Composite throttling static pressure gas thrust bearing for air floating main shaft of wafer thinning machine

Abstract

The invention discloses a composite throttling static pressure gas thrust bearing for a wafer thinning machine gas floating main shaft, and belongs to the technical field of static pressure gas bearings. Comprising a bearing base, a bearing shell, a bearing end cover and a composite flow controller which are sequentially connected in the axial direction, and a pre-tightening pressing ring, elastic rings and a vibration ring used for transmitting vibration motion of the bearing end cover which are arranged between the bearing base and the interior of the bearing shell in the axial direction, and the two ends of the vibration ring in the axial direction are each provided with one elastic ring; coaxial annular cylinder cavities are formed in the corresponding connecting faces of the bearing base and the bearing shell respectively, the pre-tightening pressing ring and the elastic ring are of two annular structures with the same inner diameter and the same outer diameter, and piezoelectric patches are pasted to the two axial end faces of the elastic ring respectively. According to the device, the axial vibration motion of the bearing end cover is transmitted to the elastic ring through the vibration ring, piezoelectric shunt damping is provided for the bearing through the piezoelectric patches on the elastic ring, the vibration amplitude of the bearing end cover is reduced, and the stability of the static pressure gas thrust bearing is effectively improved.

Description

Technical Field

[0001] This invention relates to a composite throttling static pressure gas thrust bearing, specifically a composite throttling static pressure gas thrust bearing for the air-bearing spindle of a wafer thinning machine, belonging to the technical field of static pressure gas bearings. Background Technology

[0002] 3D packaging technology based on through-silicon vias (TSVs) enables the assembly of multiple chips or wafers through short vertical interconnects, achieving chip miniaturization, ultra-short and ultra-high bandwidth interconnects, and ultra-high reliability. For the processed wafer, excessively thick substrate material on the back side reduces chip heat dissipation efficiency and limits the number of chips that can be packaged in the same space, hindering improvements in chip integration and performance. Therefore, wafer backside thinning technology is needed to reduce the thickness of each chip layer. The wafer grinding spindle, as the "heart" of the wafer thinning machine, is a major factor limiting the performance of 3D chip packaging. The high hardness and brittleness of third-generation semiconductor materials such as SiC require the grinding spindle to have high rotational accuracy, high load-bearing capacity, high rigidity, and good stability.

[0003] Because hydrostatic bearings experience high temperature rise at high speeds, additional cooling devices increase the complexity of grinding spindles and wafer thinning machine structures. Therefore, air hydrostatic spindles, with their high precision and low temperature rise, are the ideal choice for wafer thinning machines. As supporting components of the air hydrostatic spindle, the performance of the hydrostatic thrust bearing and radial bearing determines the spindle's machining performance. Throttling types for hydrostatic bearings mainly include porous material throttling, orifice throttling, and slit throttling. Compared to other throttling methods, porous materials, relying on their intricate internal pore structure, change the bearing's gas supply from a point source to a surface source, resulting in a more uniform gas film pressure distribution within the bearing clearance. This leads to greater bearing capacity, stiffness, and improved stability. However, due to the inherent properties of gas—compressibility and low viscosity—vibration in air hydrostatic bearings is unavoidable. As the intensity of eddy currents within the bearing's gas film increases, the vibration energy intensifies. When the eddy current frequency approaches the bearing's natural frequency, the vibration transforms from micro-vibration to air hammer vibration, leading to air hydrostatic spindle system failure.

[0004] To improve the stability of hydrostatic gas bearings, external dampers such as squeeze film dampers and metal mesh dampers are added to absorb some vibration energy, reduce the vibration amplitude of the bearing, and improve its stability. For example, in patent application CN119532324A, entitled "A Porous Gas Thrust Bearing with Elastic Ring Squeeze Film Dampers," an elastic ring, a pressure equalizing ring, an oil seal, and a sector-shaped transmission element are sequentially installed in the bearing base. The bearing cover is connected to the end face of the bearing base. The T-shaped connecting plate of the sector-shaped transmission element is connected to the T-shaped groove on the back of the tilting pad, transmitting the axial movement of the tilting pad to the pressure equalizing ring. The pressure equalizing ring squeezes two elastic ring squeeze film dampers installed in the bearing base. The elastic ring undergoes axial elastic deformation to provide elastic support for the tilting pad, while the damping fluid in the oil film is squeezed and flows through the oil passage, generating viscous damping and improving the bearing's operational stability.

[0005] However, the following problems still exist in hydrostatic gas bearings that currently use elastic ring extrusion oil film dampers: 1) The elastic ring extrusion oil film damper dissipates vibration energy by using viscous damping fluid to reciprocate in the oil passage. After long-term service or in high-temperature environments, the viscosity of the damping fluid in the damper decreases, which in turn leads to the attenuation of the damping capacity of the elastic ring extrusion oil film damper. 2) Although two elastic ring-type extrusion oil film dampers are installed in the bearing base to work together to increase the damping performance, the two elastic ring-type extrusion oil film dampers are located on the same side of the axial direction of the sector-shaped transmission element. When the excitation load decreases from large to small, the elastic restoring force of the elastic ring will cause the sector-shaped transmission element to impact the bearing cover, which will have an adverse effect on the stability of the bearing. 3) The elastic ring extrusion oil film damper has a strong frequency dependence. When the excitation frequency is constant, the damper has relatively stable stiffness and damping characteristics. However, as the excitation frequency gradually increases, the stiffness of the damper increases and the damping decreases. The elastic ring extrusion oil film damper will lose most of its damping capacity under high frequency excitation, and the bearing stability will decrease accordingly. 4) The sealing elements in the elastic ring extrusion film damper are subject to wear and oxidation, which poses a risk of leakage of the damping fluid in the extrusion film damper. This limits the application of hydrostatic gas bearings using extrusion film dampers in fields such as semiconductor processing, medical treatment, and ultra-precision measurement.

