JPS6348809Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field This invention relates to a static pressure slide that uses a static air bearing to move a moving table in a non-contact manner with respect to a guide portion.

PRIOR ART As shown in Figures 7 and 8, a hydrostatic slide using a hydrostatic air bearing is configured such that a moving table 2 is provided on a table guide 1 so as to embrace it, and a minute bearing gap 9 is formed between the table guide 1 and the moving table 2, and compressed air is introduced into this bearing gap to create an appropriate pressure distribution, and a load is applied to this to move the moving table 2. In such a hydrostatic slide, the usual method of introducing compressed air into the bearing gap is to supply compressed air to the moving table 2 via an air hose 3, and have the compressed air jet out from the moving table 2 into the bearing gap.

Problems to be Solved by the Invention Hydrostatic slides as described above are often used in fields that require highly accurate straightness and positioning, and have recently also been used in fields that require high submicron precision. . However, when the air hose 3 is connected to the movable table 2, the linearity of the movable table 2 is impaired due to resistance when the air hose 2 is bent as the movable table 2 moves, and it is not possible to move the movable table 2 in a straight line with high accuracy. There was a problem that the accuracy and positioning could not be obtained.

That is, the air hose 3 connected to the moving table 2 is a pipe with a large diameter in order to circulate a large amount of compressed air, and even if it is made of a flexible material, the air hose 3 does not allow the flow of compressed air. Since the air hose 3 sometimes tends to become rod-shaped, when the air hose 3 bends as the movable table 2 moves, the resistance is large and the ability to move straight is sometimes impaired. Further, if the diameter of the air hose 3 is made thinner in order to reduce the resistance, problems such as insufficient flow rate of compressed air and deterioration of bearing performance occur.

Furthermore, since the air hose 3 is long to allow movement of the moving table 2,
This air hose 3 must be arranged so that it does not interfere with the moving table 2 or table guide 1.
A large installation space was required.

Therefore, in order to solve the above problems,
An air hose 3 may be provided on the table guide 1 to supply compressed air from the table guide 1 side to the bearing clearance, but there are many problems in doing so. That is, the static pressure slide must supply compressed air over the entire surface between the movable table 2 and the table guide 1, no matter what position the movable table 2 moves to. However,
In order to supply compressed air to the entire movement range of the movable table 2, as shown in FIG. 5, 5... are provided on almost the entire surface of the table guide 1, the movable table 2
Since compressed air leaks and is released in large quantities from the air supply holes 5, 5, etc., which are not opposed to the air supply holes 5, 5, etc., the consumption of compressed air increases, increasing running costs, and the internal pressure of the air supply passage 4 decreases, which increases the load on the bearings. There was a problem that the capacity also decreased. Therefore, this method cannot be applied if the movement stroke of the moving table 2 becomes long.

In addition, when the moving stroke of the moving table 2 is short, as shown in FIG. Although there is no air leakage and the load capacity is high, the moving table 2
, the pressure distribution of the compressed air within the bearing clearance 9 becomes uneven, causing the movable table 2 to tilt, and in extreme cases, the movable table 2 may overturn the table guide 1
I had a problem where I could not move when I came in contact with something.

In addition, in order to uniformly supply compressed air to the entire bearing clearance 9, an air supply hole 7 is formed in the center of the table guide 1, as shown in FIG.
A pocket 8 is formed on the inner surface of the table guide 1 in the direction of movement in correspondence with the air supply hole 7, and compressed air is jetted from the pocket 8 into the bearing clearance 9, thereby creating a uniform pressure distribution between the table guide 1 and the moving table 2. In order to create a pocket 8, a large-capacity pocket 8 is required, and if the depth is increased, self-excited vibrations occur due to the compressibility of air, which impairs straight-line performance. Therefore, if submicron positioning is required, it is not possible to connect an air hose to the table guide 1 side.

