A method for controlling the welding quality of the terminal of a hairpin motor

Abstract

The present invention discloses a method for controlling the welding quality of the terminal of a hairpin motor, belonging to the field of welding technology. By the corresponding setting of a CCD imaging module, an OCT detection module and a laser welding system, it can realize the status monitoring of each link before, during and after the terminal welding process, provide a basis for the adjustment of process parameters during the laser welding process of the terminal, and realize the real-time monitoring of each link of the terminal welding process and the dynamic adjustment of the terminal processing process parameters. The method for controlling the welding quality of the terminal of the hairpin motor in the present invention has a compact structure and convenient control, can realize the welding of the terminal of the hairpin motor, accurately scan and monitor the processing part of the motor terminal in each time period of the welding, realize the closed-loop control of the welding process, complete the quality control of the welding of the terminal of the hairpin motor, improve the yield rate and processing efficiency of the welded product, reduce the processing cost of the hairpin motor, and has good practical value and application prospects.

Description

Technical Field

[0001] The present invention belongs to the technical field of welding, and particularly relates to a method for controlling the welding quality of hairpin motor terminals. Background Art

[0002] With the continuous development of China's energy and environmental protection technologies, new energy vehicles have been increasingly applied. In the system composition of new energy vehicles, the motor is the key to the driving of the entire new energy vehicle, and its performance is directly related to the overall power performance of the new energy vehicle.

[0003] Generally, new energy vehicle motors pursue high power, small volume, high torque, and high speed (high power density, high torque density), which is somewhat different from traditional motors. In recent years, the related technologies of new energy vehicle motors have developed rapidly and have begun to shift from traditional round copper wire winding designs to flat copper wire winding (hairpin motor) designs, aiming to utilize the advantages of high slot fill factor, good heat dissipation, and small volume with the same power of flat copper wire motors.

[0004] In the preparation process of hairpin motors, the most important factor affecting their performance lies in the welding forming quality of hairpin motor terminals. On the one hand, due to the complex manufacturing process, high precision requirements, and large production volume of hairpin motors, it is difficult to meet the actual production needs through manual manufacturing; on the other hand, the welding of hairpin motor terminals has very high requirements for the quality of welding forming, and real-time monitoring and control of the welding process are required. Although there have been some improvements in the research on hairpin motor welding devices at home and abroad in recent years, and many related patented technologies have emerged. For example, existing patent documents such as CN 112958929 B, CN113414515 A, CN 113453836 A, etc. have conducted certain research on the welding technology of hairpin motors and have played a certain role in promoting the preparation quality of hairpin motors. However, the existing hairpin motor welding technology is difficult to achieve high-beat and high-efficiency welding of hairpin motor terminals, and it is also difficult to monitor and adjust during the welding process of motor terminals, with poor dynamic adjustment ability, and it is difficult to meet the mass production requirements of hairpin motors efficiently. Summary of the Invention

[0005] In view of one or more of the above defects or improvement requirements in the prior art, the present invention provides a method for controlling the welding quality of hairpin motor terminals, which can realize the state monitoring of each link before, during, and after the welding of hairpin motor terminals, realize the closed-loop quality control of the entire welding process, realize the implementation and regulation of welding process parameters, and thus ensure the welding quality of the terminals.

[0006] To achieve the above object, the present invention provides a method for controlling the welding quality of hairpin motor terminals, which includes the following steps:

[0007] (1) Set up a CCD imaging module to measure the pre-welding planar position of the workpiece and the upper terminal of the workpiece, and determine the scanning welding trajectory of the laser welding system;

[0008] (2) Set up an OCT detection module to measure the three-dimensional morphology of the terminal before welding, determine whether there are defects in the morphology of the terminal, and increase the defocus amount, welding power, and scanning trajectory of the laser welding system when it is determined that there are no defects;

[0009] (3) During welding, use the OCT detection module to measure the keyhole depth and molten pool formation during welding, and adjust the welding process parameters of the laser welding system according to the measurement results, and control the scanning trajectory and scanning speed of the laser welding system;

[0010] (4) After welding is completed, control the OCT detection module to perform terminal morphology detection to determine the forming quality of the hairpin motor terminal.

