Gas bearing static performance test bench and test method

Abstract

The invention relates to the technical field of detection devices, in particular to a gas bearing static performance test board and a test method. The test board comprises a rack, a mounting table, a loading device, a force sensor, a floating bearing plate, a displacement measuring unit, an insulating part and an on-off detection module. The insulating part enables the floating bearing plate to be electrically insulated from the force sensor, and the on-off detection module is connected with the floating bearing plate and the bearing to be detected to form an electrical loop for detecting the contact state. The contact state of the floating bearing plate and the gas bearing to be detected is detected through the on-off detection module, subjective errors caused by manual judgment are avoided, and reliable suspension criteria are provided for the gas bearing; the invention also provides a first-floating and second-pressing compensation test method and a first-pressing and second-floating test method, so that the elastic deformation error of the mounting surface caused by planeness error and the like which cannot be eliminated by processing is avoided, the gas film thickness measurement precision is ensured, and the measurement precision of the relation curve between the static bearing capacity of the gas bearing and the gas film thickness is ensured.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection devices, in particular to a gas bearing static performance test bench and a test method. BACKGROUND

[0002] Gas bearings are widely used in precision machinery, aerospace and other fields due to their low friction, high speed, no pollution and other advantages. However, the existing static performance test bench lacks accurate contact judgment means, and generally uses artificial light observation, paper or plastic plug gauge and other methods to detect the contact state, which not only has strong subjectivity and low accuracy, but also may damage the stability of the gas film, even scratch the precision surface of the gas bearing and the bearing part, seriously affecting the reliability of the test results and the product yield; in addition, the flatness error of mechanical parts cannot be completely eliminated, and the measured gas bearing and its installation interface will be elastically deformed under load, which will mix into the displacement measurement value, resulting in distortion of the gas film thickness measurement, and further affecting the measurement accuracy of the relationship curve between the bearing capacity and the gas film thickness. SUMMARY

[0003] The technical problem to be solved by the present application is to solve at least one of the above technical problems.

[0004] The solution to the technical problem of the present application is a gas bearing static performance test bench, comprising: a rack; a mounting table arranged on the rack for fixing a gas bearing to be measured; a loading device arranged on the rack for applying an external load to the gas bearing to be measured; a force sensor arranged at the driving end of the loading device for detecting the load applied by the loading device; an up-floating bearing plate arranged at the bottom of the force sensor for bearing the up-floating pressure of the gas film of the gas bearing to be measured; a displacement measurement unit arranged on the rack, the measurement end of which is arranged opposite to the lower surface of the up-floating bearing plate, for measuring the displacement of the lower surface of the up-floating bearing plate; an insulating part clamped between the force sensor and the up-floating bearing plate for electrically insulating the up-floating bearing plate from the force sensor; and an on-off detection module electrically connected to the up-floating bearing plate and the gas bearing to be measured through wires to form an electrical circuit for detecting the conduction state between the two, wherein the gas bearing to be measured is made of conductive material.

[0005] As a further improvement of the above technical solution, the loading device comprises a driving device, a guide shaft and a radial air bearing, the driving device is arranged on the rack, one end of the guide shaft is connected to the output end of the driving device, the other end of the guide shaft is connected to the force sensor, and the radial air bearing is arranged on the rack and sleeved on the guide shaft.

[0006] As a further improvement of the above technical solution, the driving device is a voice coil motor, a stator of the voice coil motor is fixed on the frame, and a rotor of the voice coil motor is fixedly connected with the guide shaft to drive the guide shaft to move in the axial direction.

[0007] As a further improvement of the above technical solution, the displacement measuring unit includes four laser interferometers, each of which includes a corner cube prism and a laser sensor matched with the corner cube prism, four corner cube prisms are respectively arranged in four corner regions of the lower surface of the upper floating bearing plate, and the laser sensors are arranged on the frame and correspond to the corner cube prisms one by one.

[0008] As a further improvement of the above technical solution, it further includes a gas floating ball hinge and a horizontal attitude adjusting mechanism, one end of the gas floating ball hinge is connected with the driving end of the loading device, the other end of the gas floating ball hinge is connected with the force sensor, the horizontal attitude adjusting mechanism is arranged on the frame, and the driving end of the horizontal attitude adjusting mechanism is in contact with the top surface of the upper floating bearing plate to adjust the horizontal attitude of the upper floating bearing plate.

[0009] As a further improvement of the above technical solution, the horizontal attitude adjusting mechanism includes four groups of driving units, the driving units are symmetrically arranged at four corners of the upper floating bearing plate, each group of driving units includes an adjusting motor, an adjusting screw rod and an adjusting sliding block, the adjusting motor is arranged on the frame, the adjusting screw rod is coaxially arranged with the driving end of the adjusting motor, the adjusting sliding block is threadedly connected with the adjusting screw rod, and the adjusting sliding block is in contact with the top surface of the upper floating bearing plate.

[0010] As a further improvement of the above technical solution, it further includes a machine vision unit and a double-axis air floating platform, the machine vision unit includes at least four industrial cameras arranged on the frame, the industrial cameras are used to respectively collect images of visual markers arranged on the upper floating bearing plate and the mounting table, the double-axis air floating platform is arranged on the frame, the mounting table is arranged on the driving end of the double-axis air floating platform, the double-axis air floating platform is used to drive the mounting table to move in translation in a horizontal plane, and the industrial cameras are in communication connection with the double-axis air floating platform.

