JP5731850B2 - Method of manufacturing yoke in rotating electric machine - Google Patents

Description

  The present invention relates to a technical field of a manufacturing method of a yoke in a rotating electric machine such as an electric motor which is a constituent member of a drive unit of an electric actuator provided in a vehicle such as a power window and a power seat.

  Generally, a yoke constituting a rotating electrical machine such as an electric motor, for example, a yoke such as an electric motor constituting an electric actuator, is required to be downsized while having high motor characteristics. Therefore, it is proposed to improve the motor characteristics while reducing the size by increasing the number of electric motors, and as such a yoke, it is formed in a polygonal cylindrical shape on the bottom side of the bottomed cylindrical shape, The oval cylindrical shape is formed by a polygonal cylindrical portion in which a magnet is fixed to a side piece, and a pair of flat plate portions and a pair of arc-shaped portions facing each other in the radial direction. A flat cylindrical portion that is formed and accommodates a brush holder unit, and a pair of side pieces facing the radial direction of the polygonal cylindrical portion and a pair of flat plate portions of the rectangular cylindrical portion are continuous in the axial direction. A yoke formed so as to be a shape portion has been proposed.

JP 2010-263689 A

The conventional yoke is formed by drawing a metal flat plate material using a punch and a die. In this forming process, a metal flat blank is formed into a bottomed cylindrical first formed body. The step of molding, the first molded body includes a polygonal cylindrical portion on the bottom side, a cylindrical portion on the opening side, and an inclined cylindrical portion that expands toward the opening side between the polygonal cylindrical portion and the cylindrical portion. A step of forming the second molded body, and an inclined cylindrical portion and a cylindrical portion following the pair of side pieces opposed in the radial direction of the polygonal cylindrical portion of the second molded body as a flat plate portion following the pair of side pieces. And a step of forming a third molded body having a flat portion that is long in the core direction. In this case, in the step of forming the third molded body, a punch having a molding surface along the cylinder inner surface of the third molded body is inserted into the cylinder of the second molded body, and the cylinder outer surface of the third molded body A die having a molding surface along the shape of the second molded body is fitted from the bottom side, and the inclined portion and the cylindrical portion of the second molded body are connected to the pair of side pieces of the polygonal cylindrical portion. The molding to be deformed is performed.
However, the molding surface formed on the opening side of the die is formed with a pair of flat plate portion molding surfaces and a pair of arcuate portion molding surfaces opposed to each other in the radial direction so as to mold the oval cylindrical portion. On the other hand, the second molded body has a shape in which an inclined cylindrical portion and a cylindrical portion are formed on the opening side of the polygonal cylindrical portion. For this reason, when forming the third molded body by fitting the molding surface of the die from the bottom side of the second molded body, when the die reaches the inclined cylindrical portion of the second molded body, the arc-shaped portion is formed. Although the surface does not deform the inclined cylindrical portion, the flat plate portion molding surface is started to be deformed so as to make the inclined cylindrical portion into a flat plate shape. The part facing the molding surface is deformed prior to the other part (the part facing the arcuate part molding surface).
By the way, in the case of drawing, in order to perform the molding operation smoothly, there is no gap between the molded body and the punch, but a predetermined clearance is provided between the die and the molded body. ing. For this reason, in the case of deforming only the specific part in the circumferential direction (flat part facing surface), as in the step of molding the third molded body, the part deformed by molding is not integral in the circumferential direction. A part that receives stress due to deformation and continues to the deformed part, in particular, in the conventional yoke, the side piece on the side of the polygonal cylinder part that follows the deformed part (the side piece constituting the flat part) is the die and the molded body. In this clearance, the punch is not transferred due to deformation, distortion, and spring back. In this case, there is a problem in that the flatness of the inner surface is lowered due to distortion and deformation generated in the side piece, and further, the spring back, and the integration of the magnet into the part is impaired. In addition, increasing the number of poles has the advantage that the thickness of the yoke can be reduced, but there is a problem that it becomes easy to vibrate and abnormal noise is generated, and there are problems to be solved by the present invention.

