JP2001153201A - Planetary roller power transmission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent excessive load from being applied to a bearing part for rotatably supporting a planetary roller. SOLUTION: This planetary roller power transmission device is so constructed that plural first rollers 23 and second rollers 24 arranged at equal spaces in the circumferential direction between a sun roller 21 and an outer ring 22 concentrically disposed on the outer periphery side are arranged in multistage in the radial direction, and the sun roller 21 and the first rollers, and the second rollers 24 and the outer ring 22 are pressed to each other, and the first rollers 23 are rotatably held by support shafts 27 through bearings 28. In this device, when the pitch circle diameter of the support shaft 27 is taken as D, a radial clearance gap δof the bearing 28 is set to a value obtained by the expression : δ=aD0/35 (a=0.02-0.03).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planetary roller power transmission device, and more particularly to a planetary roller power transmission device such as a friction type multi-stage roller transmission in which rollers are arranged in multiple stages in a radial direction to reduce or increase input rotation. .

[0002]

2. Description of the Related Art A traction drive is a kind of friction transmission device, and power is transmitted through an oil film formed between two surfaces having a smooth surface. Therefore, operation with lower vibration and lower noise than the gear can be performed. A typical traction drive having a constant gear ratio is, for example, a planetary roller power transmission device whose main part is a schematic configuration as shown in FIG.

[0003] This power transmission device has a sun roller 1 and an outer ring 2 arranged so that their axes coincide.
And a plurality of planetary rollers 3 arranged in a pressure-contact state in a space formed between the sun roller 1 and the outer ring 2.
And a carrier 4 for rotatably holding the planetary rollers 3 at equal intervals in the circumferential direction. Such a set of planetary roller power transmission devices can set the gear ratio to 10 or more, but the contact surface pressure between the sun roller 1 and the planetary roller 3 and the outer ring 2 and the planetary roller 3
Normally, the gear ratio is 3 to 6 from the balance of the contact surface pressure
Is appropriate.

Therefore, as a power transmission device capable of obtaining a larger gear ratio, for example, FIGS. 16 (a) and 16 (b) or FIG.
There is a friction type multi-stage roller transmission as shown in FIG. This multi-stage roller transmission includes a sun roller 1 and an outer ring 2 arranged so that their axes coincide with each other, and a plurality of rollers provided in a space formed between the sun roller 1 and the outer ring 2 in a circumferential direction. In the case of two or more types of roller groups rotatably arranged at intervals, for example, in the multi-stage roller transmission shown in FIGS. 16A and 16B, each of the rollers 3a and 3b constituting two types of roller groups, and FIG. In the multi-stage roller transmission, each of the rollers is composed of three types of rollers 3a to 3c.

As will be described later, the number of each of the rollers 3a to 3c is three or more. Those rollers 3a-3c
Among them, at least one kind of roller is constituted by a plurality of cylinders, and the roller has a rolling surface of a friction contact portion having two different turning radii, so that a larger gear ratio can be secured.

That is, in the multi-stage roller transmission shown in FIGS. 16A and 16B, four first rollers 3a and four second rollers 3b are provided between the sun roller 1 and the outer ring 2 respectively. The rolling surface having two kinds of rotation radii R _1L and R _1S is formed only on the roller 3a. If rotation around the sun roller of the first roller 3a and the second roller 3b (revolution) is restrained, the speed ratio e is, e = (R _O R
The _{1L) / (R S R 1S} ). On the other hand, instead of restraining the rotation around the sun roller of the first roller 3a and the second roller 3b (revolution), in the case of restraint the rotation of the outer ring 2, the gear ratio e _{is, e = (R O R 1L} ) / (R _S R _1S)
It becomes -1.

In the multi-stage roller transmission shown in FIG. 17, five types of first to third rollers 3a to 3c are provided between the sun roller 1 and the outer ring 2, and the first roller 3a and the second roller 3b are provided. Are formed with rolling surfaces having two types of turning radii R _1L and R _1S and turning radii R _2L and R _2S respectively. First to third rollers 3a to 3c
If rotation around the sun roller of (revolution) is restrained, the speed ratio e is, e = a _{(R O R 1L R 2L)} / (R S R 1S R 2S). On the other hand, when the rotation of the outer ring 2 is restricted instead of restricting the rotation (revolution) of the first to third rollers 3a to 3c around the sun roller, the gear ratio e is e = (R
_{O R 1L R 2L) / (} R S R 1S R 2S) +1.