[0011] As a further improvement of the present invention, in step (1), the positioning method of the workpiece and the upper terminal of the workpiece is a rectangular template matching method, including the following process:

[0012] Use a rectangular template to match the external rectangular contour of the hairpin motor terminal. After obtaining two rectangles, find the symmetric centers P1 and P2 of the two rectangles respectively, then the symmetric center P0 of the scanning welding trajectory of a single hairpin motor terminal is the midpoint of P1 and P2.

[0013] As a further improvement of the present invention, the scanning welding trajectory of a single terminal is rectangular, double-rectangular, elliptical, linear, or infinite; or

[0014] The scanning welding trajectory of a single terminal is a low-frequency elliptical trajectory plus a high-frequency sine trajectory.

[0015] As a further improvement of the present invention, in step (2), the three-dimensional morphology information of the terminal before welding includes the terminal outer dimension and the terminal height; and the process of using the above information to control the process parameters of the laser welding system is as follows:

[0016] Use the three-dimensional morphology information of the terminal before welding to determine the scanning range of a single hairpin motor terminal, and real-time control the defocus amount between the laser welding system and the terminal surface during welding, and the adjustment amount is given by the terminal height information; at the same time, adjust the welding power during welding in real time according to the terminal height information.

[0017] As a further improvement of the present invention, the method for adjusting the welding power of the galvanometer welding system after detecting the real-time keyhole depth is as follows:

[0018] Set the range of the keyhole depth during welding; when the keyhole depth during welding exceeds this range, the increment ΔP of the welding power is obtained by the following formula,

[0019]

[0020] where d is the current keyhole depth; P is the current laser power; d0 is the end value of the keyhole depth range. When d is less than the minimum value of the range, d0 is the minimum value of the range. When d is greater than the maximum value of the range, d0 is the maximum value of the range.

[0021] As a further improvement of the present invention, the measurement of the molten pool forming situation is judged by measuring the width of the molten pool, and the scanning trajectory control during welding is achieved by controlling the high-frequency sine amplitude A, and its value is obtained by the following formula:

[0022]

[0023] where A p is the current amplitude, W p is the ideal molten pool width, and W is the actual molten pool width.

[0024] As a further improvement of the present invention, the welding speed v is correspondingly adjusted according to different welding scanning trajectories, and its value is given by the following formula:

[0025]

[0026] where v p is the default welding speed.

[0027] As long as the above improved technical features do not conflict with each other, they can be combined with each other.

[0028] Generally speaking, compared with the prior art, the beneficial effects of the above technical solutions conceived by the present invention include:

[0029] (1) The method for controlling the welding quality of the hairpin motor terminals of the present invention can realize the state monitoring of each link before, during and after the terminal welding process by using the corresponding settings of the CCD imaging module, OCT detection module and laser welding system, provides a basis for the adjustment of process parameters during the laser welding process of the terminals, realizes the real-time monitoring of each link of the terminal welding process and the dynamic adjustment of the terminal processing process parameters, ensures that the processing of the terminals meets the requirements of actual quality control, improves the yield rate of the hairpin motor processing, and reduces the processing cost of the hairpin motor.

[0030] (2) The method for controlling the welding quality of the hairpin motor terminals of the present invention can quickly and accurately realize the dynamic adjustment of the processing parameters during the welding process of the hairpin motor terminals by preferably setting the determination method of the position of the hairpin motor and its terminals, the determination method of the laser power, and the adjustment method of the scanning trajectory and scanning speed, ensuring the accuracy and reliability of the parameter adjustment.

