Component for reduction gear and heat treatment method thereof

Abstract

The present invention provides a technology that can effectively use heat treatment with high hardness areas and low hardness areas on a workpiece of a speed reducer component. The present invention provides a speed reducer component, which is provided with a high hardness area and a low hardness area whose surface hardness is lower than that of the high hardness area, and the low hardness area is provided within a range where the load applied when the speed reducer is running is smaller than that of the high hardness area.

Description

[0001] This application is a divisional application of the Chinese invention patent application with the application date of December 26, 2017, application number 201711431023.8, and name “Heat treatment method for reduction gear and rotating body”. Technical Field

[0002] The invention relates to a component for a reduction gear and a heat treatment method thereof. Background Art

[0003] An eccentric oscillating type reduction gear transmission is described in Patent Document 1. In this reduction gear transmission, rolling elements are arranged between an eccentric body and an external gear, and the outer peripheral surface of the eccentric body constitutes a rolling surface of the rolling element.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2015-224707

[0005] For a component having a rolling surface of a rolling element such as the eccentric body of Patent Document 1, the rolling surface is required to have a higher hardness in order to achieve an improvement in fatigue strength. For this reason, a heat treatment that increases the hardness of the workpiece as a whole has been used in the past. However, no solution has been proposed for heat treatment of the workpiece to have both a high hardness region and a low hardness region. Summary of the invention

[0006] The present invention has been made in view of such circumstances, and an object of the present invention is to provide a technique capable of suitably applying heat treatment in which a high hardness region and a low hardness region appear in a workpiece of a reduction gear assembly.

[0007] One embodiment of the present invention relates to a speed reducer assembly, which is provided with a high hardness region and a low hardness region whose surface hardness is lower than that of the high hardness region, wherein the low hardness region is provided within a range where a load applied during operation of the speed reducer is smaller than that of the high hardness region.

[0008] Another embodiment of the present invention also relates to a heat treatment method for a reduction gear assembly. The method includes a heat treatment process for heat treating the reduction gear assembly by irradiating a laser from a head, in which the reduction gear assembly is irradiated with laser for quenching to form a high hardness area, and then a part of the range irradiated with the laser is irradiated with the laser again to form a low hardness area, and the re-irradiation range of the laser is set so that the load applied when the reduction gear is running is smaller than the range of the high hardness area.

[0009] According to the present invention, it is possible to suitably employ heat treatment in which a high hardness region and a low hardness region appear on a workpiece of a speed reduction device component. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a cross-sectional view showing the reduction gear transmission according to the first embodiment.

[0011] Figure 2 It is a cross-sectional view showing an eccentric body and an eccentric body bearing according to the first embodiment in an enlarged manner.

[0012] Figure 3 This is a perspective view of each eccentric body according to the first embodiment as seen from the upper front side.

[0013] Figure 4 This is a perspective view of each eccentric body according to the first embodiment as seen from the lower back side.

[0014] Figure 5 It is a side view of each eccentric body in the first embodiment.

[0015] Figure 6 It is a top view of each eccentric body in the first embodiment.

[0016] Figure 7 is along Figure 5 Sectional view taken along line AA.

[0017] Figure 8 is along Figure 5 Cross-sectional view taken along line BB.

[0018] 9( a ) and 9 ( b ) are diagrams for explaining the heat treatment method of the eccentric body according to the first embodiment.

[0019] Fig.10 It is a cross-sectional view showing a reduction gear transmission according to a second embodiment.

[0020] Fig.11 It is a diagram showing the outer peripheral surface of the vibrator according to the second embodiment in a cross section perpendicular to the axial direction.

[0021] In the figure: 10-reduction device, 16-A-first eccentric body, 16-B-second eccentric body, 20-external gear, 26-rolling body, 46-eccentric body connecting portion, 46a-first outer peripheral surface, 46b-second outer peripheral surface, 48-first high hardness area, 50-first low hardness area, 52-second high hardness area, 54-second low hardness area, 56-hollow portion, 116-vibrator, 120-external gear, 128-rolling body. DETAILED DESCRIPTION

[0022] In the following, in the embodiments and the modified examples, the same constituent elements are marked with the same symbols, and repeated descriptions are omitted. In addition, in each of the drawings, for the convenience of description, part of the constituent elements is appropriately omitted, or the size of the constituent elements is appropriately enlarged or reduced. In addition, for different constituent elements that have common points, they are distinguished by marking "1st, 2nd" at the beginning of the name and "-A, -B" at the end of the symbol, and they are omitted when collectively referred to.

[0023] (First embodiment)

[0024] Figure 1 1 is a cross-sectional view showing the reduction gear 10 of the first embodiment. The reduction gear 10 of the present embodiment is an eccentric oscillating type reduction gear that causes an oscillating gear meshing with a meshing gear to oscillate by an eccentric body, thereby causing the oscillating gear to rotate and output its rotational component. The reduction gear 10 of the present embodiment is an external tooth oscillating type reduction gear in which the meshing gear is an internal gear 22 and the oscillating gear is an external gear 20.

[0025] The reduction gear 10 mainly includes a housing 12 , an input shaft 14 , an eccentric body 16 , an eccentric body bearing 18 , an external gear 20 , an internal gear 22 , and a carrier 24 .

[0026] Internal components of the reduction gear device 10 , such as an eccentric body 16 , are accommodated in the housing 12 .

[0027] The input shaft 14 is rotated by the driving of a drive shaft of a driving device such as a motor. The input shaft 14 rotates with its own axis as the rotation center. The input shaft 14 of this embodiment is integrated with the drive shaft.

[0028] The eccentric body 16 is provided on the input shaft 14 via a key or the like so as to be integrally rotatable with the input shaft 14. The eccentric body 16 rotates about a rotation center line Lc passing through the rotation center of the input shaft 14, thereby causing the external gear 20 to oscillate.

