Double-sided polishing machine with high-precision non-contact flexible loading force control

Abstract

The invention provides a double-sided polishing machine with high-precision non-contact flexible loading force control. The double-sided polishing machine comprises a supporting assembly, a polishing assembly, a loading assembly and a control system. The supporting assembly is composed of a base and a portal frame. The polishing assembly is installed on the base. The loading assembly comprises an air cylinder, an air source, an air bearing, a top force transmission disc and a jacking disc. The top force transmission disc is fixed to the polishing assembly, the cylinder is fixed to the portal frame, and a piston rod of the cylinder is hinged to an upper end ball of the air bearing. The air bearing is located above the top force transmission disc, and an exhaust hole is formed in the lower end face of the air bearing. The jacking disc is located between the top force transmission disc and the upper polishing disc and connected with the air bearing through a connecting rod. The air source is used for supplying air to the air cylinder and the air bearing. The control system is used for controlling air conveying work of the air source. Through an air film formed by the air bearing and the top force transmission disc, the loading force of the air cylinder is transmitted to the polishing disc in a non-contact mode, the equipment stability is improved, and the machining precision is ensured.

Description

Technical Field

[0001] The invention relates to the technical field of polishing machines, in particular to a double-sided polishing machine with high-precision non-contact flexible loading force control. Background Art

[0002] In the development of optical engineering, the requirements for optical system performance in various fields are increasing, which has prompted optical components to develop in the direction of high precision and large aperture. Especially in the fields of aerospace and military defense, such as satellite remote sensing imaging systems, high-resolution telescopes, and optical aiming systems for precision-guided weapons, extremely high standards are set for the quality and performance of optical components. In the processing and manufacturing of optical components, polishing is a key step to ensure that these high standards are met.

[0003] However, the traditional single-sided polishing technology has serious drawbacks. Taking the common small tool single-sided polishing as an example, the small tool single-sided polishing requires manual flipping and re-clamping of the workpiece to complete double-sided processing. This method not only increases the processing time, but also causes fluctuations in processing accuracy due to the instability of manual operation, which is difficult to meet the needs of modern optical components for nanometer and even sub-nanometer precision. The emergence of double-sided polishing machine technology provides an effective solution to these problems. The double-sided polishing machine can process the two surfaces of the optical component at the same time in one operation, greatly shortening the processing cycle and improving production efficiency. By accurately controlling the parameters such as the rotation speed, pressure and abrasive flow of the polishing disc, the polishing process can be accurately managed, thereby ensuring the surface quality and shape accuracy of the optical component. In addition, this technology has a high level of automation, reduces the possibility of human intervention, and further improves the stability and consistency of processing.

[0004] However, despite the significant progress made by the double-sided polisher, its design that relies on the loading cylinder to provide the loading force also has limitations. Since the loading cylinder will inevitably come into contact with the rotating upper polishing disc, this will not only affect the precise control of the loading force, but also transmit torque to the loading cylinder, thereby interfering with the overall stability of the equipment. Therefore, in future development, how to optimize this design to further improve the performance of the double-sided polisher is still an important topic worthy of in-depth research. Summary of the invention

[0005] In view of the problem that it is difficult to avoid direct contact between the loading cylinder and the polishing disk in the existing double-sided polishing machines, the present invention provides a double-sided polishing machine with high-precision non-contact flexible loading force control, which uses the air film formed between the air bearing and the top force transmission disk as the transmission medium to transmit the loading force of the cylinder to the upper polishing disk without contact, thereby increasing the stability of the double-sided polishing machine and improving the processing accuracy.

[0006] The present invention achieves the above technical objectives through the following technical means.

