JP2003014067A - Rolling element for traction drive, rolling surface processing method of traction drive rolling element, and continuously variable transmission for automobile - Google Patents

Abstract

(57) [Problem] To provide a traction drive rolling element excellent in traction characteristics capable of transmitting large power. A traction drive rolling element (T1, T1) for transmitting power through traction oil between rolling surfaces.
T2, DIN 4776 measured with a surface roughness meter
Rk / Rz, which is the ratio between the effective load roughness Rk and the ten-point average roughness Rz standardized by
First machining for the rolling surface with Rvk / Ry, which is the ratio of the oil sump depth Rvk and the maximum roughness Ry, standardized in No. 6 to 0.2 or more, and formed by this first machining The second machining is performed only on the projected portion of the rolling surface,
5 larger than the traction oil film thickness on the rolling surface
Irregularities having a height difference of not more than μm are formed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power transmission device for automobiles, machine tools, etc., which is used for continuously transmitting a rotation from an input side by a traction drive and transmitting the rotation to an output side. Continuously variable transmission
Related to (continuously variable transmission for automobiles), in particular, traction drive rolling elements that transmit rotation from the input side to the output side with traction oil interposed, and traction drive rolling elements used when manufacturing the rolling elements. The present invention relates to a rolling surface processing method.

[0002]

2. Description of the Related Art The traction drive system in which power is transmitted between rolling surfaces of rolling elements via traction oil as described above has a mechanism capable of coping with a high output engine. As shown in FIG. 1, for example, a continuously variable transmission 1 for an automobile has a metallic rolling element that basically comes into contact through traction oil, that is, two discs (input shaft 2
The input disc 3 fixed to the output shaft 5 and the output disc 5 fixed to the output shaft 4, and the power roller 6 sandwiched between these discs 3 and 5, By changing the inclination and changing the contact radius of the disks 3 and 5 via the power roller 6 to change the speed, power is transmitted in a continuously variable manner. As the continuously variable transmission using the traction drive system, there are a half toroidal type continuously variable transmission and a full toroidal type continuously variable transmission.

Also in such a traction drive type continuously variable transmission, there is a demand for downsizing and an increase in transmitted power in order to meet further environmental load.

[0004]

However, in the rolling element for the traction drive (the input disc 3, the output disc 5 and the power roller 6) used in the above-mentioned conventional continuously variable transmission, the entire rolling surface thereof is used. Has been finished to a substantially uniform roughness by super-finishing, that is, no fine shape structure has been created on the rolling surface, so the power that can be transmitted was naturally limited.

That is, as long as the rolling surface does not have a fine shape structure, even if an attempt is made to increase the transmitted power by forming irregularities deeper than the oil film thickness on the rolling surface, this should be performed at a low cost. There was no proposal for a specific method of doing this.

Conventionally, as a processing method used for forming fine irregularities, for example, there is a processing method called plateau honing used for finishing the inner surface of a cylinder of an engine.

According to this plateau honing, the convex portions of the surface roughness are brought into metal contact with each other for the purpose of reducing the initial wear caused by friction with the counterpart in the cylinder, improving engine oil consumption, and retaining oil. Since the inner surface of the cylinder is finished as an allowable surface, the 10-point average roughness Rz standardized to DIN 4776 measured with a surface roughness meter is as large as about 5 to 7 μm, and the plateau surface roughness is also processed at about # 600. Therefore, it is generally a rough surface with a cross-hatch shape. Therefore, when forming unevenness deeper than the oil film thickness on the rolling surface, this plateau honing cannot be adopted. There is a problem, and it has been a conventional problem to solve this problem.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned conventional problems. In the invention according to claims 1 to 3, a rolling element for a traction drive which is capable of transmitting a large power and has excellent traction characteristics. For the purpose of providing
Further, in the inventions according to claims 4 to 12, it is possible to inexpensively create fine unevenness in which the convex portion of the surface roughness of the rolling surface does not come into metal contact with rolling of the rolling element for traction drive. It is an object of the present invention to provide a surface processing method, and further, in the invention according to claim 13, to provide a continuously variable transmission for an automobile capable of transmitting large power while realizing downsizing and cost reduction. Has an aim.

