CN111594582B

CN111594582B - Flexible meshing gear device and manufacturing method thereof

Info

Publication number: CN111594582B
Application number: CN201911369079.4A
Authority: CN
Inventors: 吉田真司; 石塚正幸
Original assignee: Sumitomo Heavy Industries Ltd
Current assignee: Sumitomo Heavy Industries Ltd
Priority date: 2019-02-21
Filing date: 2019-12-26
Publication date: 2023-05-02
Anticipated expiration: 2039-12-26
Also published as: DE102020102403B4; JP7438666B2; JP2023054008A; CN111594582A; JP2020133800A; DE102020102403A1; JP7374361B2

Abstract

The invention aims to optimize the hardness of an internal tooth member. A flexible meshing gear device (1) is provided with: a vibration starting body (10A); an external gear (12) which is deformed by the vibration starting body; an internal gear (23 g) meshed with the external gear; and a main bearing (33) for supporting the internal gear, wherein the internal gear member (23) provided with the internal gear has internal teeth formed on the inner periphery thereof and an inner ring rolling surface (334) provided integrally with the main bearing on the outer periphery thereof, and the internal gear member has, in order from the inner ring rolling surface to the internal teeth: rolling surface hardness parts (H11, H21); hardness sharply reduced portions (H12, H22) whose hardness is sharply reduced from the rolling surface hardness portion; and a hardness increasing section (H13, H23) in which the hardness is increased and the absolute value of the slope of the hardness change is smaller than the absolute value of the slope of the hardness change of the hardness sharply-decreasing section.

Description

Flexible meshing gear device and manufacturing method thereof

The present application claims priority based on japanese patent application No. 2019-029798 filed on date 21 of 2 nd year 2019. The entire contents of this japanese application are incorporated by reference into the present specification.

Technical Field

The present invention relates to a flexible meshing gear device and a method of manufacturing the same.

Background

Conventionally, there is a flex-meshing gear device including a flex-deformed external gear (for example, refer to patent document 1). The external gear is configured such that a vibrator is embedded via a vibrator bearing, and the vibrator rotates on the inner side to be deformed by deflection. Further, the external gear meshes with the rigid internal gear.

In addition, there is a device for reducing the number of components by integrating an inner ring of a bearing for supporting output and input of a decelerated rotation with an internal gear in such a flexible meshing gear device.

Patent document 1: japanese patent laid-open publication No. 2017-106626

As described above, in a member in which an internal gear and an inner ring of a bearing are integrated (hereinafter, referred to as an internal gear member), there are cases where the hardness required for the tooth surface portion of the internal gear and the inner ring of the bearing are different, and therefore, it is desirable to optimize the hardness in accordance with the position of the member.

Disclosure of Invention

The purpose of the present invention is to optimize the hardness of an internal tooth member.

The flex engagement gear device of the present invention comprises:

a vibration starting body; an external gear deformed by the vibration starting body; an internal gear engaged with the external gear; and a main bearing supporting the internal gear, wherein,

the internal gear member provided with the internal gear is formed with internal teeth on its inner periphery and is integrally provided with an inner ring rolling surface of the main bearing on its outer periphery,

the internal tooth member is configured to have, in order from the inner ring rolling surface toward the internal teeth: a rolling surface hardness portion; a rapidly decreasing hardness portion from which the hardness is rapidly decreased; and a hardness increasing portion in which the hardness is increased and the absolute value of the slope of the hardness change is smaller than the absolute value of the slope of the hardness change of the hardness sharply-decreasing portion.

In the method for manufacturing a flexible meshing gear device according to the present invention, the flexible meshing gear device includes: a vibration starting body; an external gear deformed by the vibration starting body; an internal gear engaged with the external gear; and a main bearing for supporting the internal gear, wherein the manufacturing method of the flexible meshing gear device comprises the following steps:

a groove forming step of forming a groove for forming an inner tooth of the internal gear on an inner periphery and forming a material for forming an inner tooth member of an inner ring rolling surface of the main bearing integrally provided on an outer periphery;

a 1 st heat treatment step of performing a 1 st heat treatment on the formation material while leaving a wall thickness on a radially inner side of a position where the internal teeth are formed;

a 2 nd heat treatment step of performing a 2 nd heat treatment on the groove of the forming material for forming the inner ring rolling surface in a state where a wall thickness is left on a radially inner side than a position where the inner teeth are formed after the 1 st heat treatment step; a kind of electronic device with high-pressure air-conditioning system

And an inner peripheral surface forming step of removing the wall thickness at a position radially inward of a position at which the internal teeth are formed after the 2 nd heat treatment step.

According to the present invention, the hardness of the internal tooth member can be optimized.

Drawings

Fig. 1 is a cross-sectional view showing a flexible meshing gear device according to an embodiment of the present invention.

Fig. 2 is an enlarged cross-sectional view showing a peripheral portion of the internal tooth member.

Fig. 3 is a graph showing a hardness distribution in the radial direction of the internal tooth member.

Fig. 4 (a) to (D) are explanatory views showing the respective steps of the method for manufacturing the internal tooth member in this order.

Fig. 5 (a) to (C) are explanatory views sequentially showing the steps of the method for manufacturing the internal tooth member subsequent to fig. 4.

