Air floating guide rail and manufacturing method

Abstract

The invention belongs to the technical field of precision equipment, and discloses an air floating guide rail and a manufacturing method.The air floating guide rail comprises a guide rail body and a moving platform in sliding fit with the guide rail body through an air film, and the moving platform comprises a plurality of porous material air floating plates fixed together; the porous material air floating plate comprises a granite base, a supporting seat fixed in the granite base, and a porous material plate fixedly connected with the lower end surface of the supporting seat; the shape memory alloy material is used for dynamically controlling the air supply pressure of the small-hole throttler and the micropore flow capacity of the porous material plate, and the double adjusting effects of dynamic adjustment of the small-hole throttler and dynamic ventilation adjustment of the porous material plate are overlaid, so that the inherent material characteristic defect of a traditional porous air foot is overcome; compared with a traditional regulating valve scheme, the device cost is greatly reduced, the device is particularly suitable for being applied to large-size and medium-high-precision air floating platforms, and the operation precision and efficiency of the device are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of precision equipment, and relates to a gas-float guide rail and a manufacturing method. BACKGROUND

[0002] The gas-float guide rail is widely used in the field of precision equipment with high precision and cleanliness due to its zero friction, no wear and high precision. The main components of the gas-float guide rail include a guide rail and a moving platform, also known as a slider or a slide plate. The moving platform is separated from the guide rail by a gas film to realize smooth movement without friction. The gas foot is a key component in the gas-float system of the moving platform. The gas foot introduces compressed air into the air cavity through the air inlet, and adjusts the compressed air through the throttle to uniformly spray the compressed air from the small holes at the bottom or side of the gas foot, thereby forming a thin gas film between the moving platform and the guide rail. The gas foot is divided into a porous gas foot, a small hole throttle gas foot or a groove type gas foot. The porous gas foot realizes uniform gas distribution by virtue of the micro-porous structure and is applied in precision gas-float supports, such as a workpiece table of a lithography machine and an ultra-precision guide rail.

[0003] The porous gas foot has the following deficiencies due to material characteristics: the gas outlet uniformity of the porous gas foot completely depends on the distribution density and aperture consistency of the internal micro-pores. The existing manufacturing process cannot realize an absolutely uniform micro-porous structure. The local micro-porous dense area is prone to have “excessive gas outlet”, which causes the local pressure of the gas film to be too high and causes the supporting platform to vibrate slightly. The micro-porous sparse area may form a “low pressure area” due to insufficient gas outlet, which causes the thickness of the gas film to be uneven and affects the flatness accuracy of the load. This non-uniformity is more prominent in large-size gas feet, which limits the application of the porous gas foot in large-area support scenarios. Therefore, a large-size moving platform needs to increase the number of gas feet to avoid the gas film being uneven due to too large a span. However, the increase in the number of gas feet leads to complex gas paths and a sharp increase in cost. Each additional gas foot needs to be independently or grouped supplied with air, which causes the number of gas path pipelines, sensors and valve components to increase exponentially. For example, a workpiece table of a lithography machine uses 20 gas feet, which need to be matched with 20 high-precision pressure regulating valves. This causes difficulties in equipment maintenance and collaborative control of multiple gas feet and also causes systematic errors. How to match materials, optimize structures and control compensation to realize the application value of the porous material in the medium and high-precision gas-float system, especially in the application of large-size platforms, has become a technical problem to be solved by technical personnel in the field, that is, to control the cost and improve the accuracy through reasonable structural design. SUMMARY

[0004] To solve the technical problems of the porous gas foot in the prior art described in the background, such as the local pressure of the gas film being too high, the thickness of the gas film being uneven, the supporting platform vibrating slightly, the flatness accuracy of the load being affected, the cost of the porous gas foot being high in the application of large-size moving platforms, the maintenance and collaborative control being difficult, and the systematic error being large, the present application provides a gas-float guide rail and a manufacturing method.

[0005] The present application is to solve the above technical problems by the following technical scheme, provide a kind of air floatation guide rail, the air floatation guide rail includes guide rail, and with the guide rail by air film sliding fit mobile platform, the mobile platform includes several fixed together porous material air floatation plate;The porous material air floatation plate includes granite pedestal, support seat fixed in granite pedestal, and the porous material plate of lower end surface fixed connection of support seat, the support seat is provided with air inlet channel, and at least one with the air inlet channel interpenetration throttle channel, the inside of the throttle channel is installed with the pinhole throttler extending to the lower end surface of support seat;Groove is opened in the lower end surface of the support seat, to form air cavity between the lower end surface of the support seat and the upper surface of the porous material plate;The pinhole throttler includes throttler tube base, the center hole of throttler tube base is communicated with throttle channel, shape memory alloy ring is arranged in the center hole, and the shape memory alloy ring is connected with controller and power supply;First air pressure sensor is installed in the inside of throttler tube base, and the first air pressure sensor is electrically connected with controller, and the gas pressure parameter in air cavity is transmitted to controller;The lower surface of the porous material plate is used as working surface and forms air film between guide rail.

