JP2002323043A - Linear motion bearing mechanism and manufacturing method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a linear motion bearing mechanism and a manufacturing method therefor that enables a mass production by plastic forming mainly. SOLUTION: The mechanism has a shaft 11, an outer cylinder 12, a number of steel balls 13 that exist between the shaft 11 and the outer cylinder 12 and a retainer 14 holding these steel balls 13. In the shaft 11, straight grooves 19 are formed at every regular angle (90 degrees) in the axial direction on the circumference surface of a groove formation part 11a. The depth d of the straight grooves is to be 6 to 14% of the diameter D of the steel ball 13. On the other hand, a recessed part 21 is formed of straight parallel ribs 20, 20 as a rolling groove for the steel balls 13 in the retainer 14, and the retainer 14 is fitted and held to a regular position, in the through-hole 15 of the outer cylinder 12. This depth d is to be 6 to 14% of the diameter D of the steel ball 13.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a linear motion bearing mechanism which can be manufactured mainly by plastic working and can be mass-produced, and a method of manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, a linear motion bearing mechanism 1 in which a large number of rolling elements (steel balls) are rotatably held by a retainer (retainer) so as to move linearly along an axis. Has been The linear motion bearing mechanism 1 includes a shaft 3 having a rolling groove 2, an outer cylinder 6 provided with a retainer 5 holding a steel ball 4, and a rolling groove 2 formed on the inner diameter side of the outer cylinder 6. (See FIG. 6). An endless track groove (not shown) is formed in the retainer 5 for holding and running a large number of steel balls 4, and one straight portion of the endless track groove is exposed in a slit shape to form a shaft. Rolling groove 2 formed in 3
The steel ball 4 is contacted and rolled so that the outer cylinder 6 and the shaft 3 do not rotate in the circumferential direction, and can be relatively moved in the axial direction.

[0003]

In this case, the steel ball 4 and the rolling groove 2 of the shaft 3 and the rolling groove 2 'of the outer cylinder 6 have a depth of, for example, about 35 to 40% of the rolling element diameter. , The steel ball 4 and approximately 9
Since the groove width is provided so as to make contact within a range of 0 degrees, forming the two rolling grooves 2 and 2 'for this requires grinding and is troublesome, so mass production is difficult. However, an increase in manufacturing costs was inevitable. The outer cylinder 6 is attached to the shaft 3.
At the time of mounting, when the rolling groove 2 of the shaft 3 is matched with the endless track groove of the retainer 5, the steel ball 4 may fall off from the retainer 5. SUMMARY OF THE INVENTION The present invention has been proposed to overcome the above problems, and has as its object to provide a linear motion bearing mechanism and a method of manufacturing the linear motion bearing mechanism, which can be manufactured mainly by plastic working and can be easily mass-produced. And

[0004]

In order to solve the above-mentioned problems, according to the present invention, in claim 1, a shaft, an outer cylinder, a plurality of rolling elements interposed between the shaft and the outer cylinder, and the rolling elements A linear motion bearing mechanism comprising a retainer for holding the retainer at a fixed position on an inner wall surface of an insertion hole through which the shaft is inserted via the retainer, and a rolling element for rolling. A linear motion bearing mechanism is disclosed in which a linear parallel rib as a groove is formed, and a linear groove is formed on the shaft side so as to face the linear parallel rib. Also, in the present invention, a linear motion bearing mechanism is disclosed in claim 2, wherein the depth of the linear parallel rib as a rolling groove is 6 to 14% of the diameter of the rolling element. According to the present invention, a linear motion bearing mechanism is disclosed in claim 3 in which the depth of the linear groove on the shaft side is 6 to 14% of the diameter of the rolling element. According to the present invention, in claim 4, the rolling groove of the outer cylinder is formed by grinding the inner and outer surfaces from a material.
A method for manufacturing a linear motion bearing mechanism formed by performing plastic working and heat treatment is disclosed. Further, in the present invention, in claim 5, the straight groove of the shaft is formed by external grinding, plastic working,
A method of manufacturing a linear motion bearing mechanism formed through heat treatment is disclosed.

According to the first aspect of the invention, when the retainer holding the rolling element is mounted on the outer cylinder, the linear parallel rib is fitted with the raceway groove of the retainer, and the stopper is pressed into both ends of the retainer. In this case, the retainer can be assembled to the outer cylinder without rattling.

