CN115127810B

CN115127810B - Loading mechanism of non-contact plane air bearing test bench

Info

Publication number: CN115127810B
Application number: CN202210689658.2A
Authority: CN
Inventors: 李岩; 宁延强; 张德胜; 孙云洋
Original assignee: Jiangsu University; Zhenjiang Fluid Engineering Equipment Technology Research Institute of Jiangsu University
Current assignee: Jiangsu University; Zhenjiang Fluid Engineering Equipment Technology Research Institute of Jiangsu University
Priority date: 2022-06-16
Filing date: 2022-06-16
Publication date: 2025-09-05
Anticipated expiration: 2042-06-16
Also published as: CN115127810A

Abstract

The invention discloses a non-contact type plane air bearing test bed loading mechanism which mainly comprises an upper pressure head and a positive pressure loading module, wherein the lower part of the positive pressure loading module is arranged on the upper end surface of a tested plane air bearing, and the upper pressure head and the positive pressure loading module are connected through a ball bearing. The pressure head comprises a loading bolt, a hand wheel and a fixed frame, wherein the hand wheel and the fixed frame are arranged on the loading bolt, the positive pressure loading module comprises a positive pressure air inlet, a positive pressure cavity and an elastic foil, high-pressure air is introduced into the positive pressure loading module through the positive pressure air inlet to load the tested plane air bearing, an air film is formed between the positive pressure loading module and the upper surface of the plane air bearing during testing, loading force is applied to the tested plane air bearing through the air film, a certain gap is formed between two opposite movable surfaces, and the air film is loaded in a non-direct contact mode. The test bed loading mechanism of the invention has the advantages of no contact with the air bearing of the plane to be tested, dynamic detection and convenient operation when loading.

Description

Non-contact type plane air bearing test bed loading mechanism

Technical Field

The invention relates to the field of performance test of plane air bearing, in particular to a loading mechanism of a non-contact plane air bearing test bed.

Background

The ultra-precise air floatation moving platform adopts a plane air floatation bearing to eliminate friction force and mechanical creeping phenomenon between moving friction pairs, realizes ultra-precise positioning of objects such as parts, samples and the like, and is widely applied to the fields of photoetching technology, numerical control processing, biotechnology, microscopic measurement and the like. The plane air bearing introduces high-pressure gas into a relatively moving object gap to form a gas film, and provides bearing force through the pressure of the gas film, so that direct contact friction between kinematic pairs is eliminated, and the functions of supporting and lubricating are realized.

The performance test of the plane air bearing has higher precision requirement, and generally has the advantages of high loading precision, no additional moment generation, no influence on the motion of the air bearing and the like. The traditional loading mechanism often has certain rigidity, and when the thickness of the air film of the measured bearing changes, the loading surface generates tiny displacement along the loading direction, so that the loading force changes greatly. In addition, conventional loading mechanisms also have difficulty in providing a controllable, high precision loading force with typical machining precision.

Disclosure of Invention

In order to solve the problems that loading and unbalance loading of a plane air bearing cannot be realized in the prior art, the invention provides a non-contact type loading mechanism of a plane air bearing test bed, which can detect the bearing capacity and the air film thickness of the plane air bearing under different air supply pressures and different loads and has important significance for optimizing design, theoretical analysis, performance improvement and the like of structural parameters of the plane air bearing.

The invention solves the loading problem by adopting the technical scheme that the non-contact type plane air bearing test bed loading mechanism is characterized in that the plane air bearing test bed mainly comprises a marble table top 10, a loading mechanism, an equipment table frame, a universal meter, a pressure regulating valve and an air compressor. The test bed loading mechanism mainly comprises an upper pressure head and a positive pressure loading module, wherein the lower part of the positive pressure loading module is arranged on the upper end face of an air bearing of a plane to be tested, and the upper pressure head and the positive pressure loading module are connected through a ball bearing. The pressure head comprises a loading bolt, a loading hand wheel arranged on the loading bolt and a fixed frame, and the positive pressure loading module comprises a positive pressure air inlet, a positive pressure cavity and an elastic foil. The measured plane air bearing is filled with high-pressure gas through the high-pressure gas supply port, and the positive pressure loading module is filled with high-pressure gas through the positive pressure gas inlet, so that the measured plane air bearing is loaded.

