Porous static pressure air floating cushion with adjustable electromagnetic force preload

Abstract

The invention discloses an adjustable electromagnetic force preloading porous static pressure air floating cushion, and belongs to the technical field of air floating transmission, the air floating cushion comprises a base, an air floating cushion main body, an air supply mechanism, an electromagnetic assembly and an adjusting mechanism, the base is provided with a magnetic conductive material layer, and an air floating surface is formed at the top of the base; the air floating cushion main body is provided with a porous throttling block, and an air film gap is formed between the bottom of the air floating cushion main body and the base; the air supply mechanism is communicated with the air floating cushion main body and is used for conveying air to the porous throttling block; the electromagnetic assembly is arranged on the air floating cushion main body and is used for generating adjustable electromagnetic preloading force on the magnetic conductive material layer; the adjusting mechanism is connected to the electromagnetic assembly and used for changing the distance between the electromagnetic assembly and the magnetic conductive material layer so as to adjust the magnitude of the electromagnetic preloading force. Electromagnetic force adjustable preloading, porous uniform throttling and a mechanical fine adjustment mechanism are organically integrated, and the effects of preloading force flexible control, gas film pressure balanced distribution and system rigidity strengthening are synchronously achieved on the premise that external complex equipment is not needed.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of air floating transmission, in particular to an adjustable electromagnetic force preloaded porous static pressure air floating pad. BACKGROUND

[0002] The static pressure air floating technology is a new technology that uses high-pressure gas as lubricating and bearing medium to replace the traditional mechanical contact ball + screw displacement mechanism to realize zero friction, zero pollution, sub-micron or even nanometer level positioning / displacement movement, and is often used as a technical carrier of guide rails, rotary tables or air floating pads.

[0003] The static pressure air floating equipment is generally divided into open structure and closed structure according to the gas support form. The closed structure realizes high stiffness and high stability support characteristics through a closed gas constraint channel, and is often used in guide rail and rotary table systems. However, its structure is complex and requires strict installation space, and cannot be compatible with all application scenarios, and has low adaptability. In contrast, the air floating pad of the open structure is widely used due to its simple design and strong applicability.

[0004] However, for the open structure, when the gas film thickness is too large, the gas flow field is prone to self-excited oscillation phenomenon, which is called air hammer phenomenon. The air hammer phenomenon can cause instability of the support system and cause severe vibration, which seriously affects the accuracy of the equipment. In order to suppress the air hammer phenomenon, external preloading force must be applied to the air floating pad to thin the gas film and increase the stiffness.

[0005] The traditional solution mainly relies on gravity preloading and vacuum preloading. The gravity preloading is to increase the counterweight above the air floating pad to generate downward pressure. This method has a simple structure, but the preloading force cannot be dynamically adjusted, and the additional counterweight occupies space, affecting the integration of the equipment. The vacuum preloading is to set a vacuum cavity at the bottom of the air floating pad to provide preloading by using negative pressure adsorption force. This method needs to rely on an external vacuum pump to maintain negative pressure, and the response speed is slow. Moreover, the vacuum cavity will occupy the effective air floating area, reducing the bearing efficiency.

[0006] In addition, the traditional air floating pad usually uses small hole throttling to control the gas flow, that is, the gas is supplied to the gas film area through discrete small holes. Although this method can realize basic support function, the gas jetted through the small holes is easy to form a local high pressure area in the gas film, which is commonly called air pressure spot, resulting in uneven pressure distribution and nonlinear fluctuation of gas film stiffness, further aggravating the system instability. SUMMARY

[0007] The purpose of the present application is to provide an adjustable electromagnetic force preloaded porous static pressure air floating pad to solve the technical problems of inflexible preloading force adjustment, slow response speed and uneven gas film pressure distribution in the prior art.

[0008] As conceived above, the technical solution adopted by the present application is:

[0009] An adjustable electromagnetic force preloaded porous aerostatic pad, comprising:

[0010] a base provided with a layer of magnetic conductive material, a top of the base forming an aerostatic surface;

[0011] an aerostatic pad body provided with a porous throttle block, a gap between a bottom of the aerostatic pad body and the aerostatic surface forming an air film gap;

[0012] a gas supply mechanism in communication with the aerostatic pad body for supplying gas to the porous throttle block;

[0013] an electromagnetic assembly provided in the aerostatic pad body, the electromagnetic assembly being used to generate an adjustable electromagnetic preloaded force on the layer of magnetic conductive material;

[0014] an adjusting mechanism connected to the electromagnetic assembly for changing a distance between the electromagnetic assembly and the layer of magnetic conductive material to adjust the size of the electromagnetic preloaded force.