[0029] Figure 2 It is a cross-sectional view showing the eccentric body 16 and the eccentric body bearing 18 in an enlarged manner. The eccentric body 16 of the present embodiment includes a first eccentric body 16-A and a second eccentric body 16-B adjacent to each other along the rotation center line Lc (axial direction). The eccentric body bearing 18, the external gear 20 and the internal gear 22 are provided in a set corresponding to the first eccentric body 16-A, and in a set corresponding to the second eccentric body 16-B. The corresponding components are distinguished by marking "1st, 2nd" at the beginning of the name and "-A, -B" at the end of the symbol. The details of the eccentric body 16 will be described later.

[0030] The eccentric bearing 18 includes a plurality of rolling elements 26 and a retainer 28. The eccentric bearing 18 is positioned in the axial direction by a stopper (not shown) or the like. The retainer 28 maintains the relative positions of the plurality of rolling elements 26 and supports the plurality of rolling elements 26 rotatably.

[0031] The rolling element 26 is arranged between the external gear 20 and the eccentric body 16, that is, between the swing gear and the eccentric body 16. The rolling elements 26 are arranged around the rotation center line Lc at intervals from each other in the circumferential direction. The rolling element 26 of this embodiment is a roller. In detail, the rolling element 26 is a cylindrical roller having a rotation axis parallel to the rotation center line Lc.

[0032] The eccentric body bearing 18 of this embodiment does not have a dedicated inner ring and outer ring. Instead, the outer peripheral surface of the eccentric body 16 plays the role of the inner ring, and the inner peripheral surface of the through hole 20a (described later) of the external gear 20 plays the role of the outer ring. That is, the outer peripheral surface of the eccentric body 16 constitutes the inner rolling surface 30 that allows the rolling element 26 to roll in the circumferential direction. In addition, the inner peripheral surface of the external gear 20 constitutes the outer rolling surface that allows the rolling element 26 to roll in the circumferential direction.

[0033] Return to Figure 1 . The eccentric body 16 can cause the external gear 20 to swing around the rotation center line L c via the rolling body 26. The external gear 20 meshes with the inner gear 22 while swinging. A through hole 20a is formed in the external gear 20, which penetrates the external gear 20 in the axial direction, and the eccentric body 16 and the rolling body 26 are arranged on the inner side of the through hole 20a. A plurality of pin holes 20b are formed in the external gear 20. Each pin hole 20b is arranged at a position radially offset from the rotation center line L c and is arranged to be spaced apart from each other in the circumferential direction. An inner pin 32 is fitted into each pin hole 20b with a gap. An inner roller 34 is rotatably assembled on the outer peripheral side of the inner pin 32.

[0034] The internal gear 22 of the present embodiment includes an internal gear body 36 integrated with the housing 12, an outer pin 38 supported by the internal gear body 36, and an outer roller 40 rotatably assembled to the outer peripheral side of the outer pin 38. The outer roller 40 constitutes the internal teeth of the internal gear 22. In the present embodiment, the number of internal teeth of the internal gear 22 (the number of outer rollers 40) is one more than the number of external teeth of the external gear 20.

[0035] The wheel carrier 24 is arranged on one side in the axial direction of the external gear 20. The wheel carrier 24 can rotate synchronously with the rotation component of the external gear 20. For this purpose, a pin retaining hole 24a is formed in the wheel carrier 24 for pressing the inner pin 32, and the rotation component of the external gear 20 is transmitted to the wheel carrier 24 via the inner pin 32. The wheel carrier 24 is integrated with an output shaft 44 that is supported by the housing 12 so as to be rotatable via an output bearing 42.

[0036] Next, the operation of the reduction gear 10 will be described. When the drive shaft rotates, the input shaft 14 rotates together with the drive shaft. When the input shaft 14 rotates, the eccentric body 16 rotates together with the input shaft 14 around the rotation center line Lc. When the eccentric body 16 rotates around the rotation center line Lc, the external gear 20 is swung via the rolling element 26. When the external gear 20 swung, the meshing position of the external gear 20 and the internal gear 22 is sequentially shifted. As a result, for each rotation of the input shaft 14, the external gear 20 rotates relative to the internal gear 22 (i.e., rotates) by an amount corresponding to the difference in the number of teeth between the external gear 20 and the internal gear 22. The self-rotation component of the external gear 20 is transmitted to the wheel carrier 24 via the inner roller 34 and the inner pin 32, and is transmitted to the output shaft 44 integrated with the wheel carrier 24. As a result, the rotation of the input shaft 14 is decelerated at a reduction ratio corresponding to the difference in the number of teeth between the external gear 20 and the internal gear 22 and the number of teeth of the swing gear, and is output from the output shaft 44.

[0037] Figure 3 This is a perspective view of each eccentric body 16 as seen from the upper front side. Figure 4 This is a perspective view of each eccentric body 16 as seen from the lower back side. Figure 5 It is a side view of the eccentric body 16. Figure 6 It is a top view of the eccentric body 16. In these figures, the first low hardness area 50 and the second low hardness area 54 described later are indicated by hatching. As mentioned above, the eccentric body 16 includes the first eccentric body 16-A and the second eccentric body 16-B. The first eccentric body 16-A is the first rotating body that causes the first external gear 20-A to swing, and the second eccentric body 16-B is the second rotating body that causes the second external gear 20-B to swing. An eccentric body connecting portion 46 that connects the first eccentric body 16-A and the second eccentric body 16-B is provided between the first eccentric body 16-A and the second eccentric body 16-B. The first eccentric body 16-A, the second eccentric body 16-B and the eccentric body connecting portion 46 are an integrally formed one-piece product. The integrally formed product can be obtained by cutting or the like. The integrally formed product uses steel (i.e., metal) such as high carbon chromium steel as a raw material.