The positive pressure loading module is controlled to move upwards or downwards by rotating the loading hand wheel, and the loading bolt adopts fine threads, so that the accuracy of controlling the movement amount of the positive pressure loading module is higher.

During testing, an air film is generated between the positive pressure loading module and the air bearing on the measured plane, loading force is applied to the air bearing on the measured plane through the air film, a certain gap is formed between two opposite movable surfaces, and the air bearing is not in direct contact.

The loading force is applied to the measured plane air bearing through the air film, so that the applied force is uniform, and the eccentric moment and the tilting moment are not generated on the measured plane air bearing.

The loading mechanism is free from tiny errors in the processing and assembling processes of all parts, loading force is applied to the tested plane air bearing through the air film and is applied in a non-direct contact mode, the size of the loading force is determined by air supply pressure, and the loading accuracy is not influenced by the errors of the processing and the assembling of the parts during testing.

4 Elastic foils are arranged below the positive pressure cavity, and the included angle between the elastic foils and the positive pressure cavity is 30 degrees by adopting laser spot welding. In the loading process, the clearance between the movable surface of the positive pressure cavity and the air bearing of the measured plane is 0.1-0.5 mm, non-contact sealing is realized through the elastic foil, the elastic foil generates elastic deformation under the action of pressure, and the clearance between the elastic foil and the upper surface of the air bearing of the measured plane is in a micron level.

A chamber for storing high-pressure gas is formed between the lower surface of the positive pressure cavity and the measured plane air bearing, and loading force is provided for the measured plane air bearing through gas pressure.

Compared with the prior art, the invention has the following advantages:

1. The positive pressure loading module and the measured plane air bearing are loaded through the air film, a certain gap is formed, the air film is not in direct contact, the measured plane air bearing is not subjected to any additional force during testing, the loading force is more uniform, the loading precision is higher, and the problems of small loading range, large error and the like in the existing loading mechanism are solved.

2. In the invention, 4 elastic foils are arranged below the positive pressure cavity, the included angle between the elastic foils and the positive pressure cavity is 30 degrees by adopting laser spot welding, and the elastic foils deform under the action of pressure during testing, so that a micron-sized gap is formed between the elastic foils and the upper surface of the tested plane air bearing, and the loading precision is higher.

3. Because the thickness of the air film at the elastic foil is in the micron level, the flow loss of the high-pressure air from the air source into the positive pressure cavity is far smaller than the flow loss near the elastic foil, and the pressure in the positive pressure cavity is approximately equal to the air supply pressure. Thus, the loading force is proportional to the air supply pressure. When the measured plane air bearing is vibrated in the micron order along the loading direction, the loading mechanism can keep the loading force constant.

4. The loading mechanism is free from tiny errors in the processing and assembling processes, and the thickness of the air film of the air bearing on the measured plane is in the micron level, so that even small manufacturing errors can greatly influence the thickness of the air film. According to the invention, the loading bolt is connected with the loading module through the ball bearing, so that the angle between the positive pressure loading module and the measured plane air bearing can be adjusted, the measured plane air bearing and the loading module are kept relatively parallel during testing, and the applied loading force can not generate eccentric and inclined moment on the measured plane air bearing.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments, as illustrated in the accompanying drawings.

Drawings

In order to more clearly illustrate the embodiments of the invention or the technical solutions in the prior art, the drawings that are required in the embodiments or the description of the prior art will be briefly described, it being obvious that the drawings in the following description are only some embodiments of the invention, and that other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.

