Motor rotor for new energy automobile and friction stir welding manufacturing method thereof

Abstract

The invention discloses a motor rotor for a new energy automobile and a friction stir welding manufacturing method of the motor rotor. The motor rotor comprises a rotor main core, a plurality of assembly strips and two end rings. A plurality of reserved slot holes are formed in the outer side wall of the rotor main core, the assembling strips are embedded in the slot holes in a matched mode, the inner ring shape of the end ring is the same as the outer circumferential contour shape of an end circular face formed after the rotor main core is assembled with the assembling strips, and the outer end face of the end ring is flush with the end circular face; and the whole body formed by the rotor main core and the assembly strips is connected with the end rings through friction stir welding. According to the invention, the structural design of the motor copper rotor is combined with the friction stir welding process method, so that the problem of large deformation of the end ring is solved; and after a circle of welding is completed, a tail hole is avoided by adopting pumpback type friction stir welding, so that the quality of the motor rotor is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor rotors, and in particular to a motor rotor for new energy vehicles and a friction stir welding method for manufacturing the same. Background Art

[0002] The drive motor, battery assembly and electronic control assembly are collectively known as the three electrics, which are the core components of new energy vehicles. The drive motor is the key component that converts the battery's electrical energy into the vehicle's mechanical energy. The drive motor of new energy vehicles requires a wide speed adjustment range, especially to adapt to the requirements of high speed, high power density, safety and reliability, lightweight and strong overload capacity, which are much more stringent than general industrial drive motors.

[0003] The copper rotor is an important component of the new motor of new energy vehicles. Its structure is mostly in the form of copper bars and rotor main cores. The existing mainstream technology is to weld the copper bars and the rotor main core by brazing or laser welding, or to cast the copper bars and the rotor main core into one body by casting. The above processing and manufacturing methods all have certain defects.

[0004] At present, there are reports of using friction stir welding to weld the rotor main core and copper bars. Friction stir welding generates heat through the friction between the high-speed rotating stirring head and the workpiece to soften the material. When the stirring head moves along the welding interface, the softened material is filled into the cavity formed on the rear side of the stirring head under the rotation and extrusion of the stirring head to form a complete weld. Friction stir welding has the advantages of high strength and stable quality, but there are some problems in the conventional friction stir welding of motor rotors: for example, the friction stir welding device and method of the motor rotor with patent publication number CN105171227A has a tail hole at the end; at the same time, when the welding depth of friction stir welding is large, the end ring will be greatly deformed, affecting the subsequent assembly. Summary of the invention

[0005] The purpose of the present invention is to solve the above problems and provide a motor rotor for new energy vehicles and a stir friction welding manufacturing method thereof, so as to improve the processing quality of the motor rotor.

[0006] The present invention is achieved through the following technical solutions:

[0007] A first aspect of the present application provides a motor rotor for a new energy vehicle, comprising a rotor main core, a plurality of assembly strips and two end rings;

[0008] The outer side wall of the rotor main core is provided with a plurality of reserved slot holes, and the assembly strip is fitted into the slot holes. The length of the assembly strip is the same as the length of the rotor main core. After the assembly strip is inserted into the slot hole, its head end and tail end are exposed and the head and tail end surfaces of the assembly strip are respectively flush with the upper and lower end surfaces of the rotor main core to form end circular surfaces;

[0009] The end ring is a circular ring structure, the inner ring shape of the end ring is the same as the outer circumferential contour shape of the end circular surface formed after the rotor main core is assembled with the assembly strip, and the outer end surface of the end ring is flush with the end circular surface;

[0010] The rotor main core, the assembly strip and the end ring are connected to each other through friction stir welding.

[0011] To optimize the above technical solutions, the specific measures taken also include:

[0012] The slot holes are symmetrically arranged with the axis of the rotor main core as the center line, and the shapes of the assembly strips and the slot holes are matched.

[0013] The main core of the rotor is a rotor iron core, and the assembly strip is a copper strip.

[0014] The second aspect of the present application provides a friction stir welding manufacturing method for a motor rotor for a new energy vehicle, comprising the following steps:

[0015] Step S1: Assemble the assembly strip and the rotor main core, insert the assembly strip into each slot hole respectively, and make the end surface of the assembly strip and the rotor main core flush;

[0016] Step S2: disposing a first end ring outside one end of a whole formed by the rotor main core and the assembly strip, so that the outer end surface of the first end ring is flush with the end formed by the assembly strip and the rotor main core;

[0017] Step S3: connecting the rotor main core and the assembly strip at this end to the first end ring by friction stir welding;

[0018] Step S4: turning over the rotor main core, and setting the second end ring outside the other end of the whole formed by the rotor main core and the assembly strip, so that the outer end surface of the second end ring is flush with the other end formed by the assembly strip and the rotor main core;

[0019] Step S5: connecting the rotor main core and the assembly strip at the other end to the second end ring by friction stir welding.