[0007] A double-sided polishing machine with high-precision non-contact flexible loading force control, comprising a support assembly, a polishing assembly, a loading assembly and a control system;

[0008] The support assembly includes a base fixed on the workbench, and a gantry fixed on the base;

[0009] The polishing assembly is mounted on the base and is located directly below the gantry;

[0010] The loading assembly includes an air source, a cylinder, an air-floating bearing, a top force transmission disc and a lifting plate; the cylinder is fixed on the gantry, the piston rod of the cylinder is hinged to the upper end ball of the air-floating bearing, the rodless chamber and the rod chamber of the cylinder are respectively provided with a first air vent and a second air vent connected to the air source; the air-floating bearing is provided with a third air vent connected to the air source, and a plurality of exhaust holes are provided on the lower end surface of the air-floating bearing; the top force transmission disc is located between the air-floating bearing and the upper polishing disc in the polishing assembly, and is fixed to the upper polishing disc by a plurality of connecting columns; the lifting plate is located between the top force transmission disc and the upper polishing disc, and is suspended on the lower end surface of the air-floating bearing by a connecting rod vertically passing through the top force transmission disc, and there is no friction between the connecting rod and the top force transmission disc;

[0011] The control system is used to manage the gas delivery of the gas source, and then regulate the working state of the cylinder and the air bearing.

[0012] Furthermore, during polishing, the thickness of the air film formed between the air bearing and the top force transmission disc is 5 to 20 μm; and the length of the connecting rod is greater than the sum of the thicknesses of the top force transmission disc and the air film.

[0013] Furthermore, the exhaust holes are distributed in a circumferential array on the lower end surface of the air bearing, and a plurality of throttling grooves connected to the exhaust holes are also provided on the lower end surface of the air bearing.

[0014] Furthermore, the throttling groove is an annular structure and is distributed on the lower end surface of the air bearing along the radial direction.

[0015] Furthermore, a pressure equalizing groove and a linear groove are provided on the lower end surface of the air floating bearing; the pressure equalizing grooves are distributed on the exhaust holes, each pressure equalizing groove is connected to the middle section of a linear groove, and the inner section of the linear groove leads to the middle part of the lower end surface of the air floating bearing, and the outer section leads to the edge of the lower end surface of the air floating bearing; the depth of the pressure equalizing groove is not less than the depth of the linear groove and the throttling groove.

[0016] Furthermore, it also includes a pressure-stabilizing gas tank, a buffer gas tank A, a buffer gas tank B, a pressure reducing valve and a proportional directional valve A; the output end of the gas source is connected to the input end of the pressure-stabilizing gas tank through the pressure reducing valve; the proportional directional valve A is arranged on the output end of the pressure-stabilizing gas tank, and is connected in parallel with the input ends of the buffer gas tank A and the buffer gas tank B; the output ends of the buffer gas tank A and the buffer gas tank B are respectively connected to the first vent and the second vent; the pressure reducing valve and the proportional directional valve A are controlled to open and close by the control system.

[0017] Furthermore, the control system includes a two-position three-way solenoid valve A, a two-position three-way solenoid valve B, a proportional directional valve B, a high-precision pressure sensor and a host computer; the two-position three-way solenoid valve A and the two-position three-way solenoid valve B are respectively arranged on the connecting pipeline between the proportional directional valve A and the buffer gas tank A, and the connecting pipeline between the proportional directional valve A and the buffer gas tank B; the proportional directional valve B is arranged on the connecting pipeline between the output end of the pressure-stabilizing gas tank and the third air vent; the high-precision pressure sensor is used to detect the pressure values ​​in the rodless chamber and the rod chamber, and send them to the host computer; the host computer is used to control the working state of the air bearing by controlling the opening and closing of the proportional directional valve B, and to control the pressure difference between the rodless chamber and the rod chamber by adjusting the opening of the two-position three-way solenoid valve A and the two-position three-way solenoid valve B, thereby controlling the working state of the cylinder.

[0018] Further, the polishing assembly includes an upper polishing plate, a lower polishing plate, an abrasive fluid distribution plate, an assembly plate, a gear ring, a sun gear, a planetary gear, a spindle and a motor;

[0019] The lower polishing disc, the upper polishing disc and the assembly disc are all provided with a central through hole in the middle, the assembly disc is fixed to the middle of the upper polishing disc, and the aperture of the central through hole on the assembly disc is smaller than the aperture of the central through hole on the upper polishing disc; one end of the spindle is connected to the output shaft of the motor, and the other end passes through the central through hole on the lower polishing disc, the upper polishing disc and the assembly disc in sequence; a gap is left between the lower polishing disc and the spindle, the assembly disc is sleeved on the spindle through a spline fit, and can move axially along the spindle together with the upper polishing disc; the lower polishing disc and the gear The rings are all installed on the base, and the gear ring surrounds the outer edge surface of the lower polishing plate; the sun gear is sleeved on the main shaft and rotates synchronously with it, the planetary gear is placed on the lower polishing plate, the two sides of the planetary gear are respectively meshed with the sun gear and the gear ring, and the planetary gear is provided with a number of limit holes for placing workpieces; the abrasive liquid distribution plate is fixed on the outer edge surface of the top force transmission disc, and a number of through holes A are provided at the bottom of the abrasive liquid distribution plate, and a number of through holes B are provided on the upper polishing plate and the assembly plate, and the through holes A and B are connected by a hose.

