Ultra-precision air static pressure rotary table

Abstract

The application discloses an ultra-precision air static pressure rotary table, which comprises a radial brass bearing sleeve, a table top, a base, a feedback grating system, an axial thrust, a gas distribution block and an air bearing core. The application has the advantages that: for the 300mm nominal disc diameter specification, the four core performance requirements of focusing low speed / low-medium speed operation, large load bearing, ultra-high structural rigidity and nanometer level rotation accuracy can be met, and the application can be widely applied to 300mm semiconductor wafer detection and calibration platforms, optical element ultra-precision grinding / polishing machine tools, diamond tool ultra-precision cutting rotary tables, large-size part high-precision measurement detection instruments, micro-nano manufacturing system rotary tables, aerospace precision component processing equipment and other national strategic high-end manufacturing equipment. The application is a core basic component for supporting modern ultra-precision machining, semiconductor detection, optical manufacturing and precision measurement industry to realize low-speed stable operation, heavy load support, high rigidity precision protection and nanometer level positioning.

Description

Technical Field

[0001] This invention relates to a turntable, specifically an ultra-precision air static pressure turntable, belonging to the technical field of core rotary support functional components for high-end ultra-precision equipment. Background Technology

[0002] An air-static pressure turntable is a non-contact rotary support component that uses clean compressed air as the fluid lubrication medium. Its core working mechanism is based on the theory of hydrostatic lubrication: high-pressure clean gas supplied externally is limited and stabilized by a throttling element, and then uniformly enters the micron-level air film gap between the fixed support and rotating parts of the turntable. This forms a static pressure air film with high load-bearing stiffness, high stability, and high uniformity, completely physically isolating the rotating and fixed parts, achieving ultra-precision rotary motion without mechanical contact, friction, wear, or vibration. The stiffness characteristics, pressure field distribution, and dynamic stability of the air film directly determine the turntable's load-bearing capacity, operational smoothness, and rotational accuracy, and are the core performance determinants of an ultra-precision air-bearing turntable.

[0003] The core requirements for 300mm diameter ultra-precision air-bearing turntables in the current high-end manufacturing sector have shifted from traditional high-speed operation to specialized requirements such as stable low / medium-low speed rotation, large tonnage load capacity, ultra-high rigidity across all dimensions, and continuous nanometer-level precision. Core applications such as semiconductor wafer inspection, optical mirror processing, and precision metrology calibration do not require high-speed operation; instead, they place extreme demands on the turntable's low-speed stability, high axial load capacity, structural deformation resistance, and nanometer-level rotational error control. This is also the industry's recognized core direction for technological research and development.

[0004] However, in existing technologies, the current 300mm diameter ultra-precision air hydrostatic turntables, both domestically and internationally, generally adopt a traditional structure with a central axis rotation and an outer casing fixation. The air bearing support surface is mostly designed with symmetrical upper and lower equal areas. Both the rotating base and the support base are integrally machined from metal materials such as aluminum alloy and stainless steel, requiring ultra-precision grinding and polishing of the full-size air bearing mating surfaces. The overall technical solution has many insurmountable bottlenecks, especially in adapting to core working conditions requiring low / medium-low speed, high load capacity, ultra-high rigidity, and nanometer-level precision. 1. The structural layout and working conditions are extremely poor. The rotational inertia of the traditional central shaft rotating structure is concentrated on the central rotating shaft. When running at low / medium-low speed, problems such as rotational vibration, swaying, and crawling are likely to occur, and the stability cannot meet the requirements of ultra-precision. In addition, the central shaft support area is small, and the axial, radial, and torsional rigidity is inherently insufficient. Under heavy load conditions, the air film is prone to collapse and stiffness reduction, and it is impossible to achieve stable support under heavy load.

[0005] 2. The air flotation design is unreasonable, with insufficient load-bearing and rigidity. The symmetrical air flotation support structure with equal area at the top and bottom is not optimized for the large axial load requirements. The effective air flotation support area is too small, and the axial load-bearing capacity is weak, which cannot meet the processing and inspection requirements of large-size and heavy workpieces. The full circumferential air film coverage is insufficient, and the overall rigidity of the turntable is difficult to reach the ultra-high rigidity standard. The resistance to off-center load, impact, and external vibration interference is extremely poor.

