JP2010154694A - Commutator, and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a commutator, which suppresses generation of weld lines along the radial direction. <P>SOLUTION: In an insulator forming process, a segment material 11 is placed in a cavity C1 formed in a mold, and the cavity C1 is filled with a melted resin P1. At this time, the melted resin P1 is injected into the cavity C1 from the outer peripheral side of the axis L1 of the segment material 11, and flows inside the cavity C1 along the periphery of the segment material 11 to fill the cavity C1. The melted resin P1 is then hardened to be integrated with the segment material 11 to form an insulator. Then, the segment material 11 is cut at a plurality of spots along the peripheral direction in a cutting process, to form a plurality of segments arranged adjacent to each other along the peripheral direction. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method of manufacturing a commutator provided in a motor, and the commutator.

  For example, as described in Patent Document 1, a commutator has conventionally been provided with a cylindrical insulator inside a segment material by filling the segment segment material with a molten resin and curing it. After that, a plurality of segments separated in the circumferential direction are formed by cutting a plurality of portions in the circumferential direction of the segment material. The commutator manufactured in this way is fixed to the rotating shaft by press-fitting the rotating shaft of the motor into a press-fitting hole provided in the central portion in the radial direction of the insulator and penetrating in the axial direction.

  An insulator formed by curing the molten resin may have a weld line extending in the radial direction. Since this weld line lowers the tensile strength in the circumferential direction of the insulator, the insulator having the weld line may be damaged, such as a crack in the weld line when the rotary shaft is press-fitted. The breakage of the insulator contributes to the generation of noise when the motor is driven. In addition, when the rotating shaft is press-fitted into an insulator having a weld line, the insulator may be deformed at the weld line portion, and the radial position of the segments adjacent in the circumferential direction may be shifted to cause a step.

Therefore, in general, when manufacturing an insulator, a film gate is employed in a molding apparatus that fills a molten resin in a mold for molding the insulator, thereby suppressing the occurrence of weld lines. More specifically, as shown in FIGS. 10 and 11, the molding apparatus includes a bottomed cylindrical first molding die 101 and a second molding die that substantially closes the opening of the first molding die 101. 102. In the first molding die 101, a columnar molding portion 101a extending in the axial direction from the center of the bottom of the first molding die 101 is provided. A space between the inner peripheral surface of the first mold 101 and the outer peripheral surface of the molding portion 101a is a cavity for forming the insulator 104 (see FIG. 12) in which the cylindrical segment material 103 is disposed. C2. A cylindrical runner 105 is formed in the second mold 102 at a position facing the tip of the molding part 101a in the axial direction, and an opening on the cavity C2 side of the runner 105 is formed in the cavity C2. A first gate constituting portion 106 having a substantially frustoconical inner peripheral surface that is enlarged as it approaches is provided. In addition, a conical second gate component 107 is provided at the tip of the molding unit 101 a, and the second gate component 107 is disposed in the first gate component 106. A film gate 108 is configured by the first gate configuration unit 106 and the second gate configuration unit 107. The film gate 108 can inject the molten resin P2 into the cavity C2 from all directions of 360 °. And by injecting the molten resin P2 into the cavity C2 uniformly from all directions of 360 ° through the film gate 108, it is possible to suppress the formation of a weld line along the radial direction in the insulator 104 to be formed. .
JP 2002-17072 A

  However, as shown in FIG. 13, when a part of the film gate 108 is blocked by the foreign material 110 such as a lump of filler mixed in the molten resin P2 for ensuring the strength, a part of the film gate 108 is blocked by the foreign material 110. Injection of the molten resin P2 from the inside is hindered. Then, since the molten resin P2 is not uniformly injected from all directions of 360 ° in the film gate 108, in the portion where the injection of the molten resin P2 is obstructed by the foreign material 110, as shown in FIG. The molten resin P2 flows from both sides in the direction (see arrows in FIG. 12), and a mating surface of the molten resin P2 is formed. As a result, a weld line 111 along the radial direction is formed at the site where the mating surface of the molten resin P2 is generated.

  It is very difficult to find an insulator having a weld line based on appearance and dimensions. Also, in recent molding machines equipped with an automatic monitoring function for the filling peak pressure and filling time of the molten resin in the cavity, the probability that an abnormal filling of the molten resin can be detected based on the filling peak pressure and filling time has been improved. However, a slight weld line due to a minute foreign material is very difficult to detect in most cases. In particular, when a large number of insulators are taken, it is very difficult to detect the occurrence of a weld line. From these facts, it is desired to prevent the formation of weld lines along the radial direction as much as possible when forming the insulator.

  This invention is made | formed in view of such a situation, The objective is to provide the manufacturing method and commutator of a commutator which can suppress generation | occurrence | production of the weld line along radial direction.

  In order to solve the above-mentioned problems, the invention according to claim 1 is characterized in that a substantially annular segment material is disposed in a cavity formed in a mold, and a molten resin is filled in the cavity and cured to be used for the segment. An insulator forming step for forming a substantially annular insulator integrated with the material, and a cutting step for cutting a plurality of circumferential portions of the segment material to form a plurality of segments arranged in parallel in the circumferential direction; In the insulator forming step, the molten resin is injected into the cavity from the outer peripheral side of the central axis of the segment material, and the segment material is formed in the cavity. The gist is to flow and fill in the circumferential direction.

  According to the present invention, since the molten resin injected into the cavity flows and fills along the circumferential direction of the segment material in the cavity, it becomes difficult to form a mating surface of the molten resin extending in the radial direction, Generation of weld lines along the radial direction is suppressed. In the present invention, “substantially annular” includes “substantially cylindrical”.

  According to a second aspect of the present invention, in the method for manufacturing a commutator according to the first aspect, in the insulator forming step, the molten resin is injected into the cavity from a gate connected to the cavity, and The gist is that the gate is inclined with respect to a straight line that passes through the center of the opening on the cavity side of the gate and is orthogonal to the central axis of the segment material disposed in the cavity.

  According to the invention, the molten resin injected into the cavity is injected by injecting the molten resin from the gate that is inclined with respect to a straight line that passes through the center of the opening at the tip of the gate and is orthogonal to the central axis of the segment material. It can be made to flow easily along the circumferential direction of the segment material.