As described above, by increasing the number of rollers in the radial direction, a large speed ratio can be obtained without increasing the size in the axial direction.

[0009]

For example, when a rotating member is supported by a support shaft via a bearing, and the outer peripheral surface of the supporting shaft or the inner peripheral surface of the rotating member is used as a rolling surface of the bearing, the assembling property is reduced. For convenience, a small bearing clearance is generally provided in the radial direction.

For example, in the multi-stage roller transmission shown in FIGS. 16A and 16B, of the two types of roller groups provided between the sun roller 1 and the outer ring 2, each roller of one type of roller group, That is, although not shown, the second roller 3b is held by a support shaft implanted in a housing or a low-speed rotation shaft via a bearing.

FIG. 18 shows a schematic structure in which the above-mentioned second roller 3b is rotatably held by a support shaft 6 via a bearing 5 such as a needle roller bearing. In the figure, if the inner diameter of the second roller 3b, the outer diameter of the support shaft 6, and the outer diameter of the rolling element of the bearing 5 (needle roller bearing) are d _H , d _S , and d _N , respectively, the radial direction of the bearing 5 The clearance δ is δ = d _H −d _S −2
the d _N.

In normal use of the bearing 5 (needle roller bearing), an appropriate radial clearance δ is recommended according to the outer diameter d _S of the support shaft 6. For example, the outer diameter d _S of the support shaft 6 is 8
In the case of 0 mm or less, the shaft tolerance h5 and the hole tolerance G6 are recommended as the normal clearance. This is because when the outer diameter d _S of the support shaft 6 is 10 mm, the radial clearance δ of the bearing 5
Corresponds to 0.006 to 0.023 mm.

On the other hand, a hole for implanting the support shaft 6 of the second roller 3b is provided in the housing or the low-speed rotating shaft. Has become. If a radial clearance sufficient to absorb this machining error is not formed, a part of the normal force acting on each rolling surface will act on the bearing 5, and an excessive load will act on the bearing portion, and 5 may be damaged early and the bearing life is shortened. In addition, the power that can be transmitted is reduced because the normal force acting on one of the rolling surfaces decreases.

Accordingly, the present invention has been proposed in view of the above problems, and an object of the present invention is to prevent an excessive load from acting on a bearing portion that rotatably supports a planetary roller. To provide a planetary roller power transmission device.

[0015]

As a technical means for achieving the above-mentioned object, the present invention relates to a method for producing a plurality of planets in a space formed between a sun roller and an outer ring concentrically arranged on an outer peripheral side thereof. In a planetary roller power transmission device in which rollers are arranged in pressure contact at equal intervals in the circumferential direction, and each planetary roller is rotatably held by a support shaft via a bearing, when the pitch circle diameter of the support shaft is D, Let the radial clearance δ of the bearing be δ = aD ^0.35 (a = 0.02 to 0.0
It is characterized in that it is set to the value obtained in 3).

In the planetary roller power transmission device according to the present invention, the radial clearance of the bearing interposed between the planetary roller and the support shaft is made to depend not on the outer diameter of the support shaft but on the pitch circle diameter of the support shaft. To a predetermined value. By setting the radial clearance of the bearing to a value larger than the radial clearance recommended for normal use, an excessive load is prevented from acting on the bearing portion. Further, since it is not necessary to machine a hole for implanting the support shaft in a component member of the planetary roller power transmission device with an excessively high accuracy, the manufacturing cost can be reduced.

According to the present invention, two or more types of roller groups in which the planetary rollers are rotatably arranged at equal intervals in the circumferential direction are arranged in multiple stages in the radial direction in a pressed state in the radial direction. The present invention is also applicable to a multi-stage roller transmission in which each planetary roller of one type of roller group has a plurality of outer peripheral surfaces having different rotation radii.

In order to improve the life of the bearing by preventing an excessive load from acting on the bearing portion, and to provide sufficient durability with respect to the fatigue life at the rolling contact portion, the rolling surface hardness must be a certain level or more. is necessary. From this point, the rolling surface hardness of the rolling element consisting of the sun roller, the outer ring and the planetary roller is determined by the Rockwell hardness HRC.
It is desirably 58 to 65.