The present invention has been created in view of the above-mentioned circumstances and has been created for the purpose of solving these problems. The invention of claim 1 is directed to a yoke of a bottomed cylindrical rotating electrical machine in a polygonal cylindrical shape. A bottom-side polygonal cylinder part formed with a magnet fixed to each side piece, a cross-sectional area in the radial direction larger than that of the polygonal cylinder part, and a pair of flat plate parts and a pair of arcuate parts opposed to each other in the radial direction. And a pair of side pieces opposed to the radial direction of the polygonal cylinder part and a pair of flat plate parts of the oval cylinder part. A method of drawing using a die and a punch so as to form a flat portion continuous in the axial direction, the step of forming a metal flat plate into a bottomed cylindrical first formed body, Open the molded body between the polygonal cylinder part on the bottom side, the cylindrical part on the opening side, and the polygonal cylinder part and the cylindrical part. A step of forming into a second molded body having an inclined cylindrical portion that expands, and an inclined cylindrical portion and a cylindrical portion following a pair of side pieces facing in the radial direction of the polygonal cylindrical portion of the second molded body. The yoke is formed by forming a flat portion that is long in the axial direction as a flat plate portion following the pair of side pieces, and forming a third molded body having an oval cylindrical portion on the opening side of the polygonal cylindrical portion. In doing so, the flat portion of the yoke is formed using a die having a deformation preventing portion that prevents deformation of the inner surface of the flat portion on the forming surface facing the portion, and the deformation preventing portion is formed by forming the die. Axis that is provided in at least two locations in the circumferential direction of the surface and protrudes with a protrusion amount slightly larger than the clearance formed between the die and the flat portion, and extends from the side piece forming surface of the die to the flat plate portion forming surface. electric rotating machine, characterized by being configured by the direction elongate projecting piece It is a method of manufacturing a definitive York.
According to another aspect of the invention, the projecting piece is a yoke manufacturing method of the rotating electric machine according to claim 1, characterized in that the protruding tip is formed into a flat shape.

According to the first aspect of the present invention, the inner surface of the side piece constituting the flat portion of the yoke can be molded with a high level of accuracy, and the magnet can be securely fixed to the side piece, and the rotation can be performed with high reliability. Electricity can be provided. In addition , while being able to carry out smooth drawing, it is possible to improve the plane accuracy of the inner surface of the flat part including the side piece, and to improve the accuracy of the yoke inlay part, thereby improving the coaxial accuracy. Can be improved and the occurrence of abnormal noise can be reduced.
According to the invention of claim 2 , the natural frequency of the yoke can be adjusted by the shape of the tip end surface of the protrusion.

It is a whole perspective view of the electric motor with a reduction mechanism. 2A, 2B, 2C, and 2D are a left side view, a front sectional view, a right side view, and a perspective view, respectively, of the yoke of the motor unit. 3 (A) is a side view of a base material for forming a yoke, FIG. 3 (B) is a cross-sectional view of a first intermediate, FIG. 3 (C) is a cross-sectional view of a second intermediate, FIG. (E) is a plan view and a cross-sectional view of the third intermediate body, respectively, and FIGS. 3 (F) and (G) are a plan view and a cross-sectional view of the fourth intermediate body, respectively. 4A and 4B are a plan view and a sectional view of the fifth intermediate body, respectively, and FIGS. 4C and 4D are a plan view and a cross-sectional view of the sixth intermediate body, respectively. (F) is the top view and sectional drawing of a yoke, respectively. 5A and 5B are a bottom view of the die and a sectional view taken along line XX in FIG. 6A and 6B are a cross-sectional view and an enlarged view of a main part for explaining drawing processing by a die, respectively.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
In the drawings, 1 is an electric motor with a speed reducer, and the electric motor 1 with a speed reducer is used, for example, as a drive source of a power window device or a power seat device of a vehicle. The speed reduction mechanism unit 3 is provided.
The motor unit 2 includes a yoke 4 formed in a cylindrical shape with a bottom, and an armature and a brush holder (not shown) are housed therein. The worm gear formed in the extending portion is configured to be interlocked and connected to a worm wheel (not shown) housed in the casing 5. The casing 5 of the speed reduction mechanism unit 3 is provided with one end portion of a drive shaft 6 linked to the worm wheel so as to protrude outward, and the drive shaft 6 is linked to each device. The basic configuration is the same as that of the prior art, such that the driving force decelerated with the rotational drive of the motor unit 2 is output to each device.