[0038] Figure 7 is along Figure 5 The sectional view of the AA line. Figure 7In the figure, the eccentric body bearing 18 is also shown. The eccentric body 16 is cylindrical, and in the present embodiment, its outer peripheral surface is circular. The outer peripheral surface of the eccentric body 16 is eccentric with respect to the rotation center line Lc by a predetermined eccentricity e. The phase difference between the maximum eccentricity direction Pa of the first eccentric body 16-A and the second eccentric body 16-B is 180 degrees. The maximum eccentricity direction Pa of the eccentric body 16 here refers to: the direction from the rotation center line Lc toward the direction in which the eccentricity e is generated. From another point of view, the maximum eccentricity direction Pa of the eccentric body 16 refers to: the direction extending from the rotation center line Lc of the eccentric body 16 toward the axis Cp of the eccentric body 16. The axis Cp of the eccentric body 16 here refers to: the center of gravity of the shape of the outer peripheral surface of the eccentric body 16 on the cross section of the eccentric body 16 that is orthogonal to the axial direction. In the present embodiment, since the shape of the outer peripheral surface of the eccentric body 16 is circular, the center of the circle is the axis Cp of the eccentric body 16.

[0039] Figure 8 is along Figure 5 The cross-sectional view of the BB line. Figure 5 and Figure 8 As shown, the eccentric body connection portion 46 is formed into a cylindrical shape having an outer shape different from the outer shapes of the first eccentric body 16-A and the second eccentric body 16-B. The eccentric body connection portion 46 has a first outer peripheral surface 46a that is continuous with the outer peripheral surface of the first eccentric body 16-A in the axial direction and a second outer peripheral surface 46b that is continuous with the outer peripheral surface of the second eccentric body 16-B in the axial direction. Of the two half peripheral surfaces constituting the entire outer peripheral surface of the eccentric body connection portion 46, the first outer peripheral surface 46a constitutes one half peripheral surface, and the second outer peripheral surface 46b constitutes the other half peripheral surface. The entire circumference of the outer peripheral surface of the eccentric body connection portion 46 is composed of the first outer peripheral surface 46a and the second outer peripheral surface 46b.

[0040] A curvature changing portion 46c is provided at the boundary portion between the first outer peripheral surface portion 46a and the second outer peripheral surface portion 46b. On the cross section of the eccentric body connecting portion 46 which is orthogonal to the axial direction, the curvature changing portion 46c is a boundary where the curvature changes from the first outer peripheral surface portion 46a to the curvature of the second outer peripheral surface portion 46b. The curvature changing portion 46c is in an angular shape protruding toward the outside. The curvature changing portion 46c extends from the second eccentric body 16-B to the first eccentric body 16-A as it moves from the first outer peripheral surface portion 46a toward the second outer peripheral surface portion 46b.

[0041] Here, a first high hardness region 48 and a first low hardness region 50 are provided on the outer peripheral surface of each eccentric body 16. Figure 3 to Figure 6In the figure, the unhatched portion of the outer peripheral surface of the eccentric body 16 is the first high hardness region 48, and the hatched portion is the first low hardness region 50. In the present embodiment, a first high hardness region 48 is provided on each eccentric body 16, and a first low hardness region 50 is provided in other portions. The first low hardness region 50 is a region whose surface hardness is lower than the surface hardness of the first high hardness region 48. The surface hardness here refers to the hardness of the surface layer including the outer peripheral surface of the eccentric body 16. In detail, the surface hardness refers to the average value of the total hardness measured according to a prescribed unit depth (for example, 0.1 mm) for a range (for example, 1.0 mm) from the outer peripheral surface of the eccentric body 16 to a prescribed depth in the depth direction (normal direction). The hardness difference between the first high hardness region 48 and the first low hardness region 50 is, for example, at least 50 Hv in Vickers hardness. In the case of heat treatment by laser quenching described later as in the present embodiment, the hardness difference is usually 150 Hv or more.

[0042] As described later, the first high hardness region 48 can be obtained by quenching the raw material of the eccentric body 16 by laser quenching or the like. A quenched structure having, for example, martensite as a main phase is provided on the surface of the first high hardness region 48. As described later, the first low hardness region 50 can be obtained by quenching the raw material of the eccentric body 16 by laser quenching or the like and then quenching the same portion again. A tempered structure having, for example, a mixed structure of ferrite and austenite as a main phase is provided on the surface of the first low hardness region 50.

[0043] In this embodiment, if Figure 7 As shown, a non-load range Sa is defined as the range where the first low hardness area 50 should be set. The non-load range Sa is a range of ±90 degrees from the first reference line Lb1 extending from the axis Cp of the eccentric body 16 toward the opposite maximum eccentricity direction Pb in the range around the axis Cp of the eccentric body 16. The opposite maximum eccentricity direction Pb here refers to: a direction extending from the rotation center line Lc in the direction exactly opposite to the maximum eccentricity direction Pa. Non-load ranges Sa are defined in the first eccentric body 16-A and the second eccentric body 16-B, respectively. Since the phase difference between the first eccentric body 16-A and the second eccentric body 16-B is 180 degrees, the non-load range Sa of the second eccentric body 16-B is set at a position that deviates from the non-load range Sa of the first eccentric body 16-A by 180 degrees (not shown). The first low hardness area 50 is set so that its entirety falls within the non-load range Sa. The reason for this is explained below.

[0044] In the positive direction of the eccentric body 16 ( Figure 7When the eccentric body 16 rotates in the clockwise direction (in the direction of rotation), the maximum load is applied from the rolling element 26 to a certain position within the range Sb of -90 degrees from the second reference line Lb2 extending toward the maximum eccentric direction Pa, and almost no load is applied to the other ranges. Figure 7 When the eccentric body 16 rotates in the counterclockwise direction (in the direction of rotation), the maximum load is applied from the rolling element 26 to a certain position within the range Sc of +90 degrees from the second reference line Lb2 extending toward the maximum eccentric direction Pa, and almost no load is applied to the other ranges. That is, in the eccentric body 16, regardless of the rotation direction of the eccentric body 16, almost no load is applied to the non-load range Sa of ±90 degrees from the first reference line Lb1 extending toward the opposite maximum eccentric direction Pb.

[0045] If the first low hardness region 50 is provided within the non-load range Sa, a large load will not be applied to the first low hardness region 50, and the life of the eccentric body 16 can be prevented from being reduced due to the first low hardness region 50. Therefore, even if a heat treatment (for example, laser quenching) is performed on the workpiece of the rotating body (eccentric body 16) that becomes a component for a reduction gear, in which a high hardness region and a low hardness region are formed, the influence of the low hardness region on the service life can be eliminated. Therefore, according to the present embodiment, a heat treatment in which a high hardness region and a low hardness region are formed can be well applied to the workpiece of the component for a reduction gear.

