Method of manufacturing motor case

Abstract

To provide a motor case capable of preventing rotation of a rotor from decentering.SOLUTION: A motor case comprises a case body and a cover part capable of fitting with the case body. The case body comprises a case body first surface and a case body second surface. The cover part comprises a cover part first surface and a cover part second surface. A method of manufacturing the case body comprises the steps of: fixing the case body to a case body cutting device; machining the case body first surface using a case body first cutter; machining the case body second surface using a case body second cutter; and removing the machined case body from the case body cutting device. A method of manufacturing the cover part comprises the steps of: fixing the cover part to a cover part cutting device; machining the cover part first surface using a cover part first cutter; machining the cover part second surface using a cover part second cutter; and removing the machined cover part from the cover part cutting device.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a method for manufacturing a motor case. [Background technology]

[0002] A motor case is known that includes a case body configured to house a stator, a rotor, and a rotor shaft, and a cover configured to be fitted to the case body. Related technology is disclosed in Patent Document 1. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2004-260893 Summary of the Invention [Problem to be solved by the invention]

[0004] The case body has a case body first surface that can be fitted with the stator, and a case body second surface that can be fitted with the cover. The cover has a cover part first surface that can support the rotor shaft, and a cover part second surface that can be fitted with the case body second surface. All of these surfaces have a cylindrical shape centered on the rotation axis of the rotor. If at least a portion of these surfaces is misaligned from the rotation axis, eccentricity will occur in the rotation of the rotor, which is a problem as it can cause vibrations and noise. [Means for solving the problem]

[0005] In the content of claim 1, the order of the step of processing the first surface of the case body and the step of processing the second surface of the case body is not particularly limited. The second surface of the case body may be processed first, or the first surface of the case body and the second surface of the case body may be processed simultaneously. Similarly, the order of the step of processing the first surface of the cover and the step of processing the second surface of the cover is not particularly limited.

[0006] According to the configuration of claim 1, the first and second case body surfaces can be machined using the same device. This allows for improved coaxiality between the two surfaces compared to when the two surfaces are machined using different devices. Furthermore, the first and second case body surfaces can be machined continuously while the case body is fixed. Because the two surfaces can be machined without any misalignment, this allows for improved coaxiality between the two surfaces. This prevents eccentricity from occurring in the rotor rotation. Similarly, the first and second cover surface surfaces can be machined using the same device. Furthermore, the first and second cover surface surfaces can be machined continuously while the cover is fixed. This allows for improved coaxiality between the two surfaces. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a motor 1. [Figure 2] 3 is a schematic cross-sectional view of a first cover part cutting device 50. FIG. [Figure 3] FIG. 2 is a schematic cross-sectional view of a case body cutting device 60. DETAILED DESCRIPTION OF THE INVENTION

[0008] (Motor 1 configuration) FIG. 1 is a cross-sectional view showing the schematic configuration of a motor 1 according to this embodiment. FIG. 1 is a cross-sectional view taken along a plane passing through the rotation axis RA. In FIG. 1, the direction of the rotation axis RA is the x-direction. The motor 1 mainly comprises a motor case 2, a stator 3, a rotor 4, and a shaft 5. The motor case 2 has a three-piece structure including a case main body 10, a first cover part 20, and a second cover part 30. The first cover part 20 is also called a motor cover. The second cover part 30 forms a boundary with a gear mechanism (not shown), and is also called a gear-side cover. The case main body 10, the first cover part 20, and the second cover part 30 may be cast metal.

[0009] The case body 10 is a component configured to house the stator 3 and the rotor 4. The case body 10 has a cylindrical shape centered on the rotation axis RA, with ends in the ±x direction open. The case body 10 has a case body first surface 10p1 and a case body second surface 10p2. The case body first surface 10p1 is a surface that can be fitted to the stator 3 by shrink fitting, and is also a surface that can be fitted to the cover portion second surface 30p2 of the second cover portion 30 by fitting. The case body second surface 10p2 is a surface that can be fitted to the cover portion second surface 20p2 of the first cover portion 20 by fitting. The case body first surface 10p1 and the case body second surface 10p2 are surfaces that have a cylindrical shape centered on the rotation axis RA. The case body first surface 10p1 is formed in a range A1 from an end surface 10e1 of the case body 10 in the +x direction to the boundary surface BP. The case body second surface 10p2 is formed in a range A2 from the end surface 10e2 in the -x direction of the case body 10 to the boundary surface BP. The radius R1 of the case body first surface 10p1 relative to the rotation axis RA is smaller than the radius R2 of the case body second surface 10p2 relative to the rotation axis RA.

