JP5184261B2 - Manufacturing method of commutator for rotating electrical machine - Google Patents

Description

  The present invention relates to a commutator used in a rotating electrical machine such as a DC motor or a DC generator.

  Conventionally, as a method of manufacturing a commutator used in a rotating electric machine such as a DC motor or a DC generator, a cylindrical commutator piece base material connected with commutator pieces is set in a mold, and the commutator piece base material The commutator piece base material and the resin body are integrated by injecting resin inside and insert molding to create a commutator base material, and the commutator piece base material is cut at a predetermined pitch in the circumferential direction. Thus, a method of forming a commutator in which a plurality of electrically independent commutator pieces are arranged on the outer peripheral portion is known. Although this method can ensure the arrangement accuracy of the commutator pieces and the adhesion between the commutator pieces and the resin body, the manufacturing equipment becomes larger and expensive, so the manufacturing cost of the commutator becomes higher. Tend.

  On the other hand, as a method of manufacturing a commutator at a low manufacturing cost, a plurality of fitting grooves extending in the axial direction are formed on the outer peripheral portion of a cylindrical resin body, and a commutator piece is fitted into each fitted portion. Thus, there is a method of manufacturing a commutator in which a plurality of commutator pieces are arranged on the outer periphery of the resin body. This manufacturing method is simple in manufacturing equipment and has high productivity due to a small number of manufacturing steps.

However, in this method, the accuracy of fitting the commutator piece to the resin body is insufficient, and there is a possibility that the commutator piece floats radially outward. Accordingly, a pair of sandwiching portions are formed on the outer peripheral portion of the resin body, and a pair of sandwiching portions that wrap the support portion from the outside and fit into a fitting groove formed on the base end side of the support portion. Thus, an invention has been proposed in which the commutator piece is securely fixed to the resin body (see Patent Document 1).
JP 2000-102225 A

  The commutator is integrally attached to a rotating shaft of a motor or the like, and rotates together with the rotating shaft in a state where the brush is in contact with the outer peripheral surface thereof. It is desired to be placed on a cylindrical surface. However, the commutator manufacturing method in which the commutator piece is placed on the outer periphery of the resin body by fitting the commutator piece into the resin body is superior to the manufacturing method by insert molding in terms of equipment cost and productivity. However, since a gap is easily generated between the commutator piece and the resin body, the arrangement accuracy of the commutator piece is inferior. This problem also exists in the invention of Patent Document 1.

  The present invention has been made in view of such a background, and an object of the present invention is to provide a method of manufacturing a commutator for a rotating electrical machine that has high productivity and high placement accuracy of commutator pieces.

  In order to solve the above problems, the present invention is a method of manufacturing a commutator used in a rotating electrical machine, wherein a through hole into which a rotating shaft is inserted and a circumferential direction at an outer peripheral portion parallel to the axial direction of the through hole A first mold for forming a substantially cylindrical resin body having a plurality of holding grooves disposed on the bottom and having a fitting groove formed at the bottom of the holding groove; and thermosetting A commutator piece comprising a step of molding the resin body by injecting resin into a first mold, and a brush sliding contact surface and a fitting protrusion formed on a side opposite to the brush sliding contact surface A plurality of commutator pieces, the step of arranging the plurality of commutator pieces in the plurality of holding grooves such that the fitting protrusions are fitted in the fitting grooves, and the plurality of commutator pieces are the plurality of pieces. Second mold for compression-molding the resin body disposed in the holding groove And preparing the resin body in which the plurality of commutator pieces are arranged in the plurality of holding grooves in a second mold, and compression molding at a temperature equal to or higher than the glass transition temperature of the thermosetting resin. And a step of arranging the sliding contact surface of the commutator piece on a cylindrical surface coaxial with the resin body.

  In this case, the second mold may include a columnar protrusion for forming the through hole, and the resin body may be compressed in the axial direction when the compression molding is performed.

