JPH0371944A - Method for forming dynamic pressure-producing groove on dynamic pressure bearing - Google Patents

Abstract

PURPOSE:To highly accurately work a dynamic pressure-producing groove through press working by bringing a groove producing a desired dynamic pressure and a punch provided with a projection having the same shape as it into contact with each other on a bearing stock of porous metal having a limited porosity. CONSTITUTION:A disk bearing stock W of sintered alloy of iron-carbon-copper having a porosity 3-10% is set on a machine base 10 and as soon as the punch 11 having the projection in the same shape as a helical groove on the front end surface is pressed in at the prescribed pressure, it is vibrated in a prescribed frequency in the direction of an arrow 12 to form an accurate spiral groove 5 on the stock W. When a herringbone shape groove 1 is formed on the external peripheral surface of a cylindrical sleeve, a porous cylindrical sleeve stock Wa in the same way as before-mentioned is fitted closely to a shaft 13. Then, the punch 11a provided with a herring bone shape projection is pressed on the sleeve stock Wa at a prescribed pressure and as a prescribed frequency is given in the direction of an arrow the punch 11a is moved and the stock Wa is rotated to accurately copy and form the herringbone shape groove.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for forming dynamic pressure generating grooves that support loads in the radial direction and thrust direction of a dynamic pressure bearing.

(Prior art) For example, as shown in FIG.
A radial type hydrodynamic bearing with a herringbone-shaped groove 1 of approximately 25 μm in diameter, or a thin groove on one of the contact surfaces of the rotating disk 3 and the stationary disk 4 placed opposite it, as shown in FIG. There is a thrust bearing with a large number of wound grooves 5, and its use is expanding, mainly in audio equipment.

In order to form such grooves for generating dynamic pressure, a solid metal material is used as the bearing material. For example, a film with a groove-shaped pattern formed thereon is coated with a rotating shaft 3 or fixed roller whose surface is coated with photosensitive paint. A photo-etching method (for example, see Japanese Patent Publication No. 49351/1983) is employed in which the film is brought into close contact with a disc, exposed to light, the film is removed, and the exposed surface is electrochemically corroded.

(Problems to be Solved by the Invention) Although the above photoetching method can form an accurate groove shape, the process is long and the work is complicated;
This will increase costs.

Therefore, it is also possible to perform groove processing using a precision press. However, in this case, the excess material pressed by the punch moves to the periphery of the groove and bulges up, which prevents the desired groove shape from forming and has a negative impact on bearing performance, making it impossible to obtain a good bearing. For example, in the thrust bearing shown in Fig. 7, the bottom surface of the groove 5 and the shoulder 6 left between the grooves
The field rises by 15 μm from a few μm field. Moreover, the entire center portion has a convex shape. When the chips 6 are processed by polishing, etc., the grooves in the center become shallow, and the grooves become shallower toward the outer periphery, making it impossible to use them as grooves for generating parallel dynamic pressure, and the polishing work is extremely troublesome. , it takes a long time to work. For this reason, groove forming by pressing was impossible.

(Means for Solving the Problems) The present invention provides a punch in which protrusions of the same shape as the hydrodynamic grooves of a desired shape are provided at predetermined positions of a porous metal bearing material having a porosity of 3 to 10%. A method of forming a power generation groove at a predetermined position of the bearing material by applying vibrations and pressure at a predetermined frequency and pressure for a short period of time. This makes it possible to process with high precision.

The reason why the porosity is set to 3 to 10% is because if it is less than 3%, excess meat cannot be absorbed sufficiently, and if it exceeds 10%, dynamic pressure will escape and the pressure cannot be increased.

(Function) A porous metal bearing material with a porosity of 3 to 10% is used, and a punch with a desired groove shape is used to press the material and apply vibrations of a predetermined frequency and amplitude. The excess material pressed by the punch is absorbed into the many holes, so there is no bulge to the outside, and the shape of the punch is accurately transferred to the groove in a very short time, forming a dynamic pressure generating groove.

