JP2602345Y2 - Hydrostatic bearing device - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a structure of a hydrostatic bearing device which is held by pneumatic, hydraulic or hydraulic pressure in a bearing of a machine element.

[0002]

2. Description of the Related Art Conventionally, it has been known that a hydrostatic bearing device which is maintained by air pressure, water pressure, or oil pressure can obtain smooth characteristics without friction and wear.

For example, in the air slide shown in FIG. 6, a sliding body 1 is movably supported on a guide shaft 2, and air is ejected from the sliding body 1 into a gap therebetween. The sliding body 1 is obtained by fixing four base plates with bolts, and one of the base plates is formed with a plurality of pockets 21 in the base plate 20 as shown in FIGS. The pocket 21 is formed with a throttle hole 22 for ejecting air from the air passage hole 24 and a surface throttle 23 formed of a cross-shaped groove.
Has a bolt hole 25 for fastening with a bolt.

Generally, a plurality of pockets 21 must be formed in order to be supported by static pressure, and their internal pressures must be kept constant. However, a throttle hole 22 is formed between the air passage hole 24 and the pocket 21. Therefore, even if a pressure drop in one pocket 21 occurs due to an external force, the pressure drop on the air communication hole 24 side is suppressed to a small amount. Therefore, the other pocket 2
1 is also suppressed, and the support by the static pressure is continued. Therefore, in order to provide stable support, it is preferable that the number of the pockets 21 is as large as possible, and that the shapes of the apertures 22 and the surface apertures 23 are well-balanced.

[0005] The base plate 20 is integrally formed of ceramics such as alumina.
In the case of manufacturing the shape of No. 1, the depth of the surface stop 23 is given by
Since it is as small as about 0 μm, it has been performed by milling, etching, blasting (processing by abrasive grain injection), or the like. In addition, since the diameter of the drawn hole 22 is as small as about 100 μm and it is difficult to directly process the chip, a method in which a chip in which the drawn hole 22 is formed is separately prepared and fixed with an adhesive has been adopted.

[0006]

However, the conventional hydrostatic bearing device as described above has the following problems. 1) When the processing of the pocket 21 is performed by etching, blasting, or the like, the accuracy of about ± 20 μm is the limit, and the shape of the surface stop 23 cannot be formed with a precision of several μm in a well-balanced manner. For this reason, there is a problem that variation in partial rigidity when an eccentric load is applied is large, and the overall rigidity is reduced accordingly.

2) Further, when the pocket 21 is processed by milling, a very large number of man-hours are required, which has been a major factor in increasing the cost of the entire hydrostatic bearing device. Further, even in this case, the processing accuracy is limited to about ± 5 μm, and the variation in partial rigidity is large.

3) Further, in the manufacturing process of the hydrostatic bearing device, since the entire base plate 20 including the pockets 21 is integrally formed and the drawn holes 22 are separately formed and bonded, many steps are required. Cost was a factor. 4) If machining failure occurs even in one place in the pocket 21,
The entire base plate 20 was defective, and the yield was poor.

[0009]

SUMMARY OF THE INVENTION In view of the above problems, the present invention has, on a base plate having an air passage hole, a throttle hole and a surface throttle communicating with the throttle hole. A plurality of pocket members made of ceramics formed by press forming the restrictor are joined so that the restricting holes of each pocket member communicate with the air conducting holes, respectively, and the fluid supplied to the air conducting holes is passed through the restricting holes. The hydrostatic bearing device is formed by forming a hydrostatic fluid layer by jetting toward the guide shaft.

[0010]

According to the present invention, since the pocket member having the drawing hole and the surface drawing communicating with the drawing hole is manufactured separately from the ceramic by a press molding method, mass production can be easily achieved. Since the cost can be reduced, the shape of the throttle hole and the surface throttle can be standardized, the accuracy of the shape can be increased, and the number of pocket members can be easily increased. Variation in partial rigidity can be suppressed.

