JP2007312495A - Assembled commutator and manufacturing method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an assembled commutator and a manufacturing method therefor wherein multiple commutator pieces can be firmly disposed and fixed on the outer circumferential surface of an insulating substrate. <P>SOLUTION: Multiple commutator pieces 21 having a riser portion 22 are disposed and fixed on the outer circumferential surface of the insulating substrate 10 formed in a cylindrical shape with a slit 23 provided between the individual commutator pieces 21. Washers 30 are fit onto the periphery of the commutator pieces 21 to press and fix them against the outer circumferential surface of the insulating substrate 10. In a flange portion 12 provided at the base end of the insulating substrate 10, there are formed grooves 15 for fitting the base parts of the riser portions 22. A protrusion 14a protruded toward the riser portion 22 is formed on the opening side of each groove 15, and the protrusions 14a are swelled toward the grooves 15 by plastic deformation to fix the base parts of the riser portions 22 in the grooves 15. When fit, the washers 30 cover the swelled portions 15a and press the commutator pieces 21 against the insulating substrate 10. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an assembly type commutator attached to a rotary electric machine such as a small motor and a method for manufacturing the same.

  Small motors are widely used in various fields such as audio / video equipment and optical precision equipment, and in recent years, light weight, thinning, and high performance are progressing. In the small motor, a permanent magnet is mounted inside a casing, and a rotor that is rotatably supported by a bearing is disposed to face the permanent magnet. The rotor is provided with a commutator unit having a commutator piece, and a brush installed in the casing is in sliding contact with the commutator unit to supply power to the rotor armature winding.

  There are two types of commutator units: a mold type that integrates the whole with a thermosetting resin and an assembly type that uses a thermoplastic resin for the insulating part, but it has relatively little current and heat generation. Assembling type commutator units are often used for small motors.

  The assembly type commutator unit is generally known to have a configuration disclosed in, for example, Japanese Patent Application Laid-Open No. 2000-92793 (Patent Document 1). 9 is an exploded perspective view showing a conventional assembly type commutator unit, and FIG. 10 is a cross-sectional view showing a cross section thereof. The commutator unit includes an insulating base 1 in which a flange portion 3 is formed at one end of a cylindrical portion 2, three commutator pieces 4 made of a conductive metal attached to the insulating base 1, and a commutator piece 4. A washer 5 is provided which is fitted on the outer periphery and presses and fixes the commutator piece 4 to the outer peripheral surface of the insulating substrate 1. The commutator piece 4 is curved in an arc shape, and has a commutator portion 4a that is in sliding contact with a brush of a small motor (not shown), and a riser portion 4b that is radially connected from one end side of the commutator portion 4a. Yes. An end portion of an armature winding (not shown) is connected to the riser portion 4b.

  The washer 5 is usually made of a material having an electrical insulating function made of a fibrous material such as paper. The washer 5 is fitted with the three commutator pieces 4 on the outer peripheral surface of the insulating base 1 and then inserted from the upper end side in the figure to press the commutator pieces 4 against the outer peripheral surface of the insulating base 1. It is fixed in the state. However, when the dimensions of the washer 5 are changed, the pressing force of each commutator piece 4 is changed, and there arises a problem that the commutator piece 4 comes out of the insulating base body 1 due to vibration or impact. was there.

  In order to avoid the problem of the fixing means by the washer as described above, a means for increasing the fixing strength of the commutator piece to the insulating base without using a washer is disclosed in Japanese Patent Application Laid-Open No. 8-149760 (Patent Publication 2). Is disclosed. In other words, the assembly type commutator is formed with a plurality of outwardly recessed grooves on the side surface of the flange portion formed in the cylindrical portion, and the recessed grooves are formed outwardly from the three conductive commutator pieces. The terminal part for armature winding connection bent toward is stored. And the convex part is provided in the side wall and terminal part of a ditch | groove, and when a terminal part is press-fitted in a ditch | groove, it is comprised so that a terminal part may be latched in the state which the convex part and the side wall deform | transformed. .