[0009]

The invention according to claim 1 of the present invention is a rolling element for a traction drive which transmits power through traction oil between rolling surfaces.
Rk, which is the ratio of the effective load roughness Rk standardized to DIN 4776 measured by a surface roughness meter and the ten-point average roughness Rz
Rvk, which is the ratio of the oil sump depth Rvk standardized by DIN4776 and / Rz is 0.1 or more, and the maximum roughness Ry.
/ Ry is 0.2 or more, the first machining is performed on the rolling surface, and the second machining is performed only on the convex portion of the rolling surface formed by the first machining, thereby rolling. It is characterized in that it has a structure in which unevenness having a height difference of 5 μm or less, which is larger than the oil film thickness of traction oil, is formed on the surface, and the structure of such a rolling element for traction drive solves the conventional problems described above. It is used as a means to

A rolling element for a traction drive according to claim 2 of the present invention is DIN47 measured by a surface roughness meter.
Effective load roughness Rk and ten-point average roughness R standardized by 76
Rk / Rz, which is the ratio with z, is 0.35 or more and DIN
The first machining for the rolling surface that makes the ratio Mr2 of the material portion to the oil sump standardized by 4776 85% or less, and the first machining only for the convex portion of the rolling surface formed by this first machining. 2. The traction drive according to claim 3 of the present invention, wherein the rolling surface is provided with the unevenness having a height difference of 2.5 μm or less, which is larger than the oil film thickness of the traction oil. The rolling element has a maximum roughness Ry of 1 to 10 μm and DIN 4776
Was formed by the first machining and the first machining on the rolling surface with Rvk / Ry, which is the ratio of the oil pool depth Rvk and the maximum roughness Ry standardized by The second machining is applied only to the convex portion of the rolling surface, and the rolling surface has a thickness of 0.5 to 5 which is larger than the oil film thickness of the traction oil.
The configuration is such that unevenness having a height difference of 2.5 μm is formed.

On the other hand, according to a fourth aspect of the present invention, there is provided a rolling surface processing method for a rolling element for a traction drive, wherein the rolling surface of the rolling element for a traction drive transmits power through traction oil between the rolling surfaces. In forming unevenness having a height difference larger than the oil film thickness of the traction oil, the ratio of the effective load roughness Rk standardized by DIN 4776 measured by a surface roughness meter and the ten-point average roughness Rz is used. In order to set a certain Rk / Rz to 0.1 or more and to set Rvk / Ry, which is the ratio of the oil pool depth Rvk standardized to DIN 4776 and the maximum roughness Ry, to 0.2 or more, the rolling elements of the traction drive should be rolled. After performing the first machining on the moving surface, the second machining is applied only to the convex portion of the rolling surface of the rolling element for traction drive formed by the first machining, and the height difference of the unevenness is obtained. And characterized in that a structure to 5μm or less, and a means for solving the conventional problems described above the configuration of the rolling surface machining method of such a traction drive rolling elements.

According to a fifth aspect of the present invention, there is provided a rolling surface processing method for a rolling element for a traction drive, which has a constitution, and an effective load roughness Rk standardized to DIN 4776 measured by a surface roughness meter and a ten-point average. Rk / Rz, which is the ratio with the roughness Rz
Is 0.35 or more and the first portion is machined on the rolling surface of the rolling element for traction drive so that the ratio Mr2 of the material portion to the oil reservoir standardized to DIN 4776 is 85% or less, Claim 2 of the present invention, wherein the second machining is applied only to the convex portion of the rolling surface of the rolling element for traction drive formed by the first mechanical machining so that the height difference of the unevenness is 2.5 μm or less. The rolling surface machining method for a rolling element for a traction drive according to No. 6 applies the first machining to a maximum roughness Ry of the rolling surface of 1 to 10 μm and the oil sump depth Rvk standardized to DIN 4776. Rvk / Ry, which is the ratio of the maximum roughness Ry to the maximum roughness Ry, is set to 0.3 or more, and the second machining is applied only to the convex portion of the rolling surface of the rolling element for traction drive formed by the first machining. The unevenness of the unevenness to 0. It is configured to be 5 to 2.5 μm.

According to a seventh aspect of the present invention, there is provided a rolling surface machining method for a rolling element for a traction drive, which is a grinding process by rotating a grindstone, or a superfinishing process in which the grindstone is relatively moved while being pressed against the rolling surface. Any one of machining, honing and lapping is the first machining, and the rolling surface machining method of the rolling element for traction drive according to claim 8 of the present invention is performed by pressing a grindstone against the rolling surface. By making the superfinishing and honing performed by relative movement the first machining, a crosshatch-shaped recess is formed on the rolling surface of the rolling element for traction drive, and the invention is defined in claim 9 of the present invention. A rolling surface processing method for a rolling element for a traction drive according to the method is a method in which a grindstone used for the first machining is an alumina-based abrasive grain having an average abrasive grain size of 20 μm or more, a SiC-based abrasive grain, BN abrasive grains and diamond abrasive grains, or an average abrasive grain diameter is 20μm or more alumina abrasive grain, SiC abrasive particles, has a configuration which is conjugates of CBN abrasive particles and diamond.