  As will be described later, the yoke 4 constituting the motor unit 2 is formed by drawing based on a molding procedure in which the present invention is implemented, and has a bottomed cylindrical shape having a bottom portion 4a. Is formed. The bottom portion 4a is formed in a hexagonal shape, and a bearing portion 4b that rotatably supports the base end portion of the armature shaft is formed on the shaft core portion so as to protrude outward. And the bottom 4a side of the yoke 4 cylinder part is formed in the hexagonal cylinder part (equivalent to the polygonal cylinder part of this invention) 4c formed in the hexagonal cylinder shape, Each side piece 4d of this hexagonal cylinder part 4c The N pole and the S pole of the permanent magnet 7 for forming a magnetic field are alternately fixed to form a hexapole motor unit 2. Further, on the opening side of the yoke 4 cylinder portion, a pair of flat plate portions 4e and a pair of arcuate portions 4f opposed to each other in the radial direction form an oval cylindrical tube portion 4g. The oval cylindrical portion 4g has a radial cross-sectional area larger than that of the hexagonal cylindrical portion 4c, and is configured to accommodate the brush holder unit therein.

Further, in the yoke 4, a pair of side pieces 4d opposed to each other in the radial direction of the hexagonal cylindrical portion 4c on the bottom 4a side and a pair of flat plate portions 4e of the oval cylindrical portion 4g are continuous in a flush manner. The flat portion F that is long in the axial direction is constituted by the piece 4d and the flat plate portion 4e, whereby the yoke 4 is reduced in size. On the other hand, between the side piece 4d of the hexagonal cylinder part 4c and the arcuate part 4d of the oval cylinder part 4e other than that constituting the flat part F, a step that widens from the side piece 4d in the outer diameter direction. A portion 4h is formed.
Further, a flange portion 4i extending in the outer diameter direction is formed at the opening end of the oval cylindrical portion 4g of the yoke, and the flange portion 4i is formed on the flange portion 5a formed on the casing 5 of the speed reduction mechanism portion 3. It is configured to be abutted and screwed to the flange portion 5a via a plurality of through holes 4j opened in the flange portion 4i.

Next, a procedure for forming the yoke 4 will be described with reference to FIGS.
In the first step, as shown in FIG. 3 (A), the base material 10 cut into a circular shape having a predetermined diameter is drawn by a flat metal plate material, and shown in FIG. 3 (B). Thus, the bottomed cylindrical first intermediate body (corresponding to the first molded body of the present invention) 11 composed of the spherical bottom equivalent portion 11a and the cylindrical portion 11b is molded (in the first step of the present invention). Equivalent to).

  In the second step, the first intermediate body 11 is drawn to form a second intermediate body 12 shown in FIG. The second intermediate body 12 is formed with a spherical bottom equivalent part 12a and a cylindrical part 12b having a smaller diameter than the bottom equivalent part 11a and the cylindrical part 11b of the first intermediate 1, and an opening of the cylindrical part 12b. A flange-corresponding portion 12c for forming the flange portion 4i of the yoke 4 is formed so as to expand in an inclined manner from the side end portion toward the outer diameter side.

  In the third step, the second intermediate body 12 is drawn to form a third intermediate body 13 (corresponding to the second molded body of the present invention) 13 shown in FIGS. 3D and 3E (the present invention). 2). The third intermediate body 13 is smaller in diameter than the second intermediate body 12 and has a hexagonal bottom equivalent part 13a, and a hexagonal hexagonal cylinder smaller in diameter than the cylindrical part 12b on the bottom equivalent part 13a side. A corresponding portion 13b is formed. An inclined cylindrical portion 13c that expands toward the opening side of the hexagonal cylinder equivalent portion 13b, and a cylindrical portion 13d that is smaller in diameter than the cylindrical portion 12b of the second intermediate body 12 are formed. Further, the cylindrical portion 13d A flange-corresponding portion 13e that expands in a curved shape toward the outer diameter side is formed on the opening end side.

