JPS6249351B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a method for forming dynamic pressure generating grooves in a shaft body for a hydrodynamic bearing.

For example, the shaft of a hydrodynamic bearing with grooves for generating dynamic pressure, which has been conventionally used in micro motors, audio equipment, etc., has a cylindrical shaft 1a, as shown in Fig. 1.
Dynamic pressure generating grooves 2a, 2 having a bent shape on the outer peripheral surface of the
However, the groove has a special shape and is difficult to form mechanically, so conventionally, the shape of the non-formed part of the groove was formed using a combination of electrochemical methods. Print the outer circumferential surface of the shaft 1a with anti-corrosion ink and corrode the non-printed part by etching to form grooves for generating dynamic pressure, or print the shaft 1a on a printing mold of a special printing device. There are two methods, such as printing the shape of the non-forming part on the outer peripheral surface of the shaft body 1a by rotating it once while in contact with each other, and molding it by etching as described above, but the former method is complicated and requires many steps. Although the latter process is highly efficient, it has the disadvantage that the print joint is easily distorted due to the weight of insufficiently cured ink during one revolution of the shaft. Ori,
It has not yet been put into practical use because the shape must be corrected after printing.

The present invention compensates for the above-mentioned drawbacks of the conventional methods, and provides a method for forming dynamic pressure generating grooves with high efficiency and stable quality, without insufficiently cured parts at the printed joints.

Next, the method for forming dynamic pressure generating grooves according to the present invention will be explained with reference to a typical embodiment shown in FIG. Reference numeral 1 is a shaft, 2 is a printing mold, 3 is an ink supply device, 4 is ink, and 5 is an ultraviolet ray.

A resin printing mold with holes in the shape of the desired dynamic pressure generation groove, leaving the outer circumferential surface of the shaft intact as a non-molded part, is used to form a thin mesh-like printing screen. The shaft body is held by a shaft body and is moved in accordance with the rotation of the shaft body while coming into contact with the outer peripheral surface of the shaft body, and the corrosion-resistant ink is supplied to the shaft body 1 through the printing mold 2 by an ink 4 supplying device 3.
The rotation of the shaft body 1 prints a desired shape on the outer peripheral surface.

Further, as shown in the figure, ultraviolet rays 5 are irradiated from the opposite side of the outer peripheral surface of the shaft 1 from the contact part with the printing mold 2, and the printing ink 4 uses ultraviolet curing ink. When the first printing part reaches the opposite side of the contact part between the shaft body 1 and the printing mold 2 due to the rotation of the shaft, it is irradiated with ultraviolet rays 5, and the ink 4 is cured in an extremely short period of time. Shaft body 1
As the rotation progresses and the first printing section returns to its original position, the last printing is done almost at the same time, and when printing is completed around the entire circumference of the shaft, the ink from the first and last printing will overlap somewhat. However, as mentioned above, the ink of the first printing is cured by being irradiated with ultraviolet rays 5 while the shaft body 1 is rotating, and there is no deformation of the shape due to uncured ink as in the conventional case. The troublesome work of correcting the distortion of the groove shape due to overlapping printing, which has been a problem, is almost unnecessary.

Further, the irradiation position of the ultraviolet ray 5 is the printing mold 2 of the shaft body 1.
The shaft body 1
Since the irradiation light is blocked by the rays and does not reach the contact area between the shaft 1 and the printing mold 2, the ink being printed will not be hardened by the irradiation, and the printing operation itself will not be affected at all. There isn't.

As mentioned above, in this invention, there is no concern that the shape of the printing joint due to the rotation of the shaft body 1 will be distorted, and the ink during printing will not harden during the operation, making it possible to print in large quantities with high efficiency. Therefore, it is possible to significantly reduce the cost.

In this embodiment, ultraviolet rays are used as the irradiated light, but the invention is not limited to this, and infrared rays can also be used.

[Brief explanation of the drawing]

FIG. 1 is an external view of a conventional hydrodynamic bearing shaft with grooves for generating dynamic pressure, and FIG. 2 is an explanatory diagram showing a method of printing grooves using this method. In the figure, numeral 1 is a shaft, 2 is a printing mold, 3 is an ink supply device, 4 is ink, and 5 is an ultraviolet ray.

Claims (1)

[Claims] 1 Rotate the shaft once while contacting the printing mold of the desired shape, print the shape of the non-formed part of the shape of the dynamic pressure generation groove on the outer peripheral surface of the shaft with anti-corrosive ink, In a method for forming a hydrodynamic pressure generating groove in a shaft body for a hydrodynamic bearing in which a groove is formed by corroding a non-printing part, the first printing is performed at a position other than the contact area with the printing mold of the dynamic pressure generating groove in the shaft body. The ink in the first printed part corresponding to the joining part of the printing is cured while printing other parts by rotation of the shaft, and the groove shape is created by joining the printed parts with uncured ink. A method for forming dynamic pressure generating grooves characterized by preventing collapse of the grooves.