Copper bar numerical control bending control method, device and system

Abstract

The invention relates to the technical field of numerical control machining, in particular to a numerical control bending control method, device and system for a copper bar. According to the method, a basic logic formula between the springback angle and the designed bending angle and a basic logic formula between the designed bending radius and the designed material thickness at each bending point position are built; the influence of the bending radius and the material thickness on the springback angle is analyzed, and the basic logic formula is corrected for the first time; the influence of the bending angle on the springback angle is analyzed, and secondary correction is conducted on the basic logic formula; and finally, the actual rebound angle is obtained, and bending of the copper bar workpiece is completed. According to the method, the springback amount is predicted in advance, and the compensation strategy is designed in a targeted mode, so that the number of times of trial bending is reduced, technological parameters are optimized, the machining precision is improved, and reworking or waste caused by springback out-of-tolerance is avoided.

Description

Technical Field

[0001] The present invention relates to the field of numerical control machining technology, and particularly to a numerical control bending control method, device and system for copper bars. Background Art

[0002] Numerical control bending of copper bars is a processing technology that precisely bends copper bars at a certain angle through a numerical control bending machine, mainly used in fields such as electrical equipment and power systems. By pre-programming and setting parameters, and combining with special molds, it can automatically bend copper bars, featuring high efficiency, high precision, and good repeatability. It can quickly complete the processing of complex shapes while maintaining the electrical conductivity and structural integrity of copper bars, and is widely used in the manufacturing of products such as busbars and switch cabinets.

[0003] During the numerical control bending process of copper bars, after the bending external force exerted by the mold on the workpiece is removed, the workpiece will undergo angular or shape changes due to the recovery of elastic deformation, forming the phenomenon of bending springback, resulting in a deviation between the actual bending angle and the angle set by the mold. It is necessary to control and adjust the processing process of the workpiece to ensure processing accuracy and workpiece consistency.

[0004] In the prior art, the method of over-bending compensation is often used to offset the bending springback of copper bars. However, the springback angle during bending is affected by thickness, bending radius, and bending angle, making it difficult to predict the springback angle after bending. A large number of experiments are required to obtain the corresponding over-bending compensation angle, and a large number of defective parts will be produced during this process, resulting in material waste. Summary of the Invention

[0005] In order to solve the above technical problems, the purpose of the present invention is to provide a numerical control bending control method, device and system for copper bars.

[0006] According to the first aspect of the embodiments of the present application, a numerical control bending control method for copper bars is provided, and the specific technical solution adopted is as follows:

[0007] Obtain the designed bending angle, designed bending radius, and designed material thickness of the bending point of the copper bar workpiece;

[0008] Construct a basic logical formula between the springback angle and the designed bending angle, designed bending radius, and designed material thickness at each bending point;

[0009] For any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, analyze the corresponding relationship between the bending pressure and the bending angle, and obtain the yield angle corresponding to each experimental parameter combination;

[0010] Adjust the bending radius and material thickness, and combine with the yield angle to correct the basic logical formula;

[0011] Bend the copper bar workpiece, analyze the difference in springback angles, and obtain the material change index corresponding to the preset bending angle of the experiment;

[0012] Adjust the preset bending angle, and in combination with the material change index, perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point;

[0013] According to the secondary corrected springback angle, in combination with the designed bending angle and the yield angle, obtain the actual springback angle at each bending point, and further determine the corrected preset bending angle at each bending point.

[0014] In some embodiments of the present invention, for any set of experimental parameter combinations formed by the experimental bending radius and the experimental material thickness, analyze the corresponding relationship between the bending pressure and the bending angle to obtain the yield angle corresponding to each experimental parameter combination, including:

[0015] Select the experimental bending radius and the experimental material thickness;

[0016] For any set of experimental parameter combinations formed by the experimental bending radius and the experimental material thickness, obtain the pressure time series and the angle time series;

[0017] Based on the pressure time series and the angle time series, analyze the change trends of the pressure difference and the angle difference corresponding to any moment and its adjacent moment, and obtain the yield index at any moment for each experimental parameter combination;

[0018] Record the angle value corresponding to the moment with the maximum yield index as the yield angle corresponding to the experimental parameter combination.

[0019] In some embodiments of the present invention, adjust the bending radius and the material thickness, and in combination with the yield angle, correct the basic logic formula, including:

[0020] Record the ratio of the bending radius to the material thickness as the deformation gradient index;

[0021] Select the experimental bending radius and the experimental material thickness to obtain the experimental deformation gradient index;

[0022] According to the experimental deformation gradient index, in combination with the yield angle, perform curve fitting on the copper bar workpieces of all parameter combinations using the least squares method for the deformation gradient index and the bending gain index to obtain the bending gain index corresponding to each deformation gradient index;

[0023] According to the bending gain index, correct the basic logic formula to obtain the corrected springback angle at each bending point.

