An aerostatic bearing with super low permeability porous-surface composite throttling

Abstract

The application discloses a kind of ultra-low permeability porous-surface composite throttling gas static pressure bearings, the gas static pressure bearing includes upper radial plate, porous throttling ring I, shaft sleeve, main shaft rotor, porous throttling ring II, porous throttling ring III and lower radial plate, the shaft sleeve is sleeved on main shaft rotor, is provided with annular step groove A on it so that it is formed with main shaft rotor between radial bearing of surface throttling form;The upper radial plate and lower radial plate are fixed in the upper and lower ends of main shaft rotor, are provided with annular step groove B on it so that it is formed with shaft sleeve between surface throttling form thrust bearing.Porous throttling ring is set in the gas supply groove of surface throttling form, to form porous-surface composite throttling gas static pressure bearing, to overcome the influence of porous throttling on surface throttling flow state, greatly improve the stiffness of bearing, and give full play to the excellent error homogenization effect of porous throttling and surface throttling, improve the rotary accuracy of bearing.

Description

Technical Field

[0001] This invention belongs to the field of ultra-precision machining equipment and relates to a gas static pressure bearing, specifically a gas static pressure bearing with ultra-low permeability porous material-surface composite throttling. Background Technology

[0002] With the in-depth development of modern aerospace, communication technology, military technology and many other fields, the precision requirements of key components are getting higher and higher. This also puts forward higher precision requirements for the processing equipment. As the core component of ultra-precision machine tools, the performance of ultra-precision spindles often directly determines the processing accuracy of ultra-precision machine tools.

[0003] Currently, a key application area for high-speed precision spindles is micro-machining of difficult-to-machine materials. During micro-machining, maintaining a high cutting speed requires the spindle to operate at a very high speed. On the other hand, the spindle also needs sufficient rigidity to ensure high rotational accuracy under alternating loads during the cutting process. To achieve high speed and precision machining accuracy in micro-machining spindles, mainstream international high-speed precision spindle systems generally rely on gas hydrostatic bearings for support.

[0004] Gas static pressure bearings have high rotational accuracy and exhibit minimal temperature change even at high speeds, resulting in very small thermal deformation errors. The key structural component determining the performance of a gas static pressure bearing is the throttling device. Currently, there are four main throttling methods for gas static pressure bearings: orifice throttling, slit throttling, surface throttling, and porous throttling. Orifice-type gas static pressure bearings have been used for a long time, and the related technologies and equipment are relatively mature. They have the advantages of being easy to design and having good performance. However, their low stiffness and high-frequency micro-vibrations caused by their own characteristics during operation hinder their further application. Slit-type bearings have good load-bearing capacity, but their overall performance is not as good as that of orifice-type gas static pressure bearings, so their application is not widespread. Surface-type bearings have a large load-bearing capacity and high stiffness matching, and are relatively simple to manufacture. However, due to their own structural characteristics, the gas flow state entering the throttling surface is unstable, resulting in a certain stiffness loss. With the continuous deepening of research, gas static pressure spindles designed with porous throttling methods have been proven to have better overall performance, and their load-bearing capacity and stiffness have significant advantages over other throttling forms.

[0005] In summary, each type of gas static bearing has its own advantages and disadvantages. Currently, the orifice type of gas static bearing has a large proportion of ultra-precision air bearing applications due to its low manufacturing cost and high cost-effectiveness. Although surface throttling and porous throttling types have better performance, their higher manufacturing cost limits their application to fields with high precision requirements. However, as people's requirements for machining accuracy and equipment performance continue to increase, even higher precision requirements are being placed on gas static bearings. Summary of the Invention

[0006] To improve the overall performance of gas static pressure bearings, this invention provides a gas static pressure bearing with ultra-low permeability porous material and surface composite throttling. In this invention, the porous throttling ring is made of ultra-low permeability porous material and is placed in the air supply groove in the form of surface throttling, thus forming a gas static pressure bearing with porous material and surface composite throttling. This overcomes the influence of porous material throttling on the surface throttling flow pattern, greatly improving the bearing stiffness. Furthermore, it fully utilizes the excellent error averaging effect of porous material throttling and surface throttling, improving the bearing's rotational accuracy. Simultaneously, the use of ultra-low permeability porous material and the surface throttling's non-generating air hammer characteristic ensure that the composite throttling does not produce air hammer vibration, greatly improving the bearing's stability.