[0020] Furthermore, it also includes a ball joint connector having a ball head and a sleeve, wherein the sleeve of the ball joint connector is threadedly connected to one end of the piston rod; a ball head seat hinged to the ball head of the ball joint connector is provided in the middle of the upper surface of the air bearing.

[0021] Furthermore, polishing pads are arranged on the working surfaces of the upper polishing disc and the lower polishing disc; and a buffer pad is arranged on the lower end surface of the top force transmission disc.

[0022] The beneficial effects of the present invention are as follows:

[0023] 1. The present invention uses the air film formed between the air bearing and the top force transmission disc as the loading force transmission medium of the upper polishing disc, and transmits the downward loading force of the cylinder to the upper polishing disc in the polishing assembly in a flexible non-contact manner, effectively avoiding the vibration, wear and the resulting reduction in machining accuracy caused by the direct contact between the cylinder and the polishing disc in the traditional double-sided polishing machine. At the same time, the existence of the air film can also prevent the upper polishing disc from transmitting torque to the cylinder, thereby making the equipment run more smoothly, significantly extending the service life of mechanical components, and reducing the subsequent maintenance costs.

[0024] 2. The present invention realizes uniform distribution and precise control of gas pressure by designing a unique slot structure on the lower end surface of the air bearing, including radially distributed annular throttling grooves, pressure equalizing grooves and linear grooves connected thereto, and cooperates with central exhaust holes and circumferential exhaust holes, thereby effectively improving the stability of the air film and enhancing the uniformity of force transmission.

[0025] 3. The present invention uses a ball joint to connect the piston rod of the cylinder and the air bearing. This design can ensure that the loading force is evenly transmitted to the top force transmission disc below when the polishing assembly is not in a horizontal position due to uneven workpiece thickness or installation error. Compared with the traditional rigid connection method, the ball joint structure can automatically adapt to small angle deviations, ensure the uniformity of pressure distribution during the polishing process, and thus improve the quality consistency of the workpiece surface.

[0026] 4. The lifting plate in the present invention can lift the entire polishing assembly driven by the connecting rod. This design greatly facilitates the picking and replacement of workpieces, optimizes the production process, and improves work efficiency.

[0027] 5. The present invention can flexibly adjust the loading force according to different loading force requirements and adapt to various material and process requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a three-dimensional diagram of the double-sided polishing machine described in the present invention.

[0029] Figure 2 It is a partial cross-sectional view of the double-sided polishing machine described in the present invention.

[0030] Figure 3 It is a schematic diagram of the structure of the loading component (excluding the top force transmission disc).

[0031] Figure 4 Schematic diagram of the connection between the piston rod and the air bearing.

[0032] Figure 5 It is a gas path connection diagram between the gas source and the first vent hole and the second vent hole.

[0033] Figure 6 It is a structural schematic diagram of the lower end surface of the air bearing.

[0034] The reference numerals are as follows:

[0035] 1-base; 2-gantry; 3-cylinder; 4-air bearing; 5-top force transmission disc; 6-lifting disc; 7-hose; 8-throttle groove; 9-pressure equalizing groove; 10-connecting rod; 11-exhaust hole; 12-piston rod; 13-linear groove; 14-upper polishing disc; 15-lower polishing disc; 16-assembly disc; 17-gear ring; 18-sun gear; 19-planetary gear; 20-spindle; 21-limiting hole; 22-grinding fluid distribution disc; 23-pass Hole A; 24-through hole B; 25-first vent hole; 26-second vent hole; 27-third vent hole; 28-ball joint connector; 29-ball head seat; 30-buffer pad; 31-gas source; 32-pressure-stabilizing gas tank; 33-pressure reducing valve; 34-proportional directional valve A; 35-two-position three-way solenoid valve A; 36-two-position three-way solenoid valve B; 37-buffer gas tank A; 38-buffer gas tank B; 39-high-precision pressure sensor; 40-host computer. DETAILED DESCRIPTION

[0036] The present invention is further described below in conjunction with the accompanying drawings and specific embodiments, but the protection scope of the present invention is not limited thereto.

