JP2017202565A - Process of manufacture of gear transmission - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gear transmission in which a looseness or noise occurred at a fitting hole between a fitted part of a crank shaft and a transmission gear can be restricted at a low cost.SOLUTION: A gear transmission 1 comprises a crank shaft 10 having a fitted part 10c; gear members 14, 16 having teeth 14a and 16a; a first cylinder 2 having teeth 3 engaged with teeth 14a, 16a of the gear members 14, 16; a second cylinder 4 that can be relatively rotated in respect to the first cylinder 2 through oscillation of the gear members 14, 16 accompanied with rotation of the crank shaft 10; and a transmission gear 20 having a fitting hole 20b to which the fitted part 10c of the crank shaft 10 is fitted. The fitting hole 20b of the transmission gear 20 shows that a shape of section crossing at a right angle in an axial direction of the crank shaft 10 is polygon, and the fitted part 10c of the crank shaft 10 shows that a shape of section crossing at a right angle in an axial direction of the crank shaft 10 is polygon adapted to a sectional shape of the fitted hole 20b.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for manufacturing a gear transmission.

  Conventionally, there has been known an eccentric oscillating gear transmission that relatively rotates an outer cylinder and a carrier by oscillating and rotating an external gear in conjunction with rotation of an eccentric body provided on a crankshaft. Yes. In such a gear transmission, a transmission gear (spar gear) is attached to the fitting portion of the crankshaft. This transmission gear plays a role of rotating the crankshaft in response to the rotation of the input shaft.

  In general, a spline connection using an involute spline is employed for the connection between the crankshaft and the transmission gear (see, for example, Patent Documents 1 and 2). Specifically, in this spline coupling, for example, as shown in FIG. 9, teeth 112 formed on the outer peripheral surface of the fitting portion 111 of the crankshaft by spline processing and the inner peripheral surface of the fitting hole 121 of the transmission gear 120. The teeth 122 formed on the mating parts are fitted.

  By the way, when the gear transmission is used, a large external force is applied to the crankshaft and the transmission gear. In order to give the crankshaft and the transmission gear with strength that can withstand this external force, the crankshaft and the transmission gear are subjected to heat treatment (quenching) after spline processing.

JP 2010-286098 A JP-A-10-252638

  However, due to deformation during heat treatment, variations occur in the outer diameter of the fitting portion of the crankshaft and the inner diameter of the fitting hole of the transmission gear. For this reason, it is necessary to design the gap between the fitting portion and the fitting hole to be large, including variations in the outer diameter of the fitting portion and the inner diameter of the fitting hole due to deformation during heat treatment. As a result, when there is a large dimensional variation due to deformation during heat treatment, rattling may occur in the mating portion and the mating hole that are mated with each other, and noise due to this rattling may occur.

  In order to suppress such rattling and noise, it is possible to reduce the dimensional variation caused by the heat treatment by finishing the fitting portion and the fitting hole after the heat treatment. However, in the case of spline connection using involute splines, finishing with a hard hob is necessary to finish the fitting part of the crankshaft, and hard broaching is required to finish the fitting hole of the transmission gear. Finishing is required. Both finishing processes require expensive dedicated tools and expensive additional equipment, leading to increased costs.

  The present invention has been made to solve the above-described problems, and its object is to suppress rattling and noise in the fitting hole between the fitting portion of the crankshaft and the transmission gear at a low cost. It is to provide a method of manufacturing a gear transmission that can achieve this.