[0020] The rotor main core is clamped and positioned by a fixed heating fixture, and the clamping and fixing part of the fixed heating fixture is the outer side of the end of the rotor main core, the assembly strip and the end ring assembly. A preheating treatment is performed before the stir friction welding in step S3 and step S5.

[0021] Furthermore, the friction stir welding is a retraction type friction stir welding, specifically:

[0022] After one round of welding along the connecting surface between the integral body formed by the rotor main core and the assembly strip and the end ring, the retraction operation begins; during the retraction operation, the stirring needle rotates synchronously with the shaft shoulder while the stirring needle moves upward relative to the shaft shoulder until the lower end surface of the stirring needle is flush with the lower end surface of the shaft shoulder, completing the retraction operation to eliminate the tail hole at the weld end surface.

[0023] Furthermore, the welding feed speed of the friction stir welding is 100-3000 mm / min, the rotation speed of the stirring needle is 400-8000 rpm, and the inclination angle of the main shaft is 2-4°.

[0024] Preferably, during the retraction operation of the friction stir welding, the speed at which the stirring needle moves upward relative to the shaft shoulder is 10-20 mm / min.

[0025] Furthermore, the heating temperature of the fixed heating fixture is 300-400°C, the heating rate is 10-40°C / s, and after heating to the predetermined heating temperature, it is maintained for 15-30s.

[0026] Furthermore, the upsetting force during the friction stir welding is 5000N-11000N, and the welding depth is 4-10mm; the friction stir welding adopts a constant pressure control method.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] The present invention provides a motor rotor for new energy vehicles and a stir friction welding manufacturing method thereof. The problem of large deformation of the end ring is solved by combining the structural design of the motor copper rotor with the stir friction welding process method. After completing one round of welding, the tail hole is avoided by using retraction-type stir friction welding to improve the quality of the motor rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 : A schematic structural diagram of a motor rotor for a new energy vehicle of the present invention.

[0030] Figure 2 : Schematic diagram of the structure of the retraction type friction stir welding tool.

[0031] In the figure: 1-rotor main core, 2-assembly bar, 3-end ring, 4-friction stir welding tool, 401-stirring needle, 402-shaft shoulder, 5-fixed heating fixture. DETAILED DESCRIPTION

[0032] The above contents of the present invention are further described in detail below in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following embodiments, and all technologies realized based on the above contents of the present invention belong to the scope of the present invention.

[0033] The present invention provides a motor rotor for new energy vehicles, comprising a rotor main core 1, a plurality of assembly strips 2 and two end rings 3;

[0034] The outer wall of the rotor main core 1 is provided with a plurality of reserved slot holes, and the assembly strip 2 is fitted into the slot holes. The length of the assembly strip 2 is the same as that of the rotor main core 1. After the assembly strip 2 is inserted into the slot hole, its head end and tail end are exposed, and the head and tail end surfaces of the assembly strip 2 are respectively flush with the upper and lower end surfaces of the rotor main core 1, forming end circular surfaces;

[0035] The end ring 3 is a circular ring structure, the inner ring shape of the end ring 3 is the same as the outer circumferential contour shape of the end circular surface formed after the rotor main core 1 is assembled with the assembly strip 2, and the outer end surface of the end ring 3 is flush with the end circular surface;

[0036] The rotor main core 1 and the assembly strip 2 are integrally connected to the end ring 3 by friction stir welding.

[0037] The slot holes are symmetrically arranged with the axis of the rotor main core 1 as the center line, and the shapes of the assembly strips 2 match those of the slot holes.

[0038] Preferably, the rotor main core 1 is a rotor iron core, and the assembly bar 2 is a copper bar.