[0024] In some embodiments of the present invention, according to the experimental deformation gradient index and in combination with the yield angle, the curve fitting of the deformation gradient index and the bending gain index for the copper bar workpieces of all parameter combinations is performed by the least squares method to obtain the bending gain index corresponding to each deformation gradient index, including:

[0025] Analyze the difference between any deformation gradient index and each experimental deformation gradient index, and analyze the magnitude relationship between the yield angle corresponding to any parameter combination and the yield angle corresponding to the experimental parameter combination. Then, perform the curve fitting of the deformation gradient index and the bending gain index for the copper bar workpieces of all parameter combinations by the least squares method to obtain the bending gain index corresponding to each deformation gradient index.

[0026] In some embodiments of the present invention, the copper bar workpieces are bent, and the difference in the springback angle is analyzed to obtain the material change index corresponding to the preset bending angle of the experiment, including:

[0027] Perform two bending experiments with the same preset bending angle at the same position of the copper bar workpiece, analyze the difference in the springback angles corresponding to the two bending experiments, and obtain the material change index corresponding to the preset bending angle of the experiment.

[0028] In some embodiments of the present invention, after obtaining the material change index of the copper bar workpiece, it further includes: according to the material change index corresponding to the preset bending angle of the experiment, obtain the estimated material change index corresponding to any untested preset bending angle.

[0029] In some embodiments of the present invention, adjust the preset bending angle, and in combination with the material change index, perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point, including:

[0030] Adjust the preset bending angle, and in combination with the estimated material change index, perform the curve fitting of the bending pressure corresponding to the preset bending angle and the springback angle by the least squares method to obtain the actual springback angle corresponding to each bending pressure;

[0031] According to the actual springback angle, perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point.

[0032] In some embodiments of the present invention, according to the secondary corrected springback angle, in combination with the designed bending angle and the yield angle, obtain the actual springback angle at each bending point, and further determine the corrected preset bending angle at each bending point, including:

[0033] Judge whether the designed bending angle at the bending point is less than the yield angle corresponding to the bending point;

[0034] If so, the actual springback angle is equal to the designed bending angle;

[0035] If not, the actual springback angle is equal to the secondary corrected springback angle;

[0036] Determine the corrected preset bending angle of each bending point according to the actual springback angle and the designed bending angle.

[0037] According to the second aspect of the embodiments of the present application, a copper bar numerical control bending control device is provided, and the device includes:

[0038] A data acquisition module, configured to obtain the designed bending angle, designed bending radius, and designed material thickness of the bending points of the copper bar workpiece;

[0039] A basic logic formula construction module, configured to construct a basic logic formula between the springback angle and the designed bending angle, the designed bending radius and the designed material thickness at each bending point;

[0040] A basic logic formula correction module, configured to analyze the corresponding relationship between the bending pressure and the bending angle for any set of parameter combinations formed by the bending radius and the material thickness, obtain the yield angle corresponding to each parameter combination; and adjust the bending radius and the material thickness, and correct the basic logic formula in combination with the yield angle;

[0041] A basic logic formula secondary correction module, bend the copper bar workpiece, analyze the difference in the springback angle, obtain the material change index corresponding to the preset bending angle of the experiment; and adjust the preset bending angle, and perform secondary correction on the corrected basic logic formula in combination with the material change index to obtain the secondary corrected springback angle of each bending point;

[0042] A preset bending angle determination module, configured to obtain the actual springback angle of each bending point according to the secondary corrected springback angle, in combination with the designed bending angle and the yield angle, and further determine the corrected preset bending angle of each bending point.

[0043] According to the third aspect of the embodiments of the present application, a copper bar numerical control bending control system is provided, and the system includes a memory and a processor, wherein:

[0044] The memory is used to store program codes;

[0045] The processor is configured to read the program codes stored in the memory and execute the method according to any one of the first aspects of the embodiments of the present application.

[0046] Compared with the prior art, a copper bar numerical control bending control method, device and system provided by the present invention have the following beneficial effects:

[0047] The present invention first constructs a basic logical formula between the springback angle at each bending point, the designed bending angle, the designed bending radius, and the designed material thickness. Then, for any set of experimental parameter combinations formed by the experimental bending radius and the experimental material thickness, the corresponding relationship between the bending pressure and the bending angle is analyzed to obtain the yield angle corresponding to each experimental parameter combination. Furthermore, the bending radius and the material thickness are adjusted, and combined with the yield angle, the basic logical formula is corrected to complete the correction of the influence of the bending radius and the material thickness on the springback angle. Then, by bending the copper bar workpiece, the difference in the springback angle is analyzed to obtain the material change index corresponding to the preset bending angle of the experiment. And the preset bending angle is adjusted, and combined with the material change index, the corrected basic logical formula is corrected again to obtain the secondary corrected springback angle at each bending point, and the correction of the influence of the bending angle on the springback angle is completed. Finally, according to the secondary corrected springback angle, combined with the designed bending angle and the yield angle, the actual springback angle at each bending point is obtained, and then the corrected preset bending angle at each bending point is determined. Before bending the copper bar workpiece, the present invention analyzes the springback angle from the design angle of the copper bar workpiece through the parameters at the bending points, which can optimize the process parameters and improve the processing accuracy. By analyzing the geometric features at the bending points in the CAD design drawing and combining with the sample data, the springback amount can be predicted in advance and a targeted compensation strategy can be designed, so as to reduce the number of trial bendings and avoid rework or waste caused by excessive springback. At the same time, based on the springback distribution information at the bending points, the layout of sensors and the real-time monitoring of key areas can be guided to ensure the forming accuracy and consistency of copper bars with complex shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] In order to more clearly illustrate the technical solutions and advantages in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained according to these drawings.