[0011] As a further improvement of the above technical solution, the double-shaft air floating platform comprises an X-axis adjusting device and a Y-axis adjusting device, the X-axis adjusting device comprises a first motor, a first air floating screw rod, a first air floating guide rail and a first air floating sliding block, the first motor is arranged on the rack, the first air floating screw rod is coaxially arranged with the driving end of the first motor, the first air floating guide rail is arranged on the rack, the first air floating sliding block is in sliding connection with the first air floating guide rail, and the first air floating sliding block is in threaded connection with the first air floating screw rod; the Y-axis adjusting device comprises a second motor, a second air floating screw rod, a second air floating guide rail and a second air floating sliding block, the second motor is arranged on the rack, the second air floating screw rod is coaxially arranged with the driving end of the second motor, the second air floating guide rail is arranged on the rack and is arranged perpendicularly to the first air floating guide rail, the second air floating sliding block is in sliding connection with the second air floating guide rail, and the second air floating sliding block is in threaded connection with the second air floating screw rod, and the mounting table is arranged on the second air floating sliding block.

[0012] A gas bearing static performance test method based on a pre-floating and post-pressing compensation test, which adopts the gas bearing static performance test table according to any one of the above technical solutions and comprises the following steps: controlling the loading device to make the upper floating bearing plate and the gas bearing to be tested disengage from contact, and setting the force sensor to zero; controlling the loading device to make the lower surface of the upper floating bearing plate contact and adhere to the upper surface of the gas bearing to be tested; verifying the repeatability of the structural deformation through multiple loading and unloading cycles of the loading device; driving the upper floating bearing plate to press against the gas bearing to be tested through the loading device at a series of loads covering the expected test range, and obtaining multiple sets of load and displacement data through the force sensor and the displacement measuring unit, and establishing a compensation relationship of the structural deformation of the test table based on the multiple sets of load and displacement data; supplying gas to the gas bearing to be tested to make the upper floating bearing plate float; applying a test load to the upper floating bearing plate through the loading device, and obtaining real-time bearing force and displacement measurement values through the force sensor and the displacement measuring unit; according to the bearing force, obtaining the corresponding test table structural deformation amount based on the compensation relationship, calibrating the displacement measurement value, and obtaining the actual gas film thickness; analyzing the relationship between the bearing force and the actual gas film thickness, and obtaining the static performance parameters of the gas bearing to be tested.

[0013] The gas bearing static performance test method based on the pre-pressing and post-floating test adopts the gas bearing static performance test table according to any one of the above, and comprises the following steps: controlling the loading device to make the upper floating bearing plate and the gas bearing to be tested disengage from contact, and zeroing the force sensor; controlling the loading device to make the lower surface of the upper floating bearing plate contact and adhere to the upper surface of the gas bearing to be tested; verifying the repeatability of the structural deformation through multiple loading and unloading cycles of the loading device; applying a predetermined pre-pressing load to the upper floating bearing plate through the loading device, zeroing the indication of the displacement measuring unit in the state of maintaining the pre-pressing load and the system stability; supplying gas to the gas bearing to be tested under the condition of maintaining the pre-pressing load; obtaining the bearing force generated by the gas bearing to be tested through the force sensor, and obtaining the displacement of the upper floating bearing plate through the displacement measuring unit, which is the actual gas film thickness; analyzing the relationship between the bearing force and the actual gas film thickness to obtain the static performance parameters of the gas bearing to be tested.

[0014] The rack provides stable support; the mounting table fixes the gas bearing to be tested, ensures the position fixed during the test, and avoids the test data distorted due to displacement; the loading device applies controllable external load to the gas bearing to be tested, can realize the step-by-step increase of the load, and simulates the actual stress scenario of the gas bearing; the force sensor detects the load force applied by the loading device in real time, accurately collects the load data in the loading process, and provides basis for subsequent performance parameter calculation; the upper floating bearing plate transfers the load of the loading device and serves as one end of the electric circuit; the displacement measuring unit measures the displacement of the lower surface of the upper floating bearing plate, indirectly obtains the gas film thickness data, and provides basic data for bearing force, static stiffness and other parameter calculation; the insulating part is clamped between the force sensor and the upper floating bearing plate, realizes the electrical insulation of the two, avoids the force sensor interfering with the conduction state detection of the electric circuit, and avoids the electric circuit conduction detection affecting the signal of the force sensor; the on-off detection module forms an electric circuit with the upper floating bearing plate and the gas bearing to be tested through wires, and monitors the current or resistance value of the circuit in real time to determine whether the two are in contact. The contact state of the upper floating bearing plate and the gas bearing to be tested is detected through the on-off detection module, which avoids the subjective error of manual judgment, does not need to directly contact the gas film or the precision surface, completely eliminates the risk of scratching the components and affecting the performance of the gas film, provides reliable suspension criteria for the gas bearing, captures the contact moment in real time and immediately stops loading, ensures the measurement accuracy of the bearing force and other parameters, and combines the gas film thickness data to comprehensively calculate the static performance indicators and provide accurate basis for technical optimization. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 This is a schematic diagram of the structure of a test bench according to one embodiment of the present invention.

[0016] Fig. 2 This is a cross-sectional view of a test bench according to one embodiment of the present invention.

[0017] Fig. 3 This is a schematic diagram of the structure of a biaxial air flotation platform according to one embodiment of the present invention.

[0018] Reference numerals in the attached figures: 100-Frame, 110-Mounting platform, 120-Gas bearing under test, 200-Loading device, 210-Drive device, 220-Guide shaft, 230-Radial air bearing, 300-Force sensor, 400-Floating support plate, 500-Displacement measurement unit, 510-Pyramidal prism, 520-Laser sensor, 600-Insulating component, 610-Continuity detection module, 700-Air bearing ball joint, 800-Horizontal attitude adjustment mechanism, 810-Adjusting motor, 820-Adjusting lead screw, 830-Adjusting slider, 900-Industrial camera, 910-Dual-axis air bearing platform, 911-First motor, 912-First air bearing lead screw, 913-First air bearing guide rail, 914-First air bearing slider, 915-Second motor, 916-Second air bearing lead screw, 917-Second air bearing guide rail, 918-Second air bearing slider. Detailed Implementation

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments have been briefly explained above. Obviously, the described drawings are only a part of the embodiments of the present invention, and not all of them. Those skilled in the art can obtain other design schemes and drawings based on these drawings without creative effort.