[0010] The stator 3 is shrink-fitted to the case body first surface 10p1. The rotor 4 is disposed inside the stator 3 so as to be rotatable around a rotation axis RA. A shaft 5 is fixed to the rotor 4. The central axis of the shaft 5 is coaxial with the rotation axis RA of the rotor 4.

[0011] The first cover portion 20 is a member that closes the opening surface of the case body 10 on the −x-direction side. The first cover portion 20 includes a cover portion first surface 20p1 and a cover portion second surface 20p2. The cover portion first surface 20p1 is a cylindrical surface having an inner radius R3 relative to the rotation axis RA. The cover portion second surface 20p2 is a cylindrical surface having a radius R2 relative to the rotation axis RA. The cover portion first surface 20p1 is formed on the inner wall of a shaft hole through which the shaft 5 passes, and is a surface that can support the shaft 5 for rotation about the rotation axis RA. Specifically, the cover portion first surface 20p1 supports the shaft 5 via a bearing 21. The cover portion second surface 20p2 is a surface that can be fitted with the case body second surface 10p2 of the case body 10. The radius R2 of the cover portion second surface 20p2 relative to the rotation axis RA is substantially the same as the radius R2 of the case main body second surface 10p2 relative to the rotation axis RA.

[0012] The second cover portion 30 is a member that closes the opening surface of the case body 10 on the +x-direction side. The second cover portion 30 includes a cover portion first surface 30p1 and a cover portion second surface 30p2. The cover portion first surface 30p1 is a cylindrical surface having an inner radius R3 relative to the rotation axis RA. The cover portion second surface 30p2 is a cylindrical surface having a radius R1 relative to the rotation axis RA. The cover portion first surface 30p1 is formed on the inner wall of a shaft hole through which the shaft 5 passes, and is a surface that can support the shaft 5 for rotation about the rotation axis RA. Specifically, the cover portion first surface 30p1 supports the shaft 5 via a bearing 31. The cover portion second surface 30p2 is a surface that can be fitted with the case body first surface 10p1 of the case body 10.

[0013] The first cover part 20 is assembled to the end part of the case body 10 in the -x direction by a spigot or a light press fit. As a result, the rotation axis RA of the first cover part 20 and the rotation axis RA of the case body 10 are aligned by the spigot. Similarly, the second cover part 30 is assembled to the end part of the case body 10 in the +x direction by a spigot or a light press fit. As a result, the rotation axis RA of the second cover part 30 and the rotation axis RA of the case body 10 are aligned by the spigot.

[0014] (Configuration of first cover portion cutting device 50) 2 shows a schematic cross-sectional view of the first cover part cutting device 50. The first cover part cutting device 50 is a boring device for performing inner diameter boring on the cover part first surface 20p1 of the first cover part 20 and for performing outer diameter boring on the cover part second surface 20p2. Because the boring device is a general processing device, detailed explanation will be omitted and only the content relevant to the technology of this specification will be explained.

[0015] The first cover part cutting device 50 mainly comprises a work table 51, a workpiece fixing unit 52, a motor 53, a shaft 54, and a shaft head 55. The workpiece fixing unit 52 is fixed onto the work table 51. The workpiece fixing unit 52 is configured to be able to fix the first cover part 20. The shaft 54 ​​and the shaft head 55 are configured to be rotatable around a rotation axis RA2 by the motor 53. The shaft 54 ​​and the shaft head 55 are also configured to be movable in the ±x directions by a movement mechanism (not shown).

[0016] A first cutting tool 57 and a second cutting tool 58 are fixed to the axial head 55. That is, the relative positions of the first cutting tool 57 and the second cutting tool 58 are fixed. A cutting edge 57e of the first cutting tool 57 is disposed at a position of an inner radius R3 from the rotation axis RA2. This allows the cover portion first surface 20p1 to be fine-bored by the rotation trajectory of the cutting edge 57e. A cutting edge 58e of the second cutting tool 58 is disposed at a position of a radius R2 from the rotation axis RA2. This allows the cover portion second surface 20p2 to be fine-bored by the rotation trajectory of the cutting edge 58e.

[0017] Cutting edges 57e and 58e are spaced apart by a distance D1 in the x direction. Specifically, cutting edge 57e protrudes by the distance D1 toward first cover part 20 (negative x direction) relative to cutting edge 58e. Distance D1 is greater than thickness T1 of first cover part 20 in the x direction.

[0018] There is also a second cover part cutting device for boring the first cover part surface 30p1 and the second cover part surface 30p2 of the second cover part 30. However, the details of the second cover part cutting device are similar to those of the first cover part cutting device 50 described above, and therefore a description thereof will be omitted here.