In the fourth step, the third intermediate body 13 is drawn to form a fourth intermediate body 14 (corresponding to the third molded body of the present invention) shown in FIGS. 3 (F) and 3 (G) (the present invention). Corresponding to the third step). The fourth intermediate body 14 includes an inclined cylindrical portion 13d and a cylindrical portion 13c that follow a pair of side piece equivalent portions 13f that face each other in the radial direction of the hexagonal cylinder equivalent portion 13b, and a pair of side piece equivalent portions 13f. The flat flat surface is drawn so as to form an oval shape on the opening side, and has a hexagonal bottom equivalent portion 14a and a hexagonal cylinder of the yoke 4 positioned on the bottom equivalent portion 14a side. Hexagonal cylinder equivalent part 14b having the same shape as the part 4c, a pair of flat plate equivalent parts 14d and a pair of arcuate shapes that are radially opposed to a pair of side piece equivalent parts 14c that are opposite to each other in the radial direction The equivalent portion 14e is located between the oval cylindrical equivalent portion 14f having the same shape as the oval cylindrical portion 4g of the yoke 4, the hexagonal cylinder equivalent portion 14b, and the arc equivalent portion 14e. A step equivalent portion 14g having the same shape as the step portion 4h; A flange corresponding portion 14h for expanding a curved shape toward the outer diameter side from the open end of the oval shape cylinder corresponding portion 14f is formed. As described above, the fourth intermediate body 14 is formed so that a portion from the hexagonal cylinder equivalent part 14b to the oval cylinder equivalent part 14e has the same shape as the yoke 4, and corresponds to a pair of side pieces of the hexagonal cylinder equivalent part 14b. The flat plate-like portion 14d of the flat portion 14c and the flat plate-like portion 14d of the oval-shaped tube equivalent portion 14f are formed into a flat flat surface that is the same shape as the flat portion F of the yoke 4. .
In the fourth step, the present invention is implemented, and the fourth intermediate body 14 is formed by drawing using a die 15 which will be described later, so that the outer surface of the pair of flat portion corresponding portions 14F is formed in the axial direction. While two long circumferential deformation prevention marks 4k are respectively formed, a pair of side piece equivalent parts 14c of the hexagonal cylinder equivalent part 14b constituting the flat part equivalent part 14F, that is, a pair of side pieces of the yoke 4 4d and the inner surface of the flat plate portion 4e following the outer piece 4d are configured so as to be formed into a surface with high planar accuracy that does not cause deformation, distortion, or springback.

  That is, as shown in FIGS. 5A and 5B, the die 15 used in the fourth step is configured to have a surface that forms the outer surface of the portion excluding the bottom equivalent portion 14a of the fourth intermediate body 14. The hexagonal cylindrical portion molding surface 15a is formed in a penetrating manner. Further, on the distal end side (the lower end side in FIG. 5 (A)) of the hexagonal cylinder part molding surface 15a, the radial direction follows the pair of side piece molding surfaces 15b facing the radial direction in the hexagonal cylinder part molding surface 15a. Between the opposed flat plate portion forming surface 15c and the pair of arcuate portion forming surfaces 15d, the oval cylindrical portion forming surface 15e on the opening side, the hexagonal tube portion forming surface 15a and the arcuate portion forming surface 15d. A flange-corresponding portion forming surface 15g is formed to expand in a curved shape from the opening end of the stepped portion forming surface 15f and the oval cylindrical portion forming surface 15e toward the outer diameter side. And each molding surface 15a, 15b, 15c, 15d, 15e, 15f, 15g of the die 15 and the outer surface of the fourth intermediate body 14 facing these molding surfaces 15a, 15b, 15c, 15d, 15e, 15f, 15g Are set so that a slight clearance H is provided (see FIG. 6B).

Further, the flat part F of the yoke 4, particularly the side piece 4 d constituting the flat part F, is provided at a part from the pair of side piece molding surfaces 15 b of the die 15 to the bottom side part of the pair of flat plate part molding surfaces 15 c. A deformation preventing portion is provided for preventing deformation of the inner surface. The deformation preventing portion according to the present embodiment has a pair of side protrusions 15h that are long in the axial direction so as to extend from the side piece forming surface 15b to the bottom side portion of the flat plate forming surface 15c and project toward the axial side. Two pieces (two and one pair) are provided with a predetermined gap in the circumferential direction with respect to each of the bottom side portions of the piece forming surface 15b and the flat plate portion forming surface 15c.
Each of the projecting pieces 15h is formed on a flat projecting tip surface 15i having a projecting tip having a predetermined width in the circumferential direction, and the projecting amount H1 of each projecting piece 15h is equal to the side piece or the flat plate portion. The dimension is set to be slightly longer (H1> H) than the clearance H provided between the molding surfaces 15b and 15c and the fourth intermediate body 14 to be molded. Accordingly, the projecting pieces 15h forming portions of the molding surfaces 15b and 15c of the side pieces and the flat plate portions are configured such that the clearance H between the fourth intermediate body 14 is eliminated.
In the fourth step, a punch (not shown) used corresponding to the die 15 is formed with a dimension setting that does not provide a clearance with the inner surface of the fourth intermediate body 14.