According to a tenth aspect of the present invention, there is provided a rolling surface machining method for a rolling element for a traction drive, which is a grinding process by rotating a grindstone, or a superfinishing process in which the grindstone is relatively moved while being pressed against the rolling surface. Any one of machining, honing and lapping is the second machining, and the rolling surface machining method of the rolling element for a traction drive according to claim 11 of the present invention is a grindstone used for the second machining. Alumina-based abrasive grains, SiC-based abrasive grains, CBN abrasive grains and diamond abrasive grains having an average abrasive grain size of 9 μm or less, or alumina-based abrasive grains, SiC-based abrasive grains, CBN abrasive grains having an average abrasive grain size of 9 μm or less According to a twelfth aspect of the present invention, the rolling surface processing method of the rolling element for a traction drive is the barrel machining and the second machining. It has been configured.

A continuously variable transmission for an automobile according to a thirteenth aspect of the present invention uses the rolling surface machining method for a rolling element for a traction drive according to any of the fourth to twelfth aspects to tract the rolling surface. It is characterized by having a configuration including a rolling element for a traction drive in which unevenness with a height difference larger than the oil film thickness of oil is formed, and the above-mentioned conventional problems of the configuration of such a continuously variable transmission for an automobile are described. It is a means to solve it.

In the rolling element for a traction drive and the rolling surface machining method for a rolling element for a traction drive according to the present invention, the special load curve parameter of DIN 4776 is the load curve shown in FIG. This is to evaluate the lubricity by dividing it into pooled parts.
The load length ratio 1 (initial wear load ratio) is Mr1, the load length ratio 2 (oil sump load ratio) is Mr2, the initial wear height is Rpk,
The oil sump depth Rvk and the effective load roughness are referred to as Rk, which are defined as follows.

Mr1: load length ratio 1 (initial wear load ratio) As shown in FIG. 2, a width of 40% is taken in the direction of the tp value (load length ratio) on the load curve, and the height of both ends is set. Is searched for, the intersection point a of the straight line (minimum slope line) passing through the two points and the limit line of tp = 0% is determined, and the intersection point of the horizontal line from this intersection point a and the load curve is c And t at this intersection c
The p value is Mr1 (%). This represents the load length ratio after initial wear.

Mr2: Load length ratio 2 (oil sump load ratio) Similar to Mr1, a width of 40% is taken in the direction of the tp value on the load curve, and the position where the difference in height between both ends is the minimum is set. Look for a straight line (minimum slope line) that passes through the two points and tp = 100
The intersection point b with the limit line of% is obtained, the intersection point between the horizontal line from this intersection point b and the load curve is d, and the tp value of this intersection point d is M
r2 (%). This represents the load length ratio after long term wear.

Rpk: Initial wear height The side ac is one side, and the area of a right triangle having the other side perpendicular to the one side on the limit line of tp = 0% is the 0% limit line and the side. Rp is the height on the 0% limit line that is equal to the area surrounded by ac and the load curve.
k (μm). This represents the initial wear height.

Rvk: The area of a right triangle having the oil pool depth side bd as one side and the other side perpendicular to the one side on the limit line of tp = 100% is 100% of the limit line and the side. The height on the 100% limit line that is equal to the area surrounded by bd and the load curve is Rvk (μm). This represents the depth of the sump valley.

Rk: Effective load roughness Rk (μm) is the height difference between the intersections c and d obtained above. This represents the height at which the surface wears before it becomes unusable due to long-term wear.

Ry: maximum height (maximum roughness) The maximum height obtained from the roughness curve, which is standardized to DIN4777.

Rz: 10-point average roughness DIN4768 is an average value of the maximum height differences when the measurement length is divided into five equal parts.

[0024]

In the rolling element for a traction drive according to claims 1 to 3 of the present invention, since the rolling surface has fine irregularities deeper than the oil film thickness, the power that can be transmitted becomes large. .

On the other hand, in the rolling surface machining method for a rolling element for a traction drive according to claim 4 of the present invention, since it has the above-mentioned constitution, as shown in FIG. 3, the fine groove portion D is formed by the first machining. The plateau portion P is created by flattening the convex portion by the second machining, that is, the fine groove-like concave portion formed on the rolling surface by the first machining is surely left. As a result, fine unevenness having a height difference larger than the oil film thickness of the traction oil, which cannot be achieved by plateau honing, is created on the rolling surface.

In the rolling surface machining method for a rolling element for a traction drive according to the fifth and sixth aspects of the present invention, since it has the above-mentioned constitution, the fine groove shape formed on the rolling surface by the first machining. Thus, the concave portions of are left more reliably and with a high distribution density, and stable surface quality can be obtained.