According to the second aspect of the present invention, the outer diameter grinding step is performed as a pre-process of the plastic working, whereby the dimensions and the shape are made uniform. Since it is 6 to 14%, the dimensional accuracy after plastic working can be kept high, and the deformation after heat treatment is small, so that the process can be simplified.

According to the third aspect of the present invention, the outer diameter grinding step is carried out as a pre-process of the plastic working, whereby the dimensions and shapes are made uniform, and the depth of the linear groove on the shaft side is adjusted to 6 to 14 times the diameter of the rolling element.
%, The dimensional accuracy after plastic working can be kept high, and the deformation after heat treatment is small, so that the process can be simplified.

According to the fourth aspect, the outer cylinder can be formed by subjecting the inner and outer surfaces to dimensional processing and plastic processing, and formed by heat treatment, so that the manufacturing process can be simplified and mass production is possible.

According to the fifth aspect, the shaft can be formed by dimensional processing of the shaft end portion, then, after the outer surface grinding of the groove forming portion, plastic forming and heat treatment, and mass production is possible. It is.

[0010]

Next, one embodiment of a linear motion bearing mechanism and a method of manufacturing the same according to the present invention will be described with reference to the accompanying drawings. FIG. 1 shows a direct-acting bearing mechanism 10. The direct-acting bearing mechanism 10 includes a shaft 11, an outer cylinder 12, a number of rolling elements interposed between the shaft 11 and the outer cylinder 12, that is, steel balls 13, It is substantially constituted by a retainer 14 for holding the ball 13. The shaft 11 has, at both ends, a support portion 11b having a smaller diameter than the groove forming portion 11a in which the outer cylinder 12 is mounted, and a component mounting portion 11c for attaching another mechanical component to the tip of one of the support portions 11b. Has been processed. The outer cylinder 12 is connected to a shaft 11 via a retainer 14.
Has a through hole 15 through which a flange 16
Are provided integrally. Also, on both ends of the outer cylinder 12,
A retaining ring 17 is fixed so that the retainer 14 does not come off from the inside of the outer cylinder 12. The retainer 14 is a cylindrical member. The inner diameter is larger than the outer diameter of the shaft 11, and the outer diameter is smaller than the inner diameter of the outer cylinder 12. The retainer 14 has four endless track grooves 18 on its outer periphery for holding a large number of steel balls 13 in a freely rolling manner, and is equiangular (90 in circumferential direction).
°) (see FIG. 2). The endless track groove 18 includes a pair of straight portions 18a and a turning portion 18b. One of the straight portions 18a is a retainer 1
4 is a steel ball that penetrates through the cylindrical wall surface and that runs while rolling.
However, the load region L contacts the shaft member to be supported.

Next, in the shaft 11, a groove forming portion 11a
The straight groove 19 is formed at an equal angle (90
Each degree is formed (see FIG. 1). Such a straight groove 1
The depth d of 9 is 6 to 14% of the diameter D of the steel ball 13. On the other hand, the retainer 14 is fitted and held in a fixed position in the insertion hole 15 of the outer cylinder 12, and the linear parallel ribs 20, 20 as rolling grooves of the steel balls 13 in the retainer 14 are provided.
(See FIG. 3).

In the insertion hole 15 of the outer cylinder 12, as shown in FIG. 4, the linear parallel ribs 20, 20 have a concave portion 21 having an appropriate depth between the ribs 20, 20 and a steel ball 13.
It is machined as a rolling groove. Such ribs 20, 20
The depth d of the concave portion 21 is 6 to 14 of the diameter D of the steel ball 13.
%. In addition, the outer cylinder 12 has the flange portion 16 formed integrally, but of course, the outer cylinder 12 having no flange portion is also possible.

Next, the manufacturing process of the shaft 11 and the outer cylinder 12 in the linear motion bearing mechanism 10 as described above will be schematically described. The shaft 11 is made of 1. Groove forming portion 11a, support portion 1
1b, processing of the component mounting portion 11c; 2. outer surface grinding of the groove forming portion 11a; 3. Pull out. It is formed through heat treatment (carburizing quenching or induction quenching, tempering).

On the other hand, the outer cylinder 12 is made of 1.. 1. Internal and external grinding 2. cold forging; The heat treatment (carburizing quenching, tempering) is performed to form.

In the linear motion bearing mechanism 10 as described above,
First, when loading the retainer 14 into the outer cylinder 12, the outer cylinder 1
The load region L of the linear portion 18a of the endless track groove 18 in the retainer 14 is matched with the two parallel ribs 20 on the two sides. Then, the retainer 14 is inserted until the turning portion 18b of the endless track groove 18 is left, and the steel ball 13 is put into the endless track groove 18 via the turning portion 18b. If the retainer 14 is mounted in this manner and the retaining rings 17 are pressed into both ends of the retainer 14, the retainer 14 can be assembled to the outer cylinder 12 without rattling.

