JP5292176B2 - Compound gear manufacturing method - Google Patents

Abstract

A technology suitable for producing a high-accuracy compound gear is provided. A compound gear can be produced via a groove forming process, an engaging process, and a loading process. In the groove forming process, a groove extending in the axial direction of a first gear is formed in the peripheral surface of a hub. In the engaging process, a second gear having a center hole is engaged with the hub. In the loading process, a load in the axial direction is locally applied to a spot portion of the second gear which is opposed to the groove until the surrounding area of the center hole of the second gear is plastically flown in the groove.

Description

  The present invention relates to a method of manufacturing a compound gear in which a second gear is coaxially fixed to a hub of a first gear.

  A gear having a ring fixed to a gear hub is known. In a conventional gear, a method is often used in which an axial load is applied to a ring that is passed through a hub, and the ring is fixed to the hub of the gear by plastic deformation of the ring. A method of fixing two members by a plastic flow phenomenon is called plastic coupling. In Patent Document 1, in order to firmly fix the ring (coupling member) to the hub (member to be joined), a groove is formed on the peripheral surface of the hub of the gear, and the inner peripheral surface of the ring passing through the hub is in the groove. A technique is disclosed in which an axial load is applied to the ring until it plastically flows and both are firmly bonded.

Japanese Utility Model Publication No.59-85644

  In the technique of Patent Document 1, when a load is applied to the ring, the inner peripheral surface side of the ring is uniformly loaded in the circumferential direction. Therefore, an excessive force is applied to a portion of the peripheral surface of the hub where no groove is formed. As a result, the gear or the gear hub is deformed. When a compound gear is manufactured using the technique of Patent Document 1, the axes of the first gear and the second gear are displaced, and the roundness of the first gear and / or the second gear is reduced. Therefore, it is difficult to manufacture a high-precision compound gear only by using the technique of Patent Document 1. The present specification provides a technique suitable for manufacturing a high-precision compound gear.

  According to the technology disclosed in the present specification, it is possible to manufacture a compound gear in which the second gear is coaxially fixed to the hub of the first gear. The manufacturing method includes a groove forming step, a fitting step, and a loading step. In the groove forming step, a groove extending in the axial direction of the first gear is formed on the peripheral surface of the hub. In the fitting step, the second gear having the center hole is fitted to the hub of the first gear. In the loading step, a load in the axial direction is locally applied to the spot portion of the second gear facing the groove formed in the hub. In the loading step, a load is applied until the periphery of the center hole of the second gear plastically flows into the groove formed in the hub.

  According to the above manufacturing method, the force applied from the second gear to the first gear when a load is applied can be reduced as compared with the conventional method. That is, it is possible to suppress an excessive force from being applied to a portion where the groove is not formed on the peripheral surface of the hub of the first gear. Therefore, deformation of the first gear can be suppressed, and a highly accurate compound gear can be manufactured. The “spot part” means a part around the center hole of the second gear. Further, “a load is locally applied to the spot portion” means that a load is applied to the spot portion, but no load is applied to a portion adjacent to the spot portion along the circumferential direction.

  The thickness of the second gear in the spot portion is preferably thicker than the thickness on the radially outer side than the spot portion. When the spot portion is loaded and the second gear plastically flows into the groove formed in the hub of the first gear, the thickness of the second gear at the spot portion becomes thinner than before the load. When the thickness of the second gear before the load is uniform throughout, there is a possibility that the thickness of the loaded portion is thinner than the other portions. That is, there is a possibility that the thickness of the inner portion in the radial direction of the second gear is thinner than the outer portion. If the thickness of the second gear in the spot portion is larger than the thickness on the radially outer side than the spot portion, it is possible to avoid that the thickness of the radially inner portion becomes thinner than the thickness of the outer portion.

