Device and method for measuring static position of air-floating turntable of ultra-precision full-aperture polishing machine

Abstract

The present invention discloses a static position measurement device and method for an air-floating turntable of an ultra-precision, full-aperture polishing machine. The device comprises a supporting air film, a marble polishing turntable, a correction plate, a workpiece plate, a laser displacement sensor, a sensor fixture, a data acquisition card, a high-precision flat crystal, a portable computer, an air supply system, a beam, and a base. The supporting air film is positioned between the marble polishing turntable and the base, and the air supply system supplies air to the supporting air film. The correction plate, workpiece plate, high-precision flat crystal, and beam are all positioned on the marble polishing turntable, and the workpiece is placed on the workpiece plate. The sensor fixture is mounted on the beam, and the laser displacement sensor is fixedly connected to the sensor fixture and electrically connected to the data acquisition card. The data acquisition card is electrically connected to the portable computer. After the laser displacement sensor detects data from the high-precision flat crystal, it is transmitted to the portable computer via the data acquisition card. The air film thickness is tested using a three-point measurement method, solving the problem of difficult static position measurement of large air-floating turntables.

Description

Technical Field

[0001] The present invention belongs to the technical field of ultra-precision large-scale air-floating turntable measurement, and in particular relates to a static position measurement device and method for an ultra-precision full-aperture polishing machine air-floating turntable. Background Art

[0002] A full-aperture polishing machine is a key piece of equipment for processing large-aperture flat optical components. Its primary component is a large-diameter, circular marble polishing turntable with excellent stability and rigidity. Its surface features an asphalt-coated polishing surface with grooves for lubrication and the removal of grinding chips. A correction disc and a workpiece disc are placed on the polishing turntable, one for securing the workpiece and the other for precisely controlling the accuracy of the polishing surface. The polishing turntable's support system is an externally supplied air flotation system. An air supply trough is located at the bottom of the marble polishing turntable, providing an external air pressure of 0.2-0.8 MPa to stably levitate the turntable.

[0003] The polishing turntable is massive, and the workpiece and correction platen also have a certain mass. However, the unevenness and quality of the polishing turntable itself, as well as the uneven positioning of the workpiece and correction plates, can lead to uneven distribution of the air film on the turntable. Furthermore, due to the high compressibility of gas, the flow field may fluctuate. These factors affect static properties such as the air film pressure distribution and load-bearing capacity, reduce turntable stability, and cause changes in the dynamic rotation trajectory. This can lead to changes in the shape error and surface quality of ultra-precision optical workpieces, thus failing to meet operational requirements.

[0004] The static position of a turntable reflects the inherent properties of a machine tool, generally including air film height, turntable deflection angle, and the height and position of its highest and lowest points. It serves as the foundation for static and dynamic analysis of the turntable and plays a key role in controlling machine tool precision. Existing turntable static position measurement devices are primarily focused on small and medium-sized polishing machines and rarely consider the turntable's deflection angle. Position measurement is particularly challenging on full-aperture polishing machines due to the large size and mass of the polishing turntable. Therefore, accurate static position measurement of these large, heavy-duty polishing turntables will enable better analysis and research of their static and dynamic characteristics, providing a theoretical basis for improving the machining quality of optical components. Summary of the Invention

[0005] The purpose of the present invention is to solve the above problems and provide an ultra-precision full-aperture polishing machine air-floating turntable static position measurement device and method that can measure the polishing machine air film height, turntable deflection angle, turntable highest and lowest point height and position.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: an ultra-precision full-aperture polishing machine air-floating turntable static position measuring device, including a supporting air film, a marble polishing turntable, a correction disk, a workpiece disk, a laser displacement sensor, a sensor fixture, a data acquisition card, a high-precision flat crystal, a portable computer, an air supply system, a beam and a base; the supporting air film is located between the marble polishing turntable and the base, the air supply system supplies air to the supporting air film, the correction disk, the workpiece disk, the high-precision flat crystal and the beam are all located on the marble polishing turntable, and the workpiece is placed on the workpiece disk; the sensor fixture is installed on the beam, the laser displacement sensor is fixedly connected to the sensor fixture, and is electrically connected to the data acquisition card, the data acquisition card is electrically connected to the portable computer, and after the laser displacement sensor detects the data of the high-precision flat crystal, it is transmitted to the portable computer through the data acquisition card.