[0031] (3) The method for controlling the welding quality of the hairpin motor terminals in the present invention has simple steps and convenient control. It can monitor the states of the motor workpiece and the terminals before, during, and after the welding of the hairpin motor terminals, ensuring that the states of the workpiece and the terminals in each link meet the requirements of actual high-quality processing. While realizing the closed-loop control of the welding process, it improves the yield rate and processing efficiency of the welded products, reduces the processing cost of the hairpin motor, and has good practical value and application prospects. Description of the Drawings

[0032] Figure 1 is a schematic flow chart of the method for controlling the welding quality of the hairpin motor terminals in the embodiment of the present invention;

[0033] Figure 2 is a schematic diagram of determining the position of the terminals by using the rectangular template matching method in the embodiment of the present invention;

[0034] Figure 3 is a schematic diagram of the relationship between the laser power and the height of the workpiece surface in the embodiment of the present invention. Detailed Embodiments

[0035] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0036] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "transverse", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0038] In the present invention, unless otherwise clearly specified and defined, terms such as "mounted", "connected", "coupled", "fixed", etc. shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or integrated; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the internal communication of two components or the interaction relationship between two components, unless otherwise clearly defined. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0039] In the present invention, unless otherwise clearly specified and defined, the first feature being "on" or "under" the second feature may be that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "over" and "on top of" the second feature may be that the first feature is directly above or obliquely above the second feature, or merely indicates that the first feature has a higher horizontal height than the second feature. The first feature being "under", "beneath" and "underneath" the second feature may be that the first feature is directly below or obliquely below the second feature, or merely indicates that the first feature has a lower horizontal height than the second feature.

[0040] Embodiment:

[0041] Please refer to Figure 1 , the method for controlling the welding quality of the hairpin motor terminals in the preferred embodiment of the present invention is mainly used to detect and control the welding quality of the terminals during the welding process of the hairpin electronic terminals, and mainly includes the following processes:

[0042] (1) Set up a CCD imaging module, which measures the pre-welding planar position of the workpiece and the terminals on the workpiece, and completes the adjustment of the pre-welding planar coordinate position, so as to determine the scanning welding trajectory of the laser welding system;

[0043] By using the CCD imaging module to locate the position of each hairpin motor terminal, a two-dimensional grayscale image of the motor terminal is taken to determine the planar position coordinates of the terminal.

[0044] In a preferred embodiment, the positioning method for the workpiece and terminals of the hairpin motor to be processed adopts the method of rectangular template matching. Specifically, the external rectangular contour of the hairpin motor terminal is matched with a rectangular template. When performing template matching, it is preferred to allow the actual external contour of the hairpin motor terminal to have rounded corners or notches. In this way, the robustness of the algorithm can be effectively improved. After obtaining two rectangles, the symmetry centers P1 and P2 of the two rectangles are respectively calculated, and the symmetry center P0 of the scanning and welding trajectory of a single hairpin motor terminal is the midpoint of P1 and P2, as Figure 2 shown in

[0045] In actual selection, the scanning and welding trajectory of a single hairpin motor terminal can be rectangular, double-rectangular, elliptical, linear, infinite, etc. In a preferred embodiment, the scanning and welding trajectory is preferably a low-frequency elliptical trajectory plus a high-frequency sine trajectory, and the scanning and welding trajectory in the actual welding process is a combination of the scanning and welding trajectories of each hairpin motor terminal, and the scanning and welding of all terminals on the workpiece of the hairpin motor to be processed are completed in sequence.

[0046] (2) Set up an OCT detection module, use OCT detection technology to measure the three-dimensional morphology of the terminals before welding, and judge whether there are defects in the morphology of the terminals; if there are defects, an alarm is given, and if there are no defects, the defocus amount, welding power and scanning trajectory of the welding system are adjusted according to the measurement results;

[0047] Since the material of the hairpin motor terminal is copper wire, there is often a problem of high reflectivity to laser during the welding process. Therefore, it is necessary to measure the three-dimensional morphology of the hairpin motor terminal to mitigate the problem of high reflectivity existing in the processing from the perspective of process control.

[0048] In a preferred embodiment, the three-dimensional morphology measurement of the hairpin motor terminal is completed by an OCT detection module. The OCT scanning imaging technology is used to quickly scan each terminal of the hairpin motor to obtain the three-dimensional morphology information of each terminal of the hairpin motor, including its external dimensions and height, so as to specifically regulate the welding power and defocus amount of the laser welding system when processing each terminal, and correspondingly adjust the scanning trajectory of the laser welding system when welding the terminals.

