Device and method for measuring and adjusting air film gap of air bearing

Abstract

The invention discloses an air film gap measuring and adjusting device and method for an air bearing, and relates to the technical field of air bearings, the device comprises an air bearing main body, the side surface of the air bearing main body is provided with a plurality of mounting holes, each mounting hole is communicated with one end of a corresponding vent hole, and the other end of the vent hole is provided with a plurality of air holes; the other end of the vent hole extends to the bottom surface of the air bearing main body; the air supply end of the installation hole is connected with an air supply pressure source through a first pipeline, a flow sensor is further arranged on the first pipeline, a pressure sensor is arranged between the flow sensor and the installation hole, and the pressure sensor is communicated with the first pipeline through a second pipeline. According to the invention, the air film gap of the air bearing can be determined and adjusted by using the fluid flow during the installation of the air floating unit and after the operation of the air floating platform system.

Description

Technical Field

[0001] The present invention relates to the technical field of air bearings, and particularly to a device and method for measuring and adjusting the air film gap of an air bearing. Background Art

[0002] Due to its characteristics such as almost zero friction, smooth movement, and homogenization effect of the fluid film, air bearings are particularly suitable for high-precision and high-speed applications. Air bearings are a special but strategically important product, and the development of air bearing technology is relied on by many industries globally, including microelectronics, semiconductors, medical, and optics.

[0003] The air film gap range for most air bearing applications is between a few micrometers and dozens of micrometers. The average gap is within 10 micrometers. Since it is difficult to measure such a small gap, it is very troublesome to correctly install and adjust the air film gap in a production environment or installation site.

[0004] Taking the air bearing pad (also known as air bearing foot, air bearing pad) unit widely used in many industries as an example, the air bearing pad is an application of an air bearing. It forms an air thin layer at the bottom of the air bearing pad to form a gap between the air bearing pad and the plane to form an approximately frictionless sliding condition. When installing with threads, the usual practice is to place the bearing in the component structure, apply a load at the center of the bearing with a threaded ball rod, and apply a locking torque according to experience. Then measure the comprehensive performance of the component, such as straightness and flatness. If the requirements are met, it is considered that the air film gap of the air bearing pad is within the normal range. If the performance requirements are not met, further adjust the threaded ball rod until the performance requirements are met. This trial-and-error adjustment method takes a long time and can only adjust the air film gap to a relatively appropriate range, but cannot accurately adjust it to the optimized design gap. There is also a method during the installation of the air bearing pad to measure the movement of the bearing by placing contact or non-contact sensors for measuring displacement. Then, repeatedly open and close the compressed air while recording the relative distance of the bearing translation. Although this method can estimate the air film gap, it also has problems and disadvantages. First, this is a measurement relatively far from the actual air film gap. Due to structural deformation, the measured displacement may not accurately reflect the actual thickness of the air film. Second, this method is very cumbersome, and due to space limitations, it is often impossible to place sensors for measuring displacement. In addition, during the operation of the equipment and the process of troubleshooting and detection, disassembling and verifying the gaps of all bearings is an expensive and time-consuming process.

[0005] Therefore, those skilled in the art have provided a method for measuring and adjusting the air film gap of an air bearing to solve the problems raised in the above background art. Summary of the Invention

[0006] The present invention provides a device and method for measuring and adjusting the air film gap of an air floating bearing, which uses fluid flow to determine and adjust the air film gap of the air floating bearing during the installation of the air floating unit and after the operation of the air floating platform system.

[0007] To achieve the above object, the present invention provides the following technical solutions:

[0008] A device for measuring and adjusting the air film gap of an air floating bearing according to the present invention includes an air floating bearing main body. A plurality of mounting holes are formed in the side surface of the air floating bearing main body. Each mounting hole is respectively communicated with one end of a corresponding ventilation hole, and the other end of the ventilation hole extends to the bottom surface of the air floating bearing main body;

[0009] The air supply end of the mounting hole is connected to an air supply pressure source through a first pipeline. A flow sensor is further provided on the first pipeline. A pressure sensor is provided between the flow sensor and the mounting hole. The pressure sensor is communicated with the first pipeline through a second pipeline.

[0010] Further, the ventilation hole includes a horizontal ventilation hole and a vertical ventilation hole. One end of the horizontal ventilation hole is communicated with the air outlet end of the mounting hole. The top end of the vertical ventilation hole is communicated with the horizontal ventilation hole, and the bottom end of the vertical ventilation hole extends to the bottom surface of the air floating bearing main body.

[0011] Further, a groove is formed on the top surface of the air floating bearing main body. The cross section of the groove is an inverted conical structure. A threaded ball rod is abutted in the groove. The ball head at the bottom end of the threaded ball rod abuts against the conical surface of the groove.

[0012] Further, the flow sensor is an analog sensor or a digital sensor.