In the figure: 1-flex meshing gear device, 10-starting body shaft, 10A-starting body, 12-external gear, 22g, 23 g-internal gear, 23-internal gear member, 23M-metal block (forming material), 33-main bearing, 231M-through hole, 232M-V groove, 233M-inner peripheral surface, 234, 235-adjacent inner peripheral surface, 331-inner ring, 332-outer ring, 333-rolling body, 334, 335-inner ring rolling surface, H11, H21-rolling surface hardness portion, H12, H22-hardness rapid decrease portion, H13, H23-hardness increase portion, O1-rotary shaft, P-intermediate point.

Detailed Description

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

Flexible meshing gear device

Fig. 1 is a cross-sectional view showing a flex-meshing gear device 1 according to an embodiment of the present invention. In the present specification, a direction along the rotation axis O1 is defined as an axial direction, a direction orthogonal to the rotation axis O1 is defined as a radial direction, and a rotation direction around the rotation axis O1 is defined as a circumferential direction.

As shown in fig. 1, the flexspline gear device 1 includes: a vibrator shaft 10; an external gear 12 deformed by the starting body shaft 10; two

internal gears

22g, 23g meshed with the external gear 12; and a vibrator bearing 15. The flexible-meshed gear device 1 further includes a 1 st housing 22, an internal gear member 23, a 2 nd housing 24, a 1 st housing 26, a 2 nd housing 27, a bearing 31, a bearing 32, a main bearing 33, a sealing O-ring 34, a sealing O-ring 35, a sealing O-ring 38, an oil seal 41, an oil seal 42, and an oil seal 43.

The vibrator shaft 10 is hollow, and has: the oscillation starting body 10A has an elliptical cross section perpendicular to the rotation axis O1; and

shaft portions

10B and 10C provided on both sides in the axial direction of the oscillation starting body 10A, and having a circular outer shape in a cross section perpendicular to the rotation axis O1. In addition, the ellipse is not limited to an ellipse in a strict sense of geometry, and includes a substantially ellipse. The oscillation starting body shaft 10 rotates around the rotation axis O1, and the center of the outer shape of the cross section of the oscillation starting body 10A perpendicular to the rotation axis O1 coincides with the rotation axis O1.

The external gear 12 is made of a flexible cylindrical metal, and has teeth on its outer periphery.

One of the two internal gears (the 1 st internal gear 22g and the 2 nd internal gear 23 g) meshes with a tooth portion on one side of the center in the axial direction of the external gear 12, and the other internal gear meshes with a tooth portion on the other side of the center in the axial direction of the external gear 12. The internal gear 22g is formed by providing internal teeth at corresponding portions of the inner peripheral portion of the 1 st housing 22. The internal gear 23g is configured by providing internal teeth at corresponding portions of the inner peripheral portion of the internal tooth member 23.

The oscillating body bearing 15 is disposed between the oscillating body 10A and the external gear 12. The oscillating body bearing 15 has a plurality of rolling bodies (rollers) 15A, an outer ring 15B, and a cage 15C holding the plurality of rolling bodies 15A. The plurality of rolling elements 15A includes: the 1 st group of rolling elements 15A arranged in a circumferential direction on the radially inner side of the one-side internal gear 22 g; and the 2 nd group of rolling elements 15A are arranged in a circumferential direction on the radially inner side of the other ring gear 23g. The plurality of rolling elements 15A roll with the outer peripheral surface of the starting element 10A and the inner peripheral surface of the outer ring 15B as rolling surfaces.

Spacer rings

36, 37 are provided on both axial sides of the external gear 12, the outer ring 15B, and the retainer 15C, and abut against them to suppress their displacement in the axial direction.

The 1 st housing 22 and the 2 nd housing 24 are coupled to each other and cover the

inner gears

22g, 23g and the radially outer side of the outer gear 12.

The 1 st cover 26 is coupled to the 1 st housing 22 and covers an outer peripheral portion of one end side of the oscillating body shaft 10.

The 2 nd cover 27 covers the outer peripheral portion of the other end side of the oscillating body shaft 10. Bolt connection holes 27h and 23h extending continuously in the axial direction are provided at the load side end portions of the 2 nd housing 27 and the internal tooth member 23. When the flexible meshing gear device 1 is connected to the target device, the 2 nd housing 27 and the internal gear member 23 are fastened together to the driven member of the target device via the bolt-connecting holes 27h and 23h. The bolt connection holes 27h and 23h are provided at a plurality of positions in the circumferential direction. The 2 nd cover 27 and the internal tooth member 23 are further provided with

bolt holes

27j and 23j for temporarily fixing both.

The bearing 31 is, for example, a ball bearing, and is disposed between the shaft portion 10B of the oscillating body shaft 10 and the 1 st housing 26. The 1 st cover 26 rotatably supports the oscillation starting shaft 10 via a bearing 31.

A step h1 whose outer diameter varies greatly is provided at a position (central side in the axial direction) of the oscillating body shaft 10 adjacent to the arrangement portion of the bearing 31. A step h2 whose inner diameter changes little by little is provided at a position (one end side in the axial direction) of the 1 st housing 26 adjacent to the arrangement portion of the bearing 31. In the axial direction, the bearing 31 is disposed between the step h1 and the step h2. The steps h1 and h2 function as stoppers for inhibiting the axial movement of the bearing 31. That is, the bearing 31 is attached to the 1 st housing 26 and the vibrator shaft 10 by a snap fit structure, and the steps h1 and h2 position the bearing 31 in the axial direction.