[0006] 3. The core machining process bottleneck cannot be overcome. The inner top surface of the rotating outer sleeve is the key working surface of the axial main load-bearing air bearing. It is a difficult-to-machine structure with a deep cavity and thin wall overhang. When the industry tries to use vertical precision grinding, it faces fatal problems such as difficulty in inserting the grinding head, easy deformation of the clamping, excessive flatness and parallelism of the end face, extremely high scrap rate, extremely low processing efficiency, and high labor and time costs. It has become the core process problem restricting the mass production of 300-diameter rotary tables.

[0007] 4. Accuracy and thermal stability are difficult to meet the standards. Traditional integral metal structures do not have dedicated heat dissipation and precision protection designs. During operation, heat accumulation can easily cause thermal deformation, resulting in a continuous decrease in rotational accuracy. There is no buffer protection mechanism for mating surfaces. Accidental loss of air or instantaneous contact can easily scratch the shaft core, causing the core components to be scrapped. Rotational error cannot be stably controlled at the nanometer level, making it difficult to meet the extreme precision requirements of semiconductor and optical processing.

[0008] 5. High manufacturing costs and difficulty in mass production: The full-size ultra-precision grinding process is lengthy, the processing equipment requirements are stringent, the yield rate is low, the production cycle is long, and the overall production cost remains high, making it impossible to achieve large-scale industrial mass production, which seriously restricts the cost control and market promotion of high-end equipment. Summary of the Invention

[0009] The purpose of this invention is to provide an ultra-precision air hydrostatic turntable to solve at least one of the aforementioned technical problems. This invention addresses the industry pain point that existing 300mm diameter ultra-precision air hydrostatic turntables cannot adapt to core operating conditions requiring low / medium-low speed, high load capacity, ultra-high rigidity, and nanometer-level precision. Based on the fundamental theories of air hydrostatic lubrication, optimization theories of large-size rotary support structures, and precision manufacturing processes, this invention aims to completely overcome the technical limitations of traditional structures and processes, solving the problems of vibration, swaying, and poor stability during low / medium-low speed operation of traditional turntables. It achieves vibration-free, creep-free, and ultra-stable rotary motion under low / medium-low speed conditions; overcomes the technical bottlenecks of weak axial load capacity and air film collapse under high loads in traditional turntables, significantly improving the high load capacity performance of the turntable and meeting the support requirements of heavy-duty workpieces; and breaks through the limitations of traditional... Overcoming the structural rigidity deficiency, this system achieves ultra-high rigidity across the entire axial, radial, and torsional dimensions of the turntable, enhancing its resistance to eccentric loading, impact, and vibration. It eliminates rotational error fluctuations, stabilizing the turntable's radial runout, end face runout, and positioning accuracy at the nanometer level, meeting the extreme precision requirements of ultra-precision machining and testing. It overcomes the industry bottleneck of machining the deep cavity on the inner top surface of the rotating outer sleeve by employing vertical precision grinding technology to achieve high-precision forming, balancing machining accuracy, production efficiency, and mass production feasibility. It solves problems such as poor thermal stability, easy damage to mating surfaces, and lack of shaft protection during turntable operation, improving the turntable's long-term reliability and accuracy retention. Finally, it simplifies the overall manufacturing process, reduces the difficulty of ultra-precision machining, shortens the production cycle, and lowers manufacturing costs, enabling large-scale industrial mass production of a 300mm diameter dedicated air-bearing turntable.