[0006] Therefore, there is an urgent need to design a hydrostatic gas thrust bearing with an oil-free damper, so that it can maintain efficient damping performance at high excitation frequencies and adapt to extreme working conditions, thereby broadening the application scenarios of hydrostatic gas bearings. Summary of the Invention

[0007] The purpose of this invention is to solve the problems of poor bearing stability and damping characteristics in the prior art, and to provide a composite throttling static pressure gas thrust bearing for the air-bearing spindle of a wafer thinning machine. By designing a vibration ring structure between two elastic rings, the axial vibration motion of the bearing end cover is transmitted to the elastic rings, and the piezoelectric sheet on the elastic ring provides piezoelectric shunt damping for the bearing, thereby reducing the vibration amplitude of the bearing end cover and effectively improving the stability of the static pressure gas thrust bearing.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a composite throttling static pressure gas thrust bearing for the air-floating spindle of a wafer thinning machine, comprising a bearing base, a bearing housing, a bearing end cover and a composite throttling device connected sequentially along the axial direction, and a pre-tightening ring, an elastic ring and a vibration ring for transmitting the vibration motion of the bearing end cover disposed axially between the bearing base and the bearing housing, wherein an elastic ring is provided at each of the two ends of the vibration ring along the axial direction; The bearing base and bearing housing are respectively provided with coaxial annular cylindrical cavities on their corresponding connecting surfaces. The bearing base and bearing housing are respectively provided with a center hole of the base and a center hole of the housing with the same diameter and axially penetrating. The cylinder between the center hole of the base and the center hole of the housing and its outer circumference is respectively provided with a damper mounting groove and an elastic ring mounting groove with the same inner and outer diameter. Multiple base sector grooves and housing sector grooves are respectively provided on the end face of the cylinder between the damper mounting groove and the center hole of the base, and between the elastic ring mounting groove and the center hole of the housing. The pre-tightening ring and the elastic ring are two ring-shaped structures with the same inner and outer diameters. The elastic ring has inner and outer bosses evenly spaced along the circumferential direction on both axial end faces, and the inner and outer bosses are staggered in the circumferential direction. Piezoelectric sheets are attached to the end faces of the elastic ring between two adjacent inner bosses and two adjacent outer bosses, and the axial height of the piezoelectric sheets after attachment is lower than the thickness of the inner or outer boss. The pre-tightening ring and the elastic ring are sequentially connected in the damper mounting groove. The two end faces of the pre-tightening ring are in contact with the bottom surface of the damper mounting groove and the inner boss of the elastic ring, respectively. The elastic ring is connected in the elastic ring mounting groove, and the inner boss of the elastic ring is in contact with the bottom surface of the elastic ring mounting groove. The vibration ring is composed of a coaxial annular pressure block and an annular mandrel connected by multiple fan-shaped connecting plates evenly distributed along the circumference. The upper and lower ends of the annular pressure block are respectively fitted into the fan-shaped groove of the base and the fan-shaped groove of the shell. The two axial end faces of the annular pressure block are respectively in contact with the outer protrusions of two elastic rings located in the damper mounting groove and the elastic ring mounting groove. The inner and outer circumferential walls of the annular pressure block are fitted and connected to the inner and outer circumferential walls of the damper mounting groove and the elastic ring mounting groove. The fan-shaped connecting plates are simultaneously embedded and connected in the fan-shaped groove of the base and the fan-shaped groove of the shell. The circumferential sidewalls of the fan-shaped connecting plates are in close contact with the groove walls of the fan-shaped groove of the base and the fan-shaped groove of the shell. The lower end face of the bearing end cover is provided with a stepped shaft, and the middle part of the annular mandrel is provided with a mandrel hole. The upper small diameter shaft of the stepped shaft is interference-fitted in the mandrel hole, and the end face of the upper large diameter shaft is in contact with the upper end face of the annular mandrel. The upper end face of the bearing end cover is provided with a pressure equalization cavity. Multiple fan-shaped pressure equalization blocks are evenly distributed in the circumferential direction on the pressure equalization cavity in two concentric circles. The circumferential spacing between the fan-shaped pressure equalization blocks forms the pressure equalization groove of the pressure equalization cavity. The center of the stepped shaft is also provided with an air intake channel that passes through the bottom end face of the stepped shaft and the pressure equalization cavity. A composite throttle is attached to the upper axial end face of the fan-shaped pressure equalizing block, and the outer circumferential side wall of the composite throttle is sealed to the bearing end cover; multiple air chambers are evenly distributed along the circumferential direction on the lower axial end face of the composite throttle, and multiple shallow static pressure chambers are set on the lower axial end face corresponding to the positions of the air chambers. The air chambers and the shallow static pressure chambers are connected through throttle holes, and the circumferential position of the air chambers corresponds to the pressure equalizing grooves formed between the multiple fan-shaped pressure equalizing blocks located on the outer ring.

[0009] The elastic ring, the pre-tightening ring, and the bearing housing are all provided with circumferential fixing structures. Two anti-rotation plungers are symmetrically arranged along the circumferential direction on the elastic ring located between the two piezoelectric plates. The upper axial end face of the pre-tightening ring and the bottom surface of the elastic ring mounting groove are respectively provided with damper anti-rotation grooves and elastic ring anti-rotation grooves corresponding to the anti-rotation plungers. The elastic ring, the pre-tightening ring, and the bearing housing are circumferentially fixed by the cooperation of the anti-rotation plungers with the damper anti-rotation grooves and the elastic ring anti-rotation grooves, respectively.