[0007] The objective of this invention is achieved through the following technical solution:

[0008] A gas hydrostatic bearing with ultra-low permeability porous material-surface composite throttling technology includes an upper spoke plate, a porous throttling ring I, a bushing, a main shaft rotor, a porous throttling ring II, a porous throttling ring III, and a lower spoke plate, wherein:

[0009] The bushing is fitted onto the main shaft rotor;

[0010] The upper and lower spokes are fixed to the upper and lower ends of the main shaft rotor;

[0011] An annular stepped groove A is provided on the inner circular surface of the bushing, and a porous throttling ring II is provided in the annular stepped groove A, thereby cooperating with the main shaft rotor to form an annular air passage III and an annular air passage IV. The annular air passage IV, the bushing, and the gap formed between the bushing and the main shaft rotor together constitute a radial bearing in the form of surface throttling.

[0012] Both the upper and lower end faces of the bushing are provided with annular stepped grooves B. The upper and lower spokes are provided with annular grooves at corresponding positions of the annular stepped grooves B. A porous throttling ring I is provided in the annular stepped groove B on the upper end face of the bushing, thereby cooperating with the bushing and the upper spoke to form annular air passage I and annular air passage II. The gap formed between annular air passage I and the upper spoke and the bushing constitutes an upper thrust bearing in the form of surface throttling. A porous throttling ring III is provided in the annular stepped groove B on the lower end face of the bushing, thereby cooperating with the bushing and the lower spoke to form annular air passage V and annular air passage VI. The gap formed between annular air passage VI and the lower spoke and the bushing constitutes a lower thrust bearing in the form of surface throttling.

[0013] Compared with the prior art, the present invention has the following advantages:

[0014] 1. The present invention mainly adopts the structure of a gas static pressure bearing with surface throttling. The porous material is simply made by opening corresponding mounting grooves on the original structure of the gas static pressure bearing with surface throttling, which makes the processing and manufacturing relatively simple.

[0015] 2. After the gas is supplied to the bearing, it passes through the porous flow regulators located at each bearing before entering the surface throttling structure. This improves the gas flow pattern entering the surface throttling structure and greatly enhances the bearing stiffness.

[0016] 3. Since both porous throttling and surface throttling have excellent error averaging effects, stiffness and load-bearing capacity, coupling the two together gives the coupled bearing the combined advantages of the two original throttling forms. This results in the coupled air bearing having extremely high rotational accuracy and stiffness, as well as a large load-bearing capacity, which greatly improves its anti-interference ability.

[0017] 4. Due to the use of a permeability of 1×10 -18 Ultra-low permeability porous materials, compared to traditional materials with a permeability of 1×10 -14 ~1×10 -16 The porous material with ultra-low permeability has almost no flow under low pressure. Moreover, the combination of the ultra-low permeability porous material and the surface throttling characteristic that does not produce air hammer makes the composite throttling even less likely to produce air hammer vibration, which greatly improves the stability of the composite air bearing. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the air supply structure for the composite air bearing of the present invention;

[0019] Figure 2 This is a schematic diagram of the exhaust structure of the composite air-bearing of the present invention;

[0020] Figure 3This is a three-dimensional structural diagram of the composite air bearing of the present invention;

[0021] In the diagram, 1. Upper spoke plate, 2. Porous throttling ring I, 3. Bushing, 4. Main shaft rotor, 5. Porous throttling ring II, 6. Porous throttling ring III, 8. Connecting ring, 9. Lower spoke plate, 10. Base, 11. Base cover plate, 12. Reading head mounting seat, 13. Reading head, 14. Circular grating, 15. Grating mounting shaft, 16. Mover pressure plate, 17. Motor mover, 18. Motor stator, 19. Stator pressure plate, 20. Wiring harness box, 21. Data connector, 22. Chamber. Detailed Implementation

[0022] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0023] This invention provides a gas hydrostatic bearing with ultra-low permeability porous material-surface composite throttling, such as... Figure 1 and Figure 3 As shown, the gas hydrostatic bearing includes an upper spoke plate 1, a porous throttling ring I2, a bushing 3, a main shaft rotor 4, a porous throttling ring II5, a porous throttling ring III6, and a lower spoke plate 9, wherein:

[0024] The bushing 3 is fitted onto the main shaft rotor 4;

[0025] An annular stepped groove A is provided on the inner circular surface of the bushing 3. A porous throttling ring II5 is provided in the annular stepped groove A, thereby cooperating with the main shaft rotor 4 to form an annular air passage III and an annular air passage IV. The annular air passage IV, the bushing 3, and the gap formed between the bushing and the main shaft rotor 4 together constitute a radial bearing in the form of surface throttling.