[0007] The present invention also discloses a method for measuring the static position of an air-floating turntable of an ultra-precision full-aperture polishing machine, comprising the following steps:

[0008] S1. When the air-floating turntable is not working, that is, the air supply pressure of the air supply system is zero, three laser displacement sensors are attached to the three beams of the marble polishing turntable through sensor fixtures, and each beam is used as a measurement axis;

[0009] S2, adjusting the position relationship between the laser displacement sensor and the high-precision flat crystal;

[0010] S3. Install a laser displacement sensor on the measuring axis;

[0011] S4. Run the static position measurement device of the air-floating turntable of the ultra-precision full-aperture polishing machine to obtain measurement data.

[0012] Furthermore, in step S2, the probe of the laser displacement sensor is aimed at the high-precision flat crystal placed horizontally below. There are three high-precision flat crystals, and the center of the high-precision flat crystal corresponds to the point below. The three points below are located on the same circle, and the angles between the three points are approximately the same as the angles of the three beams.

[0013] Furthermore, the step S3 further includes the following sub-steps:

[0014] S31. Install a sensor at the 2.3m diameter position on the first measuring axis, measure a 2.3m position point using a caliper, mark it, and align the sensor measurement point before fixing it.

[0015] S32. According to the appropriate angle measured on site, rotate clockwise 125 degrees, install sensor No. 2 at the 2.3m diameter position on the second measuring axis, and align the measuring point of sensor No. 2 with the rotated mark point; rotate clockwise 110 degrees, install sensor No. 3 at the 2.3m diameter position on the third measuring axis, and align the measuring point of sensor No. 3 with the rotated mark point.

[0016] Furthermore, the step S4 further includes the following sub-steps:

[0017] S41. Turn on the air supply system to form a supporting air film between the base and the marble polishing turntable, float the marble polishing turntable, and install the workpiece on the workpiece plate;

[0018] S42. Lower the correction plate when there is air pressure, then release the air, reset the three laser displacement sensors, and set the plane when the air supply pressure is zero as the reference 0 position datum plane;

[0019] S43. Change the gas supply pressure from 0.25 / 0.5 / 0.75 to 0.75 / 0.5 / 0.25 MPa. Repeat this process multiple times. The values of the three points when testing different gas supply pressures are the spatial Z coordinate values. Since the position of the high-precision flat crystal is fixed and will not change, the X and Y coordinates are determined. Check the sensor parameters. The sensor values represent the gas film thickness at different points. The difference between the different conditions represents the change in gas film thickness.

[0020] S44. Find the center of the circle formed by each set of data, calculate the normal vector of the spatial circular surface, and find the angle between the normal vector and the Z coordinate axis vector (0,0,1) to be the turntable deflection angle;

[0021] S45, R are known, through the geometric relationship, the highest and lowest point heights of the turntable can be calculated from the turntable deflection angle;

[0022] S46. A spatial circle is a sphere that is obtained by intercepting a surface of a plane. The equation of the spatial circle is a system of simultaneous equations of the spatial sphere and the spatial plane.

[0023] Furthermore, the simultaneous equations in step S46 are specifically as follows: each set of data in S44 can also form a plane, and the normal vector of the plane is also the normal vector of the spatial circular surface in S44. The three points on the plane are known, and the plane equation can be obtained; the center of the circle obtained in S44 is used as the center of the sphere, and the distance is used as the radius to establish the spherical equation; the plane equation and the spherical equation are combined, and the height values of the highest and lowest points of the turntable obtained in S45 are used as the Z coordinate values, and the X and Y coordinate values, that is, the positions corresponding to the highest and lowest points, can be solved.