[0010] A circumferential fixing structure is provided between the preload ring and the bearing base. Multiple positioning plungers are provided along the circumferential direction on the axial lower end face of the preload ring. A preload ring anti-rotation groove is provided on the bottom surface of the damper mounting groove corresponding to the positioning plungers. The preload ring and the bearing base are circumferentially fixed by the cooperation of the positioning plungers and the preload ring anti-rotation groove. A preload threaded hole penetrating the bottom surface of the bearing base and the damper mounting groove is also provided in the preload ring anti-rotation groove.

[0011] The elastic ring has a thickness of 0.8~1.2mm, the inner boss and the outer boss both have a thickness of 0.8~1.0mm, a circumferential angle of 12°~18°, and the interval angle between two adjacent inner bosses or outer bosses is 28°~32°; the piezoelectric sheet has a length of 8~12mm, a width of 6~8mm, and an axial thickness of 0.3~0.5mm.

[0012] The bearing base has a radially arranged base wiring hole that communicates with the damper mounting groove on its outer cylindrical surface, and the bearing housing has a radially arranged housing wiring hole that communicates with the elastic ring mounting groove on its outer cylindrical surface. The leads of the piezoelectric sheet on the elastic ring pass through the base wiring hole and the housing wiring hole respectively and are connected to the piezoelectric shunt circuit. The resistors and inductors in the piezoelectric shunt circuit are connected in series or in parallel.

[0013] The circumferential angle of the base sector groove and the circumferential angle of the shell sector groove are both 45° and the groove depth is 3mm; the circumferential angle of the sector connecting plate is 45° and the axial thickness is 4mm.

[0014] The sector-shaped pressure equalizing blocks located in the inner ring consist of a first group of three sector-shaped pressure equalizing blocks with a circumferential angle of 120°, and the sector-shaped pressure equalizing blocks located in the outer ring consist of a second group of six sector-shaped pressure equalizing blocks with a circumferential angle of 60°. The two groups of sector-shaped pressure equalizing blocks together form the support structure of the composite throttling device.

[0015] The composite throttle has an axial thickness of 4-6 mm, a gas chamber diameter of 1.8-2.0 mm, a static pressure shallow chamber diameter of 1.8-2.0 mm and an axial depth of 0.1-0.2 mm; and a throttle orifice diameter of 0.15-0.30 mm and an axial length of 0.8-1.0 mm.

[0016] Multiple threaded holes are evenly distributed along the circumference on the connecting end face between the bearing base and the bearing housing, and are fixed together by bolts; multiple threaded holes are evenly distributed along the circumference on the upper end face between the upper large diameter shaft of the stepped shaft and the annular mandrel; the bearing end cover and the vibration ring are fixedly connected together by the engagement of threaded holes and bolts.

[0017] The beneficial effects of this invention are: 1) The device of the present invention designs a vibration ring structure between two elastic rings and uses an annular mandrel and a fan-shaped connecting plate structure to transmit the axial vibration motion of the bearing end cover to the annular pressure block. When the bearing end cover is disturbed by the gas film eddy current and vibrates axially, the annular pressure block squeezes the elastic rings at both ends of its axial direction, causing the elastic rings to undergo elastic deformation. The elastic rings undergo elastic deformation to resist the axial load. At the same time, the piezoelectric sheet attached to the elastic ring converts the strain energy of the elastic ring into electrical energy. The piezoelectric shunt circuit connected to the piezoelectric sheet consumes the electrical energy generated by the piezoelectric sheet, providing piezoelectric shunt damping for the rotor-bearing system, reducing the vibration amplitude of the bearing end cover, and effectively improving the stability of the hydrostatic gas thrust bearing.

[0018] 2) In the device of the present invention, two elastic rings are respectively set at both ends of the annular pressure block. By adjusting the pre-tightening screw at the bottom of the bearing base, the pre-tightening pressure ring is pushed to squeeze the elastic ring along the axis, which can eliminate the installation gap between the two elastic rings and the annular pressure block and realize the adjustment of the pre-tightening amount of the elastic rings. When the annular pressure block vibrates axially, the vibrating ring and the elastic rings at both ends of its axis always remain in close contact, and no impact load is generated, which is beneficial to the improvement of bearing stability.

[0019] 3) In this invention, piezoelectric sheets are attached to the groove areas of the elastic rings between the elastic ring bosses, which can make full use of the strain energy generated when the elastic rings deform; the two elastic rings simultaneously absorb the vibration mechanical energy of the vibrating ring, which further improves the damping effect of the composite throttling static pressure gas thrust bearing of this invention; while the elastic rings generate elastic deformation to transfer strain energy to the piezoelectric sheets, their own elastic deformation can effectively resist the axial load of the bearing, and the bearing does not need to be equipped with additional elastic support elements, reducing the number of bearing parts.

[0020] 4) This invention combines a piezoelectric sheet with an elastic ring to provide piezoelectric shunt damping for a composite throttling hydrostatic gas thrust bearing. Compared with traditional extrusion oil film dampers, the piezoelectric shunt damping can maintain good damping capacity as the excitation frequency increases, and the piezoelectric shunt damping is not sensitive to changes in ambient temperature. This makes the composite throttling hydrostatic gas thrust bearing of this invention have excellent damping performance in high excitation frequency or extreme temperature environments.