FIG. 1 is a side view of a loading mechanism according to an embodiment of the present invention;

FIG. 2is a schematic view of a loading mechanism according to an embodiment of the present invention;

FIG. 3 (a) is a front view of a positive pressure loading module according to an embodiment of the present invention;

FIG. 3 (b) is a cross-sectional view taken at A-A in FIG. 3 (a);

FIG. 3 (c) is a top view of a positive pressure loading module according to an embodiment of the present invention;

FIG. 3 (d) is a bottom view of the positive pressure loading module according to the embodiment of the present invention;

FIG. 4 is a schematic diagram of a functional connection according to an embodiment of the present invention;

FIG. 5 is a graph showing the linear relationship between the air supply pressure and the load force in an embodiment of the present invention.

The reference numerals of the drawings comprise 1, a loading hand wheel, 2, a loading bolt, 3, a fixed frame, 4, a ball bearing, 5, a positive pressure cavity, 6, a positive pressure air inlet, 7, an elastic foil, 8, a measured plane air bearing, 9, a high pressure air supply port and 10, a marble table top.

Detailed Description

The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.

Referring to fig. 1-3 (d), a loading mechanism of a non-contact type plane air bearing test bed mainly comprises an upper pressure head and a positive pressure loading module, wherein the lower part of the positive pressure loading module is arranged on the upper end face of a tested plane air bearing 8, and the upper pressure head and the positive pressure loading module are connected through a ball bearing 4. The pressure head comprises a loading bolt 2, a loading hand wheel 1 arranged on the loading bolt 2 and a fixed frame 3, and the positive pressure loading module comprises a positive pressure air inlet 6, a positive pressure cavity 5 and an elastic foil 7. The measured plane air bearing 8 is filled with high-pressure gas through the high-pressure gas supply port 9, and the positive pressure loading module is filled with high-pressure gas through the positive pressure gas inlet 6 to load the measured plane air bearing 8.

The positive pressure loading module is controlled to move upwards or downwards by rotating the loading hand wheel 1, and the loading bolt 2 adopts fine threads, so that the accuracy of controlling the movement amount of the positive pressure loading module is higher.

During testing, an air film is generated between the positive pressure loading module and the measured plane air bearing 8, loading force is applied to the measured plane air bearing 8 through the air film, a certain gap is formed between two opposite movable surfaces, and the two movable surfaces are not in direct contact.

The loading force is applied to the measured plane air bearing 8 through the air film, so that the applied force is uniform, and no eccentric and tilting moment is generated on the measured plane air bearing 8.

The loading mechanism is free from tiny errors in the processing and assembling processes of all parts, loading force is applied to the tested plane air bearing 8 through an air film and is applied in a non-direct contact mode, the size of the loading force is determined by air supply pressure, and the loading accuracy is not affected by the errors of the processing and the assembling of the parts during testing.

4 Elastic foils 7 are arranged below the positive pressure cavity 5, and the included angle between the elastic foils and the positive pressure cavity 5 is 30 degrees by adopting laser spot welding. In the loading process, the clearance between the movable surface of the positive pressure cavity 5 and the air bearing 8 on the measured plane is 0.1-0.5 mm, non-contact sealing is realized through the elastic foil 7, the elastic foil 7 generates elastic deformation under the action of pressure, and the clearance between the elastic foil 7 and the upper surface of the air bearing 8 on the measured plane is in the micron level.

A chamber for storing high-pressure gas is formed between the lower surface of the positive pressure cavity 5 and the measured plane air bearing 8, and loading force is provided for the measured plane air bearing 8 through gas pressure.