  In the groove forming step, it is preferable to form the groove of the hub and the tooth groove of the first gear in a straight line in the axial direction in one step. Thereby, a groove | channel formation process can be completed simultaneously with forming a 1st gearwheel in the gear blank before a 1st gearwheel is formed. A compound gear can be manufactured with few steps.

  When the groove of the hub and the tooth groove of the first gear are formed in a straight line in the axial direction in one step, the first gear is observed in the axial direction with the second gear fitted to the hub of the first gear. Of the inner peripheral surface of the second gear, the position overlapping the tooth groove of the first gear is preferably opposed to the groove of the hub. In other words, "the position of the inner peripheral surface of the second gear that overlaps the tooth groove of the first gear" means that the first gear and the second gear of the inner peripheral surface of the second gear do not overlap. Means part. In this case, the inner peripheral surface of the second gear is in contact with the hub at a position where the tooth tip of the first gear overlaps (a portion where the first gear and the second gear overlap). By applying a load to the spot portion that overlaps with the tooth groove of the first gear, it is possible to apply a concentrated load to the portion of the inner peripheral surface of the second gear that faces the groove formed in the groove forming step. it can. And it can prevent that a load is added to the part which is contacting the hub of the 1st gear among the inner peripheral surfaces of the 2nd gear. It can suppress more reliably that a 1st gearwheel deform | transforms.

  According to the technique disclosed in this specification, a highly accurate compound gear can be manufactured.

The front view of the compound gear of Example 1 is shown. The external appearance of the 1st gearwheel in which the groove | channel was formed in the hub is shown. Sectional drawing of the gear blank for manufacturing a 1st gearwheel is shown. Sectional drawing of the 1st gearwheel of FIG. 2 is shown. Sectional drawing for demonstrating the process of fixing a 2nd gearwheel to a 1st gearwheel is shown. The perspective view of an upper metallic mold (1) is shown. The top view of an upper metal mold | die (1) is shown. Sectional drawing of an upper metal mold | die (1) is shown. FIG. 6 shows an enlarged view of a range surrounded by a broken line IX in FIG. 5. The figure for demonstrating a spot part is shown. The figure for demonstrating a spot part is shown. The perspective view of an upper metallic mold (2) is shown. The top view of an upper metal mold | die (2) is shown. Sectional drawing of an upper metal mold | die (2) is shown. The perspective view of an upper metal mold | die (3) is shown. The top view of an upper metal mold | die (3) is shown. Sectional drawing of an upper metal mold | die (3) is shown. The perspective view of an upper metallic mold (4) is shown. The top view of an upper metal mold | die (4) is shown. Sectional drawing of an upper metal mold | die (4) is shown. Sectional drawing for demonstrating the manufacturing process of Example 2 is shown. FIG. 22 shows an enlarged view of a range surrounded by a broken line XXII in FIG. 21. The figure for demonstrating a spot part is shown. The external appearance of the 1st gear when a compound gear is manufactured with the conventional manufacturing method is shown. The cross section of the 1st gearwheel manufactured with the conventional manufacturing method is shown.

Before describing the embodiments, some of the technical features of each embodiment are briefly described below. The main technical features are included in the description of each embodiment.
(Feature 1) In the groove forming step, a plurality of grooves extending in the axial direction of the first gear are formed at equal pitches in the circumferential direction on the peripheral surface of the hub of the first gear.
(Feature 2) In the fitting step, the second gear is fitted to the hub of the first gear so that the inner peripheral surface of the second gear faces a groove formed in the hub of the first gear.
(Feature 3) In the loading process, a load is locally applied to the spot portion of the second gear facing the groove of the first gear at the same pitch as the pitch of the groove.
(Characteristic 4) The gear blank for manufacturing the first gear has a thick portion where outer teeth and grooves are formed, and a thin portion.

  FIG. 1 shows a front view of the compound gear 100. The compound gear 100 is a two-stage gear including the first gear 4 and the second gear 2. The second gear 2 has a center hole and is fixed to the hub 6 of the first gear 4 coaxially with the axis 10 of the first gear 4. That is, the compound gear 100 is manufactured by combining the separate first gear 4 and second gear 2.

