JP2000120835A - Differential gear and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a differential gear and manufacture thereof in which a meandering continuous groove provided on the facing surface of a disc plate is formed precisely and which can improve the surface roughness and transmit the torque stably and manufacture at a low cost. SOLUTION: This is a differential gear in which a processed disc plate 2 having formed a meandering continuous groove having left a rolling allowance advancely, balls 9 for rolling, a holder 5 for holding this ball 9 for rolling by a long hole extending to the diameter direction, a disc plate 1 for die facing to the processed disc plate coaxially and also forming the guide groove of the ball 9 for rolling and the push-press means of the ball 9 for rolling to the processed disc plate 2 are prepared, and having the disc plate manufactured by a rolling method by rotating either one of the disc plate 1 for die or processed disc plate 2. The shape error of the rolling surface of the meandering continuous groove is 100 μm or less and its roughness Rz is 10 μm or less.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention enables a difference in rotation between left and right drive wheels and front and rear drive shafts of an automobile, and generates a differential limiting torque when one of the drive wheels or the drive shaft idles. The present invention relates to a differential device capable of increasing a driving force and a manufacturing method thereof.

[0002]

2. Description of the Related Art An automobile differential device is a device that enables a difference in rotation between left and right drive wheels and a difference in rotation between front and rear drive wheels when a vehicle curves (in the case of a four-wheel drive vehicle). Conventionally, as a vehicle differential having such a function, a pinion gear is interposed between a pair of bevel gears connected to an output shaft, and when a rotational force is applied to the shaft of the pinion gear from the outside, the differential is performed. At times, a pinion gear is rotated on its own to make a difference in rotation between output shafts widely used.

However, when one of the driving wheels falls into snow or sand, or falls into a groove or the like, one of the wheels runs idle due to the differential and the entire driving force is lost, so that it is impossible to escape. Many. In addition, when the load on the inner wheels is extremely reduced even when the vehicle turns, the wheels may spin and the driving force for traveling at high speed on the curve may be lost.

[0004] As a differential device which has solved such a problem, there has been proposed a differential device having, for example, a clutch disk crimping type differential limiting mechanism. This is because a preload is applied to the clutch disc in order to obtain a driving force even when one of the driving wheels is not in contact with the ground, so that each driving wheel is restrained even when the driving force is not applied from the engine side. ,
There was a difficulty in combination with a device that requires independence in rotation of each wheel, such as an anti-lock brake system.

A differential having a viscous coupling type torque-sensitive differential limiting device has also been proposed and used. The viscous coupling transmits torque using the shear resistance of a viscous fluid (such as silicon oil), and can provide a smooth differential limiting effect according to the rotation difference of the drive wheels. However, since the initial resistance is given by the viscous fluid, there is still a problem that each driving wheel is restricted.

In view of such circumstances, Japanese Patent Laid-Open Publication No. Hei 8-170705 has proposed a differential device which is smaller than the differential device and has a differential limiting function without adding a special mechanism.

This differential device comprises (a) a pair of rotating bodies fixed to driving wheels and arranged coaxially so as to face each other in the axial direction. A disk plate on which a circumferential continuous groove meandering so as to fluctuate in the direction position (hereinafter referred to as a meandering continuous groove); and (b) disposed between a pair of disk plates and extending in a radial direction. (C) rolling along a meandering continuous groove of a pair of opposed disk plates, and reciprocating radially one by one in each guide groove. A ball housed movably, (d) a case body rotatably housing the disc plate and a ball case fixedly housed therein, and (e) a case body contacting the outer surface of each disc plate. It has and a deployed thrust washer.

In this differential device, when the ball moves in the meandering continuous groove in the circumferential direction, the ball reciprocates in the guide groove of the ball holder in the radial direction, and the driving force from the engine is transmitted through each disk plate. As a result, when a rotational difference occurs between the drive wheels, a differential is enabled. If one of the drive wheels idles, the thrust force generated on the disk plate connected to that drive wheel generates a sliding friction force between the outer surface of the disk plate and the thrust washer, thereby reducing the differential limiting effect. You can get it.