  In the fourth step, the third intermediate body 13 is externally fitted to a punch formed along the inner surface of the fourth intermediate body 14, and the bottom equivalent portion is formed with respect to the third intermediate body 13 in which the punch is internally fitted. Drawing is performed by externally fitting the die 15 from the side 13a and displacing the end surface 15j on the opening end side of the die 15 in the axial direction until it abuts against a frame (not shown) on which a punch is provided. In this case, the die 15 is externally fitted to the third intermediate body 13 to start drawing, and the side piece equivalent portion of the hexagonal cylinder equivalent portion 13b of the third intermediate body 13 shown by the one-dot chain line in FIG. When the tip of the projecting piece 15h formed on the side surface of the die 15 and the molding surfaces 15b and 15c of the flat plate portion reaches the front end in the axial direction (external fitting direction), the projecting tip surface 15i of the projecting piece 15h is on the side. It is comprised so that it may contact | abut to the piece equivalent part 13f. When the die 15 is pushed down from this state, the protruding pieces 15h of the die 15 (two protruding pieces 15h) sandwich the side piece corresponding portions 13f together with the punches fitted into the side piece corresponding portions 13f. In this state, drawing is performed, and each side piece corresponding portion 13f is formed in a state where the transfer of the punch is good.

  Then, the opening side edge of the flat plate portion molding surface 15c of the die 15 reaches the inclined cylindrical portion 13d of the third intermediate body 13 shown by the two-dot chain line in FIG. When pushed down, the flat plate portion forming surface 15c deforms the inclined cylindrical portion 13c and the cylindrical portion 13d in two circumferential directions as much as possible to form the flat portion F of the yoke 4, thereby forming the flat plate corresponding portion 14c. In the process of forming the flat plate equivalent portion 14c, the stress generated by the deformation of the two portions in the circumferential direction of the inclined cylindrical portion 13c and the cylindrical portion 13d corresponds to a pair of side pieces of the hexagonal cylinder equivalent portion 13b following the deformation portion. Although acting on the part 13f, the two protruding pieces 15h formed on the side piece molding surface 15b of the die 15 are opposed to the pair of side piece equivalent parts 13f as described above. Therefore, with the deformation of the inclined cylindrical portion 13c and the cylindrical portion 13d, the side piece equivalent portion 13f is deformed toward the clearance H between the side piece equivalent portion 13f and the side piece molding surface 15b. By pressing the side piece equivalent portion 13f opposed to each pair of projecting pieces 15h against the inner surface side punch, the distortion and deformation of the side piece equivalent portion 13f are restricted, whereby each side piece equivalent portion 13f Further, deformation and distortion, and further, spring back does not occur, and the plane accuracy is not impaired.

In the fourth step of drawing, the projecting piece 15h squeezes the side piece corresponding portion 13b of the third intermediate body 13, whereby the flat portion corresponding portion 14F of the fourth intermediate body 14 (flat portion F of the yoke 4). As described above, the long deformation-preventing marks 4k are formed in the circumferential direction in the two axial directions as the marks rubbed against the protrusions 15h. The deformation prevention mark 4k is formed in a shallow groove shape depending on the protruding amount of the projecting piece 15h. However, as in the present embodiment, the protruding amount H1 of the projecting piece 15h is changed to the die 15 and the fourth intermediate body. In the case where the clearance H is set slightly longer than the clearance H that is formed between the outer peripheral surface 14 and the outer surface 14 of the flat portion 14F, the outer surface of the flat portion corresponding portion 14F is rubbed.
Incidentally, when the protruding amount of the protruding piece is made larger than the protruding amount H1, the deformation prevention trace is formed in a shallow groove shape, but the protruding amount of the protruding piece is increased, and further, the number of protruding pieces is reduced. Increasing the width of the projecting piece in the circumferential direction increases the knockout force in drawing in any case, and the projecting piece is necessary to prevent distortion and deformation of the inner surface of the side piece. It is set to the number, protrusion amount, and protrusion width.
Furthermore, the length of the projecting piece is not limited to the one that is long in the axial direction from the bottom side portion of the flat plate molding surface 15c to the entire side piece molding surface 15b, as in the present embodiment. It may be a short one from the bottom side portion of the flat plate forming surface 15c to the intermediate portion of the side piece forming surface 15b. Even in this case, deformation and distortion of the side piece can be prevented, and the flat portion equivalent portion Deformation prevention marks are formed long.