  FIG. 2 shows a front view of the first gear 4 before the second gear 2 is fixed. As shown in FIG. 2, the first gear 4 includes a tooth portion 8 on which external teeth are formed and a hub 6 having a smaller diameter than the tooth portion 8. The hub 6 has a large diameter portion 6b in which a groove is formed and a small diameter portion 6a in which no groove is formed. The grooves are formed at equal intervals in the circumferential direction of the hub 6 along the axis 10. The groove is aligned with the tooth groove of the tooth portion 8. In the following description, the small diameter portion 6a may be referred to as a shaft portion, and the large diameter portion 6b may be referred to as a groove portion.

  First, a method for manufacturing the first gear 4 will be described. As shown in FIG. 3, a cylindrical gear blank 1 having a thick part 18 and a thin part 12 is prepared. Thereafter, an external tooth 8 a having a tooth groove extending along the direction of the axis 10 is formed in the thick portion 18 using a gear cutting tool (not shown). In addition, the tooth | gear part 8 is formed in the position of the code | symbol 16 among the thick parts 18 of FIG. 3, and the groove part 6b is formed in the position of the code | symbol 14 (refer also FIG. 2). Next, as shown in FIG. 4, the position of the reference numeral 14 of the thick portion 18 is cut in the circumferential direction to form the groove 6b. As a result, the hub 6 is completed with a large-diameter portion 6b in which grooves are formed and a small-diameter portion 6a in which grooves are not formed. 4 corresponds to the cross-sectional view of FIG. 3 to 4 can also be referred to as a step (first gear forming step) in which the tooth portion 8 is defined by cutting the tooth tip at the position of the reference numeral 14 in the external teeth 8a. Thereby, the 1st gearwheel 4 of FIG. 2 can be manufactured.

  Alternatively, the outer teeth 8a may be formed at the position of the reference numeral 16 and the groove may be formed at the position of the reference numeral 14 after the position of the reference numeral 14 of the thick portion 18 is cut in the circumferential direction. In either case, the tooth groove of the tooth portion 8 and the groove of the groove portion 6b can be formed in one step. As described above, in the process of manufacturing the first gear 4 from the gear blank 1, the step of forming grooves in the hub 6 of the first gear 4 (groove forming step) is completed. Since the gear blank 1 has the thick part 18 and the thin part 12, a groove | channel is not formed in the shaft part 6a.

  Next, a method for fixing the second gear 2 to the first gear 4 will be described. FIG. 5 shows a view in which the first gear 4 is fixed to the molds 22 and 24. A mold (also referred to as a lower mold) 22 has a ring shape, and internal teeth are formed on a part of the inner peripheral surface 22h. The internal teeth of the lower mold 22 mesh with the tooth portion 8 of the first gear. The lower mold 22 can prevent the first gear 4 from rotating in the circumferential direction. As will be described later, the lower mold 22 has a plurality of protrusions, and the protrusions are in contact with the second gear 2. The mold 24 (also referred to as a receiving mold) has a ring shape and is in contact with the inner peripheral surface 22 h of the lower mold 22. With the receiving mold 24, the meshing position of the tooth portion 8 of the first gear 4 and the inner teeth of the lower mold 22 can be adjusted. A core rod (mandrel) 26 is inserted into the inner peripheral surface 4 h of the first gear 4. With the first gear 4 fixed to the molds 22 and 24, the second gear 2 is fitted into the groove 6b of the first gear 4 (fitting process). Reference numeral 40 indicates a groove formed in the groove 6b. In the portion where the groove 40 is formed, the inner peripheral surface 2h of the second gear 2 and the groove 6b are not in contact with each other. On the other hand, in the portion where the groove 40 is not formed, the inner peripheral surface 2h of the second gear 2 and the groove portion 6b are in contact with each other. Reference numeral 20 denotes a punch (also referred to as an upper mold). The second gear 2 is disposed between the upper mold 20 and the lower mold 22. In FIG. 5, the portion surrounded by a broken line, that is, the portion indicated by reference numeral IX will be described later.

