JPS63242422A - Manufacture of fluid bearing - Google Patents

Abstract

PURPOSE:To improve the quality of a fluid bearing and to effect the mass production by providing a projecting bar for grooving on the outer diameter face of a punch, inserting it onto the same axis with a sleeve as well and then passing the sleeve by pushing it into a die hole with a punch. CONSTITUTION:Plural projection bars 13 corresponding to the groove shape of a fluid bearing are formed on the outer diameter face 12 at the small diameter part of one end of a bar-like punch 11. The comparatively soft sleeve 15 made of brass alloy is then prepared to form the inner diameter larger by adequate amt. then the outer diameter D1 of the grooving part 14 of the punch 11. The grooving part 14 is inserted onto the same axis of the sleeve 15, which is passed into a die hole 18 by pushing it by the punch 11 to form the groove 3 for generating dynamic pressure on the inner diameter face 16 of the sleeve 15. Due to the grooving part 14 of the punch 11 being correctly formed in advance, the groove accuracy of the sleeve 15 is improved to improve the quality of the fluid bearing. The mass production is achieved because of the working being quickened.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of manufacturing a fluid bearing having a shaft and a sleeve, and having a hydrodynamic groove on the bearing inner diameter surface of the sleeve.

(Prior art) Conventionally, as shown in FIG. 1, a hydrodynamic bearing having a groove for generating dynamic pressure has a shaft 1 rotatably inserted into the inner diameter of a sleeve 2, and a dynamic pressure generated on the inner diameter surface of the sleeve 2. Generation groove 3
A lubricant is supplied to the cooperating surfaces of the shaft 1 and the sleeve 2, and when either the shaft 1 or the sleeve 2 rotates, the cooperating surfaces are lubricated by the pump action of the dynamic pressure generating groove 3. This generates pressure.

As a method for forming the dynamic pressure generating grooves 3 in the sleeve 2 made of a relatively soft metal material such as brass, there is a plastic working method using hard balls. For example, as shown in FIG. 7, a rotary pin 4 is provided coaxially and rotatably with the hole 5 of the sleeve 2, and a beam retainer 6 is coaxially and rotatably provided between the sleeve 2 and the rotary pin 4. retainer
6 has a plurality of holes 7 arranged symmetrically around the central axis.
A hard ball 8 is fitted into these holes 7 so as to be freely movable, giving a predetermined rotational speed and feed rate to the rotating pin 4, and this rotation causes the rotating pin 4 and the sleeve 2 to
The retainer 6 is given a predetermined rotation speed and feed rate so that the retainer 6 follows the balls 8 rolling between the balls 8 and the sleeve 2 is subjected to plastic working by the balls 8.

(Problems to be Solved by the Invention) However, in the plastic working method as described above, different rotational speeds must be given to the rotating pin 4 and the retainer 6, so the manufacturing equipment becomes complicated, and the rotating The cylindricity of the pin 4, the sphericity of the ball 8, or the retainer 6
The accuracy of the hole 7 and the accuracy of the depth of the dynamic pressure generation groove 3 to be machined are easily affected by the error in the feed speed of the rotating pin 4 and the retainer 6. Variations may occur. Such variations impair the rotational performance of the hydrodynamic bearing, and are therefore a major problem in the manufacturing method of this type of hydrodynamic bearing.

Therefore, in view of the above-mentioned points, it is an object of the present invention to provide a method for manufacturing a hydrodynamic bearing, which can reduce variations in grooves and simplify manufacturing equipment.

(Means for solving problems) The present invention solves the above problems with the following configuration.

That is, the method for manufacturing a hydrodynamic bearing of the present invention includes a punch having a grooved portion formed on the outer diameter surface of a plurality of protrusions formed to correspond to the shape of the groove of a hydrodynamic bearing with grooves for generating dynamic pressure. , while coaxially inserting the sleeve into the hole of the sleeve, positioning the sleeve in the axial direction with a punch, and coaxially pushing the sleeve through the hole of the die with an inner diameter smaller than the outer diameter of the sleeve. This forms grooves that generate dynamic pressure.

(Example) An example of the present invention will be described below based on FIGS. 2 to 6.