During testing, pneumatic quick connectors are arranged at the positive pressure air inlet 6 of the positive pressure cavity 5 and the high pressure air supply port 9 of the tested plane air bearing 8, and the pneumatic quick connectors are respectively connected with an air compressor by using a pneumatic pipe and a pressure regulating valve, as shown in fig. 4. After connecting the pipelines, the following operation steps are carried out:

1. starting a second pressure regulating valve to enable the tested plane air bearing 8 to start working;

2. The loading hand wheel 1 on the loading bolt 2 is used for controlling the movement of the loading bolt 2, the loading hand wheel 1 is rotated to enable the loading bolt 2 to move downwards until the elastic foil 7 contacts with the upper wall surface of the air bearing 8 of the measured plane, and the elastic foil 7 deforms;

3. the first pressure regulating valve is opened, the pressure in the inner cavity of the positive pressure cavity 5 is increased, the elastic foil 7 is further deformed under the action of the pressure, and a micron-sized gap is formed between the elastic foil 7 and the upper surface of the air bearing 8 of the measured plane.

Since the thickness of the air film at the elastic foil 7 is in the order of micrometers, the flow loss of the high-pressure air from the air source to the positive pressure cavity 5 is much smaller than that near the elastic foil 7, and the pressure in the positive pressure cavity 5 is approximately equal to the air supply pressure. Thus, the loading force is proportional to the air supply pressure. When the measured plane air bearing 8 has micron-sized vibration along the loading direction, the loading mechanism can keep the loading force constant.

According to the test requirements, the first pressure regulating valve is used for regulating the air supply pressure in the positive pressure cavity 5, namely regulating the loading force, and the second pressure regulating valve is used for regulating the working pressure of the air bearing 8 on the measured plane.

Taking the experimental parameters as an example, the working pressure range of the adopted air compressor is 0-0.8MPa, the size of the positive pressure cavity 5 is 0.2 multiplied by 0.2m, and the size of the internal cavity of the positive pressure cavity 5 is 0.17 multiplied by 0.17m. In this condition, the linear relationship between the air supply pressure of the positive pressure loading module and the data of the loading force is shown in fig. 5.

While the principles and embodiments of the present invention have been described in detail in the foregoing application of the principles and embodiments of the present invention, the above examples are provided for the purpose of aiding in the understanding of the principles and concepts of the present invention and may be varied in many ways by those of ordinary skill in the art in light of the teachings of the present invention, and the above descriptions should not be construed as limiting the invention.

Claims

1. A non-contact plane air bearing test bench loading mechanism, characterized by comprising:

The test bench loading mechanism mainly consists of an upper pressure head and a lower positive pressure loading module mounted on the upper end surface of the measured plane air bearing (8), the two being connected by a ball bearing (4); the pressure head includes a loading bolt (2), a loading handwheel (1), and a fixed frame (3);

The positive pressure loading module comprises a positive pressure air inlet (6), a positive pressure cavity (5), and an elastic foil (7);

The lower surface of the positive pressure cavity (5) has a cavity with a depth of millimeters;

Four pieces of the elastic foil (7) are installed around the cavity on the lower surface of the positive pressure cavity (5), and are connected to the positive pressure cavity (5) by laser spot welding at an angle of 30 degrees;

After high-pressure gas is introduced through the positive-pressure air inlet (6), the elastic foil (7) is deformed under the action of the pressure, so that a micrometer-level gap is formed between the elastic foil (7) and the upper surface of the measured plane air bearing (8);

The positive pressure loading module introduces high-pressure gas through the positive pressure air inlet (6) to load the plane air bearing (8) to be measured.

2. A non-contact planar air bearing test bench loading mechanism as described in claim 1, characterized in that: during testing, an air film is formed between the positive pressure loading module and the upper surface of the planar air bearing (8) to be tested, and a loading force is applied to the planar air bearing (8) to be tested through the air film, and there is a certain gap between the two relative active surfaces.

3. A non-contact plane air bearing test bench loading mechanism as claimed in claim 1, characterized in that after ventilation, the parallelism error between the positive pressure cavity (5) and the plane air bearing (8) to be tested is automatically compensated by the ball head bearing (4).

4. A non-contact planar air bearing test bench loading mechanism as described in claim 1, characterized in that: during testing, the positive pressure loading module is controlled to move upward or downward by rotating the loading handwheel (1), and the loading bolt adopts a fine thread, so that the movement of the positive pressure loading module is controlled with higher accuracy.