Motor iron core welding method

Abstract

The invention discloses a motor iron core welding method, and belongs to the field of motors, a plurality of laminations are stacked in the vertical direction and staggered in the circumferential direction, so that welding grooves of every two adjacent laminations are connected and staggered, a plurality of welding beads are formed on the stacked iron core wall, and each welding bead is obliquely arranged; in the welding process, the laser welding device moves along a straight line, the iron core rotates in the circumferential direction, two welding paths are formed when each welding bead is welded through laser welding, each welding path extends to the tail end of the welding bead from the middle of the welding bead, and the two welding paths coincide in the middle of the welding bead. Welding beads of the iron core are uniformly distributed on the periphery, so that heat accumulation and stress concentration during welding are avoided; an industrial camera and a thermodetector are adopted to monitor the welding process, the industrial camera collects an infrared image during welding, the thermodetector collects a temperature signal during welding, and the state of a molten pool during welding is judged according to the infrared image and the temperature signal. And the output power of the laser welder and the circumferential rotation speed of the iron core are adjusted according to the molten pool temperature.

Description

Technical Field

[0001] This invention relates to electric motors, and more particularly to a method for welding the core of an electric motor. Background Technology

[0002] Iron cores are the most common component in motor manufacturing. They are stacked together and welded to form the motor core and are made from thin steel sheets (silicon steel sheets) that have been stamped. Different types and sizes of motor cores are made from iron cores of different sizes and shapes. The process of creating the motor core involves stacking and welding hundreds of iron cores together.

[0003] In existing iron core welding processes, the stacked iron cores remain stationary while the laser welder moves along the height of the iron core, forming a straight weld bead to weld and fix multiple iron cores together. Traditional straight welding paths lead to heat accumulation. Because the heat-affected zones overlap due to continuous welding along a straight line, this triggers an annealing effect on the silicon steel sheets. Furthermore, since the weld bead is distributed in a fixed location around the circumference of the iron core, residual stress from welding concentrates, affecting the quality of the iron core. Summary of the Invention

[0004] In order to overcome the shortcomings of the prior art, one of the objectives of the present invention is to provide a welding method for motor cores that can avoid heat accumulation and stress concentration during welding.

[0005] One of the objectives of this invention is achieved through the following technical solution:

[0006] A method for welding an electric motor core includes the following steps:

[0007] Stacking: Each stack of laminations has a welding groove on its edge. Multiple stacks of laminations are stacked vertically and staggered circumferentially, so that the welding grooves of adjacent stacks are connected and staggered, forming multiple weld beads on the iron core wall after stacking. Each weld bead is set at an angle.

[0008] Laser welding: Multiple stacked plates are pressed together by a pressure plate, and the laser welder welds the iron core. During the welding process, the laser welder moves in a straight line and the iron core rotates circumferentially. When the laser welder welds each weld bead, it is divided into two welding paths. Each welding path extends from the middle of the weld bead to the end of the weld bead, and the two welding paths partially overlap in the middle of the weld bead.

[0009] Online monitoring: The welding process is monitored using an industrial camera and a temperature measuring instrument. The industrial camera collects infrared images during welding, and the temperature measuring instrument collects temperature signals during welding. The state of the molten pool during welding is determined based on the infrared images and temperature signals.

[0010] Real-time adjustment: When the molten pool temperature is lower than the preset temperature range, increase the output power of the laser welder and / or reduce the rotation speed of the iron core circumferentially; when the molten pool temperature is higher than the preset temperature range, decrease the output power of the laser welder and / or increase the rotation speed of the iron core circumferentially; when the molten pool temperature is within the preset temperature range, maintain the current output power and the rotation speed of the iron core circumferentially.

[0011] Furthermore, in the stacking step, there are multiple weld beads, which are evenly distributed around the circumference of the iron core, and the line connecting the top and bottom of two adjacent weld beads is parallel to the axis of the iron core.

[0012] Furthermore, in the laser welding step, multiple laser welders simultaneously weld multiple weld passes, with adjacent laser welders having the same welding direction and the weld passes welded by adjacent laser welders being separated by one weld pass.