  According to a third aspect of the present invention, in the method for manufacturing a commutator according to the first or second aspect, in the insulator forming step, a jig for adjusting the volume of the cavity is disposed in the cavity. In the state where the molten resin is in contact with the axial end surface of the segment material in the jig, the volume of the cavity is gradually increased as the molten resin is injected into the cavity. The gist is to move the tool along the axial direction of the segment material.

  According to the invention, the volume of the cavity is gradually enlarged as the molten resin is injected into the cavity. The volume of the cavity is increased by moving the jig in a state where the molten resin is in contact with the axial end surface in the axial direction of the segment material. Therefore, the molten resin injected into the cavity can form a spiral flow along the circumferential direction of the segment material. As a result, formation of a mating surface along the radial direction in the molten resin during filling of the molten resin into the cavity is further suppressed, and generation of a weld line along the radial direction is further suppressed.

  According to a fourth aspect of the present invention, in the method of manufacturing a commutator according to the third aspect, in the insulator forming step, the jig is used as an injection direction of the molten resin around a central axis of the segment material. The gist is to move along the axial direction of the segment material while rotating along the axis.

  According to the same configuration, the jig for adjusting the volume of the cavity has the molten resin centered on the central axis of the segment material with the molten resin in contact with the axial end surface of the segment material in the jig. Since the molten resin is rotated along the injection direction, the flow of the molten resin in the circumferential direction becomes more stable, and the molten resin can be uniformly accommodated in the cavity.

  According to a fifth aspect of the present invention, in the method of manufacturing a commutator according to any one of the second to fourth aspects, in the insulator forming step, the molten resin is supplied from the gate connected to the cavity. The gate is injected into the cavity, and the gate is inclined with respect to the end surface in the axial direction of the insulator to be formed so that the end of the gate on the cavity faces the bottom side of the cavity. Is the gist.

  According to the invention, since the gate is inclined with respect to the end surface in the axial direction of the formed insulator so that the end on the cavity side faces the bottom side of the cavity, the gate is injected from the gate. The injection direction of the molten resin is stabilized, and it becomes easier to obtain the flow of the molten resin along the circumferential direction of the segment material.

  The invention according to claim 6 is a commutator comprising an insulator made of an insulating resin material and having a substantially annular shape, and a plurality of segments fixed to the insulator and arranged in parallel in the circumferential direction. The gist of the insulator is that the molten resin flowing along the circumferential direction is cured.

According to this configuration, since the insulator is a material in which the molten resin is flowed along the circumferential direction and hardened, generation of weld lines along the radial direction is suppressed.
The invention according to claim 7 is a commutator comprising an insulator made of an insulating resin material and having a substantially annular shape, and a plurality of segments fixed to the insulator and arranged in parallel in the circumferential direction, The gist of the insulator is that a reinforcing filler for reinforcing the insulator is mixed, and the reinforcing filler is oriented along the circumferential direction.

  According to this configuration, the reinforcing filler is oriented in the circumferential direction. The circumferential orientation of the reinforcing filler can be obtained by causing the molten resin for forming the insulator to flow along the circumferential direction during the molding of the insulator. And when molten resin is flowed along the circumferential direction and an insulator is formed, generation | occurrence | production of the weld line along a radial direction is suppressed. Furthermore, since the reinforcing filler is oriented in the circumferential direction, the tensile strength in the circumferential direction of the insulator is further increased.

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method and commutator of a commutator which can suppress generation | occurrence | production of the weld line along radial direction can be provided.

DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, an embodiment of the invention will be described with reference to the drawings.
FIG. 1 is a perspective view of a commutator 1 of the present embodiment. As shown in FIG. 1, the commutator 1 includes a substantially cylindrical insulator 2 made of an insulating resin material, and eight segments 3 fixed to the outer peripheral surface of the insulator 2 and arranged in parallel in the circumferential direction. It consists of and.

  The insulator 2 has a substantially cylindrical shape and is provided with a press-fit hole 2a penetrating in the axial direction at a central portion in the radial direction. The rotary shaft 4 of the motor (shown by a two-dotted line in FIG. 1) is press-fitted into the press-fitting hole 2a, whereby the commutator 1 is fixed to the rotary shaft 4 so as to be integrally rotatable.

  The insulator 2 is formed by curing a molten resin that flows spirally along the circumferential direction. Further, the resin material constituting the insulator 2 is mixed with a plurality of fillers 2b for reinforcing the insulator 2, and the fillers 2b are oriented in a spiral shape along the circumferential direction of the insulator 2. Has been. In FIG. 1, only a part of the filler 2b is shown, and the filler 2b is exaggerated.

  Each segment 3 made of copper has a substantially strip shape extending in the axial direction, and is curved along the circumferential direction of the insulator 2 at the outer periphery of the insulator 2. In addition, a groove 5 that separates adjacent segments 3 in the circumferential direction is formed between the segments 3 that are adjacent in the circumferential direction, and the grooves 5 reach the insulator 2. The eight segments 3 are provided at equiangular intervals in the circumferential direction, and in the eight segments 3, one end surface and the other end surface in the axial direction are respectively located in the same plane. Further, a connecting portion 3a extending from the one end surface toward the radially outer side is formed on one end surface in the axial direction of the segment 3 (upper end surface in FIG. 1). The wire connection portion 3a is connected to an end portion (not shown) of the motor winding.

  In addition, a plurality of embedded fixing portions 3 b arranged in parallel in the axial direction are formed on the inner side surface of each segment 3 so as to protrude radially inward. The plurality of embedded fixing portions 3b in each segment 3 have the embedded fixing portions 3b adjacent in the axial direction alternately projecting in the circumferential direction, and form an acute angle with the inner side surface of the segment 3. In addition, a locking recess 3c that is recessed toward the outside in the radial direction is formed at a substantially central portion in the circumferential direction of each embedded fixing portion 3b. Each segment 3 is prevented from falling off from the insulator 2 by having such an embedded fixing portion 3 b embedded in the insulator 2 at the periphery of the insulator 2.

