Motor commutator and winding joint welding method and motor

Abstract

The invention relates to the technical field of motor welding, in particular to a welding method of a motor commutator and a winding connector and a motor, a double-area welding connector is used, and double areas comprise a central area and an edge area surrounding the outer side of the central area; the welding method comprises the following steps: determining a heat conductivity coefficient threshold value and a thermal expansion coefficient threshold value of the commutator segment according to a material of the commutator segment; detecting a heat conductivity coefficient and a thermal expansion coefficient of the commutator segment, and setting a temperature difference between the central region and the edge region according to a detection result; independently controlling the heating power of the central area and the edge area, so that the temperature difference is formed between the central area and the edge area; and the double-zone welding head executes the temperature difference welding of the commutator and the winding joint. According to the welding method and the motor, the temperature difference between the central area and the edge area of the double-area welding head is dynamically adjusted through zoned temperature control of the double-area welding head in combination with the heat conductivity coefficient and the thermal expansion coefficient of a commutator segment material, and the performance and reliability of a motor commutation system are remarkably improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor welding, and in particular to a method for welding a motor commutator and a winding joint, and a motor. Background Art

[0002] In motor manufacturing, the welding process for commutators and winding joints is a critical step in affecting motor performance and reliability. Traditionally, spot welding with a resistance welder is used. Due to differences in thermal conductivity and thermal expansion properties between commutator segment materials (such as copper, copper alloys, or silver-copper composites), or between batches of the same material, the uniform heating of the entire joint by a resistance welder can easily lead to unstable weld quality and even cause problems such as cold joints, cracked solder joints, and concentrated thermal stress.

[0003] To address thermal stress, some existing solutions use preheating or gradient heating. However, these methods fail to consider the material properties of the commutator segments. For example, commutator segments with high thermal conductivity dissipate heat quickly, leading to uneven temperature distribution in the weld zone. Materials with high thermal expansion coefficients can contract unevenly after cooling, causing deformation or microcracks in the weld joints. Furthermore, improperly controlled welding temperatures can damage the winding insulation or the commutator surface structure, reducing the motor's electrical performance and mechanical strength. Summary of the Invention

[0004] To this end, the purpose of the present invention is to overcome the welding quality problems including thermal stress concentration, weld strength and weld cracks caused by not considering the material properties of the commutator segments in the prior art, and to provide a welding method and a motor for a motor commutator and a winding joint. By controlling the temperature of the dual-zone welding head in different zones and dynamically adjusting the temperature difference between the center zone and the edge zone of the dual-zone welding head in combination with the thermal conductivity and thermal expansion coefficient of the commutator segment material, the problem of unstable weld quality caused by differences in the thermal properties of the commutator segment material is effectively solved, and the performance and reliability of the motor commutation system are significantly improved.

[0005] In a first aspect, to solve the above technical problems, the present invention provides a method for welding a motor commutator and a winding joint, using a dual-zone welding head, wherein the dual zones include a central zone and an edge zone surrounding the central zone; the welding method comprises: Determining a thermal conductivity threshold and a thermal expansion coefficient threshold of the commutator segment according to the material of the commutator segment; detecting the thermal conductivity and thermal expansion coefficient of the commutator segment, and setting the temperature difference between the central area and the edge area according to the detection results; independently controlling the heating power of the central area and the edge area so that the temperature difference is formed between the central area and the edge area; The dual-zone welding head performs the temperature difference welding of the commutator and the winding joint; Among them, if the thermal conductivity is greater than the thermal conductivity threshold and the thermal expansion coefficient is greater than the thermal expansion coefficient threshold, the temperature difference is set to 8~12°C; if the thermal conductivity is less than or equal to the thermal conductivity threshold, or the thermal expansion coefficient is less than or equal to the thermal expansion coefficient threshold, the temperature difference is set to 18~22°C.

[0006] In one embodiment of the present invention, setting the temperature difference further includes, if the thermal conductivity is greater than a thermal conductivity threshold and the thermal expansion coefficient is less than or equal to a thermal expansion coefficient threshold, setting the temperature difference to 14-18° C.