[0039] The present invention also provides a friction stir welding manufacturing method for a motor rotor for a new energy vehicle, comprising the following steps:

[0040] Step S1: Assemble the assembly strip 2 and the rotor main core 1, insert the assembly strip 2 into each slot hole respectively, and make the end surface of the assembly strip 2 and the rotor main core 1 flush;

[0041] Step S2: disposing the first end ring 3 outside one end of the whole formed by the rotor main core 1 and the assembly strip 2, so that the outer end surface of the first end ring 3 is flush with the end formed by the assembly strip 2 and the rotor main core 1;

[0042] Step S3: connecting the rotor main core 1 and the assembly strip 2 at this end to the first end ring 3 by friction stir welding;

[0043] Step S4: Turn over the rotor main core 1, and arrange the second end ring 3 outside the other end of the whole formed by the rotor main core 1 and the assembly strip 2, so that the outer end surface of the second end ring 3 is flush with the other end formed by the assembly strip 2 and the rotor main core 1;

[0044] Step S5: connecting the rotor main core 1 and the assembly strip 2 at the other end to the second end ring 3 by friction stir welding.

[0045] The rotor main core 1 is clamped and positioned by a fixed heating fixture 5. The clamping and fixing part of the fixed heating fixture 5 is the outer side of the end where the rotor main core 1, the assembly strip 2 and the end ring 3 are assembled. A preheating treatment is performed before the stir friction welding in step S3 and step S5.

[0046] Friction stir welding is a retraction type friction stir welding, specifically:

[0047] After one round of welding along the connecting surface between the integral body formed by the rotor main core 1 and the assembly strip 2 and the end ring 3, the retraction operation begins; during the retraction operation, the stirring needle 401 rotates synchronously with the shaft shoulder 402, and the stirring needle 401 moves upward relative to the shaft shoulder 402 until the lower end surface of the stirring needle 401 is flush with the lower end surface of the shaft shoulder 402, completing the retraction operation to eliminate the tail hole at the welding end surface.

[0048] In some embodiments, the welding feed speed of the friction stir welding is 100-3000 mm / min, the rotation speed of the stirring needle 401 is 400-8000 rpm, and the inclination angle of the main shaft is 2-4°.

[0049] Preferably, the welding feed speed of the friction stir welding is 200-800 mm / min, the rotation speed of the stirring needle 401 is 500-1500 rpm, and the inclination angle of the main shaft is 2-3°.

[0050] When the friction stir welding is performed with a retraction operation, the speed at which the stirring needle 401 moves upward relative to the shaft shoulder 402 is 10-20 mm / min, and the positioning accuracy of the retraction operation is ±0.1 mm.

[0051] In some embodiments, the heating temperature of the fixed heating fixture 5 is 300-400° C., the heating rate is 10-40° C. / s, and the temperature is maintained for 15-30 seconds after being heated to the predetermined heating temperature.

[0052] In some embodiments, the upsetting force during the friction stir welding is 5000N-11000N, the welding depth is 4-10mm, and the friction stir welding adopts a constant pressure control method.

[0053] Finally, the stirring tool is replaced with a milling cutter, and the two end rings 3 after welding are milled according to the requirements of the drawing to remove the excess parts to achieve the final forming of the parts.

[0054] In some embodiments, the rotation speed of the milling process is 8000-12000 rpm; the feed speed of the milling process is 200-2000 mm / min.

[0055] The present invention is further described in detail below in conjunction with specific embodiments:

[0056] Example 1

[0057] The structure of the motor rotor for new energy vehicles includes a rotor core, several copper bars and two copper rings; the copper bars are inserted into slot holes reserved on the outside of the rotor core, and after insertion, the head and tail ends of the copper bars are exposed from the rotor core; the copper ring is a circular ring structure; ensure that the overall end surface formed by the copper bar inserted into the slot hole of the rotor core is flush with the outer end surface of the copper ring; after the copper ring and the copper bar are assembled on the rotor core, they are welded into a whole by using the retraction type stir friction welding method.

[0058] Among them, the outer diameter of the rotor core is 240mm, the inner diameter is 80mm, and the length is 320mm; there are 11 copper bars, and the material of the copper bars and the copper rotor is T1 or T2 pure copper; a retractable stir friction welding tool 4 with a needle length of 7.7mm and a shoulder 402 diameter of 18mm is used.