[0010] The present invention achieves the above objectives through the following technical solution: an ultra-precision air static pressure turntable, including a base, the base being an integral support base, an air bearing core rigidly fixed in the center of the base, and a table surface sleeved on the outside of the air bearing core; The base is equipped with a direct drive motor; the table is the main rotating load-bearing body, and the inner wall of the table is bonded with a radial brass bearing sleeve by epoxy resin in the whole circumference. The lower end face of the table is rigidly connected to the axial thrust, and the rotating spindle of the table is rigidly connected to the output end of the direct drive motor. The air bearing core has air passages in the inner radial and axial directions. The radial brass bearing sleeve and the outer circle of the air bearing core form a radial air bearing fit pair. The axial thrust and the axial end face of the air bearing core form an axial air bearing fit pair. A throttle is embedded in the air passages of the air bearing core. A feedback grating system is provided on the outer periphery of the axial thrust.

[0011] As a further aspect of the present invention: the radial brass bearing sleeve is made of refined brass material, the mating surface of the radial brass bearing sleeve and the air bearing core is subjected to ultra-precision grinding treatment, the radial inner circular surface of the radial brass bearing sleeve and the air bearing core form a micron-level radial air film mating gap, and the bonding area between the radial brass bearing sleeve and the inner wall of the platform forms an airtight and flat high-strength epoxy resin bonding layer.

[0012] As a further embodiment of the present invention: the table is made of high-grade nitrided steel through ultra-precision machining, the top of the table is a 300mm standard diameter bearing plate, and the plate is equipped with a workpiece clamping and positioning structure; the inner top surface of the table is an axial main bearing air-bearing working surface, which is formed by integrated ultra-precision grinding on a high-precision vertical grinding machine.

[0013] As a further aspect of the present invention: the base is made of high-rigidity, high-stability high-quality cast iron through precision machining, and the base is rigidly fixed to each component through fastening bolts.

[0014] As a further embodiment of the present invention: a motor mount is fixedly connected inside the base, the motor mount is located in the outer cavity of the air bearing core, and the direct drive motor is installed inside the motor mount.

[0015] As a further aspect of the present invention: the axial thrust is made of high-grade nitrided steel, the mating surface of the axial thrust and the direct drive motor is subjected to ultra-precision grinding, and the axial thrust is rigidly connected to the lower end face of the table rotating spindle, forming a micron-level axial air film mating gap between the thrust and the axial thrust end face of the air bearing core.

[0016] As a further embodiment of the present invention: an air distribution block is installed at the outer air passage interface of the base. The air distribution block is made of stainless steel precision machining. The air distribution block integrates a filtering, pressure stabilizing and flow distribution structure. The air passage channel opened inside the air bearing core is a radial and axial independent air passage. The air distribution block is airtightly connected to the radial and axial independent air passage channels inside the air bearing core.

[0017] As a further embodiment of the present invention: the feedback grating system includes a grating ruler and a reading head. The base is provided with a reading head seat, which is made of high-rigidity structural steel through precision machining. The reading head seat is fixed to the side mounting position of the base by fastening bolts. The grating ruler is mounted on the outer circumference of the table surface, and the reading head is mounted on the reading head seat. The grating ruler and the reading head form a non-contact detection cooperation.

[0018] As a further aspect of the present invention: the air bearing core is made of high-rigidity, low-deformation high-grade nitrided steel through ultra-precision machining. The air bearing core is rigidly fixed to the center of the base by fastening bolts. Throttling devices are embedded in the air bearing core at corresponding radial and axial mating positions. The throttle devices are connected to the independent radial and axial air passages inside the air bearing core. The throttle devices adopt a high-precision small-hole throttling structure. The throttle devices achieve integrated airtight fixation through a sealing structure.

[0019] As a further embodiment of the present invention: an electrical box is fixedly installed on the outermost end face of the base. The electrical box integrates motor driver wiring, grating signal wiring, and pneumatic control wiring, and the electrical box is connected to the feedback grating system and the direct drive motor in a circuit.