[0006] Further, the cross section of the guide rail is rectangular, and the number of the corresponding porous material air floatation plate is four. The four porous material air floatation plates are fixedly connected and surround the periphery of the guide rail. Air films are formed between the four working surfaces of the four porous material air floatation plates and the four surfaces of the guide rail, so that the mobile platform composed of the four porous material air floatation plates is suspended on the guide rail.

[0007] Further, the lower part of the guide rail is further provided with a guide rail support.

[0008] Further, the material of the shape memory alloy ring is NiTi alloy.

[0009] Further, a limiting stop ring is further arranged in the center hole above the shape memory alloy ring.

[0010] Further, the center hole of the throttler tube base is in a stepped shape, the bottom part has a chamfer, the middle part has a shape memory alloy ring mounting groove and a limiting stop ring mounting groove from bottom to top, respectively, a first air pressure sensor seat hole is further arranged in the throttler tube base in parallel with the center hole, a threading hole is arranged on the side surface of the throttler tube base and communicates with the center hole and the first air pressure sensor seat hole, the outer end of the threading hole is connected with a first special-shaped plug with a through hole through internal threads, the first air pressure sensor is installed in the first air pressure sensor seat hole, the data line of the first air pressure sensor passes through the through hole of the first special-shaped plug, and a first O-shaped sealing ring is further arranged between the bottom part of the first special-shaped plug and the data line of the first air pressure sensor.

[0011] Further, the depth of the groove arranged on the lower end surface of the support base is 0.5-2mm.

[0012] Further, the material of the porous material plate is one of sintered graphite, porous alumina, porous silicon carbide, or porous silicon nitride.

[0013] Further, the porous material plate is a combined structure of shape memory alloy wires embedded in porous ceramics; the shape memory alloy wires are embedded in the surface layer of the upper surface of the porous material plate to a depth of 0.1-0.2mm, and the shape memory alloy wires are uniformly distributed radially along the geometric center of the porous material plate to the edge, with an included angle of 15°-30° between adjacent two shape memory alloy wires; the connecting wires of the shape memory alloy wires are connected to the controller and the power supply after passing through the small hole restrictor.

[0014] Further, the diameter of the shape memory alloy wires decreases uniformly from the center to the edge.

[0015] Further, the material of the shape memory alloy wires is NiTiCu alloy.

[0016] Further, the surface of the shape memory alloy wires is plated with an Al2O3 insulating layer with a thickness of 0.01mm.

[0017] Further, the inlet of each air inlet channel is provided with a special combination joint through screwing, the other end of the special combination joint is connected to the air compressor; a second air pressure sensor is arranged in the special combination joint, the second air pressure sensor is electrically connected to the controller, and the controller is electrically connected to the air compressor and the adjusting valve assembly arranged between the special combination joint and the air compressor.

[0018] Further, the special combination joint comprises a joint base and a fish scale thread head, the thread head end of the fish scale thread head is connected to the inner thread hole of the joint base, the end of the fish scale thread head with fish scales is connected to the branch pipeline, and the joint base is connected to the air inlet channel of the support base through external threads; the joint base comprises an inner hexagonal mounting hole, an internal threaded through hole connected to the inner hexagonal mounting hole, a second air pressure sensor seat hole parallel to the internal threaded through hole, and an air pressure test hole connecting the internal threaded through hole and the second air pressure sensor seat hole, the outer port of the second air pressure sensor seat hole is connected to the second special-shaped plug with a through hole through internal threads, the second special-shaped plug seals the outer port of the second air pressure sensor seat hole, the second air pressure sensor is arranged in the second air pressure sensor seat hole, the data line of the second air pressure sensor passes through the through hole of the second special-shaped plug, and a second O-shaped sealing ring is further arranged between the bottom of the second special-shaped plug and the data line of the second air pressure sensor, and the outer port of the air pressure test hole is sealed through a general plug.

[0019] Further, the air inlet channel is communicated with a plurality of throttling channels, the plurality of throttling channels are uniformly distributed on the support seat in a circular or square matrix, and a small hole throttler is arranged in each throttling channel; a sealing spacer ring is further arranged in the groove, the upper end surface of the sealing spacer ring is tightly attached to and fixed with the lower end surface of the support seat, the lower end surface of the sealing spacer ring is tightly attached to the upper surface of the porous material plate, and the sealing spacer ring seals and separates the air cavity into a plurality of areas, so that the corresponding porous material plate in each area is independently supplied with air by the small hole throttler in the area.