  The manufacturing method of the gear transmission according to the present invention includes a crankshaft having an eccentric portion and a fitting portion, a gear member having a through hole into which the eccentric portion is inserted and having a tooth portion, and the teeth of the gear member. A first cylindrical portion having a tooth portion meshing with the portion, and the crankshaft being rotatably supported, and being rotatable relative to the first cylindrical portion by swinging of the gear member accompanying the rotation of the crankshaft. And a transmission gear having a fitting hole into which the fitting portion of the crankshaft is fitted and for rotating the crankshaft about the axis. The fitting hole of the transmission gear has a polygonal cross-sectional shape when cut along a plane perpendicular to the axial direction of the crankshaft, and the fitting portion of the crankshaft is in the axial direction of the crankshaft. The cross-sectional shape when cut along a plane orthogonal to the polygonal shape is a polygon that matches the cross-sectional shape of the fitting hole, and the fitting hole of the transmission gear and the fitting portion of the crankshaft are distorted by heat treatment. The gear transmission device is manufactured to have a polygonal shape that can be suppressed, and finish processing is performed, and the fitting portion of the crankshaft and the cylindrical portion are formed at the time of processing. A method of manufacturing a gear transmission, in which a center position is concentric and processed.

  In this configuration, the shape of the cross section of the fitting hole in the transmission gear is a polygon, and the shape of the cross section of the fitting portion in the crankshaft is a polygon that matches the cross sectional shape of the fitting hole. Thereby, the finishing process of the fitting hole and fitting part after heat processing can be performed at low cost. Specifically, since the cross-sectional shape of the fitting portion of the crankshaft is a polygon, it can be finished using, for example, a cam grinder after the heat treatment. Therefore, expensive dedicated tools and expensive additional equipment are unnecessary. In addition, the fitting hole of the transmission gear will be finished with a hard broach after heat treatment, but since the cross-sectional shape is polygonal, it is easier to manufacture a dedicated tool than the conventional involute spline shape. . Therefore, finishing can be performed at a lower cost than in the past.

  From the above, according to the present invention, in the finishing process of the fitting hole and the fitting portion, an expensive dedicated tool and expensive additional equipment are not required, so that the fitting portion of the crankshaft and the transmission gear are fitted. It becomes possible to suppress rattling and noise in the hole at low cost.

  In the manufacturing method of the gear transmission, the processing is preferably performed after heat treatment.

  In the method for manufacturing the gear transmission, it is preferable that the fitting portion of the crankshaft and the cylindrical portion are processed with the same tool.

  As described above, according to the gear transmission of the present invention, rattling and noise in the fitting hole between the fitting portion of the crankshaft and the transmission gear can be suppressed at a low cost.

It is sectional drawing which shows the gear transmission which concerns on one Embodiment of this invention. It is the II-II sectional view taken on the line in FIG. It is a top view which shows the said gear transmission. It is a perspective view which shows the fitting structure of the crankshaft and transmission gear in the said gear transmission. It is the VV sectional view taken on the line in FIG. It is a top view which shows the modification 1 of the said gear transmission. It is sectional drawing of the principal part in the gear transmission of the modification 1. It is sectional drawing which shows the modification 2 of the said gear transmission. It is sectional drawing which shows the crankshaft and transmission gear in the conventional gear transmission.

  Hereinafter, the gear transmission 1 which concerns on one Embodiment of this invention is demonstrated in detail with reference to drawings. The gear transmission 1 is applied as a speed reducer to, for example, a revolving part such as a revolving drum or arm joint of a robot, or a revolving part of various machine tools.

<Overall structure of gear transmission>
The gear transmission 1 according to the present embodiment swings and rotates the first external gear 14 in conjunction with the first eccentric portion 10a of the crankshaft 10 and is coupled with the second eccentric portion 10b of the crankshaft 10. The output rotation decelerated from the input rotation is obtained by swinging and rotating the two external gears 16.

  As shown in FIG. 1, the gear transmission 1 includes an outer cylinder 2 as a first cylinder part, a carrier 4 as a second cylinder part, an input shaft 8, and a plurality of (for example, three) crankshafts 10. The first external gear 14 and the second external gear 16 as gear members and a plurality of (for example, three) transmission gears 20 are provided.

