CN102128206A - An aerostatic thrust bearing - Google Patents

Abstract

The invention relates to an air static pressure thrust bearing.A bearing body is provided with an air inlet, a ring groove, a plurality of throttling holes, a plurality of air cavities, an air storage cavity, a plurality of damping holes, a bearing working surface and an upper plane; the bearing comprises a bearing body, wherein annular grooves are arranged at the positions, vertically inwards, of the upper plane of the bearing body and at the position of the inner side end of an air inlet, a through hole is formed in one side wall of each annular groove, and the through holes are connected and communicated with the inner side end of the air inlet; the bearing body is positioned between the supported piece and the smooth plane, and the upper plane and the bearing working plane of the bearing body are respectively parallel to the inner plane and the smooth plane of the supported piece; a throttling hole, an air cavity and damping holes are respectively arranged in the bearing working face vertically towards the interior of the bearing body, two ports of the throttling hole are respectively connected and communicated with the annular groove and the air cavity, and an inflow port of each damping hole is positioned below the air storage cavity; the air cavity and the outflow port of the damping hole are positioned on the bearing working surface; the central position of the bearing body is provided with an air storage cavity which is communicated with the bearing working surface through a damping hole.

Description

An aerostatic thrust bearing

technical field

The invention relates to an aerostatic thrust bearing, which is mainly used for the design of moving parts in photolithography machines, three-coordinate measuring machines and other equipment, and belongs to the technical fields of ultra-precision motion and ultra-precision measurement.

Background technique

Aerostatic thrust bearings have a series of advantages such as no wear, low friction, no creeping at low speeds, and high motion precision, so they are widely used in the fields of ultra-precision motion and precision measurement, but at the same time, they also have low rigidity, low load-carrying capacity, and poor stability. shortcoming.

Increasing the air supply pressure, changing the shape of the air cavity, adding vacuum or electromagnetic preload can effectively improve the bearing capacity and stiffness of the air bearing, but the effect on the stability of the bearing is not obvious. This is because in the existing aerostatic thrust bearing structure, high-pressure gas enters the air cavity through the small hole restrictor, and then enters the bearing gap from the edge of the air cavity; the pressure in the air cavity gradually decreases along the bearing gap, and reaches the edge of the bearing. The pressure drop is the ambient pressure, and the system damping mainly comes from the viscous friction of the gas molecules at the orifice and the working gap of the bearing, and its damping value is very small. When the bearing is subjected to vibration or impact, small damping will lead to too long decay time and the system will be difficult to stabilize; in addition, the instability of the air supply will also cause micro-vibration of the bearing, which will affect the static and dynamic performance of the bearing.

With the development of ultra-precision motion and ultra-precision measurement technology, the system accuracy has reached the nanometer or even sub-nanometer level. At this time, the slight vibration of the system will have a serious impact on the positioning and measurement results; the air bearing system is widely used in ultra-precision motion, In the field of ultra-precision measurement, it is of great practical significance to improve its stability.

Contents of the invention

In order to overcome the disadvantages of low damping and poor stability of existing aerostatic thrust bearings, the purpose of the present invention is to improve the damping capacity of the aerostatic thrust bearings.

In order to achieve the above object, the present invention provides the technical solution adopted by the aerostatic thrust bearing to solve the technical problem as follows: it contains a supported part, a bearing body and a smooth plane; holes, multiple air chambers, air storage chambers, multiple damping holes and bearing working surface; the bearing body also has an upper plane; air inlets are arranged along the outer edge and radial direction of the bearing body; the plane of the bearing body is vertical to the inside There is a ring groove at the position of the inner side of the air inlet, and a through hole is formed on the side wall of the ring groove, and the through hole is closely connected and communicated with the inner side of the air inlet; the bearing body is located at the inner side of the air inlet Between the supporting part and the smooth plane, the upper plane and the bearing working surface of the bearing body are respectively parallel to the inner plane and the smooth plane of the supported part; a plurality of joints are respectively arranged at the position where the bearing working surface of the bearing body is perpendicular to the inside of the bearing body Orifice, multiple air cavities and multiple damping holes, the two ends of each throttling hole are respectively connected and communicated with the ring groove and each air cavity, and the inlet port of each damping hole is located under the air storage chamber; each The outlet port of each air cavity and each damping hole is located on the bearing working surface; the compressed air enters the ring groove from the air inlet, and then enters the air cavity through the throttle hole; there is an air storage cavity at the upper center of the bearing body , the air storage chamber communicates with the bearing working surface through the damping hole.