[0049] Figure 1 It is a schematic flowchart of the basic process of a copper bar numerical control bending control method provided by an embodiment of the present invention;

[0050] Figure 2 It is a schematic diagram of the basic composition of a copper bar numerical control bending control device provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0051] To further elaborate on the technical means and effects adopted by the present invention to achieve the intended invention purpose, the following specifically describes, with reference to the accompanying drawings and preferred embodiments, a copper bar numerical control bending control method, device, and system proposed according to the present invention, including its specific implementation manner, structure, features, and effects. 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.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which the present invention belongs. Terms such as "including", "comprising", or any other variant thereof are intended to cover non-exclusive inclusion, such that a circuit structure, article, or system including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such article or system. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of another identical element in the article or system including the element. Relative terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations.

[0053] The following specifically describes the specific solution of a copper bar numerical control bending control method provided by the present invention with reference to the accompanying drawings.

[0054] Please refer to Figure 1 , which shows the basic process of a copper bar numerical control bending control method provided by an embodiment of the present invention.

[0055] As Figure 1 shown, a copper bar numerical control bending control method provided by an embodiment of the present invention specifically includes:

[0056] S100: Obtain the designed bending angle, designed bending radius, and designed material thickness of the bending points of the copper bar workpiece.

[0057] The CAD (Computer-Aided Design) design drawings of the copper plate workpiece generally mark the bending angle, bending radius, and material thickness of the copper plate at each bending point. Therefore, first obtain the CAD drawings of the copper plate workpiece, and extract all the bending points of the copper plate workpiece from the CAD drawings; for any bending point, obtain the designed bending angle, designed bending radius, and designed material thickness of this bending point, and perform standardization processing on each parameter to eliminate the dimension.

[0058] S200: Construct the basic logical formula between the springback angle, the designed bending angle, the designed bending radius, and the designed material thickness at each bending point to obtain the possible springback angle at each bending point.

[0059] The springback angle of the copper busbar is mainly closely related to its material thickness, bending angle, and bending radius. The larger the material thickness, the higher the proportion of plastic deformation of the material, the relatively smaller the elastic recovery amount, and the smaller the springback; the larger the bending angle or the bending radius, the greater the cumulative amount of elastic deformation in the bending area of the material, and the more significant the springback phenomenon. Based on this, the possible springback angle at each bending point can be preliminarily calculated.

[0060] Based on the above analysis, in the embodiment of the present invention, by constructing the basic logical formula between the springback angle, the designed bending angle, the designed bending radius, and the designed material thickness at each bending point, the possible springback angle at each bending point is obtained. Specifically, the calculation method of the possible springback angle at the

[0061]

[0062] bending point is as follows: where represents the possible springback angle at the th bending point; represents the designed material thickness at the th bending point; represents the designed bending angle at the th bending point; represents the designed bending radius at the

[0063] th bending point. It should be noted that there is no possibility that the designed material thickness at any bending point is zero.

[0064] After obtaining the possible springback angle at each bending point, in order to offset the springback phenomenon caused by the elastic deformation of the material, overbending compensation is carried out during the bending process of the copper busbar. By presetting the bending angle to the sum of the designed bending angle and the predicted springback angle in advance, the designed bending angle can be accurately achieved after springback.

[0065] Since the method for obtaining the possible springback angle of the bending point conforms to the basic law of copper busbar springback in trend, but there may be a problem of significant error under extreme parameters during the actual bending process, it is necessary to adjust according to the actual bending situation during the actual bending process, thereby reducing the error during the actual bending process.

[0066] By conducting a trial bend on the copper busbar, the possible springback angle quantified according to the CAD design drawing is mapped to the actual bending springback process, so as to obtain a more accurate springback angle.

[0067] Taking the ratio of the bending radius to the material thickness as the core parameter to reflect the deformation gradient during material bending. The larger the ratio, the more significant the outer layer stretching during large-radius bending of the thin plate, the greater the elastic recovery space, and the stronger the springback. Therefore, first analyze the influence of the bending radius and material thickness on the springback angle. Specifically, it includes step S300 and step S400.

[0068] S300: For any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, analyze the corresponding relationship between the bending pressure and the bending angle to obtain the yield angle corresponding to each experimental parameter combination.

