JPS5913119A - Static pressure fluid bearing - Google Patents

Abstract

PURPOSE:To heighten the straightness of the motion of a slider movably supported around a rectangular shaft, by changing the cross-sectional area of each air pocket of the sliding surface of the slider in the direction of its sliding. CONSTITUTION:A restrained-type slide unit comprises a guide 1 shaped as a rectangular shaft and provided with exhaust grooves 3 on the longitudinal corners, and a slider 2 which extends around the guide 1 and slides while being guided by the surface of the guide. An air supply passage 11 is provided in the guide 1 so that the air supply ports 12a, 12b of the downstream end of the passage are opened in the surface of the guide. The sliding surface 4 of the slider 2 is provided with deep grooves (air pockets) 13a, 13b parallel with the direction of the sliding. The width and depth of the air pocket 13a, which receives load through the slider 2, are gradually decreased toward both the ends in the direction of the sliding. The width and depth of the other air pocket 13b, which does not receive the load, are gradually increased toward both the ends in the direction of the sliding.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is used in precision machine tools, precision measuring machines, etc.
The present invention relates to a hydrostatic fluid bearing that uses a fluid such as air for lubrication between two relatively moving surfaces and constitutes a restraint type slide device or the like.

Structure of the conventional example and its problems FIG.
) is a guide having a child shaft shape and having an exhaust # (1>) at the corner of the outer periphery, (2) surrounds the surface of the guide (1) and uses the surface of the guide (1) as a guide surface (2) It is a sliding slider. ■ is slider (2)
Indicates the sliding direction.

Hereinafter, a conventional restraint-type slide device based on the above structure will be explained with reference to FIGS. 2 to 4. Slider (2
) are provided with deep grooves (hereinafter referred to as air pockets) (5) in parallel to the sliding direction (G), and from this air pocket (5) a T-shaped shallow constriction hole is formed. A plurality of grooves (6) are provided in a direction perpendicular to the sliding direction (2). Further, an air supply path (8) is provided inside the guide (1), and gas supplied from the outside passes through the front distribution air path (8) and passes through the air supply holes (7) on each guide surface. This leads to an air pocket (5) of the slider (2) facing each guide surface. The gas supplied to the air pocket (5) is exhausted through the gap between the guide surface of the guide (1) and the sliding surface (4) of the slider (2) as shown by the arrow in FIG. be done.

In the above-mentioned conventional restraint type slide device, the slider (
When a load is applied to 2), the guide (1) bends.

The amount of deflection of this guide (1) changes depending on the position of the slider (2). In addition, in order to reduce the weight of the device, if the guide (1) is made thinner or hollow, or if aluminum alloy is used for the material, the guide (1) will be deflected by the load and the slider (2) will be The change in the amount of deflection depending on the position becomes so large that it cannot be ignored. This guide (
The deflection in 1) and the change in the amount of deflection do not directly affect the straightness of the restraint type slide device. Generally, the amount of displacement of the slider (2) in the load direction due to the deflection of the guide (1) and changes in the amount of deflection is greatest when the slider (2) is located at the center of the guide (1), and toward both ends. gradually decrease according to

Purpose of the Invention The present invention solves the above-mentioned conventional drawbacks, and aims to prevent deterioration in straightness due to deflection of the guide and changes in the amount of deflection in a restraint gap slide device, etc., which is a hydrostatic fluid bearing. .

Structure of the Invention In order to achieve the above object, the present invention includes a guide in the shape of a child shaft, and a slider that surrounds the surface of the guide and uses the guide surface as a guide surface.

a deep groove parallel to the sliding direction on the sliding surface of the slider;
At least one supply hole for supplying working fluid to the deep groove is provided on the guiding surface of the guide of a hydrostatic fluid bearing provided with a plurality of shallow restrictive grooves extending from the deep groove, and the supply hole and the deep The supply hole and the deep groove are configured such that the area of the supply flow path formed at the joint with the groove gradually decreases or increases toward both ends of the slider in the sliding direction.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. In the following description, the basic configuration of the restraint type slide device, which is a hydrostatic fluid bearing using gas as the working fluid, is the same as that in FIG. 1. Therefore, it will be explained in conjunction with FIG.

In FIGS. 5 to 7, (■) indicates an air supply path provided inside the guide (1), (12a) (12bM communicates with the air supply path (Ill), and is connected to the guide surface of the guide (1). An open air supply hole, (taa) (tab) A deep #I# (
(hereinafter referred to as air pocket), (14a) (14
b) The junction between the air supply ports (12g) (12b) and the air pockets (13a) (13b), indicated by diagonal lines in Figure 1.
Also, the arrow ■ indicates the sliding direction of the slider (2), the arrow (g) indicates the direction of load application, and the arrow indicates the relative direction of the air supply holes (12a) (12b) of the guide (1) as the slider moves. The air pocket (13
In the shape of a), the groove width and groove depth are similar to that of the slider (2).
) The sliding direction ■ is formed so that it gradually decreases toward both ends. That is, the joint portion (14a
) and the gap between the joint (14a) and the air pocket (13a) are reduced. In addition, as shown in Figures 5 and 7, the shape of the air pocket (13b) on the side corresponding to the guide (1) surface that receives the load and the opposite guide (1) surface is determined by its groove width and groove. The depth is formed so as to gradually increase toward both ends in the sliding direction of the slider (2). That is, the air supply flow path area formed by the joint (14b) toward both ends and the joint (14b) and the air pocket (13
b) The gap between the bottom surfaces is gradually increased.

The operation of the above configuration will be explained below.