  As shown in FIG. 2, the outer cylinder 2 constitutes the outer surface of the gear transmission 1 and has a substantially cylindrical shape. A large number of pin grooves 2 b are formed on the inner peripheral surface of the outer cylinder 2. Each pin groove 2b extends in the axial direction of the outer cylinder 2, and has a semicircular cross-sectional shape in a cross section orthogonal to the axial direction. These pin grooves 2 b are arranged on the inner peripheral surface of the outer cylinder 2 at equal intervals in the circumferential direction. An internal tooth pin 3 is fitted in each pin groove 2b. That is, the outer cylinder 2 has a large number of internal tooth pins 3 as tooth portions.

  Each internal tooth pin 3 has a cylindrical shape, and is arranged in a posture extending in the axial direction of the outer cylinder 2 in the corresponding pin groove 2b. In the pin groove 2b, each internal tooth pin 3 can rotate around its axis. The first external gear 14 and the second external gear 16 mesh with these internal teeth pins 3.

  As shown in FIG. 1, the carrier 4 is accommodated in the outer cylinder 2 in a state of being arranged coaxially with the outer cylinder 2. The carrier 4 rotates relative to the outer cylinder 2 around the same axis. Specifically, the carrier 4 is supported so as to be rotatable relative to the outer cylinder 2 by a pair of carrier bearings 6 that are provided apart from each other in the axial direction. The carrier 4 includes a base portion 4a, an end plate portion 4b, and a plurality of (for example, three) shaft portions 4c.

  The base portion 4 a is disposed in the vicinity of one end portion in the axial direction in the outer cylinder 2. A circular through hole 4d is provided in the central portion of the base portion 4a in the radial direction. Around the through hole 4d, a plurality of (for example, three) crankshaft mounting holes 4e (hereinafter simply referred to as mounting holes 4e) are provided at equal intervals in the circumferential direction.

  The end plate portion 4b is provided to be spaced apart from the base portion 4a in the axial direction, and is disposed in the vicinity of the other end portion in the axial direction in the outer cylinder 2. A through hole 4f is provided at the radial center of the end plate portion 4b. Around the through hole 4f, a plurality of (for example, three) crankshaft mounting holes 4g (hereinafter simply referred to as mounting holes 4g) are provided at positions corresponding to the plurality of mounting holes 4e of the base portion 4a. A closed space surrounded by both inner surfaces of the end plate portion 4 b and the base portion 4 a facing each other and the inner peripheral surface of the outer cylinder 2 is formed in the outer cylinder 2.

  The three shaft portions 4c are integrally provided on the base portion 4a and linearly extend from the base portion 4a to the end plate portion 4b side. The three shaft portions 4c are arranged at equal intervals in the circumferential direction (see FIG. 2). Each shaft portion 4c is fastened to the end plate portion 4b by a bolt 4h (see FIG. 1). Thereby, the base part 4a, the shaft part 4c, and the end plate part 4b are integrated.

  The input shaft 8 functions as an input unit to which rotation is input by a drive motor (not shown). The input shaft 8 is inserted into the through hole 4f of the end plate portion 4b and the through hole 4d of the base portion 4a. The input shaft 8 is arranged such that its axis coincides with the axes of the outer cylinder 2 and the carrier 4 and rotates around its axis. An input gear 8 a is provided on the outer peripheral surface of the distal end portion of the input shaft 8.

  The three crankshafts 10 are arranged at equal intervals around the input shaft 8 in the outer cylinder 2 (see FIG. 2). Each crankshaft 10 is attached to the corresponding attachment hole 4e of the base portion 4a and the attachment hole 4g of the end plate portion 4b (see FIG. 1). Specifically, the axially inner portion of each crankshaft 10 by a predetermined length from one axial end is mounted in the mounting hole 4e of the base portion 4a via the first crank bearing 12a. On the other hand, the other axial end portion of each crankshaft 10 is mounted in the mounting hole 4g of the end plate portion 4b via the second crank bearing 12b. Each crankshaft 10 is supported by both crank bearings 12a and 12b so as to be rotatable about the axis with respect to the carrier 4. In FIG. 1, hatching (hatched lines) indicating a cross section of the crankshaft 10 is omitted.

