JP2000104758A - Roller clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hardly generate a pressure flaw or a fretting abrasion on a cam surface even under a sever use condition by specifying a composition of a steel plate constituting an outer or inner ring and making a hardness higher than a predetermined value including a core portion. SOLUTION: In a roller clutch, an outer ring 2 as a member forming a cam surface 7 is constituted by applying a plastic processing to a steel plate having a composition of C: 0.5-1.1% by weight; Si: 0.01-1.0% by weight; Mn: 0.1-0.9% by weight; and remainder: Fe and unavoidable impurities. In order to form the cam surface 7, hardness of the outer ring 2 is made to Hv 650 or more including the core portion by a heat curing processing including a hardening and a tempering. Therefore, a roller 3 bits a pressure flaw portion and an abrasion portion caused on the cam surface 7 and an over-running state can not be realized. On the contrary, the roller 3 is contacted with the cam surface 7 in a state that it is not engaged with the pressure flaw portion and the abrasion concave portion and it can be prevented that a lock state can not be realized.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION A roller clutch according to the present invention comprises two members concentrically combined with each other.
When one member makes a bi-directional rotation, it is used to transmit only one of the rotations to the other member. For example, a fully automatic washing machine, a transmission, an engine accessory, etc. Used by incorporating into

[0002]

2. Description of the Related Art Roller clutches that transmit only rotational motion in a specific direction are incorporated in rotation transmission sections of various mechanical devices such as fully automatic washing machines and engine auxiliary machines, and are used.
Further, a roller clutch capable of supporting a large radial load by combining such a roller clutch and a radial rolling bearing has been widely known as described in, for example, Japanese Utility Model Laid-Open No. 3-85730. ing. 1 to 8 show six examples of such a roller clutch.

First, the roller clutch 1 of the first example shown in FIGS. 1 and 2 will be described. This roller clutch 1
It comprises an outer ring 2, a plurality of rollers 3, 3, the same number of springs 4, 4 as the respective rollers 3, 3, a retainer 5, and an inner ring 6, which is an inner member. The outer race 2 is formed in a cylindrical shape from a steel plate. When used, a holding member having a cylindrical inner peripheral surface such as a housing attached to a main body of a fully automatic washing machine or a driven pulley of an auxiliary machine for an automobile. 13 and fixed inside. The inner peripheral surface of such an outer ring 2 is a cam surface 7 which is an uneven surface extending in the circumferential direction. That is, at a plurality of locations on the inner peripheral surface of the outer ring 2, concave portions 8
Are formed at equal intervals along the axial direction of the outer ring 2 in the circumferential direction. A cylindrical gap 12 is formed between the outer peripheral surface of the inner ring 6 and the inner peripheral surface of the outer ring 2. The size of the cylindrical gap 12 depends on the diameter of the outer ring 2 (up and down in FIGS. The width dimension in the direction) is larger than the outer diameter of each of the rollers 3, 3 at a portion corresponding to each of the concave portions 8, 8, and outside of each of the rollers 3, 3 at a portion deviating from each of the concave portions 8, 8. Smaller than the diameter.

At both ends in the axial direction of the outer ring 2, flanges 9a and 9b in the form of inward flanges are formed by bending a metal plate constituting the outer ring 2 inward in the diameter direction. In addition, since one flange portion 9a is formed in advance at the time of manufacturing the outer ring 2, the thickness is equal to or greater than the cylindrical portion of the outer ring 2. On the other hand, since the other flange portion 9b is formed after incorporating the rollers 3, 3 and the retainer 5 inside the outer ring 2 in the diameter direction, the flange portion 9b is thin so that the working operation can be easily performed. Is formed.

