Motor housing, method of manufacturing motor housing and motor

Abstract

To provide a manufacturing method capable of improving a surface strength in a die-cast motor housing.SOLUTION: A motor housing 5 comprises a cylindrical main body part 51 and the main body part includes a parting line, which protrudes outwards and extends in an axial direction, on an outer peripheral surface. The main body part includes a modification part 63, in which a material tissue is modified, in at least a portion on the outer peripheral surface in contact with the parting line.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a motor housing, a method for manufacturing a motor housing, and a motor. [Background technology]

[0002] Die-cast motor housings are known. The motor housings are manufactured using a die-casting machine. Patent Document 1, for example, discloses a die-casting machine that includes a plunger sleeve to which molten metal is supplied via a supply port, a mold connected to the plunger sleeve, a plunger that injects the molten metal supplied to the plunger sleeve into the mold, and a controller that controls the operation of the plunger. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2021-133392 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that in die-casting machines, the molten metal supplied to the plunger sleeve is rapidly cooled and solidified upon contact with the plunger sleeve, resulting in the formation of a chill layer on the inner surface of the plunger sleeve. The chill layer is broken up by the tip of the plunger, forming a fractured chill layer. It is known that the fractured chill layer may not remelt but may be mixed into the molten metal as it fills the mold, resulting in the inside of the die-cast product.

[0005] The fractured chill layer is difficult to bond with the molten metal, and therefore reduces physical properties such as tensile strength and elongation starting from the interface with the molten metal. Therefore, if the fractured chill layer is exposed on the surface of a die-cast product, it can be a major factor in reducing the strength and pressure resistance of the die-cast product. Therefore, a method for improving the surface strength of the die-cast product is needed.

[0006] An object of the present invention is to provide a manufacturing method that can improve the surface strength of a die-cast motor housing. [Means for solving the problem]

[0007] A motor housing according to one embodiment of the present invention is a die-cast motor housing having a cylindrical main body portion with a parting line on an outer peripheral surface that protrudes outward and extends in the axial direction, and the main body portion has a modified portion in which the material structure is modified, at least in a portion above the parting line.

[0008] A method for manufacturing a motor housing according to one embodiment of the present invention is a method for manufacturing a die-cast motor housing having a cylindrical main body, which includes a forming step of injecting molten metal through a gate into a cavity formed by multiple molds to form a die-cast product that will serve as the main body, a dividing step of dividing the die-cast product and a runner at the gate, and a modifying step of performing a modification treatment on the gate portion of the die-cast product that is the boundary between the die-cast product and the runner formed by the dividing step to modify the material structure.

[0009] A motor according to one embodiment of the present invention includes a rotor, a stator positioned radially outward from the rotor, and a housing that is in contact with the stator on the outer periphery of the stator. The housing is the die-cast motor housing. [Effects of the Invention]

[0010] According to one embodiment of the present invention, a method for manufacturing a motor housing having improved surface strength can be provided. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a cross-sectional view showing a schematic configuration of a motor according to a first embodiment. [Figure 2] FIG. 2 is a side view of the motor housing showing a schematic configuration of the motor housing. [Figure 3] FIG. 3 is a cross-sectional view of the motor housing as viewed in the axial direction of the motor. [Figure 4] FIG. 4 is a partially enlarged view of FIG. [Figure 5] FIG. 5 is a perspective view showing a schematic configuration of a friction stir tool. [Figure 6] FIG. 6 is a diagram illustrating the friction stir treatment. [Figure 7] FIG. 7 is a diagram schematically showing a state in which the friction stir pin of the friction stir tool is pressed into the material to be modified. [Figure 8] FIG. 8 is a top view showing how the friction stir tool is moved along the surface of the material to be modified. [Figure 9] FIG. 9 is a diagram showing an example of the configuration of a die of a die-casting machine. [Figure 10] FIG. 10 is a diagram showing a state in which the fractured chill layer remains around the gate. [Figure 11] FIG. 11 is a diagram illustrating the die-cast product removed from the die-casting machine. [Figure 12] FIG. 12 is a diagram illustrating the division step. [Figure 13] FIG. 13 is a diagram showing how the rotary tool is pressed against the gate portion. [Figure 14] FIG. 14 is a diagram showing the state in which the gate portion has been modified. [Figure 15] FIG. 15 is a view equivalent to FIG. 4 of a motor housing according to a modified example of the first embodiment. [Figure 16]FIG. 16 is a diagram illustrating a modification process according to another embodiment. [Figure 17] FIG. 17 is a diagram showing how the rotary tool is pressed against the gate portion. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the drawings. The same or corresponding parts in the drawings are designated by the same reference numerals, and their description will not be repeated. Furthermore, the dimensions of the components in each drawing do not faithfully represent the actual dimensions of the components and the dimensional ratios of the components.