Means for Solving the Problems This invention is a static pressure slide in which a movable table moves within a short range along a table guide. A plurality of air supply holes are formed that branch from the air passage in a direction perpendicular to each other and open on the surface of the table guide, and are arranged on the inner surface of the movable table to face the air supply holes so as to be self-excited with respect to the flow rate of compressed air supplied from the air supply holes. Form a pocket that has a volume that does not cause vibration, is slightly wider than the diameter of the air supply hole, and has a length that is equal to or slightly longer than the moving stroke of the moving table, and a A narrow and deep auxiliary groove is formed, and many narrow bearing grooves are branched from the auxiliary groove to supply compressed air from the air supply passage of the table guide to the pocket of the movable table via the air supply hole. However, the pressure distribution inside the pocket is made uniform and self-excited vibration of the moving table is prevented.

Embodiment FIGS. 1 and 2 are drawings showing an embodiment of the present invention. In the figures, 10 is a table guide formed in a portal shape, and the horizontal guide portion 10a has a central portion along the longitudinal direction. An air supply passage 11 is formed over substantially the entire length from one end, and a plurality of small-diameter air supply holes 12, 12 are formed perpendicularly to the air supply passage 11 at two locations in the middle of the air supply passage 11, for example. Four pieces are formed on the top and bottom surfaces, and two pieces are formed on the sides. These air supply holes 12, 12... have an orifice 13 near the opening,
13... are formed.

Reference numeral 14 denotes a movable table that is slidably held by the guide portion 10a of the table guide 10, and is formed into a rectangular tube shape, with a minute bearing clearance 15 between the inner surface of the movable table 14 and the outer surface of the table guide 10. has been formed. The upper surface of this moving table 14 is formed into a horizontal surface so that various devices can be attached thereto. Further, on the inner surface of the moving table 14, for example, the upper and lower surfaces, as shown in FIGS. 3 and 4,
An exhaust groove 16 is formed in a square shape to form lands 17, 17 divided into four parts, and each land 17, 17 is divided into four parts.
The air supply holes 12, 12 of the table guide 10 are...
Pocket 1 along the direction of movement in the center corresponding to
8, 18..., and these pockets 18, 18...
Narrow and deep auxiliary grooves 19, 19... are formed in the inner part of the auxiliary grooves 19, 19... with approximately the same length, and further auxiliary grooves 19, 19...
Bearing grooves 20, 20, . . . are formed branching from the land 17 and extending in a grid pattern over the entire area of the land 17.

The length of the pocket 18 is equal to or slightly longer than the movement stroke of the moving table 14, and the length is slightly larger than the diameter of the air supply hole 12 (0.5 to 1 mm).
It has a wide groove width and is formed at a depth (10 to 30 μm) that allows the compressed air supplied to the inside to have a capacity that does not cause self-excited vibrations under the influence of external disturbances. In addition, the auxiliary groove 19 has a depth and groove width that can compensate for the lack of capacity of the pocket 18 and provide a uniform pressure distribution within the pocket 18, for example, a depth of 30 to 100 μm and a groove width of 0.5 to 1.0 mm. Selection has been formed.
Further, the bearing groove 20 is formed to be slightly narrower and shallower than the auxiliary groove 19.

The pockets 18, auxiliary grooves 19, and bearing grooves 20 are formed not only on the upper and lower inner surfaces of the movable table 14, but also on both left and right inner surfaces, and constitute a static air bearing over the entire circumference of the movable table 14. It is designed to do so.

An air hose 21 is connected to the air supply passage 11 of the table guide 10, and supplies compressed air generated by a compressor (not shown) to the air supply passage 11.

In the static pressure slide having the above structure, when compressed air generated by the compressor is supplied to the air supply passage 11 of the table guide 10 through the air hose 21, the compressed air is transferred from the air supply passage 11 to each air supply hole 12, 12, . . .
It passes through the orifices 13, 13... and squirts out, enters the opposing pockets 18, 18, where it enters the pockets 18, 18... and the auxiliary grooves 19, 19.
... and further flows into the bearing grooves 20, 20..., and flows into the pockets 18, 18... and the bearing grooves 20, 20.
A uniform pressure is introduced into the bearing clearance 15 from ... to create a uniform pressure distribution, and as a result, the moving table 1
Load 4. In this state, a suitable driving means (not shown) such as a ball screw or a linear motor is activated.
The movable table 14 is moved back and forth, and various types of processing are performed using the devices on the movable table 14.