11 is a rod-shaped punch with one end formed with a small diameter,
A grooved portion 14 consisting of a plurality of protrusions 13 formed to correspond to the shape of the herringbone groove of a hydrodynamic bearing with grooves for generating dynamic pressure is provided on a part of the outer diameter surface 12 of the small diameter portion. . Reference numeral 15 denotes a sleeve made of a relatively soft brass alloy, and has an inner diameter d2 that is appropriately larger than an outer diameter D1 of the grooved portion 14 of the punch 11. 17 is provided with a hole 18 having an inner diameter dl smaller than the outer diameter D2 of the sleeve 15, and a taper 18a whose inner diameter continuously increases in the axially outward direction near both ends;
18b. The dice 17 are placed on a dice base 19.

Then, the grooved part 14 of the punch 11 is inserted into the IJ-button 15.
At the same time, the sleeve 15 is inserted coaxially into the die 17, and the sleeve 15 is positioned in the axial direction on the diameter difference step 11' of the punch 11, and the sleeve 15 is coaxially pushed through the hole 18 of the die 17 with the punch 11. A herringbone-shaped dynamic pressure generating groove 3 is formed on the inner diameter surface 16 by coining.

After passing through the hole 18 of the die 17, the inner diameter d2 of the sleeve 15 becomes thicker than the dimension when passing through the die due to springback. can be removed from the grooved portion 14 of the punch 11.

If the amount of springback is small, the sleeve 15 can be heated appropriately to thermally expand and removed from the grooved portion 14 of the punch 11. This removal method is suitable for a sleeve made of brass alloy, which has a larger coefficient of thermal expansion than tool steel, which is the material of the punch 11.

In the embodiment, the case where the dynamic pressure generating groove is of a herringbone type has been described, but the present invention is also applicable to other types of dynamic pressure generating groove.

(Effects of the Invention) The present invention provides a punch with a grooved portion formed on the outer diameter surface consisting of a plurality of protrusions formed in accordance with the shape of the groove of a hydrodynamic bearing with grooves for generating dynamic pressure. Dynamic pressure is generated on the inner diameter surface of the sleeve by coaxially inserting it into the hole, positioning the sleeve in the axial direction with a punch, and coaxially pushing the sleeve through the die hole with an inner diameter smaller than the outer diameter of the sleeve. Since this is a method of forming grooves, it is possible to form a grooved part consisting of multiple protrusions with high precision in accordance with the shape of the groove of a hydrodynamic bearing with a dynamic pressure generating groove in advance, and mold it into the sleeve. The accuracy of grooves formed can be improved.

In addition, it can be manufactured using simple equipment and at high speed.
Suitable for mass production of hydrodynamic bearings.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a hydrodynamic bearing with grooves for generating dynamic pressure according to the present invention, FIG. 2 is a cross-sectional view of a manufacturing apparatus for carrying out the manufacturing method of the present invention, and FIG. Fig. 4 is an enlarged sectional view of the main part of the punch used, Fig. 4 is a sectional view of the sleeve in an unprocessed state, Fig. 5 is an enlarged sectional view of the main part of the die used in the manufacturing device of Fig. 2, and Fig. 6 is a diagram showing grooves in the sleeve. FIG. 7 is a sectional view of a manufacturing apparatus showing the forming process, and FIG. 7 is a sectional view of a conventional manufacturing apparatus for forming grooves on the inner diameter of a sleeve. 1t---Punch 13---One protrusion 14---Groove processing part 15---Sleeve 17---Die 18---Die hole←---Dynamic pressure generation groove Figure 3 Figure 4 Figure 5 Figure 6 Funeral Figure 7

Claims (1)

[Claims] 1) Insert coaxially into the hole of the sleeve a punch whose outer diameter surface has a grooved part consisting of a plurality of protrusions formed to correspond to the shape of the grooves of a hydrodynamic bearing with grooves for generating dynamic pressure. At the same time, the sleeve is positioned in the axial direction with a punch, and the punch coaxially pushes the sleeve through a hole in a die having an inner diameter smaller than the outer diameter of the sleeve, thereby forming a hydrodynamic groove on the inner diameter surface of the sleeve. Production method