[0069] For any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, analyze the corresponding relationship between the bending pressure and the bending angle to obtain the yield angle corresponding to each experimental parameter combination. Further, it includes:

[0070] First, select the experimental bending radius and experimental material thickness. Specifically, among all possible bending radii, uniformly select 5 bending radii from the maximum bending radius to the minimum bending radius as the experimental bending radii; similarly, among all possible material thicknesses, uniformly select 5 material thicknesses from the maximum material thickness to the minimum material thickness as the experimental material thicknesses.

[0071] Then, for any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, obtain the pressure time series and the angle time series. Specifically, according to any one experimental bending radius and one experimental material thickness, select the matching upper die and lower die, install the dies on the slider and the workbench of the numerical control bending machine, and calibrate the concentricity; install a pressure sensor on the upper die; take 90 degrees as the preset bending angle, input the preset bending angle into the numerical control system. After the numerical control bending machine starts, the numerical control bending machine bends the copper bar, obtains the three-dimensional point cloud data through a laser scanner, obtains the actually monitored actual bending angle through the included angle between the normal vectors of two planes, and obtains the pressure time series and the angle time series. The acquisition frequencies of the two series are the same; take the difference between the preset bending angle and the final bending angle as the springback angle. Obtain the springback angle corresponding to each combination of the experimental bending radius and experimental material thickness according to the above method.

[0072] Then, based on the pressure time series and the angle time series, analyze the change trends of the pressure difference and the angle difference corresponding to any moment and its adjacent moment, and obtain the yield index at any moment for each experimental parameter combination. Specifically, in the initial stage of bending, the material is in the elastic deformation zone, and the stress-strain is proportional (Hooke's law). The external force does not exceed the elastic limit of the material, that is, it does not enter the plastic deformation stage, and the bent material will return to its original state completely. After the stress exceeds the yield strength, the material enters the plastic deformation stage. At this time, the stress growth slows down, but the accumulated elastic strain energy increases non-linearly with the increase of the deformation amount, resulting in an accelerated increase in the springback amount. Therefore, the springback angle is positively correlated and non-linearly increasing with the parameter combination formed by the bending radius and the material thickness. Therefore, for the pressure time series and the angle time series of any experimental parameter combination of the experimental bending radius and the experimental material thickness, the yield index at the

[0073]

[0074] th moment is calculated as follows: In the formula, represents the yield index of the th experimental parameter combination at the th moment; represents the pressure value at the th moment in the pressure time series of the th experimental parameter combination; represents the angle value at the th moment in the angle time series of the th experimental parameter combination; represents the pressure value at the th moment in the pressure time series of the th experimental parameter combination; represents the angle value at the th moment in the angle time series of the represents the pressure value at the th moment in the pressure time series of the th experimental parameter combination; represents the angle value at the th moment in the angle time series of the th experimental parameter combination; Adding 0.1 is to prevent the denominator from being 0.

[0075] Finally, since each copper bar has exactly one yield point during the process from elastic deformation to plastic deformation, and the pressure changes abruptly at the moment when this yield point is reached, the angle value corresponding to the moment with the maximum yield index is recorded as the yield angle corresponding to the experimental parameter combination.

[0076] S400: Adjust the bending radius and material thickness, and combine with the yield angle to correct the basic logic formula, obtaining the corrected springback angle for each bending point.

[0077] Before entering plastic deformation, the material undergoes a longer elastic deformation stage and accumulates more elastic strain energy. During unloading, this part of the energy drives elastic recovery, resulting in a larger absolute value of the springback angle. For copper bars with parameter combinations having a high yield angle, the rate of increase of elastic strain energy with the bending angle is faster, leading to a corresponding increase in the growth rate of the springback angle.

[0078] Therefore, after obtaining the yield angle corresponding to each experimental parameter combination, by adjusting the bending radius and material thickness, and combining with the yield angle, the basic logic formula is corrected to obtain the corrected springback angle for each bending point. Further, it includes:

[0079] First, record the ratio of the bending radius to the material thickness as the deformation gradient index; and select the experimental bending radius and experimental material thickness to obtain the experimental deformation gradient index.

[0080] Then, according to the experimental deformation gradient index, combine with the yield angle, and use the least squares method to perform curve fitting of the deformation gradient index and the bending gain index for the copper bar workpieces of all parameter combinations, obtaining the bending gain index corresponding to each deformation gradient index. Specifically, analyze the difference between any deformation gradient index and each experimental deformation gradient index, and analyze the magnitude relationship between the yield angle corresponding to any parameter combination and the yield angle corresponding to the experimental parameter combination, and use the least squares method to perform curve fitting of the deformation gradient index and the bending gain index for the copper bar workpieces of all parameter combinations, obtaining the bending gain index corresponding to each deformation gradient index. It should be noted that there is a one-to-one correspondence between the deformation gradient index and the parameter combination formed by the bending radius and the material thickness.