  Each crankshaft 10 has an eccentric part. The eccentric portion includes a first eccentric portion 10a and a second eccentric portion 10b that are arranged in the axial direction between portions supported by the crank bearings 12a and 12b. Each of the first eccentric portion 10a and the second eccentric portion 10b has a cylindrical shape. The first eccentric portion 10a and the second eccentric portion 10b are each eccentric from the axis of the crankshaft 10 by a predetermined amount of eccentricity, and are arranged so as to have a phase difference of a predetermined angle. A fitting portion 10c to which the transmission gear 20 is attached is provided at one end portion of the crankshaft 10, that is, a portion on the axially outer side of a portion attached in the attachment hole 4e of the base portion 4a. Details of the fitting portion 10c will be described later.

  As shown in FIGS. 1 and 2, the first external gear 14 is disposed in the closed space in the outer cylinder 2, and the first roller bearing 18 a is disposed on the first eccentric portion 10 a of each crankshaft 10. Is attached through. When each crankshaft 10 rotates and the first eccentric portion 10a rotates eccentrically, the first external gear 14 swings and rotates while meshing with the internal pin 3 in conjunction with the eccentric rotation.

  The first external gear 14 has a size slightly smaller than the inner diameter of the outer cylinder 2. The first external gear 14 includes a first external tooth 14a, a central through hole 14b, a plurality of (for example, three) first eccentric portion insertion holes 14c, and a plurality of (for example, three) shaft portion insertion holes 14d. And have.

  As shown in FIG. 2, the first external teeth 14 a are provided on the outer peripheral surface of the first external gear 14. The tooth surface of the first external tooth 14a has a wave shape that is smoothly continuous over the entire circumferential direction in a cross section orthogonal to the axial direction. In other words, the tooth surfaces of the first external teeth 14a are alternately arranged along the circumferential direction with crests located on the radially outer side and troughs located on the radially inner side. The tip (peak) of the peak portion of the first external tooth 14 a has a protruding amount outward in the radial direction so that contact with the internal tooth pin 3 is suppressed during the swing rotation of the first external gear 14. It is preferably adjusted. The same applies to the tip of the peak portion of the second external tooth 16a.

  The number of teeth of the first external teeth 14 a is set slightly smaller than the number of internal tooth pins 3. In the present embodiment, the number of teeth of the first external teeth 14 a is set to be one less than the number of internal tooth pins 3.

  The central through hole 14 b is provided in the central portion in the radial direction of the first external gear 14. The input shaft 8 is inserted into the central through hole 14b with play.

  The three first eccentric portion insertion holes 14 c are provided at equal intervals in the circumferential direction around the central portion through hole 14 b in the first external gear 14. The first eccentric portions 10a of the respective crankshafts 10 are inserted into the first eccentric portion insertion holes 14c with the first roller bearings 18a interposed therebetween.

  The three shaft portion insertion holes 14 d are provided at equal intervals in the circumferential direction around the central portion through hole 14 b in the first external gear 14. Each shaft portion insertion hole 14d is disposed at a position between the three first eccentric portion insertion holes 14c in the circumferential direction. The corresponding shaft portion 4c is inserted into each shaft portion insertion hole 14d with play.

  The second external gear 16 is disposed in the closed space in the outer cylinder 2 and is attached to the second eccentric portion 10b of each crankshaft 10 via a second roller bearing 18b. The first external gear 14 and the second external gear 16 are provided side by side in the axial direction corresponding to the arrangement of the first eccentric portion 10a and the second eccentric portion 10b. When each crankshaft 10 rotates and the second eccentric portion 10b rotates eccentrically, the second external gear 16 rotates and rotates while meshing with the internal tooth pin 3 in conjunction with the eccentric rotation.

  The second external gear 16 has a size slightly smaller than the inner diameter of the outer cylinder 2. The second external gear 16 includes second external teeth 16a, a central through hole 16b, a plurality (for example, three) of second eccentric portion insertion holes 16c, and a plurality of (for example, three) shaft portion insertion holes 16d. ing. These have the same structure as the first external teeth 14a, the central through hole 14b, the plurality of first eccentric portion insertion holes 14c, and the plurality of shaft portion insertion holes 14d of the first external gear 14. The second eccentric portion 10b of the crankshaft 10 is inserted into each second eccentric portion insertion hole 16c with the second roller bearing 18b interposed therebetween.

