JPH10113832A - Manufacture of dynamic pressure fluid beaking - Google Patents

Abstract

PROBLEM TO BE SOLVED: To very easily form dynamic pressure generating grooves and set the number of grooves and their inclination angle at will. SOLUTION: A spiral dynamic pressure generating groove 5 can be formed in the internal peripheral face of a bearing 4 by inserting a cutting tool 1 while rotating along the internal peripheral face of the bearing 4 by means of the groove forming edges 2 arranged in the external periphery of this cutting tool 1. In this constitution, the number and shape of dynamic pressure generating grooves 5 can be set at will by changing the rotation speed of the cutting tool 1 and the shape and number of the groove forming edges 2. It can be not the cutting tool but the bearing that is rotated.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a hydrodynamic bearing which rotatably supports a shaft of a spindle motor used as a disk drive source of a compact disk drive, a CD-ROM drive, or the like. More particularly, the present invention relates to a method for machining a dynamic pressure generating groove by a simple method.

[0002]

2. Description of the Related Art Conventionally, a shaft of a spindle motor used as a disk drive source of a compact disk drive or a CD-ROM drive has been rotatably supported by a bearing made of a metal body or a sintered body. In recent years, various types of so-called hydrodynamic bearings have been proposed in order to suppress shaft runout without providing a lateral pressure function. For example, Japanese Patent Application Laid-Open No. 47-36639 and Japanese Patent Application Laid-Open No. 3-107612 disclose various methods. Some have been disclosed.

[0003] In the production of ordinary sintered oil-impregnated bearings, the above-mentioned bearings are formed into a certain degree of bearing shape close to the shape of the final product at the time of pressure molding so that the shaft and the bearing make a band-like contact or a linear contact in the axial direction. Sinter the formed one,
After that, the sizing process is applied to press the belt-shaped or linear bearing inner wall surface formed in the axial direction to form a dense wall surface, and an oil film necessary for lubrication is formed between this wall surface and the shaft And fulfilled its function as a dynamic pressure bearing.

[0004]

However, in the above configuration, the molding die is preliminarily worked in accordance with the product shape so that a certain degree of bearing inner peripheral surface close to the final product shape is obtained at the time of molding. Since the shape is complicated, the processing is costly and time-consuming. In addition, in order to perform the sizing process, it is necessary to form a dynamic pressure generating groove in the axial direction, and such a dynamic pressure generating groove cannot form a uniform oil film on the outer peripheral surface of the shaft. Cannot be supported in good condition.

Therefore, the present invention solves the above-mentioned problems and makes it possible to extremely easily form the dynamic pressure generating grooves, and to arbitrarily set the number and the inclination angle of the dynamic pressure generating grooves. It is an object of the present invention to provide a method for manufacturing a hydrodynamic bearing that can be used.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a cutting tool is inserted while being rotated along the inner peripheral surface of the bearing, and the groove is provided on the outer peripheral surface of the cutting tool. A spiral dynamic pressure generation groove can be formed, and in this case, the dynamic pressure generation groove can be arbitrarily set by changing the rotation speed of the cutting tool, the shape and the number of the groove processing blades. Can be. In addition, a bearing may be rotated instead of a cutting tool.

[0007]

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a hydrodynamic bearing in which a shaft is rotatably supported and a dynamic pressure generating groove is formed on a sliding surface with the shaft. The dynamic pressure generating groove is formed by moving a cutting tool having a relative rotational relationship with a bearing in a shaft hole thereof.

A step of rotating either the cutting tool or the bearing in a predetermined direction to move it to a predetermined position in a shaft hole; and rotating the cutting tool or the bearing in a direction opposite to the direction to rotate an unprocessed portion in the shaft hole. It is effective to form a V-shaped dynamic pressure generating groove on the inner peripheral surface of the bearing by the step of moving the bearing. Further, the bearing is formed of a sintered oil-impregnated bearing, and a dynamic pressure generating groove is formed at both ends of the bearing by the cutting tool,
It is preferable to form an unprocessed portion in the center.

[0009]

FIG. 1 is an explanatory view showing a method of manufacturing a hydrodynamic bearing according to a first embodiment of the present invention.
FIG. 2 is a diagram showing the cutting tool in FIG. 1. In FIG. 1, reference numeral 1 denotes a cutting tool, and this cutting tool 1 has four grooves 2 at one end thereof. This grooving blade 2
Does not need to be four, and the number thereof can be set arbitrarily.

If the guide portion 3 is formed on the side where the groove 2 is formed as shown in FIG. 2, the positioning function can be achieved when the guide portion 3 is inserted into the shaft hole of the bearing 4. The groove processing blade 2 can be easily inserted into the shaft hole. Further, since the shape of the groove processing blade 2 can be easily changed as shown in FIGS. 3A to 3C, the shape of the dynamic pressure generating groove 5 can be changed to various shapes according to the groove processing blade 2. Can be set.

By using such a cutting tool 1, the bearing 4 is first fixed to a jig or the like, and the cutting tool 1 is inserted into the shaft hole while rotating. Then, a spiral dynamic pressure generating groove 5 is formed on the inner peripheral surface of the bearing 4 by the groove processing blade 2. Here, if the rotation speed of the cutting tool 1 is arbitrarily set, the inclination angle of the dynamic pressure generating groove 5 can be easily adjusted, and the dynamic force can be easily adjusted by changing the shape and number of the groove processing blades. The groove shape of the pressure generating groove or the interval thereof can be switched.