[0020] The application further provides a gas-float guide rail manufacturing method, comprising the following steps: Step one, material selection and blank preparation, the granite base on the guide rail and the porous material plate are all made of granite, the support block is made of carbon fiber reinforced resin, and the porous material plate is made of aluminum oxide; ceramic green body preparation of the porous material plate, mixing aluminum oxide powder and a binder, molding into a green body with embedded holes, threading the pre-stretched shape memory alloy wire into the green body holes according to the designed path, fixing the two ends, and sintering at high temperature to densify the ceramic and form mechanical engagement between the shape memory alloy wire and the ceramic; Step two, rough machining and stress relief, removing most of the excess of the granite guide rail to process the basic structure of the guide rail surface; rough grinding the granite base, the support seat and the blank surface of the porous material plate with a diamond milling cutter or a grinding wheel to remove surface defects such as scratches and pores; the porous material plate needs annealing treatment after rough machining to remove machining stress; Step three, semi-finishing, semi-finishing the granite guide rail, the granite base, the support seat and the porous material plate with a diamond grinding wheel to reach the surface roughness standard, and the granite base and the support seat are machined to form mounting holes at the same time; the groove for storing gas on the support seat is milled by a numerical control milling machine to ensure the contour accuracy; the gas hole pre-drilling guide hole of the support seat avoids position deviation in subsequent precise punching; Step four, finishing, finishing the granite guide rail, the granite base and the support seat with a diamond grinding machine to achieve nanometer level flatness; the porous material plate is combined with a diamond grinding wheel and electrolytic dressing to ensure that the surface is crack-free; the support seat is processed with a laser drilling machine to form gas holes, and the gas holes are rounded to prevent turbulence when the gas is sprayed; Step five, assembly and debugging, making a moving platform, bonding the granite base, the support seat and the porous material plate that have passed the inspection of precision instruments by using an epoxy resin adhesive; adding a guide rail support to the guide rail, assembling sensors and pipeline accessories to the support seat to ensure that the pipeline accessories are sealed with the gas holes; performing air test to observe whether the guide rail moves smoothly; performing load test to ensure that the requirements are met.

[0021] Through the above steps, the high-precision machining of the air floating guide rail can be realized, and the non-contact, low-friction and high-stability movement requirements can be met.

[0022] Advantages 1. Compared with the prior art, the air floating guide rail of one embodiment of the present application utilizes the shape memory alloy material to dynamically control the air supply pressure of the small hole restrictor and the through flow capacity of the micropores of the porous material plate, superimposes the double regulation effects of the dynamic regulation of the small hole restrictor and the air supply dynamic regulation of the porous material plate, not only plays the advantages of uniform air film and stable bearing of the porous ceramic air film, but also overcomes the inherent material property defects of the traditional porous air foot through active regulation of the pressure, realizes dynamic regulation of the pressure and simplification of the system while ensuring uniformity and stability of the air film, compared with the traditional regulation valve scheme, the air path components are reduced, the assembly time is shortened, the equipment installation cost is greatly reduced, and the present application is especially suitable for application of large-size and medium-high-precision air floating platforms, solves the technical problems of large number of valves, maintenance and difficult cooperative control, and large systematic error, and improves the operation precision and efficiency of the equipment.

[0023] 2. The air floating guide rail of another embodiment of the present application is provided with a sealing separation ring between a plurality of throttle holes, utilizes the shape memory alloy material to dynamically control the air supply pressure of the plurality of small hole restrictors, reduces the mutual interference of adjacent throttle holes, realizes independent work of each throttle hole and improvement of the overall performance of the air foot, optimizes the air film pressure regulation precision, and especially for large-size precision platforms, improves the uniformity of the air film pressure and the long-term stability of the system.

[0024] 3. The air floating guide rail manufacturing method provided by the embodiment of the present application can meet the requirements of ultra-high flatness, parallelism, low surface roughness and high-precision machining, meet the movement requirements of non-contact, low friction and high stability of the air floating guide rail, has low processing cost, and can ensure the qualified rate of the air floating guide rail product.

[0025] 4. The porous material plate adopts embedding of the shape memory alloy wire into the porous ceramic material structure, which not only retains the core advantage of uniform air distribution of the porous ceramic through the micropores, but also realizes self-adaptive regulation of the air film pressure through the shape memory effect of the shape memory alloy wire, and realizes dynamic regulation of the pressure and simplification of the system while ensuring uniformity of the air film through the radial layout of the shape memory alloy wire. BRIEF DESCRIPTION OF DRAWINGS