[0007] In one embodiment of the present invention, independently controlling the heating power of the central area and the edge area includes: determining the base temperature of the central area and the edge area respectively according to the thermal conductivity and thermal expansion coefficient of the commutator segment; independently controlling the heating power of the central area and the edge area to heat to the base temperature; detecting the temperature of the central area and the edge area and calculating the temperature difference therebetween, comparing the detected temperature difference with the set temperature difference, if the detected temperature difference is less than the set temperature difference, increasing the heating power of the central area so that the detected temperature difference is consistent with the set temperature difference; if the detected temperature difference is greater than the set temperature difference, reducing the heating power of the central area so that the detected temperature difference is consistent with the set temperature difference.

[0008] In one embodiment of the present invention, independently controlling the heating power of the central area and the edge area also includes monitoring the temperature distribution of the welding area by infrared thermal imaging, and determining whether there are layout hot spots and local cold spots based on the temperature distribution; if it is determined that there are local hot spots, when the detected temperature difference is greater than the set temperature difference, reducing the heating power of the central area while increasing the heating power of the edge area, so that the detected temperature difference is consistent with the set temperature difference; if it is determined that there are local cold spots, when the detected temperature difference is less than the set temperature difference, increasing the heating power of the central area while reducing the heating power of the edge area, so that the detected temperature difference is consistent with the set temperature difference.

[0009] In one embodiment of the present invention, a commutator segment material-thermal parameter threshold mapping table is pre-established, and the thermal conductivity threshold and thermal expansion coefficient threshold corresponding to the current commutator segment material are determined based on the mapping table.

[0010] In one embodiment of the present invention, the dual-zone welding head includes a first tungsten rod heating module configured corresponding to the central zone and a second tungsten rod heating module configured corresponding to the edge zone, and an aluminum nitride ceramic isolation layer arranged between the first tungsten rod heating module and the second tungsten rod heating module; wherein, the first tungsten rod heating module is configured as a cylindrical structure, the center of which corresponds to the geometric center of the target welding area.

[0011] In one embodiment of the present invention, the difference between the heating power density of the first tungsten rod heating module and the heating power density of the second tungsten rod heating module is 28W / cm 2 ~35W / cm 2 .

[0012] In one embodiment of the present invention, the welding method further includes detecting the resistivity between the commutator and the winding joint, and adjusting the temperature difference according to the detected resistivity, which includes calculating the difference between the detected resistivity and the target resistivity; introducing a temperature adjustment coefficient λ; and adjusting the temperature difference according to the difference and the temperature adjustment coefficient; The adjustment formula is: ; ΔT represents the adjusted temperature difference; ΔT0 represents the set temperature difference; λ represents the temperature adjustment coefficient, which ranges from 0.5 to 1.0; Indicates the detection resistivity; Indicates the target resistivity.

[0013] In one embodiment of the present invention, the welding method further includes adjusting welding parameters according to the difference D between the detected resistivity and the target resistivity, which includes: if the difference D is greater than 0, reducing the welding speed (to suppress grain coarsening); if the difference D is less than 0, increasing the shielding gas flow rate (to prevent oxidation).

[0014] In a second aspect, in order to solve the above technical problems, the present invention further provides a motor, comprising a commutator and a winding, and welding the joints of the commutator and the winding according to the welding method of the motor commutator and the winding joints.

[0015] The above technical solution of the present invention has the following beneficial effects compared with the prior art: The welding method for the motor commutator and winding joint and the motor described in the present invention control the temperature of the dual-zone welding joint by zone, and dynamically adjust the temperature difference between the central area and the edge area of ​​the dual-zone welding joint in combination with the thermal conductivity and thermal expansion coefficient of the commutator material, effectively solving the problem of unstable solder joint quality caused by differences in the thermal characteristics of the commutator material, and significantly improving the performance and reliability of the motor commutation system. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to make the contents of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments of the present invention in conjunction with the accompanying drawings.

[0017] Figure 1 Flowchart of a method for welding a motor commutator and a winding joint in a preferred embodiment of the present invention; Figure 2 Schematic diagram of the structure of a dual-zone welding head in a preferred embodiment of the present invention; Figure 3 Flowchart of a method for welding a motor commutator and a winding joint according to another embodiment of the present invention; Figure 4 This is a flow chart of independently controlling the heating power of the central area and the edge area in a preferred embodiment of the present invention; Figure 5 This is a flow chart of adjusting the temperature difference according to the detected resistivity in a preferred embodiment of the present invention.

