JPH0214652Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to a hydrostatic bearing used in a rotating device for precision equipment.

[Conventional technology]

FIGS. 1 and 2 show a conventional example. Figure 1 shows
This is a multi-hole type static pressure bearing, and compressed fluid is supplied from the outside into the bearing gap between the rotating shaft 2 and the inner diameter surface of the bearing 1 through a large number of minute air supply holes 3 arranged on the inner diameter surface of the bearing 1. , rotatably supports the rotating shaft 2 without contact. This multi-hole hydrostatic bearing requires a large number of tiny air supply holes 3 with a diameter of about 0.1 to 0.5 mm, making drilling work extremely difficult.
There were drawbacks such as the air supply hole 3 being easily clogged.

In contrast, as shown in Fig. 2, the number of air supply holes 3a arranged on the inner diameter surface of the bearing 1a is reduced to less than half, and a shallow circumferential groove 4a passing through the air supply holes 3a is provided, thereby eliminating the drawbacks shown in Fig. 1. Hydrostatic bearings with circumferential grooves have been devised to reduce the impact and increase bearing rigidity. In this case, it is necessary for performance to make the circumferential groove 4a very shallow, for example, about 10 to 30 microns for a bearing clearance of 10 microns, and therefore the precision of groove machining is also strict. Therefore, when machining the circumferential groove 4a, the groove is usually processed by grinding or cutting after finishing the open inner diameter of the air supply hole 3a. There are problems in that the grooves 3a become clogged and burrs remain, which not only makes it difficult to process the grooves, but also severely limits the processing method itself.

[The problem that the idea aims to solve]

This invention enables groove machining without clogging micro-diameter air supply holes, and there are no restrictions on the groove machining method. Grinding, cutting, rolling, etc. can be freely selected, making it an easy and inexpensive machining method. The purpose of the present invention is to provide a hydrostatic bearing that can be adopted and improve bearing performance by increasing bearing rigidity and reducing flow rate with a small number of air supply holes.

[Means to solve the problem]

The hydrostatic bearing of this invention supports the rotating shaft without contact by supplying compressed fluid from the outside into the bearing gap formed between the rotating shaft and the bearing. It is characterized in that a shallow circumferential groove continuous in the circumferential direction of the rotating shaft is provided at least on the open side in the vicinity of the micro-diameter air supply hole array that acts as a throttle and is arranged on one side of the bearing surface.

In the case of a radial bearing, the outer diameter surface of the rotating shaft and the inner diameter surface of the bearing are mutually opposing bearing surfaces, and in the case of a thrust bearing, the rotating shaft and the radial direction surface of the bearing are mutually opposing bearing surfaces.

[Effect]

Since the circumferential groove is located near the air supply hole array, there is no risk of clogging the air supply holes during machining, and therefore restrictions on groove machining are relaxed and machining becomes easy.

The compressed fluid is first squeezed through a micro-diameter air supply hole,
Next, the air is constricted to the bearing gap from the air supply hole to the circumferential groove, and further constricted by the flow path resistance in the circumferential direction of the circumferential groove, and is supplied into the bearing gap. In the case of a conventional circumferentially grooved bearing (FIG. 2), the compressed fluid is throttled in at most two stages, the air supply hole and the circumferential groove, but with this invention, it is throttled in three stages.

〔Example〕

FIG. 3 shows a first embodiment of this invention, in which a small number of air supply holes 30 are arranged at equal intervals in the circumferential direction on the inner diameter surface of the bearing 10, and on both sides of the 30 rows of air supply holes,
A small amount (about 0.3 to 2 mm) downstream from the air supply hole 30
A shallow circumferential groove 40 having a depth of about 1 to 3 times the bearing clearance g is provided at a separated position.

With the above structure, the compressed fluid supplied from the outside is transferred due to the small diameter air supply hole 30, the bearing clearance g' from the air supply hole 30 to the circumferential groove 40, and the flow path resistance in the circumferential direction of the circumferential groove 40. It is narrowed down in three stages and supplied into the bearing gap g'', forming a hydrostatic bearing and rotatably supporting the rotating shaft 20 without contact.

4 to 6 show other embodiments of this invention, and FIG. 4 shows a double-row air supply type journal bearing, in which the inner surface of the bearing 11 is spaced apart in the axial direction. This is a case where one circumferential groove 41 is provided in each of the two rows of air supply holes 31 and 31 rows on the bearing open side, that is, on the downstream side of the flow of air supply.

FIG. 5 shows a journal bearing of the type in which air is supplied from the shaft, in which circumferential grooves 42 are provided on both sides of 32 rows of air supply holes on the outer diameter of the rotating shaft 22, and 12 indicates the bearing.

FIG. 6 shows an example of a thrust bearing, in which circumferential grooves 43 are provided on the inside and outside of the circumference of 33 rows of air supply holes arranged on the bearing surface, and 13 indicates the bearing. In addition,
Although not shown, in a thrust bearing whose inner diameter side is sealed, it goes without saying that a circumferential groove may be provided at one location outside (downstream side) of the circumferential supply hole array.

[Effect of idea]

In this invention, the circumferential groove is provided avoiding the air supply hole, so the groove can be machined without clogging the small diameter air supply hole. Further, there are no restrictions on the groove processing method, and grinding, cutting, rolling, etc. can be freely selected, and easy and inexpensive processing methods can be adopted. Furthermore, in the bearing of this invention, the compressed fluid
Since it is supplied into the bearing clearance which is narrowed in stages and has a large throttling effect, it is possible to improve the bearing performance by increasing the bearing rigidity and reducing the flow rate.

[Brief explanation of the drawing]

1 and 2 are perspective sectional views of conventional hydrostatic bearings, and FIGS. 3 to 6 are perspective sectional views of hydrostatic bearings showing embodiments of the present invention. 10, 11, 12, 13...Bearing, 20, 22
... Rotating shaft, 30, 31, 32, 33 ... Air supply hole, 40, 41, 42, 43 ... Circumferential groove.

Claims (1)

[Claims for Utility Model Registration] (1) In a hydrostatic bearing that supports the rotating shaft without contact by supplying compressed fluid from the outside into the bearing gap formed between the rotating shaft and the bearing, A shallow circumferential groove continuous in the circumferential direction of the rotating shaft is provided at least on the open side near the micro-diameter air supply hole that acts as a throttle, which is arranged on one side of the bearing surfaces facing each other with a gap between them. hydrostatic bearing. (2) The hydrostatic bearing according to claim 1, wherein the bearing surfaces are an outer diameter surface of the rotating shaft and an inner diameter surface of the bearing. (3) The hydrostatic bearing according to claim 1, wherein the bearing surface is a radial surface of the rotating shaft and the bearing.