[0020] The beneficial effects of this invention are: 1) This invention adopts a unique layout with a centrally fixed air-bearing spindle and a rotating outer sleeve, which optimizes the distribution of rotational inertia from the structural root, completely solving the industry problems of shaking, swaying, and crawling of traditional turntables at low / medium-low speeds. The air film damping characteristics further enhance stability. The turntable has no vibration, no interference, and no precision fluctuation when rotating at low / medium-low speeds, and the running stability reaches the best level in the industry, which fully matches the low-speed stable operation requirements of semiconductor testing and optical processing. 2) This invention adopts an asymmetrical air-floating support structure, which significantly increases the working area of ​​the air-floating surface on the main load-bearing surface and improves the axial load-bearing capacity by more than 30% compared with the traditional symmetrical structure. It can easily support large-sized and heavy workpieces. Under heavy load conditions, the air film does not collapse or its stiffness does not decrease. The air film pressure is adaptively adjusted to maintain a stable support state and fully meet the core usage requirements of heavy load-bearing. 3) This invention adopts a large-area air film covering support in the full circumference, and the axial rigidity, radial rigidity and torsional rigidity of the turntable are all-round breakthroughs, reaching the ultra-high rigidity standard; it has extremely strong resistance to eccentric load, impact and external vibration interference. Even under complex working conditions, the turntable structure is not deformed and the air film is not disturbed. The accuracy retention is far superior to the traditional air-bearing turntable, providing a solid rigidity guarantee for nanometer-level precision. 4) This invention adopts a vertical precision grinding process for the inner top surface of the rotating outer sleeve and an ultra-precision fit with the embedded brass sleeve. The uniformity of the air film gap reaches the nanometer level. The radial runout, end face runout, and positioning accuracy of the turntable are all stably controlled within the nanometer range. It can perfectly support scenarios with extreme precision requirements such as semiconductor wafer calibration, ultra-precision processing of optical mirrors, and precision metrology and testing, filling the technological gap of 300mm diameter nanometer precision air-bearing turntable in China. 5) This invention addresses the industry bottleneck of difficult machining of the deep cavity on the inner top surface of the rotating outer sleeve by employing an integrated ultra-precision grinding process on a high-precision vertical grinding machine, combined with a special non-deformation clamping fixture, to achieve nanometer-level precision forming of the end face in one go. This solves the problems of easy deformation, poor precision, low efficiency, and time-consuming labor in traditional machining. The machining consistency is greatly improved, the scrap rate is reduced to a minimum, the production cycle is shortened by more than 50% compared with traditional processes, and the feasibility of mass production is significantly enhanced. 6) The embedded brass sleeve in this invention has high thermal conductivity, which can quickly dissipate operating heat, suppress thermal deformation, and ensure long-term stable operating accuracy; the brass material is warm and wear-resistant, and has excellent affinity with the shaft core. Under extreme working conditions such as accidental air loss or instantaneous contact, only the brass mating surface is worn, and the high-precision shaft core will never be damaged, achieving ultimate protection for the core components; the adhesive structure is firm and stable, with no falling off or loosening, and the service life and reliability of the turntable far exceed those of traditional products; 7) This invention adopts a small-size brass sleeve ultra-precision machining and bonding process to replace the overall ultra-precision grinding of the rotating outer sleeve, which greatly reduces the ultra-precision machining area and process difficulty, and significantly reduces the investment in processing equipment, production time and overall manufacturing cost; while ensuring the core performance of low speed / medium-low speed, large load, ultra-high rigidity and nanometer-level precision, it realizes the efficient, low-cost and large-scale industrial mass production of 300mm disc diameter ultra-precision air-bearing turntable.

[0021] In summary, this invention is specifically designed for low / medium-low speed, high load capacity, ultra-high rigidity, and nanometer-level precision. It abandons redundant high-speed functions and focuses on core requirements. It can comprehensively cover all categories of high-end ultra-precision equipment such as 300mm wafer inspection, optical component processing, precision metrology, micro-nano manufacturing, and aerospace precision machining. It achieves a perfect balance between versatility and specialization, and its industrial application value is extremely outstanding. Attached Figure Description