[0015] Preferably, a gas supply port is formed on the aerostatic pad body, the gas supply port is in communication with the porous throttle block through a gas supply channel, the gas supply mechanism is capable of supplying gas to the gas supply port, and the gas passes through the gas supply channel and diffuses to the air film gap through the porous throttle block.

[0016] Preferably, the gas supply port is provided on a sidewall of the aerostatic pad body, the gas supply channel includes a main channel parallel to the aerostatic surface and branch channels, the main channel is in communication with the gas supply port, a plurality of branch channels are distributed on both sides of the main channel and are arranged in parallel and spaced apart from the main channel, and the branch channels and the main channel are in communication through auxiliary channels.

[0017] Preferably, the gas supply channel further includes an annular channel provided at the center of the gas supply channel for communicating the main channel, the branch channels and the auxiliary channels.

[0018] Preferably, the porous throttle block is provided in the middle of the aerostatic pad body, a plurality of electromagnetic assemblies are provided, the plurality of electromagnetic assemblies are arranged in a ring and spaced apart from the outer periphery of the porous throttle block, and the electromagnetic assemblies form a magnetic attraction force with the layer of magnetic conductive material on the base after being energized as the electromagnetic preloaded force.

[0019] Preferably, a first groove is formed in the middle of the aerostatic pad body, the porous throttle block is embedded in the first groove, a plurality of second grooves are arranged in the aerostatic pad body in the outer periphery of the first groove, and one of the electromagnetic assemblies is embedded corresponding to each of the second grooves.

[0020] As preferred, a plurality of third grooves are formed on the base, the third grooves correspond to the second grooves one by one, and one layer of the magnetic conductive material is embedded in each third groove, and the layer of the magnetic conductive material is arranged opposite to the corresponding electromagnetic assembly.

[0021] As preferred, the adjusting mechanism is a differential screw mechanism, and the electromagnetic assembly is connected to an output end of the differential screw mechanism.

[0022] As preferred, the pitches of the two screws of the differential screw mechanism are 2 mm and 1 mm respectively.

[0023] As preferred, a monitoring assembly is arranged on the bottom of the air cushion body or the top of the base, and the monitoring assembly is used to monitor the thickness of the air film gap.

[0024] The present application has the following advantages:

[0025] The adjustable electromagnetic force preloaded porous static pressure air cushion provided by the present application can first generate an adjustable electromagnetic preloading force on the magnetic conductive material layer on the top of the base through the electromagnetic assembly, and compared with the traditional gravity preloading which cannot dynamically adjust the preloading force, the design can flexibly adjust the preloading force according to actual requirements, improves the flexibility of preloading force adjustment, and meets the requirements of the air cushion preloading force under different working conditions. Moreover, the electromagnetic assembly responds quickly and can quickly adjust the electromagnetic preloading force according to the working condition change, effectively improves the response speed of the system. In addition, the porous throttle block is arranged at the bottom of the air cushion body, compared with the traditional small hole throttling mode, the porous throttle block can make the gas provided by the gas supply mechanism enter the air film gap more uniformly, avoid the formation of local high pressure area, i.e. air pressure spot, in the air film after the gas is injected through the small hole, thereby improving the uneven air film pressure distribution, making the air film pressure distribution more uniform, enhancing the stability of the air film stiffness, and further improving the stability and precision of the whole air cushion system. The adjusting mechanism adjusts the electromagnetic preloading force by changing the distance between the electromagnetic assembly and the magnetic conductive material layer, which provides a convenient and effective way for preloading force adjustment, so that the operator can realize accurate adjustment of the electromagnetic preloading force according to actual work requirements, optimize the performance of the air cushion in all directions, and solve the technical problems of inflexible preloading force adjustment, slow response speed and uneven air film pressure distribution in the prior art. In summary, the present application organically integrates the electromagnetic force adjustable preloading, the porous uniform throttling and the mechanical fine adjustment mechanism, and simultaneously achieves the effects of flexible preloading force control, uniform air film pressure distribution and system stiffness enhancement without the need of external complex equipment. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 Fig. 1 is a first cross-sectional view of the adjustable electromagnetic force preloaded porous static pressure air cushion provided by the embodiment of the present application;