[0013] Furthermore, in the laser welding step, of the two welding paths, the first welding path is welded first, and the second welding path is welded later. The laser power of the first welding path is less than the laser power of the second welding path.

[0014] Furthermore, in the laser welding step, when multiple stacked sheets are pressed together by a pressure plate, the pressure plate is equipped with multiple pressure sensors, which are evenly distributed and measure the pressure of the pressure plate on the stacked sheets.

[0015] Furthermore, the two welding paths extend from the middle of the weld bead to the top of the weld bead and from the middle of the weld bead to the bottom of the weld bead, respectively.

[0016] Furthermore, in the online monitoring step, the area of ​​the molten pool is determined based on the infrared image, and the area of ​​the molten pool is used to determine whether two adjacent laminations have been successfully welded together.

[0017] Furthermore, in the stacking step, the weld bead is arranged along the outer or inner periphery of the stacked iron core.

[0018] Furthermore, the width of the welding groove is L, and the width of the misalignment between adjacent stacked pieces is 20%L-40%L.

[0019] Furthermore, in the laser welding step, when each welding path reaches the end, a current decay process is added when the arc is extinguished, and the welding current gradually decreases after welding until the arc is extinguished.

[0020] Compared with existing technologies, the motor core welding method of the present invention uses multiple laminations stacked vertically and staggered circumferentially to connect and offset the welding grooves of adjacent laminations, forming multiple weld beads on the stacked core wall, each weld bead being inclined; during the welding process, the laser welder moves in a straight line and the core rotates circumferentially, and the laser welding of each weld bead is divided into two welding paths, each welding path extending from the middle of the weld bead to the end of the weld bead, with the two welding paths partially overlapping in the middle of the weld bead, so that the weld beads of the core are evenly distributed around the perimeter to avoid heat accumulation and stress concentration during welding. Attached Figure Description

[0021] Figure 1 This is a flowchart of the motor core welding method of the present invention;

[0022] Figure 2 This is a schematic diagram of the welding path of the same weld bead in the motor core welding method of the present invention;

[0023] Figure 3 This is a schematic diagram illustrating the welding sequence when multiple laser welders are used for simultaneous welding of the motor core welding method of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] It should be noted that when a component is said to be "fixed to" another component, it can be directly on the other component or it can be fixed through another intermediate component. When a component is said to be "connected to" another component, it can be directly connected to the other component or it may be fixed through another intermediate component. When a component is said to be "set on" another component, it can be set directly on the other component or it may be set through another intermediate component. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0026] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0027] like Figures 1 to 3As shown, the motor core welding method of the present invention includes the following steps:

[0028] Stacking: Each stack of laminations has a welding groove on its edge. Multiple stacks of laminations are stacked vertically and staggered circumferentially, so that the welding grooves of adjacent stacks are connected and staggered, forming multiple weld beads on the iron core wall after stacking. Each weld bead is set at an angle.

[0029] Laser welding: Multiple stacked plates are pressed together by a pressure plate, and the laser welder welds the iron core. During the welding process, the laser welder moves in a straight line and the iron core rotates circumferentially. When the laser welder welds each weld bead, it is divided into two welding paths. Each welding path extends from the middle of the weld bead to the end of the weld bead, and the two welding paths partially overlap in the middle of the weld bead.

[0030] Online monitoring: The welding process is monitored using an industrial camera and a temperature measuring instrument. The industrial camera collects infrared images during welding, and the temperature measuring instrument collects temperature signals during welding. The state of the molten pool during welding is determined based on the infrared images and temperature signals.

[0031] Real-time adjustment: When the molten pool temperature is lower than the preset temperature range, increase the output power of the laser welder and / or reduce the rotation speed of the iron core circumferentially; when the molten pool temperature is higher than the preset temperature range, decrease the output power of the laser welder and / or increase the rotation speed of the iron core circumferentially; when the molten pool temperature is within the preset temperature range, maintain the current output power and the rotation speed of the iron core circumferentially.