[0005] The cage 5 constituting the roller clutch 1 is formed in a cage shape and cylindrical by injection molding synthetic resin. The retainer 5 is provided with protrusions 10, 10 formed on the outer peripheral surface inside the outer ring 2.
By engaging with the concave portions 8 formed on the inner peripheral surface of the
The outer ring 2 is mounted so as not to rotate relative thereto. The plurality of rollers 3, 3 are held inside the pockets 11, 11 formed in such a retainer 5 so as to roll and slightly displace in the circumferential direction. Each of the springs 4 and 4 has a columnar portion 15, 1, which constitutes the retainer 5 as described above.
5 and the rollers 3, 3, and the rollers 3, 3 are elastically pressed in the same direction with respect to the circumferential direction. Generally, each of the springs 4 and 4 is a stainless steel leaf spring formed by folding a band-shaped spring plate into a U-shape or a M-shape, or a synthetic resin spring formed integrally with the retainer 5. is there.

The roller clutch 1 constructed as described above is
A holding member 13 to which the outer ring 2 is fitted and fixed;
And transmits a rotational force only in a predetermined direction to a shaft (not shown) to which is fixed. For example, assuming that the outer ring 2 is fixed and only the inner ring 6 rotates in FIG. 2, when the inner ring 6 rotates clockwise in FIG. 2, each of the rollers 3 is moved from the outer peripheral surface of the inner ring 6. Based on the force received, the concave portions 8 tend to be displaced to the deeper side against the elasticity of the springs 4. Then, each of the rollers 3 becomes rotatable in the cylindrical gap 12, and the transmission of rotational force between the outer ring 2 and the inner ring 6 is stopped.
This is a so-called overrun state. On the contrary, this inner ring 6 is shown in FIG.
When rotating in the counterclockwise direction, the rollers 3, 3
Of the inner ring 6 and the respective springs 4,
4, the recesses 8, 8 bite into the shallow side in a wedge-like manner, integrally connect the outer ring 2 and the inner ring 6, and rotate between the outer ring 2 and the inner ring 6. It becomes a so-called locked state in which transmission of force can be freely performed.

In the roller clutch 1 described above, the cam surface 7 is formed on the inner peripheral surface of the outer race 2 and the outer peripheral surface of the inner race 6 is a cylindrical surface. However, the peripheral surface forming the cam surface may be reversed. . That is, like the roller clutch 1a shown in FIGS. 3 and 4 describing the structure of the second example of the conventionally known structure,
Concave portions 8a, 8a are formed on the outer peripheral surface of the inner ring 6a, which is the inner member, so that the outer peripheral surface of the inner ring 6a is a cam surface 7a and the inner peripheral surface of the outer ring 2a is a simple cylindrical surface. And
The inner ring 6a is sandwiched between a pair of spacers 14, 14 from both sides in the axial direction.

The roller clutch 1 of the first example shown in FIGS. 1 and 2 and the roller clutch 1a of the second example shown in FIGS. 3 and 4 each have a structure independent of the roller clutch. However, as shown in FIGS. 5 to 8, a roller clutch with a radial rolling bearing in which a roller clutch and a radial rolling bearing are combined has also been widely known. First, a first example of the roller clutch with a radial rolling bearing shown in FIG. 5 is a roller clutch 1 shown in FIGS.
And a pair of cylindrical roller bearings 16a and 16b. In the case of the first example, both axial ends of the inner ring 6 of the roller clutch 1 are used as inner rings of the cylindrical roller bearings 16a and 16b. Further, the second example of the roller clutch with a radial rolling bearing shown in FIG. 6 is the same as the roller clutch 1a shown in FIGS.
This is a combination of a pair of cylindrical roller bearings 16a, 16a. In the case of the second example, the roller clutch 1
a of the outer ring 2a in the axial direction with the cylindrical roller bearing 1
It is used as the outer ring of 6a and 16a. The third example of the roller clutch with a radial rolling bearing shown in FIG.
This is a combination of the roller clutch 1 shown in FIGS. 1 and 2 and a pair of ball bearings 17. Further, the fourth roller clutch with a radial rolling bearing shown in FIG.
Examples are the roller clutch 1a shown in FIGS.
This is a combination of a pair of ball bearings 17.

In any of the roller clutches 1 and 1a as shown in FIGS. 1 to 8 described above, the outer ring 2 or the inner ring 6a having the cam surfaces 7 and 7a has a C content of 0 or less. .2% or less. The reason for this is that the recesses 8, 8
This is because a is formed by plastic working. That is, the outer race 2 or the inner race 6a having the cam surfaces 7, 7a is formed by deep drawing or drawing of the low carbon steel to form the recesses 8, 8a. The surface was hardened by charcoal quenching. When the outer ring 2 or the inner ring 6a having the cam surfaces 7, 7a is manufactured in this manner, the surface hardness of the outer ring 2 or the inner ring 6a becomes Hv650 or more, but the hardness of the core becomes Hv500 or less.