[0081] The th parameter combination (i.e., the th deformation gradient index) of the copper bar, the calculation method of the bending gain index is:

[0082]

[0083] In the formula, represents the bending gain index of the copper bar of the th parameter combination (the th deformation gradient index); represents the number of experimental parameter combinations (experimental deformation gradient index); represents the experimental deformation gradient index corresponding to the th experimental parameter combination; represents the th parameter combination (the The deformation gradient index of the copper bar (with a deformation gradient index); Indicates the Yield angle corresponding to the Indicates the th parameter combination; The yield angle corresponding to the copper bar with the th parameter combination (with the Indicates the normalization function that converts a real vector into a probability distribution; Indicates the maximum value function; exp represents the exponential function with the natural constant e as the base.

[0084] When the deformation gradient index, i.e., the ratio of the bending radius to the material thickness, increases, to achieve the same yield strain (an intrinsic property of the material), a larger bending angle is required to compensate for the insufficient strain accumulation, so the yield angle will be larger. That is, the yield angle and the deformation gradient index are positively correlated (both increase or decrease together) but non-linearly related, and it is a curve with a trend-changing slope. To determine the th parameter combination, the is used to determine the th parameter combination and the th parameter combination, the distance between the deformation gradient indices. When is larger, it indicates that the deformation gradient indices of the copper bars are closer, that is, the distance is smaller, and it can better reflect the th parameter combination, the rate of change of the yield angle nearby; through the ratio describes the rate of change of the yield angle.

[0085] Based on the sample data, curve fitting is performed on the deformation gradient index and the bending gain index, that is, the sample data is used to fit the complete curve corresponding to the deformation gradient index and the bending gain index, and then each corresponding is obtained.

[0086] It should be noted that one deformation gradient index corresponds to one bending gain index, but the parameter combinations in the actual processing may not appear in the known sample data. That is, in the actual processing, some deformation gradient indices do not have corresponding bending gain indices because they are different from all known samples. Therefore, it is necessary to fit all the samples into a curve, that is, use some samples to fit the complete curve corresponding to the deformation gradient index and the bending gain index.

[0087] Finally, based on the bending gain index, the basic logical formula is corrected to obtain the corrected springback angle at each bending point. Specifically, the calculation formula for the corrected springback angle at the th bending point is constructed as:

[0088]

[0089] In the formula, represents the corrected springback angle of the th bending point; represents the designed material thickness at the th bending point; represents the designed bending angle at the th bending point; represents the designed bending radius at the th bending point; represents the bending gain index of the parameter combination corresponding to the designed bending radius and the designed material thickness at the th bending point.

[0090] Thus, the correction of the influence of the bending radius and the material thickness on the springback angle is completed.

[0091] The foregoing steps explored the influence relationship between the bending radius and the material thickness on the springback angle. In the actual bending process, in order to make the angle of the finished copper busbar conform to the industrial standard after bending, an over-bending compensation method is often adopted, that is, bending is performed at an angle larger than the designed bending angle. Therefore, the influence of the bending angle on the springback angle also needs to be considered.

[0092] S500: Bend the copper busbar workpiece, analyze the difference in the springback angle, and obtain the material change index corresponding to the preset bending angle of the experiment.

[0093] Bend the copper bar workpiece, analyze the difference in springback angles, and obtain the material change index corresponding to the preset bending angle of the experiment. Further, it includes: conduct two bending experiments with the same preset bending angle at the same position of the copper bar workpiece, analyze the difference in springback angles corresponding to the two bending experiments, and obtain the material change index corresponding to the preset bending angle of the experiment. Specifically, according to any experimental bending radius and an experimental material thickness, select a matching upper die and lower die, install the die on the slider and workbench of the numerical control bending machine, and calibrate the concentricity; install a pressure sensor on the upper die; take any bending angle as the preset bending angle, input the preset bending angle into the numerical control system. After the numerical control bending machine starts, the numerical control bending machine bends the copper bar for the first time, obtains three-dimensional point cloud data through a laser scanner, and obtains the real-time monitored actual bending angle through the included angle of the normal vectors of two planes, to obtain a pressure time series and an angle time series, and the acquisition frequencies of the two series are the same; take the difference between the preset bending angle and the final bending angle as the springback angle. Then use the numerical control bending machine to bend the same position of the copper bar for the second time, and the degree of bending is the same as the first time (that is, the degree of bending of the copper bar before unloading is the same for both times). Although the degree of bending is the same, due to the state change of the material after the first deformation, including work hardening, residual stress, microstructure adjustment, etc., the springback angles for the two times are different. Therefore, analyze the difference in springback angles corresponding to the two bending experiments, and the material change index corresponding to the preset bending angle of the experiment is:

[0094]

[0095] In the formula, represents the material change index corresponding to the preset bending angle of the experiment; represents the first springback angle under the preset bending angle of the experiment, represents the second springback angle under the preset bending angle of the experiment.

[0096] Usually, the springback angle is the most significant after the first plastic deformation. When bending the same angle for the second time, due to the irreversible state change of the copper bar after the first bending, such as work hardening and redistribution of residual stress, the springback angle for the second time is different. The material change index directly quantifies the deviation of the springback characteristics after the first plastic deformation of the material, and reflects the influence degree of work hardening on the material.