FIG. 5 shows an example of a differential device disclosed in Japanese Patent Application Laid-Open No. 8-170705, FIG. 6 is an exploded sectional view thereof, and FIG. 7 shows a combination of one disk plate, a ball holder and a ball. Indicates the status. As shown in FIG. 5, a differential device disclosed in Japanese Patent Application Laid-Open No. 8-170705 has a case 1 having an open end at one end and a coaxial annular projection 101 at the other end.
0, a case cover 20 having an opening end having the same size as the opening end of the case 10 and having a coaxial annular projection 201 at the other end, and a pair of disk plates 3 arranged coaxially and opposed to each other. , 4, a ball holder 5 disposed between the pair of disc plates 3, 4, a plurality of balls 6 rotatably held by the ball holder 5, and a pair of balls located outside the disc plates 3, 4. Thrust washers 7 and 8 are provided.

(1) Case (Input-side Disk Plate) The coaxial annular projection 101 of the case 10 acts as a bearing for rotatably supporting one disk plate 3. A groove 102 is formed on the inner wall of the case 10 so as to engage with the outer peripheral projection 52 of the ball holder 5.
The ball holder 5 is locked to the case 1 by a plurality of locking members 10 interposed between the outer circumferential portion of the ball holder 5 and the inner wall of the case 10 by the engagement of the outer protrusion 2 with the outer circumferential projection 52. Case 1
A plurality of holes 104 are provided on the side wall of the case 10 so that lubricating oil can flow into the case 10. Numerous holes 105a for bolt insertion are provided in the flange 105 provided at the open end of the case 10.

(2) Case Cover The case cover 20 has a shallow dish shape, and its coaxial annular projection 201 functions as a bearing for rotatably supporting the other disk plate 4. In addition, case cover 2
A plurality of holes 204 for lubricating oil inflow are provided in the side wall 0. The flange portion 205 provided at the opening of the case cover 20 is provided with a large number of holes 205a at positions corresponding to the holes 105a of the case 10, and bolts penetrating both holes 105a, 205a (FIG. (Not shown), the case 10 and the case cover 20 are fixed.

(3) Disk Plate As shown in FIG. 7, circumferentially continuous grooves 31 and 41 meandering in such a manner that the position in the radial direction fluctuates at regular intervals are formed on the opposing surfaces of the disk plates 3 and 4. Are formed.
The meandering continuous grooves of the disk plates 3 and 4 extend in the same direction in the reverse rotation direction, and have an arc-shaped or V-shaped cross section so that the ball 6 can rollably engage. At the other end of each of the disk plates 3 and 4, there are provided annular projections 32 and 42 for connecting a drive shaft (not shown), and on the inner surfaces of the annular projections 32 and 42, an axis for fixing the drive shaft is provided. Direction grooves 32a and 42a are provided.

(4) Ball Holder The ball holder 5 is provided with a number of elongated guide holes 51 having a width enough to receive the ball 6 and allowing the ball 6 to reciprocate in the radial direction. The radial length of the guide hole 51 that defines the range of reciprocation of the ball 6 is determined by the radial upper limit position (the position farthest from the center) and the radial lower limit position (the position closest to the center) of each of the continuous meandering grooves 31 and 41.
Equal to the difference between

(5) Thrust washers Thrust washers 7 and 8 are arranged between the case 10 and the disk plate 3 and between the case cover 20 and the disk plate 4, respectively. Is in sliding contact. Both drive wheels (not shown)
When there is no difference in rotation or when one of the driving wheels is not idling, no thrust force is applied to the disc plate 3 or 4, so that the disc plates 3 and 4 and the thrust washers 7 and 8 Has substantially no frictional force.

The operation of the differential will be described with reference to FIGS. FIG. 9 is an enlarged view showing one unit section of the meandering continuous groove 31 of the disk plate 3, and FIG. 10 is a radial distance R (the center of the disk plate 3 and the meandering continuous groove 31) at the rotation angle θ of the meandering continuous groove 31. Distance). The relationship between the meandering continuous groove of the other disk plate 4 and the guide hole 51 of the ball 6 and the ball holder 5 is exactly the same.