[0027] Figure 2 is a structural schematic diagram of the adjustable electromagnetic force preloaded porous static pressure air floating pad provided by the embodiment of the present application;

[0028] Figure 3 is a first simulation diagram of the throttling hole fluid of the traditional small hole throttling material;

[0029] Figure 4 is a second simulation diagram of the throttling hole fluid of the traditional small hole throttling material;

[0030] Figure 5 is a simulation diagram of the magnetic flux density distribution of the ferromagnetic material and the magnet without gap;

[0031] Figure 6 is a simulation diagram of the magnetic flux density distribution of the ferromagnetic material and the magnet with a gap of 0.5mm;

[0032] Figure 7 is a simulation diagram of the magnetic flux density distribution of the ferromagnetic material and the magnet with a gap of 1mm;

[0033] Figure 8 is a simulation diagram of the magnetic flux density distribution of the ferromagnetic material and the magnet with a gap of 2mm;

[0034] Figure 9 is a relationship curve diagram of the air film thickness and the load capacity of the air floating pad;

[0035] Figure 10 is a relationship curve diagram of the air film thickness and the stiffness of the air floating pad;

[0036] Figure 11 is a second sectional view of the adjustable electromagnetic force preloaded porous static pressure air floating pad provided by the embodiment of the present application;

[0037] Figure 12 is a third sectional view of the adjustable electromagnetic force preloaded porous static pressure air floating pad provided by the embodiment of the present application.

[0038] In the figure:

[0039] 1, base; 10, air floating surface; 11, magnetic conductive material layer; 12, third groove;

[0040] 2, air floating pad main body; 20, air film gap; 21, porous throttling block; 22, air supply port; 23, air supply channel; 231, main channel; 232, branch channel; 233, auxiliary channel; 234, annular channel; 24, first groove; 25, second groove;

[0041] 3, electromagnetic assembly; 4, adjusting mechanism. DETAILED DESCRIPTION

[0042] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like reference numerals are used throughout the drawing figures to refer to the same or like elements or elements having the same or similar functionality. The following detailed description is exemplary in nature and is intended to provide a thorough description of the natural application and is not intended to limit the application as it is to be defined by the appended claims.

[0043] In the description of the present application, unless otherwise clearly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrated; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0044] In the present application, unless otherwise clearly specified and limited, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "above" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the horizontal height of the first feature is higher than that of the second feature. The first feature "below", "below" and "below" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the horizontal height of the first feature is less than that of the second feature.

[0045] The technical solutions of the present application are further illustrated below in conjunction with the drawings and through specific embodiments.

[0046] Reference Figure 1 and Figure 2 The adjustable electromagnetic force preloaded porous static pressure air cushion provided by the embodiments of the present application includes a base 1, an air cushion body 2, a gas supply mechanism, an electromagnetic assembly 3 and an adjusting mechanism 4. Wherein, the base 1 is provided with a magnetic conductive material layer 11, and the top of the base 1 forms an air floating surface 10; the air cushion body 2 is provided with a porous throttle block 21, and the bottom of the air cushion body 2 and the air floating surface 10 form an air film gap 20; the gas supply mechanism is communicated with the air cushion body 2, and is used for delivering gas to the porous throttle block 21; the electromagnetic assembly 3 is arranged on the air cushion body 2, and is used for generating an adjustable electromagnetic preload force on the magnetic conductive material layer 11; the adjusting mechanism 4 is connected to the electromagnetic assembly 3, and is used for changing the distance between the electromagnetic assembly 3 and the magnetic conductive material layer 11 to adjust the size of the electromagnetic preload force.