[0021] 5) The composite throttling device in this invention has a set of perforated throttling devices on a porous throttling device substrate. After part of the lubricating gas is throttled through the throttling holes, a high-pressure bearing gas film is formed in the shallow static pressure cavity. The remaining pressurized gas permeates into the porous throttling device and forms a lubricating gas film around the shallow static pressure cavity after being throttled through the porous material. This creates a sealing effect on the high-pressure bearing gas film at the throttling holes, effectively reducing the gas film pressure loss in the bearing clearance and improving the bearing capacity and stiffness of the composite throttling static pressure gas shaft. Attached Figure Description

[0022] Figure 1 This is an exploded view of the composite throttling thrust bearing of the present invention; Figure 2 These are the front view and left view of the composite throttling thrust bearing of the present invention; Figure 3 for Figure 2 Rotational cross-sectional view of a composite throttling thrust bearing; Figure 4 This is a cross-sectional view of the composite throttling thrust bearing of the present invention; Figure 5 for Figure 1 A three-dimensional structural diagram of the bearing base; Figure 6 for Figure 1 A three-dimensional structural diagram of the bearing housing; Figure 7 for Figure 1 A three-dimensional structural diagram of the pre-tightening ring; Figure 8 for Figure 1 Front view, left view, and rear view of the elastic ring; Figure 9 for Figure 1A three-dimensional structural schematic diagram and cross-sectional view of the vibration ring; Figure 10 for Figure 1 A three-dimensional structural diagram of the bearing end cap; Figure 11 for Figure 1 Cross-sectional view and partial enlarged view of the composite throttle device; Figure 12 This is a schematic diagram illustrating the working principle of the composite throttle in this invention; Figure 13 This is a schematic diagram of the piezoelectric shunt circuit of the piezoelectric element in this invention.

[0023] In the diagram, 1-bearing base, 101-damper mounting groove, 102-preload ring anti-rotation groove, 103-base cable routing hole, 104-base sector groove, 105-base center hole, 2-bearing housing, 201-elastic ring mounting groove, 202-elastic ring anti-rotation groove, 203-housing cable routing hole, 204-housing sector groove, 205-housing center hole, 3-preload ring, 301-damper anti-rotation groove, 302-positioning plunger, 4-spring 401-Inner boss, 402-Outer boss, 403-Anti-rotation plunger, 404-Piezoelectric plate, 5-Vibration ring, 501-Annular pressure block, 502-Fan-shaped connecting plate, 503-Annular mandrel, 504-Mandrel hole, 6-Bearing end cap, 601-Pressure equalizing chamber, 602-Fan-shaped pressure equalizing block, 603-Stepped shaft, 604-Intake channel, 7-Compound throttle, 701-Air chamber, 702-Throttle orifice, 703-Shallow static pressure chamber. Detailed Implementation

[0024] The present invention will be further explained and described below with reference to the accompanying drawings and specific embodiments.

[0025] Example: Figures 1-4 As shown, the present invention provides a composite throttling static pressure gas thrust bearing for the air-bearing spindle of a wafer thinning machine, comprising a bearing base 1, a bearing housing 2, a bearing end cover 6, and a composite throttling device 7 connected sequentially along the axial direction, and a pre-tightening ring 3, an elastic ring 4, and a vibration ring 5 for transmitting the vibrational motion of the bearing end cover 6 installed axially between the bearing base 1 and the bearing housing 2, wherein an elastic ring 4 is provided at each of the two ends of the vibration ring 5 along the axial direction; the bearing end cover 6 and the vibration ring 5 are connected by a bolt group to transmit the vibrational motion of the bearing end cover 6 to the vibration ring 5.

[0026] like Figure 5 and Figure 6As shown, coaxial annular cylindrical cavities are respectively provided on the corresponding connecting surfaces of the bearing base 1 and the bearing housing 2. The bearing base 1 and the bearing housing 2 are respectively provided with a coaxial diameter and an axially penetrating center hole 105 and a housing center hole 205. The cylinders between the center hole 105 and the housing center hole 205 and their outer circumferences are respectively provided with damper mounting grooves 101 and elastic ring mounting grooves 201 with the same inner and outer diameters. The cylinder end faces between the damper mounting groove 101 and the center hole 105 of the base, and between the elastic ring mounting groove 201 and the center hole 205 of the housing are respectively provided with four base sector grooves 104 and housing sector grooves 204 evenly distributed along the circumferential direction. The circumferential angle of the base sector groove 104 and the housing sector groove 204 is 45° and the groove depth is 3mm.

[0027] The bearing base 1 has a base cable hole 103 that communicates with the damper mounting groove 101 on the outer cylindrical surface of the bearing base 1 in the radial direction. The bearing housing 2 has a housing cable hole 203 that communicates with the elastic ring mounting groove 202 on the outer cylindrical surface of the bearing housing 2 in the radial direction. Multiple threaded holes are evenly distributed along the circumferential direction on the connecting end faces between the bearing base 1 and the bearing housing 2, and they are fixed together by bolts.

[0028] like Figure 7 As shown, the upper axial end face of the pre-tightening ring 3 is provided with a damper anti-rotation groove 301, and the lower axial end face of the pre-tightening ring 3 is provided with a positioning plunger 302.

[0029] like Figure 8 As shown, the pre-tightening ring 3 and the elastic ring 4 are two ring structures with the same inner and outer diameters. The inner boss 401 and the outer boss 402 are evenly spaced along the circumferential direction on the two axial end faces of the elastic ring 4, and the inner boss 401 and the outer boss 402 are staggered in the circumferential direction. Piezoelectric sheets 404 are attached to the end faces of the elastic ring 4 between two adjacent inner bosses 401 and two adjacent outer bosses 402, and the axial height of the piezoelectric sheet 404 after attachment is lower than the thickness of the inner boss 401 or the outer boss 402.