[0046] In addition, the first low hardness region 50 is preferably provided in a range Sd (not shown) near the position where the first reference line Lb1 passes in the outer peripheral surface of the eccentric body 16. The range Sd refers to a range of ±30 degrees from the first reference line Lb1. When the eccentric body 16 rotates, the load from the rolling element 26 is particularly difficult to be applied to the range Sd of the eccentric body 16. Therefore, by providing the first low hardness region 50 in the range Sd, it is possible to more effectively prevent the life reduction caused by the first low hardness region 50.

[0047] Next, other features of the reduction gear device 10 will be described.

[0048] like Figure 6 As shown, the first low hardness region 50 is provided over the entire axial length of each eccentric body 16. The first low hardness region 50 is in a band shape extending in the axial direction of the eccentric body 16 and inclined with respect to the axial direction of the eccentric body 16.

[0049] Here, attention is paid to the contact line Ld between the rolling surface 30 of the eccentric body 16 and the rolling element 26. The contact line Ld refers to the portion where the rolling surface 30 and the rolling element 26 are in linear contact when the rolling element 26 rolls on the rolling surface 30 of the eccentric body 16. At this time, the width and inclination angle of the band presented by the first low hardness region 50 are set so that when the contact line Ld passes over the first low hardness region 50, the contact line Ld passes over the first high hardness region 48 at the same time. That is, the width and inclination angle of the band presented by the first low hardness region 50 are set so that the contact line Ld does not pass only over the first low hardness region 50, but passes over both the first high hardness region 48 and the first low hardness region 50 at the same time.

[0050] This condition is satisfied when the contact line Ld can pass through all circumferential ranges above the first low hardness area 50 in the entire circumferential range of the rolling surface 30. The narrower the width of the band-shaped first low hardness area 50, or the larger the inclination angle of the band-shaped first low hardness area 50, the easier it is to satisfy this condition. The width of the band-shaped first low hardness area 50 does not need to be constant over the entire axial length of the eccentric body 16, and the width may also vary according to the axial position. The width here refers to the circumferential dimension of the eccentric body 16. The inclination angle here refers to the inclination angle of the length direction of the belt relative to the axial direction of the eccentric body 16 when the belt formed by the first low hardness area 50 on the outer peripheral surface of the eccentric body 16 is unfolded on a plane.

[0051] Thus, when the rolling element 26 contacts the first low hardness region 50 of the eccentric body 16, the rolling element 26 can also contact the first high hardness region 48. Therefore, compared with the case where the rolling element 26 contacts only the first low hardness region 50 of the eccentric body 16, the load applied to the first low hardness region 50 of the eccentric body 16 can be suppressed, thereby achieving a longer life of the eccentric body 16.

[0052] refer to Figure 3 to Figure 6 A second high hardness region 52 and a second low hardness region 54 are provided on the outer peripheral surface of the eccentric body connection portion 46. Figure 3 to Figure 6In the figure, the portion of the outer peripheral surface of the eccentric body connection portion 46 that is not shaded is the second high hardness region 52, and the portion that is shaded is the second low hardness region 54. The relationship between these second high hardness region 52 and second low hardness region 54 is the same as the relationship between the first high hardness region 48 and the first low hardness region 50. That is, the second low hardness region 54 is a region whose surface hardness is lower than the surface hardness of the second high hardness region 52. The surface hardness here refers to the hardness of the surface portion including the outer peripheral surface of the eccentric body connection portion 46, which is the same as described above. The hardness difference between the second high hardness region 52 and the second low hardness region 54 is, for example, at least 50 Hv in Vickers hardness. In the case of heat treatment by laser quenching described later as in the present embodiment, the hardness difference is usually 150 Hv or more.

[0053] The second low hardness region 54 includes a first region portion 54a, a second region portion 54b, and a third region portion 54c. The first region portion 54a is continuous with the first low hardness region 50 of the first eccentric body 16-A in the axial direction. The first region portion 54a is provided at the circumferentially central portion (i.e., the circumferentially intermediate portion) of the first outer peripheral surface portion 46a of the eccentric body connecting portion 46. The second region portion 54b is continuous with the first low hardness region 50 of the second eccentric body 16-B in the axial direction. The second region portion 54b is provided at the circumferentially central portion (i.e., the circumferentially intermediate portion) of the second outer peripheral surface portion 46b of the eccentric body connecting portion 46.

[0054] The third region portion 54c is provided at a boundary portion between the first outer peripheral surface portion 46a and the second outer peripheral surface portion 46b of the eccentric body connecting portion 46. Specifically, the third region portion 54c is provided at one boundary portion and the other boundary portion between the first outer peripheral surface portion 46a and the second outer peripheral surface portion 46b of the eccentric body connecting portion 46. The curvature changing portion 46c is provided at the boundary portion, and the third region portion 54c is provided along the curvature changing portion 46c.

[0055] As described later, the eccentric body connection portion 46 is obtained by the following two processes: a heat treatment process for setting the first high hardness region 48 on the outer peripheral surface of the first eccentric body 16-A, and a heat treatment process for setting the first high hardness region 48 on the outer peripheral surface of the second eccentric body 16-B. That is, there is no need to perform a heat treatment process for hardening the eccentric body connection portion 46 in addition to the heat treatment process for the first eccentric body 16-A and the second eccentric body 16-B. Therefore, for a component having multiple eccentric bodies 16, the entire eccentric body 16 can be hardened by a small number of heat treatment hours.

[0056] refer to Figure 2A hollow portion 56 and a first lubricating oil passage 58 are provided inside the eccentric body 16. The hollow portion 56 extends in the axial direction, and the input shaft 14 is inserted into the hollow portion 56. A portion of the hollow portion 56 of the eccentric body 16 is arranged at a position lower than the oil level of the lubricating oil sealed in the housing 12 in a static state. The lubricating oil may be oil or grease.