[0022] Fig. 1 This is a schematic diagram of the overall structure of the present invention; Fig. 2 This is a schematic diagram of the cross-sectional structure of the present invention; Fig. 3 This is a schematic diagram of the disassembled structure of the present invention; Fig. 4 This is a schematic diagram of the air bearing core structure of the present invention; In the diagram: 1. Radial brass bearing sleeve; 2. Tabletop; 3. Base; 4. Motor mount; 5. Feedback grating system; 51. Grating ruler; 52. Reading head; 6. Axial thrust; 7. Direct drive motor; 8. Air distribution block; 9. Air bearing core; 91. Air passage; 10. Throttling device; 11. Reading head mount; 12. Electrical box. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] Example 1, as Figs. 1 to 4 As shown, this embodiment provides an ultra-precision air static pressure turntable, including a base 3, which is an integral support base. An air bearing core 9 is rigidly fixed in the center of the base 3, and a table surface 2 is sleeved on the outside of the air bearing core 9. The base 3 is equipped with a direct drive motor 7; the platform 2 is the main rotating load-bearing body, and the inner wall of the platform 2 is bonded with a radial brass bearing sleeve 1 by epoxy resin in the whole circumference. The lower end face of the platform 2 is rigidly connected to the axial thrust 6, and the rotating spindle of the platform 2 is rigidly connected to the output end of the direct drive motor 7. The air bearing core 9 has air passages 91 in the inner radial and axial directions. The radial brass bearing sleeve 1 and the outer circle of the air bearing core 9 form a radial air bearing fit pair. The axial thrust 6 and the axial end face of the air bearing core 9 form an axial air bearing fit pair. A throttle 10 is embedded in the air passages 91 of the air bearing core 9. A feedback grating system 5 is provided on the outer periphery of the axial thrust 6.

[0025] Example 2: In addition to all the technical features in Example 1, this example also includes: the radial brass bearing sleeve 1 is made of refined brass; the mating surfaces of the radial brass bearing sleeve 1 and the air bearing core 9 are subjected to ultra-precision grinding; a micron-level radial air film mating gap is formed between the radial inner circular surfaces of the radial brass bearing sleeve 1 and the air bearing core 9; and a high-strength epoxy resin adhesive layer is formed at the bonding point between the radial brass bearing sleeve 1 and the inner wall of the table 2. The radial brass bearing sleeve 1 is made of warm and wear-resistant brass, which has excellent compatibility with the air bearing core 9, and can achieve ultimate protection for the air bearing core 9, while ensuring the uniformity and stability of the radial air film gap, providing high-rigidity radial air buoyancy support for the turntable.

[0026] The table 2 is made of high-grade nitrided steel through ultra-precision machining. The top of the table 2 is a 300mm standard diameter bearing plate, and the plate is equipped with a workpiece clamping and positioning structure to fix large-sized and heavy workpieces to be processed and inspected. The inner top surface of the table 2 is the axial main bearing air-bearing working surface, which is formed by high-precision vertical grinding machine integrated ultra-precision grinding. It is clamped by special thin-walled non-deformation tooling fixtures to complete the sub-micron level precision machining of the end face flatness, parallelism and perpendicularity in one go, ensuring the nanometer level precision foundation of the air-bearing working surface from the process source.

[0027] The base 3 is made of high-rigidity, high-stability high-quality cast iron through precision machining. The base 3 is rigidly fixed to each component through fastening bolts, providing a precise installation benchmark and rigid support for all core components of the turntable, effectively suppressing vibration and deformation during turntable operation, and ensuring the long-term stability and precision of the overall structure of the turntable.

[0028] A motor mount 4 is fixedly connected inside the base 3. The motor mount 4 is located in the outer chamber of the air bearing core 9. The direct drive motor 7 is installed in the motor mount 4. The motor mount 4 provides precise installation positioning and rigid support for the direct drive motor 7, ensuring the coaxiality of the direct drive motor 7 and the table 2, and eliminating transmission eccentricity error. It provides direct drive rotational power to the table 2 without intermediate transmission. It should be noted that the direct drive motor 7 adopts a high-performance direct drive torque motor with high torque, high speed, high response, and low heat generation characteristics. It can realize stepless speed regulation and precise drive of the turntable, meet the rotational power requirements of ultra-precision machining and testing, and effectively improve the dynamic performance and operating efficiency of the turntable.