[0013] Furthermore, in the following description, the expressions "fix," "connect," and "attach" (hereinafter referred to as "fixing") include not only cases where members are directly fixed to each other, but also cases where members are fixed via other members. In other words, in the following description, the expression "fixing" includes both direct and indirect fixing of members to each other.

[0014] In the following description, a direction parallel to the central axis P of the shaft 4 will be referred to as the axial direction X, and a direction perpendicular to the central axis P will be referred to as the radial direction.

[0015] (Embodiment 1) (Motor configuration) A motor 1 according to a first exemplary embodiment of the present invention will be described with reference to Fig. 1. As shown in Fig. 1, the motor 1 has a rotor 2, a stator 3, a shaft 4, and a motor housing 5. The rotor 2 rotates around a central axis P relative to the stator 3. In this embodiment, the motor 1 is a so-called inner rotor type motor in which the rotor 2 is positioned inside the cylindrical stator 3 so as to be rotatable around the central axis P.

[0016] The rotor 2 includes a rotor core 21 and a magnet 22. The rotor 2 is located radially inward of the stator 3 and is rotatable relative to the stator 3 about a central axis P.

[0017] The rotor 2 has a shaft insertion hole 2a extending along the central axis P. The shaft 4 is fixed to the rotor 2 while passing through the shaft insertion hole 2a in the axial direction. This allows the rotor 2 to rotate together with the shaft 4. The configuration of the rotor 2 is similar to that of a general rotor, and therefore a detailed description of the configuration will be omitted.

[0018] The stator 3 is cylindrical. The rotor 2 is located radially inward of the stator 3. That is, the stator 3 is located radially outward of the rotor 2. In this embodiment, the stator 3 is shrink-fitted to the inside of the motor housing 5. The stator 3 includes a stator core 31 and a stator coil 32. The stator coil 32 is wound around the stator core 31. The configuration of the stator 3 is similar to that of a general stator, and therefore a detailed description of the configuration will be omitted.

[0019] The motor housing 5 accommodates the rotor 2, the stator 3, and the shaft 4. More specifically, the motor housing 5 is located on the outer periphery of the stator 3, which is shrink-fitted to the inside of the motor housing 5. The motor housing 5 is in contact with the stator 3.

[0020] The motor housing 5 is manufactured by injection molding using a die-casting machine 8 that manufactures die-cast products. That is, the motor housing 5 is made of die-cast material. The motor housing 5 is made of a material such as an aluminum alloy. Details of the die-casting machine 8 and the manufacturing method of the motor housing 5 will be described later.

[0021] (Motor housing configuration) As shown in FIGS. 2 and 3 , the motor housing 5 has a cylindrical main body 51. In this specification, cylindrical refers to a shape having an internal space extending in the axial direction X. That is, the inner and outer circumferential surfaces of the main body 51 may each have a circular or polygonal shape when viewed in the axial direction. The main body 51 may have a portion that protrudes radially outward or inward. The main body 51 does not have to have a uniform shape in the axial direction X. The shape of the main body 51 when viewed in the axial direction X does not have to be rotationally symmetric. The main body 51 may have an end face that covers at least one of one or the other axial ends.

[0022] The main body 51 has, on its outer circumferential surface, a parting line 61 that protrudes radially outward and a protrusion 62 that protrudes radially outward. The parting line 61 is a parting line that is formed on the surface of a typical die-cast molded product. The parting line is formed, for example, by a narrow gap that occurs between the mating surfaces of multiple molds that are butted together in a die-casting device that produces die-cast molded products.

[0023] In this embodiment, the parting line 61 includes a one-side parting line 611 and an other-side parting line 612. The one-side parting line 611 extends in the axial direction from one end of the motor housing 5 in the axial direction X toward the center of the motor housing 5 in the axial direction. The other-side parting line 612 extends in the axial direction from the other end of the motor housing 5 in the axial direction X toward the center of the motor housing 5 in the axial direction. The one-side parting line 611 and the other-side parting line 612 are aligned in the axial direction X.