The beneficial effects of the present invention are: the bearing is provided with an air storage chamber with the largest possible volume and a plurality of damping holes. It enters the air storage chamber through the damping hole. At this time, the extrusion film effect of the gas in the air storage chamber acts as an air spring to absorb shock. Coupled with the friction and damping of multiple damping holes, the aerostatic thrust bearing is effectively improved. Excellent damping capacity enables the aerostatic thrust bearing to stabilize quickly, overcoming the disadvantages of traditional aerostatic thrust bearings that have a long attenuation time for vibration or impact and the system is difficult to stabilize. The damping hole is 0.1-0.3mm. If it is too large, it will lose the frictional damping of the gas. If it is too small, it will be difficult to process and easy to block the damping hole. Its processing can use the same processing technology as the throttle hole.

Description of drawings

Fig. 1 is a main sectional view of an aerostatic thrust bearing provided by the present invention.

Fig. 2 is a bottom view of the thrust bearing in Fig. 1 (a single row of holes is evenly distributed).

Fig. 3 is a bottom view of the thrust bearing in Fig. 1 (multiple rows of holes are uniformly distributed in the radial direction).

Figure 4 is a bottom view of the thrust bearing in Figure 1 (multiple rows of holes are radially staggered and evenly distributed)

Fig. 5 is a specific embodiment of the aerostatic thrust bearing in Fig. 1 .

Description of the components in the figure,

Detailed ways

The working principle, structure and specific implementation of the present invention will be further described below in conjunction with the accompanying drawings.

Fig. 1, Fig. 2 and Fig. 5 show the structure of the aerostatic thrust bearing provided by the present invention, the bearing includes a supported part 1, a bearing body 2 and a smooth plane 3. The bearing body 2 contains an air inlet 4, an annular groove 5, a plurality of throttle holes 6, a plurality of air chambers 7, an air storage chamber 8, a plurality of damping holes 9, and a bearing working surface 10; the bearing body 2 also has a Upper plane 12; air inlet 4 is arranged along the outer edge and radial direction of bearing body 2; ring groove 5 is arranged at the position vertically inward on the upper plane of bearing body 2 and at the inner side of air inlet 4, and in the ring groove There is a through hole 11 on the side wall of 5, and the inner end of the through hole 11 and the air inlet 4 is closely connected and communicated; the bearing body 2 is located between the supported part 1 and the smooth plane 3, and the bearing body 2 The upper plane 12 of the bearing body 2 and the bearing working surface 10 are respectively parallel to the inner plane of the supported part 1 and the smooth plane 3; a plurality of air cavities 7, A plurality of throttle holes 6 and a plurality of damping holes 9, the two ends of each throttle hole 6 are respectively connected and communicated with the ring groove 5 and each air chamber 7, and the inlet port of each damping hole 9 is located in the air storage chamber 8; the outflow ports of each air cavity 7 and damping hole 9 are located on the bearing working surface 10; compressed air enters the ring groove 5 from the air inlet 4, and then enters the air cavity 7 through the throttle hole 6; in the bearing An air storage chamber 8 is provided at the center of the upper plane 12 of the body 2 , and the air storage chamber 8 communicates with the bearing working surface 10 through the damping hole 9 . The annular groove 5 , the throttle hole 6 and the air cavity 7 are arranged symmetrically about the center. The plurality of throttle holes 6 are distributed symmetrically along the radial direction of the bearing body 2; the diameter of the damping holes 9 is 0.1mm-0.3mm; the supported part 1 and the bearing body 2 are sealed with an O-ring, and Fastened with screws. As shown in Figures 2 and 3, the plurality of damping holes 9 are evenly distributed radially on the bearing working surface 10; as shown in Figure 4, the damping holes 9 are arranged in single or multiple rows on the bearing working surface 10 Arranged and arranged side by side or staggered along the radial direction of the bearing body 2.