[0057] The first lubricating oil passage 58 extends radially from the hollow portion 56 and has a discharge port 58a opened on the outer peripheral surface of the eccentric body 16. When the eccentric body 16 rotates, the lubricating oil flows into the first lubricating oil passage 58 through the interior of the hollow portion 56 of the eccentric body 16. The lubricating oil flows into the first lubricating oil passage 58 through a second lubricating oil passage (not shown) formed between the hollow portion 56 of the eccentric body 16 and the input shaft 14 or formed inside the input shaft 14 and extending in the axial direction. If the eccentric body 16 rotates in this state, centrifugal force acts on the lubricating oil in the first lubricating oil passage 58. As a result, the lubricating oil in the hollow portion 56 of the eccentric body 16 is sucked into the first lubricating oil passage 58, and the lubricating oil is discharged from the discharge port 58a of the first lubricating oil passage 58, whereby the eccentric body bearing 18 and the surrounding components are lubricated by the lubricating oil.

[0058] Here, if Figure 3 , Figure 4 and Figure 6 As shown, the discharge port 58a of the first lubricating oil passage 58 opens in the first low hardness region 50 of the eccentric body 16. The discharge port 58a is formed in a shape that falls entirely in the first low hardness region 50, and is not formed in the first high hardness region 48. As a result, the opening edge of the discharge port 58a becomes low hardness, so it is easier to ensure durability compared to the case where the discharge port 58a opens in the first high hardness region 48. In addition, compared to the case where the discharge port 58a opens in the first high hardness region 48, it is easier to process the discharge port 58a on the outer peripheral surface of the eccentric body 16, thereby achieving good workability.

[0059] Next, a method for heat treating the eccentric body 16 will be described.

[0060] 9(a) and 9(b) are diagrams for explaining a heat treatment method of the eccentric body 16. In the present embodiment, heat treatment is performed by laser quenching using a laser. If laser quenching is used, there are the following advantages: no need for cooling equipment for rapid cooling, less burden on the environment, less heat treatment strain, etc.

[0061] The eccentric body 16 as a workpiece to be heat treated is supported by a rotating jig (not shown) so as to be rotatable about the axis Cp. In this state, the laser beam 62 is irradiated from the head 60 to quench the outer peripheral surface of the eccentric body 16 .

[0062] When the eccentric body 16 is heat treated, the first heat treatment step of the first eccentric body 16-A and the second heat treatment step of the second eccentric body 16-B are respectively performed. In the first heat treatment step, as shown in FIG9(a), the laser 62 is irradiated to the entire axial length of the outer peripheral surface of the first eccentric body 16-A and the entire axial length of the first outer peripheral surface 46a of the eccentric body connecting portion 46. In this step, the laser irradiation position on the first eccentric body 16-A is changed along the circumference of the first eccentric body 16-A, so that the entire circumference of the outer peripheral surface of the first eccentric body 16-A is quenched in one step. To this end, the first eccentric body 16-A is rotated around its own axis Cp by a rotating fixture without changing the radial position of the head 60 relative to the first eccentric body 16-A. Thus, the laser is irradiated while keeping the distance from the head 60 to the irradiation position on the first eccentric body 16-A (hereinafter referred to as the irradiation distance) substantially constant. By this one-step quenching, not only the outer peripheral surface of the first eccentric body 16-A but also the first outer peripheral surface portion 46a of the eccentric body connecting portion 46 is quenched.

[0063] In the second heat treatment process, as shown in FIG9(b), the laser 62 is irradiated over the entire axial length of the outer peripheral surface of the second eccentric body 16-B and the entire axial length of the second outer peripheral surface 46b of the eccentric body connecting portion 46. In this process, the laser irradiation position on the second eccentric body 16-B is changed along the circumference of the second eccentric body 16-B, so that the entire circumference of the outer peripheral surface of the second eccentric body 16-B is quenched in one step. To this end, the second eccentric body 16-B is rotated around its own axis Cp by a rotating fixture. Through this one-step quenching, not only the outer peripheral surface of the second eccentric body 16-B is quenched, but also the second outer peripheral surface 46b of the eccentric body connecting portion 46 is quenched.

[0064] In the first heat treatment step and the second heat treatment step, the laser irradiation position on the eccentric body 16 is changed in the circumferential direction, thereby quenching the entire circumference of the outer peripheral surface of the eccentric body 16, and then the laser is irradiated again on a part of the range irradiated with the laser. Thus, the first low hardness area 50 called the softened area is set by tempering in the laser re-irradiated range.

[0065] The laser re-irradiation range on the outer peripheral surface of the eccentric body 16 is, for example, a range of several millimeters from the laser irradiation start position on the eccentric body 16. The re-irradiation range is set so that it falls within the non-load range Sa of the eccentric body 16 mentioned above. That is, the re-irradiation range is set so that it falls within the range of ±90 degrees from the first reference line Lb1 extending from the axis Cp of the eccentric body 16 in the direction opposite to the maximum eccentricity Pb ​​in the range around the axis Cp of the eccentric body 16. Thus, the first low hardness area 50 is set in the non-load range Sa of the eccentric body 16, and the first high hardness area 48 is set in the other range of the outer peripheral surface of the eccentric body 16.

[0066] In both the first and second heat treatment steps, the position of the head 60 and the irradiation angle of the laser from the head 60 are adjusted so that the softened region is in the shape of a band inclined relative to the axial direction of the eccentric body 16. Thus, the first low hardness region 50 in the shape of a band inclined relative to the axial direction of the eccentric body 16 is provided.

[0067] When the first eccentric body 16-A is rotated around the axis Cp in the first heat treatment process, the irradiation distance from the head 60 to the first eccentric body 16-A and the irradiation distance from the head 60 to the first outer peripheral surface 46a of the eccentric body connection part 46 are equal regardless of the rotational position of the first eccentric body 16-A. On the other hand, the irradiation distance from the head 60 to the second outer peripheral surface 46b of the eccentric body connection part 46 becomes smaller than the above-mentioned irradiation distance from the head 60 to the first eccentric body 16-A and the irradiation distance from the head 60 to the first outer peripheral surface 46a of the eccentric body connection part 46. As a result, in the eccentric body connection part 46, the entire first outer peripheral surface 46a is quenched, while the second outer peripheral surface 46b is not quenched. At this time, the range of the first outer peripheral surface 46a including the curvature change portion 46c on both sides in the circumferential direction is quenched.