[0024] As shown in FIG. 4, in this embodiment, the height of the parting line 61 in the protruding direction is L2. Generally, the gap between the mating surfaces of multiple molds is small. Therefore, the parting line is formed by a narrow linear protrusion. The width of the parting line is the length in a direction intersecting the direction in which the parting line extends. Hereinafter, the width direction Y of the parting line 61 means the direction intersecting the direction in which the parting line 61 extends.

[0025] 2, the protruding portion 62 is in contact with the parting line 61. More specifically, the protruding portion 62 is located between a parting line 611 on one side and a parting line 612 on the other side.

[0026] In this embodiment, the width of the protruding tip surface 62a of the protruding portion 62 is wider than the width of the parting line 61. For the sake of explanation, in Fig. 2, the protruding tip surface 62a of the protruding portion 62 is indicated by diagonal lines.

[0027] Generally, die-cast products formed by a die-casting machine are separated from the runner at a gate. Furthermore, die-cast products are separated from the overflow portion, which is a discharge passage for molten metal, at an overflow gate. Therefore, in die-cast products, protrusions are formed at the parting line as traces of the gate and overflow gate. Furthermore, the surface of the protrusion exposes a separation surface formed by separation from the runner and overflow portion.

[0028] The protrusion 62 in contact with the parting line 61 of the motor housing 5 is located at the position where the gate or overflow gate was located. Note that, hereinafter, the gate and overflow gate will be simply referred to as the gate.

[0029] The shape of the protrusion 62 is determined by the configuration of the mold used to manufacture the motor housing 5. In this embodiment, as shown in Figures 3 and 4, the shape of the protrusion 62 is a trapezoid whose length in the width direction Y decreases as it extends radially outward.

[0030] In this embodiment, the protrusion 62 has a protruding height L1 in the protruding direction. In this embodiment, the material structure of the protruding tip surface 62a of the protruding portion 62 is modified. Therefore, in the main body 51, the material structure at the position where the gate was located is modified. In other words, in the motor housing 5, the dividing surface is not exposed at the protruding tip surface 62a of the protruding portion 62. Hereinafter, the portion of the motor housing 5 where the material structure is modified will be referred to as the modified portion 63.

[0031] As shown in Fig. 4, when viewed in the axial direction X, the modified portion 63 has a depth toward the inside of the main body portion 51. As shown in Figs. 2 and 4, in this embodiment, the dimension of the modified portion 63 in the width direction Y decreases toward the radially inward direction. The dimension of the radially outer side 63a of the modified portion 63 in the width direction Y matches the dimension of the protruding tip surface 62a of the protruding portion 62 in the width direction Y.

[0032] 2, the length in the axial direction X of the radially outer side 63a of the modified portion 63 is the same as the length in the axial direction X of the protrusion tip surface 62a of the protrusion 62. That is, in this embodiment, the material structure of the entire protrusion tip surface 62a of the protrusion 62 is modified.

[0033] As described above, the protruding portion 62 is in contact with the parting line 61. Therefore, the modified portion 63 is in contact with the parting line 61. The protruding portion 62 is located at the position where the gate was located. Therefore, the modified portion 63 being in contact with the parting line 61 also includes the case where a part of the dividing surface of the gate is located between the modified portion 63 and the parting line 61.

[0034] As shown in FIG. 4, in this embodiment, the depth L1 of the modified portion 63 is shorter than half the height L2 of the parting line 61 in the protruding direction.

[0035] The modified portion 63 is obtained by melting and solidifying the material that constitutes the main body portion 51, thereby performing a process that densifies the material structure. Therefore, the modified portion 63 has a material structure that is denser than the material structure that constitutes the main body portion 51. The process includes, for example, friction stir processing, laser welding, and the like. In this embodiment, the modified portion 63 is formed by friction stir processing the material that constitutes the main body portion 51. The friction stir processing will be described later.

[0036] When manufacturing die-cast products, a fractured chill layer may be located at the gate, which is the boundary between the cavity and the runner. Therefore, the fractured chill layer may be exposed on the surface of the die-cast product. If the fractured chill layer is exposed on the surface of the die-cast product, it may be a major factor in reducing the strength and pressure resistance of the die-cast product.

[0037] In contrast, in the motor housing 5, the protruding tip surface 62a of the protruding portion 62 where the gate was located is modified. That is, in the motor housing 5, the portion where the fractured chill layer may be exposed on the surface is subjected to friction stir treatment. This improves the surface strength of the motor housing 5. Therefore, it is possible to obtain a motor housing 5 with improved surface strength.

[0038] (Motor housing manufacturing method) Next, a method for manufacturing the motor housing 5 according to the first exemplary embodiment of the present invention will be described with reference to FIGS.

