Method for producing a dynamic fluid bearing with high rotation precision and high hardness

Abstract

A method for manufacturing bearing components of high precision and hardness supporting fluid dynamic-pressure comprises the steps of: (1) selecting at least one rotary component provided with a predetermined surface pattern for supporting a distribution of fluid dynamic-pressure; (2) forming an opaque and hard amorphous diamond (DLC, a-D) film (or nano-crystalline diamond film) on the pivotal surface of the component by physical vapor deposition (PVD). Thereby the pivotal surfaces of the rotary component and the pattern thereon can have excellent hardness, wearing resistance, rotational stailbity and durability under repeated urging of dynamic fluid pressure.

Description

FIELD OF THE INVENTION [0001] The present invention relates to methods for manufacturing bearing components supporting fluid dynamic-pressure, more particularly to a method for manufacturing bearing components of high precision and hardness for dynamic pressure fluids, in which physical vapor deposition is utilized to coated an amorphous diamond film of hardness approaching 80-100 GPa over a pivotal interface or a patterned surface on which a fluid pressure is distributed of a bearing component. BACKGROUND OF THE INVENTION [0002] Dynamic-pressure fluid bearings are used in high-speed driving units of hard disk drives and CD-ROM, which mainly comprise a sleeve, a spindle and a fluid, such as air and lubricating oil, injected therebetween. The dynamic-pressure fluid bearings of the prior art are categorized into dynamic-pressure fluid radial bearings and dynamic-pressure fluid thrust bearings. According to various necessities, the pivotal interface between the sleeve and the spindle o...

AI Technical Summary

Benefits of technology

[0007] Accordingly, the primary objective of the present invention is to provide a method for manufacturing bearing components, such as sleeve and spindle, of high precision and hardness supporting fluid dynamic-pressure, which components are hard-wearing and durable so that the space between the spindle and the sleeve can maintain perfectly round after high speed rotation for a long time. And, further, it is convenient to produce such components.

[0008] The method disclosed by the present invention is coating a layer of amorphous diamond over bearing components by physical vapor deposition, whereby the connecting surfaces or the carved pattern of those components may have hardness of 80-100 GPa, density of 3.0-3.2 g / cm3 and coefficient of friction of 0.1. The hardness of the film can be twice more than that of the diamond like carbon film containing hydrogen (DLC, a-C:H) of the prior art, which is 10-50 GPa as shown in Table 2. Therefore, the film made by the present invention is highly wear-resisting, durable and adhesive, capable of protecting a trough against the dynamic pressure produced by high-speed fluid passing through. And, therefore, the components coated with the film can maintain low vibration, low wiggling, low noise, high durability and perfect roundness even after high-speed rotation for an extended period of time, especially when the components undergo an initial startup or a stall.

[0009] It is a further objective of the present invention that chemical vapor deposition is used to form a film of crystallize diamond of diamond-level hardness, attaining 80-100 GPa (as shown in Table 2). However, the coating temperature of this method should be higher (<600° C.) and therefore is more expansive; this method is suitable for producing thicker films.

[0010] The methods described above are for making bearing components of high precision and hardness supporting fluid dynamic-pressure and therefore suitable for making the sleeves and spindles of the motors used in personal computers, notebook computers, servers, printers, hard disk drive and CO-ROM. The method disclosed by the present invention can be applied in mass production and therefore of low production cost.

Problems solved by technology

However, in the start-up period and in low-speed rotation, the spindle and the sleeve may contact and produce metal powder in the fluid, causing a change in fluid viscosity and therefore degrading the lubricating fluid.

The durability and precision of the bearing components may also degrade.

However, the protective effect is not substantial.

But, the films have yet to match the industrial requirements of precision, hardness and low cost.

However, the coating methods have a hydrogen problem that enhances water absorptivity of the films, increasing the frictional coefficient and thus decreasing the adhesive force of the films.

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