JPH11125253A - Gas bearing - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably support a shaft, and prevent seizure by forming twisted spiral grooves in the inverse direction on outer peripheral surfaces corresponding to both end parts of a bushing of the shaft so as to restrain an air current exhausted from both ends of a clearance by unidirectional rotation of the shaft. SOLUTION: A rightward twisted triangular crest-shaped spiral groove 11 is formed on an outer peripheral surface corresponding to a tip part of a gas bearing 3 of a shaft 7, and a leftward twisted triangular crest-shaped spiral groove 11 is formed on an outer peripheral surface corresponding to a rear end part. When the shaft 7 rotates, an air current trying to proceed inside from the outside of the gas bearing 3 is generated in a clearance (a) by the action of both side spiral grooves 11 and 12, and this restrains an air current trying to flow outside from the inside of the clearance (a) by flowing in from a small hole 6. Therefore, pressure in the clearance (a) increases, and consumption of pressurized air flowing in from the small hole 6 is reduced, and even if there is a slight pressure variation in supply air, the shaft is stably supported, and seizure can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bearing cylinder having a large number of small holes penetrating from an outer periphery to an inner periphery. A shaft is fitted with a small gap therebetween, and pressurized gas is injected into the gap from the small hole. The present invention relates to a gas bearing that supports the shaft by floating the shaft from a bearing cylinder.

[0002]

2. Description of the Related Art Gas bearings such as those described above are often used to support a shaft rotating at a high speed, such as a spray gun for a rotary atomizing type coating.

[0003]

However, gas bearings need to supply a large amount of pressurized gas such as compressed air, which consumes a large amount of energy, and the shaft vibrates due to pressure fluctuations of the supplied gas. There was a risk of burning.

[0004]

SUMMARY OF THE INVENTION The present invention, as a means for solving such a problem, is directed to an air flow discharged from both ends of a gap on outer peripheral surfaces corresponding to both ends of a shaft bearing cylinder. Helical groove twisted in the opposite direction so that the rotation of the shaft is suppressed in one direction, the gap can be maintained at a high pressure even if the supply of pressurized gas is small, and energy consumption is reduced. In addition, the shaft can be stably supported even if there is some pressure fluctuation in the supplied gas, and there is an effect of preventing image sticking.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to the accompanying drawings.

In FIG. 1, reference numeral 1 denotes a spray gun main body, a holder 2 is attached to the tip thereof, and a gas bearing 3 is attached to the holder 2, and the gas bearing 3 is driven to rotate at a high speed by an air turbine 9. A hollow shaft 7 is supported, and a bell-shaped atomizing head 10 is attached to the tip of the shaft 7.
The liquid paint supplied through the hollow of the nozzle passes along the inner surface of the atomizing head 10 and reaches the edge of the tip, from which it is atomized by the action of centrifugal force and electrostatic field and applied to the object to be coated (not shown). It is supposed to.

The gas bearing 3 is a bearing in which pressurized air fed from a supply passage 4 formed in the spray gun body 1 is fitted with a shaft 7 with a small gap a as shown in an enlarged view in FIG. Pressurized air flows from a number of small holes 6 formed in the cylinder 5 into the gap a to support the shaft 7 in a floating state, and the axial direction is the same from both sides of a flange 8 formed on the shaft 7. As described above, the air is supplied in a floating state by supplying the pressurized air.

Although the above is a conventionally known rotary atomizing type coating spray gun, in this embodiment, the tip of the gas bearing 3 of the shaft 7 that rotates clockwise as viewed from the right side in FIGS. A right-handed triangular helical groove 11 is formed on the outer peripheral surface corresponding to the portion, and a left-handed triangular helical groove 12 is formed on the outer peripheral surface corresponding to the rear end portion.
Are formed.

Therefore, when the shaft 7 rotates, the gas bearing 3 is inserted into the gap a by the action of the spiral grooves 11 and 12 on both sides.
An airflow that flows from the outside to the inside of the gap a is generated, and this tries to suppress the airflow that flows in from the small hole 6 and flows out of the gap a to increase the pressure in the gap a. The consumption of the pressurized air flowing from the hole 6 can be reduced, and the shaft can be stably supported even if there is some pressure fluctuation in the supplied air, so that seizure can be prevented.

The present invention can be applied to gas bearings other than the above-mentioned rotary atomization type spray gun for coating.

[Brief description of the drawings]

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

FIG. 2 is an enlarged sectional view of a main part thereof.

[Explanation of symbols]

 3: Gas bearing 5: Bearing cylinder 6: Small hole 7: Shaft 9: Air turbine 10: Atomizing head 11, 12: Spiral groove a: Gap

────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 27, 1997

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0008

[Correction method] Change

[Correction contents]

The above is a conventionally known spray gun for rotary atomization type coating , but in the present embodiment,
A shaft 7 that rotates clockwise as viewed from the right side of FIGS.
The right-handed triangular helical groove 11 is formed on the outer peripheral surface corresponding to the front end portion of the gas bearing 3, and the left-handed triangular helical groove 1 is formed on the outer peripheral surface corresponding to the rear end portion.
2 are formed.

Claims (1)

[Claims] A shaft is inserted into a bearing cylinder having a large number of small holes penetrating from the outer periphery to the inner periphery with a small gap therebetween, and pressurized gas is injected into the gap from the small hole. In the gas bearing configured to float and support the bearing from the bearing cylinder, air flows discharged from both ends of the gap are formed on the outer peripheral surfaces of the shaft corresponding to both ends of the bearing cylinder by rotating the shaft in one direction. A gas bearing with a spiral groove twisted in the opposite direction to suppress it.