The bearing 32 is, for example, a ball bearing, and is disposed between the shaft portion 10C of the oscillating body shaft 10 and the 2 nd housing 27. The 2 nd cover 27 rotatably supports the oscillating body shaft 10 via a bearing 32.

A step h3 whose outer diameter varies greatly is provided at a position (central side in the axial direction) of the oscillating body shaft 10 adjacent to the arrangement portion of the bearing 32. A step h4 whose inner diameter changes little by little is provided at a position (one end side in the axial direction) of the 2 nd housing 27 adjacent to the arrangement portion of the bearing 32. In the axial direction, the bearing 32 is disposed between the step h3 and the step h4. The steps h3 and h4 function as stoppers for inhibiting the axial movement of the bearing 32. That is, the bearing 32 is attached to the 2 nd housing 27 and the vibrator shaft 10 by a snap fit structure, and the steps h3 and h4 position the bearing 32 in the axial direction.

The oil seal 41 is disposed at one end in the axial direction between the shaft portion 10B of the oscillating body shaft 10 and the 1 st housing 26, and suppresses outflow of lubricant to the outside in the axial direction.

The oil seal 42 is disposed between the shaft portion 10C of the oscillating body shaft 10 and the 2 nd housing 27 at the other end portion in the axial direction, and suppresses outflow of lubricant to the outside in the axial direction.

The oil seal 43 is disposed between the 2 nd housing 24 and the internal tooth member 23, and suppresses outflow of lubricant from this portion.

The O-

rings

34, 35, 38 for sealing seal the space between the 1 st housing 22 and the 1 st cover 26, the 1 st housing 22 and the 2 nd housing 24, and the internal tooth members 23 and the 2 nd cover 27, respectively, to thereby suppress leakage of lubricant, that is, the internal space (the space where the external gear 12 and the main bearing 33 are located) of the flexible meshing gear device 1 of the present embodiment is a lubricant-sealed space in which lubricant is sealed by the O-

rings

34, 35, 38 and the oil seals 41, 42, 43.

Fig. 2 is an enlarged cross-sectional view of the internal tooth member 23. The main bearing 33 is, for example, a cross roller bearing, and is disposed between the internal gear member 23 and the 2 nd housing 24. The 2 nd housing 24 rotatably supports the internal gear member 23 via the main bearing 33. The main bearing 33 has an inner ring 331 integrated with the internal gear member 23, an outer ring 332 integrated with the 2 nd housing 24, and a plurality of rolling elements 333 arranged between the inner ring 331 and the outer ring 332.

The inner ring 331 has V-shaped grooves (grooves having V-shaped axial cross sections) formed on the outer peripheral surface of the inner tooth member 23 and having an opening angle of 90 ° at the groove bottom. The outer ring 332 has a V-groove formed on the inner peripheral surface of the 2 nd housing 24 and having an opening angle of 90 ° at the bottom of the groove.

The V-shaped grooves of the inner ring 331 and the V-shaped grooves (inverted V-shaped grooves) of the outer ring 332 have the same opening width and face each other. A pair of inner ring rolling surfaces 334, 335 (see fig. 2) inclined in opposite directions are formed inside the V-shaped groove of the inner ring 331, and a pair of outer ring rolling surfaces inclined in opposite directions are formed inside the V-shaped groove of the outer ring 332.

A plurality of rolling elements 333 (i.e., crossed rollers) are disposed inside the V-grooves of the inner ring 331 and the V-grooves of the outer ring 332 at intervals in the circumferential direction. The plurality of rolling elements 333 are alternately arranged in the circumferential direction with the rolling elements having the rolling axis perpendicular to one rolling surface of each V-groove and the rolling elements having the rolling axis perpendicular to the other rolling surface.

As described above, the internal teeth of the internal gear 23g are formed on the inner periphery of the internal gear member 23. The inner ring rolling surface 334 and the inner ring rolling surface 335 of the inner ring 331 of the main bearing 33 are arranged so as to overlap with the internal teeth of the internal gear 23g when viewed in the radial direction. In other words, the internal teeth overlap the inner ring rolling surface 334 and the inner ring rolling surface 335 in the axial direction.

In the example of fig. 2, the entire range in the axial direction of the internal teeth and the entire range in the axial direction of the inner ring rolling surface 334 and the inner ring rolling surface 335 overlapped with each other in the internal tooth 23g are substantially identical with each other when viewed in the radial direction, but a partial range of the internal teeth and a partial range of the inner ring rolling surface 334 or the inner ring rolling surface 335 may be arranged so as to overlap with each other. In this case, at least the inner ring rolling surface 334 or the intermediate point of the inner ring rolling surface 335 in the axial direction preferably overlaps with the internal teeth when viewed in the radial direction.

Further, a 1 st adjacent inner circumferential surface 234 and a 2 nd adjacent inner circumferential surface 235 having an inner diameter larger than the inner diameter of the internal teeth are provided at positions adjacent to the internal teeth in the axial direction of the inner circumference of the internal tooth member 23. The 1 st adjacent inner peripheral surface 234 is provided on the side away from the 1 st housing 22, and its inner diameter is constant except for the chamfer portion of the axial end portion. The 2 nd adjacent inner peripheral surface 235 is provided on the side closer to the 1 st housing 22, and is formed as an inclined surface whose inner diameter gradually increases toward the 1 st housing 22. In addition, only one of the 1 st adjacent inner peripheral surface 234 and the 2 nd adjacent inner peripheral surface 235 may be provided.