JP 2000-92793 A JP-A-8-149760

  According to the assembly-type commutator disclosed in Patent Document 2, the terminal portion of the commutator piece is press-fitted into the recessed groove formed in the flange portion, so that the above-described washer can be omitted. . However, due to variations in dimensional accuracy between the groove formed on the side surface of the flange portion and the terminal portion of the commutator piece, there are those with low press-fitting strength, which may be caused by vibration or dropping that occurs when a small motor rotates. There may be a serious problem that the commutator piece is pulled out by impact. In particular, in the case of an ultra-small commutator with an outer diameter of 3 mm or less attached to the outer periphery of the cylindrical part, the required press-fit strength is small because the dimensions of the concave groove and the terminal part of the commutator piece are small. As a result, there has been a problem that variation in press-fit strength due to dimensional variation becomes large, and as a result, it cannot be used for an ultra-small assembly type commutator.

  Accordingly, an object of the present invention is to provide an assembly type commutator capable of firmly arranging and fixing a plurality of commutator pieces on the outer peripheral surface of an insulating base with a simple configuration, and a method for manufacturing the commutator. .

  In order to solve the above-mentioned problem, a manufacturing method of an assembly type commutator according to the invention of claim 1 includes a plurality of commutators having a commutator portion formed in an arc shape and a riser portion connected to the commutator portion. An assembling type commutator in which a piece is provided with a slit on an outer peripheral surface of a cylindrical insulating base, and a washer is fitted on the outer periphery of the commutator piece to press and fix the outer peripheral surface of the insulating base. The insulating base is formed of a synthetic resin having thermoplasticity, and a flange portion provided on the base end side is formed with a groove portion for fitting the base portion of the riser portion, and the opening side of the groove portion is in the direction of the riser portion. The protrusion part protruded in this is formed. This protrusion is plastically deformed by a heating means and bulges in the direction of the groove, thereby fixing the base of the riser part in the groove. Then, the gist is that the bulging portion is covered by fitting the washer into the outer periphery of the commutator piece and the commutator piece is pressed against the insulating base.

  According to a second aspect of the present invention, in the commutator piece, the washer is formed in a ring shape, an outer diameter is formed to cover the bulging portion, and an inner diameter is disposed on the outer peripheral surface of the insulating base. The gist is that it is formed in a size to press.

  Further, according to the third aspect of the present invention, a plurality of commutator pieces having a commutator portion formed in an arc shape and a riser portion connected to the commutator portion are provided on the outer peripheral surface of the insulating base formed in a cylindrical shape. On the other hand, it is a method of manufacturing an assembling type commutator in which a slit is provided between each commutator piece and then a washer is fitted to the outer periphery of the commutator piece and pressed and fixed to the outer peripheral surface of the insulating base. The base portion of the riser portion is fitted into the groove portion of the flange portion provided on the base end side of the insulating base formed of a synthetic resin having thermoplasticity, and the protrusion portion formed to protrude to the opening side of the groove portion is provided. The riser part is fixed in the groove part by bulging in the groove part direction by plastic deformation, and the washer is fitted to the outer periphery of the commutator piece to insulate the commutator piece. While pressing and fixing to the base, the bulge The gist is that it is coated.

  Furthermore, in the invention described in claim 4, the protrusion is bulged by being plastically deformed in the direction of the riser by a pressing tool heated by a heating means, and the base of the riser is inserted into the groove by the bulge. The gist is that the washer is fitted into the outer periphery of the commutator piece and covers the bulging portion.

  According to the assembly type commutator according to the present invention, the riser portion of the plurality of commutator pieces arranged and fixed on the outer peripheral surface of the cylindrical insulating base is formed in the groove formed in the flange portion of the insulating base. Since the riser portion is pressed by plastically deforming and projecting the protrusion formed on the opening side of the groove portion, each commutator piece can be firmly fixed to the outer peripheral surface of the insulating base. it can. Further, since the washer presses and fixes each commutator piece to the outer peripheral surface of the insulating base, it is possible to prevent the commutator pieces from separating in the radial direction due to centrifugal force during rotation. Moreover, since the protrusions formed on the insulating base are fixed by plastic deformation, the commutator pieces can be securely fixed even if the riser portion of the commutator pieces and the groove portions of the insulating base are uneven. It becomes. In addition, since the washer covers the bulging portion, even if a thread-like whisker occurs due to the stringing phenomenon (misting) after the protrusion is heated and plastically deformed, the whisker is pressed by the washer, and the commutator piece It is possible to prevent protrusions and splashes.