[0019] (Configuration of case body cutting device 60) 3 shows a schematic cross-sectional view of the case body cutting device 60. The case body cutting device 60 is a boring device for performing inner diameter boring on the case body first surface 10p1 and the case body second surface 10p2 of the case body 10. The case body cutting device 60 mainly comprises a work table 61, a workpiece fixing unit 62, a prime mover 63, a shaft 64, and a shaft head 65. The respective components of the work table 61-shaft head 65 of the case body cutting device 60 are the same as the respective components of the work table 51-shaft head 55 of the first cover part cutting device 50 described above, and therefore description thereof will be omitted.

[0020] A first cutting tool 67 and a second cutting tool 68 are fixed to the shaft head 65. A cutting edge 67e of the first cutting tool 67 is disposed at a position of radius R1 from the rotation axis RA3. This allows the rotational trajectory of the cutting edge 67e to perform fine boring on the case body first surface 10p1. A cutting edge 68e of the second cutting tool 68 is disposed at a position of radius R2 from the rotation axis RA3. This allows the rotational trajectory of the cutting edge 68e to perform fine boring on the case body second surface 10p2.

[0021] Cutting edges 67e and 68e are spaced apart by a distance D2 in the x direction. Specifically, cutting edge 67e protrudes by the distance D2 toward case body 10 (+x direction) relative to cutting edge 68e. Distance D2 is greater than thickness T2 of case body 10 in the x direction.

[0022] (Manufacturing process of the first cover part 20) The first cover part 20, whose first cover part surface 20p1 and second cover part surface 20p2 have been roughly machined, is prepared. First, a step of fixing the first cover part 20 to the workpiece fixing unit 52 of the first cover part cutting device 50 is performed.

[0023] Next, the step of fine boring the cover portion first surface 20p1 is performed. This will be explained in detail. In the state shown in FIG. 2, the prime mover 53 is operated to rotate the axial head 55 around the rotation axis RA2. Then, a moving mechanism (not shown) moves the axial head 55 toward the first cover portion 20 (toward the -x direction) at a predetermined feed rate. Because the cutting edge 57e protrudes a distance D1 from the cutting edge 58e, the cutting edge 57e contacts the cover portion first surface 20p1 before the cutting edge 58e. Therefore, the fine boring of the cover portion first surface 20p1 is performed first. Then, when the cutting edge 57e moves toward the -x direction from the end surface 20f of the first cover portion 20, the fine boring of the cover portion first surface 20p1 is completed.

[0024] The distance D1 between the cutting edges 57e and 58e is set to be larger than the thickness T1 of the first cover portion 20. Therefore, when the fine boring of the cover portion first surface 20p1 is completed, the cutting edge 58e has not yet reached the cover portion second surface 20p2, and the fine boring of the cover portion second surface 20p2 has not yet started.

[0025] Next, the step of fine boring the second cover surface 20p2 is performed. Specifically, after the fine boring of the first cover surface 20p1 is completed, the shaft head 55 is further moved in the -x direction, and the cutting edge 58e comes into contact with the second cover surface 20p2. Therefore, the fine boring of the second cover surface 20p2 begins.

[0026] When the fine boring of the cover portion second surface 20p2 is completed, the axial head 55 moves in a direction (+x direction) away from the first cover portion 20, and the prime mover 53 is stopped. Then, a step of removing the machined first cover portion 20 from the workpiece fixing unit 52 is performed.

[0027] There is also a manufacturing process for the second cover portion 30. However, since the manufacturing process for the second cover portion 30 is similar to the manufacturing process for the first cover portion 20 described above, a description thereof will be omitted here.

[0028] (Manufacturing process of the case body 10) The case body 10, whose first and second surfaces 10p1, 10p2 have been roughly machined, is prepared. First, the step of fixing the case body 10 to the workpiece fixing unit 62 of the case body cutting device 60 is carried out.

[0029] Next, the step of fine boring the case body first surface 10p1 is performed. A more detailed explanation follows. In the state shown in FIG. 3, the prime mover 63 is operated to rotate the axial head 65 around the rotation axis RA3. Then, a moving mechanism (not shown) moves the axial head 65 toward the case body 10 (the +x direction) at a predetermined feed rate. Because the cutting edge 67e protrudes a distance D2 from the cutting edge 68e, the cutting edge 67e contacts the case body first surface 10p1 before the cutting edge 68e. Therefore, the fine boring of the case body first surface 10p1 is performed first.

[0030] After the fine boring of the case body first surface 10p1 is completed, the axial head 65 is further moved in the +x direction, and the cutting edge 68e comes into contact with the case body second surface 10p2. Thus, the fine boring of the case body second surface 10p2 begins. When the fine boring of the case body second surface 10p2 is completed, the axial head 65 moves in the direction away from the case body 10 (-x direction), and the motor 63 is stopped. Then, the process of removing the machined case body 10 from the workpiece fixing unit 62 is performed.