[0018] In the figure, 10 is a first tungsten rod heating module; 20 is a second tungsten rod heating module; 30 is an aluminum nitride ceramic isolation layer. DETAILED DESCRIPTION

[0019] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0020] The purpose of the embodiments of the present invention is to solve the welding quality problems including thermal stress concentration, weld strength and weld cracks caused by the use of preheating or gradient heating methods during the welding process of the motor commutator and the winding joint without considering the material properties of the commutator segments in the prior art.

[0021] The commutator is a core component of a DC motor (such as a brushed motor). It is fixed to the motor rotor and slides in contact with the brushes to transmit current. Its primary function is to automatically switch the direction of the current in the armature winding during motor rotation, thereby maintaining continuous operation. The commutator consists of multiple segments, typically made of highly conductive and wear-resistant electrolytic copper or copper alloys (such as silver-copper or cadmium-copper). These segments are formed through precision stamping, turning, or powder metallurgy processes and then welded to the armature winding's winding joints.

[0022] Example 1: Reference Figure 1 As shown, an embodiment of the present invention discloses a method for welding a motor commutator and a winding joint, using a dual-zone welding head, wherein the dual zones include a central zone and an edge zone surrounding the central zone; the welding method includes: S10, determining a thermal conductivity threshold value and a thermal expansion coefficient threshold value of the commutator segment according to the material of the commutator segment; S20, detecting the thermal conductivity and thermal expansion coefficient of the commutator segment, and setting the temperature difference between the central area and the edge area according to the detection results; S30, independently controlling the heating power of the central area and the edge area so that the temperature difference is formed between the central area and the edge area; S40, the dual-zone welding head performs the temperature difference welding of the commutator and the winding joint; Among them, if the thermal conductivity is greater than the thermal conductivity threshold and the thermal expansion coefficient is greater than the thermal expansion coefficient threshold, the temperature difference is set to 8~12°C; if the thermal conductivity is less than or equal to the thermal conductivity threshold, or the thermal expansion coefficient is less than or equal to the thermal expansion coefficient threshold, the temperature difference is set to 18~22°C.

[0023] In a specific application scenario, the welding method of the present invention is implemented by spot welding the motor commutator and the winding joint with the help of a resistance welding machine. Spot welding is to achieve a slight metal fusion between the welded parts (the welded parts are a general term for copper hooks, enameled wires, and commutator segments) by heating with resistance and coordinating with hot pressing. The welding head used in the resistance welding machine in the embodiment of the present invention is a dual-zone welding head, which includes a central area and an edge area surrounding the outer side of the central area. The central area and the edge area are independently temperature-controlled by independently controlling the heating power. It should be noted here that the central area of ​​the dual-zone welding head is located at the geometric center of the welding head and directly acts on the central connection part of the weld (such as the overlapping area of ​​the commutator copper hook and the winding). The central area provides high energy density heating to ensure that the central connection part of the weld quickly reaches the melting temperature (such as the melting point of copper material is greater than or equal to 1083°C) to form a main fusion zone. The edge zone surrounds the outside of the central zone, covering the edge connection parts of the weldment (such as the overlap area between the winding and the commutator segment), providing low-energy density auxiliary heating, controlling the temperature of the edge area of ​​the weldment, and preventing local overheating from causing thermal stress concentration or porosity defects in the material.

[0024] Specifically, refer to Figure 2 As shown, the dual-zone welding head includes a first tungsten rod heating module 10 corresponding to the central zone and a second tungsten rod heating module 20 corresponding to the edge zone, along with an aluminum nitride ceramic isolation layer 30 disposed between the first and second tungsten rod heating modules. The first tungsten rod heating module 10 is cylindrical, with its center corresponding to the geometric center of the welding zone. The tungsten rod diameter of the first tungsten rod heating module 10 ranges from 8 to 12 mm, preferably 10 mm, to ensure sufficient heating power density. The rod length is set based on the size of the welding zone, typically 20 to 50 mm, and is coated with a 5-10 μm iridium layer to enhance high-temperature oxidation resistance. The second tungsten rod heating module 20 surrounds the central zone, forming a ring-shaped heating zone and is evenly spaced from the central zone. The inner diameter of the tungsten rod ring is 5-10 mm larger than the outer diameter of the welding zone, and the outer diameter is set to suit the equipment space. Each of the first and second tungsten rod heating modules 10 and 20 is equipped with a PID controller for independent heating power control and temperature control. The aluminum nitride ceramic isolation layer 30 blocks more than 80% of the heat radiation in the center area, reducing the risk of overheating in the edge area. Its surface polishing improves the infrared reflection efficiency and reduces heating energy consumption.