[0029] The axial thrust 6 is made of high-grade nitrided steel. The mating surfaces of the axial thrust 6 and the direct drive motor 7 are treated with ultra-precision grinding. The axial thrust 6 is rigidly connected to the lower end face of the rotating spindle of the table 2. A micron-level axial air film mating gap is formed between the axial thrust end face of the thrust 6 and the air bearing core 9. This can effectively withstand the axial load of the turntable, ensure the stability of the axial air film gap, provide high-rigidity axial air float support for the turntable, and work together with the radial air float structure to achieve full-degree-of-freedom suspension of the turntable.

[0030] An air distribution block 8 is installed at the outer air passage interface of the base 3. The air distribution block 8 is made of stainless steel precision machining. The air distribution block 8 integrates a filtration, pressure stabilization and flow distribution structure. The air passage 91 opened inside the air bearing core 9 is a radial and axial independent air passage. The air distribution block 8 is airtightly connected to the radial and axial independent air passage 91 inside the air bearing core 9. This provides a stable supply of clean and stable high-pressure air to the air flotation support system, avoids impurities from clogging the throttle 10, and ensures the long-term stable operation of the air membrane.

[0031] The feedback grating system 5 includes a grating ruler 51 and a reading head 52. A reading head seat 11 is installed inside the base 3. The reading head seat 11 is made of high-rigidity structural steel and is precision machined. The reading head seat 11 is fixed to the side mounting position of the base 3 by fastening bolts. The grating ruler 51 is mounted on the outer circumference of the platform 2, and the reading head 52 is mounted on the reading head seat 11. The grating ruler 51 and the reading head 52 form a non-contact detection cooperation. The reading head seat 11 provides precise installation positioning and rigid support for the reading head 52, ensuring the relative position accuracy between the reading head 52 and the grating ruler 51, improving the accuracy and reliability of grating detection, and acquiring the rotation angle and position signal of the platform 2 in real time to achieve nanometer-level angle positioning accuracy for closed-loop control of the rotation speed and position of the platform 2.

[0032] The air bearing core 9 is made of high-rigidity, low-deformation high-grade nitrided steel through ultra-precision machining. The air bearing core 9 is rigidly fixed to the center of the base 3 by fastening bolts. Throttling devices 10 are embedded in the air bearing core 9 at corresponding radial and axial mating positions. The throttle devices 10 are connected to the independent radial and axial air passages 91 inside the air bearing core 9. The air bearing core 9 provides the core air passage carrier and mating reference for the turntable air bearing support system, ensuring the uniformity, stability and high rigidity of the air film. After the radial gas is limited and stabilized by the throttle device 10, a continuous, uniform and high-rigidity radial static pressure air film is formed between the radial brass bearing sleeve 1 and the air bearing core 9. The axial gas is precisely throttled out by the throttle device 10, forming a rapid-response and highly anti-interference axial static pressure air film between the axial thrust 6 and the air bearing core 9. Two types of air films work together to completely suspend the platform 2, achieving ultra-precision rotation without mechanical contact, friction, wear, or heat generation. When the platform 2 is subjected to radial and axial loads, the air film pressure adaptively adjusts with the gap to maintain pressure balance and air film stability, significantly improving the overall rigidity and load-bearing capacity of the turntable. The throttle 10 adopts a high-precision small-orifice throttling structure. The throttle 10 achieves integrated airtight fixation through a sealing structure, limiting and stabilizing the high-pressure gas to ensure stable gas pressure and uniform flow rate entering the air-float mating gap. This structurally solves the technical problems of inconsistent flow resistance and uneven gas output in radial and axial coupling throttling, providing precise throttling control for air film formation and improving the stability and rigidity of the air-float support.

[0033] An electrical box 12 is fixedly installed on the outermost end face of the base 3. The electrical box 12 integrates the motor driver wiring, grating signal wiring, and pneumatic control wiring. The electrical box 12 is connected to the feedback grating system 5 and the direct drive motor 7 in a circuit, providing integrated electrical integration for the turntable and realizing the external connection and operation and maintenance management of the turntable's circuit, pneumatic circuit, and signal.