[0047] The adjustable electromagnetic force preloading porous static pressure air floating pad provided by the application can first generate an adjustable electromagnetic preloading force on the magnetic material layer 11 on the top of the base 1 through the electromagnetic assembly 3. Compared with the traditional gravity preloading which cannot dynamically adjust the preloading force, the design can flexibly adjust the preloading force according to actual requirements, improves the flexibility of preloading force adjustment, and meets the requirements of the air floating pad preloading force under different working conditions. Moreover, the electromagnetic assembly 3 responds quickly and can quickly adjust the electromagnetic preloading force according to the working condition change, effectively improving the response speed of the system. In addition, the porous throttling block 21 is arranged at the bottom of the air floating pad main body 2. Compared with the traditional small hole throttling mode, the porous throttling block 21 can make the gas provided by the gas supply mechanism enter the gas film gap 20 more uniformly, avoid the formation of a local high pressure area, i.e., a gas pressure spot, in the gas film after the gas is injected through the small hole, thereby improving the uneven gas film pressure distribution, making the gas film pressure distribution more uniform, enhancing the stability of the gas film stiffness, and further improving the stability and precision of the entire air floating pad system. The adjusting mechanism 4 adjusts the electromagnetic preloading force by changing the distance between the electromagnetic assembly 3 and the magnetic material layer 11, which provides a convenient and effective way for preloading force adjustment, so that the operator can accurately adjust the electromagnetic preloading force according to actual work needs, optimize the performance of the air floating pad in all directions, and solve the technical problems of the existing air floating pad, such as inflexible preloading force adjustment, slow response speed, and uneven gas film pressure distribution. In summary, the application organically integrates the electromagnetic force adjustable preloading, the porous uniform throttling, and the mechanical fine adjustment mechanism, and simultaneously achieves the effects of flexible preloading force control, uniform gas film pressure distribution, and system stiffness enhancement without the need for external complex equipment.

[0048] The specific structure and working principle of the adjustable electromagnetic force preloading porous static pressure air floating pad will be described in detail below.

[0049] The air floating pad main body 2 is provided with a porous throttling block 21, and the air floating pad main body 2 and the base 1 form a gas film gap 20 at the bottom. In use, the gas supply mechanism delivers gas to the porous throttling block 21, thereby diffusing the gas to the gas film gap 20. The advantage of throttling operation through the porous throttling block 21 over the traditional small hole throttling is that the porous throttling block 21 realizes continuous and diffused seepage of the gas through the uniformly distributed micron-level pores, thereby suppressing the generation of vortex.

[0050] As shown in Figure 3 , the traditional small hole throttling causes the gas to be injected at a local high pressure due to the discrete hole structure, forming turbulence and vortex, which not only destroys the stability of the gas film but also causes pressure pulsation and vibration.

[0051] As shown in Figure 4The micro-porous structure of the porous throttling block 21 allows the gas to permeate in the form of low-speed, uniformly distributed laminar flow, effectively attenuates the kinetic energy of the gas through viscous dissipation and porous medium resistance, avoids the release of concentrated energy, thereby greatly reduces the intensity of the vortex, makes the gas film pressure distribution more uniform, and improves the dynamic stability of the bearing.

[0052] The porous throttling block 21 can be made of porous graphite, porous ceramic, or sintered metal porous material, without limitation.

[0053] Specifically, the porous throttling block 21 is arranged in the middle of the air cushion pad body 2, and the electromagnetic assembly 3 is arranged in multiple, multiple electromagnetic assemblies 3 are arranged around and spaced apart on the outer periphery of the porous throttling block 21, and the electromagnetic assembly 3 forms a magnetic attraction force with the magnetic conductive material layer 11 on the base 1 after being energized as an electromagnetic preload. The porous throttling block 21 is located in the middle, which can make the gas delivered from the gas supply mechanism diffuse to the surrounding in a more symmetrical and uniform manner, thereby forming a more uniform and stable gas film between the bottom of the air cushion pad body 2 and the base 1, effectively avoiding the abnormal local pressure in the gas film, further optimizing the gas film pressure distribution, and improving the stability and bearing precision of the air cushion pad as a whole. Multiple electromagnetic assemblies 3 are arranged around and spaced apart on the outer periphery of the porous throttling block 21, which can exert a magnetic attraction force, i.e. an electromagnetic preload, on the magnetic conductive material layer 11 on the base 1 from multiple directions. Such a layout makes the preload distribution more uniform, avoids uneven stress on the air cushion pad and local deformation due to the concentration of the preload in a certain place, ensures that the air cushion pad can obtain stable and balanced support in all directions, and enhances the adaptability and stability of the air cushion pad under complex working conditions.

[0054] The electromagnetic assembly 3 can be selected from an electromagnet, an electromagnetic coil, or a hybrid of permanent magnet and electromagnet, without limitation.

[0055] More specifically, a first groove 24 is formed in the middle of the air cushion pad body 2, the porous throttling block 21 is embedded in the first groove 24, and part of the porous throttling block 21 protrudes downward from the bottom of the air cushion pad body 2; a plurality of second grooves 25 are arranged on the air cushion pad body 2 along the outer periphery of the first groove 24, and one electromagnetic assembly 3 is embedded in each second groove 25. The first groove 24 provides precise positioning for the porous throttling block 21, ensures stable installation, and prevents the porous throttling block 21 from moving randomly during work, thereby ensuring the stability and consistency of gas throttling and distribution, optimizing gas film formation and pressure distribution, and improving the bearing performance and stability of the air cushion pad.

