A hairpin flat copper wire armature welding method

Abstract

A hairpin flat copper wire armature welding method comprises the following steps: step 1, using visual inspection equipment to detect foreign matter and oxidation spots on the outer surface of the copper wire of the product to be welded extending out of the welding tooling part, and dividing the foreign matter and oxidation spots into percentage grades; step 2, spraying flux according to the visual inspection result of step 1; step 3, preheating the copper wire welding point, and the preheating temperature is selected according to the visual inspection result of step 1; step 4, using wave soldering equipment for welding, and the soldering temperature, welding time, and nitrogen pressure are selected according to the visual inspection result of step 1; step 5, using a welding quality inspection system to inspect the welding point. The hairpin flat copper wire armature welding method of the present invention has a simple production process, is easy to implement, is easy to operate, and has low equipment investment. With simple equipment investment, efficient and stable welding connection of armature flat copper wire can be achieved.

Description

Technical Field

[0001] The invention relates to the field of machinery, and in particular to a method and application of welding the ends of a permanent magnet or asynchronous motor armature using a flat copper wire material, and in particular to a hairpin flat copper wire armature welding method. Background Art

[0002] With the rapid development of electric vehicle technology, motor stators have begun to be manufactured using flat copper wire. However, due to the large cross-sectional area of ​​flat copper wire, it is difficult to form the wire, so the armature of the stator needs to use welding technology during the manufacturing process. There are currently two commonly used welding processes, namely argon arc welding and laser welding. In the prior art, the argon arc welding temperature is relatively high, the thermal conductivity of the flat copper wire is relatively good, and the insulation layer of the flat copper wire is easily affected by temperature. The investment cost of laser welding equipment is relatively high. In addition, the maximum heating temperature of the motor stator during operation is usually no more than 200°C, and considering factors such as vibration, the solder paste material is required to be able to withstand a high temperature of at least 250°C, making welding a key technical problem in motor manufacturing.

[0003] In addition, the stator has many points that need to be welded during the manufacturing process. The normal number of welding points is about 100, and the maximum number of welding points is nearly 200. How to invest low cost and weld efficiently, quickly and stably is a difficulty. Summary of the invention

[0004] The purpose of the present invention is to provide a hairpin flat copper wire armature welding method, which aims to solve the technical problem of how to achieve low-cost investment and efficient, fast and stable welding in the prior art.

[0005] A hairpin flat copper wire armature welding method of the present invention comprises the following steps:

[0006] Step 1: Install the product to be welded on the welding tool, use visual inspection equipment to detect foreign matter and oxidation spots on the outer surface of the copper wire of the product to be welded extending out of the welding tool, calculate the foreign matter and oxidation amount, and classify the foreign matter and oxidation spots according to the calculated surface foreign matter and oxidation amount.

[0007] Step 2, spraying flux on the copper wire according to the visual inspection result of step 1;

[0008] Step 3, preheating the copper wire welding point, the preheating temperature and preheating time are selected according to the visual inspection result of step 1;

[0009] Step 4: Use wave soldering equipment for soldering. The soldering temperature, soldering time, and nitrogen pressure are selected according to the visual inspection results of step 1.

[0010] Step 5: Use the welding quality inspection system to inspect the welding points.

[0011] Furthermore, in step 2, the soldering flux uses halogen-free soldering flux, water-based soldering flux, water-soluble soldering flux or lead-free soldering flux.

[0012] Furthermore, in step 2, the spraying method adopts ultrasonic spraying, screen sealing or pressure nozzle spraying.

[0013] Furthermore, in step 2, the spraying pressure is 0.03pa-0.3Mpa.

[0014] Furthermore, in step 2, when the oxidation ratio is less than or equal to 5%, the spraying time is ≤0.5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the spraying time is 0.2~1S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the spraying time is 0.8~2S.

[0015] Furthermore, in step 3, the preheating temperature ranges from 50 to 350° C., and the fluctuation range of the temperature during the preheating process is ±10 degrees.

[0016] Furthermore, in step 3, when the oxidation ratio is less than or equal to 5%, the preheating time is ≤5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the preheating time is 3 to 8S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the preheating time is 5 to 15S.

[0017] Further, in step 4, the welding temperature is greater than or equal to 270°C; when the oxidation ratio is less than or equal to 5%, the welding time is ≤1.5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the welding time is 1 to 2S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the welding time is 1.5 to 6S.

[0018] Furthermore, in step 4, the nitrogen pressure is 0.1-0.6 MPa.

[0019] Furthermore, in step 5, the inspection contents include whether there are cracks, cold solder joints, insufficient solder, sharp edges and pores in the solder joints.

[0020] Compared with the prior art, the effect of the present invention is positive and obvious. The hairpin flat copper wire armature welding method of the present invention has a simple production process, is easy to implement, is easy to operate, and has low equipment investment, and can achieve efficient and stable welding connection of the armature flat copper wire. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 The present invention is a schematic flow chart of a hairpin flat copper wire armature welding method.