Next, a method for manufacturing the commutator 1 as described above will be described. The commutator 1 of this embodiment is manufactured through a segment material forming process, an insulator forming process, a removing process, and a cutting process.
First, a segment material forming step for forming the segment material 11 (see FIG. 2) to be the segment 3 is performed. In the segment material forming step, as shown in FIG. 2, a segment plate material (not shown) having a predetermined shape formed in advance so as to have eight connecting portions 3a and a plurality of embedded fixing portions 3b is rounded into a cylindrical shape. By doing so, the segment material 11 is formed. The segment plate material of the present embodiment is made of copper. The segment material 11 thus formed has a substantially cylindrical shape, and connection portions 3a are formed at equiangular intervals in the circumferential direction on one axial end surface (the upper end surface in FIG. 2). Further, on the inner peripheral surface of the segment material 11, a plurality of embedded fixing portions 3 b are arranged in parallel along the axial direction at eight locations in the circumferential direction corresponding to the eight connection portions 3 a.

Next, an insulator forming step for forming the insulator 2 is performed. Here, with reference to FIG. 3 thru | or FIG. 5, the shaping | molding apparatus 20 used at the insulator shaping | molding process of this embodiment is explained in full detail.
FIG. 3 is a schematic configuration diagram of the molding apparatus 20. The molding apparatus 20 includes three molds (that is, a first mold 21, a second mold 22, and a third mold 23) divided in the axial direction of the insulator 2 to be formed.

  The first molding die 21 has a flat surface 21a with a flat upper surface, and the first molding die 21 is recessed so as to have an opening in the flat surface 21a. The 1st shaping | molding recessed part 21b to be arrange | positioned is formed. The first molding recess 21b has a circular shape when viewed from the opening side (see FIG. 4), and the inner diameter thereof is formed equal to the outer diameter excluding the connection portion 3a of the segment material 11, The depth is formed to be equal to the length of the segment material 11 in the axial direction (including the connection portion 3a). The first molding die 21 is provided with eight receiving recesses 21c extending radially outward from the opening of the first molding recess 21b, and the eight receiving recesses 21c The outer periphery of the molding recess 21b is provided at equiangular intervals in the circumferential direction so as to correspond to the eight connecting portions 3a. Moreover, as shown in FIG. 4, each accommodation recessed part 21c is made into the shape corresponding to the external shape of each connection part 3a, and the depth of the axial direction (the axial direction of the 1st shaping | molding recessed part 21) in the 1st shaping | molding recessed part 21b. Is formed to be equal to the width in the axial direction of the connection portion 3a of the connection portion 3a, and the width in the circumferential direction of the first molding recess 21b (the circumferential direction of the first molding recess) is equal to the width in the circumferential direction of the connection portion 3a. Are equally formed.

  Moreover, as shown in FIG. 3, the bottom surface of the first molding concave portion 21b is integrally provided with a concave portion forming portion 21d extending from the radial center toward the opening side of the first molding concave portion 21b. . The recess forming portion 21d has a columnar shape, and its outer diameter is set to a value equal to the inner diameter of the press-fitting hole 2a provided in the insulator 2. The axial length of the recess forming portion 21d is set to a value slightly shorter than the depth of the first molding recess 21b, and the tip surface of the recess forming portion 21d is a flat surface of the first molding die 21. It is located closer to the bottom of the first molding recess 21b than 21a.

  In the first molding die 21, the segment material 11 is disposed in the inner space of the first molding recess 21 b and the outer periphery of the recess forming portion 21 d when the insulator 2 is molded, and is filled with the molten resin P 1. Cavity C1. In the segment material 11 arranged in the cavity C1, eight connection parts 3a are arranged in the accommodating recesses 21c, respectively, and the surface on the second molding die 22 side in the connection parts 3a is a flat surface of the first molding recesses 21b. It is arranged in the same plane as 21a. Further, the segment material 11 has an outer peripheral surface in contact with an inner peripheral surface of the first molding recess 21b, and a lower end surface of the segment material 11 is in contact with a bottom surface of the first molding recess 21b. Further, the segment material 11 is disposed on the outer periphery of the recess forming portion 21d, and the center axis L1 thereof coincides with the center axis L2 of the recess forming portion 21d.

  The second molding die 22 has a substantially disk shape and is disposed so as to close the opening of the first molding recess 21b. The surface on the first mold 21 side in the second mold 22 is a flat first contact surface 22 a that is in contact with the flat surface 21 a of the first mold 21, and in the second mold 22. The surface on the third mold 23 side is a flat second contact surface 22b. A positioning hole 22c that penetrates the second molding die 22 in the axial direction (same as the direction of the central axis L2 of the recess forming portion 21d) is formed at a substantially central portion of the second molding die 22. As shown in FIG. 4, the positioning hole 22c has a semicircular shape in which the shape seen from the axial direction corresponds to about half of the opening of the first molding recess 21b, and in the opening on the first molding die 21 side. A first inclined surface 22d extending radially outward from a portion corresponding to the string (that is, a linear portion) is provided. The first inclined surface 22d faces the third mold 23 side and is inclined so as to move away from the first mold 21 toward the outer side in the radial direction. Then, on the side of the first inclined surface 22d on the one side in the circumferential direction (the front side in FIG. 4), a second molding recess 22e extending along the end on the one side in the circumferential direction of the first inclined surface 22d. Is recessed. The second molding recess 22e opens to the third molding die 23 side and is inclined in the same manner as the first inclined surface 22d, that is, is inclined so as to approach the first molding die 21 from the outer peripheral side toward the central portion. ing. The end of the second molding recess 22e on the first molding die 21 side opens in a substantially U shape toward the first molding die 21.