The gas supplied from the outside is passed through the air supply path (11) of the guide (1).
) to the air pockets (13a) (13b) of the slider (2) through the joints (14a) (14b). Then, the pressure loss of the gas passing through the joint (X4a) on the side corresponding to the surface of the guide (1) that receives the load gradually increases toward both ends of the slider (2) in the sliding direction ω, and air pockets) (13a ) is adjusted using the slider (2).
) is largest when located in the center of guide (1),
It gradually decreases toward both ends of the guide (1).

On the other hand, the pressure loss of the gas passing through the joint (t4b) on the side corresponding to the guide (1) surface opposite to the guide (1) surface that receives the load is as follows: The pressure in the air pocket (13b) is lowest when the slider (2) is located in the center of the guide (1), and gradually increases toward both ends of the guide (1). . And clearly (7) the pressure in the air pocket obviously affects the pressure of the working fluid and its pressure distribution on the sliding surface (4) of the slider (2). Therefore, as mentioned above, the air pocket (13 m
) and the pressure in the guide (1) opposite to the guide (1) surface.
1) Air pockets on the side corresponding to the surface) (13b) By creating a difference in the pressure within each air pocket)
(13a) (13b) D A difference occurs in the average pressure of the working fluid on the sliding surface. This average pressure difference is a (kgfA1/
l) and the sliding surface area is bct-d), then %aX
A force of b (kgf) acts in the opposite direction of the load.

The value of a can be set to a magnitude on the order of a comma number kgfAII by design, and the value of a can be set to a magnitude on the order of a comma number kgfAII, and the value of
) can also be varied depending on the position. still,
Rigidity (not including the elasticity of the guide part of the slide device)
That is, if the ratio of the load to the change in the gap between the guide (1) and the slider (2) is c (kgf/μm), then
The displacement of the slider (2) due to the pressure difference is aXb/c
(μ-), the direction of this displacement is opposite to the direction of displacement of the slider (2) due to the change in the amount of deflection and deflection (8) of the guide (1). The displacement of the slider (2) due to the deflection of the guide (1) and the change in the amount of deflection is at most on the order of a few tenths of μ, and if a=01 (
1wf/1r1), ba o (cm), C=10
Cktzf/pg ), then the amount of displacement of the slider (2) due to the pressure difference is.

aXb/C(/7@)=:(LIX50/10=α5μ
It is bulky and has a sufficient value in terms of order, so that the straightness of the restraint type slide device can be improved.

8 and 9 show another embodiment of the present invention, in which an air pocket Qm is formed such that the groove width and the groove depth gradually decrease toward both ends in the sliding direction of the slider (2).
, the two air supply holes -(lη) are opposed to each other.If the two air supply holes (I・Qη) are in this way, the air pocket (1-) and each air supply hole Qfl(lη The area of the air supply flow path formed by the joint 1181 (11) can be gradually reduced toward both ends of the slider (2) in the sliding direction Q compared to the case where there is only one power supply hole. , air bubble) (the pressure inside lυ can also be varied efficiently. This also applies when the supply current path area is gradually increased toward both ends of the slider (2) in the sliding direction (g). Moreover, the number of air supply holes facing the - number of air pockets is not limited to two, and may be two or more.

Although the above embodiments have been described using gas as the working fluid, the present invention is applicable not only to gas but also to liquids such as oil and water.

Effects of the Invention As described above, according to the present invention, it is possible to prevent deterioration of straightness due to deflection of the guide and change in deflection of a constrained type slide device, etc., which is a hydrostatic fluid bearing, and to achieve higher precision. hydrostatic fluid bearings.

[Brief explanation of drawings]

Fig. 1 is a perspective view showing the basic structure of a restraint-type slide device that is a hydrostatic fluid bearing, Fig. 2 is a perspective view showing a part of a conventional slider, Fig. 3 is a perspective view of the same guide, and Fig. 4 is an explanatory diagram showing the flow of gas on a conventional sliding surface, FIG. 5 is a schematic diagram showing an embodiment of the present invention, FIG. 6 is a view taken from arrow A in FIG. 5, and FIG. 8 is a schematic view showing another embodiment, and FIG. 9 is a view taken along arrow C in FIG. 8. (1)...Guide% (2)...Slider, (3)
...Exhaust groove, (4)...Sliding surface, [+1) =...
Air supply path, (12a) (12b) 061 (lη... air supply hole, (13a) (13b) f16) - air pocket, (14a) (14b M81 (l!... joint, ■)
...The sliding direction of the slider, the target...the direction in which the load is applied, the moving direction of the air supply hole Agent Yoshihiro MorimotoFigure 1Figure 2Figure 3Figure 4Figure 5Figure 5 Figure 7 Figure 1 c Figure q

Claims (1)

[Claims] L has a guide in the shape of a child shaft, and a slider surrounding the guide surface and using the guide surface as a guide surface, and a deep groove parallel to the sliding direction on the sliding surface of the slider. , a hydrostatic fluid bearing having a plurality of shallow constriction grooves extending from the deep groove, wherein the guide surface of the guide is provided with at least one supply hole for supplying working fluid to the deep groove; The supply hole and the deep groove are configured such that the supply flow path area formed at the junction between the supply hole and the deep groove gradually decreases or increases toward both ends in the sliding direction of the slider. 2. The hydrostatic fluid bearing according to claim 1, wherein the depth of the deep groove gradually decreases or increases toward both ends of the slider in the sliding direction. (1) a The supply flow path area or the depth of the deep groove gradually decreases toward both ends in the sliding direction of the slider on the side corresponding to the guide surface that receives the load via the slider, and 3. The hydrostatic fluid bearing according to claim 1, wherein the guide surface (111) corresponding to the guide surface on the opposite side of the guide surface gradually increases toward both ends in the sliding direction of the slider.