The straight groove 19 in the groove forming portion 11a on the shaft 11 side and the concave portion 21 having a depth d of the straight parallel ribs 20 and 20 in the insertion hole 15 of the outer cylinder 12 are formed with a diameter D of the steel ball 13.
Therefore, a smooth movement with less running resistance can be obtained.

The depth d of the linear groove 19 in the groove forming portion 11a on the shaft 11 side is a fine groove of 6 to 14% of the diameter D of the steel ball 13, and the outer diameter is reduced by the grinding in the previous step. Since the dimensions are set to be constant, the amount of processing by plastic working is small, and therefore, the deformation by subsequent heat treatment is also small.

On the other hand, in the outer cylinder 12 as well, the depth of the straight parallel ribs 20, 20 in the insertion hole 15 is only 6 to 14% of the diameter D of the steel ball 13, and the grinding process in the previous step Since the dimensions of the inner and outer diameters are made uniform, the amount of processing by plastic working is small, and therefore, the deformation by subsequent heat treatment is also small. Since the steps can be simplified in this way, mass production is easy, and therefore, production costs can be suppressed. The straight groove 1 of the shaft 11
9. The processing of the concave surface portion 21 which is a rolling groove in the linear parallel ribs 20 and 20 of the outer cylinder 12 may finally add a lapping process, if necessary, for the purpose of ensuring accuracy.

[0019]

According to the present invention, a smoother movement can be obtained while suppressing running resistance. In addition, the formation depth of the straight groove on the shaft side and the straight parallel rib in the insertion hole of the outer cylinder is
It is only 6-14% of the diameter of the rolling element.
Elaborate processing such as a groove having a large contact angle with the rolling element (a groove having a depth of 35 to 40% of the diameter of the rolling element by grinding) is unnecessary, and can be manufactured by plastic processing. Suitable for mass production. Therefore, the production cost can be reduced.

[0020]

[Brief description of the drawings]

FIG. 1 is a side view, partially broken away, showing one embodiment of a linear motion bearing mechanism according to the present invention.

FIG. 2 is a configuration diagram of an assembly of an outer cylinder and a retainer in the linear motion bearing mechanism shown in FIG. 1;

FIG. 3 is a front view of the outer cylinder shown in FIG. 2;

FIG. 4 is an enlarged view of an insertion hole in the outer cylinder shown in FIG.

FIG. 5 is an explanatory sectional view of a main part showing a contact state between a steel ball, an outer cylinder and a shaft in a retainer.

FIG. 6 is an explanatory diagram for explaining a contact relationship between a rolling element and a rolling groove in a conventional linear motion bearing mechanism.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 linear bearing mechanism 2, 2 ′ rolling groove 3 shaft 4 steel ball 5 retainer 6 outer cylinder 10 linear bearing mechanism 11 shaft 11 a groove forming portion 11 b support portion 11 c component mounting portion 12 outer cylinder 13 steel ball 14 retainer 15 insertion Hole 16 Flange part 17 Retaining ring 19 Straight groove 18 Endless track groove 18a Straight part 18b Revolving part 20 Straight parallel rib 21 Concave part

Claims (5)

[Claims] 1. A linear motion bearing mechanism comprising a shaft, an outer cylinder, a number of rolling elements interposed between the shaft and the outer cylinder, and a retainer holding the rolling elements, wherein the outer cylinder is a retainer. On the inner wall surface of the insertion hole through which the shaft is inserted, a retainer is fitted and held at a fixed position, and a linear parallel rib as a rolling groove of a rolling element is formed. A linear motion bearing mechanism characterized in that a straight groove is formed. 2. The linear motion bearing mechanism according to claim 1, wherein a depth of the linear parallel rib as a rolling groove is 6 to 14% of a diameter of the rolling element. 3. The linear motion bearing mechanism according to claim 1, wherein the depth of the linear groove on the shaft side is 6 to 14% of the diameter of the rolling element. 4. The method according to claim 1, wherein the rolling grooves of the outer cylinder are formed by performing inner and outer surface grinding, plastic working, and heat treatment from a material. . 5. The method according to claim 1, wherein the linear groove of the shaft is formed from a material through external grinding, plastic working, and heat treatment.