  The third mold is disposed so that the second mold 22 is interposed between the third mold and the first mold 21. The surface of the third mold 23 on the second mold 22 side is a flat third contact surface 23 a, which is in contact with the second contact surface 22 b of the second mold 22. Moreover, the 3rd shaping | molding die 23 is provided with the positioning convex part 23c which protruded in the 2nd shaping | molding die 22 side along the axial direction from the 3rd contact surface 23a. The positioning convex portion 23 c engages with the positioning hole 22 c formed in the second molding die 22 and positions the third molding die 23 in the circumferential direction and the radial direction with respect to the second molding die 22. The positioning projection 23c has a semicircular shape corresponding to the opening on the first mold 21 side of the positioning hole 22c, and the positioning projection 23c is inserted into the positioning hole 22c and engaged. , The distal end surface of the positioning convex portion 23 c is disposed in the same plane as the first contact surface 22 a of the second mold 22. Further, the side surface of the positioning convex portion 23c is provided with a second inclined surface 23d extending radially outward from a portion corresponding to the chord on the distal end surface (that is, a linear portion). The second inclined surface 23d is formed so as to correspond to the first inclined surface 22d of the positioning hole 22c, and is inclined so as to move away from the first molding die 21 toward the radially outer side. And in the state which the positioning convex part 23c was inserted in the positioning hole 22c and engaged, the 1st inclined surface 22d and the 2nd inclined surface 23d contact | abut mutually.

  Further, on the side of the second inclined surface 23d on the one side in the circumferential direction (the front side in FIG. 4), a third molding recess 23e extending along one end in the circumferential direction of the second inclined surface 23d. Is recessed. The third molding recess 23e opens to the second molding die 22 side and is inclined in the same manner as the second inclined surface 23d, that is, is inclined so as to approach the first molding die 21 from the outer peripheral side toward the central portion. ing. The end of the third molding recess 23e on the first molding die 21 side opens in a substantially U shape toward the first molding die 21. Further, the third mold 23 is formed with a runner 24 that is a hole extending in the axial direction so as to be connected to the end of the third mold recess 23e opposite to the first mold 21.

  When the positioning projections 23c are engaged with the positioning holes 22c and the second molding die 22 and the third molding die 23 are combined, the second molding recess 22e and the third molding recess 23e face each other in the axial direction. A hole-like gate 25 is formed by the second molding concave portion 22e and the third molding concave portion 23e with the openings being combined. The gate 25 is connected to the runner 24 at the end opposite to the first mold 21. Further, a pin gate is employed in the molding apparatus 20 of the present embodiment, and the diameter of the gate 25 is gradually reduced as the first molding die 21 is approached. Furthermore, the end of the second molding recess 22e on the first molding die 21 side and the end of the third molding recess 23e on the first molding die 21 side are combined to form an elliptical opening 25a. The opening 25a opens to the bottom side of the first molding recess 21b, and when the insulator 2 is molded, the opening 25a is on the axial end surface of the insulator 2 to be formed on the opening side of the first molding recess 21b. Placed in position.

  As shown in FIG. 5A, when viewed from the direction of the central axis L2 of the recess forming portion 21d, the gate 25 is displaced with respect to the radial direction of the segment material 11 disposed in the first forming recess 21b. It extends. Specifically, the gate 25 passes through the center of the opening 25a at the end of the gate 25 on the side of the cavity C1 and the straight line L3 perpendicular to the central axis L1 of the segment material 11 disposed in the cavity C1 The center line L4 of the gate 25 is formed to be inclined by an angle θ. Therefore, the tip of the gate 25 on the cavity C1 side is directed in a direction shifted from the central axis L2 of the recess forming portion 21d (that is, the same as the central axis L1 of the segment material 11).

  Further, as shown in FIG. 5B, when viewed from the radial direction of the recess forming portion 21d, the gate 25 is displaced with respect to the radial direction of the segment material 11 disposed in the first molding recess 21b. It extends. Specifically, the gate 25 is formed with the insulator 2 formed so that the end of the gate 25 on the cavity C1 side faces the bottom of the cavity C1 (that is, the bottom of the first molding recess 21b (see FIG. 3)). The center line L4 of the gate 25 is formed so as to be inclined by an angle α with respect to the end face in the axial direction. In FIG. 5 (b), the insulator 2 is not shown, but the dotted line is located at a position where the axial position is the same as the axial end face of the insulator 2 on the first molding recess 21b side. A straight line L5 is illustrated. The straight line L5 is in the same plane as the end surface in the axial direction on the first molding recess 21b side in the insulator 2 to be formed.

  As shown in FIG. 3, the molding apparatus 20 includes an ejector 26 for taking out the formed insulator 2 together with the segment material 11 from the first molding recess 21b, and the ejector 26 has a volume of the cavity C1. It can be adjusted (enlarged / reduced). The ejector 26 is integrally formed with a bottomed cylindrical adjustment portion 27 and a moving shaft 28 for moving the adjustment portion 27 along the axial direction. The first molding die 21 is formed with an annular guide portion 21f that is recessed along the axial direction from the bottom surface of the first molding recess 21b on the outer periphery of the recess forming portion 21d. 27 is configured to be inserted into the cavity C1 while being guided by the guide portion 21f. The insertion portion 27a is formed such that its axial length is longer than the depth of the first molding recess 21b, its inner diameter is slightly larger than the outer diameter of the recess formation portion 21d, and its outer diameter is the segment material. 11 is slightly smaller than the inner diameter. Accordingly, the insertion portion 27a does not contact the segment material 11 disposed in the first molding recess 21b. Further, the insertion portion 27a is arranged coaxially with the recess forming portion 21d, and airtightness between the inner and outer peripheral surfaces of the insertion portion 27a and the inner peripheral surface of the guide portion 21f is ensured. It has become.

  A shaft guide portion 21g on which the moving shaft 28 is disposed is formed at a portion inside the guide portion 21f in the first mold 21. The shaft guide portion 21g extends along the axial direction and has an inner diameter that is substantially equal to the outer diameter of the moving shaft 28, and allows the moving shaft 28 to move in the axial direction. Further, a portion between the guide part 21f and the shaft guide part 21g in the first molding die 21 is inserted into the bottom part of the adjustment part 27, and the guide part 21f and the shaft guide part 21g in the first mold 21 are inserted. An insertion hole 27b that enables relative movement between the portion between the ejector 26 and the ejector 26 is formed.

  A drive mechanism 32 driven by a servo motor 31 is connected to the moving shaft 28, and when the servo motor 31 is driven, the ejector 26 is moved along the axial direction via the drive mechanism 32. The As a result, the insertion portion 27a is moved in and out of the cavity C1, and the volume of the cavity C1 is changed by the ejector 26.

