JPH0518919B2 - - Google Patents

Description

Detailed Description of the Invention (Technical Field) This invention relates to a hydrostatic gas bearing that can significantly reduce the frictional force involved and support a rotating shaft with high precision. The present invention relates to a method for manufacturing a porous hydrostatic gas bearing in which gas is ejected through a bearing member made of

(Background technology) To support the rotating shafts of high-speed turbo machines, nuclear reactors, space equipment, precision measuring instruments, etc. with high accuracy by reducing frictional force, the rotating shafts are supported in a floating state by gas pressure. Hydrostatic gas bearings are widely known.
As one of these hydrostatic gas bearings, the bearing member is made of porous material such as sintered metal to uniformly disperse the flow of air ejected into the bearing part and obtain a bearing with better performance. There are porous hydrostatic gas bearings made of solid materials. 1 and 2 show this type of porous hydrostatic gas bearing, with FIG. 1 showing a radial bearing and FIG. 2 showing a thrust bearing. That is, in a radial bearing, a cylindrical bearing member 3 made of a porous material is coupled to the inside of a cylindrical air supply chamber 2 having an air supply inlet 1 with both ends bent inward. A rotating shaft 4 is inserted inside a member 3, and the rotating shaft 4 is floated by the static pressure of compressed gas, such as compressed air, which is ejected into a gap 5 between the inner circumferential surface of the bearing member 3 and the outer circumferential surface of the rotating shaft 4. State supported. or,
In the thrust bearing shown in FIG. 2, a disc-shaped bearing member 3a is provided opposite to a disc 6 fixed to the end of the shaft 4, and the side of the bearing member 3a opposite to the disc 6 is supplied with air. It is covered with a chamber 2a and is supplied with air from the air supply inlet 1, and supports the thrust force applied to the rotating shaft 4 by the static pressure of the gas ejected into the gap 5a between the bearing member 3a and the disc 6. It is.

In such a static pressure gas bearing, in order to obtain a predetermined performance, the bearing member 3,
Gap 5, 5a between 3a and rotating shaft 4 or disk 6
The thickness of the bearing members 3, 3a must be accurately finished as designed, and the permeability, which indicates the degree to which gas can pass through the bearing members 3, 3a, must be made as designed. However, it is difficult to obtain a completely homogeneous material for the bearing members 3 and 3a due to variations in particle size of the sintered metal material that constitutes them, uneven pressure during pressure molding, unevenness during material filling, etc. It is inevitable that differences in permeability will occur even in bearing members that are molded.

Therefore, in order to obtain a predetermined permeability, we conducted ``Research on the practical application of porous gas bearings'' (Page 35 of the preprint of the academic lectures at the Autumn Conference of the Japan Society of Precision Machinery, October 1962) or ``Research on porous hydrostatic gas bearings'' ( As with the bearing reported in the March 1971 Tohoku Branch Lecture Proceedings of the Japan Society of Precision Machinery Engineers, the bearing surface of the bearing member 3 is machined by turning, grinding, etc. As shown in Figure 3, the edge of the hole that opens on the bearing surface is deformed inward to create burrs 7, 7, which partially clog the hole, and the resulting throttling effect reduces the permeability. I was thinking of making some adjustments. However, when adjusting the penetration rate using such a method, it is difficult to obtain the desired penetration rate with one-time turning or grinding, and turning and other operations are repeated until the desired penetration rate is achieved. The dimensions of the bearing member 3 with the bearing member 3 change variously, and in the case of a radial bearing, when a rotating shaft of a certain thickness is inserted inside the bearing member 3, the gap 5 between the bearing member and the rotating shaft becomes different. , in the case of a thrust bearing, the disc 6 and the bearing member 3a
The gaps 5a between the bearings and the bearings become unequal, making it impossible for either bearing to maintain its performance as a bearing. In order to maintain the performance of the bearing regardless of the difference in the dimensions of the bearing member 3, in the case of a radial bearing, the rotating shaft 4 must be machined to match the bearing member 3 after completion, or a large number of shafts with different diameters must be machined. It is necessary to prepare a rotating shaft in advance and select an appropriate one from among them for use.In addition to adjusting the permeability of the bearing members 3 and 3a to the design value through trial and error, manufacturing of the gas bearing is done. Not only is this extremely troublesome and difficult to perform in mass production, but even in the case of small quantity production, the processing dimensions at the time of completion cannot be predicted, resulting in poor production efficiency. In order to solve this problem, there is an invention (Japanese Patent Publication No. 56-19498) in which two types of bearing materials with different permeability are overlapped to make the permeability the same as the designed value with a constant size. It is difficult in itself to find a bearing material whose permeability matches the design value.
Even if it is possible to always keep the rotating shaft to a constant size, it is difficult to improve overall production capacity.