[0049] Specifically, the regulation of process parameters is carried out according to the following method:

[0050] By controlling the OCT detection module, the external dimensions and height information of the hairpin motor terminal are obtained to determine the scanning range of a single hairpin motor terminal. Since the surface of the hairpin motor terminal is not all flat, it is necessary to control the defocus amount between the laser welding system and the terminal surface in real time during the welding process, and the amount of adjustment is given by the terminal height information. At the same time, in order to ensure the same penetration depth of the hairpin motor terminal, it is necessary to adjust the laser power in real time during the welding process according to the terminal height information.

[0051] During actual welding, the laser power and the height of the hairpin motor terminal exhibit Figure 3 the relationship shown in min P max and P

[0052] (3) After the welding operation starts, the OCT detection module measures the keyhole depth and the molten pool formation during the welding process;

[0053] After the welding starts, the OCT detection module is used to monitor the keyhole depth of the hairpin motor terminal in real time, avoiding the instability of the welding process caused by environmental factors during the processing. If abnormal fluctuations in the welding penetration or the welding penetration fails to meet the standard are detected, the welding process parameters of the laser welding system are fed back and closed-loop controlled in real time to ensure the forming quality and ensure the consistency and qualified conductivity of the hairpin motor terminal welding. In addition, during actual operation, it is preferably to adjust the welding power and the defocus amount to ensure the welding forming quality of each hairpin motor terminal.

[0054] In the preferred embodiment, the specific regulation process of the welding power is carried out according to the following logic:

[0055] Since the change in the keyhole depth during the welding process is relatively drastic, resulting in the inability to control the keyhole depth fixed at a certain stable value during the welding process, therefore, during actual operation, it is only necessary to ensure that the change in the keyhole depth is within a certain range. If the keyhole depth during the welding process is significantly lower than this interval range, the welding power should be increased in real time, and vice versa.

[0056] Correspondingly, the increment ΔP of the welding power is preferably given by the following formula,

[0057]

[0058] where d is the current keyhole depth; P is the current laser power; d0 is the end point value of the keyhole depth interval range. When d is less than the minimum value of the interval range, d0 is the minimum value of the interval range. When d is greater than the maximum value of the interval range, d0 is the maximum value of the interval range.

[0059] Furthermore, during the welding process, the OCT detection module is controlled to monitor the molten pool shape. Since the size of the molten pool often has a greater impact on the welding forming quality, it is necessary to monitor the molten pool shape during the welding process in real time. If the size of the molten pool fails to meet the welding standard and / or the molten pool shape is strange, it is necessary to feed back and adjust the welding process parameters in real time.

[0060] In a preferred embodiment, it is preferred to ensure the molten pool shape during the welding process by adjusting the scanning trajectory and welding speed of the laser welding system. During actual monitoring, the molten pool monitoring during the welding process mainly monitors the width of the molten pool. The width of the molten pool largely determines the weld width. The scanning trajectory control during the welding process mainly controls its high-frequency sine amplitude A, and its value is given by the following formula:

[0061]

[0062] In the formula, A p is the current amplitude, generally the default value, preferably 2 mm; W p is the ideal molten pool width, and W is the actual molten pool width.

[0063] At the same time, according to the different welding scanning trajectories, different welding speeds v can also be selected, and its value is given by the following formula:

[0064]

[0065] In the formula, v p is the default welding speed.

[0066] (4) After the welding operation is completed, the OCT detection module is used to detect the morphology of the terminal after welding, check the quality of the terminal forming, and judge whether there are defects after the terminal welding process; if it is judged that there are defects, an alarm is given; if no defects are found, the detection process and the terminal welding process are ended.

[0067] During actual operation, the OTC detection module is mainly controlled to measure the formed shape after welding and judge whether there is a situation of missed welding. Among them, for judging whether the terminal shape is qualified, in a preferred embodiment, the surface profile is compared with the ideal profile to determine the forming quality of the terminal. If the maximum value of the difference between the actual profile and the ideal profile exceeds 2 mm, it is determined that the forming is unqualified and operations such as repair welding are required.