In a fifth step following the fourth step, the fourth intermediate 14 is drawn to form a fifth intermediate 16 shown in FIGS. 4 (A) and 4 (B). The fifth intermediate body 16 is formed with a protruding portion (bearing equivalent portion) projecting outwardly at the shaft core portion of the bottom equivalent portion 14a of the fourth intermediate body 14, and the flange equivalent portion 14h is formed as an oval-shaped cylinder equivalent portion. 14 f is drawn so as to be perpendicular to the hexagonal bottom equivalent portion 16 a, the bottom equivalent portion 16 a, the shaft equivalent portion 16 b, and the bottom equivalent portion 16 a. A side hexagonal cylinder equivalent part 16c, a pair of side plate equivalent parts 16d facing the radial direction of the hexagonal cylinder equivalent part 16c, a pair of flat plate equivalent parts 16e and a pair of arcuate equivalent parts 16f that are opposed to each other in the radial direction. The provided oval shaped cylinder equivalent portion 16g on the opening side, the step equivalent portion 16h between the hexagonal cylinder equivalent portion 16c and the arcuate equivalent portion 16f, and the opening end of the oval shaped cylinder equivalent portion 16g toward the outer diameter side. Flange equivalent part 16i that is bent and extends perpendicularly There is formed.
The portion from the hexagonal cylinder equivalent part 16c to the oval cylinder equivalent part 16g of the fifth intermediate body 16 is formed in the same shape as the yoke 4.

In the subsequent sixth step, the fifth intermediate 16 is drawn to form a sixth intermediate 17 shown in FIGS. 4 (C) and 4 (D). The sixth intermediate body 17 is narrowed so that the angular accuracy of the R-shaped portion at the projecting end of the bearing equivalent portion 16b of the fifth intermediate body 16 is formed into an acute angle so as to have the same shape as the bearing portion 4b of the yoke 4. A hexagonal bottom equivalent part 17a, a bottom equivalent part 17a shaft equivalent part 17b, a hexagonal cylinder equivalent part 17c on the bottom equivalent part 17a side, Equivalent to a small oval cylinder on the opening side provided with a pair of flat plate corresponding portions 17e and a pair of arcuate corresponding portions 17f facing in the radial direction following the pair of side piece corresponding portions 17d facing in the radial direction of the hexagonal tube corresponding portion 17c. A portion 17g, a step equivalent portion 17h between the hexagonal cylinder equivalent portion 17c and the arc-like equivalent portion 17f, and a bent portion extending from the opening end of the oval cylinder equivalent portion 17g toward the outer diameter side. The flange equivalent part 17i to be formed is formed.
The sixth intermediate body 17 is formed in the same shape as the yoke 4 as a finished product, except for the flange-corresponding portion 17i.

In the seventh step, which is the final step, the flange equivalent portion 17i of the sixth intermediate body 17 is punched out and pressed so as to have the shape of the flange portion 4i in which the through hole 4j of the yoke 4 that is the finished product is opened. As a result, a finished product of the yoke 4 shown in FIGS. 4E and 4F is formed.
In the yoke 4 formed in this way, the flat portion F is formed as the flat portion equivalent portion 14F in the fourth step, but it protrudes from the side surfaces of the die 15 and the respective molding surfaces 15c and 15d of the flat plate portion. When the piece 15h is formed and the two portions in the circumferential direction of the inclined cylindrical portion 13d and the cylindrical portion 13c of the third intermediate body 13 are deformed to form the flat portion equivalent portion 14F, two protruding pieces 15h is in contact with each side piece equivalent portion 13f of the hexagonal cylinder equivalent portion 13b following the front deformation portion, and the side piece equivalent portion 13f is squeezed together with the punches inside the protrusion piece 15h and the side piece equivalent portion 13f. Thus, deformation of the side pieces 4d and the flat plate portion 4e of the hexagonal cylinder portion 4c constituting the flat portion F is prevented. As a result, the planar accuracy of the inner surfaces of the side piece 4d and the flat plate portion 4e is increased, so that the magnet 7 can be securely fixed to the side piece 4d, and the accuracy of the inlay portion is also improved, improving the coaxial accuracy. Generation of abnormal noise can be reduced, and a highly reliable motor unit 2 (electric motor 1 with a speed reduction mechanism) can be provided. Then, on each of the side pieces 4d and the flat plate portion 4e constituting the flat portion F of the yaw 4, two deformation prevention marks 4k are formed by squeezing with the protruding tip surface 15i of the protruding piece 15h and the punch, respectively. .