  According to the invention described in claim 2, the outer diameter of the washer formed in a ring shape is formed so as to cover the bulging portion, and the inner diameter is pressed on the outer peripheral surface of the insulating base. Since the washer is lightly press-fitted into the commutator piece even if thread-like whiskers occur on the commutator piece side, the whiskers are returned to the insulating substrate side. Can be prevented from protruding and scattering.

  According to the manufacturing method of the assembly-type commutator according to the present invention, after the riser portions of the plurality of commutator pieces are fitted into the groove portions formed in the flange portion of the insulating base, the protrusions are rectified by plastic deformation. The child piece can be easily fixed. Furthermore, by inserting the washer into the outer peripheral surface of each commutator piece, it is possible to fix each commutator piece to the outer peripheral surface of the insulating base and to prevent protrusion and scattering due to the pressing of the thread-like whiskers.

  According to the invention described in claim 4, the base portion of the riser portion can be fixed in the groove portion by a simple method in which the protruding portion is plastically deformed and bulged by the pressing tool heated by the heating means. Moreover, since the washer is fitted to the outer periphery of the commutator piece and covers the bulging portion, it is possible to simultaneously prevent the commutator piece from detaching in the outer peripheral direction and preventing protrusion and scattering by pressing the filamentous whisker. it can.

  The assembly type commutator is configured such that a plurality of commutator pieces each having a commutator portion formed in an arc shape and a riser portion connected to the commutator portion are rectified with respect to the outer peripheral surface of the insulating base formed in a cylindrical shape. A slit is provided between the element pieces and fixed. Further, a washer is fitted on the outer periphery of the commutator piece and is fixed to the outer peripheral surface of the insulating base. In this assembly type commutator, a groove portion that fits the base portion of the riser portion is formed in the flange portion provided on the base end side of the insulating base, and the groove portion projects toward the riser portion on the opening side. The part is formed to protrude. The protruding portion can be plastically deformed, and the protruding portion is plastically deformed to bulge in the direction of the groove portion, and the base portion of the riser portion is fixed in the groove portion by the bulging portion. Further, the washer is fitted on the outer periphery of the commutator piece. Then, the washer is fitted on the outer periphery of the commutator piece to cover the bulging portion and press the commutator piece against the insulating base.

  1 is a plan view of an assembly type commutator according to an embodiment of the present invention, FIG. 2 is a sectional view of the commutator, FIG. 3 is an exploded perspective view, and FIGS. 4A and 4B are riser portions of commutator pieces. It is explanatory drawing which shows the process of fixing. As shown in FIGS. 1 to 3, the assembly type commutator includes an insulating base 10 formed of an electrically insulating material made of a resin having plasticity such as a thermoplastic resin formed in a cylindrical shape, and a conductive metal. The commutator portion 20 is composed of a plurality of commutator pieces 21 attached to the outer periphery of the insulating base 10 and the commutator piece 21 is disposed on the outer periphery of the commutator piece 21 and presses the commutator piece 21 against the outer peripheral surface of the insulating base 1. And a washer 30 to be fixed.

  As will be described later, the insulating base 10 is made of an engineering plastic that is plastically deformed by heating and has a small coefficient of thermal expansion and change with time, such as a synthetic resin such as polyamide 9T resin and polybutylene terephthalate (PBT). The insulating substrate 10 is formed by a molding means such as injection molding using a predetermined mold using these resins.

  The insulating base 10 is integrally formed with a cylindrical portion 11 and a flange portion 12 having a diameter larger than that of the cylindrical portion 11 on the base end side, and a rotation shaft such as a motor (not shown) is provided in the central through hole 13. Inserted. An annular jetty portion 14 is formed on the end surface of the flange portion 12, and a groove portion 15 for fitting the riser portion 22 of the commutator piece 21 is equidistantly spaced about every 120 degrees in the circumferential direction. In three places. The depth of the groove portion 15 is set to a dimension that is approximately two to five times the plate thickness dimension of the riser portion 22, and the width of the groove portion 15 is set to a dimension that allows the riser portion 22 to be fitted. .