  Here, the upper mold 20 will be described. FIG. 6 is a perspective view of the upper mold 20. As shown in FIG. 6, the upper mold 20 is provided with a plurality of protrusions 20a. The protrusion 20 a is provided on the end surface in the axial direction of the annular upper mold 20. FIG. 7 shows a plan view of the upper mold 20. As shown in FIG. 7, the protrusions 20 a are formed at equal intervals in the circumferential direction of the upper mold 20. FIG. 8 shows a cross-sectional view along the line VIII-VIII in FIG. As shown in FIGS. 7 and 8, the upper mold 20 has a hemispherical protrusion 20 a formed only on one surface (front surface or back surface) of the upper mold 20.

  FIG. 9 shows an enlarged view of a range surrounded by a broken line IX in FIG. As shown in FIG. 9, the thickness H1 of the second gear 2 on the inner peripheral surface side 2a is thicker than the thickness H2 on the outer peripheral side 2b radially outside the inner peripheral surface side 2a. Further, a protrusion 22 a is formed on the lower mold 22. The protrusion 22a of the lower mold 22 and the protrusion 20a of the upper mold 20 are aligned in the axial direction when both the molds 22 and 20 are combined. In other words, the inner peripheral surface side 2 a of the second gear 2 is sandwiched between the protrusion 22 a of the lower mold 22 and the protrusion 20 a of the upper mold 20. A portion sandwiched between the protrusion 22a of the lower mold 22 and the protrusion 20a of the upper mold 20 corresponds to a spot portion. A plurality of protrusions 22 a are formed at equal intervals in the circumferential direction of the lower mold 22. The pitch at which the protrusions 22a are formed is equal to the pitch at which the protrusions 20a of the upper mold 20 are formed.

  The description of the process of fixing the second gear 2 will be continued. As shown in FIG. 5, with the second gear 2 sandwiched between the upper mold 20 and the mold 22, a load is applied to the upper mold 20, and the inner peripheral surface 2 h of the second gear 2 is plasticized in the groove 40. Let it flow. As described above, the protrusions 20a and the protrusions 22a are formed at equal intervals in the circumferential direction. Therefore, a load is applied discontinuously on the inner peripheral surface side of the second gear 2 in the circumferential direction. That is, a load is applied only to the spot portion of the second gear 2, and no load is applied between the spot portions arranged in the circumferential direction.

  FIG. 10 shows a position (spot portion) 42 where a load is applied from the upper mold 20 to the second gear 2. Each spot portion 42 faces the groove 40 formed in the groove 6b. Therefore, a large load is applied to the spot portion 42 facing the groove 40 in the inner peripheral surface 2 h of the second gear 2, and the load is not applied much to the portion not facing the groove 40. Therefore, when the inner peripheral surface 2h of the second gear 2 plastically flows into the groove 40, the force applied from the second gear 2 to the first gear 4 can be reduced. As a result, the first gear 4 can be prevented from being deformed. Further, since the load applied to the upper mold 20 is concentrated on the spot portion 42, the inner peripheral surface 2h of the second gear 2 can be plastically flowed into the groove 40 with a small load.

  FIG. 11 shows a position (spot portion) 44 where a load is applied from the lower mold 22 to the second gear 2. The spot portion 44 corresponds to the back surface of the spot portion 42 in FIG. As shown in FIG. 11, the spot portion 44 is located between the external teeth of the tooth portion 8 and the external teeth (that is, in the tooth gap). That is, in the loading process, when the first gear 4 is observed in the direction of the axis 10, a load is applied to the spot portion 44 (42) that overlaps the tooth groove of the first gear 4. As described above, a load is applied to the second gear 2 at equal intervals in the circumferential direction. Thereby, plastic deformation of the second gear 2 occurs in a balanced manner in the circumferential direction. Therefore, it is possible to prevent the first gear and / or the second gear from being deformed and causing rotational vibration in the compound gear 100. That is, the highly accurate composite gear 100 can be manufactured.