[0030] The thickness of the elastic ring 4 is 0.8~1.2mm. To ensure that the elastic ring 4 produces uniform elastic deformation, the circumferential angle of the boss should be smaller than the interval angle between two adjacent inner bosses 401 or two adjacent outer bosses 402. The thickness of the inner bosses 401 and the outer bosses 402 is 0.8~1.0mm, the circumferential angle is 12°~18°, and the interval angle between two adjacent inner bosses 401 or outer bosses 402 is 28°~32°. The piezoelectric sheet 404 has a length of 8~12mm, a width of 6~8mm, and an axial thickness of 0.3~0.5mm.

[0031] A pre-tightening ring 3 and an elastic ring 4 are sequentially connected in the damper mounting groove 101. The two end faces of the pre-tightening ring 3 are in contact with the bottom surface of the damper mounting groove 101 and the inner boss 401 of the elastic ring 4, respectively. An elastic ring 4 is connected in the elastic ring mounting groove 201. The inner boss 401 of the elastic ring 4 is in contact with the bottom surface of the elastic ring mounting groove 201.

[0032] A circumferential fixing structure is provided between the elastic ring 4, the pre-tightening ring 3, and the bearing housing 2. Two anti-rotation plungers 403 are symmetrically arranged along the circumferential direction on the elastic ring 4 located between the two piezoelectric plates 404. The upper axial end face of the pre-tightening ring 3 and the bottom surface of the elastic ring mounting groove 201 are respectively provided with damper anti-rotation groove 301 and elastic ring anti-rotation groove 202 corresponding to the anti-rotation plungers 403. The elastic ring 4, the pre-tightening ring 3, and the bearing housing 2 are circumferentially fixed by the cooperation of the anti-rotation plungers 403 with the damper anti-rotation groove 301 and the elastic ring anti-rotation groove 202.

[0033] A circumferential fixing structure is provided between the preload ring 3 and the bearing base 1. Multiple positioning plungers 302 are provided along the circumferential direction on the axial lower end face of the preload ring 3. A preload ring anti-rotation groove 102 is provided on the bottom surface of the damper mounting groove 101 corresponding to the positioning plungers 302. The preload ring 3 and the bearing base 1 are circumferentially fixed by the cooperation between the positioning plungers 302 and the preload ring anti-rotation groove 102. A preload threaded hole penetrating the bottom surface of the bearing base 1 and the damper mounting groove 101 is also provided in the preload ring anti-rotation groove 102.

[0034] like Figure 3 and Figure 9 As shown, the vibration ring 5 is composed of a coaxial annular pressure block 501 and an annular spindle 503 connected by four evenly distributed sector-shaped connecting plates 502 along the circumferential direction. The upper and lower ends of the annular pressure block 501 are respectively connected to the sector-shaped groove 104 of the base and the sector-shaped groove 204 of the shell. The two axial end faces of the annular pressure block 501 are respectively in contact with the outer protrusions 402 of the two elastic rings 4 located in the damper mounting groove 101 and the elastic ring mounting groove 201. The inner and outer circumferential walls of the annular pressure block 501 are in close contact with the inner and outer circumferential walls of the damper mounting groove 101 and the elastic ring mounting groove 201. The sector-shaped connecting plates 502 are simultaneously embedded in the sector-shaped groove 104 of the base and the sector-shaped groove 204 of the shell. The circumferential sidewalls of the sector-shaped connecting plates 502 are in close contact with the groove walls of the sector-shaped groove 104 of the base and the sector-shaped groove 204 of the shell.

[0035] The vibration ring 5 is installed in the bearing base 1 and the bearing housing 2. The circumferential angle of the sector-shaped connecting plate 502 is 45° and the axial thickness is 4mm. The sector-shaped connecting plate 502 is embedded in the sector-shaped groove 104 of the base and the sector-shaped groove 204 of the housing. The circumferential sidewall of the sector-shaped connecting plate 502 is in close contact with the groove wall surface of the sector-shaped groove 104 of the base and the sector-shaped groove 204 of the housing, which fixes the vibration ring 5 circumferentially and allows the vibration ring 5 to perform axial reciprocating vibration.

[0036] like Figure 4 and Figure 10 As shown, a stepped shaft 603 is provided on the lower end face of the bearing end cover 6, and a mandrel hole 504 is correspondingly opened in the middle of the annular mandrel 503. The upper small diameter shaft of the stepped shaft 603 is interference-fitted in the mandrel hole 504, and the end face of the upper large diameter shaft is in contact with the upper end face of the annular mandrel 503. A pressure equalization cavity 601 is opened in the upper end face of the bearing end cover 6. Multiple fan-shaped pressure equalization blocks 602 are evenly distributed in the circumferential direction on the pressure equalization cavity 601 in two inner and outer rings. The circumferential spacing between the fan-shaped pressure equalization blocks 602 forms the pressure equalization groove of the pressure equalization cavity 601. The pressurized gas flows evenly in the pressure equalization cavity through the pressure equalization groove. An air inlet channel 604 is also opened in the center of the stepped shaft 603, which passes through the bottom end face of the stepped shaft 603 and the pressure equalization cavity 601.