  Each transmission gear 20 transmits the rotation of the input gear 8a to the corresponding crankshaft 10. Each transmission gear 20 is externally fitted to a fitting portion 10 c provided at one end of the corresponding crankshaft 10. Specifically, each transmission gear 20 has a fitting hole 20b into which the fitting portion 10c of the crankshaft 10 is fitted. The fitting hole 20b is a through hole provided at substantially the center (substantially the middle in the radial direction) of the transmission gear 20. Each transmission gear 20 rotates integrally with the crankshaft 10 about the same axis as the rotation axis of the crankshaft 10. Each transmission gear 20 has external teeth 20a that mesh with the input gear 8a.

<Fitting structure of crankshaft and transmission gear>
Hereinafter, the fitting structure between the crankshaft 10 and the transmission gear 20 will be described. FIG. 3 is a plan view showing the gear transmission 1, and FIG. 4 is a perspective view showing a fitting structure between the crankshaft 10 and the transmission gear 20 in the gear transmission 1. 5 is a cross-sectional view taken along line VV in FIG. FIG. 5 shows a cross section when the crankshaft 10 and the transmission gear 20 are cut along a plane perpendicular to the axial direction of the crankshaft 10.

  As shown in FIGS. 3 to 5, the fitting hole 20 b of the transmission gear 20 has a polygonal cross-sectional shape when cut along a plane orthogonal to the axial direction of the crankshaft 10. Moreover, the fitting part 10c of the crankshaft 10 is a polygon in which the cross-sectional shape when cut along a plane orthogonal to the axial direction of the crankshaft 10 matches the cross-sectional shape of the fitting hole 20b.

  The cross-sectional shape of the fitting hole 20b is preferably a regular polygon. And it is preferable that the cross-sectional shape of the fitting part 10c is a regular polygon which fits the cross-sectional shape of the fitting hole 20b. The number of regular polygon sides in the fitting hole 20b and the fitting portion 10c is more preferably an even number of 4 or more. In the present embodiment, the cross-sectional shape of the fitting hole 20b and the cross-sectional shape of the fitting portion 10c are regular hexagons.

  As shown in FIG. 4, the fitting portion 10c of the crankshaft 10 has a hexagonal column shape extending in the axial direction from a substantially cylindrical columnar portion 10f supported by the first crank bearing 12a in the crankshaft 10. Yes. That is, the fitting portion 10 c has six planes parallel to the axial direction of the crankshaft 10.

  The transmission gear 20 has a recess 20c positioned on the outer side in the axial direction than the fitting hole 20b. The recess 20c is a portion that is recessed in the axial direction from the outer surface 20d of the transmission gear 20. The inner peripheral surface of the fitting hole 20b is located on the radially inner side with respect to the inner peripheral surface of the recess 20c. The fitting portion 10c protrudes outward in the axial direction from the fitting hole 20b. That is, the end surface 10d of the fitting portion 10c is located on the outer side in the axial direction than the fitting hole 20b.

  As shown in FIGS. 1 and 4, the crankshaft 10 is provided with a first retaining ring 31 and a second retaining ring 32. The first retaining ring 31 and the second retaining ring 32 are fixed to the crankshaft 10. The first retaining ring 31 and the second retaining ring 32 each have a ring shape. The first retaining ring 31 is disposed on the inner side in the axial direction than the transmission gear 20. The second retaining ring 32 is positioned on the outer side in the axial direction than the transmission gear 20 and is disposed in the recess 20c. These retaining rings 31 and 32 position the transmission gear 20 with respect to the crankshaft 10 by sandwiching the transmission gear 20 from both sides in the axial direction. In FIG. 4, illustration of the first retaining ring 31 and the second retaining ring 32 is omitted, and positions where these are provided are indicated by two-dot chain lines 31 and 32, respectively.