[0034] Clean compressed gas, after being externally treated by pressure stabilization, purification, and drying, is introduced into the gas distribution block 8. After being stabilized and filtered by the gas distribution block 8, it is introduced into the mutually isolated radial and axial independent gas paths inside the air bearing core 9. Inside the air bearing core 9, the gas is limited and stabilized by throttles 10 embedded in the corresponding gas path positions. The radial gas, after passing through the throttle 10, enters the radial air-float fit gap between the radial brass bearing sleeve 1 and the air bearing core 9, forming a continuous, uniform, and highly rigid radial static pressure gas film between the inner circular surface of the radial brass bearing sleeve 1 and the outer circular surface of the air bearing core 9. The axial gas, after passing through the throttle 10, enters the axial air-float fit gap between the axial thrust 6 and the air bearing core 9, and the axial thrust 6... A stable and balanced axial static pressure air film is formed between the end face and the axial thrust end face of the air bearing core 9. The radial static pressure air film and the axial static pressure air film work together to suspend and lift the platform 2 completely without contact, so that the platform 2 and the air bearing core 9 are in a completely isolated non-contact state. At the same time, since the radial brass bearing sleeve 1 is fixed to the inner wall of the platform 2 in the full circumferential area by adhesive bonding and a micron-level gap is formed between its inner circular surface and the outer circular surface of the air bearing core 9, the axial thrust 6 is rigidly connected to the lower end face of the platform 2 and a micron-level gap is formed between its lower end face and the axial thrust end face of the air bearing core 9. The pressure of the air film is adaptively adjusted according to the radial load or axial load borne by the platform 2 to maintain pressure balance and air film stability. When the platform 2 bears a large axial load, the upper and lower asymmetrical air-bearing support structure formed by the area of ​​the inner top surface of the platform 2 as the main axial load-bearing air-bearing working surface is larger than the area of ​​the inner circular surface of the radial brass bearing sleeve 1. This provides the maximum support area for the main load-bearing air-bearing working surface. The full circumferential air film full coverage support greatly improves the air film stiffness and load-bearing capacity, thereby achieving ultra-high rigidity in all dimensions. When the platform 2 rotates at low speed or medium-low speed, the air-bearing bearing core 9 is fixed to the center of the base 3, and the platform 2, as the main rotating load-bearing body, is sleeved on the outside of the air-bearing bearing core 9 and rotates with the direct drive motor 7. The rotational inertia is evenly distributed in the platform 2 and the air film damping characteristics further enhance the stability, thereby eliminating the shaking, surging and crawling phenomena. The direct drive motor 7 is embedded inside the motor base 4, and the motor base 4 is fixed inside the base 3 in the outer chamber of the air bearing core 9. The output end of the direct drive motor 7 is rigidly connected to the rotating spindle of the table 2. The direct drive motor 7 directly drives the table 2 to rotate around the fixed air bearing core 9 without intermediate transmission. At the same time, the grating ruler fixed on the outer circumference of the table 2 in the feedback grating system 5 forms a non-contact detection cooperation with the reading head installed on the reading head base 11. The angle and position signals of the table 2 rotation are collected in real time and used for the closed-loop control of the speed and position of the table 2, thereby controlling the radial runout, end face runout and positioning accuracy at the nanometer level. The electrical box 12 is fixedly installed on the outermost end face of the base 3 and is connected to the circuit of the direct drive motor 7 and the feedback grating system 5 to realize the electrical integration and external control of the whole machine. When the operation is completed, the direct drive motor 7 is turned off and the air source is cut off. The radial static pressure air film and the axial static pressure air film gradually dissipate, and the table 2 falls back smoothly.