[0024] The present invention provides a device for measuring the static position of an ultra-precision, full-aperture polishing machine's air-bearing turntable, featuring a streamlined structure and easy operation. It also provides a "three-point measurement method" for measuring air film thickness. The measurement results reveal the effects of air pressure on air film thickness, turntable deflection angle, and the height and position of the turntable's highest and lowest points. This method addresses the measurement challenges of large air-bearing turntables, and its findings can provide guidance for static and dynamic characterization analysis and performance optimization of air-bearing turntables. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 2. It is a structural schematic diagram of the static position measuring device of the air-floating turntable of the ultra-precision full-aperture polishing machine of the present invention;

[0026] Figure 2 This is a distribution diagram of test installation points of the present invention;

[0027] Figure 3 This is a schematic diagram of the air film thickness measurement result of the present invention;

[0028] Figure 4 Schematic diagram of the highest and lowest points of the turntable according to the measurement results of the present invention;

[0029] Explanation of the accompanying symbols: 1. Air-supporting membrane; 2. Marble polishing turntable; 3. Correction disk; 4. Workpiece disk; 5. Laser displacement sensor; 6. Sensor fixture; 7. Data acquisition card; 8. High-precision flat crystal; 9. Portable computer; 10. Air supply system; 11. Beam; 12. Base. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the accompanying drawings and specific embodiments:

[0031] like Figures 1 to 4 As shown, the static position measurement device for an air-floating turntable of an ultra-precision full-aperture polishing machine provided by the present invention includes a supporting air membrane 1, a marble polishing turntable 2, a correction plate 3, a workpiece plate 4, a laser displacement sensor 5, a sensor fixture 6, a data acquisition card 7, a high-precision flat crystal 8, a portable computer 9, an air supply system 10, a beam 11, and a base 12. The supporting air membrane 1 is located between the marble polishing turntable 2 and the base 12, and the air supply system 10 supplies air to the supporting air membrane 1. The correction plate 3, the workpiece plate 4, the high-precision flat crystal 8, and the beam 11 are all located on the marble polishing turntable 2, and the workpiece is placed on the workpiece plate 4. The sensor fixture 6 is mounted on the beam 11, and the laser displacement sensor 5 is fixedly connected to the sensor fixture 6 and electrically connected to the data acquisition card 7. The data acquisition card 7 is electrically connected to the portable computer 9. After the laser displacement sensor 5 detects data from the high-precision flat crystal 8, the data is transmitted to the portable computer 9 via the data acquisition card 7.

[0032] In this embodiment, the number of laser displacement sensors 5, sensor fixtures 6, and high-precision flat crystals 8 is the same, and the laser displacement sensors 5 are fixed to the beam 11 via the sensor fixtures 6. The laser displacement sensors 5 correspond to the high-precision flat crystals 8 one by one.

[0033] The present invention also discloses a method for measuring the static position of an air-floating turntable of an ultra-precision full-aperture polishing machine, comprising the following steps:

[0034] S1. When the air-floating turntable is not working, that is, the air supply pressure of the air supply system 10 is zero, three laser displacement sensors 5 are respectively adsorbed on three beams 11 of the marble polishing turntable 2 through the sensor fixture 6, and each beam 11 is used as a measuring axis.

[0035] S2. Adjust the positional relationship between the laser displacement sensor 5 and the high-precision flat crystal 8.

[0036] In step S2, the probe of the laser displacement sensor 5 is aimed at the high-precision flat crystal 8 placed horizontally below. There are three high-precision flat crystals 8. The center of the high-precision flat crystal 8 corresponds to the point below. The three points below are located on the same circle, and the angles between the three points are approximately the same as the angles of the three beams 11.

[0037] S3. Install the laser displacement sensor 5 on the measuring axis.

[0038] Step S3 also includes the following sub-steps:

[0039] S31. Install a sensor at the 2.3m diameter position on the first measuring axis. Use a caliper to align and measure a 2.3m position point, mark it, and align the sensor measurement point and then fix it.

[0040] S32. According to the appropriate angle measured on site, rotate clockwise 125 degrees, install sensor No. 2 at the 2.3m diameter position on the second measuring axis, and align the measuring point of sensor No. 2 with the rotated mark point; rotate clockwise 110 degrees, install sensor No. 3 at the 2.3m diameter position on the third measuring axis, and align the measuring point of sensor No. 3 with the rotated mark point.

[0041] S4. Run the static position measurement device of the air-floating turntable of the ultra-precision full-aperture polishing machine to obtain measurement data.

[0042] The principle of this invention is as follows: the sensor value represents the air film thickness. The center of the circle formed by each set of data is found, and the normal vector of the circular surface is calculated. The angle between the normal vector and the Z-axis vector is the turntable deflection angle. Through geometric relationships, the turntable deflection angle is used to calculate the height of the highest and lowest points of the turntable, and thus their positions.