[0097] S600: Obtain the estimated material change index corresponding to any untested preset bending angle according to the material change index corresponding to the preset bending angle of the experiment.

[0098] When the mold is about to release the bending force, theoretically, when the pressure is the same, the springback angle should also be the same. However, due to different bending angles of the material, the material change index of the material is also different, resulting in different springback angles. Therefore, according to the material change index corresponding to the preset bending angle of the experiment, the estimated material change index corresponding to any untested preset bending angle is obtained. Specifically, for any untested preset bending angle, select the two preset bending angles of the experiment that are closest to the untested preset bending angle; analyze the proportional relationship between the difference between the two closest preset bending angles of the experiment and the difference between their corresponding material change indexes, and combine the untested preset bending angle to obtain the estimated material change index corresponding to any untested preset bending angle. The calculation method of the estimated material change index of the untested preset bending angle is as follows:

[0099]

[0100] In the formula, represents the estimated material change index of the untested preset bending angle; represents one of the material change indexes of the two preset bending angles of the experiment that are closest to the untested preset bending angle; represents the other material change index of the two preset bending angles of the experiment that are closest to the untested preset bending angle; represents one of the bending angles of the two preset bending angles of the experiment that are closest to the untested preset bending angle; represents the other bending angle of the two preset bending angles of the experiment that are closest to the untested preset bending angle; represents the untested preset bending angle; adding is to prevent the denominator from being 0.

[0101] S700: Adjust the preset bending angle, combine the material change index, and perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point.

[0102] Due to the change in the material state, the springback angle changes under the same pressure. Therefore, in order to obtain the designed bending angle after springback, it is necessary to compensate and correct the preset bending angle. Therefore, adjust the preset bending angle, combine the material change index, and perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point. Further, it includes:

[0103] First, adjust the preset bending angle, combine the estimated material change index, and use the least squares method to perform curve fitting on the bending pressure corresponding to the bending angle and the springback angle, so as to obtain the corresponding relationship between each preset bending angle and the actual springback angle.

[0104] Construct the following relationship:

[0105]

[0106] In the formula, represents the preset bending angle; represents the pressure corresponding to the preset bending angle (since the preset bending angle and pressure are monitored in real time, the corresponding relationship can be obtained in the sequence); represents the first parameter to be fitted; represents the actual springback angle corresponding to the preset bending angle; represents the second parameter to be fitted; represents the third parameter to be fitted; represents the estimated material change index of the preset bending angle that has not been experimented.

[0107] Thus, we get:

[0108]

[0109] According to the sample data of the preset bending angle that has been experimented, use the least squares method to perform curve fitting on the bending pressure and springback angle corresponding to the preset bending angle, and obtain the fitted , and , that is, we get:

[0110]

[0111] It should be noted that the preset bending angle obtained here is actually a correction of the designed bending angle.

[0112] Therefore, according to the preset bending angle, perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point. Specifically, in the calculation formula of the springback angle, replace the designed bending angle with the preset bending angle , so as to improve the accuracy of subsequent fitting of the springback angle.

[0113]

[0114] In the formula, represents the secondary corrected springback angle at the th bending point; represents the designed material thickness at the th bending point; represents the designed bending radius at the th bending point; represents the The bending gain index of the parameter combination corresponding to the designed bending radius and the designed material thickness at a bending point; Indicates the preset bending angle at the th bending point; Indicates the actual springback angle at the th bending point; Indicates the first fitting parameter; Indicates the second fitting parameter; Indicates the estimated material change index of the preset bending angle that has not been experimented.

[0115] It should be noted that the secondary corrected springback angle in this formula and the actual springback angle

[0116]

[0117] have the same meaning and value, both representing the final actual springback angle after correction. Therefore, the above formula can be transformed into:

[0118] S800: According to the secondary corrected springback angle, combined with the designed bending angle and the yield angle, obtain the actual springback angle at each bending point, and then determine the corrected preset bending angle at each bending point.

[0119] According to the secondary corrected springback angle, combined with the designed bending angle and the yield angle, obtain the actual springback angle at each bending point, and then determine the corrected preset bending angle at each bending point. Further including:

[0120] First, determine whether the designed bending angle at the bending point is less than the corresponding yield angle at the bending point; if so, the actual springback angle is equal to the designed bending angle; if not, the actual springback angle is equal to the secondary corrected springback angle. Therefore, the actual springback angle is obtained as:

[0121]

[0122] In the formula, Indicates the actual springback angle at the th bending point; Indicates the designed bending angle at the th bending point; Indicates the yield angle corresponding to the parameter combination (the parameter combination composed of the designed bending radius and the designed material thickness at the th bending point) at the The designed material thickness at a bending point Indicates the Designed bending radius at the Indicates the Bending gain index of the parameter combination corresponding to the designed bending radius and the designed material thickness at the Indicates the Preset bending angle at the Indicates the first fitting parameter Indicates the second fitting parameter Indicates the third fitting parameter Indicates the estimated material change index of the preset bending angle that has not been experimented