[0056] The second groove 25 provides an accurate installation position for the electromagnetic assembly 3, ensures the accuracy of the surrounding layout of multiple electromagnetic assemblies 3, makes the electromagnetic preload force exerted by them on the magnetic material layer 11 more uniform and symmetrical, and avoids uneven stress on the air cushion caused by the positional deviation of the electromagnetic assembly 3. The groove type installation method can also effectively protect the electromagnetic assembly 3, reduce the interference and damage risk of external factors, prolong the service life of the electromagnetic assembly 3, and ensure the long-term stable operation of the entire adjustable electromagnetic force preloaded porous static pressure air cushion system.

[0057] Further, a plurality of third grooves 12 are formed in the base 1, and each third groove 12 corresponds to a second groove 25. A magnetic material layer 11 is embedded in each third groove 12, and the magnetic material layer 11 is arranged opposite to the corresponding electromagnetic assembly 3. This one-to-one correspondence arrangement can make the electromagnetic force generated by each electromagnetic assembly 3 more effectively act on the corresponding magnetic material layer 11, enhance the coupling efficiency of the magnetic attraction force between the electromagnetic assembly 3 and the magnetic material layer 11, and further improve the effect of the electromagnetic preload, so that the preload on the air cushion is more accurately controllable, effectively improving the stability and bearing precision of the air cushion. Through the arrangement of the third groove 12, the magnetic material layer 11 is well positioned and fixed, ensuring the accuracy and stability of the position of the magnetic material layer 11 during operation.

[0058] In summary, in this embodiment, the electromagnetic assembly 3 and the porous choke block 21 are built into the air cushion body 2, and the magnetic material layer 11 is integrated into the base 1, which optimizes the overall structural layout of the air cushion. The close combination of various key components reduces the external space occupation of the air cushion, making the structure more compact, which is conducive to the installation and integration of the air cushion in different equipment, especially in application scenarios with strict space requirements, which can better adapt to limited installation space and improve the overall space utilization of the equipment.

[0059] Optionally, a monitoring assembly is arranged on the bottom of the air cushion body 2 or the top of the base 1, and the monitoring assembly is used to monitor the thickness of the air film gap 20. By monitoring the thickness of the air film gap 20 in real time, abnormal changes in the thickness of the air film can be found in time. When the air film thickness approaches the critical value that may cause air hammer phenomenon or lead to instability of the support system, the electromagnetic preload or gas supply parameters can be quickly adjusted according to the monitoring data to prevent the air cushion from vibrating violently, the precision from decreasing, and other problems caused by improper air film thickness, and to maintain the stable operation of the air cushion. In addition, accurate control of the thickness of the air film gap 20 helps to achieve more accurate positioning and displacement movement of the air cushion. In the air floating transmission application scenario with extremely high precision requirements, the air film thickness data fed back by the monitoring assembly can be used to adjust the relevant parameters in real time to ensure that the air cushion always works in the ideal air film thickness state, thereby significantly improving the positioning and displacement precision of the air cushion.

[0060] Among them, the monitoring assembly can be selected from infrared sensors, laser sensors or capacitive sensors, etc., which will not be described here.

[0061] Optionally, the base 1 is made of marble material. Marble has very high hardness and good wear resistance, which enables the base 1 to withstand various pressures and friction generated during the working process of the air cushion, and is not prone to wear, deformation and other problems. Moreover, marble is a non-magnetic material, which makes it not interfere with the magnetic field generated between the electromagnetic assembly 3 and the magnetic material layer 11, and can maintain the purity and stability of the magnetic field between the electromagnetic assembly 3 and the magnetic material layer 11, ensuring the precise control of the electromagnetic preload.

[0062] In other embodiments, the base 1 can also be made of granite, aluminum alloy or steel, etc., which will not be limited here.

[0063] The base 1 is provided with a magnetic material layer 11. After the electromagnetic assembly 3 is powered on, it forms a magnetic attraction force with the magnetic material layer 11 on the base 1 as the electromagnetic preload. In this embodiment, the magnetic material layer 11 is made of 1j22 ferromagnetic material.

[0064] The magnetic flux density mode in the ferromagnetic material at different distances between the single-piece magnet and the ferromagnetic material.