[0037] The double-sided polishing machine with high-precision non-contact flexible loading force control described in this embodiment includes a support component, a polishing component, a loading component and a control system. Figure 1 It is a three-dimensional diagram of the double-sided polishing machine described in this embodiment.

[0038] The support assembly includes a base 1 fixed on the workbench, and a gantry 2 fixed on the base 1 .

[0039] The polishing assembly is mounted on the base 1 and is located directly below the gantry 2, and includes an upper polishing disc 14, a lower polishing disc 15, an assembly disc 16, an abrasive fluid distribution disc 22, a gear ring 17, a sun gear 18, a planetary gear 19, a spindle 20 and a motor. Figure 2It is a partial cross-sectional view of the double-sided polishing machine described in this embodiment. The middle parts of the lower polishing disc 15, the upper polishing disc 14 and the assembly disc 16 are all provided with a central through hole. The assembly disc 16 is fixed to the middle part of the upper polishing disc 14, and the aperture of the central through hole on the assembly disc 16 is smaller than the aperture of the central through hole on the upper polishing disc 14. One end of the main shaft 20 is connected to the output shaft of the motor, and the other end passes through the central through holes on the lower polishing disc 15, the upper polishing disc 14 and the assembly disc 16 in sequence. There is a gap between the lower polishing disc 15 and the main shaft 20, and the assembly disc 16 is sleeved on the main shaft 20 through a spline fit, and can move axially along the main shaft 20 together with the upper polishing disc 14. The abrasive liquid distribution plate 22 is fixed on the outer edge surface of the top force transmission disc 5. A plurality of through holes A23 are provided at the bottom of the abrasive liquid distribution plate 22. A plurality of through holes B24 are provided through the upper polishing disc 14 and the assembly disc 16. The through holes A23 and the through holes B24 are connected by a hose 7. The lower polishing disc 15 and the gear ring 17 are both mounted on the base 1, and the gear ring 17 surrounds the outer edge surface of the lower polishing disc 15. The sun gear 18 is sleeved on the main shaft 20 and rotates synchronously therewith. The planetary gear 19 is placed on the lower polishing disc 15. The two sides of the planetary gear 19 are respectively meshed with the sun gear 18 and the gear ring 17. The planetary gear 19 is provided with a plurality of limit holes 21 for placing workpieces. Polishing pads are provided on the working surfaces of the upper polishing disc 14 and the lower polishing disc 15.

