JPH0478364B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an apparatus for manufacturing a grooved fluid bearing having a shaft and a sleeve, and having dynamic pressure generating grooves on the outer peripheral surface of the shaft.

Conventional Structure and Problems Conventionally, a grooved hydrodynamic bearing consists of a sleeve 2 rotatably inserted around the outer circumference of a shaft 1, and dynamic pressure generating grooves formed on the outer circumference of the shaft 1, as shown in Fig. 1. A lubricant 3 is applied to the cooperating surface of the shaft 1 and the sleeve 2, and as either the shaft 1 or the sleeve 2 rotates, a dynamic pressure generating groove 1A is provided.
Pressure is generated by the pumping action of

As a method of machining this type of dynamic pressure generating groove 1A on the shaft 1, there is a method of plastic working using a ball harder than the shaft 1, but conventionally, as a specific manufacturing apparatus for this, the apparatus shown in Fig. 2 is used. be. As shown in the figure, a hard rotating collar 5 is rotatably provided on the same axis as the shaft 1 that is the workpiece, and a guide pipe 4 is coaxially and rotatably provided between the rotating collar 5 and the shaft 1. The pipe 4 has a plurality of guide holes 4A, 4B arranged symmetrically around the axis 1, into which a plurality of hard balls 6A, 6B are fitted in a freely rolling manner.

At this time, the rotating collar 5 is placed at the outer peripheral position of the shaft 1.
While giving the rotational speed of W _p and the feed rate of V _p ,
This rotation causes the guide pipe 4 to follow the balls 6A, 6B that revolve between the rotating collar 5 and the shaft 1 at a rotational speed of W _i and V _i
axis 1 by balls 6A and 6B with a feed rate of
The dynamic pressure generating groove 1A is plastically worked.

However, in this conventional manufacturing method, the rotating collar 5 and the guide pipe 4 must be given different rotational speeds W _p and W _i, respectively, which complicates the manufacturing equipment, and the inner diameter of the rotating collar 5 is not tapered. Although it is desirable that the pipe be straight and straight, it is inevitable that there will be some variation in diameter of 2 to 3 μm, and at this time, a slight discrepancy occurred in the feed speeds V _p and V _i of the rotating collar 5 and guide pipe 4. Sometimes, the diameter of the rotating collar 5 changes at the part where the balls 6A, 6B touch, and the balls 6A, 6B slightly change in diameter.
6B moved in and out of the guide holes 4A and 4B, and the depth of the dynamic pressure generating groove 1A to be machined sometimes varied by several μm. This variation was a particularly large drawback since it impairs the rotational performance of the bearing.

OBJECTS OF THE INVENTION The present invention solves the above-mentioned conventional drawbacks, and reduces variations in the depth of dynamic pressure generating grooves, enables highly accurate processing, and simplifies manufacturing equipment.

Structure of the Invention The present invention includes a plurality of guide holes distributed on a circumference perpendicular to and coaxial with the center of a guide pipe, a hard collar press-fitted into a position covering the guide holes, and a hard collar press-fitted into a position covering the guide holes. It has a plurality of hard balls inserted into the shaft, and is combined so that the inner diameter of the collar is slightly smaller than the total sum of the outer diameter of the shaft and the diameter of the two balls, and the outer circumference of the shaft It has the characteristic that dynamic pressure generating grooves can be easily formed with high precision.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. The guide pipe 7 has a plurality of guide holes 7A, 7B arranged on a circumference perpendicular to and coaxial with the center of the guide pipe 7, and a hard ball 9A is inserted into the guide holes 7A, 7B. ,9B
is inserted or lightly press-fitted, and a collar 8 is press-fitted onto the outer periphery of the guide pipe 7 so as to close the guide holes 7A, 7B. Further, the inner diameter of the collar is selected so that the sum of the inner diameter of the collar 8 and the diameters of the two balls 9A and 9B is slightly smaller than the outer diameter of the shaft 1. In this state, when a rotation speed W and a feed speed V are applied to the guide pipe 7 coaxially with the shaft 1 and near the outer periphery of the shaft, the dynamic pressure generating groove 1A is formed by plastic working by the balls 9A and 9B.

When machining a herringbone-type dynamic pressure generating groove 1A as shown in FIG. 1, the feed speed V of the guide pipe 7 is It can be formed by switching the rotational speed W in the opposite direction without changing it.

In the present invention, the dynamic pressure generating groove 1A
In forming the guide pipe 7, only the guide pipe 7 needs to be fed and rotated, so the manufacturing equipment becomes simple. Further, since the collar 8 is fixed to the guide pipe 7, the inner diameter of the collar 8 does not change at the balls 9A, 9B unlike in the conventional case, so there is no variation in the depth of the dynamic pressure generating groove. This was an especially important issue because the depth of this groove is shallow, about 10 μm, and variations in depth of about 2 μm can have a big impact on the performance and reliability of hydrodynamic bearings.

The balls 9A, 9B may be inserted into the guide holes 7A, 7B so as to be able to roll freely, or may be press-fitted and fixed, but it is better to press-fit and fix the balls 9A, 9B to prevent the balls 9A, 9B from out of roundness. Since there is no influence, there is less variation in groove depth.

Effects of the Invention As described above, according to the present invention, by attaching a collar and a hard ball to the guide pipe and applying rotation and feed speed on the outer periphery of the shaft, dynamic pressure can be easily generated with high precision without variation in groove depth. Since grooves can be machined, its practical value is great.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a grooved hydrodynamic bearing according to the present invention, FIG. 2 is a cross-sectional view of a conventional manufacturing apparatus for forming grooves on the outer circumference of a shaft, and FIG. 3 is a cross-sectional view of a grooved hydrodynamic bearing according to an embodiment of the present invention. 1 is a cross-sectional view of a manufacturing apparatus for forming a 1...Shaft, 1A...Dynamic pressure generating groove, 2...Sleeve, 7...Guide pipe, 7A, 7B...Guide hole, 8...Collar, 9A, 9B...Ball.

Claims (1)

[Claims] 1. A guide pipe 7 having a plurality of guide holes 7A, 7B, a plurality of balls 9A, 9B inserted into the guide holes 7A, 7B, and the ball 9.
A, 9B has a cylindrical collar 8 circumscribing the guide pipe 7 and fixed to the guide hole 7.
A, 7B and the balls 9A, 9B are located on a circumference perpendicular to and coaxial with the central axis of the guide pipe 7, the balls 9A, 9B and the collar 8 are made of a harder material than the shaft 1, and the balls 9A, 9B are The circumferential diameter of the shaft 1 is smaller than the outer diameter of the shaft 1, and the inner diameter of the guide pipe 7 is set larger than the outer diameter of the shaft 1. An apparatus for manufacturing a grooved hydrodynamic bearing that processes a dynamic pressure groove 1A on the outer periphery of the shaft 1.