[0020] The following will clearly and completely describe the concept, specific structure, and technical effects of the present invention in conjunction with embodiments and accompanying drawings, so as to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of them. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention. Furthermore, all connections / linkages mentioned herein do not simply refer to direct connection of components, but rather to the ability to form a better connection structure by adding or reducing connecting accessories according to specific implementation conditions. The various technical features in this invention can be combined interactively without contradicting each other.

[0021] Gas bearings, with their advantages of low friction, high speed, and no pollution, are widely used in precision machinery, aerospace, and other fields. However, existing static performance testing benches lack precise contact judgment methods, and generally rely on manual observation under light or inserting paper or plastic feeler gauges to check the contact state. This not only suffers from strong subjectivity and low accuracy, but may also damage the stability of the gas film and even scratch the precision surfaces of the gas bearing and the load-bearing components, seriously affecting the reliability of test results and product yield. Considering that the flatness error of the part plane cannot be eliminated, elastoplastic deformation may occur at the mounting surface of the tested gas bearing, thus affecting the accuracy of gas film thickness measurement and consequently the accuracy of the measurement of the relationship between the gas bearing's load-bearing capacity and gas film thickness. Existing static characteristic testing benches use positioning pins to center the tested gas bearing for tilt characteristic measurement. Considering that the two surfaces of the gas film are not in contact, the centering accuracy is difficult to guarantee, thus affecting the accuracy of tilt characteristic measurement.

[0022] Therefore, this invention proposes a static performance testing bench for gas bearings, referring to... Figs. 1-3 It includes: a frame 100; a mounting platform 110, disposed on the frame 100, for fixing the gas bearing 120 to be tested; a loading device 200, disposed on the frame 100, for applying an external load to the gas bearing 120 to be tested; a force sensor 300, disposed at the drive end of the loading device 200, for detecting the load force applied by the loading device 200; an upward bearing plate 400, disposed at the bottom of the force sensor 300, for bearing the upward buoyancy pressure of the gas film of the gas bearing 120 to be tested; and a displacement measuring unit 500, disposed on the frame 100. The measuring end of the upper floating support plate 400 is positioned opposite to the lower surface of the upper floating support plate 400 to measure the displacement of the lower surface of the upper floating support plate 400; the insulating component 600 is sandwiched between the force sensor 300 and the upper floating support plate 400 to electrically insulate the upper floating support plate 400 from the force sensor 300; the continuity detection module 610 is electrically connected to the upper floating support plate 400 and the gas bearing 120 under test via wires to form an electrical circuit for detecting the continuity between the two, wherein the gas bearing 120 under test is made of conductive material.

[0023] The frame 100 provides stable support; the mounting platform 110 fixes the gas bearing 120 under test, ensuring its position remains fixed during testing to avoid data distortion due to displacement; the loading device 200 applies a controllable external load to the gas bearing 120 under test, allowing for gradual load increases to simulate the actual stress scenario of the gas bearing; the force sensor 300 detects the load force applied by the loading device 200 in real time, accurately collecting load data during the loading process to provide a basis for subsequent performance parameter calculations; the floating bearing plate 400 transmits the load of the loading device 200 and also serves as one end of the electrical circuit; displacement measurement... Unit 500 measures the displacement of the lower surface of the floating support plate 400, indirectly obtaining air film thickness data, providing basic data for calculating parameters such as bearing capacity and static stiffness; the insulating component 600 is sandwiched between the force sensor 300 and the floating support plate 400 to achieve electrical insulation between the two, avoiding interference from the force sensor 300 with the continuity detection of the electrical circuit, and at the same time avoiding the continuity detection of the electrical circuit from affecting the signal of the force sensor 300; the continuity detection module 610 forms an electrical circuit with the floating support plate 400 and the gas bearing 120 under test through wires, and monitors the current or resistance value of the circuit in real time to determine whether the two are in contact. The continuity detection module 610 detects the contact state between the floating support plate 400 and the gas bearing 120 under test, avoiding subjective errors caused by manual judgment. It also eliminates the risk of scratching parts and affecting the performance of the gas film without direct contact with the gas film or precision surfaces, providing a reliable levitation criterion for the gas bearing. The module captures the moment of contact in real time and stops loading immediately, ensuring the accuracy of the measurement of parameters such as load-bearing capacity. Combined with the gas film thickness data, static performance indicators can be comprehensively calculated, providing an accurate basis for technical optimization.

[0024] During performance testing, the air supply system is activated to supply air to the gas bearing 120 under test. An air film is formed between the floating support plate 400 and the gas bearing. The floating support plate 400, made of conductive material, is suspended under the pressure of the air film. The continuity detection circuit consisting of the continuity detection module 610, the floating support plate 400, and the gas bearing 120 under test is in an open state. The loading device 200 drives the floating support plate 400 to move slowly downward, gradually increasing the external load on the gas bearing. During the process, the force sensor 300 collects load data in real time, and the displacement measurement unit 500 records it synchronously. The displacement of the floating bearing plate 400 is monitored; the continuity detection module 610 monitors the changes in current or resistance in the electrical circuit in real time: if the current value is lower than the set threshold or the resistance value is higher than the set threshold, it is determined that the gas bearing remains in a suspended state and loading continues; if the current value is higher than the set threshold or the resistance value is lower than the set threshold, it is determined that the floating bearing plate 400 has made physical contact with the gas bearing and the loading device 200 is immediately controlled to stop loading; combined with the load values ​​recorded under different loading forces and the air film thickness data obtained by the displacement measurement unit 500, the static performance parameters such as the bearing capacity and static stiffness of the gas bearing are calculated.