(Example) Next, the present invention will be explained with reference to the drawings. FIG. 1 is a schematic diagram of a device for forming dynamic pressure generating grooves 5 formed on the dynamic pressure generating surface of a dynamic pressure thrust bearing as shown in FIG. A disk-shaped bearing material W made of a sintered alloy is set on the machine stand 10, and a spiral groove (
At the same time, a punch 11 equipped with a protrusion (not shown) having the same shape as that shown in Fig. After 5 seconds, Figure 5.
As shown in FIG. 6, the bottom surface and shoulder 6 of the groove 5 were flat, and an extremely accurate spiral groove 5 with a groove depth of 5 μm was formed.

When forming the herringbone-shaped groove 1 as shown in FIG. 3 on the outer peripheral surface of the cylindrical sleeve, the apparatus shown schematically in FIG. 2 was used. The cylindrical sleeve material Wa is a porous member made of brass with a porosity of 10%, and is fitted onto the shaft 13 so that the gap is close to zero to back up the sleeve material, and is placed opposite to the punch lla. let The punch has a flat plate with a herringbone-shaped protrusion (not shown) on the surface that contacts the curved surface of the sleeve material. After positioning the shaft 13 and the sleeve material Wa, the punch lla is brought close to the sleeve material Wa, and
While pressing with a pressure of 0 kg/am'' and applying vibrations with a frequency of 2 Hz and an amplitude of 10 μm in the direction of arrow 12 for 0.8 seconds,
The punch lla was moved in a direction perpendicular to the plane of the paper like a rack, and the sleeve material Wa was rotated. As a result, herringbone-shaped grooves with a groove depth of 10 μm were accurately transferred and formed.

In addition, for example, in order to form dynamic pressure generating grooves in stainless steel sintered alloy with a porosity of 3%, the punch pressure is 120 k
g/ctm", a vibration frequency of 30 Hz, an amplitude of 5 μm, and an excitation time of 5 seconds, a groove with a groove depth of 5 μm was formed accurately and quickly.

(Effects) As mentioned above, the present invention uses bearing materials with a porosity of 3 to 1.
Since the grooves for generating dynamic pressure were formed by pressing 0% porous metal at a predetermined frequency and pressure, the excess metal pressed by the press is absorbed into the pores and builds up at the bottom of the groove and on the shoulders. There is no climbing and grooves are formed with great precision. In addition, it is extremely efficient because it can be carried out in a short time of less than 60 seconds, which greatly contributes to cost reduction.

In addition, since the porosity has an appropriate value, there is no problem of the dynamic pressure escaping and the pressure not being able to rise, and it is possible to provide a dynamic pressure bearing with performance comparable to conventional products.

[Brief explanation of drawings]

Fig. 1 is a schematic diagram of the device used in the present invention, Fig. 2 is a schematic diagram of another embodiment, Fig. 3 is a sectional view of a general radial bearing with herringbone grooves, and Fig. 4 is ( stomach>
(b) is a plan view showing the groove shape; FIG. 5 is a plan view showing the spiral groove formed according to the present invention; FIG. FIG. 5 is a cross-sectional view taken along the line OA, and FIG. 7 is a view corresponding to FIG. 6 of a conventional method for forming grooves on a solid metal material. 1...Dynamic pressure generation groove 6...Dynamic pressure generation groove 11...Punch 12...Punch W...Porous metal material Wa...〃

Claims (1)

[Claims] A punch with protrusions of the same shape as the hydrodynamic grooves of the desired shape is placed in contact with a porous metal bearing material with a porosity of 3 to 10% at a predetermined position, and then a predetermined frequency and pressure are applied for a short period of time. Additionally, a method for forming a dynamic pressure generating groove in a dynamic pressure bearing, comprising forming a dynamic pressure generating groove at a predetermined position of the bearing material.