  According to the present invention, by forming a resin body having a low curing temperature and a low glass transition temperature with the first mold, pre-molding with a thermosetting resin is performed, and the commutator piece is disposed in the holding groove. After that, the resin body is compression-molded with a second mold at a temperature equal to or higher than the glass transition temperature, whereby the resin body is plastically deformed, and the sliding contact surface of the commutator piece forms a cylindrical surface coaxial with the resin body. Since it deform | transforms and hardens | cures so that it may be arrange | positioned along this metal mold | die, the positional accuracy of the sliding contact surface of a commutator piece can be improved. In addition, since this manufacturing method does not require insert molding and does not require slit processing, simple equipment is required and investment equipment costs are reduced. Accordingly, the commutator can be manufactured at low cost, and a plurality of models of commutators having different shapes and dimensions can be easily manufactured in correspondence with various types of electric motors. Furthermore, since the manufacturing cycle time of the commutator is shortened compared to the manufacturing using insert molding, the productivity is also improved.

  Moreover, the said 2nd metal mold | die is provided with the column-shaped protrusion for shape | molding the said through-hole, and the precision of the through-hole of a resin body can be improved by compressing the said resin body to an axial direction. Thereby, the internal diameter process with respect to the through-hole of a commutator can be abbreviate | omitted, and further cost reduction and the improvement of productivity are implement | achieved.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of an electric motor device to which a commutator 10 according to this embodiment is applied. The electric motor device is an electric motor device for opening and closing a window mounted on a vehicle, and is integrated with a brushed DC motor (hereinafter simply referred to as a motor 1) and a bottomed cylindrical casing 2 that also serves as a yoke thereof. The speed reducer 3 is combined with the speed reducer 3.

  The illustrated motor 1 includes a rotor 4 rotatably received in a casing 2, and a plurality of permanent magnets 7 disposed on a corresponding inner peripheral surface of the casing 2 so as to surround the rotor 4. The DC motor has a general structure including a brush 8 that is in sliding contact with the rotor 4. The rotor 4 includes a metal rotary shaft 5 rotatably held in the casing 2, an armature 6 provided coaxially and integrally with the rotary shaft 5, and coaxial and integral with the rotary shaft 5 adjacent to the armature 6. It is comprised from the substantially cylindrical commutator 10 attached to. The brush 8 is supported by a brush holder attached to the casing 2 and is in sliding contact with the outer peripheral surface of the commutator 10.

  The rotating shaft 5 extends in the resin body of the speed reduction device 3 on the side protruding from the casing 2 and is supported by two bearings 9 a and 9 b provided in the speed reduction device 3. Further, the end of the rotating shaft 5 is pivotally supported by a bearing 9c provided on the side of the casing 2 opposite to the speed reducer 3. A worm 5a is integrally formed at an intermediate portion of the rotating shaft 5 protruding toward the speed reduction device 3, and the speed reduction device 3 is configured by a gear connection of the worm wheel 17 to the worm 5a. The shaft of the worm wheel 17 serves as an output shaft of the motor device that drives a link mechanism of a regulator for opening and closing a window (not shown).

  2 is a longitudinal sectional view of the commutator 10 according to the embodiment, and FIG. 3 is a sectional view taken along the line III-III in FIG. As shown in FIGS. 2 and 3, the commutator 10 includes a substantially cylindrical resin body 11 and a plurality of commutator pieces 12 made of copper arranged at equal intervals in the circumferential direction on the outer periphery of the resin body 11. The The resin body 11 includes a through hole 11a into which the rotating shaft 5 is inserted, a plurality of holding grooves 11b parallel to the through holes 11a formed in the outer peripheral portion for holding the commutator piece 12, and the commutator piece 12. A fitting groove 11c formed at the bottom of the holding groove 11b is provided for fitting. The commutator pieces 12 are all formed in a substantially fan-like shape, and each of them has an arcuate sliding contact surface 12 a disposed on the radially outer side (arc side) of the commutator 10, and the commutator 10. A riser 12b that protrudes radially outward at one end in the direction of the axis A, and a fitting protrusion that protrudes radially on both sides of the commutator 10 in the circumferential direction and fits into the fitting groove 11c. 12c. The commutator piece 12 is disposed in an electrically independent state, and a portion protruding from the outer peripheral surface of the resin body 11 forms a slit 13 between the commutator pieces 12 adjacent to each other.

  Next, a method for manufacturing the commutator 10 will be described. FIG. 4 is a flowchart showing a method for manufacturing the commutator 10, and FIGS. 5 to 8 are explanatory diagrams regarding the method for manufacturing the commutator 10. FIG. 5 shows the first mold 20 in a partially broken view. 6 is a cross-sectional view of the resin body 11, FIG. 7 is a vertical cross-sectional view of the commutator 10, and FIG. 8 is a cross-sectional view of the second mold 30 on which the commutator 10 is set. ing.