For this reason, as shown in FIG.
The solid powder 9 mixed with an adhesive and a solvent is applied to partially clog the small holes opening in the bearing surface 8, and the gas permeability is adjusted to a predetermined value. There is also an invention related to porous hydrostatic gas bearings (Japanese Patent Application No. 145501/1986), but this invention can reduce the permeability of the bearing member when it is too high, but in the opposite case, that is, the permeation rate can be reduced. If the ratio is too small, it is not possible to widen the fine air passages in the bearing member and increase the permeability. However, as shown in FIG. 3, when the surface of a sintered metal bearing member is ground flat, burrs 7, 7 are generated on the metal particles 19, 19 that make up this bearing member. It frequently occurs that the burrs 7, 7 block the openings of the fine air passages, reducing the permeability of the bearing member to a lower than desired value. In this way, bearing members with too many burrs 7, 7 and whose penetration rate is too low will not have a high penetration rate even after repeated turning and grinding, and such bearing members will be discarded as defective products. As a result, the yield becomes extremely poor.

(Objective of the present invention) The present invention eliminates the above-mentioned disadvantages, makes it possible to easily manufacture a bearing member having desired dimensions and permeability, and also provides low cost and high performance because there are extremely few defective products. It is an object of the present invention to provide a method for manufacturing a porous hydrostatic gas bearing that can obtain a stable gas bearing.

(Structure of the present invention) The method for manufacturing a porous hydrostatic gas bearing of the present invention includes first processing the bearing surface of a bearing member made of a porous metal material by machining such as turning, grinding, or wrapping. The dimensions of the bearing member are processed to the desired values, and burrs are formed at the openings on the bearing surface side of the fine air passages to make the permeability of the bearing member smaller than the desired permeability. The bearing member is immersed together with the electrode in an electrolytic solution, and a portion of the burr is eluted to adjust the permeability of the bearing member to a desired value.

(Embodiments of the present invention) Next, the present invention will be explained in more detail while explaining the illustrated embodiments.

FIG. 5 shows how a radial bearing is manufactured by the method of the invention. The bearing member 3 is made of a metal porous material and has an inner diameter turned to a predetermined size and burrs 7, 7 as shown in FIG. 3 are formed on the bearing surface 8. It is fixed to the inner peripheral side of the electrolytic cell 10 and immersed in the electrolytic solution 11 in the electrolytic cell 10. When turning the bearing surface 8 to finish the inner diameter to a predetermined size, the shape and sharpness of the blade used can be appropriately selected to make it easier to generate burrs 7, and to achieve the desired penetration rate of the bearing member 3. Keep it smaller than the value of . A round electrode rod 12 is inserted into the center of the bearing member 3 in the electrolytic solution 11, and the electrode rod 12 is connected to the negative side of a DC power source 15 via an ammeter 13 and a variable resistor 14. On the other hand, the metal air supply chamber 2 is connected to the positive side of this DC power supply 15. 16 is a bearing member 3 fixed inside the air supply chamber 2
This is a voltmeter for measuring the voltage applied between the electrode rod 12 and the electrode rod 12.