The rolling surface hardness of the sun roller, the outer ring and the planetary roller is defined as Rockwell hardness HRC58 or more.
In order to achieve the value of 65, the material and heat treatment of each rolling element can be realized by the following methods.
The sun roller, outer ring and planetary rollers have a carbon content of 0.95-1.10% and a chromium content of 0.90.
It is formed from high carbon chromium steel of up to 1.60%, and quenched and tempered. The sun roller, outer ring, and planetary roller are formed from medium and high carbon steel having a carbon content of 0.5% or more, and are quenched and tempered. Sun roller, outer ring and planet roller are made of case hardened steel (chrome steel,
(Chromium-molybdenum steel, nickel-chromium steel and nickel-chromium-molybdenum steel), and carburized and quenched or nitrocarburized.

As described above, as the rolling element in the planetary roller power transmission of the present invention, a high-carbon chromium steel, a medium / high-carbon steel and a case hardened steel are used.
By performing the tempering or the heat treatment of carburizing quenching or carbonitriding quenching, it is possible to secure sufficient rolling surface hardness against fatigue fracture. Further, even when metals are in contact with each other without forming a sufficient oil film in the rolling contact portion, sufficient abrasion resistance can be provided.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail.

First, the structure of the friction type multi-stage roller transmission of the embodiment shown in FIGS. 1 (a) and 1 (b) is as follows. In this multi-stage roller transmission, four types of first roller 23 and four types of second roller 24 are provided between sun roller 21 and outer ring 22, respectively.
1, a first roller 23 that comes into frictional contact with the outer peripheral surface of the sun roller 21 and the second roller 24, between a high-speed rotation shaft 25 set to 1 and an outer ring 22 coaxially arranged with the high-speed rotation shaft 25; One roller 23 and second rollers 24 that are in frictional contact with the inner peripheral surfaces of the outer ring 22 are arranged at equal circumferential intervals in pressure contact with each other.

In this embodiment, the first roller 23 has two types of rolling surfaces by being formed of a plurality of cylinders. Housing 26 for bearing and supporting the high-speed rotating shaft 25
, Four support shafts 27 are implanted, and the second roller 24 is supported by the support shaft 27 via a bearing 28 (for example, a needle roller bearing or the like), so that the second roller 24 around the sun roller is formed. The rotation (revolution) is restricted, and as a result, the rotation of the first roller 23 around the sun roller is also restricted. The outer ring 22 and the low-speed rotating shaft 29 are connected to the bolt 30 and the nut 31.
Thus, the rotation of the outer ring 22 is transmitted to the low-speed rotation shaft 29. By arranging two side plates 32 on both sides of the outer ring 22,
The axial movement of the second roller 24 is restricted.

In this embodiment, the outer ring 22 and the low-speed rotating shaft 29 are separate members, and have a structure in which both are connected by bolts 30 and nuts 31. The low-speed rotating shaft 29 and the outer ring 22 may be integrally formed so as to have a rolling contact portion that becomes a surface.

As another embodiment, the first roller 23
And rotation of the second roller 24 around the sun roller (revolution)
The structure of the friction type multi-stage roller transmission according to the embodiment in which the rotation of the outer ring 22 is restricted instead of restricting the rotation of the outer ring 22 is shown in FIG.
(A) and (b).

The multi-stage roller transmission of this embodiment is similar to that shown in FIG.
(A) As in the case of the embodiment shown in (b), four first rollers 23 and second rollers 24 are arranged between the sun roller 21 and the outer ring 22 at equal circumferential intervals in a pressed state. I have. The outer ring 22 is bolted to the housing 26 so as to be coaxial with the high-speed rotation shaft 25.
It is fixed at 0. Four support shafts 27 are implanted on the low-speed rotation shaft 29, and the second roller 24 is supported by the support shaft 27 via a bearing 28 (for example, a needle roller bearing or the like). The power is transmitted by the rotation of the sun roller 21 and the rotation (revolution) of the first roller 23 and the second roller 24 around the sun roller. The outer ring 2
By arranging two side plates 32 on both sides of 2, the axial movement of the second roller 24 is restricted.

