JPH0459107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming minute recesses in the inner diameter surface of a cylindrical article.

B. Prior Art The inner diameter surface b of a cylindrical article a shown in FIG. 1, which is generally used as a dynamic pressure bearing used at high speeds, has minute recesses c that become pressure reservoirs as shown in FIGS. 2 A to C. is formed over the entire length of the inner diameter surface b. The depth of the micro-concavity c is usually 3/1000.
mm, the processing area is 1/ of the circumference of the inner diameter surface of cylindrical article a
It is set to about 2 to 1/3.

By the way, processing of the above-mentioned minute recesses c on the inner diameter surface b of the cylindrical article a has conventionally been carried out as follows. That is, as shown in FIGS. 3 and 4, the outer diameter surface of a cylindrical article a is held between chucks 1,
After fixing the cylindrical article a so as not to rotate, the grindstone 3 supported cantilevered by the spindle 2 is rotated and inserted into the inner diameter surface of the cylindrical article a with a small machining allowance, and the grindstone 3 is turned into a cylindrical shape. By sliding the article a in the axial direction and grinding it, a minute recess c is formed in the inner diameter surface b of the cylindrical article a.

However, when the minute recesses c were formed in the inner diameter surface b of the cylindrical article a by the above method, the following drawbacks occurred. That is, since a large moment load is applied to the spindle 2 supporting the grinding wheel 3 in a cantilevered manner during grinding, rigidity is required. Therefore, spindle 2
It was not possible to make the overall length of the machine very long. Therefore, if the cylindrical article a is long, simply inserting the grindstone 3 into the cylindrical article a from one open end will not form the minute recess c over the entire length of the inner diameter surface b of the cylindrical article. This resulted in the necessity of inserting the grindstone 3 into the inner diameter surface of the cylindrical article a from both open ends, which resulted in the disadvantage that the cylindricity of the minute recesses c was destroyed. Also, on the inner diameter surface b of the cylindrical article a, 1/2 to 1/2 of the circumference of the inner diameter surface
In order to grind a micro-concavity c of about 1/3, a grindstone 3 whose diameter is slightly smaller than the inner diameter of the cylindrical article a is used. When the grindstone 3 is inserted into the cylindrical article a, the grindstone 3 may come into contact with the end surface of the cylindrical article a, and the grindstone 3 may be damaged.

(b) Purpose of the invention When forming a minute recess over the entire length of the inner diameter surface of a cylindrical article, accurate processing can be performed without destroying the cylindricity even if the cylindrical article is long. be.

C. Structure of the invention The diameter is slightly smaller than the inner diameter dimension of the cylindrical workpiece, the total length is approximately twice or more the length of the workpiece, and the outer peripheral surface is coated with fine abrasive grains. After placing a workpiece supported by a fixing jig that prevents rotation of the workpiece on the outer periphery of the processing shaft formed with a film, both ends of the processing shaft are rotatably supported by the center, By rotating the machining shaft with the outer peripheral surface of the machining shaft in line contact with the inner diameter surface of the workpiece, a minute recess is machined on the inner diameter surface of the workpiece.

D. Example FIGS. 5 and 6 are drawings showing a specific example of machining a minute recess c in the inner diameter surface b of a cylindrical article a using a cylindrical grinder according to the machining method according to the present invention. be. In the figure, 10 is a processing shaft for processing the inner diameter surface b of the cylindrical article a, and the processing shaft 10 is hardened and has a coating layer of fine abrasive grains formed on its surface by plating. An electroplated grindstone is used. In addition, the total length of the processing shaft 10 is set to be approximately twice the total length of the cylindrical article a, and its diameter is calculated based on what percentage of the inner diameter surface b of the cylindrical article is to be machined. . 11, 11 is a center of the cylindrical grinder for supporting the processing shaft 10 from both ends; 12 is a rotation device of the cylindrical grinder for rotating the processing shaft 10 supported by the centers 11; 11 is a rotation device; This is a celery for connecting the device 12 and the processing shaft 10. 14 is the processing axis 10
15 is an arm extending outward from the outer periphery of the fixing jig 14, and 16 is a slide rod arranged parallel to the processing axis 10. , the arm 15
comes into contact with the slide rod 16, so that the fixing jig 14 supporting the cylindrical article a is moved to the processing shaft 10.
This prevents it from rotating. As a means for preventing rotation of the fixing jig 14, instead of providing the arm 15 on the outer periphery of the fixing jig 14, a weight may be suspended below the fixing jig 14.

In the above configuration, in order to form a minute recess c in the inner diameter surface b of the cylindrical article a by the processing method according to the present invention, first the keret 13 is attached to one end of the processing shaft 10, and then the fixing jig 14 is attached to the outer periphery. The processing shaft 10 is inserted through the inner diameter surface of the cylindrical article a equipped with the cylindrical article a.
Next, connect both ends of this processing shaft 10 to centers 11, 11.
The arm 15 protruding from the fixture 14 is supported rotatably by the slide rod 1, and the machining shaft 10 is brought into contact with the rotating device 12 via the support 13.
6 to prevent the cylindrical article a from rotating, and at the same time bring the inner diameter surface b of the cylindrical component a into line contact with the outer circumferential surface of the processing shaft 10. In this state, the processing shaft 10 is rotated, and at the same time, the fixing jig 14 is slid in the axial direction of the processing shaft 10 by any means, and the cylindrical article a is slid in the axial direction on the processing shaft 10. Then, since the inner diameter surface b of the cylindrical article a and the outer circumferential surface of the processing shaft 10 are in line contact, a minute recess c is formed in the inner diameter surface b of the cylindrical article a.
Note that the reason why the cylindrical article a is slid in the axial direction is to facilitate processing of the inner diameter surface b of the cylindrical article.

E. Effects of the Invention As described above, if the processing shaft for processing the inner diameter surface of a cylindrical article is rotated with its both ends supported, a long processing shaft can be used. Therefore, even if the cylindrical article to be processed is long, minute recesses can be formed in the inner diameter surface in a single process, so that the cylindricity of the processed part will not deteriorate. Furthermore, since the processing shaft is rotated after being inserted into the inner diameter surface of the cylindrical article, the processing shaft will not come into contact with the end surface of the cylindrical article and be damaged when the processing shaft is inserted into the inner diameter surface of the cylindrical article.

[Brief explanation of drawings]

Fig. 1 is a sectional view showing an example of a cylindrical article;
Figures A to C are drawings showing various shapes of minute recesses, Figures 3 and 4 are schematic diagrams for explaining the conventional inner diameter surface machining method, and Figures 5 and 6 are inner diameter surfaces according to the present invention. It is a schematic diagram for explaining a processing method. a... Cylindrical article, b... Inner diameter surface, c... Minute recess, 10... Machining axis, 11... Center, 12
...Rotating device, 14...Fixing jig.

Claims (1)

[Claims] 1 The diameter is slightly smaller than the inner diameter of the cylindrical workpiece, the total length is approximately twice or more than the length of the workpiece, and a film of fine abrasive grains is formed on the outer peripheral surface. After placing the workpiece supported by a fixing jig that prevents rotation of the workpiece around the outer circumference of the processing shaft, both ends of the processing shaft are rotatably supported by the center. The inner diameter of a cylindrical article, characterized in that a minute recess is machined on the inner diameter surface of the workpiece by rotating a processing shaft while the outer peripheral surface and the inner diameter surface of the workpiece are in line contact. Surface processing method.