Since the rolling surface machining method for the rolling element for traction drive according to the seventh aspect of the present invention has the above-mentioned structure, a desired fine groove portion can be formed on the rolling surface quickly and inexpensively. Since the rolling surface processing method for a rolling element for a traction drive according to claim 8 of the present invention has the above-mentioned configuration, it is possible to form a groove-shaped recess having an angle of less than 90 ° with respect to the rolling direction. That means
At this time, since the recesses are almost continuously connected, the ratio of the recesses per contact surface becomes uniform,
With the rolling surface processing method for a rolling element for a traction drive according to a ninth aspect of the present invention, since the above-described configuration is adopted, the fine groove portion having a stable depth is formed.

Since the rolling surface processing method for rolling elements for traction drive according to the tenth aspect of the present invention has the above-mentioned structure, a desired plateau portion can be formed on the rolling surface quickly and inexpensively. In addition, depending on the combination of machining, the second machining can be performed by the same equipment as the first machining, and in this case, the second machining becomes cheaper, Since the rolling surface processing method for a rolling element for a traction drive according to claim 11 of the present invention has the above-mentioned configuration, the roughness of the plateau portion becomes small, and the fine groove portion and the plateau portion are clearly separated. As a result, a rolling surface capable of transmitting a large amount of power is formed, and the rolling surface machining method for a rolling element for a traction drive according to claim 12 of the present invention is configured as described above. Therefore, the plateau processing is performed on a plurality of rolling elements at the same time, which further reduces the cost of the rolling element for traction drive. For example, in the case of the first machining. Even if the shape accuracy varies, the desired plateau processing is performed stably, so that the processing quality becomes more stable.

Further, since the continuously variable transmission for an automobile according to the thirteenth aspect of the present invention has the above-mentioned structure, it is possible to transmit a large power while achieving downsizing and cost reduction as compared with the conventional one. It will be.

[0030]

Since the rolling element for traction drive according to the first to third aspects of the present invention has the above-mentioned structure, it is possible to achieve an extremely excellent effect that it is possible to increase the transmission power.

On the other hand, in the rolling surface machining method for a rolling element for a traction drive according to a fourth aspect of the present invention, since it has the above-mentioned configuration, the fine groove shape formed on the rolling surface by the first machining It is possible to make sure that the concave portions of the rolling bearings remain, and therefore it is possible to create minute irregularities on the rolling surface that have a height difference larger than the oil film thickness of traction oil that could not be achieved by plateau honing. The effect is brought.

In the rolling surface machining method for a rolling element for a traction drive according to claims 5 and 6 of the present invention, since it has the above-mentioned constitution, the fine groove shape formed on the rolling surface by the first machining. The recesses can be left more reliably and with a high distribution density, and as a result, it is possible to obtain a stable surface quality, which is a remarkably excellent effect.

In the rolling surface processing method for a rolling element for a traction drive according to a seventh aspect of the present invention, since it has the above-mentioned structure, it is possible to quickly and inexpensively form a desired fine groove portion on the rolling surface. Since the rolling surface processing method for a rolling element for a traction drive according to claim 8 of the present invention is configured as described above, it is possible to make the ratio of the recesses per contact surface uniform. In the rolling surface processing method for a rolling element for a traction drive according to Item 9, since it has the above-described configuration, a very excellent effect that a fine groove portion having a stable depth can be realized is brought about.

Since the rolling surface processing method for rolling elements for traction drive according to the tenth aspect of the present invention has the above-mentioned configuration, a desired plateau portion can be quickly and inexpensively created on the rolling surface. In addition, the second machining can be performed at a lower cost depending on the combination of machining. In the rolling surface machining method for a rolling element for a traction drive according to claim 11 of the present invention, Since it is configured, it is possible to form a rolling surface capable of transmitting a large amount of power, and the rolling surface processing method for a rolling element for a traction drive according to claim 12 of the present invention has the above-mentioned configuration. In addition to being able to further reduce the cost of rolling elements for traction drives, it has the extremely excellent effect of always stabilizing the processing quality. Is Thalassa.

Further, since the continuously variable transmission for an automobile according to claim 13 of the present invention has the above-mentioned structure, it is possible to realize a smaller size and a lower cost and to transmit a large power in comparison with the conventional one. It has a very excellent effect that it is possible to do.

[0036]

EXAMPLES A rolling element for a traction drive and a rolling surface machining method for a rolling element for a traction drive according to the present invention will be described below with reference to examples, but it goes without saying that the present invention is not limited to the following examples. Yes.

Here, a two-cylinder rolling tester 10 shown in FIG. 4 was used for rolling elements as test pieces produced by the processing methods of Examples 1 to 5 and Comparative Examples 1 and 2 below. A rolling slip test was carried out, and the traction force at that time was measured to examine whether or not there was any improvement.

