JPS6017537Y2 - Split type hydrodynamic bearing sleeve - Google Patents

Description

[Detailed Description of the Invention] This invention relates to the improvement of a hydrodynamic grooved hydrodynamic bearing mainly used in equipment that requires high speed rotation, low noise, and high precision.

For example, as shown in Figure 1, dynamic pressure type grooved hydrodynamic bearings, which have been widely used in the bearings of micro motors and the spindles of audio equipment, have a cylindrical hole that is perpendicular to the axis of the inner peripheral surface. Sleeve 1 with multiple pressure generation (Hilling Bone Mizo) 2a, 2a ... with multiple pressure occurrence (Hilling Bone Mizo), which has a bending form of a tilt direction on the same plane
A shaft 4a is fitted onto the inner circumferential surface 3a of a, a lubricant is interposed between the shaft 4a and the inner circumferential surface 3a, and pressure is generated in the lubricant by rotation of the shaft 4a to support the shaft. Although the structure is
The curved pressure generating grooves 2a, 2a provided on the inner circumferential surface 3a of the sleeve are formed by injection molding, which is normally used for molding this type of parts made of plastic or plastic alloys. Methods of melting and solidifying the grooves using a forming tool, such as compression molding and compression molding, or forming them plastically can be considered, but in both methods, after forming, interference between the bent grooves causes problems during forming. This method is currently used in combination with electrochemical methods to melt the grooves of the workpiece and form it.1 Pressure generation grooves 2a, 2a... are formed using the photoetching method.
However, this method is completely unsuitable for mass production because it is complicated, requires a large number of steps, and is difficult to rationalize. Although this type of hydrodynamic bearing has excellent performance, Due to its high cost, it has the drawback of not being widely popular.

This invention compensates for the above-mentioned drawbacks of conventional products and provides a grooved hydrodynamic bearing sleeve that is inexpensive and of uniform quality.

Next, the hydrodynamic bearing sleeve of this invention is shown in Figures 2 and 3.
To explain the typical embodiment shown in the figure, FIGS. 2 and 3 are sectional views of the main parts of the first embodiment and the second embodiment of the fluid bearing sleeve according to this invention, respectively, and the reference numeral in the figure 1 and 2 are sleeve forming members 11, respectively.
, 11... and 21, 21... are pressure generation grooves, 3 and 4 are sleeves 1 and 2, respectively.
The inner peripheral surfaces 5 and 6 are joint surfaces of the combined sleeves 1 and 2, respectively.

First, the first embodiment of this invention shown in FIG. 2 will be described. The sleeve forming members 1 and 2 are separately formed cylindrical sleeves, and the inner peripheral surfaces 3 and 4 are provided with pressure generating grooves 11. , 11... and 21.2
1... is formed, but the shape of the grooves of the sleeve forming members 1 and 2 is different from that of the sleeve forming member 1.
Regarding 2 and 2, a constant spiral-shaped groove of the lead with completely opposite twisting directions is formed by cutting through the ends of both sleeves 1 and 2, and during molding, a special tool is used to form the groove. By rotating the tool in one direction after forming, the tool can be removed from the grooves formed in the sleeves 1 and 2, and the grooves 11, 11, . . .
... and 21, 21... have completely opposite twisting directions, but other specifications are the same.

Sleeve forming members 1 and 2 formed by a special tool in this way are joined at flat surfaces 5 and 6 so that inner circumferential surfaces 3 and 4 are concentric, and pressure generating grooves 11, 11 and 21, 21 are located at the ends. After the two sleeve forming members 1 and 2 are assembled so that the positions of the parts match each other and are completely fixed as one body, they can be completely used as one sleeve having a plurality of bent grooves. The shafts are then fitted together and used as a hydrodynamic bearing.

Figure 3 shows a second embodiment of this invention, in which the grooves 11, 11 and 21.21 of the two sleeve forming members are formed by spirals in opposite directions with a constant lead, similar to the first embodiment. The sleeve-forming members 1 and 2 have a groove shape that allows the tool to be removed from the formed groove by rotating the special tool used in the process in opposite directions. are joined and fixed together at the planes 5 and 6, but unlike the first embodiment, the pressure generation grooves 11, 11... and 21, 21... are connected to the planes 5 and 6. Since the phase of the groove during molding based on 6 is different from that in the first embodiment, the two sleeve forming members 1 and 2 are joined and fixed to form one sleeve. Even after the pressure generation groove 11.11...
. . , 21, 21, . . . , there is a difference in the position of the end portions, and the grooves do not completely form two curved pressure generating grooves.

As mentioned above, in both the first and second embodiments of this invention, the pressure generating groove has a shape that can be extracted from the molded groove of the sleeve by rotating a special molding tool. Grooving of individual sleeve forming members is much more efficient and less costly than the conventional one-photoetching method.

Furthermore, since the same tool is used to continuously form the grooves, the shape accuracy of the grooves becomes uniform and the variation in quality is reduced compared to the conventional method.

Further, as shown in the second embodiment, sleeves 1 and 2, which have mutually offset positions of the end portions of the pressure generating grooves, are joined and fixed to be integrated, as shown in the first embodiment. It has been experimentally confirmed that there is almost no difference in performance compared to a sleeve in which the positions of the ends of the grooves of the two sleeves match each other. Furthermore, when forming one sleeve, as shown in the first embodiment, it is somewhat troublesome to completely align the phases of the curved pressure-generating grooves, so the second embodiment As usual, even if the end parts do not match, there is almost no difference in performance, so the second embodiment is easier to combine, and the cost can be reduced even more than the first embodiment. It is.

Note that in both the first and second embodiments, no special molding is performed on the joints between the inner circumferential surfaces 3 and 4 of the sleeves 1 and 2, but in order to avoid cracks at the joints and slight diameter differences. In some cases, the joining portion of the inner circumferential surfaces 3 and 4 is chamfered to a large extent.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part of a conventional hydrodynamic grooved fluid bearing, and FIGS. 2 and 3 are sectional views of main parts of an embodiment of a hydrodynamic bearing sleeve according to this invention. In the drawings of the embodiment, numerals 1 and 2 are sleeve forming members, 3 and 4 are the inner peripheral surfaces of the sleeves 1 and 2, respectively, 5 and 6 are the joined planes of the sleeves 1 and 2, respectively;
11 and 21 are pressure generating grooves in sleeves 1 and 2, respectively.

Claims (3)

[Scope of utility model registration request] (1) The inner peripheral surface of the cylindrical hole of the sleeve held in the housing has a plurality of pressure generating grooves whose inclination directions are reversed on the same plane perpendicular to the axis of the inner peripheral surface, and the inner peripheral surface A hydrodynamic grooved fluid bearing sleeve has a structure in which a lubricant is interposed between the mating shaft and the shaft or the housing rotates, and pressure is generated by rotation of the shaft or the housing. A split type fluid bearing sleeve characterized in that it is formed by integrally joining a plurality of hollow cylindrical sleeve forming members each having a spiral pressure generating groove with a constant lead and having their end surfaces abutted against each other. . (2) Utility model registration claim 1 in which the position of the end of the pressure generating member coincides with the contact surface of the sleeve forming member
Split type hydrodynamic bearing sleeve as described in . (3) The split type fluid bearing sleeve according to claim 1, wherein the positions of the ends of the pressure generating members do not match on the contact surface of the sleeve forming member.