[ action of flex-mesh Gear device ]

In the flex-meshing gear device 1, when the rotating motion is input from a motor or the like, not shown, and the oscillating body shaft 10 rotates, the motion of the oscillating body 10A is transmitted to the external gear 12. At this time, the external gear 12 is limited to a shape along the outer peripheral surface of the oscillating body 10A, and flexes into an elliptical shape having a major axis portion and a minor axis portion when viewed from the axial direction. Further, the external gear 12 meshes with the internal gear 22g of the fixed 1 st housing 22 at the long axis portion. Therefore, the external gear 12 does not rotate at the same rotation speed as the oscillating body 10A, but the oscillating body 10A relatively rotates inside the external gear 12. Then, with this relative rotation, the external gear 12 is deformed by flexing so that the long axis position and the short axis position thereof move in the circumferential direction. The period of this deformation is proportional to the rotation period of the vibrator shaft 10.

When the external gear 12 is deformed by deflection, the long axis position thereof moves, and therefore the meshing position of the external gear 12 and the internal gear 22g changes in the rotation direction. Here, when the number of teeth of the external gear 12 is 100 and the number of teeth of the internal gear 22g is 102, the meshing teeth of the external gear 12 and the internal gear 22g are sequentially shifted for each rotation of the meshing position, and the external gear 12 rotates (rotates). With the above-described number of teeth, the rotational motion of the oscillating body shaft 10 is decelerated at a reduction ratio of 100:2 and then transmitted to the external gear 12.

On the other hand, the external gear 12 is also meshed with the other internal gear 23g, and therefore, by the rotation of the oscillating body shaft 10, the meshing position of the external gear 12 and the internal gear 23g is also changed in the rotation direction. On the other hand, since the number of teeth of the internal gear 23g is identical to the number of teeth of the external gear 12, the external gear 12 and the internal gear 23g do not rotate relatively, but the rotational motion of the external gear 12 is transmitted to the internal gear 23g at a reduction ratio of 1:1. Thus, the rotational motion of the vibrator shaft 10 is decelerated at a reduction ratio of 100:2 and then transmitted to the 2 nd internal gear member 23g and the 2 nd cover 27. The rotational motion after the deceleration is output to the target member.

[ hardness distribution of internal tooth Member ]

Fig. 3 is a graph showing the hardness distribution of the internal tooth member 23 in the radial direction. Next, a characteristic hardness distribution of the internal tooth members 23 will be described with reference to fig. 3.

The internal tooth members 23 are made of a metal material (for example, chromium molybdenum steel (SCM material in JIS) or alloy steel for machine structure such as S55C).

As described above, the inner gear member 23 is integrally provided with the inner ring 331 of the main bearing 33 on its outer periphery, and the inner gear 23g is integrally provided on its inner periphery. Therefore, the hardness required for the inner teeth of the internal gear 23g and the inner

ring rolling surfaces

334, 335 of the inner ring 331 are different, and therefore, in the manufacturing process thereof, the inner tooth member 2 as a whole is subjected to the 1 st heat treatment including quenching and tempering, and thereafter, the inner

ring rolling surfaces

334, 335 of the inner ring 331 are subjected to the 2 nd heat treatment (i.e., induction quenching). Further, thereby, the hardness distribution of the internal tooth member 23 in the radial direction has the characteristics as shown in fig. 3.

The relationship between the depth from the surface of one inner ring rolling surface 334 in the inner ring 331 of the inner tooth member 23 and the vickers hardness is shown in the graph of fig. 3. The graph shows the hardness distribution of example 1 (white diamond points) and example 2 (black dots) of the internal tooth member 23 having the same manufacturing method and different sizes of the respective parts. Further, examples 1 and 2 show hardness distribution of hardness in the radial direction D from the intermediate point P in the axial direction of the one inner ring rolling surface 334 to the internal teeth of the internal gear 23g measured at intervals of 0.25mm in depth, with the axial width of one inner ring rolling surface 334 of the inner ring 331 of the internal tooth member 23 being l. However, in FIG. 3, measurement was performed at intervals of 0.5mm for a part of the region (depth 4 to 6mm, 6.5 to 7 mm).

In the graph, the horizontal axis represents the depth in the radial direction from the surface of the inner ring rolling surface 334 of the internal tooth member 23 toward the internal teeth of the internal gear 23g. On the horizontal axis, 0[ mm ] represents the surface position of the inner ring rolling surface 334 of examples 1, 2, 6.5[ mm ] represents the surface position of the internal teeth of example 2, and 7.5[ mm ] represents the surface position of the internal teeth of example 1.

The vertical axis represents hardness measured by the method of the Vickers hardness test according to JIS Z2244, and a scale of the vertical axis is 200[ HV0.3].

The internal tooth member 23 of embodiment 1 shown in fig. 3 has the following hardness distribution in order from the inner ring rolling surface 334 toward the internal teeth (straight toward the radial inside): a rolling surface hardness section H11; a rapidly decreasing portion H12 of hardness, the hardness decreasing rapidly from the rolling surface hardness portion H11; and a hardness rising portion H13 whose hardness rises and whose absolute value of the slope of the hardness change is smaller than that of the hardness change of the hardness steeply dropping portion H12.