The meandering continuous groove 31 has a first guide section 31 a extending the ball 6 from the radially outer side to the inner side of the disk plate 3 and a second guide section 31 extending the ball 6 from the radially inner side to the outer side of the disk plate 3. Guidance section 31
b and a third guide section 31c for keeping the ball 6 at a constant position in the radial direction of the disk plate 3, a plurality of unit sections are continuous in the circumferential direction. In the case of the embodiment shown in FIGS. 8 to 10, the rotation angle θ of each unit section is 72 °,
There are five unit sections in one round.

Similarly, a first guide section 41a and a second guide section 41 extending the ball 6 from the radially inner side to the outer side of the disk plate 4 are provided on the other disk plate 4.
A plurality of unit sections consisting of b and a third guide section 41c for keeping the ball 6 at a constant position in the radial direction of the disc plate 4 are continuous in the circumferential direction.

Since the meandering continuous groove 31 of the disk plate 3 and the meandering continuous groove 41 of the disk plate 4 have a mirror image relationship with respect to the radius (for example, the radius OP in FIG. 7) passing through the end of each unit section, the ball 6 It follows the same trajectory in the reverse rotation direction. The state where both disc plates 3 and 4 are combined with the ball holder 5 is as shown in FIG. For this reason, the ball 6 is formed in the meandering continuous groove 3 of the disc plate 3.
1 moves in the direction of arrow R (clockwise) in the meandering continuous groove 41 of the disc plate 4 at the same time along the same trajectory in the direction of arrow (counterclockwise). I have.

Therefore, if one of the disk plates 3 is rotated with the ball holder 5 fixed, the other disk plate 4 rotates in the opposite direction at the same speed. In this case, when the ball 6 moves in the meandering continuous grooves 31 and 41 by a rotation angle of 72 ° (that is, moves in the unit section), the ball 6 reciprocates once in the guide hole 51 of the ball holder 5 in the radial direction.

The shape of the two meandering continuous grooves 31 and 41 and the movement of the ball 6 will be examined in more detail. When the ball 6 is in the radial reversal position (the position at which the radial distance from the center of the disk plate 3 changes from increasing to decreasing or decreasing to increasing) and in the third guide section 31C, the ball 6 and the meandering continuous groove 3
1 is not transmitted, but in other sections, the force is transmitted to the arcuate inner wall of the meandering continuous groove 31. The meandering shape of the meandering continuous groove 31 is a ≦ a ′, b ≧ b ′, c ≦ c ′, d
= D ', the sections 31a and 31
When any one of the two balls 6 in b is in a position that does not transmit force, the other ball 6 is always in a position that transmits force.

In the meandering continuous groove 31, sections a, e, f,
In sections other than 31c, g and h, the ball 6 meanders so that the axial component (thrust force) of the ball 6 with respect to the disk plate 3 changes in proportion to the magnitude of the rotational torque applied to the case 10. The angle of contact with the continuous groove 31 changes. Therefore, the differential limiting torque due to the friction between the thrust washers 7 and 8 is proportional to the rotation torque applied to the case 10. The above theory can be applied as it is even when the rotation angle of the unit section of the meandering continuous groove 31 is other than 72 °.

[0022]

FIG. 11 shows a cross-sectional shape of a meandering continuous groove 31 provided in the disk plate 3. The meandering continuous groove 31 is formed in an arc-shaped concave curved surface having a radius R substantially the same as that of the ball 6, and holds the ball 6 in contact with the meandering continuous groove 31 and movably in the meandering continuous groove 31. I have. By making the shape of the meandering continuous groove 31 highly accurate, the balls 6 held in the meandering continuous groove 31
Can transmit torque to the disk plates 3 and 4 without being shaken even during high-speed rotation.