[0039] First, friction stir processing will be briefly explained using Figures 5 to 8. Friction stir processing is a process in which a rotary tool T is pressed against the surface of the material to be modified W1, and the base material that constitutes the material to be modified W1 is softened and stirred by frictional heat. Pressing the rotary tool T causes the base material to undergo plastic flow. This densifies the material structure of the portion where friction stir processing has been performed, increasing its hardness. In other words, friction stir processing can modify the surface of the material to be modified W1, and can improve the surface strength of the material to be modified W1.

[0040] As shown in Fig. 5, the rotary tool T has a columnar rotating part T1 extending in the axial direction along the central axis Q, and a friction stir pin T2 extending in the axial direction and having one end in the axial direction supported by the rotating part T1. The rotating part T1 is connected to a rotating shaft of a friction stir mill (not shown). The rotating part T1 rotates around the rotating shaft.

[0041] The diameter of the friction stir pin T2 decreases from one end in the axial direction supported by the rotating part T1 to the other end. The friction stir pin T2 rotates together with the rotating part T1 around the rotation axis of the friction stir device.

[0042] For example, as shown in FIG. 6, the friction stir pin T2 is brought into contact with the region R of the target material W1 where friction stir processing is to be performed while rotating around the rotation axis. As a result, the portion of the target material W1 that the friction stir pin T2 contacts is softened by frictional heat with the friction stir pin T2. ​​Next, as shown in FIG. 7, the friction stir pin T2 is pressed into the target material W1 and moved along the region R as shown in FIG. 8. As a result, the region R of the target material W1 is friction stir processed. As a result, the material structure of the region R of the target material W1 is densified. In other words, the region R of the target material W1 is modified. In FIG. 7, the modified portion W2 of the target material W1 is indicated by a dot.

[0043] In the friction stir treatment using the rotary tool T, the shape of the modified portion can be changed by adjusting the rotation speed of the rotary tool T and the dimensions of the friction stir pin T2. ​​For example, the width can be increased by increasing the rotation speed. Also, the depth can be increased by increasing the axial length of the friction stir pin T2.

[0044] Next, a method for manufacturing the motor housing 5 according to the first embodiment will be described with reference to Figures 9 to 14. The method for manufacturing the motor housing 5 includes a forming step, a dividing step, and a modifying step.

[0045] In the forming process, a die-cast product 7 that will become the motor housing 5 is formed using a die-casting device 8. The die-casting device 8 is a device that manufactures the die-casting product 7 by injection molding. The die-casting product is formed by solidifying molten metal M injected into a cavity 82 of the die-casting device 8. The die-casting device 8 has a configuration similar to that of a general die-casting device, so a detailed description thereof will be omitted.

[0046] FIG. 9 shows an example of the configuration of a mold 81 of a die-casting device 8. As shown in FIG. 9, the mating surfaces 81a of the multiple molds 81 of the die-casting device 8 are butted against each other. By butting the mating surfaces 81a against each other, a cavity is formed through which molten metal M passes or is filled. In this specification, the cavity for molding the portion that will become the die-cast product 7 is referred to as a cavity 82. A runner 83 is defined between the cavity 82 and a supply port of the die-casting device 8 through which molten metal M is supplied. A gate 84 is defined as a boundary between the cavity 82 and the runner 83. An overflow portion 85 is defined as a boundary between the cavity 82 and a discharge port through which molten metal M is discharged from the cavity 82. An overflow gate 86 is defined as a boundary between the cavity 82 and the overflow portion 85.

[0047] Molten metal M that has passed through a runner 83 is filled into the cavity 82. The die-cast product 7 is formed by solidifying the molten metal M that has filled the cavity 82.

[0048] A fractured chill layer C may flow into the cavity 82. The fractured chill layer C that has flowed into the cavity 82 may remain around the gate 84. FIG. 10 schematically shows a state in which the fractured chill layer C remains around the gate 84.

[0049] Next, as shown in Figure 11, the die-cast product 7 formed in the cavity 82 is removed from the die-casting device 8. The removed die-cast product 7 has parting lines 61 formed at positions where the mating surfaces 81a of the multiple molds 81 were abutted against each other. The removed die-cast product 7 also has a molded product protrusion 71 extending radially outward from the outer circumferential surface. The molded product protrusion 71 is a portion where the molten metal M in the runner 83 has solidified and a portion where the molten metal M in the overflow portion 85 has solidified.