Also, as in example 1, the internal tooth member 23 of example 2 also has the following hardness distribution in order from the inner ring rolling surface 334 toward the internal teeth: a rolling surface hardness section H21; a rapidly decreasing hardness portion H22, the hardness of which decreases rapidly from the rolling surface hardness portion H21; and a hardness rising portion H23 whose absolute value of the slope of the hardness change is smaller than that of the hardness change of the hardness rapidly decreasing portion H22. The end hardness of the hardness-raised portions H13 and H23 becomes the surface hardness of the internal teeth.

The rolling surface hardness portion H11 continues from the surface of the inner ring rolling surface 334 to the rapidly decreasing hardness portion H12, and the rolling surface hardness portion H21 continues from the surface of the inner ring rolling surface 334 to the rapidly decreasing hardness portion H22.

The rapidly decreasing portion H12 is continuous from the rolling surface hardness portion H11 to the increasing portion H13, and the rapidly decreasing portion H22 is continuous from the rolling surface hardness portion H21 to the increasing portion H23.

The hardness increasing portion H13 continues from the hardness steeply dropping portion H12 to the surface of the internal teeth of the internal gear 23g, and the hardness increasing portion H23 continues from the hardness steeply dropping portion H22 to the surface of the internal teeth of the internal gear 23g.

The rolling surface hardness portions H11 and H21 are: in the hardness distribution, a measurement point showing the surface hardness of the inner ring rolling surface 334 is set as a start point, and the hardness at each measurement point after the start point is equal to or higher than the hardness (for example, 500 HV) required for the rolling surface, and the variation in hardness is small and within a predetermined width range. The predetermined range may be set so as to be distinguishable from the rapidly decreasing portion of the hardness, but in the present embodiment, if the decrease in the hardness of the measurement point of interest with respect to the hardness of the immediately preceding (shallower 0.25mm depth) measurement point is 50HV or less, the measurement point of interest is determined to be the rolling surface hardness portion, and if the decrease in the hardness exceeds 50HV, the rapidly decreasing portion of the hardness is determined.

Fig. 3 illustrates a case where the rolling surface hardness H11 is in a range from about 0 to 2.5 mm in depth from the surface of the rolling surface 334, and the rolling surface hardness H21 is in a range from about 0 to 2.25 mm in depth from the surface of the rolling surface 334.

As described above, since the rolling surface 334 is subjected to the surface hardening treatment by induction hardening, a hardened layer composed of a hardened structure including martensite or the like as a main phase is formed in the depth range. Therefore, the rolling surface hardness portions H11 and H21 maintain a constant high hardness. The hardness of the rolling surface hardness portions H11 and H21 is in a range that satisfies the hardness required for the rolling

surfaces

334 and 335 of the inner ring 331.

The rapid hardness decreases H12 and H22 are: in the hardness distribution, the measurement point of the falling gradient of which the absolute value of the slope of the change in hardness exceeds the predetermined threshold is set as the starting point, and the range of all other measurement points after the starting point of the falling gradient of which the absolute value of the slope of the change in hardness exceeds the predetermined threshold is included. As described above, in the present embodiment, if the amount of decrease in the hardness of the measurement point of interest relative to the hardness of the previous measurement point exceeds 50HV, it is determined that the hardness decreases sharply from the previous measurement point to the measurement point of interest. However, the hardness reduction amount to be the criterion is not limited to 50HV, and may be appropriately set to a value that varies depending on the interval between measurement points or the like and that can distinguish between the rolling surface hardness portion and the hardness increasing portion and the hardness rapidly decreasing portion.

In FIG. 3, the case where the rapid hardness drop H12 is in the range of about 2.5 to 3[ mm ] from the surface of the rolling surface 334 and the rapid hardness drop H22 is in the range of about 2.25 to 2.5[ mm ] from the surface of the rolling surface 334 is illustrated.

The rapid hardness decreases H12 and H22 are depth ranges in which the change of the structure due to induction hardening does not occur, and the hardness thereof is rapidly decreased. The hardness of the sharply reduced portions H12, H22 is reduced to or slightly below the hardness required for the internal teeth of the internal gear 23g.

As described above, the rapid hardness decreasing portions H12 and H22 are ranges formed by the measurement points of the decreasing slopes in which the absolute values of the slopes of the hardness changes exceed the predetermined threshold, and thus the range in which the hardness changes can be narrowed in the radial direction. Therefore, it is easy to secure a wide radial width of the rolling surface hardness portion H11 adapted to the hardness of the rolling

surfaces

334, 335 and the hardness increasing portions H13, H23 adapted to the hardness of the internal teeth of the internal gear 23g.