  As shown in FIG. 5, each of the plurality of corners (polygonal corners) 10e in the cross section of the fitting portion 10c has an arc shape. Each of the plurality of corner portions 20e in the cross section of the fitting hole 20b has an arc shape. That is, each corner portion 10e between the adjacent planes of the fitting portion 10c is chamfered so as to be a curved surface convex outward. Further, each corner 20e of the fitting hole 20b is chamfered so as to be a concave curved surface facing the curved surface constituting the corner 10e of the corresponding fitting 10c. The radius of curvature of the corner 10e in the fitting portion 10c and the radius of curvature of the corner 20e in the fitting hole 20b are not particularly limited, but are preferably about 3 to 5 mm. Moreover, it is more preferable that the radius of curvature of the corner portion 10e in the fitting portion 10c is designed to be larger than the radius of curvature of the corner portion 20e in the fitting hole 20b.

<Operation>
Next, the operation of the gear transmission 1 will be described. First, rotation is input to the input shaft 8 of the gear transmission 1 by driving a motor (not shown), for example. As a result, the input gear 8 a rotates together with the input shaft 8. The rotation of the input gear 8 a is transmitted to each crankshaft 10 via each transmission gear 20.

  As each crankshaft 10 rotates, the first eccentric portion 10a and the second eccentric portion 10b of each crankshaft 10 rotate eccentrically. As a result, the first external gear 14 swings and rotates while meshing with the internal pin 3 in conjunction with the eccentric rotation of the first eccentric portion 10a, and the second outer gear interlocks with the eccentric rotation of the second eccentric portion 10b. The toothed gear 16 swings and rotates while meshing with the internal tooth pin 3. The swing rotation of the first external gear 14 and the second external gear 16 is transmitted to the carrier 4 through each crankshaft 10, and the entire carrier 4 is rotated with respect to the outer cylinder 2 at a speed reduced from the input rotation. Relative rotation.

<Modification 1>
FIG. 6 is a plan view showing Modification 1 of the gear transmission 1. FIG. 7 is a cross-sectional view of a main part of the gear transmission 1 shown in FIG. In the first modification, the structure in which the transmission gear 20 is positioned with respect to the crankshaft 10 is different from the above-described embodiment. Specifically, it is as follows.

  In this modification 1, the fitting part 10c of the crankshaft 10 has the same cross-sectional shape as the above-mentioned embodiment shown in FIG. That is, the fitting part 10c has a hexagonal column shape. As shown in FIG. 7, in the crankshaft 10, the columnar portion 10f supported by the first crank bearing 12a has a substantially columnar shape, and has a larger outer diameter than the fitting portion 10c and the fitting hole 20b. Have. Accordingly, a step 10g is formed at the boundary between the cylindrical portion 10f and the fitting portion 10c. The transmission gear 20 is restricted from moving toward one side (inside) in the axial direction by contacting the step 10g.

  Further, the movement of the transmission gear 20 to the other side (outside) in the axial direction is restricted by the bolt 33 and the washer 34. The washer 34 has a larger outer diameter than the fitting hole 20 b, and the inner surface of the washer 34 is in contact with the outer surface 20 d of the transmission gear 20. The bolt 33 is screwed into a screw hole provided in the fitting portion 10c and the cylindrical portion 10f. Thereby, the transmission gear 20 is positioned with respect to the crankshaft 10.

  Therefore, in this modification 1, the 1st retaining ring 31 provided in the crankshaft 10 in the gear transmission 1 shown in FIG.1 and FIG.4 is unnecessary. In FIG. 7, hatching (hatched lines) indicating a cross section of the crankshaft 10 is omitted.

<Modification 2>
FIG. 8 is a cross-sectional view showing a second modification of the gear transmission 1. As shown in FIG. 8, the fitting hole 20 b of the transmission gear 20 has a square shape in cross section when cut along a plane orthogonal to the axial direction of the crankshaft 10. In addition, the fitting portion 10c of the crankshaft 10 is a regular square whose cross-sectional shape when cut along a plane orthogonal to the axial direction of the crankshaft 10 matches the cross-sectional shape of the fitting hole 20b.