[0050] Next, as shown in Fig. 12, in the dividing step, the die-cast product 7 and the molded product protrusion 71 are divided. As a result, a dividing surface formed by dividing the die-cast product 7 from the runner 83 is exposed. Also, a dividing surface formed by dividing the die-cast product 7 from the overflow portion 85 is exposed. Hereinafter, the dividing surface of the die-cast product 7 exposed by dividing the die-cast product 7 from the runner 83 is referred to as a gate portion 72. The gate portion 72 is located at the position of the gate 84 of the mold 81. In other words, a protrusion 62 is formed where the gate was located.

[0051] Next, in the modification step, a modification treatment is performed on the gate portion 72 formed in the dividing step. In this embodiment, the modification treatment is performed by a friction stir process in which a rotary tool T is pressed against the gate portion 72. As a result, a modified portion 63 in the motor housing 5 is formed.

[0052] The friction stir treatment densifies the material structure, that is, it is possible to densify the material structure of the gate portion 72. This makes it possible to improve the surface strength of the portion where the gate portion 72 was located.

[0053] 13, the friction stir pin T2 of the rotary tool T is rotated and brought into contact with one end of the gate portion 72 in the axial direction X. Then, the friction stir pin T2 of the rotary tool T is pushed into the gate portion 72 and moved over the gate portion 72 toward the other end in the axial direction X.

[0054] In this embodiment, the modification step performs friction stir treatment on the gate portion 72 using a rotary tool T having a rotating part T1 with a diameter larger than the width of the gate portion 72. That is, the modification treatment is performed on the entire gate portion 72. This can further improve the surface strength of the motor housing 5.

[0055] In addition, in this embodiment, the axial length of the friction stir pin T2 of the rotary tool T is adjusted to a length that forms a modified portion 63 whose depth L1 is shorter than half the height L2 of the parting line 61 in the protruding direction.

[0056] This reduces the time required for the modification step, thereby improving the efficiency of the modification work.

[0057] 14, by performing friction stir processing on the gate portion 72, the fractured chill layer C located around the gate portion 72 is pulverized. This makes it possible to eliminate the fractured chill layer C extending from the gate portion 72 toward the inner circumferential surface of the motor housing 5. This makes it possible to prevent a decrease in the strength and pressure resistance of the motor housing 5.

[0058] As described above, the manufacturing method of the motor housing 5 according to the exemplary embodiment of the present invention is a manufacturing method of a die-cast motor housing 5 having a cylindrical main body 51. The manufacturing method of the motor housing 5 includes a forming step of injecting molten metal M through gate 84 into cavity 82 formed by a plurality of molds 81 to form die-cast product 7 that will become main body 51, a dividing step of dividing die-cast product 7 and runner 83 at gate 84, and a modifying step of performing a modification treatment to modify the material structure of gate portion 72 of die-cast product 7 that is the boundary between die-cast product 7 and runner 83 formed in the dividing step.

[0059] In the die-cast product 7, the runner 83 is separated at the gate 84. Therefore, a fractured chill layer C may be exposed on the surface of the die-cast product 7 at the gate portion 72 formed by separation from the runner 83. If the fractured chill layer C is exposed on the surface of the die-cast product 7, it may be a factor that reduces the strength and pressure resistance of the die-cast product 7.

[0060] In contrast, in the motor housing manufacturing method, a modification process is performed to modify the material structure of the gate portion 72, which is the boundary with the runner 83, on the surface of the die-cast product 7. In other words, the motor housing 5 manufactured by the above-mentioned manufacturing method does not have the fracture chill layer C exposed on the surface. Therefore, a motor housing 5 with improved surface strength can be obtained.

[0061] In the present embodiment, the modification process is performed by a friction stir process in which the friction stir pin T2 of the rotary tool T is pressed into the gate portion 72.

[0062] This makes it possible to crush the broken chill layer C that has penetrated into the gate portion 72. Therefore, it is possible to obtain a motor housing 5 with improved internal strength.

[0063] The motor housing 5 manufactured by the above-described manufacturing method has a cylindrical main body 51, which is made by die-casting and has a parting line 61 on its outer circumferential surface that protrudes outward and extends in the axial direction. The main body 51 has a modified portion 63 in which the material structure is modified, on at least a portion of the outer circumferential surface that contacts the parting line 61.

[0064] When manufacturing a die-cast molded product, a fractured chill layer may be located at the gate, which is the boundary between the cavity and the runner. Therefore, the fractured chill layer may be exposed at the gate. If the fractured chill layer is exposed on the surface of the die-cast molded product, it may cause a decrease in the strength and pressure resistance of the die-cast molded product.