  In the present embodiment configured as described, the bottomed cylindrical yoke 4 of the electric motor 1 with the speed reduction mechanism 1 (motor unit 2) is formed in a hexagonal cylindrical shape, and the bottom portion where the magnet 7 is fixed to each side piece 4d. 4a side hexagonal cylinder part 4b and a hexagonal cylinder part 4b having a larger cross-sectional area in the radial direction, a pair of flat plate parts 4e and a pair of arcuate parts 4f opposed to each other in the radial direction, A pair of side pieces 4d facing the radial direction of the hexagonal cylinder part 4b and a pair of flat plate parts 4e of the oval cylinder part 4g are provided in the axial direction. It becomes the flat part F which continues to. In the case of drawing the yoke 4 using a die 15 and a punch, a step of forming a base 10 made of a metal flat plate into a bottomed cylindrical first intermediate body 11 (first molded body); Inclined cylindrical portion 13c that expands the first intermediate body 11 toward the opening side between hexagonal cylinder equivalent portion 13b on the bottom equivalent portion 13a side, cylindrical portion 13d on the opening side, hexagonal cylinder equivalent portion 13b, and cylindrical portion 13d. And an inclined cylinder following the pair of side piece equivalent portions 13f facing the radial direction of the hexagonal cylinder equivalent portion 13b of the third intermediate body 13 and the third intermediate body 13 (second molded body). The flat portion equivalent portion 14F long in the axial direction is formed by using the portion 13c and the cylindrical portion 13d as a flat plate equivalent portion 14d following the pair of side piece equivalent portions 13f, and an oval cylinder is formed on the opening side of the hexagonal cylinder equivalent portion 14b. The fourth intermediate body 14 (third molded body) having the corresponding portion 14f is formed. It will be formed by the steps of. Then, in forming the flat portion corresponding portion 14F of the fourth intermediate body 14 that becomes the flat portion F of the yoke 4, a die for forming the flat portion corresponding portion 14F (the flat plate portion F of the yoke 4). Since the side piece molding surface 15b and the flat plate portion molding surface 15c are provided with a deformation preventing portion for preventing the deformation of the inner surface of the flat portion corresponding portion 14F, the flat portion of the hexagonal cylindrical portion 4c of the yoke 4 is provided. The inner surface of the side piece 4d constituting F can be prevented from being distorted and deformed, and spring back can be prevented, and the plane accuracy can be improved, and the magnet 7 can be securely fixed to these side pieces 4d. A highly reliable electric motor 1 (motor unit 2) with a speed reduction mechanism can be provided.

  As described above, in the embodiment in which the present invention is implemented, in the side piece 4d constituting the flat portion F of the yoke 4, the planar accuracy of the inner surface is improved. The deformation preventing portions provided on the side piece forming surface 15b and the flat plate portion forming surface 15c of the die 15 are provided at two locations in the circumferential direction of the respective forming surfaces 15b and 15c of the die 15, and the die 15 and the flat portion corresponding portion. It is comprised by the protrusion 15h long in the axial direction which protrudes by the protrusion amount H1 slightly larger than the clearance H formed between 14F. As a result, it is possible to reduce the disadvantages (increased knockout force, excessive wear, etc.) due to the contact between the projecting piece 15h and the flat portion corresponding portion 14F during drawing, and smooth drawing is performed. In addition to being able to improve the plane accuracy of the inner surface of the side piece 4d and the flat plate portion 4e, the magnet 7 can be securely fixed to the side piece 4d, and the flat plate portion 4e is included. The accuracy of the inlay portion is also improved, the coaxial accuracy is improved, the occurrence of abnormal noise can be reduced, and the motor portion 2 can be made more reliable.