[0065] Figure 5 The magnetic flux density distribution of the ferromagnetic material and the magnet without gap, Figure 6 The magnetic flux density distribution of the ferromagnetic material and the magnet with a distance of 0.5mm. Figure 7 The magnetic flux density distribution of the ferromagnetic material and the magnet with a distance of 1mm, Figure 8 The magnetic flux density distribution of the ferromagnetic material and the magnet with a distance of 2mm. The simulation analysis result shows that as long as the magnetic flux density of the permanent magnet in the ferromagnetic material presents a fan-shaped distribution with the lowest point saturated within the magnet material, the stability of the magnetic flux density mode in the magnetic force can be met. By controlling the distance between the ferromagnetic material and the magnet, according to the magnetic force calculation formula:

[0066]

[0067] Among them, μ r is the relative magnetic permeability of the ferromagnetic material, μ0 is the vacuum permeability, S is the magnetic field and the ferromagnetic material acting surface area mm 2 , B is the magnetic flux density of the magnetic field and the material acting surface.

[0068] The magnetic force is the relative magnetic permeability μ r, the magnetic field, the surface area S of the ferromagnetic material and the magnetic flux density B at the surface of the ferromagnetic material jointly determine the magnetic force. When the cross-sectional area of the magnet and the magnetic permeability of the magnetic characteristic layer of the ferromagnetic material are fixed, the magnetic force is mainly determined by the magnetic flux density on the surface of the ferromagnetic material, and the magnetic flux density is determined by the magnetic field distribution of the magnet. The smaller the distance, the greater the magnetic flux density.

[0069] The adjusting mechanism 4 is connected to the electromagnetic assembly 3, and is used to change the distance between the electromagnetic assembly 3 and the magnetic conductive material layer 11 to adjust the size of the electromagnetic preload.

[0070] Specifically, the adjusting mechanism 4 is a differential screw mechanism, and the electromagnetic assembly 3 is connected to the output end of the differential screw mechanism. The differential screw mechanism can realize high-precision micro-displacement adjustment. The extremely small and accurate displacement change of the electromagnetic assembly 3 is generated by rotary driving, and the high-precision displacement adjustment is directly related to the accurate change of the distance between the electromagnetic assembly 3 and the magnetic conductive material layer 11. Moreover, the differential screw mechanism relies on rotary driving, and the operation is relatively simple. Compared with some complex adjustment methods, the operator only needs to rotate to realize the displacement adjustment of the electromagnetic assembly 3, which not only reduces the operation difficulty, but also improves the adjustment efficiency. In actual application scenarios, the worker can more quickly adjust the electromagnetic preload according to the working condition, thereby improving the response speed of the air cushion pad under different working conditions. In addition, the differential screw mechanism itself has a compact structure and high stability. The compact structure is conducive to reasonable layout in the limited space of the air cushion pad, reduces the occupation of the space of other components, and improves the integration of the overall structure of the air cushion pad.

[0071] More specifically, the differential screw mechanism is composed of two screws with different leads, and the output displacement of the screw is smaller than the single-lead displacement when the screw is rotated. When the screw is rotated, the two screws with different leads generate a displacement difference, so that the output displacement is smaller than the displacement of the single-lead screw. Through the rotation action, the micrometer-level linear displacement of the electromagnetic assembly 3 is converted, and the distance between the electromagnetic assembly 3 and the magnetic layer can be accurately controlled only by manual adjustment, thereby realizing fine adjustment of the preload. Compared with the traditional single-lead screw mechanism, the displacement resolution is improved by more than ten times under the same operation amplitude, which completely solves the technical bottleneck of the gravity preload that cannot be finely adjusted and the response lag of the vacuum preload, and provides a reliable manual fine control means for dynamic optimization of the air film thickness.

[0072] Alternatively, the leads of the two screws of the differential screw mechanism are 2 mm and 1 mm, respectively.

[0073] In other embodiments, the adjusting mechanism 4 can also be selected from a piezoelectric ceramic driving mechanism, an electric push rod mechanism or a hydraulic adjusting mechanism 4, and the like, which will not be described here.

[0074] The differential screw structure is used to realize the micro-displacement generated by the rotation of the knob. According to the differential screw displacement calculation formula:

[0075] L = N(Ph1 ± Ph2)

[0076] Wherein: L is the actual displacement distance of the activity nut, N is the number of screw rotation, Ph1 is the lead of one of the screw, Ph2 is the lead of another screw. As long as the difference between the lead of two screws is within 1mm, the resolution of 1 micron displacement can be achieved by rotating the knob.