  The second mold 22 is provided with a pressure sensor 33 for detecting the resin pressure in the cavity C1. The pressure sensor 33 detects the resin pressure in the cavity C <b> 1 and outputs the detection result to the control unit 34 of the molding apparatus 20. The control unit 34 controls the driving of the molding apparatus 20 and controls the servo motor 31 according to the resin pressure in the cavity C1 output from the pressure sensor 33 when the insulator 2 is molded. Control the speed of changing the volume. Further, the control unit 34 controls a driving device (not shown) that moves the second molding die 22 and the third molding die 23 relative to the first molding die 21.

  In the insulator molding step performed using the molding apparatus 20 described above, first, the segment material is placed in the first molding recess 21b in which the first molding die 21 and the second molding die 22 are separated and the opening is opened. 11 is arranged. Thereafter, the second molding die 22 and the third molding die 23 are moved to the first molding die 21 side, the first contact surface 22a is brought into contact with the flat surface 21a, and the first molding recess 21b is closed. At this time, the ejector 26 is disposed at a position where the distal end surface of the insertion portion 27a is substantially equal to the distal end surface of the recess forming portion 21d.

  Next, as shown in FIG. 6A, the molten resin P1 injected from the injection device (not shown) flows into the runner 24 through the sprue (not shown), and further passes through the runner 24 to the cavity from the gate 25. It is injected into C1. The molten resin P1 is an insulating resin material containing a phenol resin, and a reinforcing filler 2b is mixed therein. 6 (b) and 6 (c), the molten resin P1 is in contact with the axial end surface of the adjustment portion 27 on the opening side of the first molding recess 21b (that is, the adjustment portion 27). With the molten resin P1 placed on the upper end surface), as the molten resin P1 is injected into the cavity C1, the ejector 26 is lowered to gradually expand the volume of the cavity C1. The expansion of the volume of the cavity C1 by the ejector 26 is performed by adjusting the descending speed of the ejector 26 according to the detection result of the resin pressure in the cavity C1 by the pressure sensor 33.

  Here, in the molding apparatus 20 of the present embodiment, the gate 25 passes through the center of the opening 25a at the tip of the gate 25 on the cavity C1 side, and the center axis L1 of the segment material 11 disposed in the cavity C1. A center line L4 of the gate 25 is formed to be inclined by an angle θ with respect to a straight line L3 orthogonal to the line L3. Further, the gate 25 is formed of the insulator 2 formed so that the end of the gate 25 on the cavity C1 side faces the bottom of the cavity C1 (that is, the bottom of the first molding recess 21b (see FIG. 3)). The center line L4 of the gate 25 is formed so as to be inclined by an angle α with respect to the end face in the axial direction. Therefore, as shown in FIG. 7, the molten resin P1 injected from the gate 25 flows along the circumferential direction in the cavity C1. In FIG. 7, the flowing direction of the molten resin P1 is shown by arrows. Further, as shown in FIGS. 6A to 6C, the molten resin P1 flows and fills in a spiral shape by lowering the ejector 26 and gradually increasing the volume of the cavity C1. For this reason, it is difficult to form a weld line along the radial direction. In FIGS. 6A to 6C, the molten resin P1 is schematically illustrated as a coil spring so that the spiral flow of the molten resin P1 can be easily understood. Further, the molten resin P1 flows and fills in a spiral shape along the circumferential direction of the segment material 11, whereby the filler 2b in the molten resin P1 is also oriented spirally along the circumferential direction.

  The ejector 26 is lowered until the distal end surface of the insertion portion 27a is disposed in the same plane as the bottom surface of the first molding recess 21b, that is, the ejector 26 is lowered until the volume of the cavity C1 is maximized, so that the segment material When the melted resin P1 is sufficiently filled in 11, the injection of the melted resin P1 is stopped. Thereafter, the molten resin P1 is cured to form the insulator 2 inside the segment material 11. In this insulator 2, a press-fitting hole 2a (see FIG. 1) extending along the axial direction is formed in the central portion in the radial direction by the concave-forming portion 21d. At this time, the concave portion is formed in the press-fitting hole 2a. The portion on the tip side of the portion 21d is closed by a closing portion 2c (shown by a two-dot chain line in FIG. 4) formed by curing the molten resin P1.

  After the molten resin P1 is cured and the insulator 2 is formed, the second mold 22 and the third mold 23 are separated from the first mold 21, and the ejector 26 is further lifted to raise the insulator. 2 is pushed out by the ejector 26, and the insulator 2 together with the segment material 11 is taken out from the first molding recess 21b. The extracted insulator 2 is integrally provided with a molten resin P1 solidified in the runner 24 and the gate 25 (see FIG. 4).

  Next, a removal step of removing an unnecessary resin molded portion from the insulator 2 is performed. The unnecessary resin molded parts are the molten resin P1 solidified in the runner 24 and the gate 25, and the closed part 2c. By removing these unnecessary resin molded portions, the insulator 2 has a cylindrical shape having a press-fitting hole 2a penetrating the central portion in the radial direction in the axial direction (see FIG. 1).

  Next, a cutting process is performed in which a plurality of portions in the circumferential direction of the segment material 11 are cut to form the segments 3. In the cutting step, a groove 5 reaching the insulator 2 from the outer peripheral side of the segment material 11 is formed along the axial direction by cutting as shown in FIG. The grooves 5 are respectively formed between the adjacent connection portions 3a. Thereby, the segment material 11 is divided into eight in the circumferential direction to form eight segments 3, and the segments 3 adjacent in the circumferential direction are separated by the grooves 5. When this cutting process is completed, the commutator 1 is completed.

As described above, according to the present embodiment, the following operational effects are obtained.
(1) Since the molten resin P1 injected into the cavity C1 flows and fills along the circumferential direction of the segment material 11 in the cavity C1, it is difficult to form a mating surface of the molten resin P1 extending in the radial direction. Thus, the generation of the weld line along the radial direction is suppressed when the insulator 2 is molded. Therefore, when the rotary shaft 4 is press-fitted into the press-fitting hole 2a, the insulator 2 is not easily damaged even if a circumferential tensile force is applied.