[0025] Traditional linear guides suffer from friction and movement gaps, which can easily introduce hysteresis errors and directional deviations during the application of small loads, affecting the accuracy of load transmission and causing distortion in load-bearing capacity measurements. Therefore, in one embodiment, the loading device 200 includes a drive device 210, a guide shaft 220, and a radial air bearing 230. The drive device 210 is mounted on the frame 100. One end of the guide shaft 220 is connected to the output end of the drive device 210, and the other end is connected to the force sensor 300. The radial air bearing 230 is mounted on the frame 100 and sleeved around the guide shaft 220. The contactless support of the radial air bearing 230 avoids the mechanical friction of traditional guide rails, eliminates the interference of friction on load transmission, and makes the load applied to the gas bearing closer to the set value, significantly reducing load measurement error. The radial air bearing 230 constrains the radial displacement of the guide shaft 220, ensuring that the loading force is always transmitted in the preset direction, avoiding uneven load distribution caused by guide deviation, and ensuring the accuracy of contact judgment and the reliability of performance parameter calculation. The frictionless loading method can reduce external interference, more accurately capture the gas bearing's response to load, and provide more realistic data support.

[0026] When the upper floating bearing plate 400 rises, it needs to overcome the frictional force of the portion above the upper floating bearing plate 400. Conventional motors and transmission systems have backlash, backlash, and friction, which may increase the error in the curve relating air film thickness and load-bearing capacity. Therefore, in one embodiment, the drive device 210 is a voice coil motor. The stator of the voice coil motor is fixed on the frame 100, and the mover of the voice coil motor is fixed to the guide shaft 220 to drive it to move axially. The voice coil motor has advantages such as stable thrust, fast response speed, and high resolution. Its mover and stator work based on magnetic levitation or non-contact operation, further eliminating friction in mechanical transmission. Combined with radial air floatation guidance, a frictionless loading chain is constructed, improving the dynamic response, thrust stability, and displacement resolution of the loading process, meeting the requirements for fine depiction of the static stiffness curve of ultra-high precision gas bearings.

[0027] Single-point displacement measurement cannot reflect the overall attitude change of the floating support plate 400. If the support plate tilts or deflects, it will cause deviation in the calculation of the air film thickness, affecting the accuracy of the load-bearing capacity and stiffness assessment. Therefore, in one embodiment, the displacement measurement unit 500 includes four laser interferometers. Each laser interferometer includes a corner prism 510 and a laser sensor 520 that cooperates with the corner prism 510. The four corner prisms 510 are respectively disposed in the four corner areas of the lower surface of the floating support plate 400, and the laser sensors 520 are disposed on the frame 100 and correspond one-to-one with the corner prisms 510. By using displacement measurement points at the four corners, not only can the average gas film thickness be accurately calculated, but also the tilt and deflection of the bearing plate can be monitored in real time, providing data support for tilt stiffness calculation and realizing multi-dimensional performance evaluation of thickness and attitude, comprehensively reflecting the static performance of the gas bearing; the laser interferometer has high measurement accuracy, and the original path reflection characteristics of the 510 corner pyramid prism reduce the error caused by optical path offset; the distribution of the four measurement points avoids the randomness of single-point measurement and reduces the influence of factors such as installation deviation and flatness on the measurement results.

[0028] When the loading mechanism is rigidly connected to the floating support plate 400, stress concentration may occur due to initial non-parallel installation or local contact, causing bending moment interference with the force sensor 300 reading and potentially resulting in localized crushing damage. Therefore, in one embodiment, an air-bearing ball joint 700 and a horizontal attitude adjustment mechanism 800 are also included. One end of the air-bearing ball joint 700 is connected to the drive end of the loading device 200, and the other end of the air-bearing ball joint 700 is connected to the force sensor 300. The horizontal attitude adjustment mechanism 800 is mounted on the frame 100, and its drive end is in contact with the top surface of the floating support plate 400 for adjusting the horizontal attitude of the floating support plate 400. The air-bearing ball joint 700 isolates bending moment transmission and self-aligns, solving the problem of local stress concentration caused by initial non-parallelism and avoiding local rupture of the air film and damage to the precision surface of the gas bearing 120 under test. The horizontal attitude adjustment mechanism 800 realizes active calibration of the level of the bearing plate. Combined with the dynamic attitude compensation of the air-bearing ball joint 700, it ensures uniform distribution of air film thickness during loading, making the test conditions closer to the actual working scenario. After adjustment, the drive end of the horizontal attitude adjustment mechanism 800 disengages from the top surface of the upper floating bearing plate 400 to avoid affecting subsequent loading. Without relying on extremely high machining and installation precision, the test bench can adapt to the testing needs of gas bearings of different specifications and installation benchmarks through active adjustment and adaptive compensation, thus expanding the applicability of the test bench.

[0029] Accumulated errors in machining and assembly cause the initial attitude of the floating support plate 400 to tilt, which may not be fully compensated for even using a ball joint. Therefore, in one embodiment, the horizontal attitude adjustment mechanism 800 includes four sets of drive units symmetrically arranged at the four corners of the floating support plate 400. Each set of drive units includes an adjustment motor 810, an adjustment lead screw 820, and an adjustment slider 830. The adjustment motor 810 is mounted on the frame 100. The adjustment lead screw 820 is coaxially rotatably mounted with the drive end of the adjustment motor 810. The adjustment slider 830 is threadedly connected to the adjustment lead screw 820 and is in contact with the top surface of the floating support plate 400. Four sets of drive units are symmetrically arranged at the four corners, supporting independent fine-tuning. This can accurately compensate for the cumulative tilting error caused by processing and installation, ensuring the authenticity and accuracy of the air film thickness measurement. The adjusting slider 830 and the adjusting screw 820 form a threaded pair and are in contact with the top surface of the upper floating support plate 400. This allows for selective pressing down or lifting of the edge of the upper floating support plate 400 to adjust its horizontal posture. Through independent fine-tuning at the four corners, it can be adapted to the testing of gas bearings of different sizes and with different installation standards, expanding the applicability of the test bench.