[0065] In contrast, the main body 51 of the motor housing 5 has a modified region 63 on a portion of its outer circumferential surface that contacts the parting line 61. The modified region 63 is located at the position of a gate 84 adjacent to the mating surface 81a of the multiple molds 81 that form the parting line 61. That is, in the motor housing 5, the gate region 72, where the fractured chill layer C may be exposed, is subjected to friction stir processing. As a result, even if the fractured chill layer C is exposed on the surface of the gate region 72, the fractured chill layer C is pulverized. This makes it possible to obtain a motor housing 5 with improved surface strength.

[0066] In this embodiment, the modified portion 63 is formed by friction stirring the material that constitutes the main body portion 51. Therefore, the modified portion 63 has a material structure that is denser than the material structure that constitutes the main body portion 51.

[0067] In the motor housing 5 in which the gate portion 72 has been friction-stirred, the fractured chill layer C that was present in the gate portion 72 has been pulverized. Therefore, it is possible to obtain a motor housing 5 with improved surface strength.

[0068] In this embodiment, the main body 51 has a protruding portion 62 that protrudes outward from the main body 51 on at least a portion of the outer circumferential surface that contacts the parting line 61. The protruding portion 62 is located at the position where the gate was located. The modified portion 63 is located over the entire protruding tip surface 62a of the protruding portion 62.

[0069] That is, in this embodiment, the modification treatment is performed on the entire gate portion 72. As a result, the surface strength of the entire portion of the motor housing 5 where the gate portion 72 was located is improved. Therefore, it is possible to obtain a motor housing 5 with improved surface strength.

[0070] In this embodiment, the modified portion 63 has a depth toward the inside of the main body portion 51. The depth L1 of the modified portion 63 in the protruding direction of the parting line 61 is shorter than half the protruding height L2 of the parting line 61.

[0071] The modified portion 63 having such a shape can be obtained, for example, by shortening the plunge depth of the friction stir pin T2. ​​In other words, it can be manufactured using a manufacturing method that requires a short time for the modification process. Therefore, it is possible to obtain a motor housing 5 with improved surface strength, which is manufactured using a manufacturing method with good work efficiency.

[0072] The motor 1 according to this embodiment also includes a rotating rotor 2, a stator 3 located radially outward from the rotor 2, and a motor housing 5 that is in contact with the stator 3 on the outer periphery of the stator 3. The motor housing 5 is a die-cast motor housing 5 manufactured by the above-described manufacturing method.

[0073] This makes it possible to obtain a motor 1 having a motor housing 5 with improved surface strength.

[0074] (Modification of the first embodiment) 15 is a view corresponding to FIG. 4 of a motor housing 105 according to a modification of embodiment 1. In the motor housing 105 according to this modification, the depth L1 of the modified portion 163 is greater than the depth L1 of the modified portion 63 of the motor housing 5 according to embodiment 1.

[0075] 15, the dimension in the width direction Y of the modified portion 163 of the motor housing 105 decreases radially inward. The dimension in the width direction Y of the radially outer side 163a of the modified portion 163 of the motor housing 105 matches the dimension in the width direction Y of the protruding tip surface 62a of the protruding portion 62.

[0076] The modified portion 163 of the motor housing 105 has a depth extending toward the inside of the main body portion 51. The depth L1 of the modified portion 163 in the protruding direction of the parting line 61 is longer than half the protruding height L2 of the parting line 61.

[0077] In this configuration, the modified area is larger than that of the motor housing 5 of embodiment 1. In other words, the strength is improved over a wide area radially inward from the area where the gate portion 72 was located. This makes it possible to obtain a motor housing 105 with improved surface strength.

[0078] (Other embodiments) Although the embodiments of the present invention have been described above, the above-described embodiments are merely examples for carrying out the present invention. Therefore, the present invention is not limited to the above-described embodiments, and it is possible to appropriately modify the above-described embodiments within the scope of the spirit of the present invention.

[0079] The shape of the protrusion 62 in each drawing is an example, and the shape of the protrusion may be the same as the shape of the gate of the die-casting machine.

[0080] The positional relationship between the one-side parting line 611, the other-side parting line 612, and the protrusion 62 in each drawing is an example. The positional relationship between the parting line and the protrusion is determined by the positional relationship between the mating surfaces of the molds in the die-casting machine and the gate. For example, the protrusion may be aligned in the width direction with respect to the one-side parting line and the other-side parting line.