  (2) The gate 25 passes the center of the opening 25a at the tip of the gate 25 on the cavity C1 side, and the straight line L3 orthogonal to the central axis L1 of the segment material 11 disposed in the cavity C1 The center line L4 of the gate 25 is formed to be inclined by an angle θ. Therefore, by injecting the molten resin P1 from such a gate 25, the molten resin P1 injected into the cavity C1 can easily flow along the circumferential direction of the segment material 11.

  (3) The volume of the cavity C1 is gradually expanded as the molten resin P1 is injected into the cavity C1. And the expansion of the volume of the cavity C1 moves the ejector 26 in the state where the molten resin P1 is in contact with the axial end surface of the adjustment portion 27 on the opening side of the first molding recess 21b in the axial direction of the segment material 11. Is done. Therefore, the molten resin P1 injected into the cavity C1 can form a spiral flow along the circumferential direction of the segment material 11. As a result, formation of a mating surface along the radial direction on the molten resin P1 when the molten resin P1 is filled into the cavity C1 is further suppressed, and generation of weld lines along the radial direction is further suppressed.

  (4) The gate 25 is formed so that the end of the gate 25 on the cavity C1 side faces the bottom side of the cavity C1 (that is, the bottom side of the first molding recess 21b (see FIG. 3)). The center line L4 of the gate 25 is formed so as to be inclined by an angle α with respect to the end face in the axial direction. Therefore, the injection direction of the molten resin P1 injected from the gate 25 is stabilized, and it becomes easier to obtain the flow of the molten resin P1 along the circumferential direction of the segment material 11.

  (5) In the insulator molding step, since the molten resin P1 flows in a spiral shape along the circumferential direction of the segment material 11, the reinforcing filler 2b spirals along the circumferential direction of the insulator 2. Oriented. Since the reinforcing filler 2b is oriented in a spiral shape along the circumferential direction in this manner, the tensile strength in the circumferential direction of the insulator 2 is increased, so that the press-fit limit of the rotating shaft 4 in the insulator 2 is increased. To do. Furthermore, since the filler 2b is oriented in the circumferential direction, the dimensional change in the radial direction due to the thermal expansion and contraction of the insulator 2 can be suppressed, so that the occurrence of a radial step between the adjacent segments 3 is suppressed. Can do.

  (6) Expansion of the volume of the cavity C1 by the ejector 26 is performed by adjusting the descending speed of the ejector 26 according to the detection result of the resin pressure in the cavity C1 by the pressure sensor 33. Therefore, a rapid decrease in the viscosity of the molten resin P1 is suppressed.

In addition, you may change embodiment of this invention as follows.
In the above embodiment, the insulator 2 is mixed with the filler 2b for reinforcement. However, the insulator 2 may be configured without the filler 2b.

  In the above embodiment, the ejector 26 is moved only along the axial direction of the segment material 11. However, as in the example shown in FIGS. 8A and 8B, the ejector 65 may be rotated while being moved along the axial direction. In FIGS. 8A and 8B, the same components as those in the above embodiment are denoted by the same reference numerals. A plurality of support portions 62 (only two are shown in FIG. 8A) are erected on the upper surface of the base 61 of the molding apparatus 60 shown in FIG. The first molding die 63 is fixed to the part, and the first molding die 63 is supported by a plurality of support portions 62. The upper surface of the first mold 63 is a horizontal and flat flat surface 63a, and the segment material 11 is recessed at the center of the first mold 63 so as to have an opening in the flat surface 63a. A first molding recess 63b to be disposed is formed. The first molding recess 63b has a circular shape when viewed from the opening side, and its inner diameter is formed to be equal to the outer diameter excluding the connection portion 3a of the segment material 11, and the depth thereof is the segment. It is formed to be equal to the axial length of the material for use 11 (including the connection portion 3a). The first molding die 63 is provided with eight housing recesses 21c extending radially outward from the opening of the first molding recess 63b, and from the bottom surface of the first molding recess 63b in the axial direction. An insertion hole 63c penetrating the first mold 63 is formed along. A portion on the distal end side of a cylindrical recess forming portion 64 that is fixed to the upper surface of the base 61 and extends upward from the upper surface is inserted into the insertion hole 63c. The recess forming portion 64 is disposed so as to be coaxial with the first molding recess 63b through the central portion in the radial direction of the insertion hole 63c, and the front end surface of the recess forming portion 64 is the first molding recess 63b. It is located on the bottom side of the first molding recess 63b from the opening. The center axis L1 of the segment material 11 arranged in the first molding recess 63b and the center axis of the recess forming portion 64 coincide with each other, and the outer peripheral surface of the recess forming portion 64 and the inner periphery of the first molding die 63 are aligned. A space between the surfaces is a cavity C1.

  In addition, an ejector 65 that is movable in the axial direction with respect to the recess forming portion 64 and rotatable in the circumferential direction with respect to the recess forming portion 64 is extrapolated in the recess forming portion 64. The ejector 65 includes a cylindrical insertion portion 65a and a flange portion 65b extending radially outward from the lower end portion of the insertion portion 65a. The axial length of the insertion portion 65a is formed slightly shorter than the length obtained by subtracting the depth of the first molding concave portion 63b from the axial length of the concave portion forming portion 64. Further, the inner diameter of the insertion portion 65a is formed substantially equal to the outer diameter of the recess forming portion 64, and the outer diameter of the insertion portion 65a is formed substantially equal to the inner diameter of the insertion hole 63c. Upper ends of a plurality of support shafts 66 (only two are shown in FIG. 8A) extending to the base side are fixed to the flange portion 65b, and these support shafts 66 are provided on the base 61. The base 61 is passed through the guide hole 61a. Further, the lower ends of the plurality of support shafts 66 are fixed to and connected by a substantially disc-shaped connecting portion 67. Between the outer peripheral surface of each support shaft 66 and the inner peripheral surface of each guide hole 61a, a cylindrical sleeve 68 is provided for smooth movement of the support shaft 66 in the axial direction with respect to the guide hole 61a. .