[0043] The step S4 further comprises the following sub-steps:

[0044] S41 , open the air supply system 10 to form a supporting air film 1 between the base 12 and the marble polishing turntable 2 , float the marble polishing turntable 2 , and install the workpiece on the workpiece disk 4 .

[0045] S42. When there is air pressure, lower the correction plate 3, then release all the air, reset the three laser displacement sensors 5, and set the plane when the air supply pressure is zero as the reference 0 position datum plane.

[0046] S43. Change the gas supply pressure from 0.25 / 0.5 / 0.75 to 0.75 / 0.5 / 0.25 MPa. This can be repeated multiple times. The values of the three points when testing different gas supply pressures are the spatial Z coordinate values. Since the position of the high-precision flat crystal 8 will not change after it is determined, the X and Y coordinates are determined. Check the sensor parameters. The sensor values represent the gas film thickness at different points, and the differences in different situations represent the changes in gas film thickness.

[0047] Before changing the gas supply pressure, the laser displacement sensor 5 is connected to the data acquisition card 7, and the data acquisition card 7 is connected to the portable computer 9 to facilitate the collection and processing of data information.

[0048] S44. Find the center of the circle formed by each set of data, calculate the normal vector of the spatial circular surface, and find the angle between the normal vector and the Z coordinate axis vector (0, 0, 1) to be the turntable deflection angle.

[0049] In step S44, the center of each circle formed by each set of data is recorded as (X0, Y0, Z0), and the normal vector is (A, B, C), where X0, Y0, Z0 are the coordinate values of the center of the circle, and A, B, C are the normal vector values.

[0050] S45 and R are known, and through geometric relationships, the height of the highest and lowest points of the turntable can be calculated from the turntable deflection angle.

[0051] S46. A spatial circle is a sphere that is obtained by intercepting a surface of a plane. The equation of the spatial circle is a system of simultaneous equations of the spatial sphere and the spatial plane.

[0052] The simultaneous equations in step S46 are as follows: Each set of data in S44 can also form a plane, and the normal vector of this plane is also the normal vector of the spatial circular surface in S44. Given three points on the plane, the plane equation can be obtained. Using the center of the circle obtained in S44 as the center of the sphere and the distance measured as the radius, the equation of the sphere is established. By combining the plane equation with the sphere equation, and using the height values of the highest and lowest points of the turntable obtained in S45 as the Z coordinate values, the X and Y coordinate values corresponding to the positions of the highest and lowest points can be obtained.

[0053]

[0054] Among them, (X0, Y0, Z0) is the center of the circle and is known, R is the distance measurement and is known, (A, B, C) is the normal vector of the plane and is known, (a, b, c) is a point on the plane and is known, and Z is the height value of the highest and lowest points of the turntable and is known.

[0055] The above formula can be transformed into a set of two-variable equations, and the X and Y values are the positions of the highest and lowest points of the turntable, such as Figure 3 shown.

[0056] Those skilled in the art will appreciate that the embodiments described herein are intended to help readers understand the principles of the present invention, and it should be understood that the scope of protection of the present invention is not limited to such specific descriptions and embodiments. Those skilled in the art can make various other specific variations and combinations based on the technical teachings disclosed in the present invention without departing from the essence of the present invention, and such variations and combinations are still within the scope of protection of the present invention.