[0032] During the stacking process, each stack of laminations has multiple welding grooves on its edge, evenly distributed around the circumference of the laminations to form multiple weld beads. These weld beads are evenly distributed around the core circumference, with the lines connecting the top and bottom of adjacent weld beads parallel to the core axis, creating a continuous structure on the core circumference and preventing stress concentration. Specifically, the width of the welding groove is L, and the misalignment width between adjacent laminations is 20%L-40%L, ensuring the weld beads extend circumferentially while avoiding excessive misalignment that could reduce welding strength. Because the weld beads are angled, they move along the core circumference during welding, preventing heat buildup. The weld beads are positioned along the outer or inner circumference of the stacked core; in this embodiment, for ease of operation of the welding equipment, the weld beads are positioned on the outer circumference of the stacked core.

[0033] In the laser welding process, when multiple stacked pieces are pressed together using a pressure plate, the pressure plate is equipped with multiple pressure sensors. These sensors are evenly distributed and measure the pressure exerted by the pressure plate on the stacked pieces. Since a normal weld joint takes approximately 20ms from the welding start signal to successful arc ignition, and with both the tungsten electrode and the workpiece cold, it may take 100ms or longer to successfully ignite the arc. If the laser welder starts calculating the welding time immediately after giving the welding start signal and immediately gives the welding end signal after the welding time ends, the actual welding time will be shortened due to the excessively long arc ignition time, ultimately leading to missed welds during cooling. Therefore, in the welding path of this application, the welding start point is in the middle of the weld bead, and the welding end point is at the end of the weld bead. Furthermore, the starting points of the two welding paths for the same weld bead partially overlap to avoid missed welds at the starting point. Specifically, the two welding paths extend from the middle of the weld bead to the top and from the middle of the weld bead to the bottom, respectively.

[0034] During welding, the electric arc is affected by gas and current fluctuations, forming fine weld beads resembling water ripples at the weld joint. If the arc is extinguished immediately after welding and the weld immediately enters a cooling state, these water ripples will remain at the weld joint, affecting its gloss and reducing its pull-out strength. Therefore, at the end of each welding path, a current decay process is incorporated when the arc is extinguished. The welding current gradually decreases until the arc is extinguished. The small current during this decay process melts the water ripples generated during welding into smooth spheres. This method effectively suppresses the formation of water ripples on the weld joint, promotes a metallic luster, and improves pull-out strength.

[0035] In two welding paths for the same weld bead, the path welded first is called the first welding path, and the path welded later is called the second welding path. The laser power used in the first welding path is less than that used in the second welding path. To improve welding efficiency, multiple laser welders simultaneously weld multiple weld beads. However, to prevent interference between the arc magnetic field and resulting in poor weld joints, adjacent laser welders need to maintain a distance. Therefore, during welding, adjacent laser welders have the same welding direction, and the weld beads welded by adjacent laser welders are separated by one weld bead. See details... Figure 3In one embodiment, step 1: Multiple laser welders first weld downwards along a first welding path, with an unwelded weld bead between adjacent weld beads. Step 2: Multiple laser welders weld upwards along the first welding path within the unwelded weld beads, with a half-welded weld bead between adjacent weld beads. Step 3: Multiple laser welders return to the weld bead from step 1 and weld upwards along a second welding path within the half-welded weld bead, with a half-welded weld bead between adjacent weld beads. Step 4: Multiple laser welders return to the weld bead from step 2 and weld downwards along the second welding path within the half-welded weld bead, with a completed weld bead between adjacent weld beads. Through these steps, not only are adjacent laser welders kept at a distance, but the same weld bead is also welded intermittently, avoiding heat accumulation.

[0036] In the online monitoring process, the area of ​​the molten pool is determined based on the infrared image, and the area of ​​the molten pool is used to determine whether the welding connection between two adjacent laminations has been completed.