The arc-shaped concave curved surface of the meandering continuous groove 31 is shown in FIG.
2, and is processed by a special end mill 61 having an arc-shaped cutting edge 62 having a radius R. However, an accurate circular curved surface cannot be formed by a single cutting. After performing primary processing to form a rough continuous meandering groove, cutting is performed several times, and the accuracy and surface roughness are gradually increased. Secondary processing is necessary, and there is a problem that the processing time is long. In addition, special end mills are not only expensive, but also the cost of regrinding is higher than ordinary tools. Therefore, the manufacturing cost of the differential device increases.

An object of the present invention is to provide a differential device which can stably transmit torque by improving the surface roughness of a groove provided on a facing surface of a disk plate, and can be manufactured at low cost. And a method for producing the same.

[0025]

As a result of intensive studies in view of the above-mentioned problems, the present inventors have found that a mold disk plate having a meandering continuous groove, a ball holder, and a rolling ball are used to form a ball holder. A mold disc plate with a ball incorporated at one end of the guide hole, with both sides facing each other,
The meandering continuous groove is sandwiched between the preformed work disk plate, the mold disk plate is fixed immovably, and the ball holder is rotated while the work disk plate is held rotatably to meander the rolling balls. By forcibly moving along the continuous groove, the arc-shaped concave curved surface of the meandering continuous groove can be rolled with high accuracy and improved surface roughness by the pressure of the ball,
The present invention has been completed based on the finding that it can be manufactured at low cost.

That is, the differential device according to the present invention comprises an input-side rotating body that rotates by an external driving force, a pair of disk plates opposed to each other and arranged coaxially with the input-side rotating body, A plurality of balls disposed between opposing surfaces of the disk plate; and a holder that holds each ball and rotates integrally with the input-side rotator, wherein the holder extends in a radial direction of each disk plate. It has multiple slots,
A differential device in which each ball is movably housed in each elongated hole, and a meandering continuous groove in which each ball is rotatably engaged is provided on an opposing surface of each disk plate; Is characterized in that the meandering continuous groove provided on the opposing surface for transmitting force is assembled as a rolling surface having a shape error of 100 μm or less and a surface roughness (Rz) of 10 μm or less.

Further, according to the present invention, there is provided a method of manufacturing a differential device, comprising: an input-side rotating body rotating by an external driving force; and a pair of disk plates opposed to each other and arranged coaxially with the input-side rotating body. A plurality of balls arranged between opposing surfaces of the respective disc plates, and a holder that holds the respective balls and rotates integrally with the input-side rotator, wherein the holders are arranged in a radial direction of the respective disc plates. A plurality of long holes extending in a longitudinal direction, each of the balls is movably accommodated in each of the long holes, and a meandering continuous groove is provided on the opposing surface of each of the disk plates so that each of the balls can roll freely. A method of manufacturing a moving device, wherein a meandering continuous groove provided on an opposite surface of the disk plate is formed by moving while rolling a rolling ball.

The meandering continuous grooves provided on the opposing surface of the disk plate include: (1) a disk plate to be processed in which a groove having a rolling allowance is formed in advance; (2) a rolling ball; (4) a mold disk plate which coaxially opposes the disk plate to be processed and has a guide groove for the rolling ball, and (5) Preparing means for pressing the rolling ball against the work disk plate, and rotating one of the mold disk plate and the work disk plate to rotate the ball by the rolling ball. It can be manufactured by rolling grooves of a disk plate to be processed.

The rolling allowance is preferably 0.02 to 0.2 mm, and the radius of the rolling ball is preferably +0.0 to 0.2 mm of the radius of the ball used in the differential device. Rolling makes a low cost differential

[0030]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A disk plate used in a differential gear according to the present invention has the same manufacturing method as a conventional one except for a secondary working for forming an arc-shaped concave curved surface in a meandering continuous groove. Only processing will be described.

[1] Apparatus for Manufacturing Disc Plate The apparatus for manufacturing a disc plate includes a mold disc plate 1 shown in FIG. 1, a work disc plate 2, a ball holder 5, and a roll which is inserted into a guide hole 51 of the ball holder. Means (not shown) for fixing the forming disc 9 and the mold disc plate 1;
And a means (not shown) for rotating the ball holder 5. A meandering continuous groove 11 for determining the movement of the ball is provided on the disk surface of the mold disk plate 1 as shown in FIG. On the other hand, the meandering continuous groove 2 of the same shape formed while leaving a rolling allowance is formed on the disk surface of the disk plate 2 to be processed.
1 is preformed.