[0068] When the intermediate product thus obtained is subjected to the second heat treatment step, the entire second outer peripheral surface 46b of the eccentric body connecting portion 46 is quenched. At this time, the curvature change portion 46c of the second outer peripheral surface 46b is irradiated again. Thus, the third region portion 54c of the second low hardness region 54 is provided in the curvature change portion 46c of the eccentric body connecting portion 46 and its surrounding portion.

[0069] (Second embodiment)

[0070] Fig.10 1 is a cross-sectional view showing a reduction gear 10 according to a second embodiment. The reduction gear 10 according to this embodiment is a flexural meshing type reduction gear that flexibly deforms and rotates an external gear 120 meshing with an internal gear 122 to cause the external gear 120 to rotate and output the rotational component.

[0071] The reduction gear 10 mainly includes a housing 112 , a pair of carriers 114 , a vibrator 116 , a vibrator bearing 118 , an external gear 120 , and an internal gear 122 .

[0072] The housing 112 is a cylindrical member, and a pair of wheel carriers 114 are arranged inside the housing 112. The pair of wheel carriers 114 are rigid cylindrical members, and a vibrator 116 is arranged inside the housing 112. The pair of wheel carriers 114 are arranged at intervals from each other in the axial direction of the vibrator 116. Fig.10 The wheel frame on the right side of the middle (hereinafter referred to as the input side wheel frame 114-A) is assembled to the housing 112 in a non-rotatable manner, and is connected to a drive device such as a motor by means of bolts (not shown) screwed into bolt holes 114a. The other side wheel frame 114-B ( Fig.10 The wheel carrier on the left side of the middle wheel carrier (hereinafter referred to as the output side wheel carrier 114-B) is rotatably supported by the housing 112 via the main bearing 124. The output side wheel carrier 114-B functions as an output portion for outputting the rotation input from the drive device.

[0073] The vibrator 116 is a cylindrical component, and the shape of its cross section perpendicular to the axis is an ellipse. In the present application, the ellipse is not limited to a strict geometric ellipse, and it also includes a roughly ellipse with a major axis and a minor axis. The vibrator 116 is doubly supported by a pair of wheel frames 114 via bearings 126 so as to be rotatable. A drive shaft of a driving device is connected to the vibrator 116. The vibrator 116 functions as an input shaft that rotates with its own axis as the center of rotation through the drive of the drive shaft. In addition, the vibrator 116 functions as a rotating body that causes the external gear 120 to bend and deform.

[0074] The vibrator bearing 118 is disposed between the vibrator 116 and the external gear 120. The vibrator bearing 118 includes a first vibrator bearing 118-A that rotatably supports a first external tooth portion 120b (to be described later) of the external gear 120 and a second vibrator bearing 118-B that rotatably supports a second external tooth portion 120c (to be described later) of the external gear 120.

[0075] The vibrator bearing 118 includes a plurality of rolling elements 128, a retainer 130, and an outer ring 132. The retainer 130 maintains the relative positions of the plurality of rolling elements 128 and supports the plurality of rolling elements 128 to be rotatable. The outer ring 132 is disposed on the outer peripheral side of the plurality of rolling elements 128. The outer ring 132 has flexibility and is bent and deformed into an elliptical shape by the vibrator 116 via the plurality of rolling elements 128, similar to the external gear 120.

[0076] The rolling element 128 is disposed between the vibrator 116 and the external gear 120. The rolling element 128 is disposed around the rotation center line Le extending along the rotation center of the vibrator 116 and is disposed to be spaced apart from each other in the circumferential direction. The rolling element 128 of this embodiment is a roller. Specifically, the rolling element 128 is a cylindrical roller having a rotation axis parallel to the rotation center line Le.

[0077] The vibrator bearing 118 of the present embodiment does not have a dedicated inner ring. Instead, the outer peripheral surface of the vibrator 116 performs the function of the inner ring. The outer peripheral surface of the vibrator 116 constitutes an inner rolling surface 134 for rolling the rolling element 128. In detail, the outer peripheral surface of the vibrator 116 has a first inner rolling surface 134-A for rolling the first rolling element 128-A of the first vibrator bearing 118-A and a second inner rolling surface 134-B for rolling the second rolling element 128-B of the second vibrator bearing 118-B. The first inner rolling surface 134-A and the second inner rolling surface 134-B are continuous in the axial direction and have the same cross-sectional shape.

[0078] The external gear 120 is arranged on the outer peripheral side of the vibrator 116. The external gear 120 is a flexible annular member. The external gear 120 is bent and deformed into an elliptical shape by the vibrator 116 via a plurality of rolling elements 128. The two side portions of the external gear 120 in the long axis direction of the vibrator 116 mesh with the inner part of the internal gear 122. The external gear 120 has a cylindrical base 120a, a first external tooth portion 120b and a second external tooth portion 120c integrally formed on the outer peripheral side of the base 120a. The first external tooth portion 120b is arranged on one side in the axial direction, and the second external tooth portion 120c is arranged on the other side in the axial direction. If the vibrator 116 rotates, the meshing position of the external gear 120 and the internal gear 122 is displaced in the circumferential direction, and the external gear 120 is bent and deformed corresponding to the shape of the vibrator 116.

[0079] The internal gear 122 is a rigid annular component. The internal gear 122 is arranged on the outer peripheral side of the external gear 120. The internal gear 122 includes a first internal gear 122-A that meshes with the first external tooth portion 120b of the external gear 120 and a second internal gear 122-B that meshes with the second external tooth portion 120c of the external gear 120. The number of internal teeth of the first internal gear 122-A is 2i (i is a natural number greater than 1) more than the number of external teeth of the first external tooth portion 120b, and the number of internal teeth of the second internal gear 122-B is consistent with the number of external teeth of the second external tooth portion 120c. The first internal gear 122-A is formed integrally with the input side wheel frame 114-A, and the second internal gear 122-B is formed integrally with the output side wheel frame 114-B.