[0010]

Although the conventional roller clutches 1 and 1a as described above can obtain practically sufficient reliability and durability under ordinary use conditions, the use conditions are severe. Then, the reliability or the durability is not always sufficient. That is, the meshing frequency of the roller clutches 1 and 1a increases (so that the locked state and the overrun state are frequently repeated), and the rotational speed difference between the outer wheels 2 and 2a and the inner wheels 6 and 6a in the overrun state is large. Or when the time from the overrun state to the locked state is short, and at least one of the conditions that a shocking torque is repeatedly applied at the time of locking is applied, the concave portions 8 and 8a forming the cam surfaces 7 and 7a On the basis of the pressing or rubbing of the rollers 3, 3 against the rolling surface,
One or both of indentation and fretting wear occur.

When one or both of the indentation and fretting wear occur in this way, the rollers 3, 3 remain riding on the recesses 8, 8a, and the overrun state cannot be realized, or conversely, The roller 3,
3 may not be engaged with the mouths of the recesses 8 and 8a, and the locked state may not be realized. In view of such circumstances, the present invention realizes a roller clutch in which indentations or fretting wear is less likely to occur on the recesses 8 and 8a constituting the cam surfaces 7 and 7a even under the above-mentioned severe use conditions. It is.

[0012]

A roller clutch according to the present invention is similar to the conventional roller clutch described above, for example, as shown in FIG.
As shown in FIGS. 1 to 8, outer rings 2 and 2a each having a cylindrical inner peripheral surface.
Inner ring 6, 6a having a cylindrical outer peripheral surface disposed concentrically with the outer ring 2, 2a inside the outer ring 2, 2a
Or an inner member such as a shaft, and one of the inner peripheral surface of the outer races 2 and 2a and the outer peripheral surface of the inner member, the inner peripheral surface of the outer races 2 and 2a and the outer peripheral surface of the inner member. The cam surfaces 7, 7a formed by intermittently forming concave portions 8, 8a in the circumferential direction at a plurality of places to gradually increase the thickness of the gaps in the diametric direction of the gaps between the inner member and the outer peripheral surface of the inner member. Outer ring 2, 2
a, a plurality of rollers 3, 3 inserted into a cylindrical gap 12 between the inner peripheral surface and the cam surface 7, 7a on the peripheral surface of the cylindrical gap 12; A retainer 5 which is fitted so as to be unable to rotate with respect to a certain outer ring 2 or inner ring 6a (inside member) and holds the plurality of rollers 3, 3
And springs 4, 4 provided between the retainer 5 and the rollers 3, 3 for pressing the rollers 3, 3 in the same circumferential direction.

In particular, in the roller clutch of the present invention, the outer ring 2 which is a member on which the cam surfaces 7, 7a are formed.
Alternatively, the inner race 6a (inner member) is prepared by adding C to 0.5 to 1.1% by weight (preferably 0.7 to 0.9% by weight) and Si to 0.01% by weight.
It is constituted by subjecting a steel sheet containing 0.1 to 0.9% by weight of Mn and 0.1 to 0.9% by weight of Mn to a balance of Fe and unavoidable impurities by plastic working. The hardness of the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, is Hv 650 or more including the core by hardening heat treatment including quenching and tempering. At this time, the quenching process is performed by so-called sub-hardening in which the heated steel plate is immersed in oil for the quenching process.