As shown schematically in FIG. 4, the two-cylindrical rolling tester 10 has one rolling element T1 as a test piece.
The main shaft 11 for supporting the main shaft 11 and the slave shaft 12 for supporting the other rolling element T2 as a test piece are also provided.
The torque sensor 13 is provided in the main shaft timing belt 1 between the servo motor 14 and the motor shaft 14a.
I am crossing over 5.

The driven shaft 12 is rotatably supported by a bearing 16 fixed on a slide base B that moves in a direction orthogonal to the axial direction, and is fixed on the slide base B similarly to the main shaft 11. It is connected to the motor shaft 17a through a slave shaft timing belt 18 that is hung between the servo shaft 17a of the servo motor 17 and the slave shaft 12a by pressing the slide base B with an air cylinder 19. The rolling element T2 attached to the base B
Also, the rolling elements T1 and T2 are moved in the oil bath 20 by being moved together with the servomotor 17 so as to be brought into contact with each other to roll.

In this two-cylinder rolling test machine 10, the traction coefficient is measured by measuring the torque generated on the main shaft 11 by the torque sensor 13 provided on the main shaft 11 which is the power transmission system on the side of one rolling element T1. It can be calculated.

In this case, one rolling element T1 has a diameter of 4
0mm, thickness 20mm, traction rolling surface is R = 700mm crowning shape, J
Chrome molybdenum steel SC specified in ISG 4052
It was manufactured by grinding and superfinishing a carburized and tempered material of M420H steel. At this time, the traction rolling surface has Ra = 0.017, Ry = 0.138, Rz =
It became 0.068.

Ra represents the center line average roughness specified in JIS B 0601. As shown in FIG. 5, a reference length L is extracted from the extraction curve in the direction of the average line. When the extraction curve is represented by z = f (x) with the average line of the extracted portion as the X-axis and the direction of the vertical magnification as the Z-axis, it is defined as a value (μm) obtained by Formula 1.

[0043]

[Equation 1]

That is, in FIG. 5A, the extraction curve f
The average deviation obtained by dividing the area surrounded by (x) and the average line X-axis by the reference length L is shown.

Further, as defined in ISO 468-1982, the root mean square roughness Rq is obtained by extracting a portion of the reference length L from the extraction curve in the direction of the mean line.
The average line of this extracted portion is the X axis, and the vertical magnification direction is Z.
When the extraction curve is represented by z = f ² (x) as the axis, Equation 2
It is defined as a value (μm) obtained by

[0046]

[Equation 2]

That is, in FIG. 5B, the extraction curve f
It represents the root mean square deviation obtained by dividing the area of the portion sandwiched between the curve (x) and the mean line X-axis by the square and the area sandwiched by the mean line by the reference length L and then obtaining the square root.

The diameter of the other rolling element T2 is 40
mm, the thickness is 20 mm, the traction rolling surface has a flat cylindrical shape, and the carburizing and tempering material of the chromium molybdenum steel SCM420H steel is used in the following Examples 1 to 5 and Comparative Examples 1 and 2. By performing each processing, a large number of traction rolling surfaces having different surface fine shapes are prepared, and the other rolling element T2 obtained in Examples 1 to 5 and Comparative Examples 1 and 2 and the rolling element T1 are prepared. A rolling and sliding test was performed in combination, and the traction force and the oil film formation rate were measured.

The surface shapes of the rolling surfaces of these rolling elements T1 and T2 were measured with a stylus type roughness meter at a cutoff of 0.08 mm and a measurement length of 0.4 mm.

The test conditions by the above-mentioned two-cylinder rolling tester 10 are as follows: slip ratio: 0 to 5%, average rolling speed:
0.52 to 5.2 m / s, average shaft rotation speed (arithmetic average of the rotation speeds of the main shaft 11 and the slave shaft 12): 250 to 2500 r
pm, and the average rolling speed is kept constant by giving a differential to the main shaft 11 and the slave shaft 12 evenly.

The temperature of the traction oil in the oil bath 20 was set to 100 ° C., and the vertical load generated by the pressurizing operation of the air cylinder 19 was set to 147N. Then, the state of metal contact during operation was monitored using an electric resistance method, and the ratio of the measured potential difference and the potential difference in the completely separated state was defined as the oil film formation rate, which was used as a parameter representing the metal contact state during operation.

Next, each processing method of Examples 1 to 5 will be described.

(Example 1) In this example, aluminum oxide type abrasive grains (JIS # 120, average abrasive grain size; about 1)
(00 μm) while pressing a ceramic bond grindstone against a rotating test piece, this ceramic bond grindstone vibrates in a direction orthogonal to the direction in which the test piece rotates. Roughness with a height difference of 4.1 μm was formed on the surface.