  First, the preparatory process for manufacturing the commutator 10 is performed (step 1). Specifically, a first through hole 11a into which the rotating shaft 5 is inserted is formed, and the first cylindrical body 11 having a plurality of fitting grooves 11c parallel to the through hole 11a is formed on the outer periphery. A mold 20 (see FIG. 5) is prepared. Moreover, the several commutator piece 12 provided with the slidable contact surface 12a, the riser 12b, and the fitting protrusion 12c is prepared. Further, a second mold 30 (see FIG. 8) for compression-molding the resin body 11 is provided so that the commutator piece 12 is disposed so that the sliding contact surface 12a is a cylindrical surface coaxial with the resin body 11. prepare.

  As shown in FIG. 5, the first mold 20 includes a middle mold 21 for molding the outer peripheral surface of the resin body 11, and an upper mold 22 and a lower mold 23 for molding both axial end faces of the resin body 11. These form a cavity 24. At the center of the lower mold 23, a post 23 a whose upper surface comes into contact with the upper mold 22 protrudes in order to mold the through hole 11 a of the resin body 11 into which the rotary shaft 5 is inserted. Although not shown, the first mold 20 includes a sprue to which the nozzle of the injection molding machine joins, a runner and gate that opens the sprue and guides the resin injected from the nozzle to the cavity, and air in the cavity 24. And air vents for discharging gas are formed.

  Next, a high-strength phenol resin is injected into the cavity 24 of the first mold 20 to mold the resin body 11 shown in FIG. 6 (step 2). As the high-strength phenolic resin, a phenolic resin using glass fiber as a reinforcing material is used. The curing temperature of the phenol resin is generally set to 160 ° C to 190 ° C. In this embodiment, the temperature of the 1st metal mold | die 20 and high intensity | strength phenol resin is set to below the general molding temperature of phenol resin (for example, 150 degreeC).

  Next, 24 commutator pieces 12 are attached to the outer periphery of the resin body 11 formed in Step 2 (Step 3). Specifically, as shown in FIG. 7, each commutator piece 12 is slid from one end in the axial direction of the resin body 11 so that the fitting protrusion 12 c is inserted into the fitting groove 11 c, thereby causing the resin body 11 to move. It attaches to the holding groove 11b formed in the outer peripheral part.

  Thereafter, the commutator 10 having the commutator piece 12 attached to the outer periphery of the preformed resin body 11 is set in the second mold 30 as shown in FIG. The resin body 11 is compression-molded by heating and pressurizing in the vertical direction (the axial direction of the resin body 11) in the figure (step 4). The second mold 30 includes an upper mold 31 having a true cylindrical inner peripheral surface 31a, and a lower mold 32 having a cylindrical guide post 33 having an outer peripheral surface 33a coaxial with the inner peripheral surface 31a. A cavity is formed by the inner peripheral surface 31a, the outer peripheral surface 33a, and the like. On the inner peripheral surface 31 a of the upper mold 31, 24 protrusions 31 b that are complementary to the slit 13 are formed. At this time, the second mold 30 is set to a temperature (for example, 200 ° C.) higher than the glass transition temperature of the high-strength phenol resin, and the resin is in a state where the guide posts 33 are inserted into the through holes 11 a of the resin body 11. The body 11 is pressurized in the vertical direction in the figure. Thereby, the resin body 11 is plastically deformed at a temperature equal to or higher than the glass transition point, the commutator piece 12 is brought into close contact with the inner peripheral surface 31 a of the upper mold 31, and the through hole 11 a of the resin body 11 is arranged on the outer periphery of the guide post 33. It is compressed and deformed so as to be in close contact with the surface 33a, and is cured by being maintained at a high temperature (for example, 200 ° C.) for a predetermined time. Although the case where the commutator piece 12 is attached to the resin body 11 and set in the second mold 30 is described above, the commutator piece 12 is attached after the resin body 11 is set in the second mold 30. It may be attached.

  Thereafter, the commutator 10 having the cured resin body 11 is taken out of the second mold 30, the local residual stress of the resin body 11 is removed, the glass transition temperature is increased, and the hardness of the commutator 10 is increased to increase the hardness. After baking is performed (step 5), the manufacturing process of the commutator 10 is completed.