[0081] In the first embodiment, the friction stir treatment is performed using a rotary tool T having a friction stir pin T2. ​​However, the friction stir treatment may also be performed using a rotary tool without a friction stir pin. For example, the rotary tool is rotated and the axial end face of the rotary tool is brought into contact with the gate portion. This allows the surface portion of the gate portion to undergo plastic flow. The gate portion can also be modified using such a tool.

[0082] In the first embodiment and the modified example of the first embodiment, the shape of the reforming section 63, 163 is trapezoidal when viewed in the axial direction of the motor housing 5, 105. However, the shape of the reforming section may be, for example, rectangular or another shape.

[0083] In the first embodiment and the modified example of the first embodiment, the shape of the radially outer side 63a, 163a of the modified portion 63, 163 coincides with the protruding tip surface 62a of the protruding portion 62. However, the shape of the radially outer side of the modified portion may be different from that of the protruding tip surface of the protruding portion. That is, the width dimension of the radially outer side of the modified portion may be smaller or larger than the width dimension of the protruding tip surface of the protruding portion. The axial length of the radially outer side of the modified portion may be shorter or longer than the axial length of the protruding tip surface of the protruding portion.

[0084] In the first embodiment and the modified example of the first embodiment, the modified portions 63, 163 are located on the protruding portions 62, 162 that protrude outward from the main body portion 51. However, the modified portions may be located on a flat portion that does not protrude from the main body portion.

[0085] In the modification step in the manufacturing method of the motor housing of the first embodiment, as shown in Fig. 16, the gate portion 73 formed on the overflow gate 86 side may also be modified as shown in Fig. 17. The gate portion 73 is a dividing surface formed at the position of the overflow gate 86 by dividing the die-cast product 7 and the overflow portion 85.

[0086] That is, the dividing step in this embodiment includes a step of dividing the die-cast product 7 and the overflow portion 85, which is a discharge passage for the molten metal M, by the overflow gate 86. The modifying step includes a step of performing a modifying treatment on the gate portion 73, which is the boundary between the die-cast product 7 formed by the dividing step and the overflow portion 85, in the die-cast product 7, to modify the material structure.

[0087] This improves the surface strength of the motor housing 5 even in the area where the gate portion 73, a trace of the overflow gate 86, was located. It also pulverizes the fractured chill layer C located around the gate portion 73. This prevents the strength and pressure resistance of the motor housing 5 from decreasing.

[0088] (Configuration example) The present technology can also be configured as follows.

[0089] (1) The motor housing has a cylindrical main body portion, which is a die-cast motor housing having a parting line on its outer circumferential surface that protrudes outward and extends in the axial direction. The main body portion has a modified portion in which the material structure is modified on at least a portion of the outer circumferential surface that contacts the parting line.

[0090] (2) In the motor housing described in (1), the modified portion has a material structure that is denser than the material structure that constitutes the main body portion.

[0091] (3) In the motor housing described in (2), the main body has a protrusion that protrudes outward from the main body on at least a portion of the outer circumferential surface that contacts the parting line, and the modified portion is located over the entire protruding tip surface of the protrusion.

[0092] (4) In the motor housing according to any one of (1) to (3), the modified portion has a depth extending toward the inside of the main body portion, and the depth of the modified portion in the protruding direction of the parting line is shorter than half the protruding height of the parting line.

[0093] (5) In the motor housing according to any one of (1) to (3), the modified portion has a depth extending toward the inside of the main body portion, and the depth of the modified portion in the protruding direction of the parting line is longer than half the protruding height of the parting line.

[0094] (6) In the motor housing according to any one of (1) to (5), the modified portion is formed by friction stirring of the material that forms the main body portion.

[0095] (7) A method for manufacturing a motor housing made of die-cast metal having a cylindrical main body includes a forming step of forming a die-cast product that will become the main body by injecting molten metal through a gate into a cavity formed by multiple molds, a dividing step of dividing the die-cast product and a runner at the gate, and a modifying step of performing a modification treatment on the gate portion of the die-cast product that is the boundary between the die-cast product and the runner formed by the dividing step to modify the material structure.

[0096] (8) In the motor housing manufacturing method described in (7), the dividing step includes a step of dividing the die-cast molded product and an overflow portion, which is a discharge passage for molten metal, by an overflow gate, and the modifying step includes a step of performing a modifying treatment on the gate portion of the die-cast molded product, which is a boundary between the die-cast molded product and the overflow portion, formed by the dividing step, to modify the material structure.