[0026] Figure 1 It is an outline view of the air floating guide rail of the embodiment of the present application; Figure 2 It is a side view of the air floating guide rail of the embodiment of the present application; Figure 3 It is a schematic view of the overall structure of the porous material air floating plate component in the embodiment 1 of the present application; Figure 4 It isFigure 3 Enlarged view at A Figure 5 Structure diagram of small hole throttler component in the embodiment of the present application Figure 6 Structure diagram of special combination joint component in the embodiment of the present application Figure 7 Structure diagram of first special profiled plug component in the embodiment of the present application Figure 8 Structure diagram of porous material plate component in the embodiment 1 of the present application Figure 9 Structure diagram of shape memory alloy wire component in the embodiment 1 of the present application Figure 10 Connection diagram of air floating guide rail and external component in the embodiment 1 of the present application Figure 11 Working surface view of porous material air floating plate component in the embodiment 2 of the present application Figure 12 Figure 12 B-B direction sectional view In the figure: 1, guide rail, 2, moving platform, 3, porous material air floating plate, 4, granite base, 5, support seat, 6, porous material plate, 7, air inlet channel, 8, throttling channel, 9, small hole throttler, 10, groove, 11, throttler pipe seat, 12, center hole, 13, shape memory alloy ring, 14, controller, 15, power supply, 16, first air pressure sensor, 17, limit stop ring, 18, shape memory alloy wire, 19, special combination joint, 20, air compressor, 21, second air pressure sensor, 22, adjusting valve assembly, 23, joint seat, 24, fish scale wire head, 25, branch pipeline, 26, inner hexagonal mounting hole, 27, internal thread through hole, 28, second air pressure sensor seat hole, 29, air pressure test hole, 30, second special profiled plug, 31, general plug, 32, sealing spacer ring, 33, second O-shaped sealing ring, 34, guide rail support, 35, wire, 36, first air pressure sensor seat hole, 37, threading hole, 38, first special profiled plug, 39, first O-shaped sealing ring. DETAILED DESCRIPTION

[0027] ​In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0028] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium; it can be the communication inside 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.

[0029] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, not all the embodiments.

[0030] Embodiment 1, please refer to Figures 1 to 10 A kind of air floatation guide rail, the air floatation guide rail includes guide rail 1 and mobile platform 2 with guide rail 1 by air film sliding fit, mobile platform 2 includes several porous material air floatation plate 3 fixed together;Porous material air floatation plate 3 includes granite pedestal 4, support seat 5 fixed in granite pedestal 4, and porous material plate 6 with the lower end surface of support seat 5 fixed connection, support seat 5 is provided with inlet channel 7 in it, and at least one throttle channel 8 is through with inlet channel 7, throttle channel 8 is installed with small hole throttling device 9 extending to the lower end surface of support seat 5;Groove 10 is opened in the lower end surface of support seat 5, to form air cavity between the lower end surface of support seat 5 and the upper surface of porous material plate 6;Small hole throttling device 9 includes throttling device pipe base 11, the central hole 12 of throttling device pipe base 11 is communicated with throttle channel 8, shape memory alloy ring 13 is arranged in central hole 12, shape memory alloy ring 13 is connected with controller 14 and power supply 15;First air pressure sensor 16 is installed in throttling device pipe base 11, first air pressure sensor 16 is electrically connected with controller 14, and gas pressure parameter in air cavity is transmitted to controller 14;The lower surface of porous material plate 6 as working surface forms air film with guide rail 1.

[0031] Please refer to Figure 1 , Figure 2The cross section of the guide rail 1 is rectangular, and the number of the porous material air floating plates 3 is four. The four porous material air floating plates 3 are fixedly connected and surround the guide rail 1. The four working surfaces of the four porous material air floating plates 3 and the four surfaces of the guide rail 1 form air films, so that the moving platform 2 composed of the four porous material air floating plates 3 is suspended on the guide rail 1. The lower part of the guide rail 1 is further provided with a guide rail support 34.

[0032] In the embodiment, the material of the shape memory alloy ring 13 is NiTi alloy.

[0033] Please refer to Figure 3 , Figure 4 , and Figure 5 , a limiting stop ring 17 is further arranged in the center hole 12 above the shape memory alloy ring 13. The limiting stop ring 17 is used for limiting the movement range of the shape memory alloy ring 13 and reducing the heat loss of the shape memory alloy ring 13. There is a gap between the limiting stop ring 17 and the shape memory alloy ring 13, so as to reduce the deformation resistance of the shape memory alloy ring 13.

[0034] Please refer to Figure 4 , Figure 5 , the center hole 12 of the restrictor pipe base 11 is stepped, the bottom is chamfered, and the middle part is provided with a shape memory alloy ring 13 mounting groove and a limiting stop ring 17 mounting groove from bottom to top. The restrictor pipe base 11 is further provided with a first air pressure sensor seat hole 36 parallel to the center hole 12. The restrictor pipe base 11 is further provided with a threading hole 37 communicating with the center hole 12 and the first air pressure sensor seat hole 36. The outer end of the threading hole 37 is connected with a first special-shaped plug 38 with a through hole through an internal thread. The first air pressure sensor 16 is arranged in the first air pressure sensor seat hole 36. The data line of the first air pressure sensor 16 passes through the through hole of the first special-shaped plug 38. The bottom of the first special-shaped plug 38 and the data line of the first air pressure sensor 16 are further provided with a first O-shaped sealing ring 39.