5 and 6 are drawings showing other embodiments,
This has two auxiliary grooves 22 at the back of the pocket 18,
22.

Effects of the invention This invention forms an auxiliary groove with a narrow groove width and a deep depth at the back of the pocket formed on the movable table, so that even if the shape of the pocket is made smaller, no pressure gradient will occur inside the pocket. The fluid can flow sufficiently within the pocket, and the pressure distribution can be made uniform and the load capacity can be increased without causing self-excited vibration. Generally, if the capacity of the pocket formed in the movable table is increased, the pressure distribution can be made uniform, but self-excited vibration occurs.

That is, the flow rate Q of the compressed air supplied to the pocket flowing in the longitudinal direction is expressed by the following equation.

Q=1/μ・Bh ³ /12・2p/2x However, μ: Fluid viscosity coefficient, B: Groove width, h: Depth, x: Longitudinal dimension, p: Pressure When the above equation is transformed, 2P/ 2x=12・μ・Q・1/B・h ³ , and as can be seen from this formula, if the flow rate of compressed air supplied from the air supply hole to the pocket is constant, the pressure change inside the pocket will be equal to the groove width B. It is inversely proportional to the first power of h and the cube of the depth h. Therefore, in order to reduce the pressure change in the longitudinal direction, it is preferable to narrow the groove width of the pocket and increase the depth.

Therefore, in the device according to the present invention, even if the groove width of the pocket is slightly wider than the diameter of the air supply hole, the depth of the groove is made shallow, and the auxiliary groove, which is narrow in groove width and deep, is used to fill the inside of the pocket. By making it easier for fluid to flow, it is possible to suppress self-excited vibrations, eliminate pressure gradients within the pocket, create a uniform pressure distribution in the bearing clearance, and construct a static pressure slide with a high load capacity. Furthermore, since an air hose that sends compressed air can be provided to the table guide, there is less resistance when moving the moving table, and highly accurate positioning can be achieved. If applied to a positioning device or the like, highly accurate positioning can be performed.

[Brief explanation of drawings]

Fig. 1 is a vertical cross-sectional view of the static pressure slide according to the present invention, Fig. 2 is a perspective view of the static pressure slide of the invention, Fig. 3 is a plan view of the main part showing the inner shape of the moving table, and Fig. 4 is FIG. 5 is an enlarged cross-sectional view showing the shape of the pocket and auxiliary groove of the movable table, FIG. 5 is a plan view of the main part of the movable table showing another embodiment, and FIG. 6 is an enlarged longitudinal cross-sectional view showing the shape of the pocket of another embodiment. 7 is a perspective view of a conventional hydrostatic slide, FIG. 8 is a drawing showing the principle of the hydrostatic slide, and FIGS. 9 to 11 are sectional views of main parts showing disadvantages of the conventional slide. 10...Table guide, 11...Air supply passage,
12... Air supply hole, 13... Orifice, 14...
Moving table, 15...Bearing clearance, 16...Exhaust groove, 18...Pocket, 19...Auxiliary groove, 20
...Bearing groove, 21...Air hose.

Claims (1)

[Scope of utility model registration request] The movable table is held by the table guide, a minute bearing gap is formed between the movable table and the table guide, compressed air is introduced into this bearing gap to create an appropriate pressure distribution, and a load is applied to this. In a static pressure slide that moves a moving table within a short range, an air supply passage is formed in the center of the table guide in the longitudinal direction, and an air supply hole is formed that branches from the air supply passage and opens on the surface of the table guide. forming a pocket on the inner surface of the movable table, facing the air supply hole, having a groove width slightly wider than the diameter of the air supply hole and a length equal to or slightly longer than the movement stroke of the movable table; A static pressure slide characterized in that an auxiliary groove having a narrow groove width and a deep depth is formed in the inner part of the pocket in the movement direction, and further a bearing groove is formed branching from the auxiliary groove.