[0037] The inner ring of the fan-shaped pressure equalizing block 602 consists of three fan-shaped pressure equalizing blocks 602 with a circumferential angle of 120°, forming the first group. The outer ring of the fan-shaped pressure equalizing block 602 consists of six fan-shaped pressure equalizing blocks 602 with a circumferential angle of 60°, forming the second group. The two groups of fan-shaped pressure equalizing blocks 602 together form the support structure of the composite throttle 7.

[0038] like Figure 11 and Figure 12 As shown, a composite throttle 7 is attached to the upper axial end face of the fan-shaped pressure equalizing block 602, and the outer circumferential side wall of the composite throttle 7 is sealed to the bearing end cover 6; multiple air chambers 701 are evenly distributed along the circumferential direction on the lower axial end face of the composite throttle 7, and multiple static pressure shallow chambers 703 are provided on the lower axial end face corresponding to the positions of the air chambers 701. The air chambers 701 and the static pressure shallow chambers 703 are connected through throttle holes 702, and the circumferential position of the air chambers 701 corresponds to the pressure equalizing groove formed between the multiple fan-shaped pressure equalizing blocks 602 located on the outer ring, so as to supply air to the orifice throttle.

[0039] The composite throttle 7 has an axial thickness of 4~6mm, an air chamber 701 with a diameter of 1.8~2.0mm, a static pressure shallow chamber 703 with a diameter of 1.8~2.0mm and an axial depth of 0.1~0.2mm, and a throttle orifice 702 with a diameter of 0.15~0.30mm and an axial length of 0.8~1.0mm.

[0040] Multiple threaded holes are evenly distributed along the circumference on the upper end face of the stepped shaft 603 between the large diameter shaft and the annular mandrel 503. The bearing end cover 6 and the vibration ring 5 are fixedly connected together by the threaded holes and bolts.

[0041] When the composite throttle 7 is working, a portion of the gas enters the gas chamber 701 opened on the composite throttle 7, and after being throttled by the throttling orifice 702, it enters the static pressure shallow chamber 703, forming a high-pressure bearing gas film in and around the perforated throttle. Meanwhile, a portion of the gas is throttled through the porous graphite matrix and enters the bearing clearance, forming a uniform gas film pressure around the perforated throttle. This creates a sealing effect on the high-pressure bearing gas film at the bearing center and the perforated throttle, maintaining the gas film pressure in the bearing clearance and improving the bearing capacity and stiffness.

[0042] like Figure 3 and Figure 13 As shown, the elastic ring 4 is installed inside the bearing base 1 and the bearing housing 2. The lead wires of the piezoelectric sheet 404 attached to the elastic ring 4 pass through the base wiring hole 103 and the housing wiring hole 203 respectively and are connected to the piezoelectric shunt circuit. The resistors and inductors in the piezoelectric shunt circuit are connected in series or in parallel.

[0043] The assembly process and working principle of the composite throttling static pressure gas thrust bearing are as follows: First, the preload ring 3 is installed into the damper mounting groove 101. The positioning plunger 302 cooperates with the preload ring anti-rotation groove 102 in the damper mounting groove 101 to circumferentially fix the preload ring 3. Then, the elastic ring 4 with the piezoelectric sheet 404 attached is installed into the damper mounting groove 101. The inner boss 401 of the elastic ring 4 abuts against the upper end face of the preload ring 3. The anti-rotation plunger 403 of the elastic ring 4 cooperates with the damper anti-rotation groove 301 on the preload ring 3 to circumferentially fix the elastic ring 4. At the same time, the elastic ring 4 with the piezoelectric sheet 404 attached is installed into the elastic ring mounting groove 201 in the bearing housing 2. The inner boss 401 of the elastic ring 4 abuts against the bottom surface of the elastic ring mounting groove 201. The anti-rotation plunger 403 of the elastic ring 4 cooperates with the elastic ring anti-rotation groove 202 to circumferentially fix the elastic ring 4.

[0044] After the elastic ring 4 with piezoelectric sheet 404 attached is installed into the bearing base 1 and bearing housing 2, the vibration ring 5 is simultaneously installed into the damper mounting groove 101 and the elastic ring mounting groove 201. The axial lower end face of the annular pressure block 501 abuts against the outer boss 402 of the elastic ring 4 in the bearing base 1, and the axial upper end face of the annular pressure block 501 abuts against the outer boss 402 of the elastic ring 4 in the bearing housing 2. The inner and outer circumferential walls of the annular pressure block 501 fit against the inner and outer circumferential walls of the damper mounting groove 101 and the elastic ring mounting groove 201. The circumferential sidewall of the fan-shaped connecting plate 502 is tightly attached to the groove wall of the fan-shaped groove 104 of the base and the fan-shaped groove 204 of the housing to circumferentially fix the vibration ring 5. Finally, the bearing base 1 and the bearing housing 2 are pre-tightened by bolt group. After the bearing base 1 and bearing housing 2 are assembled, the stepped shaft 603 of the bearing end cover 6 is inserted into the spindle hole 504 of the vibration ring 5, and the vibration ring 5 and bearing end cover 6 are connected by bolts. Then, epoxy resin adhesive is evenly applied to the axial upper end face of the fan-shaped pressure equalizing block 602 of the bearing end cover 6, and the bearing end cover 6 and the composite throttle 7 are connected by adhesive. The outer circumferential sidewall of the composite throttle 7 and the installation gap between the bearing end cover 6 and the composite throttle 7 are sealed.