[0025] Furthermore, the heating power density of the first tungsten rod heating module 10 is greater than the heating power density of the second tungsten rod heating module 20. The high power density in the central area quickly heats up to the set temperature, and the low power density in the edge area maintains the temperature, thereby reducing the overall heating energy consumption. The difference between the heating power density of the first tungsten rod heating module 10 and the heating power density of the second tungsten rod heating module 20 is 28W / cm 2 ~35W / cm 2 By setting the difference between the heating power density of the first tungsten rod heating module and the heating power density of the second tungsten rod heating module to 28W / cm 2 ~35W / cm 2 , can precisely control the temperature difference between the center and edge areas, high power density difference (35W / cm 2 ) is suitable for low thermal conductivity materials, requiring a large temperature difference to ensure fusion; low power density difference (28W / cm 2 ) is suitable for high thermal conductivity materials, requiring a smaller temperature difference to prevent overheating. Setting the heating power density difference reduces heating power by 15% to 20%. Optimizing the heating power density difference also reduces temperature fluctuations between the center and edge areas.

[0026] During the welding initialization phase, a database covering the characteristics of various commutator segment materials is established. This database records in detail the typical value ranges of the thermal conductivity and thermal expansion coefficient of commutator segments of different materials. Based on experimental data and actual production experience, corresponding thermal conductivity thresholds and thermal expansion coefficient thresholds are set for each material commutator segment, and a material-thermal parameter threshold mapping table for the commutator segment is established. For common copper-based alloy commutator segments, such as Cu-Ag alloys with different silver contents, the difference in silver content will significantly affect the thermal conductivity and thermal expansion properties of the material. Generally speaking, the higher the silver content, the higher the thermal conductivity, and the thermal expansion coefficient will also vary within a certain range. For example, a Cu-Ag alloy with a silver content of 60% may have a thermal conductivity of 380-400W / (m·K) and a thermal expansion coefficient of approximately 18-19×10 -6 / ℃, through multiple welding tests under different process conditions and combined with the welding quality evaluation results, it can be determined that the thermal conductivity threshold of the material is 390W / (m·K) and the thermal expansion coefficient threshold is 18.5×10 -6 / ℃.

[0027] Before welding begins, the material composition of the commutator segment is identified, and the thermal conductivity threshold value and thermal expansion coefficient threshold value corresponding to the current material of the commutator segment are determined according to a pre-established mapping table.

[0028] The thermal conductivity and thermal expansion coefficient of the commutator segments that need to be welded are tested. Both can be determined using existing methods. For example, a laser flash thermal conductivity analyzer is used to test the thermal conductivity. A laser pulse is used to instantaneously heat the front of the sample, and an infrared detector is used to measure the temperature change over time on the back of the sample. Based on thermal diffusion theory, the thermal diffusivity of the material is calculated from the temperature change curve. The thermal conductivity is then calculated by combining the material's density and specific heat capacity. The thermal expansion coefficient is measured using a thermomechanical analyzer. At a controlled temperature, the dimensional change of the sample under stress is measured. The thermal expansion coefficient of the material is calculated by recording the curve of the sample's length change with temperature.