[0123] Then, according to the actual springback angle and the designed bending angle, determine the corrected preset bending angle for each bending point. Specifically, during the CAD drawing design, substitute the designed bending radius, bending angle, and material thickness into the above formula to obtain the springback angle. When the springback angle is greater than the preset springback angle, it indicates that there is an abnormality in the design, and the CAD design drawing needs to be adjusted

[0124] Before officially bending the copper bar, it is necessary to over-bend the copper bar according to the designed bending angle and the springback angle, so that the difference between the preset bending angle and the springback angle is equal to the designed bending angle of the copper bar workpiece, that is, over-bend the copper bar

[0125]

[0126] In the formula Indicates the Corrected preset bending angle of the copper bar at the Indicates the Actual springback angle at the Indicates the Designed bending angle at the

[0127] Furthermore, according to the corrected preset bending angle of the copper bar at each bending point, bend the copper bar

[0128] Based on the same inventive concept as the above method, this embodiment also provides a numerical control bending control device for copper bars

[0129] Please refer to Figure 2 , which shows the basic composition of a numerical control bending control device for copper bars provided by an embodiment of the present invention

[0130] As shown in Figure 2As shown in the figure, a numerical control bending control device for copper bars includes: a data acquisition module 1, a basic logic formula construction module 2, a basic logic formula correction module 3, a secondary basic logic formula correction module 4, and a preset bending angle determination module 5. Among them:

[0131] The data acquisition module 1 is used to obtain the designed bending angle, designed bending radius, and designed material thickness of the bending points of the copper bar workpiece;

[0132] The basic logic formula construction module 2 is used to construct the basic logic formula between the springback angle, designed bending angle, designed bending radius, and designed material thickness at each bending point, and obtain the possible springback angles at each bending point;

[0133] The basic logic formula correction module 3 is used to analyze the corresponding relationship between the bending pressure and the bending angle for any set of parameter combinations formed by the bending radius and the material thickness, obtain the yield angle corresponding to each parameter combination; and adjust the bending radius and the material thickness, and combine the yield angle to correct the basic logic formula to obtain the corrected springback angle at each bending point;

[0134] The secondary basic logic formula correction module 4 bends the copper bar workpiece, analyzes the difference in the springback angle, and obtains the material change index corresponding to the preset bending angle of the experiment; and adjusts the preset bending angle, and combines the material change index to perform secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point;

[0135] The preset bending angle determination module 5 is used to obtain the actual springback angle at each bending point according to the secondary corrected springback angle, and combine the designed bending angle and the yield angle, and further determine the corrected preset bending angle at each bending point.

[0136] Based on the same inventive concept as the above method, this embodiment also provides a numerical control bending control system for copper bars.

[0137] The system includes a memory and a processor, where:

[0138] The memory is used to store program codes;

[0139] A processor is configured to read program code stored in a memory and execute the following operations: obtain the designed bending angle, designed bending radius, and designed material thickness of the bending points of a copper bar workpiece; construct basic logical formulas between the springback angle and the designed bending angle, between the designed bending radius and the designed material thickness at each bending point; for any set of experimental parameter combinations formed by an experimental bending radius and an experimental material thickness, analyze the corresponding relationship between the bending pressure and the bending angle to obtain the yield angle corresponding to each experimental parameter combination; adjust the bending radius and the material thickness, and combine with the yield angle to correct the basic logical formula; bend the copper bar workpiece, analyze the difference in the springback angle to obtain the material change index corresponding to the preset bending angle of the experiment; adjust the preset bending angle, and combine with the material change index to perform a secondary correction on the corrected basic logical formula to obtain the secondary corrected springback angle of each bending point; according to the secondary corrected springback angle, combine with the designed bending angle and the yield angle to obtain the actual springback angle of each bending point, and further determine the corrected preset bending angle of each bending point.

[0140] It should be noted that the above sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. The processes depicted in the accompanying drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0141] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and the key point of each embodiment is to illustrate the differences from other embodiments.

Claims

1. A numerical control bending control method for copper bars, characterized in that, The method includes: Obtaining the designed bending angle, designed bending radius, and designed material thickness at the bending points of the copper bar workpiece; Constructing a basic logical formula between the springback angle, designed bending angle, designed bending radius, and designed material thickness at each bending point; For any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, analyzing the corresponding relationship between the bending pressure and the bending angle to obtain the yield angle corresponding to each experimental parameter combination; Adjusting the bending radius and material thickness, and combining with the yield angle, correcting the basic logical formula; Bending the copper bar workpiece, analyzing the difference in the springback angle to obtain the material change index corresponding to the preset bending angle of the experiment; Adjusting the preset bending angle, and combining with the material change index, performing a secondary correction on the corrected basic logical formula to obtain the secondary corrected springback angle at each bending point; According to the secondary corrected springback angle, combining with the designed bending angle and the yield angle, obtaining the actual springback angle at each bending point, and further determining the corrected preset bending angle at each bending point.