[0040] The loading assembly includes an air source 31, an air cylinder 3, an air bearing 4, a top force transmission disc 5 and a lifting disc 6. Figure 3 The figure is a schematic diagram of the structure of the loading assembly (excluding the top force transmission disc 5) described in this embodiment. The cylinder 3 includes a cylinder body fixed on the gantry 2, a piston slidably mounted in the cylinder body, and a piston rod 12 connected to the piston at one end and ball-jointed to the air bearing 4 at the other end in the vertical direction through a ball joint connector 28. The ball joint connector 28 has a ball head and a sleeve, and the sleeve is threadedly connected to one end of the piston rod 12. A ball head seat 29 is provided in the middle of the upper surface of the air bearing 4, which is articulated to the ball head of the ball joint connector 28. Figure 4 The piston separates the inner cavity of the cylinder into a rodless cavity and a rod cavity, and the inner walls of the rodless cavity and the rod cavity are respectively provided with a first vent hole 25 and a second vent hole 26 connected to the output end pipeline of the air source 31. Figure 5The diagram is a gas circuit connection diagram between the gas source and the first vent and the second vent. As shown in the figure, it also includes a pressure-stabilizing gas tank 32, a buffer gas tank A37, a buffer gas tank B38, a pressure reducing valve 33 and a proportional directional valve A34. The output end of the gas source 31 is connected to the input end of the pressure-stabilizing gas tank 32 through the pressure reducing valve 33. The proportional directional valve A34 is arranged on the output end of the pressure-stabilizing gas tank 32 and is connected in parallel with the input ends of the buffer gas tank A37 and the buffer gas tank B38. The output ends of the buffer gas tank A37 and the buffer gas tank B38 are connected to the first vent 25 and the second vent 26, respectively. The pressure reducing valve 33 and the proportional directional valve A34 are controlled to open and close by the control system. The air bearing 4 is provided with a third vent hole 27 connected to the output end pipeline of the air source 31, and a plurality of exhaust holes 11 are provided on the lower end surface of the air bearing 4. The exhaust holes 11 are distributed in a circular array on the lower end surface of the air bearing 4, and a throttling groove 8, a pressure equalizing groove 9 and a linear groove 13 are also provided on the lower end surface of the air bearing 4. The throttling groove 8 is an annular structure, and is distributed on the lower end surface of the air bearing 4 in the radial direction. The pressure equalizing grooves 9 are distributed on the exhaust hole 11, and each pressure equalizing groove 9 is connected to the middle section of a linear groove 13, and the inner section of the linear groove 13 leads to the middle part of the lower end surface of the air bearing 4, and the outer section leads to the edge of the lower end surface of the air bearing 4; the depth of the pressure equalizing groove 9 is not less than the depth of the linear groove 13 and the throttling groove 8, Figure 6 It is a schematic diagram of the structure of the lower end face of the air bearing. The top force transmission disc 5 is located between the air bearing 4 and the upper polishing disc 14 in the polishing assembly, and is fixed on the upper polishing disc 14 through a number of connecting columns. The lifting disc 6 is located between the top force transmission disc 5 and the upper polishing disc 14, and is suspended on the lower end face of the air bearing 4 through a connecting rod 10 that vertically passes through the middle of the top force transmission disc 5. A threaded hole is provided on the lower end face of the air bearing 4, and an external thread that cooperates with the threaded hole is provided on the upper end of the connecting rod 10. A gap is left between the connecting rod 10 and the top force transmission disc 5. A buffer pad 30 is provided on the lower end face of the top force transmission disc 5. The control system is used to control the loading force output by the cylinder to the outside, and the air supply work of the air bearing 4.

[0041] The control system includes a two-position three-way solenoid valve A35, a two-position three-way solenoid valve B36, a proportional directional valve B, a high-precision pressure sensor 39 and a host computer 40. The two-position three-way solenoid valve A35 and the two-position three-way solenoid valve B36 are respectively arranged on the connecting pipeline between the proportional directional valve A34 and the buffer gas tank A37, and the connecting pipeline between the proportional directional valve A34 and the buffer gas tank B38. The proportional directional valve B is arranged on the connecting pipeline between the output end of the pressure-stabilizing gas tank 32 and the third vent 27. The high-precision pressure sensor 39 is used to detect the pressure values ​​in the rodless cavity and the rod cavity, and send them to the host computer 40. The host computer 40 is used to control the working state of the air bearing 4 by controlling the opening and closing of the proportional directional valve B, and to control the pressure difference between the rodless cavity and the rod cavity by adjusting the opening of the two-position three-way solenoid valve A35 and the two-position three-way solenoid valve B36, thereby controlling the working state of the cylinder 31.

[0042] During polishing, the thickness of the air film formed between the air bearing 4 and the top force transmission disc 5 is 5-20 μm. The length of the connecting rod 10 is greater than the sum of the thickness of the top force transmission disc 5 and the air film.

[0043] The working principle of the double-sided polishing machine with high-precision non-contact flexible loading force control described in this embodiment is as follows:

[0044] When it is necessary to polish the workpiece placed in the limiting hole, first calculate the output force of the required cylinder, that is, the pressure difference between the rod chamber and the rodless chamber. The specific calculation process is as follows:

[0045] Assume that the total weight of the upper polishing disc 14, the top force transmission disc 5, the connecting column, the grinding fluid distribution disc 22 and the hose 7 is G 1 The total weight of the piston rod 12, the air bearing 4, the ball joint 28, the lifting plate 6 and the connecting rod 10 is G 2 , the pressure difference between the rod cavity and the rodless cavity is △F, and the required loading force is F, then △F=FG 1 -G 2 .