  A linear drive motor 72 is connected to the connecting portion 67 via a linear drive mechanism 71, and a rotational drive motor 74 is connected via a rotational drive mechanism 73. When the linear drive motor 72 is driven, the linear drive mechanism 71 is driven by the driving force of the motor 72, and the connecting portion 67 and the support shaft 66 are moved along the axial direction of the recess forming portion 64 by the linear drive mechanism 71. Is done. Accordingly, the ejector 65 is moved along the axial direction while being guided by the recess forming portion 64, and the volume of the cavity C1 is changed depending on the axial position of the insertion portion 65a. On the other hand, when the rotational drive motor 74 is driven, the rotational drive mechanism 73 is driven by the driving force of the motor 74, and the connecting portion 67 is rotated by the rotational drive mechanism 73. Along with the rotation of the connecting portion 67, the ejector 65 together with the support shaft 66 rotates in the circumferential direction around the concave portion forming portion 64, that is, around the central axis L1 of the segment material 11 arranged in the first molding concave portion 63b. Is done. The driving of the linear drive motor 72 and the rotary drive motor 74 is controlled by the control unit 75 of the molding apparatus 60. In addition, airtightness is ensured between the inner peripheral surface of the insertion hole 63c and the outer peripheral surface of the insertion portion 65a, and between the inner peripheral surface of the insertion portion 65a and the outer peripheral surface of the recess forming portion 64, respectively. . On the 1st shaping | molding die 63, the 2nd shaping | molding die 22 and the 3rd shaping | molding die 23 similar to the said embodiment are arrange | positioned.

  In the insulator molding process using the molding device 60 as described above, first, the segment material is placed in the first molding recess 63b in which the first molding die 63 and the second molding die 22 are separated and the opening is opened. 11 is arranged. Then, the 2nd shaping | molding die 22 and the 3rd shaping | molding die 23 are moved to the 1st shaping | molding die 63 side, and the opening part of the 1st shaping | molding recessed part 63b is obstruct | occluded. At this time, the ejector 65 is disposed at a position where the distal end surface of the insertion portion 65 a is disposed in the same plane as the distal end surface of the recess forming portion 64.

  Next, the molten resin P <b> 1 injected from the injection device (not shown) is injected from the gate 25 into the cavity C <b> 1 through the sprue (not shown) and the runner 24. The molten resin P <b> 1 flows along the circumferential direction in the cavity C <b> 1 by being injected from the gate 25 similar to the above embodiment. Then, as shown in FIG. 8B, the ejector 65 is in a state where the molten resin P1 injected to the distal end surface of the insertion portion 65a is in contact with the gate 25 as the molten resin P1 is injected into the cavity. The molten resin P1 is lowered while being rotated about the central axis L1 of the segment material 11 along the injection direction of the molten resin P1. Accordingly, the cavity C1 is gradually enlarged, and the injected molten resin P1 is deposited spirally along the circumferential direction of the segment material 11. Accordingly, the filler 2b (see FIG. 7) contained in the molten resin P1 is also oriented spirally along the circumferential direction of the segment material 11. Then, when the volume of the cavity C1 becomes equal to the volume of the insulator 2 formed, the lowering and rotation of the ejector 65 are stopped, and in this state, the molten resin P1 is cured and the insulator 2 is formed.

  In this way, the ejector 65 is rotated along the injection direction of the molten resin P1 about the central axis L1 of the segment material 11 in a state where the molten resin P1 injected to the distal end surface of the insertion portion 65a is in contact. Therefore, the flow in the circumferential direction of the segment material 11 in the molten resin P1 is more stable. Accordingly, the molten resin P1 can be accommodated uniformly in the cavity C1, and the generation of weld lines along the radial direction is further suppressed. Note that the rotation and lowering of the ejector 65 are caused by the spiral shape of the molten resin P1 when the speed is adjusted according to the resin pressure in the cavity C1 detected using the pressure sensor 33 as in the above embodiment. The flow can be made more organized.

  Further, in the molding apparatus 20 of the above embodiment, the ejector 26 is rotated along the injection direction of the molten resin P1 around the central axis L1 of the segment material 11 arranged in the first molding recess 21b. Also good. In the insulator molding process using the molding device 20, the molten resin P1 is in contact with the axial end surface of the first molding recess 21b in the adjustment unit 27 (that is, on the upper end surface of the adjustment unit 27). In the state where the molten resin P1 is placed), the ejector 26 is moved along the axial direction of the segment material 11 while rotating along the injection direction of the molten resin P1 around the central axis L1 of the segment material 11. As shown in FIG. 5 (a), when the segment material 11 arranged in the first molding recess 21b is viewed from the gate 25 side, the gate 25 has its tip end directed in the clockwise direction. It is inclined by an angle θ with respect to the straight line L3. Accordingly, in the insulator molding process using the molding apparatus 20, since the molten resin P1 is injected clockwise from the gate 25, the ejector 26 is rotated clockwise along the injection direction of the molten resin P1. Even if it does in this way, the effect similar to the case where an insulator shaping | molding process is performed using the shaping | molding apparatus 60 can be acquired.

  In the above embodiment, the volume of the cavity C1 is adjusted by the ejector 26. However, as shown in FIG. 9, the insulator forming step may be performed with the volume of the cavity C1 being constant. In FIG. 9, the same components as those in the above embodiment are given the same reference numerals. Even in this case, as shown in FIGS. 5A and 5B, the gate 25 is formed such that the center line L4 thereof is inclined by the angle θ with respect to the straight line L3, and further formed. Since the center line L4 is formed so as to be inclined by an angle α with respect to the axial end face of the insulator 2 to be melted, the molten resin P1 injected into the cavity C1 from the gate 25 obtains a circumferential flow. be able to. Therefore, generation of a weld line along the radial direction can be suppressed.

  In the above embodiment, as shown in FIG. 5B, the gate 25 has an opening 25a at the tip of the gate 25 with respect to the axial end surface of the insulator 2 to be formed. It is inclined to face the bottom side. However, the gate 25 may be formed so as to be parallel to the axial end face of the insulator 2 to be formed, that is, so that the angle α is 0 ° perpendicular to the central axis L1 of the segment material 11.