In the multi-stage roller transmissions of the two embodiments described above, the second roller 24 is rotatably supported by the support shaft 27, so that the bearing 28 is interposed between the second roller 24 and the support shaft 27. In the above, if the pitch circle diameter of the support shaft 27 is D, the radial clearance δ of the bearing 28 is represented by δ = aD
Set to a value obtained by ^0.35 (a = 0.02 to 0.03).

In this multi-stage roller transmission, the second roller 2
The radial clearance δ of the bearing 28 interposed between the support shaft 4 and the support shaft 27 is set to a predetermined value depending not on the outer diameter of the support shaft 27 but on the pitch circle diameter D of the support shaft 27. By setting the radial clearance δ of the bearing 28 to a value larger than the radial clearance recommended for normal use, the bearing 2
8 is prevented from being applied with an excessive load.

FIG. 3 shows the effect of the clearance on the life and load capacity of the cylindrical roller bearing. The horizontal axis K represents the value obtained by dividing the clearance in the radial direction by the eccentricity of the center of the inner and outer rings in consideration of elastic deformation. It is. As is clear from the characteristics shown in the figure, the life is the longest when the preload is applied to some extent, and the life decreases as the radial clearance increases. Therefore, it is necessary to set an upper limit on the set value of the radial clearance of the bearing.

From the above points, the radial clearance δ of the bearing 28 in this multi-stage roller transmission is calculated by the above equation, that is, δ
= AD ^0.35 (a = 0.02 to 0.03). The radial clearance δ calculated by this formula is a value within the range defined by the maximum value δmax and the minimum value δmin (shaded portion in the figure) as shown in FIG. When the pitch circle diameter D = 100 mm,
As the radial clearance δ of the bearing 28, δ = 0.100
~ 0.150 is desirable.

On the other hand, in order to improve the torque transmission capacity of the traction drive, it is necessary to increase the normal load (normal force) acting on the rolling contact portion. However, the fatigue life of the rolling elements constituting the traction drive is required. Therefore, there is an upper limit on the normal force that can be applied. Therefore, regarding the fatigue life of the rolling element, with regard to the two points of the fatigue life at the place subjected to the shear force and the fatigue life at the rolling contact part,
Consider below.

First, considering the fatigue life of a portion subjected to a shearing force, as shown in FIGS. 5A and 5B, the large-diameter portion 33 of the first roller 23 formed of a cylinder having two kinds of rotation radii. Is in contact with the sun roller 21 and receives a normal force F _1, and the small diameter portion 34 of the first roller 23 is in contact with the second roller 24 and receives a normal force F ₂ . In this case, the first roller 2
Since a shearing force acts on the boundary between the large-diameter portion 33 and the small-diameter portion 34, it is necessary to impart sufficient hardness to the first roller 23 so as not to cause fatigue failure due to the shearing force.

Next, when the fatigue life at the rolling contact portion is examined, as shown in FIG.
The compressive and tensile shear stress repeatedly acts in a direction parallel to the rolling surface. As shown in FIG. 7, the shear stress acting parallel to the rolling surface becomes maximum at a depth z ₀ inside the material, and when the maximum shear stress causes fatigue fracture (flaking) starting from the inside of the material. Have been. The fatigue life at the rolling contact portion is greatly affected by the hardness. FIG. 8 shows the relationship between the hardness of the inner ring of the rolling bearing and the life. The lower the hardness is, the shorter the life is. Therefore, it is clear that sufficient hardness must be provided.

The traction drive transmits power by the shearing force of an oil film formed at the rolling contact portion. However, a sufficient oil film may not be formed depending on the state of the surface roughness and operating conditions. In that case, if the surface hardness of the members is not sufficient, they wear due to contact with each other.
In the case of a method in which the normal load for power transmission is applied by shrink-fitting, etc., if the rolling surface of the component wears, the normal load is reduced and the torque transmission capacity is reduced, but the rolling surface hardness is increased. There is a need.

Therefore, the sun roller 2 which is a rolling element
1, the rolling surface hardness of the outer ring 22, the first roller 23, and the second roller 24 is set to Rockwell hardness HRC58 or more.
65. Rolling surface hardness is Rockwell hardness HRC58
If the rolling element hardness is smaller than the above, the rolling element cannot have sufficient durability with respect to the fatigue life, and if the rolling surface hardness is larger than the Rockwell hardness HRC65, the crack sensitivity increases and the toughness decreases. It is unsuitable for dropping.