[0046] Then the upper computer opens the proportional directional valve B and the two-position three-way solenoid valve A35, and the air source 31 starts to supply air to the air bearing 4 and the rodless cavity. During this period, the two-position three-way solenoid valve B36 is always in a closed state and the exhaust port is connected to the atmosphere. The pressure values ​​in the rodless cavity and the rod cavity are monitored by the high-precision pressure sensor 39. By adjusting the opening of the two-position three-way solenoid valve A35, the pressure difference △F in the rod cavity and the rodless cavity reaches FG 1 -G 2Then start the spindle 20 to start polishing. At this time, the pressure in the rodless chamber is greater than the pressure in the rod chamber. After the work is completed, close the proportional directional valve B and the two-position three-way solenoid valve A35, and connect the exhaust port of the two-position three-way solenoid valve A35 to the atmosphere. Open the two-position three-way solenoid valve B36, and the air source 31 starts to supply air to the rod chamber. By adjusting the opening of the two-position three-way solenoid valve B36, the pressure difference between the rod chamber and the rodless chamber is △F>G 1 +G 2 At this time, the pressure in the rodless chamber is less than the pressure in the rod chamber, and the upper polishing plate 14 rises under the drive of the lifting plate 6, making it convenient for the staff to take out the polished workpiece.

[0047] The embodiments are preferred implementations of the present invention, but the present invention is not limited to the above-mentioned implementations. Any obvious improvements, substitutions or modifications that can be made by those skilled in the art without departing from the essential content of the present invention belong to the protection scope of the present invention.

Claims

1. A double-sided polishing machine with high-precision non-contact flexible loading force control, characterized in that: It includes a supporting assembly, a polishing assembly, a loading assembly and a control system; The support assembly comprises a base (1) fixed on the workbench, and a gantry (2) fixed on the base (1); The polishing assembly is mounted on the base (1) and is located directly below the gantry (2); The loading assembly comprises an air source (31), an air cylinder (3), an air bearing (4), a top force transmission disc (5) and a lifting disc (6); the air cylinder (3) is fixed on the gantry (2); the piston rod (12) of the air cylinder (3) is ball-jointed with the upper end of the air bearing (4); the rodless cavity and the rod cavity of the air cylinder (3) are respectively provided with a first air vent (25) and a second air vent (26) connected to the air source (31); the air bearing (4) is provided with a third air vent (27) connected to the air source (31); and the air bearing (4) is provided with a third air vent (27) connected to the air source (31). A plurality of exhaust holes (11) are provided on the lower end surface of the bearing (4); the top force transmission disc (5) is located between the air-floating bearing (4) and the upper polishing disc (14) in the polishing assembly, and is fixed on the upper polishing disc (14) through a plurality of connecting columns; the lifting disc (6) is located between the top force transmission disc (5) and the upper polishing disc (14), and is suspended on the lower end surface of the air-floating bearing (4) through a connecting rod (10) vertically passing through the top force transmission disc (5), and there is no friction between the connecting rod (10) and the top force transmission disc (5); The control system is used to manage the gas delivery of the gas source (31), thereby regulating the working state of the cylinder (31) and the air bearing (4).

2. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 1, characterized in that: During polishing, the thickness of the air film formed between the air bearing (4) and the top force transmission disc (5) is 5 to 20 μm; the length of the connecting rod (10) is greater than the sum of the thicknesses of the top force transmission disc (5) and the air film.

3. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 1, characterized in that: The exhaust holes (11) are distributed in a circumferential array on the lower end surface of the air bearing (4), and a plurality of throttling grooves (8) connected to the exhaust holes (11) are also provided on the lower end surface of the air bearing (4).

4. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 3, characterized in that: The throttling groove (8) is an annular structure and is distributed on the lower end surface of the air bearing (4) along the radial direction.

5. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 3, characterized in that: The lower end surface of the air-floating bearing (4) is also provided with a pressure-equalizing groove (9) and a linear groove (13); the pressure-equalizing grooves (9) are distributed on the exhaust hole (11), and each pressure-equalizing groove (9) is connected to the middle section of a linear groove (13), and the inner section of the linear groove (13) leads to the middle part of the lower end surface of the air-floating bearing (4), and the outer section leads to the edge of the lower end surface of the air-floating bearing (4); the depth of the pressure-equalizing groove (9) is not less than the depth of the linear groove (13) and the throttling groove (8).

6. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 1, characterized in that: It also includes a pressure-stabilizing gas tank (32), a buffer gas tank A (37), a buffer gas tank B (38), a pressure reducing valve (33) and a proportional directional valve A (34); the output end of the gas source (31) is connected to the input end of the pressure-stabilizing gas tank (32) through the pressure reducing valve (33); the proportional directional valve A (34) is arranged on the output end of the pressure-stabilizing gas tank (32) and is connected in parallel with the input ends of the buffer gas tank A (37) and the buffer gas tank B (38); the output ends of the buffer gas tank A (37) and the buffer gas tank B (38) are respectively connected to the first vent hole (25) and the second vent hole (26); the pressure reducing valve (33) and the proportional directional valve A (34) are controlled to open and close by a control system.

7. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 6, characterized in that: The control system comprises a two-position three-way solenoid valve A (35), a two-position three-way solenoid valve B (36), a proportional directional valve B, a high-precision pressure sensor (39) and a host computer (40); the two-position three-way solenoid valve A (35) and the two-position three-way solenoid valve B (36) are respectively arranged on the connecting pipeline between the proportional directional valve A (34) and the buffer gas tank A (37), and the connecting pipeline between the proportional directional valve A (34) and the buffer gas tank B (38); the proportional directional valve B is arranged on the output of the pressure-stabilizing gas tank (32). The high-precision pressure sensor (39) is used to detect the pressure values ​​in the rodless chamber and the rod chamber, and send them to the host computer (40); the host computer (40) is used to control the working state of the air bearing (4) by controlling the opening and closing of the proportional directional valve B, and to control the pressure difference between the rodless chamber and the rod chamber by adjusting the opening of the two-position three-way solenoid valve A (35) and the two-position three-way solenoid valve B (36), thereby controlling the working state of the cylinder (31).

8. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 1, characterized in that: The polishing assembly comprises an upper polishing disc (14), a lower polishing disc (15), an abrasive fluid distribution disc (22), an assembly disc (16), a gear ring (17), a sun gear (18), a planetary gear (19), a main shaft (20) and a motor; The lower polishing disc (15), the upper polishing disc (14) and the assembly disc (16) are all provided with a central through hole in the middle, the assembly disc (16) is fixed to the middle of the upper polishing disc (14), and the aperture of the central through hole on the assembly disc (16) is smaller than the aperture of the central through hole on the upper polishing disc (14); one end of the main shaft (20) is connected to the output shaft of the motor, and the other end passes through the central through holes on the lower polishing disc (15), the upper polishing disc (14) and the assembly disc (16) in sequence; a gap is left between the lower polishing disc (15) and the main shaft (20), the assembly disc (16) is sleeved on the main shaft (20) through a spline fit, and can move axially along the main shaft (20) together with the upper polishing disc (14); the lower polishing disc (15) and the gear ring (17) are both installed On the base (1), a gear ring (17) surrounds the outer edge surface of the lower polishing disc (15); the sun gear (18) is sleeved on the main shaft (20) and rotates synchronously therewith; the planetary gear (19) is placed on the lower polishing disc (15); the two sides of the planetary gear (19) are respectively meshed with the sun gear (18) and the gear ring (17); the planetary gear (19) is provided with a plurality of limit holes (21) for placing workpieces; the grinding liquid distribution disc (22) is fixed on the outer edge surface of the top force transmission disc (5); the bottom of the grinding liquid distribution disc (22) is provided with a plurality of through holes A (23); the upper polishing disc (14) and the assembly disc (16) are provided with a plurality of through holes B (24); the through holes A (23) and the through holes B (24) are connected by a hose (7).

9. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 1, characterized in that: It also includes a ball joint connector (28) having a ball head and a sleeve, wherein the sleeve of the ball joint connector (28) is threadedly connected to one end of the piston rod (12); a ball head seat (29) hingedly connected to the ball head of the ball joint connector (28) is provided in the middle of the upper surface of the air bearing (4).

10. The double-sided polishing machine with high-precision non-contact flexible loading force control according to claim 1, characterized in that: Polishing pads are arranged on the working surfaces of the upper polishing disc (14) and the lower polishing disc (15); and a buffer pad (30) is arranged on the lower end surface of the top force transmission disc (5).

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