JPH08232958A - Manufacturing method of sleeve for fluid bearing - Google Patents

Abstract

PURPOSE: To provide a manufacturing method of a sleeve for a fluid bearing capable of removing a raised part of an inside diametrical surface without requiring a chuck. CONSTITUTION: A process to machine a groove 2 for dynamic pressure generation on an inside diametrical surface 1A of a sleeve 1 and a reamer machining process to remove a raised part adjacent to the groove 2 for dynamic pressure generation made due to machining by cutting it by a reamer 12 are included. In reaming, as the sleeve 1 of a reamed article is elastically supported by an elastic member 11 in the radial direction and the raised part is cut and machined under an inside diametrical surface standard without chucking, the inside diametrical surface of the sleeve is neither deformed nor concentricity with an outside diametrical surface is deteriorated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a hydrodynamic bearing sleeve having a groove for generating a dynamic pressure on its inner diameter surface, and more particularly to a method for manufacturing a hydrodynamic bearing sleeve having good dimensional accuracy.

[0002]

2. Description of the Related Art A sleeve for a hydrodynamic bearing of this type is made of a soft metal such as brass or aluminum alloy. The dynamic pressure generating groove is
Rolled by a method in which a jig in which a plurality of hard balls are arranged radially at the tip of the shaft so as to project slightly from the sleeve inner diameter surface is pushed axially while turning to the sleeve inner diameter surface left or right. It

The raised portion adjacent to the dynamic pressure generating groove formed by the plastic working by ball rolling is, for example, Japanese Patent Publication No. 3-31.
As shown in No. 929, it is removed by cutting with a lathe. 2 to 4 show a procedure for manufacturing a conventional sleeve for a hydrodynamic bearing. FIG. 2 shows a pre-processing step in which an inner diameter surface 1A of the sleeve 1 is cut by a lathe. FIG. 3 is a rolling process of the dynamic pressure generating groove 2 on the inner diameter surface 1A of the sleeve by the rolling device, in which the raised portion 3 is formed adjacent to the dynamic pressure generating groove 2. FIG. 4 is a step of removing the raised portion 3 formed on the inner diameter surface 1A of the sleeve, which is cut and removed by a lathe.

[0004]

However, in the conventional method for manufacturing a sleeve for a hydrodynamic bearing described above, the outer diameter surface 1B of the sleeve 1 is chucked to a lathe (not shown) in the step of removing the raised portion shown in FIG. Since the inner diameter surface 1A is cut according to the so-called sleeve outer diameter surface reference, the sleeve inner diameter surface 1A is deformed by a chucking force, or the coaxiality of the inner diameter surface 1A with respect to the outer diameter surface 1B is slightly shifted due to a chuck error. In addition to the problems, it is difficult to reduce variations in inner diameter.

More specifically, if the ridge 3 is cut and removed while the inner diameter surface 1A is slightly deformed by the chuck pressure, the inner diameter surface 1 is released by releasing the chuck.
Since A is restored to its original shape, the axial shape of the sleeve inner diameter surface 1A is deteriorated, resulting in deterioration of bearing performance. Further, when the coaxiality becomes poor, when the sleeve 1 is used in the so-called sleeve rotation in which the sleeve 1 is rotated with respect to the fixed shaft, the sleeve 1
There is a performance problem that the specimen fitted to the outer diameter surface 1B vibrates in the radial direction.

Further, since the inner diameter surface 1A is cut by a lathe, its size is determined by the feed of the cutting tool. However, since the feed of the cutting tool is affected by the precision of the feed table and the change of the ambient temperature, it is difficult to suppress the variation in the inner diameter within 2 μm which is required for the fluid bearing as a practical problem. Therefore, the present invention has been made by paying attention to the problem in processing such a conventional fluid bearing sleeve, and manufacture of a fluid bearing sleeve capable of removing the raised portion of the inner diameter surface without the need for a chuck. The purpose is to provide a method.

[0007]

SUMMARY OF THE INVENTION The present invention relates to a method of manufacturing a fluid bearing sleeve having a groove for dynamic pressure generation on the inner diameter surface, and a step of processing a groove for dynamic pressure generation on the inner diameter surface of the sleeve, And a reamer processing step of removing a raised portion adjacent to the dynamic pressure generating groove caused by the processing.

[0008]

The dynamic pressure generating groove is formed on the inner diameter surface of the sleeve, and the raised portion formed adjacent to the dynamic pressure generating groove is removed by reaming. In the reaming process, at least one of the sleeve that is the workpiece and the reamer that is the processing tool is elastically supported in the radial direction, and the raised portion is cut based on the inner diameter surface reference without chucking. Will not be deformed or the coaxiality with the outer diameter surface will not deteriorate.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, in which a cylindrical sleeve 1 as a workpiece is already processed into a pre-processing step for the sleeve 1 by a lathe similar to the conventional one and a sleeve inner diameter surface 1A by a rolling device. The rolling processing of the dynamic pressure generating groove 2 has been completed, and a ridge portion (not shown) is formed adjacent to the dynamic pressure generating groove 2 on the inner diameter surface 1A.

The following steps are reamer processing steps for removing the raised portions. The sleeve 1 is supported by the base 10. The pedestal 10 is provided with a cylindrical sleeve support base portion 10A having an inner diameter larger than the outer diameter of the sleeve 1, and the sleeve 1 is mounted on the inner diameter surface of the sleeve support base portion 10A in an axially spaced manner. It is elastically supported in the radial direction via two O-rings (elastic members) 11. Therefore, the inner diameter surface 1A of the sleeve is never deformed by the chucking force.