The sun roller 21 and the outer ring 22
In order to set the rolling surface hardness of the first roller 23 and the second roller 24 to Rockwell hardness HRC 58 to 65, the materials of the rolling elements and the heat treatment may be selected as follows.

First, as a first method, the sun roller 2
1. The outer ring 22, the first roller 23 and the second roller 24 are formed from high carbon chromium steel having a carbon content of 0.95 to 1.10% and a chromium content of 0.90 to 1.60%. And quenching and tempering. Figure 9 shows JIS G 4805
Shows the chemical composition of high carbon chromium steel for bearings specified in. In the table, SUJ1 is hardly used for bearings, and SUJ2 is mainly used. SUJ
3 and SUJ5 contain manganese and molybdenum in order to improve hardenability and are used for thick members. SUJ4 has a hardenability intermediate between SUJ2 and SUJ3. After cutting this high carbon chromium steel into a predetermined shape, it is hardened by heat treatment (quenching / tempering). For example, quenching heats to 800-850 ° C. and quenches into oil. Further, by performing a tempering treatment at a temperature of 150 to 180 ° C., a hardness of around Rockwell hardness HRC60 can be obtained.

Next, as a second method, the sun roller 2
1. The outer ring 22, the first roller 23, and the second roller 24 are formed from medium-high carbon steel having a carbon content of 0.5% or more, and are quenched and tempered. FIG. 10 shows the effect of the amount of carbon on the quenching hardness of the steel.
By heat-treating (quenching / tempering) 5% or more of medium and high carbon steels, the Rockwell hardness HRC 58-
A desired surface hardness of 65 is obtained.

Further, as a third method, the sun roller 21, the outer ring 22, the first roller 23, and the second roller 24 are hardened by case hardening steel (chromium steel, chromium-molybdenum steel, nickel-chromium steel and nickel-chromium steel). -Molybdenum steel) and carburized or nitrocarburized. The chemical components of each case hardened steel specified by JIS are shown in the tables of FIGS.

Chromium steel is obtained by adding about 1% of chromium to carbon steel. Among them, SCr415 and SCr
420 is used for carburizing or carbonitriding and quenching (see FIG. 11). About 1% chromium and about 0.2% in carbon steel
Chromium-molybdenum steel is obtained by adding about 0.4% of molybdenum (see FIG. 12). About 1.2 to carbon steel
The addition of 3.3% nickel and about 0.8% chromium is a nickel-chromium steel. Among them, SNC415 and SNC815 are used as case hardening steels.
(See FIG. 13). About 0.5-4.3% nickel, about 0.5-0.9% chromium and about 0.2%
% Molybdenum is nickel-chromium-molybdenum steel (see FIG. 14).

As described above, as the rolling element in the multi-stage roller transmission of the present invention, a high-carbon chromium steel, a medium-high-carbon steel or a case hardened steel is used for quenching and tempering, or carburizing and quenching or carburizing. By performing the heat treatment of nitriding and quenching, it is possible to secure sufficient rolling surface hardness against fatigue fracture. In addition, even when metals are in contact with each other without a sufficient oil film being formed at the rolling contact portion, sufficient abrasion resistance can be obtained.

In the above embodiment, a multi-stage roller transmission in which two types of rollers are arranged in multiple stages in the radial direction has been described. However, the present invention is not limited to this, and three or more types of rollers may be arranged in multiple stages. It is needless to say that the present invention can be applied to other multi-stage roller transmissions and planetary roller transmissions in which one type of roller is disposed.

[0043]

According to the present invention, the radial clearance of the bearing interposed between the planetary roller and the support shaft depends on not the outer diameter of the support shaft but the pitch circle diameter of the support shaft. By setting the value to a value larger than the radial clearance recommended for use, it is possible to prevent an excessive load from acting on the bearing portion, and to improve the life of the bearing. In addition, since it is not necessary to machine the hole for implanting the support shaft in the component member of the planetary roller power transmission device with excessively high precision, the manufacturing cost can be reduced.

