Method for preventing crack propagation of nickel-plated layer on rotor yoke assembly through laser surface modification

Abstract

The invention discloses a method for preventing crack propagation of a nickel-plated layer on a rotor yoke assembly through laser surface modification, and belongs to the technical field of surface treatment of rotor yoke assemblies of small and medium-sized motors. According to the method, laser surface cladding is carried out near the weld joint fusion line, cracking or crack propagation of a nickel layer on the fusion line is avoided, the cladding area can be accurately controlled, and the machining cost is controlled. By adopting a laser welding method, the width and depth of a fusion area can be accurately controlled, and a laser surface cladding area can be accurately controlled. Workpiece deformation caused in the laser surface cladding process can be effectively avoided.

Description

Technical Field

[0001] The invention discloses a method for preventing crack propagation of a nickel-plated layer in a rotor yoke assembly by laser surface modification, and belongs to the technical field of surface treatment of rotor yoke assemblies of small and medium-sized motors. Background Art

[0002] The alternator rotor yoke assembly is usually made by embedding magnetic isolation blocks (austenitic stainless steel) in the magnetic conductive area (alloy steel) and welding them using electron beam welding; or by milling grooves at the magnetic isolation position on the magnetic isolation area (alloy steel) bar stock, and filling the austenitic solder into the grooves by argon arc welding and other methods to form a magnetic isolation metal with austenite as the main structure. The former has a higher processing cost, while the latter has higher processing efficiency and lower equipment investment.

[0003] When using the argon arc welding filling method, in order to ensure the magnetic field of the motor, the mutual melting zone between the alloy steel and the filling solder on the fusion line of the rotor yoke assembly is required to be small to ensure the stability of the magnetic conductor and the magnetic shield. After the rotor yoke assembly is processed and formed, it needs to be nickel-plated as a whole to prevent rust. Due to the large difference in the thermal expansion coefficients of the austenitic magnetic shield and the alloy steel magnetic conductor, the two metals on the weld fusion line rarely dissolve each other, forming two clearly defined areas on the fusion line. In the later stage, under the condition of large temperature changes, the nickel layer is prone to cracking at stress concentration locations such as the flange at the weld fusion line of the rotor yoke assembly. It affects the appearance quality of the rotor yoke assembly and also reduces the protective effect of nickel plating on the magnetic conductor. Summary of the invention

[0004] The purpose of the present invention is to form a laser weld area of ​​a certain width and depth on the fusion line of the rotor yoke assembly by a laser surface modification method, disperse the stress of the nickel layer on the fusion line caused by temperature changes, and reduce the risk of cracking and crack propagation of the nickel layer at this position.

[0005] The technical solution of the present invention is: a method for preventing crack propagation of a nickel-plated layer in a rotor yoke assembly by laser surface modification, comprising the following steps:

[0006] 1) Use alcohol to clean the area of ​​the rotor yoke assembly that needs to be clad. Make sure there is no oil on the surface. Let it dry before cladding.

[0007] 2) Laser cladding is performed on the circular surface of one side of the rotor yoke assembly and the side circumference near the flange position by laser welding;

[0008] 3) When performing surface cladding on a circular surface, the laser pulse energy is adjusted within the range of 6J-8J, the ratio of the pulse width value to the single pulse energy is between 1.5-2.5; the welding speed is 5mm / s-10mm / s;

[0009] 4) When performing surface cladding near the flange position on the side circumference, the laser pulse energy is adjusted within the range of 8J-10J; the ratio of the pulse width value to the single pulse energy should be greater than 2-3; the welding speed is 6mm / s-10mm / s.

[0010] Furthermore, during laser cladding, argon gas is used for protection.

[0011] Furthermore, the laser cladding depth is between 0.3 mm and 0.5 mm.

[0012] Furthermore, cotton yarn alcohol was used for cleaning after laser cladding.

[0013] Furthermore, the circumferential position of the rotor assembly is perpendicular to the laser beam.

[0014] Furthermore, the cladding area is checked to see if there are defects such as spatter and voids, and the voids and other defects are repaired by welding, and the filler wire is the same as the wire brand used in the stacking welding. Furthermore, the laser welding is to form a molten pool on the surface of the workpiece during the welding process, and form a surface modification area on the fusion line through metal mutual dissolution.

[0015] Furthermore, the laser welding adopts four-axis linkage laser welding equipment.

[0016] The beneficial effects of the present invention are:

[0017] A laser welding method is proposed to perform laser surface cladding near the weld fusion line to avoid cracking or crack extension of the nickel layer on the fusion line, accurately control the cladding area, and control the processing cost. The laser welding method can accurately control the width and depth of the fusion area and the laser surface cladding area. By adopting an energy-concentrated laser welding method, deformation of the workpiece caused during the laser surface cladding process can be effectively avoided. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 3D image of the rotor yoke assembly blank;

[0019] Figure 2 Left view and front view of the assembly after welding;

[0020] Figure 3 Front view of the rotor yoke assembly;

[0021] Figure 4 Schematic diagram of the stress concentration position of the rotor yoke assembly flange;

[0022] Figure 5 Schematic diagram of the cladding position on the surface of the rotor yoke assembly;

[0023] Figure 6Schematic diagram of laser surface modification of the weld line of the rotor yoke assembly. DETAILED DESCRIPTION

[0024] The present invention is further described below in conjunction with the accompanying drawings:

[0025] exist Figure 1 The groove of the rotor yoke assembly blank is filled with austenitic stainless steel welding wire. The final structure of the rotor yoke assembly is obtained by machining. Figure 2 shown.