[0059] The copper rotor processing process of this embodiment includes the following steps:

[0060] (1) Assemble the copper bars and the rotor core. During the assembly process, fix the rotor core with a fixed heating fixture 5, and then insert the copper bars into the corresponding slot holes of the rotor core one by one, ensuring that both ends of the head and tail of each copper bar are exposed to the rotor core, and the end faces of the head and tail are flush with the upper and lower end faces of the rotor core;

[0061] (2) Assemble the copper ring, copper bar and rotor core. During the assembly process, fix the rotor core and the copper bar installed on the rotor core with a fixed heating fixture 5, adjust the position of the copper ring so that its end face is flush with the end face of the copper bar and the end face of the rotor core, and ensure that its inner ring is tightly fitted with the copper bar and the rotor core;

[0062] (3) Start the heating function of the fixed heating fixture 5, and use electromagnetic induction heating to preheat the copper ring, copper bar and rotor core waiting for welding area of ​​the end surface. The heating temperature of the fixed heating fixture 5 is 320°C, and the heating rate is 20°C / s. After heating to the set temperature, keep it for 20s and stop heating;

[0063] (4) The preheated copper bars, the outer periphery of the rotor core and the inner ring of the copper ring are welded by friction stir welding. The rotation speed during welding is 560 rpm, the feed speed is 280 mm / min, and the inclination angle of the main shaft is 2.5°. After welding for one circle, i.e. 360°, the retraction operation is started: the stirring needle 401 rotates synchronously with the shaft shoulder 402 and moves upward relative to the shaft shoulder 402. At this time, the stirring needle 401 and the shaft shoulder 402 rotate synchronously at a speed of 560 rpm, and continue to move along the circumference at 280 mm / min. At the same time, the stirring needle 401 is driven by an external motor and moves upward relative to the shaft shoulder 402 at a speed of 15 mm / min until the lower end surface of the stirring needle 401 is flush with the lower end surface of the shaft shoulder 402, completing the retraction operation, thereby eliminating the tail hole at the welding end surface;

[0064] (5) Using the fixed heating fixture 5, flip the part 180° and keep it fixed, set another copper ring on the outside of the other end of the whole formed by the rotor core and the copper bar, adjust the position of the copper ring so that its end face is flush with the end face of the copper bar and the end face of the rotor core, and ensure that its inner ring is tightly fitted with the copper bar and the rotor core; start the heating function of the fixed heating fixture 5, and use electromagnetic induction heating to preheat the copper ring, copper bar and rotor core waiting for welding on the other end face. The heating temperature of the fixed heating fixture 5 is 320°C, and the heating rate is 20°C / s. After heating to the set temperature, keep it for 20s and stop heating;

[0065] (6) The preheated copper bars, the outer periphery of the rotor core and the inner ring of the copper ring are welded by friction stir welding. The rotation speed during welding is 560 rpm, the feed speed is 280 mm / min, and the inclination angle of the main shaft is 2.5°. After welding for one circle, i.e. 360°, the retraction operation is started: the stirring needle 401 rotates synchronously with the shaft shoulder 402 and moves upward relative to the shaft shoulder 402. At this time, the stirring needle 401 and the shaft shoulder 402 rotate synchronously at a speed of 560 rpm, and continue to move along the circumference at 280 mm / min. At the same time, the stirring needle 401 is driven by an external motor and moves upward relative to the shaft shoulder 402 at a speed of 15 mm / min until the lower end surface of the stirring needle 401 is flush with the lower end surface of the shaft shoulder 402, completing the retraction operation, thereby eliminating the tail hole at the welding end surface;

[0066] (7) The stirring tool is replaced with a three-edge milling cutter, and the two end rings 3 after welding are milled according to the requirements of the drawing. The tool rotation speed during milling is 9500 rpm, and the feed speed is 280 mm / min. The excess part is removed to achieve the final forming of the part and complete the entire processing process.

[0067] Comparative Example 1

[0068] This comparative example is basically the same as Example 1, except that the retraction-type friction stir welding technology is not used, that is, after the welding is completed, there is no relative movement between the stirring needle 401 and the shaft shoulder 402, and the two leave the weld together, leaving a tail hole on the weld.

[0069] Due to the lack of material at the tail hole, the mechanical properties of this area are reduced and the sealing is poor, which has an adverse effect on the performance of the product. The existence of the tail hole will also weaken the structural strength and conductivity of the end ring, thereby reducing the quality and service life of the product.

[0070] Comparative Example 2

[0071] This comparative example is basically the same as Example 1, except that the fixed heating fixture 5 is replaced by a common fixed fixture without heating function, and there is no preheating process for the material to be welded.

[0072] When the fixing fixture only has the fixing function but not the preheating function, the material does not undergo the preheating process and is therefore not softened. During welding, the upsetting force and forward tensile strength exerted on the stirring tool will be relatively large. On the one hand, this will reduce the life of the stirring tool. On the other hand, the feed speed during welding will also be reduced accordingly, affecting the welding production efficiency and reducing the quality of the weld to a certain extent.