[0045] To eliminate the installation gap between the elastic ring 4 and the vibration ring 5 and to adjust the initial preload of the elastic ring 4, the preload screw is inserted from the bottom of the bearing base 1 into the preload threaded hole in the anti-rotation groove 102 of the preload pressure ring. The preload screw is tightened so that its working end abuts against the axial lower end face of the positioning plunger 302 of the preload pressure ring 3. By adjusting the preload screw, it pushes the preload pressure ring 3 to squeeze the elastic ring 4 in the axial direction, thereby eliminating the installation gap between the elastic ring 4 and the annular pressure block 501 and adjusting the preload of the elastic ring 4.

[0046] When the composite throttling static pressure gas thrust bearing is working, external pressurized gas is delivered to the equalizing chamber 601 through the air inlet channel 604 on the back of the bearing end cover 6. After being throttled by the composite throttling device 7, the gas enters the bearing clearance, forming a load-bearing lubricating gas film within the bearing clearance. During bearing operation, the eddies generated within the lubricating gas film cause the bearing end cover 6 to vibrate axially. The bearing end cover 6 transmits the vibration to the connected vibration ring 5, causing the annular pressure block 501 to compress the elastic ring 4 inside the bearing base 1 and the bearing housing 2. The elastic ring 4 resists the axial load through its own elastic deformation. At the same time, the piezoelectric sheet 404 attached to the elastic ring 4 converts the strain energy of the elastic ring 4 into electrical energy. The electrical energy generated by the piezoelectric sheet 404 is consumed through the piezoelectric shunt circuit, providing piezoelectric shunt damping for the bearing. The vibration amplitude of the bearing decreases and tends to stabilize.

[0047] This invention involves installing an elastic ring with a piezoelectric element attached inside the bearing base and bearing housing. When the bearing end cover vibrates axially due to gas film eddy current disturbance, the annular pressure block squeezes the elastic ring at both ends of the bearing, causing the elastic ring to undergo elastic deformation and store vibration energy. The piezoelectric element converts the strain energy of the elastic ring into electrical energy, and the electrical energy generated by the piezoelectric element is consumed through a piezoelectric shunt circuit. This provides piezoelectric shunt damping for the composite throttling hydrostatic gas thrust bearing, improves the stability of the bearing, enables oil-free operation of the hydrostatic gas bearing, and broadens the application scenarios of hydrostatic gas bearings.

[0048] The above description is only used to illustrate the technical solution of the present invention and is not intended to limit it. Any other modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention, as long as they do not depart from the spirit and scope of the technical solution of the present invention, should be covered within the scope of the claims of the present invention.

Claims

1. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle in a wafer thinning machine, characterized in that: It includes a bearing base (1), a bearing housing (2), a bearing end cover (6) and a composite throttle (7) connected in sequence along the axial direction, as well as a pre-tightening ring (3), an elastic ring (4) and a vibration ring (5) for transmitting the vibration motion of the bearing end cover (6) arranged in the axial direction between the bearing base (1) and the bearing housing (2), wherein an elastic ring (4) is provided at each of the two ends of the vibration ring (5). The bearing base (1) and bearing housing (2) are respectively provided with coaxial annular cylindrical cavities on their corresponding connecting surfaces. The bearing base (1) and bearing housing (2) are respectively provided with a coaxial diameter and an axially penetrating center hole (105) in the center of the bearing base (1) and the housing center hole (205). The cylinders between the center hole (105) of the base and the center hole (205) of the housing and their outer circumference are respectively provided with damper mounting grooves (101) and elastic ring mounting grooves (201) of the same inner and outer diameter. Multiple base sector grooves (104) and housing sector grooves (204) evenly distributed along the circumferential direction are respectively provided on the end faces of the cylinders between the damper mounting groove (101) and the center hole (105) of the base and between the elastic ring mounting groove (201) and the center hole (205) of the housing. The pre-tightening ring (3) and the elastic ring (4) are two ring structures with the same inner and outer diameters. Inner bosses (401) and outer bosses (402) are evenly spaced along the circumferential direction on both axial end faces of the elastic ring (4), and the inner bosses (401) and outer bosses (402) are staggered in the circumferential direction. Piezoelectric sheets (404) are attached to the end faces of the elastic ring (4) between adjacent inner bosses (401) and adjacent outer bosses (402), and after attachment, the axial direction of the piezoelectric sheets (404) is... The height is lower than the thickness of the inner boss (401) or the outer boss (402); a pre-tightening ring (3) and an elastic ring (4) are sequentially connected in the damper mounting groove (101). The two end faces of the pre-tightening ring (3) are respectively in contact with the bottom surface of the damper mounting groove (101) and the inner boss (401) of the elastic ring (4). An elastic ring (4) is connected in the elastic ring mounting groove (201). The inner boss (401) of the elastic ring (4) is in contact with the bottom surface of the elastic ring mounting groove (201). The vibration ring (5) is composed of a coaxial annular pressure block (501) and an annular spindle (503) connected by multiple fan-shaped connecting plates (502) evenly distributed along the circumference. The upper and lower ends of the annular pressure block (501) are respectively fitted into the fan-shaped groove (104) of the base and the fan-shaped groove (204) of the shell. The two axial end faces of the annular pressure block (501) are respectively connected to two... The outer protrusion (402) of the elastic ring (4) is in contact with the inner and outer circumferential walls of the annular pressure block (501) and the inner and outer circumferential walls of the damper mounting groove (101) and the elastic ring mounting groove (201). The fan-shaped connecting plate (502) is simultaneously embedded in the fan-shaped groove (104) of the base and the fan-shaped groove (204) of the shell. The circumferential sidewall of the fan-shaped connecting plate (502) is in close contact with the groove wall of the fan-shaped groove (104) of the base and the fan-shaped groove (204) of the shell. The lower end face of the bearing end cover (6) is provided with a stepped shaft (603), and the middle part of the annular mandrel (503) is provided with a mandrel hole (504). The upper small diameter shaft of the stepped shaft (603) is interference-fitted in the mandrel hole (504), and the end face of the upper large diameter shaft is in contact with the upper end face of the annular mandrel (503). The upper end face of the bearing end cover (6) is provided with a pressure equalization chamber (601). Multiple fan-shaped pressure equalization blocks (602) are evenly distributed in the circumferential direction on the pressure equalization chamber (601) in two inner and outer rings. The circumferential spacing between the fan-shaped pressure equalization blocks (602) forms the pressure equalization groove of the pressure equalization chamber (601). The center of the stepped shaft (603) is also provided with an air intake channel (604) that passes through the bottom end face of the stepped shaft (603) and the pressure equalization chamber (601). The upper axial end face of the fan-shaped pressure equalizing block (602) is attached with a composite throttle (7), and the outer circumferential side wall of the composite throttle (7) is sealed to the bearing end cover (6); multiple air chambers (701) are evenly distributed along the circumferential direction on the lower axial end face of the composite throttle (7), and multiple static pressure shallow chambers (703) are set on the lower axial end face corresponding to the positions of the air chambers (701). The air chambers (701) and the static pressure shallow chambers (703) are connected through throttle holes (702), and the circumferential position of the air chambers (701) corresponds to the pressure equalizing groove formed between the multiple fan-shaped pressure equalizing blocks (602) located on the outer ring.