At the time of manufacture, the mold disk plate 1
With the disk surface facing the disk plate 2 to be processed, the ball holder 5 in which the rolling ball 9 is inserted into one end of the guide hole 51 is sandwiched between the disks 1 and 2, and the meandering continuous groove on each disk plate The ball holder 5 is held coaxially by holding the rolling ball 9 between 11 and 21,
By rotating the ball holder 5, the rolling ball 9 is forcibly moved along the meandering continuous grooves 11 and 21. Rolled ball 9
Is rolled into the meandering continuous groove 21 on the disk 2 to be processed.

(1) Mold Disc Plate The meandering continuous groove 1 is formed on the disc surface of the mold disc plate 1.
1 is provided, and the other end is provided with a protrusion 12 for fixing to a rolling device. The mold disk plate 1 has a precise meandering continuous groove 2
To form one. It is used to guide the movement of the rolling ball 9. Therefore, the meandering continuous groove 11 is substantially the same as the meandering continuous groove 31 shown in FIG.
However, the radius of the arc-shaped concave curved surface of the meandering continuous groove 31 is set to be substantially the same as the radius of the rolling ball 9.

The material of the molding disc plate 1 can be selected as appropriate, but is made of a material having a hardness at least equivalent to that of the rolling ball 9.

(2) Disk Plate to be Processed The disk plate 2 to be processed is a semi-finished product of the disk plate to be actually manufactured. The disk surface is provided with a meandering continuous groove 21 formed leaving a rolling allowance. ing.

As shown in FIG. 2, the cross section of the meandering continuous groove 21 which has been subjected to the primary processing may be V-shaped (FIG. 2 (a)) or U-shaped (FIG. 2 (b)). Preferred in U-shape. The cross-sectional dimension of the meandering continuous groove 21 is the actual required dimension (FIG. 2).
(Dotted line in the middle) smaller than the rolling allowance. Rolling allowance is 0.02
~ 0.2 mm is preferred. When the rolling allowance is less than 0.02 mm, it is difficult to uniformly roll the meandering continuous groove 21. On the other hand, when the rolling allowance exceeds 0.2 mm, the resistance at the time of rolling becomes too large, and a precise concave surface cannot be formed.
A preferable rolling allowance is 0.03 to 0.1 mm.

FIG. 3 is a sectional development view of the meandering continuous groove 21 in the traveling direction. At least one concave portion 22 is provided in the meandering continuous groove 21. The concave portion 22 is for holding the rolling ball 9 at a desired depth (indicated by a dotted line 23) at the start of rolling. The concave portion 22 needs at least the number of rolling balls 9 to be used. The shape of the concave portion 22 is not particularly limited, and the rolling ball 9 is formed at a desired depth (dotted line 23).
) May be V-shaped (FIG. 3A) or U-shaped (FIG. 3B).

(3) Rolling Ball The radius of the rolling ball 9 is the same as or slightly larger than the ball 6 used in an actual differential. A preferable radius of the rolling ball 9 is R to R, where R is the radius of the ball 6.
R + 0.2 mm. The number of the rolling balls 9 used in one rolling may be one, but it is preferable to use a plurality of the rolling balls 9 for balancing.

The rolling ball 9 is used for deforming the work disk plate 2 to roll the cross section of the meandering continuous groove 21 into an arc shape, and is preferably made of a material harder than the work disk plate 2. . As such a material,
Bearing steel and the like can be mentioned, but can be appropriately selected depending on the material of the disk plate 2 to be processed.