[0030] The horizontal positional deviation between the mounting platform 110 and the upper floating support plate 400 can cause loading eccentricity, resulting in torque effect and local air film rupture, affecting the measurement accuracy of the gas bearing tilt characteristics and the repeatability of the test. Therefore, in one embodiment, a machine vision unit and a dual-axis air-bearing platform 910 are also included; the machine vision unit includes at least four industrial cameras 900 mounted on the frame 100, forming two sets of binocular vision systems. Two industrial cameras 900 are used to acquire images of visual marks set on the upper floating support plate 400, and two industrial cameras 900 are used to acquire images of visual marks set on the mounting platform 110, thereby calculating the center positional deviation between the two; the dual-axis air-bearing platform 910 is mounted on the frame 100, and the mounting platform 110 is mounted on the drive end of the dual-axis air-bearing platform 910. The dual-axis air-bearing platform 910 is used to drive the mounting platform 110 to perform translational movement in the horizontal plane, and the industrial cameras 900 are communicatively connected to the dual-axis air-bearing platform 910. Images of visual markers on the floating support plate 400 and the gas bearing mounting platform 110 are simultaneously acquired by two industrial cameras 900. The center coordinates of the two visual markers in the camera coordinate system are calculated respectively. Based on the difference between the two center coordinates, the X and Y displacements that the gas bearing mounting platform 110 needs to be adjusted are calculated. The dual-axis air-bearing platform 910 drives the mounting platform 110 to carry the gas bearing 120 under test to perform the calculated displacement until the centers of the two visual markers coincide. This achieves high-precision concentric positioning of the gas bearing 120 under test and the floating support plate 400, improves the measurement accuracy of the gas bearing tilt characteristics, eliminates the risk of off-center loading, and enhances test consistency and repeatability.

[0031] Traditional positioning mechanisms suffer from yaw, pitch, and roll errors that can disturb the air film or scratch precision components. Therefore, in one embodiment, the dual-axis air-bearing platform 910 includes an X-axis adjustment device and a Y-axis adjustment device. The X-axis adjustment device includes a first motor 911, a first air-bearing lead screw 912, a first air-bearing guide rail 913, and a first air-bearing slider 914. The first motor 911 is mounted on the frame 100. The first air-bearing lead screw 912 is coaxially rotatable with the drive end of the first motor 911. The first air-bearing guide rail 913 is mounted on the frame 100. The first air-bearing slider 914 is slidably connected to the first air-bearing guide rail 913 and threadedly connected to the first air-bearing lead screw 912. The Y-axis adjustment device includes a second motor 915, a second air-bearing lead screw 916, a second air-bearing guide rail 917, and a second air-bearing slider 918. The second motor 915 is mounted on the frame 100. The second air-bearing lead screw 916 is coaxially and rotatably mounted with the drive end of the second motor 915. The second air-bearing guide rail 917 is mounted on the frame 100 and is perpendicular to the first air-bearing guide rail 913. The second air-bearing slider 918 is slidably connected to the second air-bearing guide rail 917 and threadedly connected to the second air-bearing lead screw 916. The mounting platform 110 is mounted on the second air-bearing slider 918. The first motor 911 drives the first air-bearing lead screw 912 to rotate, which is converted into the linear motion of the first air-bearing slider 914 along the X-axis, thereby driving the entire Y-axis adjustment device and its mounting platform 110 to move in the X direction. Similarly, the second motor 915 drives the second air-bearing lead screw 916 to rotate, which is converted into the movement of the second air-bearing slider 918 and the mounting platform 110 along the Y direction. The combined motion of the two axes can realize the positioning of the mounting platform 110 at any position in the horizontal plane. The structure of the air-bearing lead screw drive and the air-bearing guide rail ensures smooth movement and no mechanical impact, avoids the vibration interference of traditional mechanisms, protects the precision surface of the gas bearing 120 under test, and does not damage the stability of the air film, ensuring the continuous and reliable testing process.

[0032] In some of the solutions described above in this application, an external load is applied to the gas bearing 120 under test by a loading device 200, and the gas film deformation is obtained by a displacement measurement unit 500 to evaluate its static performance. However, in actual execution, the mechanical structure of the test system, such as the mounting platform 110, connectors, and base, will undergo elastic compression or plastic deformation under load, causing the displacement value measured by the laser interferometer to include structural subsidence that is not due to gas film deformation, resulting in the measured gas film thickness deviating from the true value. Especially for the measurement of gas film thickness at the micron or even submicron level, such errors cannot be ignored and seriously affect the accuracy of the calculation of bearing capacity and static stiffness. In addition, if the loading process is not properly controlled, the descent speed of the floating bearing plate 400 may be too fast, which may cause its lower surface to collide rigidly with the upper surface of the gas bearing. This may introduce initial stress or, in severe cases, scratch the precision air-floating surface, causing the sample to fail and making further testing impossible.