2. The composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: The elastic ring (4) is provided with a circumferential fixing structure between the pre-tightening ring (3) and the bearing housing (2). Two anti-rotation plungers (403) are symmetrically arranged along the circumferential direction on the elastic ring (4) located between the two piezoelectric plates (404). The upper axial end face of the pre-tightening ring (3) and the bottom surface of the elastic ring mounting groove (201) are respectively provided with damper anti-rotation groove (301) and elastic ring anti-rotation groove (202) corresponding to the anti-rotation plungers (403). The elastic ring (4) is circumferentially fixed to the pre-tightening ring (3) and the bearing housing (2) through the cooperation of the anti-rotation plungers (403) with the damper anti-rotation groove (301) and the elastic ring anti-rotation groove (202).

3. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle in a wafer thinning machine according to claim 1, characterized in that: A circumferential fixing structure is provided between the pre-tightening ring (3) and the bearing base (1). Multiple positioning plungers (302) are provided along the circumferential direction on the axial lower end face of the pre-tightening ring (3). A pre-tightening ring anti-rotation groove (102) is provided on the bottom surface of the damper mounting groove (101) corresponding to the positioning plungers (302). The pre-tightening ring (3) and the bearing base (1) are circumferentially fixed by the cooperation between the positioning plungers (302) and the pre-tightening ring anti-rotation groove (102). A pre-tightening threaded hole penetrating the bottom surface of the bearing base (1) and the damper mounting groove (101) is also provided in the pre-tightening ring anti-rotation groove (102).

4. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: The elastic ring (4) has a thickness of 0.8~1.2mm, the inner boss (401) and the outer boss (402) have a thickness of 0.8~1.0mm and a circumferential angle of 12°~18°, and the interval angle between two adjacent inner bosses (401) or outer bosses (402) is 28°~32°; the piezoelectric sheet (404) has a length of 8~12mm, a width of 6~8mm, and an axial thickness of 0.3~0.5mm.

5. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: The bearing base (1) has a base wiring hole (103) that communicates with the damper mounting groove (101) on its outer cylindrical surface. The bearing housing (2) has a housing wiring hole (203) that communicates with the elastic ring mounting groove (202) on its outer cylindrical surface. The lead wires of the piezoelectric sheet (404) on the elastic ring (4) pass through the base wiring hole (103) and the housing wiring hole (203) respectively and are connected to the piezoelectric shunt circuit. The resistors and inductors in the piezoelectric shunt circuit are connected in series or in parallel.

6. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: The circumferential angle of the base sector groove (104) and the shell sector groove (204) are both 45° and the groove depth is 3mm; the circumferential angle of the sector connecting plate (502) is 45° and the axial thickness is 4mm.

7. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: The sector-shaped equalizing blocks (602) located in the inner ring consist of three sector-shaped equalizing blocks (602) with a circumferential angle of 120°, forming the first group. The sector-shaped equalizing blocks (602) located in the outer ring consist of six sector-shaped equalizing blocks (602) with a circumferential angle of 60°, forming the second group. The two groups of sector-shaped equalizing blocks (602) together form the support structure of the composite throttle (7).

8. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: The composite throttle (7) has an axial thickness of 4~6mm, a gas chamber (701) diameter of 1.8~2.0mm, a static pressure shallow chamber (703) diameter of 1.8~2.0mm and an axial depth of 0.1~0.2mm; and a throttle orifice (702) diameter of 0.15~0.30mm and an axial length of 0.8~1.0mm.

9. A composite throttling hydrostatic gas thrust bearing for an air-bearing spindle of a wafer thinning machine according to claim 1, characterized in that: Multiple threaded holes are evenly distributed along the circumferential direction on the connecting end face between the bearing base (1) and the bearing housing (2), and are fixed together by bolts; multiple threaded holes are evenly distributed along the circumferential direction on the upper end face between the upper large diameter shaft of the stepped shaft (603) and the upper end face between the ring spindle (503), and the bearing end cover (6) and the vibration ring (5) are fixed together by the cooperation of threaded holes and bolts.

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