[0035] The key property of shape memory alloy is "shape memory effect", shape memory alloy can be plastically deformed at low temperature, and will restore to the original shape when heated to the critical phase transition temperature, and the deformation process is accompanied by a large driving force. By using this property, the shape memory alloy ring 13 is placed in the center hole 12 of the restrictor pipe seat 11, the flow area of the flow hole is changed by shape change, and then the gas pressure in the gas cavity is adjusted. When the load of the air floating guide rail increases and the air film pressure is too low, the shape memory alloy ring 13 is expanded by electric heating, the flow area of the flow hole is increased, the flow is increased, and the air film pressure is increased. When the load decreases and the air film pressure is too high, the temperature of the shape memory alloy ring 13 is lowered by power-off, the shape memory alloy ring 13 restores to the original shape, the flow area of the flow hole is reduced, the flow is reduced, and the pressure is stabilized. Compared with the traditional porous gas foot pressure regulating method which depends on external regulating valve, the shape memory alloy ring 13 is embedded to realize "gas foot body self-regulation", and no additional gas path valve is needed for control. Compared with the traditional regulating valve scheme, the number of gas path components is reduced, the assembly time is shortened, and the equipment cost is greatly reduced.

[0036] In the embodiment, the depth of the groove 10 arranged on the lower end surface of the support seat 5 is 1.5 mm.

[0037] The material of the porous material plate 6 is one of sintered graphite, porous aluminum oxide, porous silicon carbide, or porous silicon nitride. In the embodiment, the porous aluminum oxide ceramic is selected.

[0038] Please refer to Figure 8 、 Figure 9 、 Figure 10 , the porous material plate 6 of the embodiment 1 is a combined structure of the shape memory alloy wire 18 embedded in the porous ceramic. The shape memory alloy wire 18 is embedded in the surface layer of the upper surface of the porous material plate 6 to a depth of 0.1-0.2 mm, extends radially from the geometric center to the edge of the porous material plate 6, and the shape memory alloy wire 18 is uniformly distributed along the geometric center of the porous material plate 6. The included angle between the adjacent two shape memory alloy wires 18 is 30°. The connecting wire 35 of the shape memory alloy wire 18 passes through the first air pressure sensor seat hole 36 and the threading hole 37 on the small hole restrictor 9 in turn, and is connected with the controller 14 and the power supply 15.

[0039] Please refer to Figure 9 , the diameter of the shape memory alloy wire 18 decreases uniformly from the center to the edge. The material of the shape memory alloy wire 18 is NiTiCu alloy. The surface of the shape memory alloy wire 18 is plated with an Al2O3 insulating layer with a thickness of 0.01 mm. In the embodiment, the shape memory alloy wire 18 is connected by a low-resistance metal wire 35. The wire 35 generates little heat when electrified, and the shape memory alloy wire 18 generates heat and deforms when electrified.

[0040] When the shape memory alloy wire 18 contracts, a symmetrical radial tension is generated to offset the edge lifting caused by the fluctuation of the air film pressure. The traditional single-point embedded edge deformation can reach ±0.1 mm, and the radial distribution can be controlled within ±0.02 mm. The central area of the porous material plate 6 has more micropores due to the dense shape memory alloy wire 18, and the edge has fewer micropores due to the sparse shape memory alloy wire 18, forming an air film pressure gradient of "high pressure in the center and low pressure at the edge", thereby compensating for the load eccentricity. When the load eccentricity is 10%, the air film thickness deviation can be reduced from ±5% to ±1.5%. The radial distribution of the shape memory alloy wire 18 balances the radial force, and the edge air film thickness deviation is less than ±0.01 mm on a gas foot with a diameter of 300 mm. This distribution is suitable for ultra-precision scenarios such as wafer detection. The diameter of the shape memory alloy wire 18 decreases from the center to the edge, from 0.5 mm at the center to 0.2 mm at the edge, and the angle is 15°-30°. This can ensure that the radial stress gradient is uniform.

[0041] Embedding the shape memory alloy wire 18 in the porous ceramic material retains the core advantage of the porous ceramic of uniform gas distribution through micropores, and realizes adaptive regulation of the air film pressure through the shape memory effect of the shape memory alloy wire 18. This has unique application potential in precision air floating systems. Through the radial layout of the shape memory alloy wire 18, the pressure is dynamically adjusted while ensuring the uniformity of the air film, which is especially suitable for large-size, medium-high-precision air floating platforms.