[0097] (9) In the motor housing manufacturing method described in (7) or (8), the modification step performs the modification treatment by a friction stir treatment in which a rotary tool is pressed against the gate portion.

[0098] (10) In the motor housing manufacturing method according to any one of (7) to (9), the modification step performs modification treatment on the entire gate portion.

[0099] (11) In the motor housing manufacturing method described in any one of (7) to (10), in the modification step, the modification treatment is carried out by a friction stir treatment in which a friction stir pin of a rotary tool is pushed into the gate portion.

[0100] (12) A motor includes a rotating rotor, a stator positioned radially outward from the rotor, and a motor housing in contact with the stator on the outer periphery of the stator, the motor housing being a die-cast motor housing as described in (1) to (6). [Industrial Applicability]

[0101] The present invention can be used to modify the surface of a die-cast motor housing. [Explanation of symbols]

[0102] 1 motor 2 rotors 2a Shaft insertion hole 21 Rotor core 22 Magnet 3 Stator 31 stator core 32 stator coil 4 shafts 5, 105 Motor housing 51 Main body 61 Parting Line 611 One side parting line 612 Other side parting line 62 Protrusion 62a Protruding tip surface 63, 163 Reforming section 63a, 163a radially outer 7 Die-cast products 71 Molded product protrusion 72, 73 Gate section 8. Die-casting equipment 81 Multiple molds 81a Mating surface 82 Cavity 83 Runner Gate 84 85 Overflow section 86 Overflow Gate L1 Depth of modified area L2 Height of parting line in the protruding direction T Rotate Tool T1 Rotating part T2 Friction Stir Pin W1 Modified material W2 Modified part

Claims

1. A motor housing made by die-casting, having a cylindrical main body portion, the main body portion having a parting line on an outer peripheral surface that protrudes outward and extends in the axial direction, The main body portion is At least a part of the outer circumferential surface in contact with the parting line has a modified portion in which the material structure is modified. Motor housing.

2. 2. The motor housing according to claim 1, The modified portion is The material structure is denser than the material structure constituting the main body portion. Motor housing.

3. The motor housing according to claim 2, The main body portion is a protrusion protruding outward from the main body on at least a portion of the outer circumferential surface that is in contact with the parting line, The modified portion is Located on the entire protruding tip surface of the protruding portion, Motor housing.

4. The motor housing according to any one of claims 1 to 3, The modified portion is The body portion has a depth toward the inside thereof, The depth of the modified portion in the protruding direction of the parting line is shorter than half the protruding height of the parting line; Motor housing.

5. The motor housing according to any one of claims 1 to 3, The modified portion is The body portion has a depth toward the inside thereof, The depth of the modified portion in the protruding direction of the parting line is Longer than half the protruding height of the parting line, Motor housing.

6. 2. The motor housing according to claim 1, The modified portion is The body is formed by friction stirring of the material constituting the body. Motor housing.

7. A method for manufacturing a die-cast motor housing having a cylindrical main body, comprising the steps of: a forming step of injecting molten metal from a gate into a cavity formed by a plurality of molds to form a die-cast molded product that will become the main body; a dividing step of dividing the die-cast molded product and a runner at the gate; a modification step of performing a modification treatment on a gate portion of the die-cast molded product, which is a boundary between the die-cast molded product and the runner formed by the dividing step, to modify the material structure; having Motor housing manufacturing method.

8. 8. The motor housing manufacturing method according to claim 7, The dividing step comprises: a step of dividing the die-cast molded product and an overflow portion, which is a discharge passage for molten metal, by an overflow gate; The modification step includes: a step of performing a modification treatment on a gate portion of the die-cast molded product, the gate portion being a boundary between the die-cast molded product formed by the dividing step and the overflow portion, to modify the material structure, Motor housing manufacturing method.

9. 9. The motor housing manufacturing method according to claim 7 or 8, In the modification step, The modification treatment is carried out by a friction stirring treatment in which a rotary tool is pressed against the gate portion. Motor housing manufacturing method.

10. 9. The motor housing manufacturing method according to claim 7 or 8, In the modification step, performing a modification treatment on the entire gate portion; Motor housing manufacturing method.

11. 9. The motor housing manufacturing method according to claim 7 or 8, In the modification step, The modification treatment is carried out by a friction stir treatment in which a friction stir pin of a rotary tool is pressed into the gate portion. Motor housing manufacturing method.

12. A rotating rotor; a stator positioned radially outward relative to the rotor; a motor housing in contact with the stator on the outer circumferential side of the stator; and The motor housing is a die-cast motor housing according to claim 1. Motor.

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