[0033] To address this, this application further proposes a static performance testing method for gas bearings based on a pre-floating and post-pressure compensation test. The method employs a gas bearing static performance testing bench as described in any of the preceding claims and includes the following steps: controlling the loading device 200 to disengage the upper floating support plate 400 from the gas bearing 120 under test, and zeroing the force sensor 300; controlling the loading device 200 to bring the lower surface of the upper floating support plate 400 into contact with and adhere to the upper surface of the gas bearing 120 under test; performing multiple loading and unloading cycles through the loading device 200 to verify the repeatability of structural deformation; driving the upper floating support plate 400 with a series of loads covering the expected test range to press against the gas bearing 120 under test, and then... The force sensor 300 and displacement measurement unit 500 acquire multiple sets of load and displacement data, and establish a compensation relationship for the deformation of the test bench structure based on these data. Gas is supplied to the gas bearing 120 under test, causing the floating support plate 400 to float. A test load is applied to the floating support plate 400 via the loading device 200, and the load-bearing capacity and displacement measurement values ​​are acquired in real time via the force sensor 300 and displacement measurement unit 500. Based on the load-bearing capacity and the compensation relationship, the corresponding deformation of the test bench structure is determined, and the displacement measurement value is calibrated to obtain the actual gas film thickness. The relationship between the load-bearing capacity and the actual gas film thickness is analyzed to obtain the static performance parameters of the gas bearing 120 under test. By pre-calibrating the structural deformation compensation relationship, the measured displacement data is corrected to obtain the true gas film thickness.

[0034] Specifically, when conducting tests: First, the loading device 200 is controlled to raise the floating support plate 400 to a state where it is detached from the gas bearing 120 under test, and the force sensor 300 is zeroed. Then, the floating support plate 400 is slowly driven downward until its lower surface contacts and adheres to the upper surface of the gas bearing. To avoid impact damage caused by high-speed downward pressure, the gas inlet and outlet of the loading device 200 are usually opened, so that it is in a low-pressure floating state, relying on the gravity of the floating support plate 400 to descend slowly and achieve gentle contact. During this process, the resistance or current signal of the continuity detection module 610 is monitored in real time: when the circuit resistance drops suddenly or a conducting current appears, it is determined that the two have made physical contact and completed the initial adhesion.

[0035] Ideally, gravity alone can achieve perfect contact. However, due to residual friction in guiding mechanisms such as linear bearings and ball joints, achieving perfectly parallel contact is often difficult in practice. Therefore, to further ensure uniform contact in the initial state, a small preload, such as force 1 = 10N~20N, needs to be applied. After the system stabilizes, this load is removed, and the loading device 200 is switched to a free state, allowing the floating support plate 400 to naturally rebound and recover under unconstrained conditions. After this process, the floating support plate 400 and the gas bearing surface tend to be parallel and free of initial stress, establishing a reliable benchmark for subsequent measurements.

[0036] Due to machining flatness errors between the lower surface of the gas bearing and the upper surface of the mounting platform 110, and between the lower surface of the mounting platform 110 and the upper surface of the biaxial air-bearing platform 910, progressively accumulating elastic deformation occurs under external loads. For example, when a downward load is applied to the upper floating bearing plate 400, not only is the air film compressed, but also local compression and deformation occur at the microscopic unevenness between the interfaces below, causing the overall structure to sink. This structural sinking can be misinterpreted by the laser interferometer as thinning of the air film, resulting in measurement distortion. To eliminate this effect, this application proposes calibrating the structural deformation compensation value before formal testing. The specific operation is as follows: After initial bonding and zeroing the readings of the four laser interferometers, multiple test loads covering the expected measurement range are sequentially applied via the loading device 200, such as force 2 = 30N, force 3 = 60N, and force 4 = 90N. Each load level is maintained for a sufficient time to ensure system stability, and the average displacement value of the four interferometers is recorded. Subsequently, the load is completely unloaded, and the system is allowed to freely return to its initial position. If the readings are consistent after each return, it indicates that the structural deformation has good repeatability and can be equivalent to a linear or piecewise linear virtual spring model.

[0037] Furthermore, the structural deformation is measured individually for each load level: that is, the interferometer is zeroed in the fit state, a specific load is applied, such as force 5 = 50N, and the interferometer reading is recorded after stabilization. This value is the structural settlement compensation value under that load. By analogy, a complete load-structural deformation compensation curve is established.

[0038] After the compensation calibration is completed, the formal testing phase begins: The floating support plate 400 is restored to a free-floating state, and the interferometer is reset to zero. Compressed gas at a set pressure is supplied to the gas bearing 120 under test to form a complete gas film. Then, the test load is applied through the loading device 200, and the load-bearing force output by the force sensor 300 and the original displacement data output by the interferometer are collected simultaneously.

[0039] Finally, the original displacement value is corrected using a pre-calibrated compensation relationship: the measured displacement under the current load is subtracted from the structural settlement compensation value corresponding to the load, and the difference is the actual air film thickness. Based on multiple sets of corrected bearing capacity and air film thickness data, the static stiffness curve of the gas bearing is plotted, and its nonlinear characteristics, ultimate bearing capacity, and other static performance parameters can be further analyzed.

[0040] To improve testing accuracy, it is recommended to repeat the measurement for the same working condition more than twice and take the average value as the final result; better, 10 or more sets of tests can be performed, the standard deviation of the measurement can be statistically analyzed, and the repeatability and uncertainty level of the system can be evaluated.

[0041] Through the above technical solution, this application effectively separates the structural elastic deformation from the actual air film deformation, significantly improves the authenticity and reliability of air film thickness measurement, and solves the measurement deviation problem caused by the cumulative error of the mechanical system. It is particularly suitable for the research and development verification scenario of high-precision, small air film thickness gas bearings.

[0042] In some of the solutions described above in this application, the pre-floating-then-pressurizing compensation test method can achieve accurate measurement of the air film thickness by calibrating the structural deformation relationship. However, in actual implementation, this method requires additional multi-stage loading to establish a compensation model, making the operation process relatively complex. Furthermore, it relies on historical data interpolation correction, which carries certain risks of system delay and cumulative error.