[0013] Further, the pressure sensor is an analog sensor or a digital sensor.

[0014] A method for measuring and adjusting the air film gap of an air floating bearing according to an embodiment of the present invention includes:

[0015] S1. The air supply pressure source supplies air to the air floating bearing main body through the first pipeline, and the air supply pressure value is read through the pressure sensor;

[0016] S2. Rotate the threaded ball rod to apply a load to the air floating bearing main body;

[0017] S3. Read the air supply flow value through the flow sensor;

[0018] S4. The air film gap value can be obtained through the air supply flow value;

[0019] S5. Repeat steps S2-S4 until the required air film gap is reached.

[0020] In the above technical solution, a gas film gap measurement, adjustment device and method for an aerostatic bearing provided by the present invention have the following beneficial effects:

[0021] 1. In this application, by using a flow sensor and a pressure sensor, the flow value and the pressure value are measured, and the gas film gap value can be deduced. At the same time, by adjusting the flow value, the adjustment of the gas film gap can be realized, and the measurement and adjustment are more convenient.

[0022] 2. This application omits the contact or non-contact sensor for measuring displacement, and the whole measurement and adjustment process is more simple.

[0023] 3. This application is applicable to aerostatic bearings with various structural shapes. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can also be obtained based on these drawings.

[0025] Figure 1 It is the front view of a gas film gap measurement and adjustment device for an aerostatic bearing provided by an embodiment of the present invention;

[0026] Figure 2 It is the airflow schematic diagram between the aerostatic bearing main body and the parallel aerostatic support surface in the embodiment of the present invention;

[0027] Figure 3 It is the relationship curve graph of the flow rate and the gas film gap of a 100 mm circular aerostatic bearing in the embodiment of the present invention under a supply air pressure of 0.5 MPa.

[0028] Description of the reference numerals:

[0029] 10. Aerostatic bearing main body; 11. Mounting hole; 12. Ventilation hole; 13. Groove;

[0030] 121. Horizontal ventilation hole; 122. Vertical ventilation hole;

[0031] 20. First pipeline; 21. Second pipeline;

[0032] 30. Aerostatic support surface;

[0033] 40. Flow sensor;

[0034] 50. Pressure sensor;

[0035] 60. Threaded ball rod;

[0036] 70. Gas film. Detailed Implementation Modes

[0037] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with the accompanying drawings.

[0038] See Figure 1 as shown;

[0039] A device for measuring and adjusting the air film gap of an air floating bearing according to an embodiment of the present invention includes an air floating bearing main body 10. A plurality of mounting holes 11 are provided on the side surface of the air floating bearing main body 10. Each of the mounting holes 11 is respectively communicated with one end of a corresponding ventilation hole 12, and the other end of the ventilation hole 12 extends to the bottom surface of the air floating bearing main body 10.

[0040] The air supply end of the mounting hole 11 is connected to an air supply pressure source through a first pipeline 20. A flow sensor 40 is further provided on the first pipeline 20. A pressure sensor 50 is provided between the flow sensor 40 and the mounting hole 11. The pressure sensor 50 is communicated with the first pipeline 20 through a second pipeline 21.

[0041] During the measurement and adjustment process, the flow sensor 40 and the pressure sensor 50 can be fixed on the test bench.

[0042] The ventilation hole 12 includes a horizontal ventilation hole 121 and a vertical ventilation hole 122. One end of the horizontal ventilation hole 121 is communicated with the air outlet end of the mounting hole 11. The top end of the vertical ventilation hole 122 is communicated with the horizontal ventilation hole 121, and the bottom end of the vertical ventilation hole 122 extends to the bottom surface of the air floating bearing main body 10.

[0043] A groove 13 is provided on the top surface of the air floating bearing main body 10. The cross-section of the groove 13 is an inverted conical structure. A threaded ball rod 60 is abutted in the groove 13. The threaded ball rod 60 is threadedly connected to the upper end structure (not shown) on the workbench. The ball head at the bottom end of the threaded ball rod 60 abuts against the conical surface of the groove 13. Rotating the threaded ball rod 60 can apply force to the conical surface of the groove 13 through the ball head, thereby realizing the application of force to the entire air floating bearing main body 10.

[0044] The flow sensor 40 is an analog sensor or a digital sensor.

[0045] The pressure sensor 50 is an analog sensor or a digital sensor.

[0046] After the gas passes through multiple first pipelines 20, it reaches the surface of the mating aerostatic bearing body 10 via the mounting hole 11 and the ventilation hole 12, and forms an air film 70 between the aerostatic bearing body 10 and the aerostatic support surface 30. The aerostatic bearing body 10 can slide on the mating aerostatic support surface 30. The gas passes through the flow sensor 40 and the pressure sensor 50 and then enters the horizontal ventilation hole 121 and the vertical ventilation hole 122 of the aerostatic bearing body 10 through the mounting hole 11. The flow sensor 40 and the pressure sensor 50 are arranged close to the mounting hole 11 of the aerostatic bearing body 10, usually within 1 m. A load is applied to the aerostatic bearing body 10 by rotating the threaded ball rod 60, thereby changing the air film gap.