The hardness increasing portions H13 and H23 are: in the hardness distribution, a measurement point at which the absolute value of the slope converted into the hardness change is equal to or less than the predetermined threshold value is set as a start point, and the absolute value of the slope of the hardness change at each measurement point after the start point is set to be equal to or less than the predetermined threshold value. In the present embodiment, even if the amount of change in the hardness of the measurement point of interest with respect to the hardness of the previous measurement point is positive (hardness increases) or negative, if the absolute value is less than 50HV, it is determined that the hardness increases from the previous measurement point to the measurement point of interest. In practice, the immediately preceding measurement point of the measurement point satisfying the condition for the first time after the rapid decrease in hardness is taken as the end point of the rapid decrease in hardness and the start point of the increase in hardness, and all the subsequent measurement points are the increase in hardness. The threshold value (50 HV) when the hardness change amount is negative is not limited to 50HV, and may be appropriately set to a value that changes according to the interval between measurement points or the like and can be distinguished from the rapidly decreasing portion of hardness. For example, in the present embodiment, the determination may be made with 100HV for a measurement point at a measurement interval of 0.5 mm. The hardness of the measurement points belonging to the hardness-raised portions H13 and H23 is preferably equal to or higher than the hardness required for the internal teeth of the internal gear 23g. The hardness of the measurement points belonging to the hardness-raised portions H13 and H23 is preferably a hardness that does not reach the hardness required for the rolling

surfaces

334 and 335 of the inner ring 331. Since the internal teeth of the internal gear 23g are formed by the gear cutting process, the workability of the gear cutting process can be improved by not increasing the hardness to be more than necessary.

In FIG. 3, the case where the hardness increasing portion H13 is in the range of about 3 to 7.5[ mm ] from the surface of the rolling surface 334 and the hardness increasing portion H23 is in the range of about 2.5 to 6.5[ mm ] from the surface of the rolling surface 334 is illustrated.

The hardness rising portions H13 and H23 locally include measurement points where the hardness change does not increase, but the hardness increases when the average value of the slopes of the hardness changes at all the measurement points of the hardness rising portions H13 and H23 is taken.

When the absolute value of the slope of the hardness change in the hardness ascending portions H13, H23 is compared with the absolute value of the slope of the hardness change in the hardness rapidly decreasing portions H12, H22, the absolute value of the slope of the hardness change in the hardness rapidly decreasing portions H12, H22 is at least 5 times, preferably 10 times or more, more preferably 15 times or more the absolute value of the slope of the hardness change in the hardness ascending portions H13, H23. Here, the slope of the hardness increasing portion (of the hardness change) means: a value obtained by dividing the amount of hardness increase from the start point to the end point of the hardness increase portion by the depth from the start point to the end point. The slope of the rapidly decreasing portion (the hardness change in) means: a value obtained by dividing the amount of hardness decrease from the start point to the end point of the rapidly decreasing portion by the depth from the start point to the end point.

The width of the depth range in the radial direction of the raised portions H13 and H23 is preferably 1 to less than 3 times the width of the depth range in the radial direction of the rolling surface hardness portions H11 and H21.

Since the hardness increases gradually in the entire portions H13 and H23, even if the hardness decreases to a value lower than the hardness required for the internal teeth of the internal gear 23g in the portions H12 and H22, the hardness increases before reaching the surface of the internal teeth of the internal gear 23g, and thus the necessary hardness requirement can be satisfied.

In the hardness increasing portions H13 and H23, the hardness is preferably increased by at least 20[ hv0.3] or more in its entirety (from the start point to the end point).

The internal tooth member 23 is entirely quenched and tempered (1 st heat treatment) to be solidified to the hardness required for the internal teeth of the internal gear 23g. In contrast, the rolling

surfaces

334, 335 of the inner ring 331 of the main bearing 33 are required to have a higher hardness.

Therefore, the rolling

surfaces

334, 335 are subjected to high-frequency quenching (the 2 nd heat treatment) as the surface hardening treatment. Accordingly, the hardness increases in a range closer to the surfaces of the rolling

surfaces

334 and 335, and the hardness required for the rolling surfaces can be satisfied. On the other hand, in the portions farther from the surfaces of the rolling

surfaces

334, 335, the heat of induction hardening transferred is lower than the temperature of the rolling

surfaces

334, 335, and thus the hardness is lowered.

In the present embodiment, the internal tooth members 23 are manufactured by a predetermined manufacturing method, so that the influence of the reduction in hardness due to induction hardening is suppressed, and the increase in hardness in the hardness-raised portions H13, H23 is achieved.

[ method of producing internal tooth Member ]

Fig. 4 (a) to 5 (C) are explanatory views showing the respective steps of the method for manufacturing the internal tooth member 23 in this order.

In manufacturing the internal tooth members 23, first, cylindrical metal pieces 23M, which are the forming material (base material) of the internal tooth members 23, are cut from a raw material (fig. 4 a: raw material cutting step).

Next, a through hole 231M for positioning or mounting in various processes is formed in the center of the metal block 23M, and chamfering processing of both axial end portions and turning processing of the V-groove 232M of the inner ring 331 (primary turning process (through hole forming process, groove forming process)) are performed.

The through hole 231M is preferably a small hole having an inner diameter sufficiently smaller than the inner diameter of the position where the inner teeth of the internal gear 23g are formed, and is preferably smaller than one third of the outer diameter of the metal block 23M, for example. Therefore, at this stage, the metal block 23M is in a state where a wall thickness is left at a position radially inward of a position where internal teeth are formed. This extra wall thickness is removed in a secondary turning process described later. The inner diameter of the through hole 231M is constant in the axial direction (except for the chamfered portion when chamfering is performed on both end portions of the through hole 231M).