[0011]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
As shown in FIG. 6, the air slide according to one embodiment of the present invention includes a guide shaft 2 and a slide 1 supported on the guide shaft 2, and air is ejected from the slide 1 into a gap between the two. It is supposed to.

The sliding body 1 is composed of four base plates. FIG. 1 shows a perspective view of only the base plates. The base plate 10 includes a pocket member 11 and a base plate body 15.
In the pocket member 11, an aperture nozzle 12 and a surface aperture 13 are formed. Further, the base plate main body 15 is formed with an air conducting hole 16 and a bolt hole 17 for fastening to another base plate 10. further,
As shown in cross section in FIG. 2, the pocket member 11 is adhered to the base plate main body 15,
Are formed so as to communicate with each other.
Is supplied from the throttle hole 12.

In another embodiment, as shown in FIG. 3A, a concave portion 18 is formed in a portion of the base plate main body 15 where the pocket member 11 is to be mounted. Adhesion can facilitate positioning.

In another embodiment, as shown in FIG. 3B, the air conducting holes 16 of the base plate main body 15 are formed in a groove shape, and the end faces of the flanges 14 formed in the pocket members 11 are aligned. It is also possible to adopt a structure of bonding so as to cover the air conducting hole 16. With this structure, the base plate body 15 can be easily manufactured.

The material of the pocket member 11 is made of various ceramics such as alumina and zirconia, and a ceramic raw material powder is formed by a press molding method. If formed, it can be manufactured easily and with high precision. The base plate body 15 is also preferably made of ceramics, and is cast into a relatively large product, but is simple in shape and easy to manufacture.

As described above, by manufacturing the pocket member 11 as a separate body, the manufacturing is easy, the accuracy can be improved, and the yield can be improved.

In the above embodiment, the air slide in the linear direction shown in FIG. 6 is shown. However, the same structure can be applied to an air bearing in the rotational direction.
For example, as shown in FIG. 4, a pocket member 11 having a throttle hole 12 and a surface throttle 13 is formed in a sector shape, and the pocket members 11 are arranged adjacent to each other in an arc to form a hydrostatic bearing in a thrust direction of a rotating shaft. Can be configured. As shown in FIG. 5, the pocket member 11 provided with the aperture hole 12 and the surface aperture 13 is formed in a curved surface (tile shape), and the pocket members 11 are arranged adjacent to each other in a cylindrical shape, so that the rotating shaft is formed. Radial static pressure bearing can also be configured.

Experimental Example Here, a base plate 10 shown in FIGS. 1 and 2 was prototyped as an aerostatic bearing device of the present invention, and an air slide was assembled.
As a comparative example, a conventional air slide using the base plate 20 shown in FIGS. 7 and 8 was prepared, and an experiment for comparing the performance was performed. In each case, the guide shaft and sliding body are made of alumina ceramics, and the guide shaft cross section is 60 × 6
0mm, the width of the sliding body is 150mm, and the supply air pressure is 4k
The magnitude of the rigidity of each portion on the upper surface of the sliding body when g / cm ² was measured.

Table 1 is a partial stiffness table of an air slide (Comparative Example 1) in which a pocket has been worked by blasting, and Table 2
7 is a partial rigidity table of an air slide (Comparative Example 2) in which a pocket is machined by milling. From these results, in Comparative Example 1, the variation in rigidity (± 2σ) was 1.2 k.
g / μm or more, the rigidity itself is 5.96k at the center
g / μm. Also in Comparative Example 2, the variation in rigidity (± 2σ) was 0.5 kg / μm or more, and the rigidity value itself was as low as 6.26 kg / μm at the center.

On the other hand, in the partial rigidity table of the air slide of the present invention, as shown in Table 3, the variation in rigidity (± 2σ) is as small as 0.4 kg / μm or less, and the rigidity value is 9.66 kg / cm at the center. μm.