[0029] After determining the thermal conductivity and thermal expansion coefficient of the commutator segment, the temperature difference between the center and edge zones of the dual-zone weld joint is matched according to the set rules: if the thermal conductivity is greater than the thermal conductivity threshold and the thermal expansion coefficient is greater than the thermal expansion coefficient threshold, it indicates that the material has fast thermal conductivity and significant thermal expansion. High thermal conductivity leads to rapid heat conduction, and high expansion easily causes thermal stress concentration. To avoid overheating during welding, which may lead to deterioration of solder joint quality and material deformation, the temperature difference between the center and edge zones is set to 8-12°C. For example, for a Cu-Ag alloy commutator segment with a high silver content and strong thermal conductivity and thermal expansion properties, if the actual measured thermal conductivity is 400W / (m·K) and the thermal expansion coefficient is 19×10 -6 / °C, both greater than the threshold, the temperature difference between the center and edge zones is set to 10°C. If the thermal conductivity is less than or equal to the thermal conductivity threshold, or the thermal expansion coefficient is less than or equal to the thermal expansion threshold, this indicates that the material conducts heat relatively slowly or has insignificant thermal expansion. To ensure sufficient heat in the weld zone for fusion, a larger temperature difference is required, ranging from 18-22°C. For example, for an Fe-Si alloy commutator segment, if the actual measured thermal conductivity is 90 W / (m·K), which is less than the set threshold of 100 W / (m·K), the temperature difference between the center and edge zones is set to 20°C. By accurately identifying the material properties of the commutator segment and matching the corresponding temperature difference between the center and edge zones, welding defects caused by improper temperature control can be effectively avoided. For materials with large thermal conductivity and thermal expansion coefficients, a smaller temperature difference can reduce overheating, prevent problems such as burnout and deformation of the solder joint, and improve the density and bond strength of the solder joint. For materials with low thermal conductivity or thermal expansion coefficient, a larger temperature difference can ensure sufficient heat input, allowing the welding area to fully fuse, avoiding defects such as false welds and cold welds, thereby significantly improving the stability of welding quality and increasing the welding qualification rate from about 85% of traditional processes to more than 98%.

[0030] After determining the temperature difference between the central area and the edge area of ​​the dual-zone welding head, the heating power of the central area and the edge area is independently controlled so that the temperature difference is formed between the central area and the edge area. When the temperature difference between the central area and the edge area of ​​the dual-zone welding head reaches the set temperature difference, the welding commutator and the winding joint are started. During welding, the center of the central area of ​​the dual-zone welding head coincides with the geometric center of the welding area.

[0031] The welding method for the motor commutator and the winding joint described in the present invention controls the temperature of the dual-zone welding joint by zone, and dynamically adjusts the temperature difference between the center zone and the edge zone of the dual-zone welding joint in combination with the thermal conductivity and thermal expansion coefficient of the commutator material, effectively solving the problem of unstable solder joint quality caused by differences in the thermal characteristics of the commutator material, and significantly improving the performance and reliability of the motor commutation system.

[0032] As another embodiment of the present invention, refer to Figure 3 As shown, setting the temperature difference also includes, if the thermal conductivity is greater than a thermal conductivity threshold and the thermal expansion coefficient is less than or equal to a thermal expansion coefficient threshold, setting the temperature difference to 14-18°C.

[0033] In a specific application scenario, if the thermal conductivity is greater than the thermal conductivity threshold and the thermal expansion coefficient is less than or equal to the thermal expansion coefficient threshold, it indicates that the commutator segment has fast thermal conductivity and small thermal expansion, heat can be quickly conducted inside the material, and the heat generated during the welding process will not be excessively concentrated near the welding area; and the dimensional changes of the commutator segment are relatively stable when the temperature changes.

[0034] It should be noted that although the case where the thermal conductivity is greater than the thermal conductivity threshold and the thermal expansion coefficient is less than or equal to the thermal expansion coefficient threshold belongs to the subset of the thermal expansion coefficient less than or equal to the thermal expansion coefficient threshold, more precise control is required in the actual process. Even if the thermal expansion coefficient is low, the high thermal conductivity and its rapid heat transfer characteristics will cause the heat in the center area to easily diffuse to the edge area. The edge area is prone to overheating and cause oxidation of the solder joint surface. Compared with the case where the thermal expansion coefficient is less than or equal to the thermal expansion coefficient threshold, the temperature difference needs to be reduced to inhibit heat conduction, so the temperature difference is set to 14~18℃, which can not only ensure that the welding area has sufficient heat for fusion, but also avoid defects in the edge area due to overheating.

[0035] Further, refer to Figure 4As shown, independently controlling the heating power of the central area and the edge area includes, respectively determining the base temperature of the central area and the edge area according to the thermal conductivity and thermal expansion coefficient of the commutator segment; independently controlling the heating power of the central area and the edge area to heat to the base temperature; detecting the temperature of the central area and the edge area and calculating the temperature difference therebetween, comparing the detected temperature difference with the set temperature difference, if the detected temperature difference is less than the set temperature difference, increasing the heating power of the central area so that the detected temperature difference is consistent with the set temperature difference; if the detected temperature difference is greater than the set temperature difference, reducing the heating power of the central area so that the detected temperature difference is consistent with the set temperature difference.