[0035] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. An ultra-precision air static pressure turntable, comprising a base (3), characterized in that: The base (3) is an integral support base. An air bearing core (9) is rigidly fixed in the center of the base (3), and a platform (2) is sleeved on the outside of the air bearing core (9). The base (3) is equipped with a direct drive motor (7); the platform (2) is a rotating bearing body, the inner wall of the platform (2) is bonded with a radial brass bearing sleeve (1) by epoxy resin in the whole circumference, the lower end face of the platform (2) is rigidly connected to the axial thrust (6), and the rotating spindle of the platform (2) is rigidly connected to the output end of the direct drive motor (7). The air bearing core (9) has air passages (91) in the inner radial and axial directions. The radial brass bearing sleeve (1) and the outer circle of the air bearing core (9) form a radial air bearing fit pair. The axial thrust (6) and the axial end face of the air bearing core (9) form an axial air bearing fit pair. A throttle (10) is embedded in the air passage (91) of the air bearing core (9). A feedback grating system (5) is provided on the outer periphery of the axial thrust (6).

2. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The radial brass bearing sleeve (1) is made of refined brass. The mating surfaces of the radial brass bearing sleeve (1) and the air bearing core (9) are treated with ultra-precision grinding. The radial inner circular surface of the radial brass bearing sleeve (1) and the air bearing core (9) form a micron-level radial air film mating gap. The bonding area between the radial brass bearing sleeve (1) and the inner wall of the platform (2) forms an airtight and flat epoxy resin bonding layer.

3. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The table (2) is made of high-grade nitrided steel through ultra-precision machining. The top of the table (2) is a 300mm standard diameter bearing plate, and the plate is equipped with a workpiece clamping and positioning structure. The inner top surface of the table (2) is an axial main bearing air-bearing working surface, which is formed by integrated ultra-precision grinding of a high-precision vertical grinding machine.

4. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The base (3) is made of cast iron and is rigidly fixed to each component by fastening bolts inside the base (3).

5. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The base (3) is fixedly connected to a motor seat (4), which is located in the outer cavity of the air bearing core (9), and the direct drive motor (7) is installed in the motor seat (4).

6. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The axial thrust (6) is made of high-grade nitrided steel. The mating surface of the axial thrust (6) and the direct drive motor (7) is subjected to ultra-precision grinding. The axial thrust (6) is rigidly connected to the lower end face of the rotating spindle of the table (2). The axial thrust (6) and the axial thrust end face of the air bearing core (9) form a micron-level axial air film mating gap.

7. The ultra-precision air static pressure rotary table according to claim 6, characterized in that: An air distribution block (8) is installed at the outer air passage interface of the base (3). The air distribution block (8) is made of stainless steel precision machining. The air distribution block (8) integrates a filtration, pressure stabilization and flow distribution structure. The air passage (91) opened inside the air bearing core (9) is a radial and axial independent air passage. The air distribution block (8) is airtightly connected to the radial and axial independent air passage (91) inside the air bearing core (9).

8. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The feedback grating system (5) includes a grating ruler (51) and a reading head (52). The base (3) is provided with a reading head seat (11). The reading head seat (11) is made of high-rigidity structural steel and is precision machined. The reading head seat (11) is fixed to the side mounting position of the base (3) by fastening bolts. The grating ruler (51) is mounted on the outer circumference of the table (2). The reading head (52) is mounted on the reading head seat (11). The grating ruler (51) and the reading head (52) form a non-contact detection cooperation.

9. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: The air bearing core (9) is made of nitrided steel and is rigidly fixed to the center of the base (3) by fastening bolts. Throttling devices (10) are installed in the air bearing core (9) at the corresponding radial and axial positions. The throttle device (10) is connected to the radial and axial independent air passage (91) inside the air bearing core (9). The throttle device (10) adopts a high-precision small-hole throttling structure. The throttle device (10) is integrated and airtightly fixed through a sealing structure.

10. The ultra-precision air static pressure rotary table according to claim 1, characterized in that: An electrical box (12) is fixedly installed on the outermost end face of the base (3). The electrical box (12) integrates motor driver wiring, grating signal wiring, and pneumatic control wiring. The electrical box (12) is connected to the feedback grating system (5) and the direct drive motor (7) in a circuit.

Images