At this time, since the abrasive grains are present on the surface of the grindstone and the protrusion amount of the abrasive grains for forming the recesses is probability distribution, the height difference of the unevenness formed on the test piece is also probability distribution. Exists in a wide range.

Therefore, in this embodiment, the effective load roughness R standardized to DIN 4776 measured by a surface roughness meter is used.
Rk / Rz, which is the ratio between k and the ten-point average roughness Rz, and Rvk / Ry, which is the ratio between the oil sump depth Rvk and the maximum roughness Ry standardized by DIN 4776, and the first machining The existence probability of the concave portion formed on the surface of the rolling surface is controlled by Rk / Rz = 0.14, Rvk / Ry =
It was set to 0.95.

Thereafter, aluminum oxide-based abrasive grains (average abrasive grain size; about 2 μm, JIS # 6) were formed on the polyester film.
000)) coated wrapping film
Lapping is performed as a second machining process in which (for example, Sumitomo 3M Co., Ltd.) is pressed against a rotating test piece, and the height difference of the unevenness of the rolling surface is set to 2.1 μm.

Since the irregularities on the surface formed by the first and second machining are irregular, the height difference between the irregularities is indicated by the maximum value.

Example 2 In this example, an aluminum oxide abrasive grain (JIS # 4) was used for a rotating test piece.
6. Grinding is performed as the first machining process in which a ceramic bond grindstone with an average abrasive grain size of about 300 μm) is rotated and cut into pieces to form irregularities with a roughness of 2.9 μm in height difference on the rolling surface. , Rk / Rz = 0.27, Rvk / Ry =
It was set to 0.24.

After that, centrifugal barrel machining as the second machining was performed to make the height difference of the irregularities of the rolling surface 2.4 μm.

(Embodiment 3) In this embodiment, similarly to the second machining in the first embodiment, the first machining with a lapping film (average abrasive grain size: about 40 μm, JIS # 400 equivalent). Lapping is performed to form unevenness with a roughness of 2.5 μm on the rolling surface, and Rk / Rz
= 0.38 and Rvk / Ry = 0.30.

After that, lapping as the second machining is performed using the same lapping film as the second machining in the first embodiment, and the height difference of the unevenness of the rolling surface is 1.
It was 5 μm.

Example 4 In this example, a ceramic bond grindstone made of cubic boron nitride (CBN) abrasive grains (JIS # 800, average abrasive grain size: about 20 μm) was pressed against a rotating test piece. , Super-finishing is performed as the first machining to vibrate this ceramic bond grindstone in the direction orthogonal to the direction in which the test piece rotates, and the unevenness of roughness with a height difference of 5.7 μm is formed on the rolling surface. , Rk / Rz
= 0.50 and Rvk / Ry = 0.23.

After that, SiC-based abrasive grains (JIS # 200
Grinding was performed as the second machining with a resin elastic whetstone having an average abrasive grain size of 0, and an average abrasive grain size of about 9 μm), and the height difference of the irregularities on the rolling surface was 2.7 μm.

Example 5 In this example, aluminum oxide type abrasive grains (JIS # 120, average abrasive grain size; about 100)
(1 μm) of ceramic bond grindstone as a first machining process for superfinishing to form roughness on the rolling surface with a roughness difference of 3.6 μm. Rk / Rz = 0.4
7, Rvk / Ry = 0.37.

Thereafter, cubic boron nitride (CBN) abrasive grains
(JIS # 4000, average abrasive grain size; about 3 μm), a super-finishing process was performed as a second machining process using a ceramic bond grindstone, and the height difference of the irregularities on the rolling surface was set to 1.1 μm.

For comparison, Comparative Example 1 corresponding to the rolling surface of the rolling element formed by the conventional processing method and Comparative Example 2 in which the processing method similar to that of the above-described embodiment is applied will be described.

Comparative Example 1 In Comparative Example 1, aluminum oxide type abrasive grains (JIS # 2000, average abrasive grain size; about 9 μm)
A super-bonding process was performed using a ceramic bond grindstone made of to obtain a surface having no plateau surface as in the above-described embodiment.

The height difference of roughness irregularities formed on the surface after processing is 0.27 μm, and Rk / Rz = 0.54, R
It was vk / Ry = 0.24.

(Comparative Example 2) In Comparative Example 2, processing was performed in the same manner as in Example 5 described above, and the distribution of the irregularities (surface shape represented by the cross-sectional curve) created by the first machining was varied. did.

Specifically, aluminum oxide type abrasive grains
(JIS # 120, average abrasive grain size; about 100 μm) Superfinishing (first machining) with a ceramic bond grindstone was performed, and the height difference of roughness irregularities formed on the surface was set to 3.8 μm, Rk / Rz = 0.32, Rvk / Ry
= 0.16.