[0021]

[Table 1] Comparative Example 1

[0022]

[Table 2] Comparative Example 2

[0023]

[Table 3] Example of the present invention

Next, the manufacturing processes of the present invention and a comparative example were compared. First, as shown below, the manufacturing process of the comparative example requires many steps, and it can be seen that the number of steps (time) is long. Especially 8. And wrapping of 9. The weight of the pocket grooving process is large.
The man-hour is a value obtained by dividing the total processing cost by the time cost per person.

Comparative Example 1. Mixing of ceramic raw materials 0.48 hours 2. Large frame molding of members (rubber press, cast molding, etc.) 1.21 3. Drying 0.21 4. Raw cutting (cutting unnecessary parts in advance) (drilling and grooving) 1.88 5. Firing 1.55 6. Adhesion and hardening of drawn hole tip and nut bush 2.22 7. Grinding (forming to an accuracy of about ± 5 μm) 1.32 8. Lap processing (hand processing to an accuracy of ± 1 μm or less) 3.24 9. Pocket grooving (diamond milling) 4.22 10. Slide assembly 1.56 11. Measurement, lap adjustment 2.45 total 30.34

Next, the processing steps and man-hours of the present invention are as follows. One man-hour compared to the above example of integrated processing
It can be seen that this was greatly improved to / 3 or less.

The present invention 1. Mixing of ceramic raw materials 0.48 hours 2. Large frame molding of members (cast molding) 0.44 3. Drying 0.18 4. Press forming of squeeze nozzle 0.08 5. Firing 1.65 6. Adhesion and hardening of nut bush 1.68 7. Grinding (forming to an accuracy of about ± 5 μm) 0.44 8. Grinding, lapping, and mounting of throttle nozzle 0.34 9. Slide assembly 1.56 10. Measurement, lap adjustment 2.45 total 9.30

As described above, according to the present invention, a throttle hole and a surface throttle communicating therewith are provided on a base plate having an air passage hole, which constitutes a sliding body of a hydrostatic bearing device, A plurality of pocket members made of ceramics in which the apertures and / or surface apertures are formed by press molding are joined so that the apertures of the pocket members communicate with the air communication holes, respectively, and are connected to the air communication holes. Since the supplied fluid is ejected from the throttle hole toward the guide shaft, it is possible to easily and accurately process the throttle hole and the surface throttle having a complicated structure, and increase the number of pockets. Can be. As a result, the rigidity, which is the basic characteristic of the hydrostatic bearing device, is 1.5 times or more, and the partial rigidity is stabilized, so that it can be used for applications with a large load, and is used for ultra-precision measuring and processing machines You. Further, since the manufacturing process is shortened, many effects can be achieved, such as reduction in cost and stable supply of highly accurate products.

[Brief description of the drawings]

FIG. 1 is a perspective view of only a base plate constituting an air slide which is an embodiment of the hydrostatic bearing device of the present invention.

FIG. 2 is a sectional view taken along line XX in FIG.

3A and 3B are cross-sectional views showing another embodiment of the present invention corresponding to FIG.

FIG. 4 is a schematic view illustrating a thrust bearing of an air bearing according to another embodiment of the present invention.

FIG. 5 is a schematic view showing a radial bearing of an air bearing according to another embodiment of the present invention.

FIG. 6 is a perspective view showing an air slide as an example of a hydrostatic bearing device.

FIG. 7 is a perspective view of only a base plate constituting a conventional air slide.

FIG. 8 is a sectional view taken along line YY in FIG. 7;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Sliding body 2 Guide shaft 10 Base plate 11 Pocket member 12 Restriction hole 13 Surface restriction 15 Base plate main body 16 Air conduction hole

Claims (1)

(57) [Scope of request for utility model registration] An aperture and a surface aperture communicating with the aperture are provided on a base plate having an air passage hole.
Alternatively, a plurality of pocket members made of ceramics whose surface drawing is formed by press molding are joined so that the drawing holes of each pocket member communicate with the air conducting holes, respectively, and the fluid supplied to the air conducting holes is formed. A hydrostatic bearing device which is ejected from the throttle hole toward the guide shaft.