JPS63111315A - Ceramics ball bearing - Google Patents

Abstract

PURPOSE:To make it possible to form an outer race, balls and a rotating shaft of ceramics, by forming a ball raceway groove on the rotating shaft and directly supporting the rotating shaft. CONSTITUTION:The ceramics ball bearing is a single row radial ball bearing using a counter bore type outer race 4 and balls 3. The outer race 4 is formed by eliminating one of shoulders 41 forming a raceway groove. The outer race 4, the balls 3 and a rotating shaft 1 are all formed of ceramics. No inner race is provided. The rotating shaft 1 is formed with an arcuate ball raceway groove 2, and is directly supported by the balls 3. Accordingly, the outer race 4 of the counter bore type to be separated is not fixed in position relative to the rotating shaft 1, but is movable in a direction of its back surface. Thus, all the advantages of the bearing formed of ceramics material may be owned.

Description

[Detailed description of the invention]

TECHNICAL FIELD The present invention relates to a rolling bearing made of ceramics. [Conventional technology] New ceramic materials that have become available as a result of recent advances in ceramics technology have, in addition to the properties of conventional ceramics such as heat resistance and chemical resistance,
Taking advantage of its wear resistance and low coefficient of friction, it is used for things such as skid rails in heating furnaces. On the other hand, as various industrial and consumer machines become smaller and more sophisticated, the bearings that support rotating shafts are required to be smaller and lighter, and to withstand high loads and high rotations. Efforts are being made to meet this demand through improvements in special steel used as bearing materials and advances in processing technology, but the results are still not fully satisfactory.

[Problems to be solved by the invention]