[Brief description of the drawings]

FIG. 1 illustrates one embodiment of the present invention, wherein (a)
FIG. 3B is a cross-sectional view taken along the line BB in FIG.
Sectional view along line -A

FIGS. 2A and 2B show another embodiment of the present invention, in which FIG. 2A is a cross-sectional view taken along line DD of FIG. 2B, and FIG.
Sectional view along line C

FIG. 3 is a characteristic diagram showing a relationship between a life and a load capacity with respect to a value K obtained by dividing a radial clearance by an eccentricity of the center of the inner and outer rings in a cylindrical roller bearing.

FIG. 4 is a characteristic diagram showing a relationship between a radial diameter and a pitch circle diameter of a support shaft.

5A is a partial front view showing a normal force applied to a roller disposed between a sun roller and an outer ring in a multi-stage roller transmission, and FIG. 5B is a side view of FIG.

FIG. 6 is an explanatory diagram showing compressive and tensile shear stress acting in a rolling contact portion in a direction parallel to a rolling surface.

FIG. 7 is an explanatory diagram showing shear stress at a depth z ₀ and a position y ₀ .

FIG. 8 is a characteristic diagram showing a relationship between inner ring Rockwell hardness and life ratio.

Fig. 9 Table showing the chemical composition of high carbon chromium steel for bearings specified in JIS G 4805

FIG. 10 is a characteristic diagram showing a relationship between quenching hardness and carbon content of steel.

FIG. 11 is a table showing chemical components of case hardening steel (chrome steel) specified by JIS.

FIG. 12 shows case hardening steel (chrome-
Table showing chemical composition of molybdenum steel)

FIG. 13 is a table showing chemical components of case hardening steel (nickel-chromium steel) specified by JIS.

FIG. 14 is a table showing chemical components of case hardening steel (nickel-chromium-molybdenum steel) specified by JIS.

FIG. 15 is a perspective view showing a schematic configuration of a planetary roller power transmission device.

FIG. 16A is a cross-sectional view illustrating an example of a partial structure of a multi-stage roller transmission, and FIG. 16B is a cross-sectional view taken along line GG of FIG.

FIG. 17 is a cross-sectional view showing another example of a partial structure of the multi-stage roller transmission.

FIG. 18 is a schematic configuration diagram of a bearing showing a relationship among an inner diameter of a second roller, an outer diameter of a support shaft, and an outer diameter of a rolling element.

[Explanation of symbols]

 Reference Signs List 21 sun roller 22 outer ring 23 planetary roller (first roller) 24 planetary roller (second roller) 27 support shaft 28 rolling bearing

Claims (6)

[Claims] A plurality of planetary rollers are arranged at equal intervals in a circumferential direction in a press-contact state in a space formed between a sun roller and an outer ring concentrically arranged on an outer peripheral side of the sun roller. When the pitch circle diameter of the support shaft is D, the radial clearance δ of the bearing is δ = aD ^0.35 (a
= 0.02 to 0.03). 2. The method according to claim 1, wherein two or more types of roller groups in which the planetary rollers are rotatably arranged at equal intervals in the circumferential direction are arranged in a state of being pressed in multiple stages in a radial direction, and at least one type of roller among the roller groups is provided. The planetary roller power transmission of claim 1, wherein each planetary roller of the group has a plurality of outer peripheral surfaces having different radii of rotation. 3. The rolling contact surface hardness of the sun roller, outer ring and planetary roller is determined by Rockwell hardness HRC58.
The planetary roller power transmission device according to claim 1, wherein the power transmission device is set to 65. 4. The sun roller, outer ring and planetary roller are formed from a high carbon chromium steel having a carbon content of 0.95 to 1.10% and a chromium content of 0.90 to 1.60%, and quenched. The planetary roller power transmission device according to claim 3, wherein the rolling surface hardness is set to Rockwell hardness HRC 58 to 65 by tempering. 5. The sun roller, the outer ring and the planetary roller are formed of a medium or high carbon steel having a carbon content of 0.5% or more, and the rolling surface hardness thereof is quenched and tempered to change the rolling surface hardness thereof to Rockwell hardness HRC 58 or more. The planetary roller power transmission device according to claim 3, wherein the transmission is 65. 6. The sun roller, outer ring and planetary roller are formed from case hardened steel (chromium steel, chromium-molybdenum steel, nickel-chromium steel and nickel-chromium-molybdenum steel), and carburized and quenched by carbonitriding and quenching. The rolling surface hardness is defined as Rockwell hardness HR
The planetary roller power transmission device according to claim 3, wherein C58 to 65 are set.