  Through the above steps, the second gear 2 is fixed to the first gear 4, and the compound gear 100 (see FIG. 1) is completed. The manufacturing method of the present embodiment is particularly suitable for manufacturing the compound gear 100 in which the first gear 4 is formed with a center hole along the axis 10. As described above, the core rod 26 is inserted into the inner peripheral surface 4 h of the first gear 4 when a load is applied to the second gear 2. Therefore, while the core rod 26 is inserted, even if an excessive force is applied from the second gear 2 to the first gear 4, the deformation of the first gear 4 is suppressed. However, when an excessive force is applied from the second gear 2 to the first gear 4, the first gear 4 is deformed after the core rod 26 is removed. Therefore, when a center hole is formed in the first gear 4, the force applied from the second gear 2 to the first gear must be suppressed.

  Here, a conventional manufacturing method will be described with reference to FIGS. FIG. 24 shows the first gear 504 after applying a load uniformly over the conventional manufacturing method, that is, the circumferential direction on the inner peripheral surface side of the second gear (not shown). Except for applying a load uniformly over the circumferential direction of the second gear, it is equal to the manufacturing method of the present embodiment. As shown in FIG. 24, according to the conventional manufacturing method, an excessive force is applied to the first gear 504, and the first gear 504 is deformed. As a result, the roundness of the first gear 504 and the second gear is shifted, or the axis 10 of the first gear 504 and the axis of the second gear are shifted. FIG. 25 corresponds to the cross-sectional view of FIG. As shown in FIG. 25, in the conventional manufacturing method, the deformation of the groove portion 506b is more remarkable than the deformation of the tooth portion 508. The groove 506b hardly deforms while the core rod 26 (see FIG. 5) is inserted. That is, the deformation of the first gear 504 is not significant at the stage where the second gear is fixed to the groove 506b. However, when the core rod 26 is removed, the first gear 504 is deformed, and the second gear is also deformed as the first gear 504 is deformed. Therefore, the conventional manufacturing method cannot manufacture a highly accurate compound gear.

  12 to 14 show the upper mold 220. FIG. The upper mold 220 is a modification of the upper mold 20. 12 is a perspective view of the upper mold 220, FIG. 13 is a plan view of the upper mold 220, and FIG. 14 is a cross-sectional view taken along line XIV-XIV in FIG. As shown in FIGS. 12 and 14, the thickness of the upper mold 220 on the front surface side is thinner than the thickness on the back surface side, and a protrusion 220 a is formed on the end surface on the front surface side. The protrusions 220 a are formed at the same pitch as the protrusions 20 a of the mold 20. Therefore, in order to fix the second gear 2 to the first gear 4, the upper mold 220 can be used instead of the upper mold 20. The protrusion 220a can be easily formed by cutting the surface of the mold 220 at a predetermined pitch. Therefore, it can be manufactured at a lower cost than the upper mold 20.

  An upper mold 320 is shown in FIGS. The upper mold 320 is a modification of the upper mold 220. 15 is a perspective view of the upper mold 320, FIG. 16 is a plan view of the upper mold 320, and FIG. 17 is a cross-sectional view taken along line XVII-XVII in FIG. The surface of the upper mold 320 is processed into a wave shape. As a result, a protrusion 320 a is formed on the surface of the upper mold 320. The protrusions 320a are formed at the same pitch as the protrusions 220a of the upper mold 220. The upper mold 320 can be manufactured at a lower cost than the upper mold 220.

