JP3485595B2 - Hydrostatic gas bearing spindle - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrostatic gas bearing spindle for introducing a high-pressure gas between a main shaft and a bearing to support the main shaft in a non-contact state. is there. [0002] Since a hydrostatic gas bearing supports a main shaft in a non-contact state by the pressure of high-pressure gas, it has a smaller friction loss than other bearing types and is suitable for a high-speed spindle. It is used for spindles in painting machines, grinders, small-diameter drilling machines, etc. FIGS. 3 and 4 show an example of a spindle using such a hydrostatic gas bearing. A hollow main shaft 2 housed in a housing 1 is connected to a journal bearing 3 and a flange 5 of the main shaft 2. It is supported in a non-contact manner with respect to the bearing surface by a double-sided opposed thrust bearing 4 sandwiched from both sides. [0004] The journal bearing 3 and the thrust bearing 4 are provided with air supply nozzles 7 and 8 which communicate with a gas supply path (not shown) provided in the housing 1, and a bearing clearance is provided between the air supply nozzles 7 and 8. 9 operates as a hydrostatic gas bearing by supplying a high-pressure gas to the main shaft 9 and supports the main shaft 2 in a non-contact manner in the radial direction and the thrust direction. On the outer peripheral surface of the flange 5 of the spindle 2,
A plurality of turbine blades 10 are formed at predetermined intervals in a circumferential direction, and a plurality of turbine blades 10 are configured to blow high-pressure gas toward the turbine blades 10 on a housing inner diameter surface 12 opposed to the turbine blades 10 via a small clearance 11. A nozzle 13 is formed. Further, a turbine exhaust passage 14 is provided in the housing 1, and the exhaust passage 14
1 communicates to the side. In the spindle having the above structure, high-pressure gas is introduced from the air supply nozzles 7 and 8 of the journal bearing 3 and the thrust bearing 4, and the main shaft 2 is supported in a non-contact manner from the turbine nozzle 13 to the turbine blade 10. When the high-pressure gas is blown toward the main shaft 2, a rotational force is applied to the main shaft 2 to rotate at high speed.
The gas blown to the turbine blade 10 has a small gap 1
1 to the turbine exhaust passage 14 and the housing 1
Is discharged to the outside. However, in the above-described spindle, the high-pressure gas blown out from the turbine nozzle 13 generates a small gap 1 between the main shaft 2 and the housing 1.
1, the turbine exhaust may not always reach the exhaust passage 14 quickly and may not be exhausted efficiently. For this reason, the outlet pressure of the turbine nozzle 13 becomes higher than the atmospheric pressure, so that the supplied high-pressure gas cannot expand sufficiently at the nozzle outlet, and the driving force of the turbine is reduced. . Accordingly, the present invention solves the above-mentioned problems, and can quickly exhaust the exhaust gas of the turbine with a simple structure.
It is an object of the present invention to provide a hydrostatic gas bearing spindle capable of improving the driving force of a turbine. [0010] In order to solve the above-mentioned problems, the present invention provides an inner diameter of a housing in which a nozzle for a turbine is formed , facing a turbine blade through a small gap. The surface is provided with a recess communicating with the turbine exhaust passage ,
The structure adopted was to quickly exhaust the exhaust from the bottle . As described above, by providing the recess on the inner diameter surface of the housing, the turbine exhaust is smoothly discharged to the exhaust passage, and the high-pressure gas blown out from the nozzle expands sufficiently to the atmospheric pressure. Thus, the driving force of the turbine is improved. 1 and 2 show a hydrostatic gas bearing spindle according to an embodiment. Since the basic structure and operation of this spindle have been described in the section of the prior art, the same parts will be denoted by the same reference numerals and description thereof will be omitted, and only the features of the embodiment will be described. As shown in the figure, a turbine blade 1 of a main shaft 2 is provided.
A plurality of turbine nozzles 13 are formed at predetermined intervals in a circumferential direction on the housing inner diameter surface 12 facing the housing 0, and a recess 15 is formed between each of the nozzles 13. One end of each of the recesses 15 is open to a turbine exhaust passage 14 provided in the housing 1.
It communicates with the outside of the housing 1 through the exhaust passage 14. In the above structure, the high-pressure gas blown out from the turbine nozzle 13 flows into the recess 15 and the minute gap 1.
1 and smoothly flows into the exhaust passage 14 and is quickly discharged to the outside of the housing. Therefore, the pressure at the outlet of the turbine nozzle 13 rapidly decreases, and the high-pressure gas supplied from the nozzle 13 expands sufficiently to the atmospheric pressure at the nozzle outlet, so that the driving force of the turbine is greatly increased. Can be. In the above embodiment, the turbine blade 10 is integrally formed on the surface of the main shaft 2. However, the turbine blade is provided on a member separate from the main shaft connected to the main shaft, and the turbine is driven via the member. The force may be transmitted to the main shaft. As described above, according to the present invention, the concave portion communicating with the exhaust passage is provided at the front side of the turbine nozzle, and the exhaust of the turbine is quickly discharged, so that the driving force of the turbine is improved. This has the effect of enabling high-speed rotation of the spindle.

[Brief description of the drawings] FIG. 1 is a longitudinal sectional view showing a spindle according to an embodiment. FIG. 2 is a sectional view taken along line II-II of FIG. FIG. 3 is a longitudinal sectional view showing a conventional example. FIG. 4 is a sectional view taken along line IV-IV in FIG. 3; [Explanation of symbols] 1 Housing 2 spindle 3 Journal bearing 4 Thrust bearing 6 Gas supply passage 7, 8 Air supply nozzle 9 Bearing clearance 10 Turbine blade 11 minute gap 12 Housing inner diameter 13 Turbine nozzle 14 Exhaust passage 15 recess

Claims (1)

(57) [Claim 1] An air supply nozzle for supplying a high-pressure gas through a main shaft inside a bearing member incorporated in a housing and supplying a high-pressure gas to a bearing gap between the main shaft and the bearing member. Formed into members,
A plurality of turbine blades arranged in the circumferential direction are provided on the main shaft, and a turbine nozzle for blowing high-pressure gas toward the turbine blades is formed on an inner diameter surface of a housing opposed to the turbine blades via a small gap. and, in the housing, the externally pressurized gas bearing spindle having a turbine exhaust passage communicating with the small gap, before Symbol housing, the inner diameter surface to face each other with a small gap in a turbine blade, before Symbol turbine exhaust passage Tar is provided a recess which communicates
A hydrostatic gas bearing spindle wherein the exhaust of the bottle is quickly discharged .