[0026] The upper spoke 1 and the lower spoke 9 are fixed to the upper and lower ends of the main shaft rotor 4 by bolts;

[0027] The bushing 3 has annular stepped grooves B on both its upper and lower end faces. The upper spoke 1 and the lower spoke 9 each have annular grooves at corresponding positions in the annular stepped grooves B. A porous throttling ring I2 is disposed in the annular stepped groove B on the upper end face of the bushing 3, thereby cooperating with the bushing 3 and the upper spoke 1 to form annular air passage I and annular air passage II. The gap formed between annular air passage I and the upper spoke 1 and the bushing 3 constitutes an upper thrust bearing in the form of surface throttling. A porous throttling ring III6 is disposed in the annular stepped groove B on the lower end face of the bushing 3, thereby cooperating with the bushing 3 and the upper and lower spokes 9 to form annular air passage V and annular air passage VI. The gap formed between annular air passage VI and the lower spoke 9 and the bushing 3 constitutes a lower thrust bearing in the form of surface throttling.

[0028] In this invention, the porous throttling ring I2, porous throttling ring II5, and porous throttling ring III6 all use materials with a permeability of 1×10⁻⁶. -18 The ultra-low permeability porous material has a permeability of 1×10⁻⁶ compared to that used in traditional porous air bearings. -14 ~1×10 -16 Conventional porous materials with ultra-low permeability have almost no flow under low pressure, so high-pressure gas supply is required. Due to the use of high-pressure gas supply, the entire air bearing will have greater rigidity and load-bearing capacity. At the same time, due to the ultra-low permeability of porous materials and the characteristic of surface throttling that does not produce air hammer, the composite throttling air bearing will not produce air hammer vibration.

[0029] In this invention, the gas hydrostatic bearing further includes a connecting ring 8 and a base 10, wherein: the connecting ring 8 is fixed to the lower part of the bushing 3 by bolts; the base 10 is fixed to the lower part of the connecting ring 8 by bolts; the bushing 3 is provided with axially symmetrical radial air passage I, axial air passage I, and axial air passage II, the axial air passage I passing through the upper and lower end faces of the bushing 3, corresponding to and communicating with the annular air passage II and the annular air passage III, the radial air passage I corresponding one-to-one with the axial air passage I and communicating with each other, and the radial air passage I corresponding to and communicating with the annular air passage III; the connecting ring 8 is provided with two axial air passages symmetrically arranged along the upper and lower end faces of the connecting ring 8. The axial air passage III corresponds one-to-one with the axial air passage II and is interconnected with each other. The base 10 is symmetrically arranged with two axial air passages IV and an air supply hole. The axial air passages IV and III correspond one-to-one and are interconnected with each other, and the air supply hole corresponds one-to-one with the axial air passages IV and is interconnected with each other. The annular air passages II, III and V are used to supply air to the porous throttling ring I2, the porous throttling ring II5 and the porous throttling ring III6 respectively. The above forms two air supply paths for the porous-surface composite throttling gas static pressure bearing that are symmetrical along the axis. One of them can be used as a backup air supply path.

[0030] In this invention, the gas static pressure bearing further includes a mover plate 16, a motor mover 17, a motor stator 18, and a stator plate 19, wherein: the lower part of the lower spoke 9 is a stepped cylindrical structure, the motor mover 17 is disposed on it, and is fixed to the bottom of the lower spoke 9 by bolts connecting the mover plate 16 and the lower spoke 9; the base 10 is provided with an annular groove, the motor stator 18 is disposed in the annular groove, and is fixed in the annular groove by bolts connecting the stator plate 19 and the base 10; the motor mover 17 and the motor stator 18 are rotatably connected; the rotation center line of the motor mover 17 is consistent with the rotation center line of the main shaft rotor 4.

[0031] In this invention, the motor mover 17 and the motor stator 18 are frameless torque motors.