  18 to 20 show the upper mold 420. 18 is a perspective view of the upper mold 420, FIG. 19 is a plan view of the upper mold 420, and FIG. 20 is a cross-sectional view taken along line XX-XX in FIG. As shown in FIGS. 18 and 20, no protrusion is formed on either the front surface or the back surface of the upper mold 420. As shown in FIG. 19, a protrusion 420 a is formed on the inner peripheral surface of the upper mold 420. In other words, the inner teeth 420 a are formed on the inner peripheral surface of the upper mold 420. The pitch of the inner teeth 420 a is equal to the pitch of the protrusions 20 a of the upper mold 20. Hereinafter, a method for manufacturing the composite gear 100 using the upper mold 420 will be described.

  FIG. 21 is a diagram for explaining the manufacturing process of this embodiment. FIG. 21 is substantially the same as FIG. 4 of the first embodiment. Therefore, the description which overlaps with Example 1 is abbreviate | omitted. In the present embodiment, the shape of the second gear 402 is different from the shape of the second gear 2. Differences between the second gear 402 and the second gear 2 will be described later.

  FIG. 22 shows an enlarged view of a range surrounded by a broken line XXII in FIG. As shown in FIG. 22, the thickness H11 of the second gear 402 on the inner peripheral surface side 402a is thicker than the thickness H12 on the outer peripheral side 402b on the radially outer side than the inner peripheral surface side 402a. The protrusion 420a of the upper mold 420 is in contact with the inner peripheral surface side 402a and is not in contact with the outer peripheral side 402b. Therefore, when a load is applied to the upper mold 420, the load is applied only to a portion of the inner peripheral surface 402a that is in contact with the protrusion 420a. FIG. 23 shows a spot portion 442 where a load is applied from the upper mold 420 to the second gear 402. Also in the manufacturing method of the present embodiment, a load is applied discontinuously on the inner peripheral surface side of the second gear 402 in the circumferential direction. As shown in FIG. 23, each spot portion 442 faces the groove 40 formed in the groove 6b. Therefore, even in the manufacturing method of the present embodiment, the first gear 4 and the second gear 402 can be fixed using the plastic flow technique without applying excessive force to the first gear 4.

  In the above embodiment, the example in which the step of forming the tooth portion on the first gear (first gear forming step) and the step of forming the groove on the hub of the first gear (groove forming step) have been described. However, the first gear forming step and the groove forming step may be performed separately. The pitch of the grooves formed in the hub of the first gear can be made different from the pitch of the external teeth of the first gear.

  In the above embodiment, the first gear is a spur gear, and the groove formed in the first gear (the groove in which the second gear plastically flows) extends in the same direction as the tooth groove of the first gear. Therefore, the groove formed in the first gear extends parallel to the axis of the first gear. However, the first gear may not be a spur gear. For example, the first gear may be a helical gear (tilted gear). Further, the groove formed in the first gear may not be parallel to the axis of the first gear. The groove formed in the first gear may be substantially along the axial direction of the first gear.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2: Second gear 2h: Center hole 4 of second gear 4: First gear 6: Hub 40 of first gear: Groove 42 formed on peripheral surface of hub: Spot portion 100: Compound gear

Claims (2)

A method of manufacturing a compound gear in which a second gear is coaxially fixed to a hub of a first gear,
Forming a groove extending along the axial direction of the first gear on the peripheral surface of the hub; and
A fitting step of fitting a second gear having a center hole to the hub;
A load step of locally applying an axial load to the spot portion of the second gear facing the groove until the periphery of the center hole of the second gear plastically flows into the groove;
Equipped with a,
In the groove forming process, the groove of the hub and the tooth groove of the first gear are formed in a straight line in the axial direction in one process,
A load step, when observing the first gear in the axial direction, a manufacturing method of a composite gear, characterized that you apply a load to the spot portion of the tooth groove overlap of the first gear.   The manufacturing method according to claim 1, wherein the thickness of the second gear in the spot portion is thicker than the thickness of the radially outer portion of the spot portion.

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