[0080] Next, the operation of the reduction gear device 10 will be described.

[0081] If the drive shaft rotates, the vibrator 116 rotates together with the drive shaft. If the vibrator 116 rotates, the meshing position of the external gear 120 and the internal gear 122 is displaced in the circumferential direction, and the external gear 120 is flexed and deformed corresponding to the shape of the vibrator 116. Every time the vibrator 116 rotates one circle, the first external tooth portion 120b rotates (rotates) relative to the first internal gear 122-A by an amount equivalent to the difference in the number of teeth between the first external tooth portion 120b and the first internal gear 122-A. At this time, the rotation of the vibrator 116 is reduced in speed by a reduction ratio corresponding to the difference in the number of teeth between the first external tooth portion 120b and the first internal gear 122-A, causing the external gear 120 to rotate.

[0082] The first external tooth portion 120b and the second external tooth portion 120c rotate integrally with the same phase. Since the number of teeth of the second internal gear 122-B is the same as the number of teeth of the second external tooth portion 120c, the relative meshing position of the second internal gear 122-B and the second external tooth portion 120c remains unchanged before and after the vibrator 116 rotates one circle, and the second internal gear 122-B rotates synchronously with the self-rotation component of the first external tooth portion 120b. The self-rotation component of the first external tooth portion 120b is transmitted to the output side wheel frame 114-B via the second internal gear 122-B. As a result, the rotation of the input shaft 14 is decelerated and output from the output side wheel frame 114-B.

[0083] Fig.11 1 is a diagram showing the outer peripheral surface of the vibrator 116 in a cross section perpendicular to the axial direction. Similar to the outer peripheral surface of the eccentric body 16 of the first embodiment, the outer peripheral surface of the vibrator 116 of this embodiment is also provided with a first high hardness region 48 and a first low hardness region 50. Fig.11 In the figure, the portion of the outer peripheral surface of the vibrator 116 that is not shaded is the first high hardness region 48, and the portion shaded is the first low hardness region 50. In the present embodiment, a first low hardness region 50 is provided on the vibrator 116. The relationship between them is the same as that between the first high hardness region 48 and the first low hardness region 50 in the first embodiment.

[0084] In the present embodiment, a non-load range Sa is defined as the range in which the first low hardness region 50 should be set. The non-load range Sa is a range of ±45 degrees from the third reference line Lb3 extending from the rotation center line Le to the short axis direction Pe of the vibrator 116 in the range around the rotation center line Le of the vibrator 116. The short axis direction Pe here refers to: the short axis direction of the ellipse presented by the cross-sectional shape of the vibrator 116. The short axis direction Pe can also be understood as, when the position with the shortest distance from the rotation center line Le of the vibrator 116 to the outer peripheral surface is called the short axis position, the short axis direction Pe is the extension direction of the straight line connecting the two short axis positions. The first low hardness region 50 is set so that its entirety falls within the non-load range Sa. The reasons for this are explained below.

[0085] In the positive direction ( Fig.11 When the vibrator 116 rotates in the clockwise direction (in the clockwise direction), the maximum load is applied to a certain part within the range Se of -45 degrees from the fourth reference line Lb4 extending along the long axis direction Pf from the rotation center line Le, while almost no load is applied to other ranges. Fig.11 When the vibrator 116 rotates in the counterclockwise direction (in the direction of rotation), the maximum load is applied to a certain portion within the range Sf of +45 degrees from the fourth reference line Lb4 extending along the long axis direction Pf, and almost no load is applied to the other ranges. That is, in the vibrator 116, almost no load is applied to the non-load range Sa of ±45 degrees from the third reference line Lb3 extending along the short axis direction Pe from the rotation center line Le.

[0086] If the first low hardness region 50 is provided within the non-load range Sa, a large load will not be applied to the first low hardness region 50, and the life of the oscillator 116 can be prevented from being reduced due to the first low hardness region 50. Therefore, even if a heat treatment is performed on the workpiece of the rotating body (oscillator 116) that becomes a component for a reduction gear, in which a high hardness region and a low hardness region are formed, the influence of the low hardness region on the service life can be eliminated. Therefore, according to the present embodiment, a heat treatment in which a high hardness region and a low hardness region are formed can be well applied to the workpiece of the component for a reduction gear.

[0087] In addition, similarly to the first embodiment, the first low hardness region 50 is in the shape of a band (not shown) extending along the axial direction of the vibrator 116 and tilted relative to the axial direction. Similar to the first embodiment, the width and tilt angle of the band of the first low hardness region 50 are set so that when the contact line Ld between the rolling surface 134 of the vibrator 116 and the rolling element 128 passes over the first low hardness region 50, the contact line Ld also passes over the first high hardness region 48 at the same time (not shown). Thus, when the rolling element 128 contacts the first low hardness region 50 of the vibrator 116, the rolling element 128 can also contact the first high hardness region 48 at the same time.

[0088] As in the first embodiment, the vibrator 116, which is the workpiece to be heat-treated in this embodiment, is also heat-treated by laser quenching using a laser. With respect to the vibrator 116, the range including the first inner rolling surface 134-A and the second inner rolling surface 134-B is heat-treated at the same time. In this heat treatment process, the range in the axial direction of these vibrators 116 including the inner rolling surfaces 134-A and 134-B is irradiated with laser. In this process, by changing the laser irradiation position on the vibrator 116 along the circumferential direction of the vibrator 116, the entire circumference of the outer peripheral surface of the vibrator 116 is quenched in one step.

[0089] At this time, similarly to the first embodiment, the laser irradiation position on the oscillator 116 is changed in the circumferential direction, so that the entire circumference of the outer peripheral surface of the oscillator 116 is quenched, and then a portion of the range irradiated with the laser is irradiated with the laser again. Thus, the first low hardness region 50 called the softened region is provided by tempering in the laser re-irradiated range.