[0042] The porous ceramic is brittle, and the driving force of the shape memory alloy wire 18 during deformation can reach hundreds of MPa, which can easily cause the ceramic to crack. Low-deformation shape memory alloys such as NiTiCu alloy with a deformation rate of less than 3% are selected to reduce stress on the porous ceramic. The surface layer of the ceramic has a high porosity and is prone to deformation, while the inner layer has a low porosity and high strength. The shape memory alloy wire 18 is embedded in the surface layer of the porous ceramic material, so that the deformation is mainly concentrated in the surface layer, reducing the overall stress and reducing the risk of ceramic cracking. The shape memory alloy wire 18 is sintered with the porous ceramic as a whole, eliminating the need for additional installation space and achieving a compact structure.

[0043] Heating the shape memory alloy wire 18 usually requires heating to 60-100℃, which can cause the ceramic temperature to rise and the gas viscosity to change, affecting the air film pressure. For every 10℃ increase in temperature, the pressure deviation is ±3%. An Al2O3 insulation layer with a thickness of 0.01 mm is plated on the surface of the shape memory alloy wire 18, and only the wire body is heated by electric current, reducing heat transfer to the ceramic. The heat loss is reduced from 30% to 10%. In addition, a pre-calibration algorithm with mature technology can be used to establish a "shape memory alloy temperature-air film pressure" characteristic curve through experiments, and store it in the controller 14 for nonlinear compensation. After compensation, the air film pressure regulation accuracy is improved by 50%.

[0044] Please refer to Figure 6 ,Figure 7 、 Figure 10 , the inlet of the air inlet channel 7 is provided with a special combination joint 19 through screwing, the other end of the special combination joint 19 is communicated with the air compressor 20; the second air pressure sensor 21 is arranged in the special combination joint 19, the second air pressure sensor 21 is electrically connected with the controller 14, the controller 14 is electrically connected with the air compressor 20 and the regulating valve assembly 22 arranged between the special combination joint 19 and the air compressor 20 respectively.

[0045] The special combination joint 19 comprises a joint seat 23 and a fish scale thread 24, the thread end of the fish scale thread 24 is connected with the inner thread hole of the joint seat 23, the end with the fish scale of the fish scale thread 24 is connected with the branch pipeline 25, and the joint seat 23 is connected with the air inlet channel 7 on the support seat 5 through external threads; the joint seat 23 comprises an inner hexagonal mounting hole 26, an internal thread through hole 27 connected with the inner hexagonal mounting hole 26, a second air pressure sensor seat hole 28 parallel to the internal thread through hole 27, and an air pressure test hole 29 communicated with the internal thread through hole 27 and the second air pressure sensor seat hole 28, the outer end of the second air pressure sensor seat hole 28 is connected with the second special thread plug 30 with a through hole through internal threads, the second special thread plug 30 seals the outer end of the second air pressure sensor seat hole 28, the second air pressure sensor 21 is arranged in the second air pressure sensor seat hole 28, the data line of the second air pressure sensor 21 passes through the through hole of the second special thread plug 30, and a second O-shaped sealing ring 33 is further arranged between the bottom of the second special thread plug 30 and the data line of the second air pressure sensor 21, and the outer end of the air pressure test hole 29 is sealed through the general thread plug 31.

[0046] The inlet of the air inlet channel 7 is individually communicated with the external air compressor 20 through the branch pipeline 25, the regulating valve assembly 22 is arranged on the branch pipeline 25, the controller 14 is connected with the air compressor 20 and the regulating valve assembly 22, and the gas pressure entering the air inlet channel 7 is regulated.

[0047] Embodiment 2, please refer to Figure 11 、 Figure 12 , the structure and function of the small hole throttler 9 in embodiment 2 are completely same as those in embodiment 1, a plurality of throttling channels 8 are communicated with the air inlet channel 7 in embodiment 2, the plurality of throttling channels 8 are evenly distributed in a square matrix on the support seat 5, and one small hole throttler 9 is arranged in each throttling channel 8; the sealing spacer ring 32 is further arranged in the groove 10 in embodiment 2, the upper end surface of the sealing spacer ring 32 is tightly attached to and fixed on the lower end surface of the support seat 5, the lower end surface of the sealing spacer ring 32 is tightly attached to the upper surface of the porous material plate 6, and the air cavity is sealed and divided into a plurality of areas by the sealing spacer ring 32, so that the corresponding porous material plate 6 in each area is independently supplied with gas by the small hole throttler 9 in the area.

[0048] Although the sealing spacer ring 32 is not fixedly connected with the porous material plate 6, in order to avoid a large relative displacement under temperature cycle, affecting the control stability of the gas film, the material of the sealing spacer ring 32 should be selected to be close to the thermal expansion coefficient of the material of the porous material plate 6. The sealing spacer ring 32 blocks the lateral flow of gas between adjacent throttle holes, so that the flow regulation of each throttle hole under the driving of the shape memory alloy ring 13 only affects the gas film pressure of the corresponding area, avoiding the coupling problem of “one-hole regulation and multi-area fluctuation”, and the sealing spacer ring 32 can ensure that the flow only acts on the target area and does not “shunt” to the adjacent area.