When the bearing member 3 is immersed together with the electrode rod 12 in the electrolytic solution in this manner and a current is passed from the bearing member 3 toward the electrode rod 12, a portion of the bearing member 3 is eluted into the electrolytic solution. At this time, the current density is highest at the edge of the burr 7 located at the edge of the aperture opening 17 on the bearing surface 8 side of the bearing member 3, so the amount of elution at this edge is particularly large. , the aperture aperture 17
The area of will gradually increase. Furthermore, even if the burr 7 is in contact with the adjacent metal particle 19, there is a minute gap between the edge of the burr 7 and the particle 10, so the burr 7 elutes from the edge and forms an aperture opening. be done. Therefore, if the current supply is stopped when the permeability of the bearing member 3 reaches a desired value, a gas bearing having desired dimensions and a desired permeability can be obtained. At this time, the amount of metal eluted from the portions other than the burrs 7, 7 is negligibly small, so the electrolytic treatment does not change the inner diameter of the bearing member 3. Further, the bearing surface 8 of the cylindrical bearing member 3 extends over the entire length of the electrode rod 12.
Since the distances to the burrs are equal, the elution of the burrs 7, 7 proceeds uniformly over the entire bearing surface 8, and the permeability of the bearing member 3 becomes uniform throughout the bearing member 3 when viewed macroscopically.

The amount of current required for the permeation rate to reach the desired value can be easily determined experimentally, but if the permeation rate becomes too large due to excessive current application,
The penetration rate can also be reduced by the method of the prior invention shown in FIG.

Next, FIG. 6 shows the state in which a thrust bearing is manufactured by the method of the present invention. A cylindrical bearing member 3a, which has been ground to a predetermined size so that the permeability is smaller than a desired value, is connected to a metal dish-shaped air supply chamber 2.
a, and is immersed in the electrolytic solution 11 together with the disk-shaped electrode plate 18. Bearing surface 8 of bearing member 3a
and the electrode plate 18 are held parallel to each other, and a current is uniformly passed from the bearing member 3a to the electrode plate 18. The rest is the same as in the case of manufacturing the radial bearing described above, so a redundant explanation will be omitted.

In addition, in the above-mentioned embodiment, the bearing member 3,
Before electrolytically treating the bearing surface 8 of 3a, each bearing member 3, 3a was fixed to a metal air supply chamber 2, 2a, and the positive side of the DC power supply 15 was connected to this air supply chamber 2, 2a. This DC power supply is directly connected to the bearing members 3, 3a.
The bearing members 3, 3a having a desired permeability after electrolytic treatment may be fixed to the air supply chambers 2, 2a.

(Effects of the present invention) Since the method for manufacturing a porous hydrostatic gas bearing of the present invention is configured and carried out as described above, it is easy to obtain a bearing member having a predetermined permeability and a predetermined size, and the performance is A superior gas bearing can be obtained at a low cost.

[Brief explanation of the drawing]

1 and 2 are vertical cross-sectional views showing porous hydrostatic gas bearings, with FIG. 1 showing a radial bearing and FIG. 2 showing a thrust bearing. Fig. 3 is an enlarged sectional view of the bearing surface after turning or grinding, Fig. 4 is an enlarged sectional view of the bearing surface with fixed powder attached, and Fig. 5 is an enlarged sectional view of the bearing surface after turning or grinding. FIG. 6 is a vertical sectional view showing the state in which a bearing is manufactured, and FIG. 6 is a longitudinal sectional view showing a state in which a thrust bearing is manufactured. 1... Air supply inlet, 2, 2a... Air supply chamber, 3, 3
a... Bearing member, 4... Rotating shaft, 5, 5a... Gap, 6... Disc, 7... Burr, 8... Bearing surface, 9
... solid powder, 10 ... electrolytic cell, 11 ... electrolyte, 12 ... electrode rod, 13 ... ammeter, 14 ...
Variable resistance, 15...DC power supply, 16...Voltmeter,
17...Aperture aperture, 18...Electrode plate, 19...Metal particles.

Claims (1)

[Claims] 1. Cutting the bearing surface of a bearing member made of porous metal material to obtain the desired dimensions, and forming a burr at the opening on the bearing surface side of the minute air passage in the bearing member. The air passage is constricted by the burr to reduce the permeability of the bearing member to a desired value or less, and then the bearing member is connected to the positive side of a DC power source and placed in an electrolyte together with the electrode connected to the negative side of the DC power source. A method for manufacturing a porous hydrostatic gas bearing, in which the permeability of the bearing member is made to a desired value by immersing the bearing member in water to elute some of the burrs and increase the opening area of the air passage.