[0022] Figure 2 Schematic diagram of hairpin flat copper wire armature.

[0023] Figure 3 Schematic diagram of the welding fixture for installing the hairpin flat copper wire armature.

[0024] Figure 4 A first schematic diagram of a hairpin flat copper wire extending out of a welding fixture.

[0025] Figure 5 A second schematic diagram of a hairpin flat copper wire extending out of a welding fixture.

[0026] Figure 6 Schematic diagram of the bad state of the welding point. DETAILED DESCRIPTION

[0027] The present invention is further described below in conjunction with an embodiment, but the present invention is not limited to the embodiment, and any similar variation of the present invention should be included in the protection scope of the present invention. The use of directions such as up, down, front, back, left, right, middle, inside, and outside in the present invention is only for the convenience of clear description, and is not a limitation of the technical solution of the present invention.

[0028] like Figure 1-Figure 6 As shown, a hairpin flat copper wire armature welding method of the present invention comprises the following steps:

[0029] Step 1: Install the product to be welded on the welding tool, use visual inspection equipment to detect foreign matter and oxidation spots on the outer surface of the copper wire of the product to be welded extending out of the welding tool, calculate the foreign matter and oxidation amount, and classify the foreign matter and oxidation spots according to the calculated surface foreign matter and oxidation amount.

[0030] Step 2, spraying flux on the copper wire according to the visual inspection result of step 1;

[0031] Step 3, preheating the copper wire welding point, the preheating temperature and preheating time are selected according to the visual inspection result of step 1;

[0032] Step 4: Use wave soldering equipment for soldering. The soldering temperature, soldering time, and nitrogen pressure are selected according to the visual inspection results of step 1.

[0033] Step 5: Use the welding quality inspection system to inspect the welding points.

[0034] Furthermore, in step 2, the soldering flux uses halogen-free soldering flux, water-based soldering flux, water-soluble soldering flux or lead-free soldering flux.

[0035] Furthermore, in step 2, the spraying method adopts ultrasonic spraying, screen sealing or pressure nozzle spraying.

[0036] Furthermore, in step 2, the spraying pressure is 0.03pa-0.3Mpa.

[0037] Furthermore, in step 2, when the oxidation ratio is less than or equal to 5%, the spraying time is ≤0.5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the spraying time is 0.2~1S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the spraying time is 0.8~2S.

[0038] Furthermore, in step 3, the preheating temperature ranges from 50 to 350° C., and the fluctuation range of the temperature during the preheating process is ±10 degrees.

[0039] Furthermore, in step 3, when the oxidation ratio is less than or equal to 5%, the preheating time is ≤5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the preheating time is 3 to 8S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the preheating time is 5 to 15S.

[0040] Further, in step 4, the welding temperature is greater than or equal to 270°C; when the oxidation ratio is less than or equal to 5%, the welding time is ≤1.5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the welding time is 1 to 2S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the welding time is 1.5 to 6S.

[0041] Furthermore, in step 4, the nitrogen pressure is 0.1-0.6 MPa.

[0042] Specifically, the welding tooling, visual inspection equipment, soldering flux, etc. in this embodiment all adopt well-known solutions in the prior art, which are well known to those skilled in the art and will not be described in detail here.

[0043] The working principle of this embodiment:

[0044] 1. Visual inspection

[0045] Products to be welded( Figure 2 ) Welding tooling needs to be installed. The design of welding tooling can be found in "An integral fixture for laser welding of hairpin flat wires in new energy vehicle motors", patent number ZL 202221621702.8.

[0046] After the welding product is installed with the integral fixture ( Figure 3 ), firstly, the outer surface of the copper wire extending out of the tooling ( Figure 4 and Figure 5) foreign matter and oxidation detection, the height of the copper wire sticking out of the tooling is set according to the actual project; the detection equipment uses visual detection, the machine equipment automatically detects the oxidation spots on the surface of the copper wire, calculates the foreign matter and oxidation amount, and divides the foreign matter and oxidation spots into percentage grades according to the calculated foreign matter and oxidation amount, which is convenient for the parameter setting and selection of the subsequent welding process. The specific percentage classification is shown in Table 1.

[0047]

[0048] Table 1

[0049] 2. Spraying flux:

[0050] The main functions of flux are to remove the oxide layer on the surface of the copper wire to be soldered, prevent secondary oxidation of the copper wire to be soldered during heating, and reduce the surface tension of the solder.

[0051] The flux can be sprayed and applied by halogen-free flux, water-based flux, water-soluble flux or lead-free flux.

[0052] The spraying method can be ultrasonic spraying, screen sealing method, and pressure nozzle spraying. The spraying requirement is atomized spraying. If the product to be welded is large, it can be sprayed in sections, and all the points that need to be welded are sprayed. The amount of flux used is selected according to the percentage of copper wire oxidation surface detected by visual inspection in the previous process. The spray pressure is set according to the actual selected flux. The general spraying pressure is 0.03Mpa-0.3Mpa. The relevant parameters are shown in Table 1.