  In addition, each of the plurality of corners 10e in the cross section of the fitting portion 10c has an arc shape, and each of the plurality of corners 20e in the cross section of the fitting hole 20b has an arc shape. The curvature radius of the corner portion 10e in the fitting portion 10c is designed to be larger than the curvature radius of the corner portion 20e in the fitting hole 20b.

  As described above, in the present embodiment, the cross-sectional shape of the fitting hole 20b in the transmission gear 20 is a polygon, and the cross-sectional shape of the fitting portion 10c in the crankshaft 10 is the cross-sectional shape of the fitting hole 20b. It is a conforming polygon. Thereby, rattling and noise in the fitting portion 10c of the crankshaft 10 and the fitting hole 20b of the transmission gear 20 are suppressed while finishing the fitting hole 20b and the fitting portion 10c after heat treatment at low cost. It becomes possible to do. Note that the noise generated in the gear transmission 1 is dominated by the tooth contact noise of the meshing portion between the input gear 8a of the input shaft 8 and the external teeth 20a of the transmission gear 20, and the fitting between the crankshaft 10 and the transmission gear 20 is dominant. Shaking that occurs in the joint area has a significant effect. Therefore, the gear transmission 1 according to the present embodiment is effective as a noise reduction measure.

  Further, in the present embodiment in which the fitting hole 20b and the fitting portion 10c are polygonal as compared with the case where the fitting hole and the fitting portion have the involute spline shape shown in FIG. 9, the distortion itself before and after the heat treatment is reduced. Can be suppressed. Therefore, in this embodiment, a certain degree of accuracy can be ensured without the finishing process after the heat treatment, and the rattling can be reduced. In this embodiment, higher dimensional accuracy can be obtained by finishing after heat treatment.

  Further, as described above, the fitting portion 10c of the crankshaft 10 has a polygonal cross-sectional shape, and therefore can be finished using a cam grinder after heat treatment, for example. Moreover, the fitting portion 10c can be processed with the same tool as the cylindrical portion 10f (journal portion). Specifically, the fitting part 10c can make the center position at the time of processing concentric with the cylindrical part 10f. Therefore, the concentricity between the fitting portion 10c and the cylindrical portion 10f can be improved. Thereby, the shake of the crankshaft can be suppressed. Moreover, the process of the fitting part 10c and the cylindrical site | part 10f can be performed by one process, and an additional installation becomes unnecessary.

  Moreover, in this embodiment, since the cross-sectional shape of the fitting hole 20b and the fitting part 10c is a regular polygon, especially the process of the fitting part 10c of the crankshaft 10 becomes easy. Specifically, when the fitting portion 10c of the crankshaft 10 is a regular polygon, the fitting portion 10c is easily machined into a regular polygon using, for example, a processing device capable of polygonal cutting by turning. Can do. Thereby, processing cost can be reduced more.

  In this embodiment, since the number of regular polygon sides in the cross-sectional shapes of the fitting hole 20b and the fitting portion 10c is an even number of 4 or more, each side has opposite sides parallel to each other. Yes. Therefore, when measuring the dimensions of the fitting hole 20b and the fitting portion 10c, it is only necessary to measure the distance between a pair of opposing sides, which facilitates dimension measurement.

  Moreover, in this embodiment, since the some corner | angular part 20e in the fitting hole 20b and the some corner | angular part 10e in the fitting part 10c have a shape chamfered by circular arc shape, stress is applied to each corner | angular part. Can be concentrated. Thereby, durability of each corner | angular part improves.

  Further, in this embodiment, the radius of curvature of the corner portion 10e in the fitting portion 10c is larger than the radius of curvature of the corner portion 20e in the fitting hole 20b, and therefore the fitting portion 10c of the crankshaft 10 is fitted to the transmission gear 20. It becomes easy to insert into the joint hole 20b. Thereby, workability | operativity improves.