[0032] In this invention, such as Figure 2 As shown, the bushing 3 is also symmetrically provided with oblique air passage I, oblique air passage II, and axial air passage V along its axis. Specifically: chamfer structures A are provided on both the upper and lower sides of the inner circular surface of the bushing 3, and chamfer structures B are also provided on both the upper and lower sides of the main shaft rotor 4. An annular groove is provided on the upper spoke 1 and lower spoke 9 corresponding to the positions of chamfer structures A and B. The chamfer structures A, B, and annular grooves together form annular air passages VII and VIII. Oblique air passage I corresponds to and is interconnected with annular air passage VII, and oblique air passage II corresponds to and is interconnected with annular air passage VIII. Oblique air passages I and II are each paired with an axial air passage V. They should be interconnected; the connecting ring 8 is symmetrically provided with two axial air passages VI that pass through the upper and lower end faces of the connecting ring 8; the axial air passages VI and axial air passages V correspond one-to-one and are interconnected; the gas discharged from the air film gap of each bearing surface passes through the above-mentioned oblique air passage I, oblique air passage II, axial air passage V, annular air passage VII, annular air passage VIII and axial air passage VI, passes through the gap between the lower spoke 9 and the base 10, and then flows into the chamber 22 at the lower part of the bearing through the gap between the motor mover 17 and the motor stator 18. The base 10 is provided with an exhaust hole that communicates with the chamber 22, thereby discharging the gas. The above constitutes the exhaust air passage.

[0033] In this invention, the gas static pressure bearing further includes a base cover plate 11, a reading head mounting seat 12, a reading head 13, a circular grating 14, and a grating mounting shaft 15, wherein: the base cover plate 11 is fixed to the base 10 by bolts to seal the base 10; the reading head 13 is fixed to the base 10 by the reading head mounting seat 12 and bolts; the grating mounting shaft 15 is fixed to the lower part of the lower spoke 9 by bolts; the circular grating 14 is fixed to the grating mounting shaft 15 by bolts; the rotation axis of the circular grating 14 is consistent with the rotation center line of the main shaft rotor 4; the circular grating 14 and the reading head 13 are used for position feedback of the gas static pressure turntable.

[0034] In this invention, the gas static pressure bearing further includes a wire harness box 20 and a data connector 21, wherein: the wire harness box 20 is installed on the side wall of the base 10 for fixing the data connector 21; the data connector 21 is installed on the wire harness box 20 for connecting the wire harness on the motor stator 18 and the reading head 13.

[0035] In this invention, since the main structure adopted is a surface-throttling gas static pressure bearing, the porous material is simply made by opening corresponding mounting grooves on the original surface-throttling gas static pressure bearing structure, which is relatively simple to process and manufacture, and can make full use of existing processing equipment.

[0036] In this invention, after the gas is supplied to the entire composite air bearing, the gas passes through a porous throttling device located at each bearing before entering the surface throttling structure. This improves the gas flow pattern entering the surface throttling structure and greatly enhances the bearing stiffness.

[0037] In this invention, since both porous throttling and surface throttling have excellent error averaging effects, stiffness and load-bearing capacity, coupling the two together allows the coupled bearing to have the combined advantages of the original two throttling forms. As a result, the coupled air bearing has extremely high rotational accuracy and stiffness, as well as a large load-bearing capacity, which greatly improves its anti-interference ability.

[0038] In this invention, the figure shows a structural diagram of a gas static pressure turntable using a gas static pressure bearing with ultra-low permeability porous material-surface composite throttling. However, this invention is not limited to the structural form of the turntable and can also be applied to a gas static pressure spindle.

Claims

1. A gas hydrostatic bearing with ultra-low permeability porous material-surface composite throttling, characterized in that... The gas static pressure bearing includes an upper spoke plate, a porous throttling ring I, a bushing, a main shaft rotor, a porous throttling ring II, a porous throttling ring III, and a lower spoke plate, wherein: The bushing is fitted onto the main shaft rotor; The upper and lower spokes are fixed to the upper and lower ends of the main shaft rotor; An annular stepped groove A is provided on the inner circular surface of the bushing, and a porous throttling ring II is provided in the annular stepped groove A, thereby cooperating with the main shaft rotor to form an annular air passage III and an annular air passage IV. The annular air passage IV, the bushing, and the gap formed between the bushing and the main shaft rotor together constitute a radial bearing in the form of surface throttling. The bushing has an annular stepped groove B on both the upper and lower end faces. The upper and lower spokes have annular grooves at corresponding positions on the annular stepped groove B. The porous throttling ring I is set in the annular stepped groove B on the upper end face of the bushing, thus forming annular air passage I and annular air passage II with the bushing and the upper spoke. The gap formed between the annular air passage I, the upper spoke, and the bushing constitutes an upper thrust bearing in the form of surface throttling. The porous throttling ring III is set in the annular stepped groove B on the lower end face of the bushing, thus forming annular air passage V and annular air passage VI with the bushing and the lower spoke. The gap formed between the annular air passage VI, the lower spoke, and the bushing constitutes a lower thrust bearing in the form of surface throttling. The porous throttling ring I, porous throttling ring II, and porous throttling ring III all use materials with a permeability of 1×10⁻⁶. -18 Ultra-low permeability porous materials.

2. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 1, characterized in that... The gas hydrostatic bearing further includes a connecting ring and a base, wherein: The connecting ring is fixed to the lower part of the bushing; The base is fixed to the lower part of the connecting ring; The bushing is provided with an axisymmetric radial air passage I, axial air passage I and axial air passage II. Axial air passage I passes through the upper and lower end faces of the bushing and corresponds to and is connected to annular air passage II and annular air passage V. Radial air passage I corresponds to and is connected to axial air passage I. Radial air passage I corresponds to and is connected to annular air passage III. The connecting ring is provided with two axial air passages III that pass through the upper and lower end faces of the connecting ring along the axis symmetrically. The axial air passages III and axial air passages II correspond one-to-one and are interconnected with each other. The base is symmetrically provided with two axial air passages IV and an air supply hole. The axial air passages IV and III correspond one-to-one and are interconnected. The air supply hole corresponds one-to-one with the axial air passages IV and is interconnected. The annular air passages II, III, and V are used to supply air to the porous throttling rings I, II, and III, respectively.

3. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 2, characterized in that... The gas hydrostatic bearing further includes a mover pressure plate, a motor mover, a motor stator, and a stator pressure plate, wherein: The lower part of the lower spoke plate is a stepped cylindrical structure; The motor actuator is fixed to the bottom of the lower spoke plate by an actuator pressure plate; The base is provided with an annular groove, and the motor stator is fixed in the annular groove by a stator pressure plate; The motor mover and the motor stator are rotatably connected.

4. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 3, characterized in that... The rotation center line of the motor mover is consistent with the rotation center line of the main shaft rotor.

5. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 3, characterized in that... The motor mover and motor stator are frameless torque motors.

6. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 3, characterized in that... The bushing is also provided with an oblique airway I, an oblique airway II, and an axial airway V symmetrically along the axis, wherein: The inner circular surface of the bushing is provided with chamfered structure A on both the upper and lower sides, and the main shaft rotor is provided with chamfered structure B on both the upper and lower sides. The upper and lower spokes are provided with an annular groove corresponding to the positions of chamfered structure A and chamfered structure B. The chamfered structure A, chamfered structure B and annular groove together form annular air passage VII and annular air passage VIII. The oblique airway I corresponds to and is connected to the annular airway VII, the oblique airway II corresponds to and is connected to the annular airway VIII, and both the oblique airway I and the oblique airway II correspond one-to-one with the axial airway V and are connected to each other. The connecting ring is symmetrically provided with two axial air passages VI that pass through the upper and lower end faces of the connecting ring. The axial air passages VI and V correspond one-to-one and are interconnected. The gas discharged from the air film gaps of each bearing surface passes through the aforementioned oblique air passage I, oblique air passage II, axial air passage V, annular air passage VII, annular air passage VIII and axial air passage VI, then through the gap between the lower spoke and the base, and then through the gap between the motor mover and the motor stator before flowing into the chamber at the bottom of the bearing. The base is provided with an exhaust hole that communicates with the chamber, thereby discharging the gas.

7. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 6, characterized in that... The gas static pressure bearing also includes a base cover plate, a reading head mounting seat, a reading head, a circular grating, and a grating mounting shaft, wherein: The base cover plate is fixed to the base and is used to seal the base; The reading head is fixed to the base by a reading head mounting bracket; The grating mounting shaft is fixed to the lower part of the lower spoke plate; The circular grating is fixed on the grating mounting shaft.

8. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 7, characterized in that... The rotation axis of the circular grating is aligned with the rotation center line of the main shaft rotor 4.

9. The ultra-low permeability porous material-surface composite throttling gas hydrostatic bearing according to claim 7, characterized in that... The gas hydrostatic bearing also includes a wiring harness box and a data connector, wherein: The wire harness box is mounted on the side wall of the base for fixing the data connector; The data connector is installed on the wiring harness box and is used to connect the wiring harness of the motor stator and the reading head.

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