  Further, as shown in FIG. 3, protrusions 14 a are integrally formed on both sides of the groove portion 15 on the jetty portion 14 located near the base end of the cylindrical portion 11 of the insulating base 10. This protrusion 14a is formed in a conical shape as shown, and can be plastically deformed by heating. In addition to the conical shape, the protruding portion 14a may be formed in an appropriate shape such as a columnar shape, a prismatic shape, or a hemispherical shape. And the volume of each protrusion part 14a is preferably set to about one half of the volume of the opening side space formed when the riser part 22 is fitted to the groove part 15.

  Further, an arc-shaped groove 17 for receiving the lower end portion of the commutator piece 21 is formed in the base portion with the cylindrical portion 11 inside the jetty portion 14 so as to be connected to each groove portion 15. These arc-shaped grooves 17 are separated in the circumferential direction by convex portions 16 bulging radially outward from the outer peripheral surface of the cylindrical portion 11. The convex portions 16 are formed at three locations at regular intervals of about 120 degrees in the circumferential direction, and function to keep the width S of the slit 23 constant by contacting the side surfaces of the commutator piece 21 with both side surfaces. is doing.

  The commutator piece 21 has a commutator portion 20 formed in an arc shape that is in sliding contact with a brush disposed in a rotating electric machine such as a small motor (not shown), and is directed radially outward from one end side of the commutator portion 20. And a riser portion 22 that is bent. The commutator piece 21 is made of a clad material in which copper is used as a base material and a thin contact material such as Ag-Cu is embedded in a portion in sliding contact with the brush. Further, the commutator piece 21 has a radius of curvature that matches the outer peripheral surface of the cylindrical portion 11 of the insulating base 10, and its width is a predetermined distance between adjacent commutator pieces 21 when attached to the insulating base 10. A slit 23 having a width S is set to be formed. Note that an armature winding (not shown) is connected to the riser unit 22.

  Further, a washer 30 fitted on the outer periphery of the commutator piece 21 is in contact with the side surface of the cylindrical portion 11 of the jetty portion 14. The washer 30 is formed in a ring shape, and a material having an electrical insulating function or a semiconductor function such as paper, synthetic resin, or varistor is used. Furthermore, the washer 30 has an inner diameter dimension set to a size that presses and fixes the commutator piece 21 to the outer peripheral surface of the insulating base 1, and an outer diameter dimension is a bulging portion formed by plastic deformation of the protrusion 14a. It is formed in the size to cover. The washer 30 is attached to the outer peripheral surface of the insulating base 10 with the three commutator pieces 21 and then fitted from the upper end side in the drawing to press the commutator pieces 21 against the outer peripheral surface of the insulating base 10. It is fixed in the state.

  Next, the manufacturing method of the assembly type commutator which consists of this invention is demonstrated. First, as shown in FIG. 3, the three commutator pieces 21 are attached to the outer peripheral surface of the cylindrical portion 11 of the insulating base 10 in the direction indicated by the arrow. At this time, the riser portion 22 of the commutator piece 21 is fitted into the groove portion 15, the lower end portion of the commutator piece 21 is inserted into the arc-shaped groove 17 formed at the base portion of the cylindrical portion 11, and the side surface is convex. 16 is contacted. As a result, the commutator piece 21 is attached at a predetermined position while keeping the width S of the slit 23 constant.

  In this way, when the commutator piece 21 is attached to the outer peripheral surface of the cylindrical portion 11 of the insulating base 10, the riser portion 22 of the commutator piece 21 contacts the bottom surface of the groove portion 15 as shown in FIG. Fit until contacted. As described above, since the depth of the groove portion 15 is formed larger than the plate thickness dimension of the riser portion 22, the upper surface of the riser portion 22 and the opening end of the groove portion 15 are separated from each other, and a space is formed there. Has been.

  From the state in which the riser portions 22 of the three commutator pieces 20 are fitted in the groove portions 15, the protrusion portions 14 a are plastically deformed by pressing the pressing tool 40. The pressing tool 40 is heated to a predetermined temperature by, for example, an electric heater. Thus, when the heated pressing tool 40 is pressed toward the protrusion 14a, the protrusion 14a is plastically deformed as shown in FIG. 4B, and the resin of the protrusion 14a has a particularly small flow load. A bulging portion 15 a bulges in the groove portion 15 by moving into the opening side space of the groove portion 15. As a result, the base portion of the riser portion 22 fitted in the groove portion 15 is pressed by the bulging portion 15 a and fixed in the groove portion 15. At this time, as shown in the figure, the bulging portion 15a bulges into the space of the groove portion 15 so as to approach each other, and the upper surface of the jetty portion 14 is formed flat as shown in FIG. Although a gap is formed between the bulging portions 15 a, the bulging portions 15 a on both sides may be bulged until they are joined, and the bulging portions 15 a may slightly protrude from the upper surface of the jetty portion 14.