Claims

1. The static position measurement method of the air-floating turntable of the ultra-precision full-aperture polishing machine is characterized by: The invention discloses an ultra-precision full-aperture polishing machine air-floating turntable static position measuring device, which comprises a supporting air film (1), a marble polishing turntable (2), a correction plate (3), a workpiece plate (4), a laser displacement sensor (5), a sensor fixture (6), a data acquisition card (7), a high-precision flat crystal (8), a portable computer (9), an air supply system (10), a beam (11) and a base (12); the supporting air film (1) is located between the marble polishing turntable (2) and the base (12); the air supply system (10) is a supporting air film (1) and a beam (11) is a beam (11) and a base (12); the supporting air film (1) is located between the marble polishing turntable (2) and the base (12); the supporting air film (1) is located between the marble polishing turntable (2) and the base (12); the supporting air film (1) is a supporting air film (1) and a beam (11) is a beam (11) and a base (12) The air support film (1) supplies air, the correction disk (3), the workpiece disk (4), the high-precision flat crystal (8) and the beam (11) are all located on the marble polishing turntable (2), and the workpiece is placed on the workpiece disk (4); the sensor fixture (6) is installed on the beam (11), the laser displacement sensor (5) is fixedly connected to the sensor fixture (6), and is electrically connected to the data acquisition card (7), the data acquisition card (7) is electrically connected to the portable computer (9), and after the laser displacement sensor (5) detects the data of the high-precision flat crystal (8), it transmits the data to the portable computer (9) through the data acquisition card (7); The method for measuring the static position of the air-floating turntable of an ultra-precision full-aperture polishing machine includes the following steps: S1. When the air-floating turntable is not working, that is, the air supply pressure of the air supply system (10) is zero, three laser displacement sensors (5) are respectively adsorbed on three beams (11) of the marble polishing turntable (2) through the sensor fixture (6), and each beam (11) is used as a measuring axis; S2, adjusting the positional relationship between the laser displacement sensor (5) and the high-precision flat crystal (8); S3, installing a laser displacement sensor (5) on the measuring axis; S4. Run the static position measurement device of the air-floating turntable of the ultra-precision full-aperture polishing machine to obtain measurement data; In the step S2, the probe of the laser displacement sensor (5) is aimed at the high-precision flat crystal (8) placed horizontally below, the number of the high-precision flat crystals (8) is three, the center of the high-precision flat crystal (8) corresponds to the point below, the three points below are located on the same circle, and the angles between the three points are similar to the angles of the three beams (11); The step S3 further comprises the following sub-steps: S31. Install a sensor at the 2.3m diameter position on the first measuring axis, measure a 2.3m position point using a caliper, mark it, and align the sensor measurement point before fixing it. S32. Based on the appropriate angle measured on site, rotate 125 degrees clockwise and install sensor No. 2 at the 2.3m diameter position on the second measuring axis, aligning the measuring point of sensor No. 2 with the rotated mark. Rotate 110 degrees clockwise and install sensor No. 3 at the 2.3m diameter position on the third measuring axis, aligning the measuring point of sensor No. 3 with the rotated mark. The step S4 further comprises the following sub-steps: S41, opening the air supply system (10), forming a supporting air film (1) between the base (12) and the marble polishing turntable (2), floating the marble polishing turntable (2), and installing the workpiece on the workpiece plate (4); S42, lower the correction plate (3) when there is air pressure, then release the air, reset the three laser displacement sensors (5), and set the plane when the air supply pressure is zero as the reference 0 position datum plane; S43, change the air supply pressure from 0.25 MPa to 0.75 MPa, 0.5 MPa to 0.5 MPa, and 0.75 MPa to 0.25 MPa, and repeat the process several times. The values of the three points when testing different air supply pressures are the spatial Z coordinate values. Since the position of the high-precision flat crystal (8) is fixed and does not change, the X and Y coordinates are determined. Check the sensor parameters. The sensor values represent the thickness of the air film at different points. The difference between the different conditions represents the change in the thickness of the air film. S44. Find the center of the circle formed by each set of data, calculate the normal vector of the circular surface in space, and find the angle between the normal vector and the Z coordinate axis vector (0,0,1) to be the turntable deflection angle; S45, R are known, through the geometric relationship, the highest and lowest point heights of the turntable are calculated from the turntable deflection angle; R is the distance measurement and is known; S46. A spatial circle is a sphere that is obtained by intercepting a surface of a plane. The equation of the spatial circle is a system of simultaneous equations of the spatial sphere and the spatial plane.

2. The method for measuring the static position of an air-floating turntable of an ultra-precision full-aperture polishing machine according to claim 1, wherein: The simultaneous equations in step S46 are specifically as follows: each set of data in S44 can also form a plane, the normal vector of the plane is also the normal vector of the spatial circular surface in S44, and the three points on the plane are known, and the plane equation can be obtained; Use the center of the circle obtained in S44 as the center of the sphere and the measured distance as the radius to establish the spherical equation; combine the plane equation and the spherical equation, and use the height values of the highest and lowest points of the turntable obtained in S45 as the Z coordinate values, and then you can solve for the X and Y coordinate values, which are the positions of the corresponding highest and lowest points.

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