[0073] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any technician familiar with the profession, without departing from the scope of the technical solution of the present invention, according to the technical essence of the present invention, any simple modification, equivalent replacement and improvement made to the above embodiment still falls within the protection scope of the technical solution of the present invention.

Claims

1. A motor rotor for new energy vehicles, characterized in that: It includes a rotor main core, a number of assembly strips and two end rings; The outer side wall of the rotor main core is provided with a plurality of reserved slot holes, and the assembly strip is fitted into the slot holes. The length of the assembly strip is the same as the length of the rotor main core. After the assembly strip is inserted into the slot hole, its head end and tail end are exposed and the head and tail end surfaces of the assembly strip are respectively flush with the upper and lower end surfaces of the rotor main core to form end circular surfaces; The end ring is a circular ring structure, the inner ring shape of the end ring is the same as the outer circumferential contour shape of the end circular surface formed after the rotor main core is assembled with the assembly strip, and the outer end surface of the end ring is flush with the end circular surface; The rotor main core, the assembly strip and the end ring are connected to each other through friction stir welding.

2. The motor rotor for new energy vehicles according to claim 1, characterized in that: The slot holes are symmetrically arranged with the axis of the rotor main core as the center line, and the shapes of the assembly strips and the slot holes are matched.

3. The motor rotor for new energy vehicles according to claim 1, characterized in that: The main core of the rotor is a rotor iron core, and the assembly strip is a copper strip.

4. The friction stir welding manufacturing method for a motor rotor for a new energy vehicle according to any one of claims 1 to 3, characterized in that: The following steps are involved: Step S1: Assemble the assembly strip and the rotor main core, insert the assembly strip into each slot hole respectively, and make the end surface of the assembly strip and the rotor main core flush; Step S2: disposing a first end ring outside one end of a whole formed by the rotor main core and the assembly strip, so that the outer end surface of the first end ring is flush with the end formed by the assembly strip and the rotor main core; Step S3: connecting the rotor main core and the assembly strip at this end to the first end ring by friction stir welding; Step S4: turning over the rotor main core, and setting the second end ring outside the other end of the whole formed by the rotor main core and the assembly strip, so that the outer end surface of the second end ring is flush with the other end formed by the assembly strip and the rotor main core; Step S5: connecting the rotor main core and the assembly strip at the other end to the second end ring by friction stir welding.

5. The friction stir welding manufacturing method for a motor rotor for a new energy vehicle according to claim 4, characterized in that: The rotor main core is clamped and positioned by a fixed heating fixture, and the clamping and fixing part of the fixed heating fixture is the outer side of the end of the rotor main core, the assembly strip and the end ring assembly; preheating treatment is performed before stir friction welding in step S3 and step S5.

6. The friction stir welding manufacturing method for a motor rotor for a new energy vehicle according to claim 4, characterized in that: The friction stir welding is a retraction type friction stir welding, specifically: After one round of welding along the connecting surface between the integral body formed by the rotor main core and the assembly strip and the end ring, the retraction operation begins; during the retraction operation, the stirring needle rotates synchronously with the shaft shoulder while the stirring needle moves upward relative to the shaft shoulder until the lower end surface of the stirring needle is flush with the lower end surface of the shaft shoulder, completing the retraction operation to eliminate the tail hole at the weld end surface.

7. The friction stir welding method for manufacturing a motor rotor for a new energy vehicle according to claim 4, characterized in that: The welding feed speed of the friction stir welding is 100-3000 mm / min, the rotation speed of the stirring needle is 400-8000 rpm, and the inclination angle of the main shaft is 2-4°.

8. The friction stir welding manufacturing method for a motor rotor for a new energy vehicle according to claim 4, characterized in that: When friction stir welding is performed with a retraction operation, the speed at which the stirring needle moves upward relative to the shaft shoulder is 10-20 mm / min.

9. The friction stir welding manufacturing method for a motor rotor for a new energy vehicle according to claim 5, characterized in that: The heating temperature of the fixed heating fixture is 300-400°C, the heating speed is 10-40°C / s, and the temperature is kept at the predetermined temperature for 15-30s.

10. The friction stir welding manufacturing method for a motor rotor for a new energy vehicle according to claim 4, characterized in that: The upsetting force during friction stir welding is 5000N-11000N, and the welding depth is 4-10mm; friction stir welding adopts constant pressure control method.

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