The reamer 12 is attached to the sleeve 1 thus supported.
Is inserted while rotating, and the protruding portion of the inner diameter surface 1A is removed by cutting while pushing the introduction portion 12A and the outer surface 12B in the axial direction. In this raised portion cutting process, it is not necessary to particularly limit the rotation direction of the reamer 12. When the sleeve 1 is elastically supported in the radial direction via the O-ring in this way, the sleeve 1 does not easily rotate in the rotational direction regardless of the rotational direction of the reamer 12, so that the raised portion of the inner diameter surface 1A of the sleeve is rotated. The outer surface 12B of the reamer 12 can be cut and removed by a so-called inner diameter surface standard. Therefore, the coaxiality between the outer diameter surface 1B and the inner diameter surface 1A of the sleeve 12 is extremely good.

Moreover, since the inner diameter of the sleeve 1 is determined by the outer surface 12B of the reamer 12, even if there is some variation in the inner diameter in the pre-processing step and the rolling step, it is within 2 μm necessary for the fluid bearing in the reamer processing. It is easy to suppress the variation. As described above, according to this embodiment, in removing the raised portion of the inner diameter surface 1A of the sleeve 1, the sleeve inner diameter surface 1A is not deformed by the chucking force, and the sleeve inner diameter surface 1A and the outer diameter surface 1B are removed. Since the coaxiality with and is extremely good, and the variation of the inner diameter can be suppressed within 2 μm, it is highly dimensional accuracy, and there is no risk of vibration during use. The effect is that the sleeve can be manufactured.

Further, according to this embodiment, since the O-ring 11 is used to support the sleeve 1 of the work piece on the pedestal 10, the elastic support can be performed easily, inexpensively and surely. The effect is obtained. Further, since the variation of the inner diameter of the sleeve 1 can be easily made within 2 μm by the reaming, the allowable inner diameter in the pre-processing step by the lathe can be made larger than the conventional one, and the lathe machining time can be greatly shortened. Is obtained.

In this embodiment, the O-ring is used to elastically support the sleeve 1, but the present invention is not limited to this, and other elastic members such as a D ring, an X ring and a U ring are used. Good. Further, a plurality of coil springs may be radially arranged and elastically supported in the radial direction. Also,
In the embodiment, the method of reaming by elastically supporting the sleeve has been described, but on the contrary, the sleeve is fixed,
The reamer may be processed by floatingly supporting it through an elastic member. Alternatively, both the sleeve and the reamer may be elastically supported for processing.

Further, as shown in FIG. 1, the reamer 12 has an introduction portion 12 having a diameter slightly smaller than the outer surface 12B having a predetermined outer diameter.
It is preferable to provide A because it is possible to prevent the reamer from sticking to the sleeve inner diameter surface 1A during processing. However, the introduction part 12A does not necessarily have to be provided. Further, the shape of the blade of the reamer introduction portion 12A and the outer surface 12B may be a straight shape that is straight in the axial direction or a spiral shape having a twist.

In this embodiment, the case where the dynamic pressure generating groove is rolled by plastic working with balls has been described.
In addition, in the case of a processing method in which a groove for dynamic pressure generation is formed on the inner diameter surface of the sleeve by cutting using a jig having a plurality of cutting blades on the outer diameter surface of the shaft, Since adjacent ridges are formed, the manufacturing method of the present invention can be preferably applied.

[0017]

As described above, according to the present invention, the raised portion generated by the rolling process of the groove for generating the dynamic pressure on the inner diameter surface of the sleeve is removed by the reaming process. Since at least one of the sleeve and the reamer of the processing tool is elastically supported in the radial direction and the raised portion is cut based on the inner diameter surface reference, the inner diameter surface of the sleeve is deformed like the chuck support and the outer diameter surface Since the coaxiality does not deteriorate, vibration of the sample is prevented even when used with sleeve rotation, and since the raised part is not cut with a cutting tool, it can be processed within the specified dimensional accuracy. As a result, there is an effect that it is possible to process a fluid bearing sleeve having extremely good performance.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a reamer processing step according to an embodiment of the present invention.

2A and 2B are views illustrating a pre-processing step in a conventional method for manufacturing a fluid bearing sleeve, in which FIG. 2A is a sectional view of the front surface of the sleeve and FIG.

3A and 3B are diagrams illustrating a rolling process of a groove for generating a dynamic pressure in a conventional method for manufacturing a sleeve for a hydrodynamic bearing, FIG. 3A is a sectional view of the front surface of the sleeve, and FIG. 3B is a sectional view taken along line BB thereof. It is a figure.

4A and 4B are diagrams illustrating a step of removing a raised portion in a conventional method for manufacturing a sleeve for a hydrodynamic bearing, in which FIG. 4A is a sectional view of the front surface of the sleeve, and FIG. 4B is a sectional view taken along line BB thereof.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sleeve 2 Dynamic pressure generating groove 3 Raised part 11 Elastic member (O-ring) 12 Reamer

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomita Suzuki, 1-5-50, Kuminuma Shinmei, Fujisawa-shi, Kanagawa NSK Ltd. (72) Inventor, Koichi Kawakami 1-5-50, Kuminuma, Kinsawa, Kanagawa Prefecture No. within NSK Ltd.

Claims (1)

[Claims] 1. A method of manufacturing a hydrodynamic bearing sleeve having a dynamic pressure generating groove on its inner diameter surface, the method comprising the steps of processing a dynamic pressure generating groove on the inner diameter surface of the sleeve, and the motion generated by the processing. And a reamer processing step of removing a raised portion adjacent to the pressure generating groove.