[0031] (effect) The case body first surface 10p1 of the case body 10 ensures coaxiality with the stator 3. The case body second surface 10p2 of the case body 10 also ensures coaxiality with the cover portion first surface 20p1 of the first cover portion 20 (i.e., coaxiality with the rotor 4). If the case body first surface 10p1 and the case body second surface 10p2 are not coaxial (i.e., if the centers of the cylindrical shapes of each surface are not aligned with the rotation axis RA), eccentricity occurs in the rotation of the rotor 4. This is problematic because it causes vibration and noise. Therefore, the technology described herein allows the two surfaces, the case body first surface 10p1 and the case body second surface 10p2, to be machined using a first cutting tool 67 and a second cutting tool 68 fixed to a single axial head 65 (i.e., using the same machine). This improves the coaxiality between the two surfaces compared to machining the two surfaces using two axial heads (i.e., using different machines). Furthermore, with the case body 10 fixed to the workpiece fixing unit 62, the case body first surface 10p1 and the case body second surface 10p2 can be machined continuously. Since the two surfaces can be machined without any misalignment, it is possible to improve the coaxiality between the two surfaces. As a result, it is possible to prevent eccentricity from occurring in the rotation of the rotor 4.

[0032] Furthermore, the first cover surface 20p1 of the first cover portion 20 ensures coaxiality with the rotor 4. The second cover surface 20p2 of the first cover portion 20 ensures coaxiality with the case body 10. The technology described herein allows the first cover surface 20p1 and the second cover surface 20p2 to be machined using the first cutting tool 57 and the second cutting tool 58 fixed to the same axial head 55 (i.e., using the same device), thereby improving the coaxiality between the two surfaces. Furthermore, the first cover surface 20p1 and the second cover surface 20p2 can be machined continuously while the first cover portion 20 is fixed to the workpiece fixing unit 52. Since the two surfaces can be machined without any misalignment, the coaxiality between the two surfaces can be improved. As a result, it is possible to prevent eccentricity from occurring in the rotation of the rotor 4.

[0033] Similarly, the first cover surface 30p1 and the second cover surface 30p2 of the second cover portion 30 can be machined using the same device and can be machined continuously with a single fixation, thereby improving the coaxiality between the two surfaces.

[0034] (Variation) The structure of the motor case 2 is not limited to that of this embodiment and may be various. For example, the motor case may have a two-piece structure including a case main body with an integrated gear case and a motor cover. [Explanation of symbols]

[0035] 1: Motor 2: Motor case 3: Stator 4: Rotor 5: Shaft 10: Case body 10p1: Case body first surface 10p2: Case body second surface 20: First cover part 20p1: Cover part first surface 20p2: Cover part second surface 30: Second cover part 30p1: Cover part first surface 30p2: Cover part second surface 50: First cover part cutting device 52: Workpiece fixing unit 57: First cutting tool 58: Second cutting tool 60: Case body cutting device 62: Workpiece fixing unit 67: First cutting tool 68: Second cutting tool

Claims

[Claim 1] A method for manufacturing a motor case, the motor case includes a case main body configured to be able to store a stator, a rotor, and a rotor shaft, and a cover portion configured to be able to be fitted with the case main body, The case body includes: a case main body first surface that can be fitted with the stator by fitting, the case main body first surface having a cylindrical shape centered on a rotation axis of the rotor; a case main body second surface that can be fitted with the cover portion by fitting, the case main body second surface having a cylindrical shape centered on the rotation axis; It is equipped with The cover portion is a cover first surface capable of supporting the rotor shaft that rotates around the rotation axis, the cover first surface having a cylindrical shape centered on the rotation axis; a cover portion second surface that can be fitted with the case main body second surface and has a cylindrical shape centered on the rotation axis; It is equipped with The manufacturing process of the case body includes: a step of fixing the case body to a case body cutting device including a case body first blade and a case body second blade rotatable around the rotation axis; machining the case body first surface with the case body first cutting tool; a step of machining the second surface of the case body with the second cutter; removing the processed case body from the case body cutting device; It is equipped with The manufacturing process of the cover portion includes: a step of fixing the cover portion to a cover portion cutting device including a first cover portion cutting blade and a second cover portion cutting blade rotatable around the rotation axis; a step of machining the cover portion first surface with the cover portion first blade; machining the cover portion second surface with the cover portion second blade; removing the machined cover from the cover cutting device; Equipped with Manufacturing method of motor case.

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