[0068] In addition, after all the hairpin motor terminals are welded, it is also preferred that the production management system statistics the yield rate after welding, records the pre-welding morphology information, in-welding welding process parameter information, and post-welding forming morphology information of the terminals with poor welding forming, analyzes the reasons for poor welding forming, so as to optimize the process and welding process parameters, and form a complete closed-loop for the control, detection, and statistics of the whole welding process.

[0069] The method for controlling the welding quality of the hairpin motor terminals in the present invention has simple steps and convenient control. It can monitor the states of the motor workpieces and terminals before, during, and after the welding of the hairpin motor terminals, ensuring that the states of the workpieces and terminals in each link meet the requirements of actual high-quality processing. While realizing the closed-loop control of the welding process, it improves the yield rate and processing efficiency of the welded products, reduces the processing cost of the hairpin motor, and has good practical value and application prospects.

[0070] Those skilled in the art can easily understand that the above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for controlling the welding quality of the terminal of a hairpin motor, characterized in that, The steps are as follows: (1) Set up a CCD imaging module to measure the pre-welding planar positions of the workpiece and the upper terminal of the workpiece, and determine the scanning welding trajectory of the laser welding system. Among them, the positioning method for the workpiece and the upper terminal of the workpiece is the rectangular template matching method, including the following process: Use the rectangular template to match the external rectangular contour of the hairpin motor terminal. After obtaining two rectangles, find the symmetry centers P1 and P2 of the two rectangles respectively. Then, the symmetry center of the scanning welding trajectory of a single hairpin motor terminal is the midpoint P0 of P1 and P2. (2) Set up an OCT detection module to measure the three-dimensional morphology of the terminal before welding, judge whether there are defects in the morphology of the terminal, and increase the defocus amount, welding power and scanning trajectory of the laser welding system when it is judged that there are no defects. Among them, the three-dimensional morphology information of the terminal before welding includes the outer dimension of the terminal and the height of the terminal. And the process of regulating the process parameters of the laser welding system using the above information is as follows: Use the three-dimensional morphology information of the terminal before welding to determine the scanning range of a single hairpin motor terminal, and real-time control the defocus amount between the laser welding system and the terminal surface during the welding process. The amount of adjustment is given by the height information of the terminal. At the same time, the laser power during the welding process is adjusted in real time according to the height information of the terminal. (3) During welding, measure the keyhole depth and the molten pool forming condition during welding through the OCT detection module, and adjust the welding process parameters of the laser welding system according to the measurement results, and regulate the scanning trajectory and scanning speed of the laser welding system. (4) After welding is completed, control the OCT detection module to perform terminal morphology detection to judge the forming quality of the hairpin motor terminal.

2. The method for controlling the welding quality of the terminal of a hairpin motor according to claim 1, characterized in that, The scanning welding trajectory of a single terminal is rectangular, double-rectangular, elliptical, linear or infinite; or The scanning welding trajectory of a single terminal is a low-frequency elliptical trajectory plus a high-frequency sine trajectory.

3. The method for controlling the welding quality of the terminal of a hairpin motor according to claim 1, characterized in that, In step (3), after detecting the real-time keyhole depth, the method for adjusting the welding power of the laser welding system is as follows: Set the range of the keyhole depth during welding; when the keyhole depth during welding exceeds this range, the increment ∆ of its welding power is obtained by the following formula P as follows Wherein, is the current keyhole depth; is the current laser power; 0 are the endpoint values of the keyhole depth interval range. When d is less than the minimum value of the interval range, d 0 is the minimum value of the interval range. When d is greater than the maximum value of the interval range, d 0 is the maximum value of the interval range.

4. The method for controlling the welding quality of the terminal of a hairpin motor according to any one of claims 1 to 3, characterized in that, The measurement of the molten pool forming situation is judged by measuring the width of the molten pool, and the scanning trajectory regulation during the welding process is achieved by controlling the high-frequency sine amplitude A which is obtained by the following formula: In the formula, is the current amplitude, is the ideal weld pool width, W is the actual weld pool width.

5. The method for controlling the welding quality of the terminal of a hairpin motor according to claim 4, characterized in that, Adjust the welding speed accordingly according to different welding scanning trajectories , and its value is given by the following formula: In the formula, is the default welding speed.

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