More preferably, one or more of the following conditions are satisfied. Outer ring 2 which is a member on which the cam surfaces 7 and 7a are formed
Alternatively, a nitriding layer or a carbonitriding layer is formed on the surface of the inner ring 6a (the inner member) on the side where the cam surfaces 7, 7a are formed. Assuming the above, the thickness of the nitriding layer or the carbonitriding layer is t, and the minimum thickness (recess 8) of the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, , 8a, t / T ≦ 0.2 is satisfied when the thickness T of the portion corresponding to the bottom portion is 0.5 to 2.0 mm. Based on the above, the ratio of N in the nitriding layer or the carbonitriding layer is set to 0.1 to 0.6% by weight, preferably 0.3 to 0.6% by weight. Outer ring 2 which is a member on which the cam surfaces 7 and 7a are formed
Or, in the steel plate constituting the inner ring 6a (the inner member), 0.3
At least one of -2.0% by weight of Cr and 0.1-1.0% by weight of Mo is contained.

[0015]

In the case of the roller clutch of the present invention configured as described above, the hardness of the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, includes the core portion.
Since Hv is 650 or more, which is higher than the hardness of the conventional core (Hv 500 or less), the indentation resistance is improved, and the reliability and durability can be improved. That is, when the rolling surfaces of the rollers 3 and 3 are strongly pressed against the surfaces of the concave portions 8 and 8a constituting the cam surfaces 7 and 7a (rolling member load is applied), the rolling member load is determined based on the rolling member load. The maximum value of the shear stress generated inside the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, becomes maximum at a predetermined depth from the surface. As before, only the surface portions of the cam surfaces 7 and 7a are
In the case of hardening by carburizing and quenching, the hardness at the portion where the above-mentioned shear stress is maximum becomes insufficient, and plastic deformation occurs at the portion, and indentations are formed on the cam surfaces 7 and 7a. On the other hand, in the case of the present invention, since the hardness of the portion where the shear stress becomes the maximum value is sufficiently high, even if the rolling element load becomes large, as is clear from FIG. Indentation is less likely to occur. That is, as is clear from FIG. 9 showing the results of an experiment conducted by the present inventor to find out the relationship between the hardness of the core and the depth of the indentation formed based on the rolling element load corresponding to the maximum rated load, If the hardness of the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, is maintained at Hv 650 or more including the core, no indentations are formed in the recesses 8, 8a. In this case, only a small (shallow) indentation that is practically acceptable is formed.

Further, nitriding or carbonitriding is performed on the surface of the outer ring 2 or the inner ring 6a (inner member) on the side where the cam surfaces 7, 7a are formed, which is the member on which the cam surfaces 7, 7a are formed. After the quenching, a quenching treatment is performed, and the surface of the cam surfaces 7 and 7a is subjected to a nitriding layer having a N content of 0.1 to 0.6% by weight, preferably 0.3 to 0.6% by weight. If a carbonitrided layer is formed and the surface hardness and the core hardness of the cam surfaces 7 and 7a are secured to Hv650 or more, FIGS.
As is clear from FIG. 1, the wear resistance of the cam surfaces 7, 7a can be improved. That is, the inventor sets the cam surfaces 7, 7
As is clear from FIG. 10, which shows the results of an experiment conducted to determine the relationship between the content of N in the nitrided layer formed on the surface of a and the amount of wear, the content of N was 0.1% by weight or more. The wear resistance is improved by setting the value to 0.3% by weight, and further improved by setting the content to 0.3% by weight or more. Further, as is apparent from FIG. 11 showing the results of an experiment conducted by the present inventor to know the relationship between the hardness of the surface of the cam surface on which the nitriding layer was formed and the amount of wear, if the hardness was set to Hv 650 or more, And wear resistance is improved.

However, when a nitriding layer or a carbonitriding layer is formed on the surfaces of the cam surfaces 7 and 7a as described above, if the minimum thickness of the cam surfaces 7 and 7a is small, the nitriding treatment is performed. The layer or the carbonitrided layer can easily reach the core.
Then, when it reaches, the strength (bending fracture strength) of the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, decreases. FIG. 12 shows the outer ring 2 or the inner ring 6a which is the member on which the cam surfaces 7, 7a are formed.
When the minimum thickness (the thickness of the portion corresponding to the bottom portions of the recesses 8 and 8a) T and the thickness t of the nitriding layer are variously changed, these values are equal to the outer ring 2 or the inner ring 6a. The results of an experiment performed by the present inventor to know the effect on the strength of the (inner member) are shown. As is apparent from FIG. 12, when the minimum thickness T of the outer ring 2 or the inner ring 6a (the inner member) is 0.5 to 2.0 mm, if the thickness is limited to t / T ≦ 0.2, the nitriding layer Can be suppressed to the extent that there is no practical problem.