[0043] To address this, this application further proposes a static performance testing method for gas bearings based on a pre-pressure followed by a floating test. This method employs a gas bearing static performance testing platform as described in any of the preceding claims and includes the following steps: controlling the loading device 200 to disengage the upper floating support plate 400 from the gas bearing 120 under test, and zeroing the force sensor 300; controlling the loading device 200 to bring the lower surface of the upper floating support plate 400 into contact with and adhere to the upper surface of the gas bearing 120 under test; performing multiple loading and unloading cycles using the loading device 200 to verify the repeatability of structural deformation; and using the loading device 200 to push the upper floating support plate 400 into contact with and adhere to the upper surface of the gas bearing 120 under test. A predetermined preload is applied to the bearing plate 400. While maintaining the preload and ensuring system stability, the reading of the displacement measuring unit 500 is zeroed. Under the same preload condition, gas is supplied to the gas bearing 120 under test. The force sensor 300 acquires the bearing force generated by the gas bearing 120, and the displacement measuring unit 500 acquires the displacement of the floating bearing plate 400, which is the actual gas film thickness. The relationship between the bearing force and the actual gas film thickness is analyzed to obtain the static performance parameters of the gas bearing 120 under test. By setting a reasonable initial state, the influence of structural deformation on the measurement results is naturally eliminated, thereby simplifying the testing process and improving real-time performance and reliability.

[0044] Specifically, during testing: First, the loading device 200 is controlled to suspend the upper bearing plate 400 in mid-air, detaching it from the surface of the gas bearing 120 under test, and the force sensor 300 is zeroed to eliminate preload interference. Then, the upper bearing plate 400 is driven to slowly descend, ensuring its lower surface fully contacts the upper surface of the gas bearing. During this process, the resistance or current signal of the continuity detection module 610 is monitored in real time: when the circuit is open, it is determined that physical contact has occurred, completing the initial contact.

[0045] Next, a predetermined preload, such as force γ = 50N, is applied to the floating support plate 400 via the loading device 200, bringing the entire test system, including the mounting platform 110, connectors, and base, into a stable stress state. After the system deformation tends to reach equilibrium, typically for 10–30 seconds, the readings of the four laser interferometers are uniformly set to zero. This zero point corresponds to the reference plane under the current compression state, naturally encompassing the elastic subsidence of all mechanical structures under this load.

[0046] Then, while maintaining the preload constant, compressed gas at a set pressure is supplied to the gas bearing 120 under test to activate its levitation function. As the gas film pressure gradually builds up, the gas bearing applies an upward reaction force, pushing the floating support plate 400 upward against the external load. At this time, four laser interferometers simultaneously record the displacement changes of each angle of the floating support plate 400.

[0047] Since the initial state has been zeroed out under the preload, the displacement increment measured by the laser interferometer is the true air film thickness recovered from the current compression reference, without the need for any further compensation calculations. The average displacement of the four points yields a high-precision average air film thickness; simultaneously, the tilt angle of the bearing plate can be calculated based on the differences between the points, used to evaluate the uniformity of the air film distribution and the bearing's anti-overturning capability.

[0048] Meanwhile, the force sensor 300 continuously outputs the net load-bearing capacity value, which is the upward supporting force generated by the gas bearing. Combined with the real-time collected air film thickness data, a complete curve showing the relationship between load-bearing capacity and air film thickness can be plotted, thereby calculating key static performance parameters such as static stiffness and ultimate bearing capacity.

[0049] It is worth noting that the pre-compression followed by buoyancy method can essentially be considered an ideal equivalent of the pre-buoyancy followed by compression compensation method after compensation processing. This is because in the pre-buoyancy followed by compression method, the measured displacement minus the compensation value is precisely equivalent to the displacement increment measured after zeroing under pre-compression conditions in this method. Therefore, this method not only avoids the complex offline compensation modeling process but also achieves online, real-time, and uncorrected acquisition of the true air film thickness, significantly improving testing efficiency and engineering practicality.

[0050] Through the above technical solution, this application provides a static performance testing method that requires no additional calibration, is easy to operate, and has high measurement accuracy. It is particularly suitable for batch testing and rapid verification testing scenarios, and realizes low-cost and high-reliability static characteristic measurement of gas bearings.

[0051] This invention proposes a pre-float-then-pressure compensation test method and a pre-pressure-then-float test method, which avoids the elastic deformation error of the mounting surface caused by unavoidable flatness errors in processing, and ensures the accuracy of gas film thickness measurement, thereby ensuring the measurement accuracy of the relationship curve between the static bearing capacity and gas film thickness of the gas bearing.

[0052] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited to the embodiments described. Those skilled in the art can make various equivalent modifications or substitutions without departing from the spirit of the present invention, and these equivalent modifications or substitutions are all included within the scope defined by the claims of this application.

Claims

1. A static performance testing bench for gas bearings, characterized in that, include: frame; The mounting platform, set on the frame, is used to fix the gas bearing to be tested; A loading device, mounted on the frame, is used to apply an external load to the gas bearing under test; A force sensor is installed at the drive end of the loading device to detect the load force applied by the loading device; An upper floating support plate is set at the bottom of the force sensor to bear the upward floating pressure of the gas film of the gas bearing to be tested; A displacement measuring unit is mounted on the frame, with its measuring end positioned opposite the lower surface of the upper floating support plate, for measuring the displacement of the lower surface of the upper floating support plate; An insulating component is sandwiched between the force sensor and the upper floating support plate to electrically insulate the upper floating support plate from the force sensor. The continuity detection module is electrically connected to the upper floating support plate and the gas bearing under test respectively through wires to form an electrical circuit for detecting the continuity between the two, wherein the gas bearing under test and the upper floating support plate are made of conductive materials.