Thereafter, cubic boron nitride (CBN) abrasive grains
(JIS # 4000, average abrasive grain size; about 3 μm) was subjected to superfinishing (second machining) using a ceramic bond grindstone, and the height difference of surface irregularities was set to 1.8 μm.

Table 1 shows the specifications of the processing methods of Examples 1 to 5 and Comparative Examples 1 and 2 described above, and Table 2 shows the measurement results of the traction force. At this time, Table 1 also shows Mr2, which is represented by the ratio of the material portion to the barry in Examples 1 to 5 and Comparative Examples 1 and 2.

[0073]

[Table 1]

[0074]

[Table 2]

The effects of the embodiment will be described based on the traction force measurement results shown in Table 2.

When Comparative Example 1 was used as a reference traction force, improvement was recognized in all of Examples 1-5.

At this time, in Examples 1 to 5, the height difference of the unevenness of the rolling surface after the second machining was 5
Although it is less than μm, since the first machining uses processing with fixed abrasives such as a grinding wheel or super-finishing wheel, a surface roughness that can be obtained reasonably without using a special wheel. As the first in the fourth embodiment
Ry5.7μ of fine groove D (see FIG. 3) obtained by machining of
As is the difference between the comparative example and the example, in the example, the traction force is improved by forming the plateau portion P (see FIG. 3). The same effect can be expected by slightly removing the convex portions on the surface obtained by the first machining.

In particular, from Examples 1 and 3 in which the improvement of the traction force was remarkable and Comparative Example 2 in which the improvement of the traction force was not observed, on the contrary, the surface after the second machining was confirmed. It is desirable that the height difference between the irregularities is 2.5 μm or less, and Rvk / Ry is desirably 0.30 or more. Then, Mr2 at this time is preferably 85% or less, and more preferably Rk / Rz is 0.35 or more.

Further, in Examples 1, 4 and 5, since the first machining was superfinishing, it was found that a cross-hatched recess was formed and good traction force was obtained.

From the traction force measurement results of each of Examples 1 to 5, the average abrasive grain size in the first machining was determined by JIS.
It was set to 20 μm or more corresponding to # 800 and the average abrasive grain size in the second machining was set to 9 μm or less corresponding to JIS # 2000, and this was set as the effective range of the present invention.

Here, it goes without saying that the same effect can be obtained even if the above-mentioned abrasive grains are those other than the types shown in Examples 1 to 5.

The super-finishing processing shown in the above embodiment is treated as a synonym for honing processing depending on the cutting speed and processing state.

[Brief description of drawings]

FIG. 1 is an explanatory cross-sectional view showing a basic configuration of a continuously variable transmission for an automobile.

FIG. 2 is an explanatory diagram showing definitions of an oil sump depth Rvk and an effective load roughness Rk in a special load curve parameter described in DIN4776.

FIG. 3 is a model explanatory view showing an outline of surface processing according to the present invention.

FIG. 4 is a schematic explanatory view of a two-cylinder rolling tester that performs a rolling slip test on a rolling element for traction drive formed by the rolling surface processing method for a rolling element for traction drive according to the present invention.

FIG. 5 is an explanatory view (a) showing a definition of a centerline average roughness Ra for evaluating a traction force and an explanatory view (b) similarly showing a definition of a root mean square roughness Rq for evaluating a traction force. ).

[Explanation of symbols]

1 Continuously variable transmission for automobiles 3 input disk 5 output discs 6 power rollers T1, T2 rolling element for traction drive

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsuomi Nakayama             Nissan, Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan             Inside the automobile corporation F-term (reference) 3C049 AA03 AA09 CA01 CA03                 3J051 AA03 BA03 BB02 BD02 BE09                       CA05 CB07 EC07 FA02 FA07

Claims (13)