[0036] In specific application scenarios, a database is established based on experimental data and actual production experience data. The database stores the welding temperatures of welding joints corresponding to the thermal conductivity and thermal expansion coefficients of various materials, including the basic temperatures of the center and edge zones. It is equivalent to a work manual for the welding joint, corresponding to commutator segments of different materials, or corresponding to different thermal conductivity and different thermal expansion coefficients of the same material. Basic temperatures are matched to guide welding production. After detecting the thermal conductivity and thermal expansion coefficient of the current commutator segment, the base temperature of the center zone and the base temperature of the edge zone of the dual-zone welding joint are matched from the database. For example, for copper-based alloy commutator segments, different silver contents correspond to different thermal conductivity and thermal expansion coefficients, as well as the corresponding base temperature of the center zone and the base temperature of the edge zone of the dual-zone joint. The heating power of the dual-zone welding joint is controlled by the base temperature. During the heating process of the dual-zone welding joint to reach the base temperature, the temperature sensor built into the dual-zone welding joint detects the temperature of the center zone and the edge zone until their respective base temperatures are reached. Then, the temperature difference between the center area and the edge area is calculated, and this temperature difference is set as the detection temperature difference. The detection temperature difference is compared with the set temperature difference. If the detection temperature difference is less than the set temperature difference, the heating power of the center area is increased so that the detection temperature difference is consistent with the set temperature difference; if the detection temperature difference is greater than the set temperature difference, the heating power of the center area is reduced so that the detection temperature difference is consistent with the set temperature difference. The purpose of increasing the heating power of the center area is to increase the temperature of the center area of ​​the dual-zone welding head. By increasing the heating power of the center area while keeping the heating power of the edge area unchanged, the temperature difference between the center area and the edge area is increased. The center area directly heats the weld, which heats up faster and avoids overheating of the edge area and causing thermal stress concentration. The purpose of reducing the heating power of the center area is to reduce the temperature of the center area of ​​the dual-zone welding head. By reducing the heating power of the center area while keeping the heating power of the edge area unchanged, the temperature difference between the center area and the edge area is reduced. Reducing the temperature of the center area can reduce the overall heat input and reduce the risk of overheating in the edge area.

[0037] Furthermore, on the basis of the above scheme, independently controlling the heating power of the central area and the edge area also includes monitoring the temperature distribution of the welding area by infrared thermal imaging, and determining whether there are layout hot spots and local cold spots based on the temperature distribution; if it is determined that there is a local hot spot, when the detected temperature difference is greater than the set temperature difference, reducing the heating power of the central area while increasing the heating power of the edge area, so that the detected temperature difference is consistent with the set temperature difference; if it is determined that there is a local cold spot, when the detected temperature difference is less than the set temperature difference, increasing the heating power of the central area while reducing the heating power of the edge area, so that the detected temperature difference is consistent with the set temperature difference.

[0038] In specific application scenarios, infrared thermal imaging is used to monitor the temperature distribution in the welding area of ​​the weldment to determine whether there are local hot spots or local cold spots. The local hot spot here is defined as a temperature point where the actual temperature exceeds the expected temperature by 15°C or more, indicating that the temperature in this area is significantly higher than the surrounding area; the local cold spot is defined as a temperature point where the actual temperature is lower than the expected temperature by 15°C or more, indicating that the temperature in this area is significantly lower than the surrounding area.

[0039] If a local hot spot is determined to exist, and the detected temperature difference is greater than the set temperature difference, the heating power of the center zone is reduced while the heating power of the edge zone is increased, so that the detected temperature difference is consistent with the set temperature difference. If a local cold spot is determined to exist, and the detected temperature difference is less than the set temperature difference, the heating power of the center zone is increased while the heating power of the edge zone is reduced, so that the detected temperature difference is consistent with the set temperature difference. In other words, in the extreme case where there are no local hot spots or local cold spots, the strategy for adjusting the temperature difference between the center and edge zones of the dual-zone welding head is only to change the heating power of the center zone, while the heating power of the edge zone remains unchanged. When and only when the extreme case occurs (the presence of a local hot spot or a local cold spot), the heating power of the center zone and the heating power of the edge zone are adjusted synchronously to quickly eliminate local defects and reduce the risk of thermal stress concentration in the edge zone.