When the aerostatic thrust bearing of the present invention is fed with pressurized gas, the pressurized gas enters the annular groove 5 through the air inlet 4, enters the air chamber 7 through the orifice 6, and flows along the diameter of the aerostatic thrust bearing. The pressure difference between the working gas between the bearing working surface 10 and the smooth surface 3 and the surrounding atmosphere is used to support the aerostatic thrust bearing; a part of the gas enters the air storage chamber through the damping hole 9, when the air static pressure thrust When the bearing is impacted or vibrates due to an unstable air source, the gas in the working gap of the aerostatic thrust bearing enters the air storage chamber 8 through the damping hole 9, and the extrusion film effect of the gas in the air storage chamber 8 acts as an air barrier. The effect of the spring, coupled with the frictional damping of multiple damping holes 9, effectively improves the damping capacity of the aerostatic thrust bearing, that is, the air spring action of the air storage chamber 8 and the frictional damping of the damping holes 9 overcome the traditional The aerostatic thrust bearing has a long attenuation time for vibration or impact, and the system vibration is difficult to stabilize.

The above is only a specific implementation mode in the present invention, but the scope of protection of the present invention is not limited thereto. Anyone familiar with the technology can understand the conceivable transformation or replacement within the technical scope disclosed in the present invention. All should be covered within the scope of the present invention.

Claims (7)

1. An aerostatic thrust bearing, characterized in that: the aerostatic thrust bearing contains a supported member (1), a bearing body (2) and a smooth plane (3); on the bearing body (2) Contains air inlet (4), ring groove (5), multiple throttle holes (6), multiple air cavities (7), air storage cavity (8), multiple damping holes (9) and bearing working surface ( 10); the bearing body (2) also has an upper plane (12); the air inlet (4) is arranged along the outer edge and the radial direction of the bearing body (2); at the position where the plane of the bearing body (2) is vertical to the inside And the position at the inner side end of the air inlet (4) is provided with an annular groove (5), and a through hole (11) is arranged on the side wall of the annular groove (5), and the through hole (11) is connected with the air inlet ( 4) The inner side ends are tightly connected and connected; the bearing body (2) is located between the supported part (1) and the smooth plane (3), the upper plane (12) of the bearing body (2) and the bearing working surface (10 ) are parallel to the inner plane and the smooth plane (3) of the supported part (1) respectively; multiple throttling valves are respectively set at the position where the bearing working surface (10) of the bearing body (2) is perpendicular to the inside of the bearing body (2) hole (6), multiple air cavities (7) and multiple damping holes (9), the two ends of each throttling hole (6) are respectively connected and communicated with the ring groove (5) and each air cavity (7) , the inlet port of each damping hole (9) is located under the air storage chamber (8); the outlet port of each air chamber (7) and each damping hole (9) is located on the bearing working surface (10) ; Compressed air enters the ring groove (5) from the air inlet (4), and then enters the air cavity (7) through the orifice (6); an air storage cavity (8) is provided at the upper center of the bearing body (2) , the air storage cavity (8) communicates with the bearing working surface (10) through the damping hole (9). 2. The aerostatic thrust bearing according to claim 1, characterized in that, the annular groove (5), the throttle hole (6) and the air chamber (7) are arranged symmetrically about the center. 3. The aerostatic thrust bearing according to claim 1, characterized in that, a plurality of orifices (6) are symmetrically distributed along the radial direction of the bearing body (2). 4. The aerostatic thrust bearing according to claim 1, characterized in that a plurality of damping holes (9) are symmetrically distributed along the radial direction of the bearing body (2). 5. The aerostatic thrust bearing according to claim 1, characterized in that: the diameter of the damping hole (9) is 0.1mm-0.3mm. 6. The aerostatic thrust bearing according to claim 1, characterized in that an O-ring is used for sealing between the supported part (1) and the bearing body (2), and is fastened by screws. 7. The aerostatic thrust bearing according to claim 1, characterized in that: the damping holes (9) are arranged in single or multiple rows on the bearing working surface (10), and are arranged along the diameter of the bearing body (2). To parallel or staggered distribution.

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