[0077] The throttling effect and pressure distribution of the porous metal material are stronger than that of small hole throttling, the excellent gas film uniformity avoids the "gas pressure spot" of the traditional small hole throttling, and at the same time, the uniformity of the magnetic field can obtain higher carrying capacity and stiffness under the same gas film thickness, and maintain higher gas film stability.

[0078] Referring to Figure 9 and Figure 10 , by applying the electromagnetic preloading porous throttling method to the air floating block, and through simulation analysis, the feasibility of micron-level control of the gas film of the magnetic force preloading air floating block is verified. The results show that the theoretical curve and the test curve are highly consistent in the two groups of tests, and there is a certain difference between the theoretical magnetic force and the test value, but the error does not exceed 10%. Through the differential screw adjustment gap, the error can realize micron-level control of the thickness of the gas film.

[0079] The gas supply mechanism is in communication with the air floating pad main body 2, and is used for conveying gas to the porous throttling block 21. Among them, the gas supply mechanism can be selected from air compressor, high pressure gas cylinder gas supply system, etc., which is not limited here.

[0080] Referring to Figure 11 and Figure 12The air supply port 22 is arranged on the side wall of the air cushion main body 2, and the air supply channel 23 includes a main channel 231 parallel to the air floating surface 10 and branch channels 232. The main channel 231 is connected to the air supply port 22, and a plurality of branch channels 232 are arranged on both sides of the main channel 231 in parallel and at intervals. The branch channels 232 and the main channel 231 are connected through auxiliary channels 233. The air supply port 22 is arranged on the side wall, which facilitates the connection of the air supply mechanism, optimizes the overall layout of the air cushion, reduces the occupation of the space on the top or bottom of the air cushion, and makes the air cushion more flexible during installation and integration. The main channel 231 is arranged in parallel to the air floating surface 10, which can uniformly distribute the gas in the direction parallel to the air floating surface 10 and provide a more balanced gas supply basis for the air film. The plurality of branch channels 232 are arranged on both sides of the main channel 231 in parallel and at intervals, which further refines the gas delivery path and allows the gas to cover the bottom of the air cushion more uniformly, helping to form a more uniform and stable air film and effectively avoiding excessive differences in local gas pressure in the air film, thereby improving the load stability and precision of the air cushion.

[0081] Further, the air supply port 22 is arranged on the side wall of the air cushion main body 2, and the air supply channel 23 includes a main channel 231 parallel to the air floating surface 10 and branch channels 232. The main channel 231 is connected to the air supply port 22, and a plurality of branch channels 232 are arranged on both sides of the main channel 231 in parallel and at intervals. The branch channels 232 and the main channel 231 are connected through auxiliary channels 233. The air supply port 22 is arranged on the side wall, which facilitates the connection of the air supply mechanism, optimizes the overall layout of the air cushion, reduces the occupation of the space on the top or bottom of the air cushion, and makes the air cushion more flexible during installation and integration. The main channel 231 is arranged in parallel to the air floating surface 10, which can uniformly distribute the gas in the direction parallel to the air floating surface 10 and provide a more balanced gas supply basis for the air film. The plurality of branch channels 232 are arranged on both sides of the main channel 231 in parallel and at intervals, which further refines the gas delivery path and allows the gas to cover the bottom of the air cushion more uniformly, helping to form a more uniform and stable air film and effectively avoiding excessive differences in local gas pressure in the air film, thereby improving the load stability and precision of the air cushion.

[0082] Further, the gas supply channel 23 further comprises an annular channel 234 arranged in the center of the gas supply channel 23 for connecting the main channel 231, the branch channel 232 and the auxiliary channel 233. The annular channel 234 functions as a gas pressure equalizer. It integrates the gas from the main channel 231, the branch channel 232 and the auxiliary channel 233, and makes the gas from different paths intermingle in the annular channel 234, balances the gas pressure at different places, ensures that the gas pressure diffused from the porous throttle block 21 to the gas film gap 20 is more uniform, improves the stability of the gas film, reduces the pressure fluctuation of the gas film, effectively avoids the vibration or instability phenomenon of the air cushion caused by uneven pressure, and thus improves the operation accuracy of the air cushion. In addition, the annular channel 234 enhances the overall connectivity and redundancy of the gas supply channel 23. When a local channel is slightly blocked or the gas flow is not smooth, the gas can flow through other paths through the annular channel 234, ensuring the continuity of the air cushion gas supply, reducing the risk of performance degradation or even failure of the air cushion caused by local failure, and improving the reliability of the air cushion operation.

