

10. The method of claim 1, wherein, The control of the clamping pressure of the target clamp at the next time based on the clamping imbalance degree includes: The product value of the clamping imbalance degree of the target clamp at the current time and the pressure data is taken as the clamping pressure adjustment amount of the target clamp at the current time; The sum of the pressure data of the target jig at the current time and the clamp pressure adjustment amount is set as the clamp pressure of the target jig at the next time.

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