Further, in the steel plate forming the outer ring 2 or the inner ring 6a (inner member), which is the member on which the cam surfaces 7, 7a are formed, 0.3 to 2.0% by weight of Cr and 0.1% When at least one of Mo and 1.0% by weight is contained, the hardenability of the steel sheet is improved, the hardness of the core is improved, and the indentation resistance can be further improved. .

Next, the reason why each of the above-mentioned elements is contained in the steel sheet for constituting the roller clutch of the present invention and the reason why the content of each of these elements is restricted to the above-described range will be described. Regarding C C is contained to harden and harden the steel sheet. If the content is less than 0.5% by weight, the hardness of the core cannot be sufficiently increased (Hv 650 or more). By containing 0.5% by weight or more, the hardness of the core is sufficiently increased (Hv 65
(0 or more). More preferably, 0.7% by weight
With the above content, the hardness of the core can be sufficiently increased (to Hv 700 or more). Conversely, when C is contained in an amount exceeding 1.1% by weight, as can be seen from FIG. 13, not only the hardness cannot be further improved, but also coarse carbides are formed inside, and The rolling fatigue life of the cam surfaces 7, 7a is reduced. Therefore, the content rate is 0.5 to
1.1 wt%, preferably 0.7 to 0.9 wt%. When the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, is formed by pressing a steel plate, the ratio of C contained in the steel plate is determined. It is preferable to keep the content to 0.9% by weight or less. The reason is that the amount of carbide present inside is kept low,
This is for improving the press workability. In order to confirm the effect when the ratio of C contained in the steel sheet is set to 0.9% by weight or less as described above, the result of an experiment conducted by the present inventors is as follows.
It is shown in Table 1 below.

[0020]

[Table 1]

In this experiment, a 120 ° bending test and a 180 ° bending test were performed on test pieces with various ratios of C contained in a steel sheet.
° Both the bending test and the number of cracks after the test were confirmed. As is evident from the experimental results shown in Table 1, if the proportion of C contained in the steel sheet is suppressed to 1.1% by weight or less, no crack is generated in the test piece in the 120 ° bending test, which is more preferable. If is controlled to 0.9% by weight or less, cracks do not occur in the test piece in both the 120 ° bending test and the 180 ° bending test, and the press workability of the steel sheet can be improved.

About Si Si is inevitably 0.0% from the oxygen scavenger used in steelmaking.
It is contained in an amount of about 1% by weight or more. Although the presence of a small amount of Si does not cause any particular problem, when the content exceeds 1.0% by weight, the cold workability of the obtained steel sheet is significantly impaired. 1.0 wt%. When the outer ring 2 or the inner ring 6a (the inner member), which is the member on which the cam surfaces 7, 7a are formed, is formed by pressing a steel plate, the ratio of Si contained in the steel plate is determined. It is preferable to suppress the content to 0.15% by weight or less. The reason for this is to suppress the reduction in press workability to a smaller extent.

Regarding Mn, Cr, and Mo All of these elements are contained in order to improve the hardenability of the steel sheet and further improve the wear resistance. Of these, Mn must be contained in an amount of 0.1% by weight or more in order to secure required hardenability.
If the content exceeds 9% by weight, the deformation resistance increases and the workability deteriorates. Therefore, the content is 0.1 to 0.9% by weight.
And In addition, Cr is contained as necessary to improve hardenability and abrasion resistance. When the content is less than 0.3% by weight, the effect of improving the hardenability and wear resistance associated with the content is hardly obtained. On the other hand, when the content exceeds 2.0% by weight, a large amount of Cr carbide is generated, and the plastic workability is reduced. Therefore, the content was set to 0.3 to 2.0% by weight. Further, Mo is contained as necessary in order to improve hardenability. When the content is less than 0.1% by weight, the effect of improving the hardenability and wear resistance associated with the content is hardly obtained. On the contrary,
If the content exceeds 1.0% by weight, no further effect can be obtained, and only the cost increases. Therefore, the content was set to 0.1 to 1.0% by weight.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A feature of the present invention is that cam surfaces 7, 7a are provided.
The composition of the steel plate forming the outer ring 2 or the inner ring 6a (the inner member), which is a member formed with the above, is devised, and the hardness of the outer ring 2 or the inner ring 6a (the inner member) is included in the Hv650 including the core.
By increasing the height as described above, the durability of the outer ring 2 or the inner ring 6a (the inner member) is improved. The specific structure of the roller clutch is the same as that of the conventionally known roller clutches 1 and 1a shown in FIGS. 1 to 8 described above, and a duplicate description will be omitted.