[0090] The laser re-irradiation range on the outer peripheral surface of the vibrator 116 is set so as to fall within the above-mentioned non-load range Sa of the vibrator 116. That is, the re-irradiation range is set so as to fall within the range of ±45 degrees from the third reference line Lb3 extending from the rotation center line Le along the short axis direction Pe of the vibrator 116. Thus, the first low hardness region 50 is provided in the non-load range Sa of the vibrator 116, and the first high hardness region 48 is provided in the other range of the outer peripheral surface of the vibrator 116.

[0091] The examples of the embodiments of the present invention are described in detail above. The embodiments described above are all specific examples when implementing the present invention. The contents of the embodiments do not limit the technical scope of the present invention. Various design changes such as changes, additions, and deletions of constituent elements can be made without departing from the technical idea of ​​the invention specified in the claims. In the above-mentioned embodiments, such contents that can be subjected to design changes are described with expressions such as "implementation methods" and "in implementation methods", but it does not mean that design changes are not allowed without such expressions. In addition, the hatched lines drawn on the cross sections in the accompanying drawings do not limit the material of the objects marked with hatched lines.

[0092] Furthermore, the above describes an example of obtaining the first high hardness region 48 and the first low hardness region 50 of the rotating body (eccentric body 16 and vibrator 116) by laser quenching. However, the present invention is not limited to this, and any heat treatment that can form a high hardness region and a low hardness region in the workpiece can be used, for example, the first high hardness region 48 and the first low hardness region 50 can also be obtained by high-frequency quenching, etc.

[0093] In the first embodiment, an external gear oscillating speed reduction device is described in which the meshing gear is the internal gear 22 and the oscillating gear is the external gear 20. Alternatively, an internal gear oscillating speed reduction device may be used in which the meshing gear is the external gear 20 and the oscillating gear is the internal gear 22.

[0094] In the first embodiment, an example in which the eccentric body 16 and the input shaft 14 are configured as separate bodies has been described. However, the eccentric body 16 and the input shaft 14 may be configured as one body.

[0095] In the first embodiment, the eccentric body 16 is described as the inner ring of the eccentric body bearing 18. However, the eccentric body 16 may not be the inner ring. In this case, the inner ring of the eccentric body bearing 18 constitutes a part of the eccentric body 16, and the outer peripheral surface of the inner ring constitutes the outer peripheral surface of the eccentric body 16.

[0096] In the first embodiment, an example in which the internal teeth of the internal gear 22 are formed by the outer rollers 40 is described, but the present invention is not limited thereto. For example, the internal teeth of the internal gear 22 may be formed on the inner peripheral surface of the housing 12 .

[0097] In the first embodiment, the input shaft 14 is inserted into the hollow portion 56 of the eccentric body 16, but the input shaft 14 may not be inserted. In this case, the hollow portion 56 of the eccentric body 16 can function as a dedicated oil passage for lubricating oil to flow, and its inner diameter may be smaller than that in the embodiment.

[0098] In the first embodiment, a center crank type eccentric oscillating type reduction gear device in which the eccentric body 16 is arranged at the axial center position of the internal gear 22 is described as an example, but the present invention is not limited to this. For example, the present invention can also be applied to a distributed eccentric oscillating type reduction gear device in which a plurality of eccentric bodies are arranged at positions offset from the axial center of the internal gear 22.

[0099] In the second embodiment, a cylindrical flexure meshing speed reduction gear having a plurality of internal gears 122 is exemplified. However, the type of flexure meshing speed reduction gear is not particularly limited, and for example, a so-called cup-type or top-hat-type flexure meshing speed reduction gear having one internal gear may also be used.

[0100] In the second embodiment, the example in which the vibrator 116 also serves as the inner ring of the vibrator bearing 118 is described, but the vibrator 116 may not also serve as the inner ring. In this case, the inner ring of the vibrator bearing 118 constitutes a part of the vibrator 116, and the outer peripheral surface of the inner ring constitutes the outer peripheral surface of the vibrator 116.

[0101] In the above, an example is described in which the rotating body (eccentric body 16, vibrator 116) is rotated around the axis of the rotating body relative to the head 60 when the laser irradiation position on the rotating body is changed along the circumferential direction of the rotating body. However, this is not limited to this, and for example, the head 60 may be rotated around the axis of the rotating body relative to the rotating body.

Claims

1. A component for a reduction gear, characterized in that: The speed reduction device component includes an eccentric body or a vibrating body, The eccentric body or the vibrator is provided with a high hardness area hardened by laser irradiation and a low hardness area formed by re-irradiating a part of the range irradiated with the laser, and the surface hardness of the low hardness area is lower than the surface hardness of the high hardness area. The low hardness area is set within a range where the load applied by the reduction gear during operation is smaller than that of the high hardness area. When the low hardness region is in contact with another component, the high hardness region is also in contact with the other component.

2. The speed reduction device assembly according to claim 1, characterized in that: The difference in hardness between the high hardness region and the low hardness region is 150 Hv or more.

3. The speed reduction device assembly according to claim 1 or 2, characterized in that: The low hardness region has a tempered structure in a surface layer portion.

4. The speed reduction device assembly according to claim 1 or 2, characterized in that: The speed reduction device assembly has a rolling surface for rolling elements. The high hardness region and the low hardness region are provided on the rolling surface.

5. A heat treatment method for a reduction gear component, characterized in that: The speed reduction device component includes an eccentric body or a vibrating body, The method comprises the following steps: heat treating the eccentric body or the vibrator by irradiating the eccentric body or the vibrator with laser light from the head portion; In the heat treatment step, the eccentric body or the oscillator is irradiated with laser light for quenching to form a high hardness area, and then a part of the range irradiated with the laser light is irradiated with the laser light again to form a low hardness area. The laser re-irradiation range is set so that the load applied when the deceleration device is in operation is smaller than the range of the high hardness area. When the low hardness region is in contact with another component, the high hardness region is also in contact with the other component.

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