Also, the cutting tool 1 is kept in a fixed state,
There is no problem if the bearing 4 is rotated. Regarding the insertion of the cutting tool 1 and the bearing 4, even if the cutting tool 1 is reciprocated, the bearing 4 is reciprocated, or a combination thereof, there is no problem. Absent.

[0013]

Second Embodiment FIG. 4 is an explanatory view showing a method of manufacturing a hydrodynamic bearing according to a second embodiment of the present invention.
FIG. 3 is a view showing a working example of a dynamic pressure generating groove according to the present invention. First, in FIG. 4 (a), a dynamic pressure generating groove 5 is formed on the inner peripheral surface of the bearing 4 in the same manner as in the above-described embodiment, and when it is dug to a predetermined position, for example, the center of the bearing length. Then, as shown in FIG. 4B, the cutting tool 1 is rotated in a direction opposite to that of FIG.

Thus, the inner peripheral surface of the bearing 4 has V
It is possible to form the dynamic pressure generating groove 15 in the shape of a letter, and it is possible to form a uniform oil film on the outer peripheral surface of the shaft by holding oil more stably. Note that the shape of the dynamic pressure generating groove 15 and the like and whether to rotate the cutting tool 1 or the bearing 4 when forming the dynamic pressure generating groove can be implemented in the same manner as in the first embodiment. Needless to say.

According to such a method of manufacturing a hydrodynamic bearing, it is possible to provide hydrodynamic bearings having various shapes as shown in FIG. For example, FIG.
In (a), it goes without saying that the V-shaped dynamic pressure generating groove 15 can be formed as described in the above embodiment, and as shown in FIG. By inserting the cutting tool 1, it is also possible to form the dynamic pressure generating groove 25 while leaving the unprocessed portion of the dynamic pressure generating groove at the center in the length direction.

In this way, as shown in FIG. 3C, even when the bearing 4 has a step in its shaft hole, the dynamic pressure generating groove 35 is formed in the same manner as in FIG. Can be formed, for example, if the bearing is a sintered oil-impregnated bearing,
At low speeds, it acts as a normal oil-impregnated sintered bearing. At high speeds, it acts as a hydrodynamic bearing by means of hydrodynamic grooves formed at both ends.

The present invention is not limited to the above embodiments, but can be implemented with various modifications without departing from the scope of the invention. For example, in FIG. 4, the bearing is fixed, and the cutting tool moves while rotating in the shaft hole, and reversely rotates at a predetermined position to form a V-shaped dynamic pressure generating groove. Separately, when the cutting tool is moved to a predetermined position in the shaft hole by rotating in a predetermined direction, the cutting tool is once pulled out, the bearing is inverted, and then the cutting tool is rotated in the reverse direction to form a V-shape. Even if the dynamic pressure generating groove is formed, there is no problem at all.

[0018]

As described above, according to the present invention, the dynamic pressure can be increased by moving the cutting tool having the groove machining blade on the outer periphery in the shaft hole with the relative rotational relationship with the bearing. Since the configuration is such that the generation grooves are formed, various dynamic pressure generation grooves can be formed by a simple method by changing the rotational speed of the cutting member, the shape and number of the groove processing blades.

Further, after rotating either the cutting tool or the hydrodynamic bearing in a predetermined direction, by rotating the cutting tool or the hydrodynamic bearing in the opposite direction, the V-shape is formed on the inner peripheral surface of the hydrodynamic bearing in a simple manner. A dynamic oil pressure generating groove can be formed, and a uniform oil film can be formed on the outer peripheral surface of the shaft by more stable oil holding.

Also, if a cutting member is inserted from both ends of a hydrodynamic bearing composed of a sintered oil-impregnated bearing and is formed so as to have an unprocessed portion at the center, stable shaft holding from high speed to low speed can be realized. it can.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing a method for manufacturing a hydrodynamic bearing according to a first embodiment of the present invention.

FIG. 2 is a view showing the cutting tool in FIG. 1;

FIG. 3 is a view showing a shape of a groove machining blade of the cutting tool in FIG. 1 or FIG. 2;

FIG. 4 is an explanatory view showing a method of manufacturing a hydrodynamic bearing according to a second embodiment of the present invention.

FIG. 5 is a diagram showing a working example of a dynamic pressure generating groove according to the present invention.

[Explanation of symbols]

 1) Cutting tool 2) Groove cutting blade 4) Bearing 5) Dynamic pressure generating groove

Claims (3)

[Claims] 1. A method of manufacturing a hydrodynamic bearing in which a shaft is rotatably supported and a dynamic pressure generating groove is formed on a sliding surface with the shaft, wherein a cutting tool having a groove processing blade is provided with a bearing. Wherein the dynamic pressure generating groove is formed by moving in the shaft hole with the relative rotational relationship of (1). 2. A step of rotating either the cutting tool or the bearing in a predetermined direction to move it to a predetermined position in a shaft hole, and rotating the cutting tool or the bearing in a direction opposite to the direction to rotate the unprocessed portion in the shaft hole. 2. The method of manufacturing a hydrodynamic bearing according to claim 1, wherein the step of moving the groove forms a V-shaped dynamic pressure generating groove on the inner peripheral surface of the bearing. 3. The bearing comprises a sintered oil-impregnated bearing, wherein a dynamic pressure generating groove is formed at both ends of the bearing by the cutting tool, and a central portion has an unprocessed portion.
A manufacturing method of the hydrodynamic bearing according to the above.