[0040] In a further embodiment of the present invention, the welding method further includes detecting the resistivity between the commutator and the winding joint, and adjusting the temperature difference according to the detected resistivity, which includes calculating the difference between the detected resistivity and the target resistivity; introducing a temperature adjustment coefficient λ; and adjusting the temperature difference according to the difference and the temperature adjustment coefficient; The adjustment formula is: ; ΔT represents the adjusted temperature difference; ΔT0 represents the set temperature difference; λ represents the temperature adjustment coefficient, which ranges from 0.5 to 1.0; Indicates the detection resistivity; Indicates the target resistivity.

[0041] In specific application scenarios, the resistivity of the weld joint is measured and compared with the target resistivity to determine the adjustment direction. The target resistivity is determined based on the motor's performance requirements. If the measured resistivity is greater than the target resistivity, the weld is highly conductive, and the temperature difference is reduced to improve weld strength. If the measured resistivity is less than the target resistivity, the weld is less conductive, and the temperature difference is increased to ensure sufficient heat for fusion and reduce lack of fusion defects. The temperature difference is automatically adjusted based on resistivity changes to meet the welding quality consistency requirements of different batches of materials.

[0042] In the embodiment of the present invention, not only is the temperature difference of the dual-zone welding head adjusted according to the material properties of the commutator segment, but the temperature difference is also corrected in combination with the welding quality feedback of the weldment, forming a two-level control of positive adjustment and reverse feedback, further improving the welding quality and consistency.

[0043] Furthermore, the welding method also includes adjusting welding parameters according to the difference D between the detected resistivity and the target resistivity, which includes: if the difference D is greater than 0, reducing the welding speed; if the difference D is less than 0, increasing the shielding gas flow rate.

[0044] In specific application scenarios, if the difference D is greater than 0, the detected resistivity is higher than the target resistivity. Since a higher resistivity means the weldment generates relatively more heat during the welding process, if the welding speed is too fast, the heat will not have enough time to be fully conducted and dissipated, which can easily lead to grain coarsening. By reducing the welding speed, the heat can have sufficient time to diffuse, thereby inhibiting grain coarsening and ensuring the microstructure and performance of the solder joint. Conversely, if the difference D is less than 0, the detected resistivity is lower than the target resistivity. Low-resistivity weldments are more likely to react with oxygen in the air during welding, leading to solder joint oxidation. By increasing the shielding gas flow rate to form a thicker shielding gas layer, the air is effectively isolated, preventing solder joint oxidation and improving solder joint quality and reliability.

[0045] Example 2: Based on the same inventive concept, an embodiment of the present invention provides a motor, including a commutator and a winding, and the joint between the commutator and the winding is welded according to the welding method of the motor commutator and the winding joint described in Example 1.

[0046] The embodiment of the present invention has the same inventive concept as the first embodiment, and both have the same technical effects, which will not be described in detail here.

[0047] In summary, the welding method for the motor commutator and the winding joint and the motor described in the present invention, through the zoned temperature control of the dual-zone welding head, and combined with the thermal conductivity and thermal expansion coefficient of the commutator material to dynamically adjust the temperature difference between the center and edge areas of the welding head, effectively solve the unstable solder joint quality caused by differences in the thermal properties of the materials, and significantly improve the performance and reliability of the motor commutation system.

[0048] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for welding a motor commutator and a winding joint, characterized in that: Using a dual-zone welding head, the dual zones include a central zone and an edge zone surrounding the central zone; the welding method includes, Determining a thermal conductivity threshold and a thermal expansion coefficient threshold of the commutator segment according to the material of the commutator segment; detecting the thermal conductivity and thermal expansion coefficient of the commutator segment, and setting the temperature difference between the central area and the edge area according to the detection results; independently controlling the heating power of the central area and the edge area so that the temperature difference is formed between the central area and the edge area; The dual-zone welding head performs the temperature difference welding of the commutator and the winding joint; Among them, if the thermal conductivity is greater than the thermal conductivity threshold and the thermal expansion coefficient is greater than the thermal expansion coefficient threshold, the temperature difference is set to 8~12°C; if the thermal conductivity is less than or equal to the thermal conductivity threshold, or the thermal expansion coefficient is less than or equal to the thermal expansion coefficient threshold, the temperature difference is set to 18~22°C.