Subsequently, the metal block 23M subjected to the primary turning step is quenched and tempered (heat treatment step 1).

At this time, in the 1 st heat treatment step, the metal block 23M is quenched and tempered with a wall thickness left radially inward of the position where the internal teeth are formed.

Subsequently, the V-groove 232M of the metal block 23M after the 1 st heat treatment step is subjected to induction hardening (FIG. 4B: 2 nd heat treatment step).

Next, turning is performed to form the inner peripheral surface 233M by opening the center of the metal block 23M after the 2 nd heat treatment step so as to be wider in the axial direction (fig. 4C: a secondary turning step (inner peripheral surface forming step, adjacent inner peripheral surface forming step)).

At this time, the inner teeth of the internal gear 23g in the axial direction of the inner circumferential surface 233M are turned so that the inner diameter thereof becomes smaller than the inner diameters of the adjacent inner

circumferential surfaces

234, 235 on both sides in the axial direction.

Next, turning is performed in which a cone is formed at one axial end portion of the inner peripheral surface 233M of the metal block 23M after the secondary turning step (2 nd adjacent inner peripheral surface 235) and chamfering is formed at the other axial end portion, the formation position of the internal teeth, and the like (fig. 4D: the tertiary turning step).

Next, each portion of the inner peripheral surface 233M after the turning is ground, the end surface on the other end side in the axial direction of the metal block 23M is drilled, and the bolt connection hole 23h and the bolt hole 23j are formed by taps.

Next, the internal teeth of the internal gear 23g are formed by cutting the internal teeth forming position inside the inner peripheral surface 233M of the metal block 23M after the three turning steps (fig. 5 a: internal teeth forming step).

The inner surface of the V-groove 232M on the outer peripheral surface of the metal block 23M is ground, and inner

ring rolling surfaces

334 and 335 having a target surface roughness are formed in the V-groove 232M (in fig. 5B, rolling surface forming step). Thereby, the internal tooth members 23 are produced.

The order of the steps described above with reference to (a) to (D) in fig. 4 and (a) and (B) in fig. 5 is not limited to the above order, and the order may be changed as appropriate for a step that is not significant in order. For example, the order of the internal tooth forming process and the rolling surface forming process may be replaced.

Next, the inner tooth member 23 after the rolling surface forming step is fitted inside the 2 nd housing 24 so that the rolling elements 333 are sandwiched between the inner ring 331 of the inner tooth member 23 and the outer ring 332 of the 2 nd housing 24, thereby assembling the main bearing 33 constituted of the crossed roller bearing (in fig. 5 (C): bearing assembling step).

[ technical Effect of embodiments of the invention ]

As described above, in the flexible meshing gear device 1, the internal tooth members 23 have rolling surface hardness portions H11, H21, rapidly decreasing hardness portions H12, H22, and increasing hardness portions H13, H23 in this order from the inner

ring rolling surfaces

334, 335 of the inner ring 331 toward the internal teeth of the internal gear 23g.

Therefore, even when the internal tooth members 23 are provided with the internal teeth of the internal gear 23g and the inner

ring rolling surfaces

334, 335 of the inner ring 331 having different hardness requirements, the internal tooth members 23 that accurately cope with the respective hardness requirements can be provided.

Further, since the internal tooth members 23 include the hardness rising portions H13 and H23 whose hardness rises, even if the hardness decreases to a large extent in the hardness sharply decreasing portions H12 and H22, the hardness rises in the hardness rising portions H13 and H23, so that the surface hardness of the internal tooth is easily ensured to be the required hardness.

Further, in the inner tooth member 23, since the absolute value of the slope of the rapidly decreasing portions H12, H22 is 5 times or more the absolute value of the slope of the increasing portions H13, H23, even if the rolling surface hardness portions H11, H21, which are the hardness ranges suitable for the inner

ring rolling surfaces

334, 335, and the increasing portions H13, H23, which are the hardness ranges suitable for the inner teeth, are provided, the radial width of the rapidly decreasing portions H12, H22, in which the hardness transitions between them, can be sufficiently reduced, and the rolling surface hardness portions H11, H21 and the increasing portions H13, H23 can be ensured widely.

When the inner

ring rolling surfaces

334 and 335 of the inner ring member 23 and the inner teeth of the inner ring gear 23g are arranged to overlap each other in the radial direction, the hardness distribution of the rolling surface hardness portions H11 and H21, the hardness sharply reduced portions H12 and H22, and the hardness increased portions H13 and H23 can easily optimize the hardness of the inner

ring rolling surfaces

334 and 335 and the hardness of the inner teeth of the inner ring gear 23g.

Further, in the internal tooth members 23, if the depth ranges of the hardness rising portions H13, H23 in the radial direction are set to be less than three times the depth ranges of the rolling surface hardness portions H11, H21, the external diameter of the internal tooth members 23 can be reduced.

In manufacturing the inner tooth member 23 of the flexible meshing gear device 1, the 1 st heat treatment and the 2 nd heat treatment are performed in a state where a wall thickness is left at a position radially inward of the position where the inner teeth are formed inside the metal block 23M.