[0053] 3. Preheating:

[0054] Preheating can be done by infrared preheating, which partially heats the copper wire welding points through infrared radiation and helps activate the flux, reducing the thermal shock to the copper wire caused by rapid temperature rise during wave soldering. It evaporates all absorbed moisture and the carrier solvent of the flux, removes the oxide on the surface of the copper wire to be soldered, and prepares for subsequent welding.

[0055] The preheating tube is placed near the location where the copper wire needs to be welded for preheating. The temperature of the preheating process needs to be precisely controlled, and the temperature fluctuation does not exceed ±10 degrees of the set temperature. The preheating range is verified according to the product to be welded and the flux. The preheating temperature setting is selected according to the percentage of the copper wire oxidation surface detected by visual inspection in the previous process.

[0056] The preheating temperature range is generally between 50 and 350 °C, but it needs to be set based on the process verification results of the actual copper wire size and welding length used. The preheating time is verified according to the size of the welding copper wire. The relevant parameters are shown in Table 1.

[0057] 4. Welding:

[0058] Wave soldering equipment should be selected for welding. Before welding, a camera is needed to locate and confirm the welding point. The welding process is the process of interaction between the surface of the welding copper wire, molten solder and the copper wire air. After welding, the two copper wires will be connected by the solder to form a whole. The soldering process must control the soldering temperature, welding time, nitrogen pressure, etc. The relevant parameters are shown in Table 1.

[0059] Soldering temperature: The temperature when soldering copper wire. The selection and setting of this temperature is related to the selected solder and needs to be verified and confirmed accordingly. The minimum temperature is not less than 270 degrees Celsius.

[0060] Welding time: the time from the start of welding the copper wire to the completion of welding the copper wire.

[0061] Nitrogen: Protect the welding point gas during welding to prevent oxidation during welding and cause poor welding.

[0062] 5. Welding inspection

[0063] After welding is completed, the welding points need to be inspected to confirm that the solder and copper wire are tightly connected, and the welding points are intact without cracks, cold solder joints, insufficient solder, pull tips and pores. Figure 6 shown.

[0064] Generally, welding inspection is performed by personnel or by welding quality inspection system. Due to the large number of welding points, it is not recommended to use personnel visual inspection, but to use equipment visual inspection, which automatically judges according to the program set inside the equipment visual inspection equipment.

[0065] The hairpin flat copper wire armature welding method of the present invention has a simple production process, is easy to implement, is convenient to operate, has low equipment investment, and can realize efficient and stable welding connection of the armature flat copper wire.

Claims

1. A hairpin flat copper wire armature welding method, characterized in that: The following steps are involved: Step 1: Install the product to be welded on the welding tool, use visual inspection equipment to detect foreign matter and oxidation spots on the outer surface of the copper wire of the product to be welded extending out of the welding tool, calculate the foreign matter and oxidation amount, and classify the foreign matter and oxidation spots according to the calculated surface foreign matter and oxidation amount. Step 2, spraying flux on the copper wire according to the visual inspection result of step 1; Step 3, preheating the copper wire welding point, the preheating temperature and preheating time are selected according to the visual inspection result of step 1; Step 4: Use wave soldering equipment for soldering. The soldering temperature, soldering time, and nitrogen pressure are selected according to the visual inspection results of step 1. Step 5: Use the welding quality inspection system to inspect the welding points.

2. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 2, the soldering flux uses a halogen-free soldering flux, a water-based soldering flux, a water-soluble soldering flux, or a lead-free soldering flux.

3. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 2, the spraying method adopts ultrasonic spraying, screen sealing method or pressure nozzle spraying.

4. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 2, the spraying pressure is 0.03pa-0.3Mpa.

5. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 2, when the oxidation ratio is less than or equal to 5%, the spraying time is ≤0.5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the spraying time is 0.2-1S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the spraying time is 0.8-2S.

6. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 3, the preheating temperature ranges from 50 to 350°C, and the temperature fluctuation range during the preheating process is ±10 degrees.

7. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 3, when the oxidation ratio is less than or equal to 5%, the preheating time is ≤5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the preheating time is 3 to 8S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the preheating time is 5 to 15S.

8. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 4, the welding temperature is greater than or equal to 270°C; when the oxidation ratio is less than or equal to 5%, the welding time is ≤1.5S; when the oxidation ratio is greater than 5% and less than or equal to 30%, the welding time is 1 to 2S; when the oxidation ratio is greater than 30% and less than or equal to 75%, the welding time is 1.5 to 6S.

9. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 4, the nitrogen pressure is 0.1-0.6 MPa.

10. A hairpin flat copper wire armature welding method according to claim 1, characterized in that: In step 5, the inspection contents include whether there are cracks, cold joints, insufficient solder, pull tips and pores in the solder joints.

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