2. The method for welding a motor commutator and a winding joint according to claim 1, characterized in that: Setting the temperature difference further includes, if the thermal conductivity is greater than a thermal conductivity threshold and the thermal expansion coefficient is less than or equal to a thermal expansion coefficient threshold, setting the temperature difference to 14-18°C.

3. The method for welding a motor commutator and a winding joint according to claim 1 or 2, characterized in that: Independently controlling the heating power of the central zone and the edge zone includes, Determining the base temperatures of the central area and the edge area respectively according to the thermal conductivity and thermal expansion coefficient of the commutator segment; independently controlling the heating power of the central zone and the edge zone to heat to the base temperature; The temperatures of the central area and the edge area are detected and the temperature difference between the two is calculated, and the detected temperature difference is compared with the set temperature difference. If the detected temperature difference is less than the set temperature difference, the heating power of the central area is increased so that the detected temperature difference is consistent with the set temperature difference; if the detected temperature difference is greater than the set temperature difference, the heating power of the central area is reduced so that the detected temperature difference is consistent with the set temperature difference.

4. The method for welding a motor commutator and a winding joint according to claim 3, characterized in that: Independently controlling the heating power of the central zone and the edge zone, further comprising, Monitor the temperature distribution of the welding area by infrared thermal imaging, and determine whether there are hot spots and local cold spots based on the temperature distribution; If it is determined that there is a local hot spot, when the detected temperature difference is greater than the set temperature difference, the heating power of the central area is reduced while the heating power of the edge area is increased so that the detected temperature difference is consistent with the set temperature difference; If it is determined that there is a local cold spot, when the detected temperature difference is less than the set temperature difference, the heating power of the central area is increased while the heating power of the edge area is reduced so that the detected temperature difference is consistent with the set temperature difference.

5. The method for welding a motor commutator and a winding joint according to claim 1, characterized in that: A material-thermal parameter threshold mapping table of the commutator segment is pre-established, and the thermal conductivity threshold and thermal expansion coefficient threshold corresponding to the current material of the commutator segment are searched and determined according to the mapping table.

6. The method for welding a motor commutator and a winding joint according to claim 1, characterized in that: The dual-zone welding head includes a first tungsten rod heating module configured corresponding to the central zone and a second tungsten rod heating module configured corresponding to the edge zone, and an aluminum nitride ceramic isolation layer arranged between the first tungsten rod heating module and the second tungsten rod heating module; wherein, the first tungsten rod heating module is configured as a cylindrical structure, and its center corresponds to the geometric center of the target welding area.

7. The method for welding a motor commutator and a winding joint according to claim 6, characterized in that: The difference between the heating power density of the first tungsten rod heating module and the heating power density of the second tungsten rod heating module is 28W / cm 2 ~35W / cm 2 .

8. The method for welding a motor commutator and a winding joint according to claim 1, characterized in that: The welding method further includes detecting the resistivity between the commutator and the winding joint, and adjusting the temperature difference according to the detected resistivity, which includes, Calculate the difference between the detected resistivity and the target resistivity; Introducing temperature adjustment coefficient λ; adjusting the temperature difference according to the difference and a temperature adjustment coefficient; The adjustment formula is: ； ΔT represents the adjusted temperature difference; ΔT0 represents the set temperature difference; λ represents the temperature adjustment coefficient, which is 0.5~1.0; Indicates the detection resistivity; Indicates the target resistivity.

9. The method for welding a motor commutator and a winding joint according to claim 8, characterized in that: The welding method further includes adjusting welding parameters according to the difference D between the detected resistivity and the target resistivity, which includes: if the difference D is greater than 0, reducing the welding speed; if the difference D is less than 0, increasing the shielding gas flow rate.

10. A motor including a commutator and windings, characterized in that: The method for welding a motor commutator and a winding joint according to any one of claims 1 to 9 is used to weld the joint between the commutator and the winding.

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