JPH08547U - Rolling bearing - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a rolling bearing having corrosion resistance and low noise. [Structure] In stainless steel, there are many large carbides due to the eutectic of carbon and chromium. The bearing made of stainless steel has poor acoustic characteristics as compared with a general bearing due to the presence of the giant carbide. In order to eliminate the giant carbide, it is necessary to reduce the content of chromium, but on the other hand, if the content of chromium is reduced too much, the corrosion resistance decreases. The present invention is a martensitic stainless steel having a chromium content such that corrosion resistance is obtained even in an environment such as dew condensation in the atmosphere.
While forming the outer ring, the rolling elements are made of bearing steel, paying attention to the fact that the corrosion resistance of the rolling elements is secured by the lubricant in the bearing. As a result, even if the large carbides remain on the inner and outer rings, the large carbides do not come into contact with each other between the rolling contact surfaces, so that the influence on the acoustic characteristics is reduced. Bearing according to the present invention (diagram 1)
Shows almost the same good acoustic characteristics as a bearing formed of only bearing steel (diagram 2).

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rolling bearing used in an environment where corrosion resistance and low noise are required, such as a bearing used in a spindle motor of a hard disk drive (HDD).

[0002]

[Prior art]

 The bearing is generally formed of bearing steel, but a corrosion resistant material such as martensitic stainless steel is used especially when used in an environment where corrosion resistance is required. However, this corrosion resistant material is a steel containing carbon and chromium, and there are many large carbides formed by the eutectic of carbon and chromium. Bearings using this corrosion-resistant material have poor workability due to the presence of giant carbides, and the precision of steel balls cannot be improved.Therefore, the acoustic characteristics are less than those of bearings using general bearing steel. It is known to be inferior.

[0003]

[Problems to be solved by the device]

 Conventionally, bearing materials used in environments where low noise and corrosion resistance are required at the same time, such as bearings used in hard disk drives, have been contradictory to low noise and corrosion resistance. In many cases, it was decided by comparing the required degree of characteristics. That is,

(1) When the requirement for low noise is particularly strict and the corrosion resistance can be ignored to some extent, a bearing steel is used.

(2) Stainless steel is used when the corrosion resistance is particularly demanding.

(3) If both low noise and corrosion resistance are strict requirements, a bearing steel coated with corrosion resistance is used.

Among these, according to the one shown in (3), both characteristics can be satisfied at the same time, but the man-hour for plating treatment is extra, and the bearing processing after plating treatment is difficult. There was a point.

Therefore, the present invention is to provide a rolling bearing having the contradictory characteristics of low noise and corrosion resistance.

[0009]

[Means for Solving the Problems]

 The present invention is characterized in that the bearing components constituting the inner and outer raceways are made of martensitic stainless steel, and the rolling elements interposed between the inner and outer raceways are made of bearing steel. Providing rolling bearings.

[0010]

[Action]

 To eliminate the large carbides present in stainless steel, it is necessary to reduce the chromium content. On the other hand, if the chromium content is reduced too much, the corrosion resistance will decrease. The present invention forms a bearing component that constitutes the inner and outer raceways from a martensitic stainless steel having a chromium content that is sufficient to provide corrosion resistance even in an environment such as dew condensation in the atmosphere. Is made of bearing steel. The acoustic characteristics of bearings are greatly affected by the accuracy (roughness) of raceways and rolling elements, and particularly by the accuracy of rolling elements. Although the accuracy of the inner and outer raceways deteriorates due to the large carbides, the acoustic characteristics are improved by forming the rolling elements from bearing steel. This is because even if the giant carbides remain in the bearing components that form the inner and outer raceways, there is no giant carbides in the rolling elements, so there is no contact between the giant carbides between the rolling contact surfaces. This is because the effect on the acoustic characteristics is reduced. On the other hand, since the rolling elements are substantially protected from corrosion by a lubricant such as grease, there is no reduction in corrosion resistance due to the rolling elements being made of bearing steel.

[0011]

Embodiments Embodiments of the present invention will be described below.

FIG. 1 shows a precision shaft unit to which the present invention is applied. This precision shaft unit holds a shaft 1 having two rows of raceway grooves 1a formed on the outer peripheral surface, an outer ring 5 fitted into the raceway groove 1a via rolling elements 3, and rolling elements 3 at equal intervals around the circumference. It is composed of a cage 4, a non-contact seal 6 mounted on the non-opposing side end of the outer ring 5, and a coil spring 16 mounted via a spring seat 15 between the outer rings 5. The shaft 1 and the outer ring 5 which form the inner and outer raceways are made of martensitic stainless steel having a chromium content of 12 to 14%, and the rolling elements 3 are made of bearing steel.

FIG. 2 shows the results of noise measurement performed on a deep groove ball bearing in which the inner and outer rings are made of martensitic stainless steel and the rolling elements are made of bearing steel. In the figure, line 1 shows the above bearings, line 2 shows the bearings using only bearing steel, and line 3 shows the results of noise measurement for bearings with inner and outer rings and rolling elements made of martensitic stainless steel. Indicates. As is clear from the measurement results, the rolling bearing according to the present invention exhibits almost the same good acoustic characteristics as those using only bearing steel.

[0014]

[Effect of device]

 The present invention secures the corrosion resistance of the bearing by forming the bearing components forming the inner and outer raceways from martensitic stainless steel. Furthermore, by forming the rolling elements from bearing steel, even if there is a large amount of carbide remaining in the bearing components that make up the inner and outer raceways, it is possible to prevent the large carbides from contacting each other between the rolling contact surfaces. I chose Therefore, according to the present invention, the corrosion resistance and the low noise property of the bearing can be secured at the same time.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of the present invention.

FIG. 2 is a diagram showing a noise measurement result.

[Explanation of symbols]

 1 shaft 1a raceway groove 3 rolling element 5 outer ring

Claims (1)

[Scope of utility model registration request] 1. A bearing component constituting the inner and outer raceways is made of martensitic stainless steel, and rolling elements interposed between the inner and outer raceways are made of bearing steel. Rolling bearing.