[0049] The embodiment 1 of the present application also provides a method for manufacturing the air floating guide rail, comprising the following steps: Step one, material selection and blank preparation; the granite base 4 on the guide rail 1 and the porous material air floating plate 3 are all selected to be of granite material, the support block 5 is selected to be of carbon fiber reinforced resin, and the porous material plate 6 is selected to be of alumina ceramic; the granite guide rail 1, the granite base 4 and the support seat 5 blank are cut by using a diamond saw blade, to ensure the basic shape and to be cut to be close to the designed size with a reserved machining allowance of 5-10 mm; the ceramic green body of the porous material plate 6 is prepared, alumina powder with a purity of 99.9% is mixed with a binder to be molded into a green body with embedded holes, the porosity is 25%, the pre-stretched NiTiCu wire with a deformation of 5%-8% is inserted into the green body hole according to the designed path, and the two ends are fixed on the metal base, sintering is carried out at 1600°C for 4 hours, the ceramic is densified, the porosity is less than 5%, and the shape memory alloy wire 18 is mechanically engaged with the ceramic, the interface bonding strength is greater than 50MPa; Step two, rough machining and stress relief; the granite guide rail 1 removes most of the allowance and processes the basic structure of the guide rail surface; the granite base 4, the support seat 5 and the blank surface of the porous material plate 6 are coarsely ground by using a diamond milling cutter or a grinding wheel to remove surface defects such as scratches and pores; the granite guide rail 1, the granite base 4 and the support seat 5 are stress stable, and the stress relief process can be omitted, the stress of the porous material plate 6 after sintering has been basically eliminated, and the porous material plate 6 needs to be annealed at 500-800°C after rough machining to remove the machining stress; Step three, semi-finishing; the granite guide rail 1, the granite base 4, the support seat 5 and the porous material plate 6 are semi-ground by using a diamond grinding wheel, the surface roughness Ra is controlled to be 1.6, the granite base 4 and the support seat 5 are simultaneously processed to have mounting holes, and the groove 10 for storing gas on the support seat 5 has a depth of 0.5-2mm and is milled by using a numerical control milling machine to ensure the contour accuracy of ±0.1mm; The gas hole of the support seat 5 has a diameter of 0.1-0.5mm, and a Φ1-2mm guide hole is pre-drilled to avoid position deviation during subsequent precise punching.

[0050] Step four, finishing; granite guide rail 1, granite base 4, and support seat 5 are finished with a diamond grinding machine, and a nanometer level of flatness is achieved by controlling the grinding pressure at 0.1-0.3 MPa and the rotation speed at 30-50 r / min; the porous material plate 6 is ground with an electrolytic online dressing grinding wheel, and the surface is ensured to be crack-free and the roughness is below Ra 0.05 by combining a diamond grinding wheel and electrolytic dressing; the support seat 5 is processed with a laser drilling machine to form a gas hole with a diameter of Φ0.1-0.5 mm, the position accuracy is ±0.01 mm, the hole wall roughness is below Ra 1.6, the gas hole is rounded with a radius of R0.05 mm to prevent turbulence when the gas is sprayed.

[0051] Step five, assembly and debugging; the moving platform is made by bonding the granite base 4, support seat 5, and porous material plate 6 that have passed the inspection of precision instruments with an epoxy resin adhesive; the guide rail support 34 is added to the guide rail 1, the sensor and pipeline accessories are assembled on the support seat 5 to ensure the sealing of the pipeline accessories and the gas hole; air test: adjust the air source pressure, detect the air film thickness with a dial gauge, the air film thickness is 0.005-0.05 mm, and observe whether the guide rail moves smoothly; load test: apply the designed load, and detect that the air film stiffness deformation is less than 0.001 mm / kg to ensure that the use requirements are met.

[0052] Through the above steps, high-precision processing of the air floating guide rail can be achieved to meet the requirements of non-contact, low friction, and high stability.

[0053] The above examples and drawings are only used to illustrate the technical solutions of the present application and are not a limitation of the present application. The present application is described in detail with reference to the preferred embodiments, and those skilled in the art should understand that changes, modifications, additions or substitutions made by those skilled in the art within the essential scope of the present application do not deviate from the purpose of the present application and should also belong to the protection scope of the claims of the present application. Other related technical structures not described in detail in the present application are the existing technologies in the art.