[0083] The above embodiments only illustrate the basic principles and characteristics of the present application, and the present application is not limited to the above embodiments. Various changes and modifications can be made without departing from the spirit and scope of the present application, and these changes and modifications all fall within the scope of the present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. A porous static pressure air flotation cushion with adjustable electromagnetic force preload, characterized in that: include: A base (1) is provided with a magnetic conductive material layer (11), and an air bearing surface (10) is formed on the top of the base (1); The air flotation cushion body (2) is provided with a porous throttling block (21), and an air film gap (20) is formed between the bottom of the air flotation cushion body (2) and the air flotation surface (10); An air supply mechanism, connected to the air floating cushion body (2), for delivering gas to the porous throttling block (21); An electromagnetic component (3) is arranged on the air-floating cushion body (2), and the electromagnetic component (3) is used to generate an adjustable electromagnetic preload force on the magnetic conductive material layer (11); An adjusting mechanism (4) is connected to the electromagnetic component (3) and is used to change the distance between the electromagnetic component (3) and the magnetic conductive material layer (11) to adjust the magnitude of the electromagnetic preload force.

2. The adjustable electromagnetic force preload porous static pressure air flotation cushion according to claim 1, characterized in that: An air supply port (22) is formed on the air floating cushion body (2), and the air supply port (22) is connected to the porous throttling block (21) through an air supply channel (23). The air supply mechanism can supply air to the air supply port (22), and the gas passes through the air supply channel (23) and diffuses through the porous throttling block (21) to the air film gap (20).

3. The adjustable electromagnetic force preload porous static pressure air floating cushion according to claim 2, characterized in that: The air supply port (22) is arranged on the side wall of the air flotation cushion body (2); the air supply channel (23) comprises a main channel (231) and a branch channel (232) parallel to the air flotation surface (10); the main channel (231) is connected to the air supply port (22); a plurality of branch channels (232) are distributed on both sides of the main channel (231) and are arranged parallel to and spaced from the main channel (231); the branch channels (232) and the main channel (231) are connected via an auxiliary channel (233).

4. The adjustable electromagnetic force preload porous static pressure air floating cushion according to claim 3, characterized in that: The air supply channel (23) further comprises an annular channel (234), which is arranged at the center of the air supply channel (23) and is used to connect the main channel (231), the branch channel (232) and the auxiliary channel (233).

5. The adjustable electromagnetic force preload porous static pressure air floating cushion according to claim 1, characterized in that: The porous throttling block (21) is arranged in the middle of the air floating cushion body (2); a plurality of electromagnetic components (3) are provided, and the plurality of electromagnetic components (3) are arranged around and at intervals on the outer periphery of the porous throttling block (21); when the electromagnetic components (3) are energized, they form a magnetic attraction force with the magnetic conductive material layer (11) on the base (1) as the electromagnetic preload force.

6. The adjustable electromagnetic force preload porous static pressure air floating cushion according to claim 5, characterized in that: A first groove (24) is provided in the middle of the air-floating cushion body (2), and the porous throttling block (21) is embedded in the first groove (24); a plurality of second grooves (25) are provided on the air-floating cushion body (2) at intervals along the outer periphery of the first groove (24), and one of the electromagnetic components (3) is embedded in each of the second grooves (25).

7. The adjustable electromagnetic force preload porous static pressure air floating cushion according to claim 6, characterized in that: The base (1) is provided with a plurality of third grooves (12), the third grooves (12) corresponding to the second grooves (25) one by one, and a magnetic conductive material layer (11) is embedded in each of the third grooves (12), and the magnetic conductive material layer (11) is arranged relative to the corresponding electromagnetic component (3).

8. The porous static pressure air cushion with adjustable electromagnetic force preload according to claim 1, characterized in that: The regulating mechanism (4) is a differential thread mechanism, and the electromagnetic component (3) is connected to the output end of the differential thread mechanism.

9. The adjustable electromagnetic force preload porous static pressure air flotation cushion according to claim 8, characterized in that: The leads of the two screws on the twin screws of the differential screw mechanism are 2 mm and 1 mm respectively.

10. The porous static pressure air cushion with adjustable electromagnetic force preload according to claim 1, characterized in that: A monitoring component is provided at the bottom of the air-floating cushion body (2) or the top of the base (1), and the monitoring component is used to monitor the thickness of the air film gap (20).

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