An object of the present invention is to take the current state of the art as described above one step further and provide a bearing made of ceramics that has better performance than conventional steel bearings. [Means for solving the problem] The first and basic aspect of the ceramic ball bearing of the present invention will be described with reference to the drawings.
As shown in the figure, it is a single row radial ball bearing using an outer ring 4 and balls 3 of a counterbore type, that is, one of the shoulders 41 of the groove forming the raceway is removed.
The outer ring 4, the balls 3, and the rotating shaft 1 are all made of ceramic, the inner ring is omitted, and the rotating shaft 1 is provided with an arcuate ball raceway groove 2 to directly support the rotating shaft 1. This ceramic ball bearing may be of an angular contact type as shown in FIG. 2, and a straight line connecting the contact points of the balls 3 and the outer ring 4 may have a contact angle indicated by θ with respect to the radial direction. In use, for example, as shown in FIG. 3, two rows of ball raceway grooves 2 may be provided on the rotating shaft 1, and two outer rings 4 may be assembled so that their front faces face each other. Of course, if the operating conditions are such that a force is exerted on the rotating shaft 1 and the outer ring 4 in a direction that moves the center of each other, that is, the rotating shaft does not move in the front direction of the outer ring, and the outer ring does not move in the rear direction, is optional. In a second aspect of the present invention, in addition to the first aspect, as shown in FIG. 4, a positioning groove 6 is provided on the back surface of the outer ring of the rotating shaft 1, and a positioning groove 6 is provided therein as shown in FIG. Attach the ting ring 5. In this case as well, the bearing may be of an angular contact type and may have a contact angle at the contact point between the ball 3 and the outer ring 4. In this aspect, even if the outer ring is moved by the force that moves it in the rear direction, the locating ring 5 restricts the movement and maintains the bearing configuration. It can be treated in the same way as a radial bearing. Suitable ceramic materials include alumina, zirconia, silicon nitride, and other fine ceramics, and may be selected depending on the intended use of the bearing product. Each part is manufactured by adding an appropriate binder to fine ceramic powder, press-molding it, machining the resulting green (intermediate product), and sintering it. When it is necessary to fix the locating ring 5 to the outer ring 4, an appropriate adhesive may be used. [Function] Conventional steel bearings were assembled by shrink fitting, taking advantage of the metal's large coefficient of thermal expansion. Ceramic materials cannot be assembled using conventional methods because they do not have the same thermal expansion as metals and have the smallest possible elastic deformation. The inventors discovered that a ceramic material powder molded using a suitable binder can be precisely machined, and that the machining process results in sintering with a nearly constant degree of sintering, resulting in a high degree of compactness even after sintering. It was found that accuracy was maintained. Using the technology established by the inventors, it is possible to manufacture highly accurate outer rings, balls, and rotating shafts from ceramics. The ceramic ball bearing of the present invention has a selected assembly method, and the outer ring is of a counterbore type, so that the rolling elements can be constructed smoothly. The outer ring green can be easily formed by pressing. In general, since the inner ring was omitted and the rotating shaft was directly supported, the diameter of the outer ring was reduced, and the overall size and weight could be made smaller. The counterbore type separable outer ring is not fixed in position with respect to the rotating shaft, but is movable toward the rear side thereof. Therefore, in the first invention, if necessary, two bearings are combined facing each other to prevent the bearing from deviating from side to side. In the second invention, a locating ring is attached to stabilize the position of the outer ring. Ceramic locating rings may move with the positioning groove due to slight movement in the axial direction of the rotating shaft;
There is no problem with rotation, and there is no problem with wear. The angular contact type prevents the rotating shaft from moving toward the back surface of the outer ring, and also withstands slight cart thrust in that direction. [Example 1] A small diameter bearing having the structure shown in FIG. 1 was manufactured from alumina. The dimensions of the main parts are as follows. Diameter of rotating shaft 1.5# Outer diameter of outer ring 4.0 Width of outer ring 2.5H Diameter of ball pitch circle 1.7m Diameter of inscribed circle 1.0m Diameter of circumscribed circle 2.4InIn ball diameter
Greens for each of seven 0.7 m x 7 greens were manufactured taking into account 17% sintering, and after sintering, the shoulders of the outer ring grooves were polished at an angle of inclination of 60' with respect to the axis and assembled. [Example 2] A small diameter bearing having the structure shown in FIG. 4 was manufactured using zirconia. The dimensions of the main parts are as follows. Diameter of rotating shaft 3.0m Outer diameter of outer ring 7.0# Width of outer ring 3.0m (3.4m including locating ring) Diameter of ball pitch circle 3.2Nn Diameter of inscribed circle 2.5m Circumscribed Circle diameter: 3.9 m Ball diameter: 0.7 m x 14 locating rings Thickness: 0.4 m Outer diameter: 7.0 m Effects of the Invention The ceramic bearing of the present invention can enjoy all the advantages of bearings made of ceramic materials. , which is significantly more durable than conventional steel bearings.
Suitable for applications where maintenance is difficult.
It also has the same properties as ceramics, such as chemical resistance, acid resistance, and salt water resistance, making it useful for various chemical plants and ships. It goes without saying that it is also heat resistant, so
It is useful as a bearing used at temperatures where lubricating oil cannot be used, or at even higher temperatures. In particular, the present invention has a bearing outer diameter of 9# as shown in the embodiment.
It has the right meaning when applied to bearings of a scale equivalent to miniature bearings, and is useful as bearings for small equipment such as micro motors and various types of VTRs.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a basic aspect of the ceramic ball bearing of the present invention. FIG. 2 is a similar cross-sectional view showing an angular contact type embodiment of the embodiment of FIG. FIG. 3 shows an example of use in which the bearing shown in FIG. 1 is combined with two outer rings facing each other. FIG. 4 is a sectional view showing another embodiment of the ceramic ball bearing of the present invention, that is, an example of one having a locating ring, and FIG. 5 is a front view of the locating ring used therein. 1... Rotating shaft 2... Ball raceway groove 3... Ball 4... Outer ring 5... Locating ring 6... Positioning groove Patent applicant Hisashi Kobayashi Agent Patent attorney Suga SofuFigure 1Figure 2Figure 3Figure 4Figure 5

Claims (6)

[Claims] (1) A single-row radial ball bearing using a counterbore type outer ring and balls. The outer ring, balls, and rotating shaft are all made of ceramics, and a ball raceway groove is provided on the rotating shaft to directly support the rotating shaft. Ceramic ball bearings are characterized by: (2) The ceramic ball bearing according to claim 1, which has a contact angle at the contact point between the ball and the outer ring. (3) A ceramic ball bearing according to claim 1, wherein two rows of ball raceway grooves are provided on the rotating shaft, and two outer rings are assembled so that their front faces face each other. (4) A single-row radial ball bearing using a counterbore type outer ring and balls, in which the outer ring, balls, and rotating shaft are all made of ceramics, and a ball raceway groove is provided on the rotating shaft to directly support the rotating shaft. This ceramic ball bearing is further characterized in that a positioning groove is provided on the back surface of the outer ring of the rotating shaft, and a ceramic locating ring is attached thereto to prevent the outer ring from moving toward the back surface. (5) The ceramic ball bearing according to claim 4, which has a contact angle at the contact point between the ball and the outer ring. (6) A ceramic ball bearing according to claim 4, wherein two rows of ball raceway grooves are provided on the rotating shaft, and two outer rings are assembled so that their front faces face each other.