  Further, in the gear transmission 1, when the fitting between the fitting hole 20b and the fitting portion 10c is tight-fitting or a gap fitting of 40 μm or less, the vibration of the transmission gear 20 due to rattling is further suppressed. In addition, noise can be further reduced.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to these embodiment, A various change, improvement, etc. are possible in the range which does not deviate from the meaning.

  For example, although the case where the cross-sectional shape of the fitting hole 20b and the fitting part 10c is a regular polygon was illustrated in the said embodiment, the polygon which is not a regular polygon may be sufficient.

  Moreover, although the said embodiment illustrated the case where the number of the sides of the regular polygon in the fitting hole 20b and the fitting part 10c was an even number of 4 or more, the number of sides may be an odd number.

  Moreover, in the said embodiment, although the case where the curvature radius of the corner | angular part 10e in the fitting part 10c was larger than the curvature radius of the corner | angular part 20e in the fitting hole 20b was illustrated, these curvature radii are the same, for example Also good.

  Moreover, in the said embodiment, although the case where the input shaft 8 was provided in the center of radial direction was illustrated, it is not limited to this. The input shaft 8 may be provided at a position shifted in the radial direction from the center.

  In the above embodiment, a case where a plurality of (for example, three) crankshafts are provided is illustrated. However, for example, one crankshaft may be provided at the radial center. In this case, it is also possible to adopt a configuration in which a cylinder is fitted into the through hole 4d, the through hole 4f, the through hole 14b, and the through hole 16b. For example, a cable or the like is disposed in the cylinder.

  Further, either the carrier 4 or the outer cylinder 2 may be fixed. In other words, the carrier 4 may be fixed and the outer cylinder 2 may be rotated relative to the carrier 4. The outer cylinder 2 may be fixed and the carrier 4 may be rotated relative to the outer cylinder 2. Form may be sufficient.

  Moreover, although the case where the fitting part 10c of the crankshaft 10 was provided in the one end part of the crankshaft 10 was illustrated in the said embodiment, it is not limited to this. The fitting portion 10c may be provided, for example, at the other end portion of the crankshaft 10, or may be provided at an intermediate portion between the one end portion and the other end portion.

DESCRIPTION OF SYMBOLS 1 Gear transmission 2 Outer cylinder 3 Internal tooth pin 4 Carrier 10 Crankshaft 10a 1st eccentric part 10b 2nd eccentric part 10c Fitting part 14 1st external gear 16 2nd external gear 20 Transmission gear 20b Fitting hole

Claims (3)

A crankshaft having an eccentric part, a cylindrical part and a fitting part;
A gear member having a through-hole into which the eccentric portion is inserted and having a tooth portion;
A first tube portion having a tooth portion meshing with the tooth portion of the gear member;
A second cylinder part that rotatably supports the crankshaft, and is rotatable relative to the first cylinder part by swinging of the gear member accompanying the rotation of the crankshaft;
Having a fitting hole into which the fitting portion of the crankshaft is fitted, and a transmission gear for rotating the crankshaft around the axis,
The fitting hole of the transmission gear has a polygonal cross-sectional shape when cut along a plane perpendicular to the axial direction of the crankshaft, and the fitting portion of the crankshaft is in the axial direction of the crankshaft. The shape of the cross section when cut in a plane perpendicular to the polygon is a polygon that matches the cross sectional shape of the fitting hole,
In the method for manufacturing a gear transmission, the fitting hole of the transmission gear and the fitting portion of the crankshaft are formed in a polygon that can suppress distortion due to heat treatment, and are subjected to finishing. There,
A method of manufacturing a gear transmission, wherein the fitting portion of the crankshaft and the cylindrical portion are processed with a center position at the time of processing being concentric.   The method of manufacturing a gear transmission according to claim 1, wherein the processing is performed after heat treatment.   The gear transmission device manufacturing method according to claim 2, wherein the fitting portion of the crankshaft and the cylindrical portion are processed with the same tool.

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