(4) Ball Holder The ball holder 5 has an elongated guide hole 51 having a width enough to receive the rolling ball 9 and allowing the rolling ball 9 to reciprocate in the radial direction. Are provided. The radial length of the guide hole 51 that defines the range of reciprocation of the rolling ball 9 is determined by the radial upper limit position (the position farthest from the center) and the radial lower limit position (from the center) of each of the meandering continuous grooves 11 and 21. The closest position). Although the ball holder 5 may have the same shape as that of the actual differential shown in FIG. 7B, the size of the guide hole 51 needs to be substantially the same as the rolling ball 9.

Although the present invention has been described with reference to actual examples, the present invention is not limited thereto, and various changes can be made without departing from the gist of the present invention. For example, the number of guide holes 51 of the ball holder 5 does not necessarily need to be the same as the number of ball holders of the differential device, but may be any number as long as the number of rolling balls 9 used at one time.

[2] Manufacturing Method First, as shown in FIG.
A rolling ball 9 is incorporated in the mold 1 and both sides thereof are coaxially sandwiched between a mold disk plate 1 and a work disk plate 2 whose disk surfaces face each other. The meandering continuous grooves 11 and 21 on the two disk plates 1 and 2 sandwich the rolling ball 9, and the ball holder 5 is locked by the rolling ball 9.

Next, the assembly of the mold disk plate 1, the ball holder 5 and the work disk plate 2 is placed in a metal case (not shown), and the mold disk plate 1, the work disk plate 2 and Is fixed so that the distance between them does not change, and the disk plate 2 to be processed and the ball holder 5 are rotatably held. As such a metal case, the cases 10 and 20 of the differential device shown in FIGS. 5 and 6 may be used, but the present invention is not particularly limited.

With the mold disk plate 1 fixed,
The ball holder 5 is rotated. As can be seen by paying attention to the pair of meandering continuous grooves 11 and 21 shown in FIG. 4, when the ball holder 5 rotates clockwise, the rolling ball 9 also moves clockwise. However, since the rolling ball 9 moves along the point A of the meandering continuous groove 11 of the fixed mold disc plate 1, the rolling ball 9 moves in the circumferential direction from the shape of the meandering continuous groove 11 at the point A. Try to move to On the other hand, in the meandering continuous groove 21 on the processed disk plate 2, when it is attempted to move in the circumferential direction from the point A, the processed disk plate 2 rotates clockwise. As described in the section of the related art, since the mold disk plate 1 is fixed, the rotation angle of the workpiece disk plate 2 is twice the rotation angle of the ball holder 5.

In the case where one rolling ball 9 is used, if the ball holder 5 makes at least one rotation, all the meandering continuous grooves 21 on the workpiece disk plate 2 pass through the rolling ball 9 and rolling is performed. . In this manner, the rolling ball 9 is forcibly moved along the meandering continuous groove 21 by the rotation of the ball holder 6, whereby the arc-shaped concave curved surface is rolled in the meandering continuous groove 21.

In the arcuate concave curved surface of the meandering continuous groove 21 obtained by rolling by the above method, the shape error is 100 μm or less, preferably 80 μm or less, and the surface roughness (Rz) is 10 μm or less, preferably 8 μm or less. It is. In this way, the concave wall surface of the meandering continuous groove for transmitting the force of the disk plate can be formed with few shape errors in only a few minutes. Further, the surface roughness of the finished surface is improved as compared with the cutting process.

Although the present invention has been described with reference to actual examples,
The present invention is not limited to these examples, and various modifications can be made without departing from the gist of the present invention. For example, the assembly shown in FIG. 1 can be put in a case, and a lubricant can be further added as needed.

[0048]

EXAMPLES Examples 1 and 2 The meandering continuous grooves of a disk plate for a differential gear were machined using the rolling device shown in FIG. The disk plate 1 is made of alloy tool steel (JIS) SKS3 (hardness HRC60)
It is. The rolling ball 9 is made of high carbon chromium bearing steel (JI
S) SUJ3 (hardness HRC62 or more), diameter 16.0
0 mm. The ball holder 5 has a diameter of 44 mm and a thickness of 5.
5 mm, made of chrome vanadium steel (JIS) SUP10 (hardness HRB400).