[Claims] 1. A rolling element for a traction drive that transmits power through traction oil between rolling surfaces, the effective load roughness Rk and DIN standardized to DIN 4776 measured by a surface roughness meter. Rk / Rz, which is the ratio to the point average roughness Rz, is 0.1 or more, and R, which is the ratio of the oil sump depth Rvk standardized to DIN 4776 and the maximum roughness Ry.
The first machining is performed on the rolling surface having vk / Ry of 0.2 or more, and the second machining is performed only on the convex portion of the rolling surface formed by the first machining, and the rolling is performed. A rolling element for a traction drive, characterized in that unevenness having a height difference of 5 μm or less, which is larger than an oil film thickness of the traction oil, is formed on the moving surface. 2. DIN 4776 measured with a surface roughness meter
Rk / Rz, which is the ratio between the effective load roughness Rk and the ten-point average roughness Rz standardized by
Ratio of material part to oil sump standardized by 76 Mr
2 is 85% or less, the first machining for the rolling surface and the second machining only for the convex portion of the rolling surface formed by this first machining are applied to the rolling surface. The rolling element for a traction drive according to claim 1, wherein irregularities having a height difference of 2.5 μm or less, which is larger than an oil film thickness of the traction oil, are formed. 3. A rolling surface having a maximum roughness Ry of 1 to 10 μm and a ratio Rvk / Ry of the oil reservoir depth Rvk standardized to DIN 4776 and the maximum roughness Ry of 0.3 or more. And the second machining is applied only to the convex portion of the rolling surface formed by the first machining, and the rolling surface has a thickness larger than the oil film thickness of the traction oil of 0.5. The rolling element for a traction drive according to claim 2, wherein irregularities having a height difference of about 2.5 μm are formed. 4. A surface for forming unevenness having a height difference larger than the oil film thickness of the traction oil on the rolling surface of the rolling element for traction drive that transmits power through the traction oil between the rolling surfaces. DIN 4776 standardized effective load roughness Rk measured with a roughness meter
And Rk / Rz, which is the ratio of the ten-point average roughness Rz, is 0.1 or more and the oil sump depth Rv standardized to DIN 4776.
After performing the first machining on the rolling surface of the rolling element for traction drive so that Rvk / Ry, which is the ratio of k to the maximum roughness Ry, is 0.2 or more, the first machining is performed. A method for processing a rolling surface of a rolling element for a traction drive, characterized in that the second machining is applied only to the convex portion of the rolling surface of the formed rolling element for a traction drive so that the height difference of the unevenness is 5 μm or less. . 5. DIN 4776 measured with a surface roughness meter
Rk / Rz, which is the ratio between the effective load roughness Rk and the ten-point average roughness Rz standardized by
Ratio of material part to oil sump standardized by 76 Mr
After the first machining is performed on the rolling surface of the rolling element for traction drive so that 2 is 85% or less, the projection of the rolling surface of the rolling element for traction drive formed by the first machining The rolling surface machining method of the rolling element for traction drive according to claim 4, wherein the height difference of the unevenness is 2.5 μm or less by subjecting only the portion to the second machining. 6. A first machining process is performed to set the maximum roughness Ry of the rolling surface to 1 to 10 μm, and Rvk, which is the ratio of the oil sump depth Rvk standardized to DIN 4776 and the maximum roughness Ry. / Ry is set to 0.3 or more, and the second machining is applied only to the convex portion of the rolling surface of the traction drive rolling element formed by the first machining so that the height difference of the concavities and convexities is 0.5 to
The rolling surface machining method for a rolling element for a traction drive according to claim 5, wherein the rolling surface is 2.5 μm. 7. The first machining is a grinding process performed by rotating a grindstone, or a superfinishing process, a honing process, or a lapping process performed by relatively moving the grindstone while pressing it against a rolling surface. Item 7. A rolling surface machining method for a rolling element for a traction drive according to any one of Items 4 to 6. 8. A crosshatch-shaped recess is formed on the rolling surface of the rolling element for traction drive by using superfinishing or honing, which is performed by relatively moving the grindstone while pressing it against the rolling surface, as the first machining. 4. Forming
A rolling surface machining method for a rolling element for a traction drive according to any one of 1. 9. A grindstone used for the first machining is made of alumina-based abrasive grains, SiC-based abrasive grains, C having an average abrasive grain size of 20 μm or more.
BN abrasive grains and diamond abrasive grains, or alumina-based abrasive grains, SiC-based abrasive grains, C having an average abrasive grain size of 20 μm or more.
The rolling surface processing method for a rolling element for a traction drive according to claim 7 or 8, which is a combination of BN abrasive grains and diamond. 10. The second machining is any one of a grinding process performed by rotating a grindstone, or a superfinishing process performed by relatively moving the grindstone while pressing the grindstone against a rolling surface, a honing process and a lapping process. Item 10. A rolling surface machining method for a rolling element for a traction drive according to any one of items 4 to 9. 11. A grindstone used for the second machining is made of alumina-based abrasive grains, SiC-based abrasive grains, C having an average abrasive grain size of 9 μm or less.
BN abrasive grains and diamond abrasive grains, or alumina-based abrasive grains, SiC-based abrasive grains, CB having an average abrasive grain size of 9 μm or less
The rolling surface processing method for a rolling element for a traction drive according to claim 10, which is a combination of N abrasive grains and diamond. 12. The rolling surface machining method for a rolling element for a traction drive according to claim 4, wherein barrel machining is second machining. 13. A traction in which unevenness having a height difference larger than an oil film thickness of traction oil is formed on a rolling surface by the rolling surface processing method for a rolling element for a traction drive according to any one of claims 4 to 12. A continuously variable transmission for an automobile, which is provided with a rolling element for a drive.