[0047] As Figure 2 shown, when the pressure P 1 is greater than the pressure P 2 , the gas flows in the x direction; the velocity distribution in the y-direction air film cross-section is parabolic, and the gas in contact with each flat plate is stationary ( Figure 2 Source: The first edition in December 1978 - National Defense Industry Press - Design of Aerostatic Bearings).

[0048] Derived from the parameters of the parallel plate air flow:

[0049]

[0050] In the above formula, P 1 , P 2 are the inlet and outlet pressures respectively;

[0051] μ is the fluid viscosity, and RT is a constant;

[0052] l, the length and width of the parallel plate;

[0053] m is the flow rate, and h is the air film gap;

[0054] When the pressure difference is constant, there is a definite relationship between the flow rate m and h. Therefore, the air film gap h can be indirectly measured by measuring the flow rate m.

[0055] Taking a 100-mm circular aerostatic bearing as an example, under a supply air pressure of 0.5 MPa, the relationship curve between the measured flow rate and the air film gap can be used to control the size of the air film gap h by adjusting the flow rate m according to the curve. The specific relationship curve is as Figure 3 shown.

[0056] A method for measuring and adjusting the air film gap of an aerostatic bearing according to an embodiment of the present invention, taking a 100-mm circular aerostatic bearing as an example, includes:

[0057] S1. The air supply pressure source supplies air to the aerostatic bearing body 10 through the first pipeline 20, and the air supply pressure value is read through the pressure sensor 50;

[0058] S2. Rotate the threaded ball rod 70 to apply a load to the air bearing body 10;

[0059] S3. Read the air supply flow rate value through the flow sensor 40;

[0060] S4. The air film gap value can be obtained from the air supply flow rate value; the air film gap value can be calculated through formula (1);

[0061] S5. Repeat steps S2 - S4 until the required air film gap is reached, which conforms to Figure 3 the flow curve of the circular air bearing pad.

[0062] The air bearing is a hydrostatic air bearing with a circular plane, rectangular plane, cylindrical surface, spherical surface, and conical surface. The air bearing can be a small hole throttle, surface throttle, or porous medium throttle bearing.

[0063] Those skilled in the art should understand that the present invention is not limited by the above embodiments. What is described in the above embodiments and the specification only illustrates the principle of the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of protection of the present invention is defined by the appended claims and their equivalents.

Claims

1. A device for measuring and adjusting the air film gap of an air bearing, characterized in that: It comprises an air bearing body (10), a side surface of which is provided with a plurality of mounting holes (11), each mounting hole (11) being connected to one end of a corresponding vent hole (12), and the other end of the vent hole (12) extending to the bottom surface of the air bearing body (10); The air supply end of the mounting hole (11) is connected to an air supply pressure source via a first pipeline (20); a flow sensor (40) is also provided on the first pipeline (20); a pressure sensor (50) is provided between the flow sensor (40) and the mounting hole (11); and the pressure sensor (50) is connected to the first pipeline (20) via a second pipeline (21).

2. The device for measuring and adjusting the air film gap of an air bearing according to claim 1, characterized in that: The vent hole (12) comprises a horizontal vent hole (121) and a vertical vent hole (122), one end of the horizontal vent hole (121) is connected to the air outlet end of the mounting hole (11), the top end of the vertical vent hole (122) is connected to the horizontal vent hole (121), and the bottom end of the vertical vent hole (122) extends to the bottom surface of the air bearing body (10).

3. The device for measuring and adjusting the air film gap of an air bearing according to claim 1, characterized in that: The top surface of the air bearing body (10) is provided with a groove (13), the cross section of the groove (13) is an inverted cone structure, and a threaded ball rod (60) is abutted in the groove (13).

4. The device for measuring and adjusting the air film gap of an air bearing according to claim 1, characterized in that: The flow sensor (40) is an analog sensor or a digital sensor.

5. The device for measuring and adjusting the air film gap of an air bearing according to claim 1, characterized in that: The pressure sensor (50) is an analog sensor or a digital sensor.

6. The method for measuring and adjusting the air film gap of an air bearing according to claim 1, characterized in that: S1, an air supply pressure source supplies air to the air bearing body (10) through a first pipeline (20), and the air supply pressure value is read by a pressure sensor (50); S2, rotating the threaded ball rod (60) to apply a load to the air bearing body (10); S3, reading the gas supply flow value through the flow sensor (40); S4. The air film gap value can be obtained through the air supply flow value; S5. Repeat steps S2-S4 until the desired air film gap is reached.

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