Therefore, the 2 nd heat treatment (i.e., induction hardening) can be performed on the groove for forming the inner ring rolling surface in a state where the heat capacity of the metal block 23M is high. Therefore, the amount of heat transfer toward the radially inner portion than the vicinity of the surface of the groove for forming the inner ring rolling surface requiring high hardness can be reduced. This can suppress the reduction in hardness of the radially inner portion subjected to the 1 st heat treatment due to reheating by induction hardening, and can easily achieve the necessary hardness by the hardness-raised portions H13 and H23.

[ others ]

The embodiments of the present invention have been described above. However, the present invention is not limited to the above embodiments, and the details shown in the embodiments may be appropriately changed without departing from the scope of the invention.

For example, in the above-described embodiment, the so-called cylindrical structure is shown as the flex engagement gear device, but the flex engagement gear device according to the present invention is not limited to this, and may be, for example, a so-called cup type or top hat type flex engagement gear device.

The main bearing 33 is exemplified by a cross roller bearing, but is not limited thereto, and various bearings may be used, for example, a four-point contact ball bearing, a deep groove ball bearing, a roller bearing, and the like. At this time, grooves having inner ring rolling surfaces corresponding to the bearings used are provided in the inner tooth members 23.

In the above embodiment, the internal teeth of the internal gear 23g formed in the internal gear member 23 and the internal ring rolling surface 334 and the internal ring rolling surface 335 are illustrated as being arranged to overlap each other when viewed in the radial direction, but the present invention is not limited to this. That is, in the inner tooth member 23, the inner tooth and inner ring rolling surface 334 and the inner ring rolling surface 335 may be disposed so as not to overlap at all when viewed in the radial direction. At this time, as long as the same 1 st and 2 nd heat treatment steps as described above are performed on the internal tooth members, it is predicted that the hardness distribution of the reaching point on the inner circumferential surface reaching radially inward from the intermediate point in the axial direction of the inner ring rolling surface 334 or the inner ring rolling surface 335 will become the same hardness distribution as the internal teeth of the internal gear 23g. Therefore, the internal teeth of the internal gear 23g can be optimized in terms of hardness by configuring the internal tooth member 23 so that the hardness distribution ranging from the intermediate point of the inner ring rolling surface 334 or the inner ring rolling surface 335 to the reaching point includes the rolling surface hardness portion, the rapidly decreasing hardness portion, and the increasing hardness portion in this order. That is, "from the inner ring rolling surface toward the inner teeth" means: when the hardness distribution is measured straight from the inner ring rolling surface toward the radially inner side, there is also a case where the reaching point on the inner peripheral surface is not the internal teeth. At this time, the inner circumferential surface reached is assumed to be inner teeth.

In the method of manufacturing the internal tooth member 23, the example in which the through hole 231M is provided in the center of the metal block 23M in the primary turning step of the first heat treatment step 1 and the second heat treatment step 2 is shown, but the through hole 231M is not necessarily required, and the 1 st heat treatment step and the 2 nd heat treatment step may be performed on the solid metal block 23M without the through hole 231M.

The heat treatment in the 1 st and 2 nd heat treatment steps in the method for producing the internal tooth member 23 is not limited to quenching, tempering, and induction hardening, and other heat treatments that can achieve the hardness required for the inner ring rolling surface 334 and the inner ring rolling surface 335 or the internal teeth may be performed. For example, carburizing treatment or laser quenching treatment may be employed.

Further, specific conditions for the heat treatment to satisfy these hardness distributions may be determined by experiments or analysis or the like.

Claims

1. A flexible meshing gear device is provided with: a vibration starting body; an external gear deformed by the vibration starting body; an internal gear engaged with the external gear; and a main bearing for supporting the internal gear, wherein the flexible meshing gear device is characterized in that,

the internal tooth member has, in order from the inner ring rolling surface toward the internal teeth: a rolling surface hardness portion; a rapidly decreasing hardness portion from which the hardness is rapidly decreased; and a hardness rising portion, wherein the absolute value of the slope of the hardness rising and changing is smaller than the absolute value of the slope of the hardness changing of the hardness suddenly decreasing portion,

the depth range of the hardness increasing portion is smaller than 3 times of the depth range of the rolling surface hardness portion.

2. The flexible meshing gear device of claim 1, wherein,

the absolute value of the slope of the rapidly decreasing portion is 5 times or more the absolute value of the slope of the increasing portion.

3. The flexible meshing gear device according to claim 1 or 2, characterized in that,

the inner race rolling surface and the inner teeth are configured to overlap when viewed radially.

4. A method for manufacturing a flexible meshing gear device, the flexible meshing gear device comprising: a vibration starting body; an external gear deformed by the vibration starting body; an internal gear engaged with the external gear; and a main bearing for supporting the internal gear, wherein the method for manufacturing the flexible meshing gear device is characterized by comprising the following steps:

5. The method of manufacturing a flexible meshing gear device according to claim 4, further comprising a through-hole forming step of forming a through-hole in a position of the forming material radially inward of a position where the internal teeth are formed,

in the 2 nd heat treatment step, the 2 nd heat treatment is performed on the material forming the through-hole.

6. The method of manufacturing a flex spline assembly according to claim 5, wherein,

in the through-hole forming step, a through-hole having an inner diameter constant in the axial direction is formed,

the manufacturing method further includes an adjacent inner peripheral surface forming step of forming an adjacent inner peripheral surface having an inner diameter larger than an inner diameter of the internal teeth at a portion adjacent to the internal teeth in the axial direction after the 2 nd heat treatment step.