  The pressing tool 40 is pressed while the projection 14a is heated to a temperature at which plastic deformation can be performed by ultrasonic heating means, laser heating means, or the like, and the resin of the projection 14a is moved into the groove 15 so that the bulge 15a is moved. The riser part 22 may be fixed by forming.

  Thus, when the protrusion 14a is pressed and plastically deformed, the resin of the protrusion 14a moves into the groove 15 and moves toward the outer peripheral surface of the commutator 21 as shown in FIG. As a result, since the commutator piece 21 is pressed against the outer peripheral surface of the cylindrical portion 11 of the insulating base 10, the three commutator pieces 20 are firmly fixed together with the riser portion 22. Therefore, the commutator piece 21 is securely fixed by pressing and fixing by the washer 30, pressing and fixing from the outer peripheral side by plastic deformation of the protrusion 14 a, and fixing of the riser portion 22.

  By the way, the width of the groove portion 15 is set so that the riser portion 22 can be fitted, but the width of the groove portion 15 and the riser portion 22 varies in size, and the riser portion 22 fits loosely in the groove portion 15. May match. However, as described above, since the riser portion 22 fitted in the groove portion 15 is pressed and fixed by the bulging portion 15a formed by plastic deformation, the width of the groove portion 15 and the riser portion 22 varies. Can be fixed with a predetermined strength. In particular, in the case of an ultra-compact commutator having an outer diameter of the commutator portion of 3 mm or less, since the width of the groove portion 15 and the riser portion 22 is 0.5 mm or less, the fitting state between the two is large. May vary. However, even in such a very small size ultra-compact assembly type commutator, the riser portion 22 is fixed by the bulging portion 15a formed by plastic deformation, so that the variation in size with respect to fixing can be ignored. It becomes.

  Next, the washer 30 is inserted from the upper end side of the commutator piece 21 in the illustrated state until it comes into contact with the protrusion 14a in a light press-fit state, and the three commutator pieces 20 are attached to the outer peripheral surface of the cylindrical portion 11 of the insulating base 10. And the bulging portion 15a is covered. Thereby, an assembly-type commutator is manufactured.

  As described above, when the protrusion 14a is plastically deformed and pressed by pressing the pressing tool 40 heated to a predetermined temperature, when the pressing tool 40 is pulled up, as shown in FIG. A thread-like whisker 50 may occur due to misting. The whiskers 50 may scatter and adhere to the commutator 20 when disposed in a rotating electric machine such as a small motor. The whisker 50 is an electrically insulating material, and there is an accident in which energization stops when the brush 50 rides on the beard 50 with the brush attached.

  However, when the washer 30 is inserted until it comes into contact with the bulging portion 15a, the pressing force of the washer 30 compresses the whisker 50 and covers the bulging portion 15a as shown in FIG. As a result, the whisker 50 is sandwiched between the bulging portion 15a and the washer 30, and there is no gap between the inner peripheral surface of the washer 30 and the commutator piece 21, so that it passes through the commutator piece 21 side. Since this is also prevented, adhesion to the commutator 20 and scattering into the motor are prevented.

  As described above, the riser portions 22 of the plurality of commutator pieces 20 arranged and fixed on the outer peripheral surface of the insulating base 10 formed in a cylindrical shape are fitted in the grooves 15 formed in the flange portion 12 of the insulating base 10. In addition, since the protrusion 14a formed on the opening side of the groove 15 is plastically deformed by the pressing of the pressing tool 40 and the base of the riser 22 is fixed, each rectification is performed on the outer peripheral surface of the insulating base 10 with a simple configuration. The child piece 20 can be firmly disposed and fixed. Further, since the protrusion 14a is fixed by plastic deformation, the commutator piece can be reliably fixed even if the dimensions of the riser portion of the commutator piece and the groove portion of the insulating base vary. In addition, since the washer covers the bulging portion, even if a thread-like whisker occurs due to the thread pulling phenomenon after the protrusion is heated and plastically deformed, the whisker is pressed by the washer and protrudes into the commutator piece. And scattering can be prevented.