[0037] Compared to existing technologies, the motor core welding method of this invention uses multiple laminations stacked vertically and staggered circumferentially to connect and offset the welding grooves of adjacent laminations, forming multiple weld beads on the stacked core wall. Each weld bead is inclined. During welding, the laser welder moves in a straight line while the core rotates circumferentially. Each weld bead is welded via two welding paths, each extending from the middle to the end of the weld bead. The two welding paths partially overlap in the middle of the weld bead, ensuring a uniform distribution of weld beads around the core and preventing heat accumulation and stress concentration during welding. Furthermore, by maintaining distance between adjacent laser welders and welding the same weld bead alternately, heat accumulation is avoided.

[0038] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention. These are all equivalent modifications and improvements made to the above embodiments based on the essential technology of the present invention, and all of these fall within the protection scope of the present invention.

Claims

1. A method for welding an electric motor core, characterized in that, Includes the following steps: Stacking: Each stack of laminations has a welding groove on its edge. Multiple stacks of laminations are stacked vertically and staggered circumferentially, so that the welding grooves of adjacent stacks are connected and staggered, forming multiple weld beads on the iron core wall after stacking. Each weld bead is set at an angle. Laser welding: Multiple stacked plates are pressed together by a pressure plate, and the laser welder welds the iron core. During the welding process, the laser welder moves in a straight line and the iron core rotates circumferentially. When the laser welder welds each weld bead, it is divided into two welding paths. Each welding path extends from the middle of the weld bead to the end of the weld bead, and the two welding paths partially overlap in the middle of the weld bead. Online monitoring: The welding process is monitored using an industrial camera and a temperature measuring instrument. The industrial camera collects infrared images during welding, and the temperature measuring instrument collects temperature signals during welding. The state of the molten pool during welding is determined based on the infrared images and temperature signals. Real-time adjustment: When the molten pool temperature is lower than the preset temperature range, increase the output power of the laser welder and / or reduce the rotation speed of the iron core circumferentially; when the molten pool temperature is higher than the preset temperature range, decrease the output power of the laser welder and / or increase the rotation speed of the iron core circumferentially; when the molten pool temperature is within the preset temperature range, maintain the current output power and the rotation speed of the iron core circumferentially.

2. The method for welding motor cores according to claim 1, characterized in that: In the stacking step, there are multiple weld beads, which are evenly distributed around the circumference of the iron core. The line connecting the top and bottom of two adjacent weld beads is parallel to the axis of the iron core.

3. The method for welding motor cores according to claim 2, characterized in that: In the laser welding step, multiple laser welders simultaneously weld multiple weld passes, with adjacent laser welders having the same welding direction and the weld passes welded by adjacent laser welders being separated by one weld pass.

4. The method for welding motor cores according to claim 1, characterized in that: In the laser welding step, of the two welding paths, the first welding path is welded first, and the second welding path is welded later. The laser power of the first welding path is less than the laser power of the second welding path.

5. The method for welding motor cores according to claim 1, characterized in that: In the laser welding step, when multiple stacked sheets are pressed together by a pressure plate, the pressure plate is equipped with multiple pressure sensors. These multiple pressure sensors are evenly distributed and measure the pressure of the pressure plate on the stacked sheets.

6. The method for welding motor cores according to claim 1, characterized in that: The two welding paths extend from the middle of the weld bead to the top of the weld bead and from the middle of the weld bead to the bottom of the weld bead, respectively.

7. The method for welding motor cores according to claim 1, characterized in that: In the online monitoring step, the area of ​​the molten pool is determined based on the infrared image, and the area of ​​the molten pool is used to determine whether two adjacent laminations have been successfully welded together.

8. The method for welding motor cores according to claim 1, characterized in that: In the stacking step, the weld bead is arranged along the outer or inner periphery of the stacked iron core.

9. The method for welding motor cores according to claim 1, characterized in that: The width of the welding groove is L, and the width of the misalignment between adjacent stacked pieces is 20%L-40%L.

10. The method for welding motor cores according to claim 1, characterized in that: In the laser welding step, when each welding path reaches the end, a current decay process is added when the arc is extinguished, and the welding current gradually decreases after welding until the arc is extinguished.

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