First, the disk 2 to be processed is cut, and the rolling allowance is about 0.1 mm (Example 1) and 0.2 m.
m (Example 2), a meandering continuous groove 21 having a U-shaped cross section was formed. In addition, the part which does not contribute to transmission of a force can also give relief. This primary processed disk plate 2 was assembled as shown in FIG. 1, assembled into a metal case, and set in a rolling device. In addition, 2
Each rolling ball 9 was used. Next, rolling was performed by rotating the ball holder 5 once with a torque wrench. Table 1 shows the rolling conditions.

The following items were measured for the processed disk plate 2, and the measurement results are shown in Table 1.

(1) Error in width of meandering continuous groove 21 The width (maximum part) of the meandering continuous groove is measured with a cylinder gauge,
The maximum error from the design value was determined.

(2) Three-dimensional position error of meandering continuous groove 21 The three-dimensional position of meandering continuous groove 21 was measured using a three-dimensional measuring device, and the maximum error from the design value was determined.

(3) Error in Section R of Meandering Continuous Groove 21 The radius R of the arc-shaped section of the meandering continuous groove 21 was measured using a three-dimensional measuring device, and an error range from the design value of 16.00 mm was obtained. .

(4) Surface Roughness (Rz) The surface roughness (Rz) of the concave wall surface transmitting the force of the meandering continuous groove 21
z) was measured using a roughness meter.

Table 1 Example 1 Example 2 Rolling allowance 0.1 0.2 (mm) Initial rolling initial torque 80 90 (kgm) First rolling torque 70 75 (kgm) Twice a day Rolling initial torque 65 70 (kgm) Torque during rolling twice 60 60 (kgm) Maximum error in width of meandering continuous groove 0.05 0.06 (mm) Positional error of meandering continuous groove 0.050 0.06 (mm) Cross-sectional R error of meandering continuous groove 0.02 0.03 (mm) Surface roughness (Rz) 57 (μm)

As shown in Table 1, Examples 1 and 2
The meandering continuous groove at the part transmitting the force of
mm and a rolled surface having a surface roughness (Rz) of 10 μm or less. By assembling this disk plate into a differential, torque can be transmitted stably.

Examples 3 and 4 Example 1 except that a rolling ball 9 of φ16.10 was used.
The disk plate 2 to be processed was processed in the same manner as described above. The force is transmitted to the processed disk plate 2 in the same manner as in the first embodiment. (1) The meandering continuous groove 21
(3) Error in the cross section R of the concave wall surface of the meandering continuous groove 21 and (4) Measurement of the surface roughness. Table 2 shows the results.

Table 2 Example 3 Example 4 Rolling allowance 0.1 0.2 (mm) Initial rolling initial torque 85 95 (kgm) First rolling torque 75 80 (kgm) Twice a day Rolling initial torque of 70 75 (kgm) Torque at twice rolling 65 70 (kgm) Maximum error of width of meandering continuous groove 0.04 0.05 (mm) Position error of meandering continuous groove 0.050 .05 (mm) Cross-sectional R error of meandering continuous groove 0.015 0.02 (mm) Surface roughness (Rz) 66 (μm)

As shown in Table 2, the meandering continuous groove of the portion transmitting the force in the third and fourth embodiments has a shape error of 100%.
This is a rolled surface having a surface roughness (Rz) of not more than 10 μm. By assembling this disk plate into a differential, torque can be transmitted stably.

[0060]

As described above, the differential device of the present invention has the following features.
Torque can be transmitted stably because the shape of the meandering continuous groove at the portion transmitting the force and the surface roughness are excellent. Also, this differential can be manufactured at low cost by rolling.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a part of an apparatus for manufacturing a differential device according to a preferred embodiment of the present invention.

FIGS. 2A and 2B are cross-sectional views showing meandering continuous grooves provided on a disk plate to be processed by primary processing, where FIG. 2A is a V-shaped cross section and FIG. 2B is a U-shaped cross section.

FIG. 3 is a sectional development view showing a meandering continuous groove provided on a disk plate to be processed by primary processing in a groove traveling direction;
(A) is a V-shaped recess, and (b) is a U-shaped recess.