  Although the present invention has been specifically described above based on the embodiments, it is needless to say that the present invention is not limited to the above embodiments and can be variously modified without departing from the gist thereof. For example, in the above-described embodiment, the opening side of the groove portion is plastically deformed and the riser portion is fixed by a pair of left and right bulging portions, but a protrusion is formed on one of the opening sides of the groove portion, and this one piece The protruding portion may be plastically deformed and fixed by one bulging portion. Further, the number of commutator pieces is not limited to three, and may be changed to an arbitrary number of two or more. The open angle of each commutator piece is not limited to an equal angle, and is set to a different angle. May be. In this case, the arrangement angle of the protrusion is also set to a different angle. Furthermore, the shape of the groove side on the opening side is not limited to the shape of the above-described embodiment, and any shape can be used as long as the amount of resin that can bulge the bulging portion in the groove portion can be secured by plastic deformation on the opening side. Also good.

It is a top view of the assembly-type commutator concerning this invention. It is sectional drawing in FIG. It is a disassembled perspective view of the assembly-type commutator concerning this invention. (A) (B) is explanatory drawing which shows the process of fixing the riser part of the assembly-type commutator concerning this invention. It is an expanded sectional view showing the state where the riser part of the assembly type commutator concerning the present invention was fixed. It is a perspective view of the assembly-type commutator concerning this invention. It is sectional drawing which shows the state in which the beard produced in the bulging part. It is sectional drawing which shows the state which pressed the whisker produced in the bulging part with the washer. It is the disassembled perspective view which showed the structure of the conventional assembly type commutator. It is sectional drawing which showed the structure of the conventional assembly type commutator.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Insulation base | substrate 11 Cylindrical part 12 Flange part 14a Protrusion part 15 Groove part 15a Expansion part 20 Commutator piece 21 Commutator part 22 Riser part 23 Slit 30 Washer 40 Press tool 50 Whisk

Claims (4)

A plurality of commutator pieces having a commutator portion formed in an arc shape and a riser portion connected to the commutator portion are formed with slits between the respective commutator pieces on the outer peripheral surface of the cylindrical insulating base. In the assembly type commutator formed by placing and arranging a washer on the outer periphery of the commutator piece and pressing and fixing to the outer peripheral surface of the insulating base,
The insulating base is formed of a synthetic resin having thermoplasticity, and a groove portion for fitting the base portion of the riser portion is formed in the flange portion provided on the base end side,
On the opening side of the groove is formed a protrusion protruding in the riser direction,
The base part of the riser part is fixed in the groove part by a bulging part bulged in the groove part direction by plastic deformation of the protrusion part,
The assembly type commutator, wherein the washer is fitted on an outer periphery of the commutator piece, presses and fixes the commutator piece to the insulating base, and covers the bulging portion.   The washer is formed in a ring shape, an outer diameter is formed to cover the bulging portion, and an inner diameter is formed to press the commutator piece disposed on the outer peripheral surface of the insulating base. The assembly type commutator according to 1. A plurality of commutator pieces having a commutator portion formed in an arc shape and a riser portion connected to the commutator portion are formed with slits between the respective commutator pieces on the outer peripheral surface of the cylindrical insulating base. After providing and arranging, in the manufacturing method of the assembly type commutator formed by inserting a washer into the outer periphery of the commutator piece and pressing and fixing to the outer peripheral surface of the insulating base,
The base portion of the riser portion is fitted into the groove portion of the flange portion provided on the base end side of the insulating base formed of a synthetic resin having thermoplasticity,
The riser portion is fixed in the groove portion by forming a bulge portion by bulging the protrusion portion formed on the opening side of the groove portion in the direction of the groove portion by plastic deformation,
A method of manufacturing an assembly-type commutator, wherein the washer is fitted on an outer periphery of the commutator piece to press-fix the commutator piece to the insulating base and cover the bulging portion. The protrusion is bulged by plastic deformation in the direction of the riser by a pressing tool heated by a heating means, and the base of the riser is fixed in the groove by the bulge, and then the washer is fixed to the commutator piece. The manufacturing method of the assembly type commutator according to claim 3, wherein the bulging portion is covered by being fitted on an outer periphery of the commutator.

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