  In the above embodiment, the gate 25 is a pin gate, but is not limited thereto. The gate 25 passes through the center of the opening 25a at the tip on the cavity C1 side of the gate 25 so that the molten resin P1 flows in the circumferential direction in the cavity, and the segment material 11 is disposed in the cavity C1. Any shape that allows the molten resin P1 to be injected at an angle θ with respect to the straight line L3 orthogonal to the central axis L1 may be used. For example, the gate 25 may be formed to have a hole shape with a constant inner diameter.

  In the above embodiment, the ejector 26 is moved along the axial direction by the driving force of the servo motor 31 being transmitted by the drive mechanism 32. However, the mechanism for moving the ejector 26 in the axial direction is not limited to this.

  The ejector 26 is not limited to the shape of the above embodiment as long as the volume of the cavity C1 can be enlarged or reduced in the axial direction. Moreover, the jig | tool which expands / reduces the volume of the cavity C1 to an axial direction is not restricted to the ejector used in order to take out the insulator 2 from the 1st shaping | molding recessed part 21b, You may provide separately from this ejector.

In the above embodiment, the molding apparatus 20 includes the pressure sensor 33 that measures the resin pressure in the cavity C1, but may be configured without the pressure sensor 33.
In the above embodiment, it is described that one insulator 2 is molded at a time in the insulator molding step, but a large number of insulators 2 may be taken.

  In the above embodiment, the commutator 1 includes eight segments 3 arranged in parallel on the outer periphery of the cylindrical insulator 2. However, the configuration of the commutator is not limited to this, and a plurality of segments may be arranged in parallel in the circumferential direction on one axial end surface of the annular insulator. Even in such a commutator, the molten resin for forming the insulator is caused to flow along the circumferential direction during the molding of the insulator, thereby suppressing the occurrence of weld lines along the radial direction. Further, the lower figure of the segment 3 provided in the commutator 1 is not limited to eight.

The technical ideas that can be grasped from each of the above embodiments and each of the above modifications will be described below.
(A) The commutator according to claim 7, wherein the reinforcing filler is oriented in a spiral along the circumferential direction of the insulator. According to this configuration, the reinforcing filler is oriented spirally along the circumferential direction of the insulator. The helical orientation of the reinforcing filler can be obtained by causing the molten resin for forming the insulator to flow in a spiral along the circumferential direction when the insulator is formed. When the insulator is formed by flowing the molten resin in a spiral shape along the circumferential direction, the generation of weld lines along the radial direction is further suppressed.

The perspective view of a commutator. The perspective view of the raw material for segments. The schematic block diagram of a shaping | molding apparatus. The disassembled perspective view of a shaping | molding die. (A) And (b) is explanatory drawing for demonstrating the angle of a gate. (A)-(c) is explanatory drawing for demonstrating the manufacturing method of a commutator. Explanatory drawing for demonstrating the flow of the molten resin in this embodiment. (A) And (b) is a schematic block diagram of the shaping | molding apparatus of another form. Explanatory drawing for demonstrating the manufacturing method of the commutator of another form. Explanatory drawing for demonstrating the manufacturing method of the conventional commutator. Sectional drawing of the conventional shaping | molding die (XX cross section in FIG. 10). The top view of the commutator formed by the conventional manufacturing method. Explanatory drawing for demonstrating the manufacturing method of the conventional commutator.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Commutator, 2 ... Insulator, 2b ... Filler as reinforcement filler, 3 ... Segment, 11 ... Segment material, 21, 63 ... 1st shaping | molding die which comprises a shaping | molding die, 25 ... Gate, 25a ... Tip Opening as opening, 26, 65 ... ejector as jig, C1 ... cavity, L1 ... central axis of segment material, L3 ... straight line, P1 ... molten resin.

Claims (7)

An insulator in which a substantially annular segment material is disposed in a cavity formed in a mold, and a molten resin is filled in the cavity and cured to form a substantially annular insulator integrated with the segment material. Molding process;
A method of manufacturing a commutator comprising a cutting step of cutting a plurality of locations in the circumferential direction of the segment material to form a plurality of segments arranged in parallel in the circumferential direction,
In the insulator molding step, the molten resin is injected into the cavity from the outer peripheral side of the central axis of the segment material, and flows and is filled in the cavity along the circumferential direction of the segment material. A method for manufacturing a commutator. In the manufacturing method of the commutator according to claim 1,
In the insulator molding step, the molten resin is injected into the cavity from a gate connected to the cavity, and the gate passes through the center of the tip opening on the cavity side of the gate and into the cavity. A method of manufacturing a commutator, wherein the commutator is inclined with respect to a straight line orthogonal to the central axis of the arranged segment material. In the manufacturing method of the commutator according to claim 1 or 2,
In the insulator molding step, a jig for adjusting the volume of the cavity is disposed in the cavity, and the molten resin is in contact with the axial end surface of the segment material in the jig. A method of manufacturing a commutator, wherein the jig is moved along the axial direction of the segment material so that the volume of the cavity is gradually enlarged as the gas is injected into the cavity. In the manufacturing method of the commutator according to claim 3,
In the insulator forming step, the jig is moved along the axial direction of the segment material while rotating along the injection direction of the molten resin around the central axis of the segment material. A method for manufacturing a commutator. In the manufacturing method of the commutator according to any one of claims 2 to 4,
In the insulator molding step, the molten resin is injected from the gate connected to the cavity into the cavity, and the gate is such that the end of the gate of the gate faces the bottom side of the cavity. A method of manufacturing a commutator, wherein the commutator is inclined with respect to an end face in an axial direction of the insulator to be formed. A commutator comprising an insulator made of an insulating resin material and having a substantially annular shape, and a plurality of segments fixed to the insulator and arranged in parallel in the circumferential direction,
The insulator is a commutator obtained by curing a molten resin that flows along a circumferential direction. A commutator comprising an insulator made of an insulating resin material and having a substantially annular shape, and a plurality of segments fixed to the insulator and arranged in parallel in the circumferential direction,
A method of manufacturing a commutator, wherein the insulator is mixed with a reinforcing filler for reinforcing the insulator, and the reinforcing filler is oriented along a circumferential direction.

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