  Further, in this device, the protruding tip surface 15i of the projecting piece 15h is formed in a flat shape, and the outer surface of the flat portion F of the yoke 4 has a predetermined circumferential direction width as a deformation prevention mark 4k. A long scuff is formed in the core direction. The protrusions 15h formed on the die 15 are adjusted in number, shape (width, length, protrusion length), and formation position, thereby forming the shape and formation of the deformation prevention marks 4k formed on the yoke 4. It has been verified that the position changes, thereby changing the natural frequency of the yoke 4. For this reason, when the electric motor 1 with a speed reduction mechanism has natural vibration, the number of deformation prevention marks 4k, the circumferential direction width, the axial direction length, the groove depth (scratch depth), and the position are appropriately changed. Thus, there is an advantage that the natural frequency of the yoke 4 can be adjusted so that the yoke 4 does not resonate with the natural vibration of the electric motor 1 with the speed reduction mechanism.

  Of course, the present invention is not limited to the above-described embodiment, and in order to form the inner surface shape of the side piece of the flat portion with high planar accuracy, drawing using a die provided with a deformation prevention portion. This step may be carried out in the fourth step of forming the flat portion as in the first embodiment, but after forming the flat portion, the step of forming the bearing portion on the bottom of the yoke Any process may be performed as long as it is a drawing process using a die on which a molding surface facing the flat part is formed, such as a process of molding the flange part of the yoke. In the case described above, for example, two protrusions are provided in the circumferential direction with a predetermined gap as a deformation prevention portion on the molding surface for molding the flat portion with respect to the side piece of the flat portion in which distortion or deformation has occurred. By drawing using a die, the deformation of the side piece of the polygonal cylinder part constituting the flat part can be corrected, and thereby the planar accuracy of the inner surface of the side piece can be improved.

  The present invention can be used for a yoke in which the brush holder housing portion and the magnet fixing portion are formed in different shapes.

DESCRIPTION OF SYMBOLS 1 Electric motor with reduction gear 2 Motor part 4 Yoke 4c Hexagonal cylinder part 4d Side piece 4e Flat plate part 4g Oval cylinder part 7 Permanent magnet 11 First intermediate body 12 Second intermediate body 13 Third intermediate body 14 Fourth intermediate body 14c Side piece equivalent portion 14F Flat portion equivalent portion 15 Die 15c Side piece molding surface 15d Flat plate portion molding surface 15i Projection piece 15j Tip surface 16 Fifth intermediate body 17 Sixth intermediate body

Claims (2)

The yoke of the bottomed cylindrical rotating electric machine is formed in a polygonal cylindrical shape, the polygonal cylindrical portion on the bottom side where the magnet is fixed to each side piece, and the radial cross-sectional area is larger than the polygonal cylindrical portion, in the radial direction A pair of opposed flat plate portions and a pair of arcuate portions that are formed into an oval cylindrical shape and have an oval cylindrical portion on the opening side in which the brush holder unit is accommodated, and are opposed to the radial direction of the polygonal cylindrical portion The side plate and the pair of flat plate portions of the oval cylindrical portion are drawn using a die and a punch so that the flat plate portion is continuous in the axial direction. A step of forming the first molded body into a cylindrical shape, and an inclination in which the first molded body is expanded toward the opening side between the polygonal cylindrical portion on the bottom side, the cylindrical portion on the opening side, and the polygonal cylindrical portion and the cylindrical portion. A step of forming a second molded body having a cylindrical portion, and a pair of side pieces facing in the radial direction of the polygonal cylindrical portion of the second molded body A third molded body having a flat cylindrical portion that is long in the axial direction as a flat plate portion following the pair of side pieces, and the oblong shaped cylindrical portion on the opening side of the polygonal cylindrical portion. In forming the yoke by the forming step, the yoke flat portion is formed using a die provided with a deformation preventing portion that prevents deformation of the flat portion inner surface on the forming surface facing the portion , The deformation preventing portions are provided in at least two locations in the circumferential direction of the die forming surface, and protrude with a protruding amount slightly larger than the clearance formed between the die and the flat portion, and the die side piece forming surface A method of manufacturing a yoke in a rotating electrical machine, characterized in that it is constituted by a long protrusion in the axial direction extending from the flat surface to the flat plate portion forming surface . Protrusion is yoke manufacturing method of the rotating electric machine according to claim 1, characterized in that the protruding tip is formed into a flat shape.

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