2. The copper bar numerical control bending control method according to claim 1, characterized in that For any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, analyzing the corresponding relationship between the bending pressure and the bending angle to obtain the yield angle corresponding to each experimental parameter combination, including: Selecting the experimental bending radius and experimental material thickness; For any set of experimental parameter combinations formed by the experimental bending radius and experimental material thickness, obtaining the pressure time series and the angle time series; Based on the pressure time series and the angle time series, analyzing the change trend of the pressure difference and the angle difference corresponding to any moment and its adjacent moment to obtain the yield index of each experimental parameter combination at any moment; Recording the angle value corresponding to the moment with the maximum yield index as the yield angle corresponding to the experimental parameter combination.

3. The copper bar numerical control bending control method according to claim 2, wherein, Adjusting the bending radius and material thickness, and combining with the yield angle, correcting the basic logical formula, including: Denoting the ratio of the bending radius to the material thickness as the deformation gradient index; Selecting the experimental bending radius and experimental material thickness to obtain the experimental deformation gradient index; According to the experimental deformation gradient index, combining with the yield angle, performing curve fitting of the deformation gradient index and the bending gain index for the copper bar workpieces of all parameter combinations by using the least square method to obtain the bending gain index corresponding to each deformation gradient index; Correcting the basic logical formula according to the bending gain index.

4. The copper bar numerical control bending control method according to claim 3, characterized in that, According to the experimental deformation gradient index, combining with the yield angle, performing curve fitting of the deformation gradient index and the bending gain index for the copper bar workpieces of all parameter combinations by using the least square method to obtain the bending gain index corresponding to each deformation gradient index, including: Analyze the difference between any deformation gradient index and each of the experimental deformation gradient indices, and analyze the magnitude relationship between the yield angle corresponding to any parameter combination and the yield angle corresponding to the experimental parameter combination. For the copper bar workpieces of all parameter combinations, use the least squares method to perform curve fitting of the deformation gradient index and the bending gain index to obtain the bending gain index corresponding to each deformation gradient index.

5. The copper busbar numerical control bending control method according to claim 1, wherein Bend the copper bar workpiece and analyze the difference in the springback angle to obtain the material change index corresponding to the preset bending angle of the experiment, including: Perform a bending experiment with the same preset bending angle twice on the same position of the copper bar workpiece, analyze the difference in the springback angles corresponding to the two bending experiments, and obtain the material change index corresponding to the preset bending angle of the experiment.

6. The copper bar numerical control bending control method according to claim 5, wherein Obtain the material change index of the copper bar workpiece. Subsequently, it further includes: According to the material change index corresponding to the preset bending angle of the experiment, obtain the estimated material change index corresponding to any untested preset bending angle.

7. The copper busbar numerical control bending control method according to claim 6, characterized in that, Adjust the preset bending angle, and in combination with the material change index, perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point, including: Adjust the preset bending angle, and in combination with the estimated material change index, use the least squares method to perform curve fitting of the bending pressure corresponding to the preset bending angle and the springback angle to obtain the actual springback angle corresponding to each bending pressure; According to the actual springback angle, perform a secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle at each bending point.

8. The copper busbar numerical control bending control method according to claim 1, characterized in that, According to the secondary corrected springback angle, in combination with the designed bending angle and the yield angle, obtain the actual springback angle at each bending point, and further determine the corrected preset bending angle at each bending point, including: Judge whether the designed bending angle at the bending point is less than the yield angle corresponding to the bending point; If so, the actual springback angle is equal to the designed bending angle; If not, the actual springback angle is equal to the secondary corrected springback angle; Determine the corrected preset bending angle at each bending point according to the actual springback angle and the designed bending angle.

9. A numerical control bending control device for copper busbars, characterized in that, The device includes: A data acquisition module for obtaining the designed bending angle, designed bending radius, and designed material thickness at the bending point of the copper bar workpiece; A basic logic formula construction module for constructing a basic logic formula between the springback angle and the designed bending angle, designed bending radius, and designed material thickness at each bending point; A basic logic formula correction module for analyzing the corresponding relationship between the bending pressure and the bending angle for any parameter combination formed by the bending radius and the material thickness to obtain the yield angle corresponding to each parameter combination; and adjusting the bending radius and the material thickness, and in combination with the yield angle, correct the basic logic formula. The basic logic formula secondary correction module bends the copper bar workpiece, analyzes the differences in springback angles, and obtains the material change index corresponding to the preset bending angle of the experiment; and adjusts the preset bending angle, combines the material change index, and performs secondary correction on the corrected basic logic formula to obtain the secondary corrected springback angle of each bending point. The preset bending angle determination module is used to obtain the actual springback angle of each bending point based on the secondary corrected springback angle, in combination with the designed bending angle and the yield angle, and further determine the corrected preset bending angle of each bending point.

10. A numerical control bending control system for copper bars, characterized in that, The system includes a memory and a processor, where: The memory is used to store program codes; The processor is used to read the program codes stored in the memory and execute the method according to any one of claims 1 to 8.

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