2. The gas bearing static performance test bench according to claim 1, characterized in that, The loading device includes a drive unit, a guide shaft, and a radial air bearing. The drive unit is mounted on the frame. One end of the guide shaft is connected to the output end of the drive unit, and the other end of the guide shaft is connected to the force sensor. The radial air bearing is mounted on the frame and is sleeved on the guide shaft.

3. The gas bearing static performance test bench according to claim 2, characterized in that, The driving device is a voice coil motor. The stator of the voice coil motor is fixed on the frame, and the mover of the voice coil motor is fixed to the guide shaft to drive it to move axially.

4. The gas bearing static performance test bench according to claim 1, characterized in that, The displacement measurement unit includes four laser interferometers. Each laser interferometer includes a corner prism and a laser sensor that cooperates with the corner prism. The four corner prisms are respectively arranged in the four corner areas of the lower surface of the upper floating support plate. The laser sensors are arranged on the frame and correspond one-to-one with the corner prisms.

5. The gas bearing static performance test bench according to claim 1, characterized in that: It also includes an air-bearing ball joint and a horizontal attitude adjustment mechanism. One end of the air-bearing ball joint is connected to the drive end of the loading device, and the other end of the air-bearing ball joint is connected to the force sensor. The horizontal attitude adjustment mechanism is mounted on the frame, and the drive end of the horizontal attitude adjustment mechanism is in contact with the top surface of the floating support plate to adjust the horizontal attitude of the floating support plate.

6. The gas bearing static performance test bench according to claim 5, characterized in that: The horizontal attitude adjustment mechanism includes four sets of drive units, which are symmetrically arranged at the four corners of the floating support plate. Each set of drive units includes an adjustment motor, an adjustment screw, and an adjustment slider. The adjustment motor is mounted on the frame. The adjustment screw is coaxially rotatable with the drive end of the adjustment motor. The adjustment slider is threadedly connected to the adjustment screw and is in contact with the top surface of the floating support plate.

7. The gas bearing static performance test bench according to claim 1, characterized in that, It also includes a machine vision unit and a dual-axis air-bearing platform; the machine vision unit includes at least four industrial cameras mounted on the frame, the industrial cameras being used to acquire images of visual markers mounted on the upper floating support plate and the mounting platform respectively; the dual-axis air-bearing platform is mounted on the frame, the mounting platform is mounted on the drive end of the dual-axis air-bearing platform, the dual-axis air-bearing platform being used to drive the mounting platform to perform translational movement in the horizontal plane, and the industrial cameras are communicatively connected to the dual-axis air-bearing platform.

8. The gas bearing static performance test bench according to claim 7, characterized in that, The dual-axis air-bearing platform includes an X-axis adjustment device and a Y-axis adjustment device. The X-axis adjustment device includes a first motor, a first air-bearing lead screw, a first air-bearing guide rail, and a first air-bearing slider. The first motor is mounted on the frame, the first air-bearing lead screw is coaxially rotatable with the drive end of the first motor, the first air-bearing guide rail is mounted on the frame, the first air-bearing slider is slidably connected to the first air-bearing guide rail, and the first air-bearing slider is threadedly connected to the first air-bearing lead screw. The Y-axis adjustment device includes a second motor, a second air-bearing lead screw, a second air-bearing guide rail, and a second air-bearing slider. The second motor is mounted on the frame, the second air-bearing lead screw is coaxially rotatable with the drive end of the second motor, the second air-bearing guide rail is mounted on the frame and perpendicular to the first air-bearing guide rail, the second air-bearing slider is slidably connected to the second air-bearing guide rail, and the second air-bearing slider is threadedly connected to the second air-bearing lead screw. The mounting platform is mounted on the second air-bearing slider.

9. A method for testing the static performance of gas bearings based on a pre-buoyancy followed by pressure compensation test, characterized in that, A static performance test bench for gas bearings as described in any one of claims 1-8 is adopted, comprising the following steps: controlling a loading device to disengage the floating support plate from the gas bearing under test and setting the force sensor to zero; controlling the loading device to make the lower surface of the floating support plate contact and adhere to the upper surface of the gas bearing under test; performing multiple loading and unloading cycles through the loading device to verify the repeatability of structural deformation; driving the floating support plate to press against the gas bearing under test with a series of loads covering the expected test range through the loading device, and acquiring multiple sets of load and displacement data through the force sensor and displacement measurement unit, and establishing a compensation relationship for the structural deformation of the test bench based on the multiple sets of load and displacement data; supplying gas to the gas bearing under test to make the floating support plate float; applying a test load to the floating support plate through the loading device, and acquiring the load-bearing capacity and displacement measurement values ​​in real time through the force sensor and displacement measurement unit; deriving the corresponding structural deformation of the test bench based on the load-bearing capacity and the compensation relationship, calibrating the displacement measurement value to obtain the actual gas film thickness; analyzing the relationship between the load-bearing capacity and the actual gas film thickness to obtain the static performance parameters of the gas bearing under test.

10. A method for testing the static performance of gas bearings based on a pre-pressure followed by a float test, characterized in that, A static performance test bench for gas bearings as described in any one of claims 1-8 is used, comprising the following steps: controlling a loading device to disengage the floating support plate from the gas bearing under test and setting the force sensor to zero; controlling the loading device to bring the lower surface of the floating support plate into contact with and adhere to the upper surface of the gas bearing under test; performing multiple loading and unloading cycles through the loading device to verify the repeatability of structural deformation; applying a predetermined preload to the floating support plate through the loading device, and setting the reading of the displacement measuring unit to zero while maintaining the preload and ensuring system stability; supplying gas to the gas bearing under test while maintaining the preload; acquiring the bearing force generated by the gas bearing under test through the force sensor and acquiring the displacement of the floating support plate through the displacement measuring unit, wherein the displacement is the actual gas film thickness; analyzing the relationship between the bearing force and the actual gas film thickness to obtain the static performance parameters of the gas bearing under test.

Images