[0025]

Since the roller clutch of the present invention is constructed and operates as described above, even under severe use conditions,
Indentation and wear on the cam surface can be suppressed. For this reason, the roller remains biting into the indented portion or abraded portion generated on the cam surface, so that the overrun state cannot be realized, or conversely, the roller does not engage with the indented portion or the concave portion in the abraded portion. To prevent the locked state from being realized. As a result, a roller clutch having excellent reliability and durability can be realized.

[Brief description of the drawings]

FIG. 1 is a partial cross-sectional view showing a first example of a roller clutch to which the present invention is applied.

FIG. 2 is an enlarged sectional view taken on line AA of FIG. 1;

FIG. 3 is a partial sectional view showing a second example of the roller clutch to which the present invention is applied.

FIG. 4 is an enlarged sectional view taken along line BB of FIG. 3;

FIG. 5 is a partial cross-sectional view showing a first example of a structure in which a roller clutch and a radial rolling bearing according to the present invention are combined.

FIG. 6 is a partial sectional view showing the second example.

FIG. 7 is a partial sectional view showing the third example.

FIG. 8 is a partial sectional view showing the fourth example.

FIG. 9 is a diagram showing a relationship between hardness of a core portion of a member having a cam surface and indentation resistance.

FIG. 10 shows N in a nitriding layer formed on the surface of the cam surface.
FIG. 4 is a graph showing the relationship between the content of a steel and wear resistance.

FIG. 11 is a diagram showing a relationship between hardness of a surface portion of a cam surface and wear resistance.

FIG. 12 is a view showing the relationship between the minimum thickness of a member having a cam surface, the thickness of a nitriding layer, and bending strength.

FIG. 13 is a view showing the relationship between the C content and the hardness of the core.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Roller clutch 2, 2a Outer ring 3 Roller 4 Spring 5 Cage 6, 6a Inner ring 7, 7a Cam surface 8, 8a Depression 9a, 9b Flange 10 Convex part 11 Pocket 12 Cylindrical gap 13 Holding member 14 Spacer 15 Column part 16a, 16b Cylindrical roller bearing 17 Ball bearing

Claims (1)

[Claims] 1. An outer ring having a cylindrical inner peripheral surface, an inner member having a cylindrical outer peripheral surface disposed concentrically with the outer ring inside the outer ring, and an inner peripheral surface and an inner member of these outer rings. On one of the outer peripheral surfaces of the outer ring, concave portions are provided at a plurality of circumferential positions so as to gradually increase the thickness of the gap between the inner peripheral surface of the outer ring and the outer peripheral surface of the inner member in the diameter direction. A plurality of rollers inserted into a cylindrical gap between the outer peripheral surface of the inner member and the inner peripheral surface of the outer ring, and a cam surface formed by forming the plurality of rollers, A retainer that is fitted on the peripheral surface of the member having the cam surface so as to be unable to rotate and that retains the plurality of rollers, and is provided between the retainer and each of the rollers. A roller clutch with a spring that presses in the same direction around the circumference, The member on which the cam surface was formed was prepared by adding 0.5 to 1.1% by weight of C, 0.01 to 1.0% by weight of Si,
A steel sheet containing 0.1 to 0.9% by weight of Mn and the remainder Fe and unavoidable impurities is subjected to plastic working, and the hardness including the core is obtained by hardening heat treatment including quenching and tempering. A roller clutch characterized by having a Hv of 650 or more.