Claims

1. An air floating guide rail, comprising a guide rail and a moving platform slidingly fitted with the guide rail by an air film, the moving platform comprising a plurality of porous material air floating plates fixed together, characterized in that: The porous material air floating plate comprises a granite base, a supporting seat fixed in the granite base, and a porous material plate fixedly connected with the lower end surface of the supporting seat, an air inlet channel is arranged in the supporting seat, and at least one throttling channel penetrating through the air inlet channel is arranged, a small-hole throttling device is arranged in the throttling channel and extends to the lower end surface of the supporting seat; a groove is arranged on the lower end surface of the supporting seat to form an air cavity between the lower end surface of the supporting seat and the upper surface of the porous material plate; the small-hole throttling device comprises a throttling device tube seat, a center hole of the throttling device tube seat is communicated with the throttling channel, a shape memory alloy ring is arranged in the center hole, the shape memory alloy ring is connected with a controller and a power supply, a first air pressure sensor is arranged in the throttling device tube seat, the first air pressure sensor is electrically connected with the controller, and the air pressure parameter in the air cavity is transmitted to the controller; the lower surface of the porous material plate serves as a working surface and forms an air film with a guide rail.

2. The air floatation guide rail according to claim 1, characterized by: A limiting ring is further arranged in the center hole above the shape memory alloy ring.

3. The air floatation guide rail according to claim 1, wherein: The depth of the groove arranged on the lower end surface of the supporting seat is 0.5-2 mm.

4. The air floatation guide rail according to claim 1, wherein: The material of the porous material plate is one of sintered graphite, porous aluminum oxide, porous silicon carbide, and porous silicon nitride.

5. The air floatation guide rail according to claim 1, wherein: The porous material plate is a combined structure of shape memory alloy wires embedded in porous ceramics; the shape memory alloy wires are embedded in the porous material plate to a depth of 0.1-0.2 mm in the surface layer of the upper surface of the porous material plate, and the shape memory alloy wires are uniformly distributed radially along the geometric center of the porous material plate to the edge, the included angle between two adjacent shape memory alloy wires is 15°-30°, and the connecting wires of the shape memory alloy wires are connected with the controller and the power supply after penetrating through the small-hole throttling device.

6. The air floatation guide rail according to claim 5, wherein: The wire diameter of the shape memory alloy wire uniformly decreases from the center to the edge.

7. The air floatation guide rail according to claim 5, wherein: The material of the shape memory alloy wire is NiTiCu alloy.

8. The air floatation guide rail according to claim 5, wherein: An Al2O3 insulating layer with a thickness of 0.01 mm is plated on the surface of the shape memory alloy wire.

9. The air floatation guide rail according to claim 1, wherein: The air inlet channel is communicated with a plurality of throttling channels, the plurality of throttling channels are uniformly distributed in a circular or square matrix on the supporting seat, one small-hole throttling device is arranged in each throttling channel, a sealing spacer ring is further arranged in the groove, the upper end surface of the sealing spacer ring is tightly attached to and fixed with the lower end surface of the supporting seat, the lower end surface of the sealing spacer ring is tightly attached to the upper surface of the porous material plate, and the sealing spacer ring seals and divides the air cavity into a plurality of areas, so that the corresponding porous material plate in each area is independently supplied with air by the small-hole throttling device in the area.

10. A method of manufacturing an air floating guide rail, characterized by: The preparation of the air floating guide rail of claim 5 comprises the following steps, Step one, material selection and blank preparation, the granite base on the guide rail and the porous material air floating plate are all made of granite, the supporting block is made of carbon fiber reinforced resin, and the porous material plate is made of aluminum oxide; ceramic green body preparation of the porous material plate, mixing of aluminum oxide powder and binder, molding into a green body with embedded holes, penetration of the pre-stretched shape memory alloy wire into the green body hole according to the designed path, fixation of both ends, sintering at high temperature to densify the ceramic, and mechanical interlocking of the shape memory alloy wire and the ceramic; Step two, rough processing and stress relief, granite guide rail removes most of the excess, processing the guide rail surface basic structure; with diamond milling cutter or grinding wheel rough grinding granite pedestal, support seat, and porous material plate blank surface, remove surface defects such as scratches, pores; porous material plate after rough machining need annealing treatment, remove processing stress; Step three, semi-finishing, granite guide rail, granite pedestal, support seat, and porous material plate with diamond grinding wheel semi-finishing, so as to achieve the surface roughness standard, granite pedestal and support seat are machined at the same time installation hole; support seat groove for storing gas, using CNC milling machine milling, to ensure the contour accuracy; support seat gas hole pre-drill guide hole, to avoid subsequent precise punching position deviation; Step four, finishing, granite guide rail, granite pedestal, and support seat, with diamond grinding machine for fine grinding, to achieve nanometer level flatness; porous material plate combined with diamond grinding wheel and electrolytic dressing, to ensure the surface without cracks; support seat with laser drilling machine processing gas hole, to prevent the gas injection when the turbulence; Step five, assembly and debugging, making the moving platform, the granite pedestal, support seat, and porous material plate which are tested by precision instruments, are bonded by epoxy resin adhesive; installing guide rail support for guide rail, assembling sensor and pipeline accessories on the support seat, to ensure the pipeline accessories and gas hole sealing; air test, to observe whether the guide rail movement is smooth; load test, to ensure that it meets the use requirements.

Images