FIG. 4 is a front view showing a state where a mold disk plate, a ball holder and a disk plate to be processed are combined.

FIG. 5 is a longitudinal sectional view showing a differential disclosed in Japanese Patent Application Laid-Open No. 8-170705.

FIG. 6 is an exploded sectional view of the differential shown in FIG. 5;

FIG. 7 is an exploded front view showing a pair of disk plates, a ball holder and balls in the differential shown in FIG. 5;

8 is a front view showing a state where one disk plate, a ball holder, and a ball of the differential device of FIG. 5 are combined.

FIG. 9 is a partially enlarged front view showing details of a meandering continuous groove of the disk plate of FIG. 8;

10 is a diagram in which one unit section of the meandering continuous groove of FIG. 9 is linearly developed.

FIG. 11 is a sectional view showing a sectional shape of a meandering continuous groove on a disk plate.

FIG. 12 is a schematic sectional view showing a special end mill for processing a meandering continuous groove provided on a disk plate.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Mold disk plate 11 ... Meandering continuous groove 12 ... Protrusion 2 ... Worked disk plate 21 ... Meandering continuous groove 3, 4 ... Disc Plates 31, 41 meandering continuous groove 31a first guide section 31b second guide section 31c third guide section 5, ball holder 51 guide hole 6 Balls 7, 8 Thrust washers 9 Rolling balls 10 Case 20 Case cover

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Yoshitaka Ito 2-1-2 Marunouchi, Chiyoda-ku, Tokyo F-term (reference) in Hitachi Metals Ball Tech Co., Ltd. 3J051 AA01 BA02 BB02 BD02 BE01 EC07 ED02 FA02

Claims (5)

[Claims] 1. An input-side rotating body that is rotated by a driving force from the outside, a pair of disk plates opposed to each other and arranged coaxially with the input-side rotating body, and arranged between opposing surfaces of the disk plates. A plurality of balls, and a holding body that holds each ball and rotates integrally with the input side rotating body, the holding body has a plurality of elongated holes extending in the radial direction of each disk plate, In a differential device in which each ball is movably accommodated in each elongated hole and a meandering continuous groove in which each ball is rotatably engaged is provided on an opposing surface of each disk plate, A differential device characterized in that a meandering continuous groove provided on a surface for transmitting force is assembled as a rolling surface having a shape error of 100 μm or less and a surface roughness (Rz) of 10 μm or less. 2. An input-side rotating body that is rotated by a driving force from the outside, a pair of disk plates opposed to each other and arranged coaxially with the input-side rotating body, and arranged between opposing surfaces of the disk plates. A plurality of balls, and a holding body that holds each ball and rotates integrally with the input side rotating body, the holding body has a plurality of elongated holes extending in the radial direction of each disk plate, The method of manufacturing a differential device, wherein each of the balls is movably accommodated in each of the long holes, and a meandering continuous groove in which each of the balls is rotatably engaged is provided on an opposing surface of each of the disk plates. A method for manufacturing a differential device, characterized in that a meandering continuous groove provided on the opposing surface of (1) is formed while moving while pressing a rolling ball. 3. The method of manufacturing a differential device according to claim 2, wherein the meandering continuous groove provided on the opposite surface of the disk plate is formed by: Plate and (2) rolling balls,
(3) a holding body for holding the rolling ball with a long hole extending in the radial direction; and (4) a die coaxially facing the disk plate to be processed and having a guide groove for the rolling ball. A disk plate for molding and (5) means for pressing the rolling ball against the disk plate to be processed are prepared, and one of the disk plate for molding and the disk plate to be processed is rotated to form a roll. A method for manufacturing a differential device. 4. The method for manufacturing a differential device according to claim 2, wherein the rolling allowance is 0.02 to 0.2 mm. 5. The method for manufacturing a differential device according to claim 2, wherein a radius of the rolling ball is +0.0 to 0.2 mm of a radius of a ball used for the differential device. A method for manufacturing a differential device.