  The manufactured commutator 10 is configured as the rotor 4 with the rotary shaft 5 being press-fitted into the through hole 11a, and the outer peripheral surface is cut as a finishing process.

  Thus, according to the present manufacturing method, the commutator 10 can be used as a spare for the resin body 11 by injection molding with a thermosetting resin at a temperature equal to or lower than a general molding temperature (for example, 150 ° C.) in the first mold 20. After the molding is performed and the commutator piece 12 is fitted on the outer periphery of the resin body 11, the resin is pressed by the second mold 30 at a temperature equal to or higher than the glass transition temperature (for example, 200 ° C.). Since the body 11 is compressed and deformed by plastic deformation and cured after final molding, the commutator piece 12 can be matched with the shape of the second mold. Therefore, the commutator piece 12 is arranged with high accuracy at an appropriate position. Moreover, according to this manufacturing method, the manufacturing cost can be reduced by simplifying the equipment and the productivity can be improved by shortening the manufacturing cycle time, compared to the manufacturing using insert molding.

  Further, the second mold 30 is provided with a truly cylindrical guide post 33, and the through hole 11 a of the resin body 11 is coaxial with the sliding contact surface 12 a of the commutator piece 12 by compressing the resin body 11 in the axial direction. And it is formed into a true cylinder. Thereby, the inner diameter processing of the through hole 11a with respect to the commutator 10 can be omitted, and further cost reduction and productivity improvement are realized.

  This is the end of the description of specific embodiments, but the present invention is not limited to these embodiments. For example, in the above embodiment, the commutator is applied to an electric motor device for opening and closing a window, but the application target is not limited to this, and any DC motor with a brush can be used for any purpose. It may be. The application target of the commutator is not limited to a motor that converts electrical energy into rotational kinetic energy, but may be a DC generator that converts rotational kinetic energy into electrical energy.

  Moreover, in the said embodiment, when shape | molding the resin body, the injection molding method is employ | adopted, However, You may employ | adopt methods other than this. For example, when the extrusion molding method is employed, a resin body having the same cross-sectional shape can be manufactured more easily and efficiently. Furthermore, the material of the thermosetting resin or commutator piece used as the material of the resin body is not limited to the above. In addition, the temperature at which the thermosetting resin is preformed and the temperature at which compression molding is performed can be changed according to the characteristics of the material used, the manufacturing conditions, and the like, and other than these, it does not depart from the spirit of the present invention. Any change can be made within the range.

Cross section of an electric motor device using a commutator Longitudinal section of commutator III-III cross section in Fig. 2 Flow chart showing the commutator manufacturing method The perspective view of the 1st metal mold | die shown partially broken Illustration of commutator manufacturing method Illustration of commutator manufacturing method Illustration of commutator manufacturing method

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Motor 5 Rotating shaft 8 Brush 10 Commutator 11 Resin body 11a Through-hole 11b Holding groove 11c Fitting groove 12 Commutator piece 12a Sliding contact surface 12c Fitting protrusion 13 Slit 20 First mold 30 Second mold A Axis

Claims (2)

A method of manufacturing a commutator used in a rotating electrical machine,
The through hole into which the rotating shaft is inserted, and a plurality of holding grooves arranged in the circumferential direction in the outer peripheral portion parallel to the axial direction of the through hole, and a fitting groove formed at the bottom of the holding groove Providing a first mold for molding a cylindrical resin body;
Molding the resin body by injecting a thermosetting resin into a first mold;
Preparing a plurality of commutator pieces each having a brush sliding contact surface and a fitting protrusion formed on a side opposite to the brush sliding contact surface;
Disposing the plurality of commutator pieces in the plurality of holding grooves such that the fitting protrusions are fitted in the fitting grooves;
Preparing a second mold for compression molding the resin body in which the plurality of commutator pieces are disposed in the plurality of holding grooves;
By setting the resin body in which the plurality of commutator pieces are arranged in the plurality of holding grooves to a second mold and compression-molding at a temperature equal to or higher than the glass transition temperature of the thermosetting resin, the rectification And a step of disposing a sliding contact surface of the child piece on a cylindrical surface coaxial with the resin body.   2. The method of manufacturing a commutator according to claim 1, wherein the second mold includes a columnar protrusion for forming the through hole, and compresses the resin body in an axial direction. 3. .

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