[0026] like Figure 3 As shown in the figure, it is a circumferential cross-sectional view of the rotor yoke assembly. Figure 4 As shown, this is the stress concentration area of ​​the nickel layer of the nickel-plated rotor yoke assembly, and the nickel layer has a strong tendency to crack.

[0027] like Figure 5 The laser surface modification area is shown in the figure. The laser welding equipment with a four-axis linkage workbench is used to weld the area marked in the figure to form a metal transition area to reduce the stress concentration problem on the fusion line. Figure 6 shown.

[0028] The method of laser surface modification to prevent the expansion of nickel-plated cracks in the rotor yoke assembly includes checking the circuit and gas path of the equipment before use and adjusting the laser welding machine position. The rotor assembly to be laser clad is placed on the rotating workbench of the laser welding machine, and the position of the ring on the rotor yoke assembly is corrected by CCD. Specifically, the following steps are included:

[0029] 1) Use alcohol to clean the area of ​​the rotor yoke assembly that needs to be clad. Make sure there is no oil on the surface. Let it dry before cladding.

[0030] 2) Laser cladding is performed on the circular surface of one side of the rotor yoke assembly and the side circumference near the flange position by laser welding;

[0031] 3) When performing surface cladding on a round surface, the structure at this location is thin and easily deformed, which is not conducive to heat dissipation. The laser pulse energy is adjusted within the range of 6J-8J, and the ratio of the pulse width value to the single pulse energy is between 1.5-2.5; the welding speed is 5mm / s-10mm / s;

[0032] 4) When performing surface cladding near the flange position on the side circumference, since the wall thickness at this position exceeds 6 mm and the heat dissipation is faster, the laser pulse energy is adjusted within the range of 8J-10J; the ratio of the pulse width value to the single pulse energy should be greater than 2-3; the welding speed is 6mm / s-10mm / s.

[0033] During laser cladding, argon gas is used for protection, the laser cladding depth is between 0.3mm-0.5mm, and cotton yarn alcohol is used for cleaning after laser cladding.

[0034] The circumferential position of the rotor assembly is perpendicular to the laser beam.

[0035] Check the cladding area to see if there are any defects such as spatter and voids. Perform repair welding on the voids and other defects. The filler wire should be the same grade as the wire used for stacking welding. Fold the high points of the repair welding as needed. Measure the minimum width of the cladding area and make additional welds if it does not meet the requirements. Measure the height of the side cladding and remove the high points by fracturing and machining.

[0036] The laser welding is to form a molten pool on the surface of the workpiece during the welding process, and form a surface modification area on the fusion line through metal mutual dissolution.

[0037] The laser welding adopts a four-axis linkage laser welding machine, which can efficiently obtain the laser surface modification area.

Claims

1. A method for preventing crack propagation of nickel-plated layer in rotor yoke assembly by laser surface modification, characterized in that: The following steps are involved: 1) Use alcohol to clean the area of ​​the rotor yoke assembly that needs to be clad. Make sure there is no oil on the surface. Let it dry before cladding. 2) Laser welding is used to clad the circular surface of one side of the rotor yoke assembly and the side circumference near the flange position; 3) When performing surface cladding on a circular surface, the laser pulse energy is adjusted within the range of 6J-8J, the ratio of the pulse width value to the single pulse energy is between 1.5-2.5; the welding speed is 5mm / s-10mm / s; 4) When performing surface cladding near the flange position on the side circumference, the laser pulse energy is adjusted within the range of 8J-10J; the ratio of the pulse width value to the single pulse energy should be greater than 2-3; the welding speed is 6mm / s-10mm / s.

2. The method for preventing crack propagation of the nickel-plated layer in a rotor yoke assembly by laser surface modification according to claim 1, characterized in that: During laser cladding, argon gas is used for protection.

3. The method for preventing crack propagation of the nickel plating layer in a rotor yoke assembly by laser surface modification according to claim 1, characterized in that: The laser cladding depth is between 0.3mm-0.5mm.

4. The method for preventing crack propagation of the nickel plating layer in a rotor yoke assembly by laser surface modification according to claim 1, characterized in that: After cladding, use cotton gauze and alcohol for cleaning.

5. The method for preventing crack propagation of the nickel-plated layer in a rotor yoke assembly by laser surface modification according to claim 1, characterized in that: The circumferential position of the rotor assembly is perpendicular to the laser beam.

6. The method for preventing crack propagation of the nickel plating layer in a rotor yoke assembly by laser surface modification according to claim 1, characterized in that: Check the cladding area to see if there are defects such as spatter and voids, and perform repair welding on the voids and other defects. The filler wire should be the same brand as the wire used in the stacking welding.

7. The method for preventing crack propagation of nickel plating layer in rotor yoke assembly by laser surface modification according to claim 1, characterized in that: The laser welding is to form a molten pool on the surface of the workpiece during the welding process, and form a surface modification area on the fusion line through metal mutual dissolution.

8. The method of laser surface modification to prevent crack propagation of nickel plating layer in rotor yoke assembly according to claim 1, characterized in that: The laser welding adopts a four-axis linkage laser welding machine equipment.

Images