Air floating guide rail and manufacturing method

Abstract

The application belongs to the technical field of precision equipment, and discloses a kind of air floatation guide rail and manufacturing method, the air floatation guide rail includes guide rail and the moving platform that is slid with air film with the guide rail, the moving platform includes several porous material air floatation plates fixed together;The porous material air floatation plate includes granite pedestal, support seat fixed in granite pedestal, and the lower end surface of the support seat is fixedly connected with porous material plate;The application utilizes shape memory alloy material dynamic control small hole throttler's gas supply pressure and the micro-pore flow capacity of porous material plate, superimposes the double regulation effect of small hole throttler dynamic adjustment and porous material plate ventilation dynamic adjustment, overcomes the inherent material characteristic defects of traditional porous air foot, compared with traditional regulating valve scheme, equipment cost is greatly reduced, especially suitable for large size, medium-high precision air floatation platform application, improves the operation precision and efficiency of equipment.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of precision equipment, and relates to an air floating guide rail and a manufacturing method. BACKGROUND

[0002] The air floating guide rail is widely applied to 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 air floating guide rail include a guide rail and a moving platform, and the moving platform is also called a slider or a slide plate. The moving platform is separated from the guide rail by an air film to realize smooth movement without friction. The air foot is a key component in the air floating system of the moving platform. The air foot introduces compressed air into the air cavity through the air inlet, and adjusts the compressed air to be uniformly sprayed from the small holes at the bottom or side of the air foot through the throttle, so as to form a thin air film between the moving platform and the guide rail. The air foot is divided into a porous air foot, a small hole throttle air foot and a groove type air foot. The porous air foot realizes uniform distribution of gas by virtue of the micro-porous structure, and is applied in precision air floating support, such as a workpiece table of a photoetching machine and an ultra-precision guide rail.

[0003] The porous air foot has the following deficiencies due to the limitation of material characteristics: the air outlet uniformity of the porous air foot completely depends on the distribution density and aperture consistency of the internal micro-pores. It is difficult to realize an absolutely uniform micro-porous structure by using the existing manufacturing process. The local micro-porous dense area is prone to "excessive air outlet", which causes the local pressure of the air 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 air outlet, which causes the thickness of the air film to be uneven and affects the flatness precision of the load. This non-uniformity is more prominent in large-size air feet, which limits the application of the air feet in the ultra-large area support scene. Therefore, a large-size moving platform needs to increase the number of air feet to avoid the air film being uneven due to too large span, and the increase in the number of air feet leads to complex air path and cost soaring. Each increase in the number of air feet needs independent or grouped air supply, which leads to a fold increase in the number of air path pipelines, sensors and valve components. For example, a workpiece table of a photoetching machine adopts 20 air feet, and needs to be matched with 20 high-precision pressure regulating valves, which causes difficulties in equipment maintenance and collaborative control of multiple air feet, and also causes system errors.

[0004] How to match materials, optimize structures and control compensation to realize the application value of the porous material in the medium and high precision air floating system, especially in the application of large-size platforms, has become a technical problem to be solved by the technical personnel in the field, that is, to control the cost and improve the precision by reasonable structural design. SUMMARY

[0005] To solve the technical problems of the prior art that the porous air foot is limited by material properties, local air film pressure is too high, or air film thickness is uneven, causing the support platform to micro-vibrate, affecting the flatness accuracy of the load, and the porous air foot has high cost, difficult maintenance and coordination control, and large systematic error in large-size moving platform applications, the application provides a gas floating guide rail and a manufacturing method.

[0006] The application solves the above technical problems by the following technical scheme, and provides a gas floating guide rail, which comprises a guide rail and a moving platform in sliding cooperation with the guide rail through an air film, the moving platform comprises a plurality of porous material floating plates fixed together, the porous material floating plate comprises a granite base, a support seat fixed in the granite base, and a porous material plate fixedly connected with the lower end surface of the support seat, an air inlet channel is arranged in the support seat, and at least one throttling channel penetrating through the air inlet channel is arranged, a small-hole throttler extending to the lower end surface of the support seat is arranged in the throttling channel, a groove is formed in the lower end surface of the support seat to form an air cavity between the lower end surface of the support seat and the upper surface of the porous material plate, the small-hole throttler comprises a throttler pipe seat, the center hole of the throttler pipe seat is in communication 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 throttler pipe seat, the first air pressure sensor is electrically connected with the controller, and the gas pressure parameter in the air cavity is transmitted to the controller, and the lower surface of the porous material plate serves as a working surface and forms an air film with the guide rail.

[0007] Further, the cross section of the guide rail is rectangular, the number of the porous material floating plates is four, the four porous material floating plates are fixedly connected and surround the periphery of the guide rail, and the four working surfaces of the four porous material floating plates form air films with the four surfaces of the guide rail, so that the moving platform composed of the four porous material floating plates is suspended on the guide rail.

[0008] Further, the lower part of the guide rail is further provided with a guide rail support.

[0009] Further, the material of the shape memory alloy ring is NiTi alloy.

[0010] Further, a limiting ring is further arranged in the center hole above the shape memory alloy ring.

[0011] Further, the center hole of the restrictor seat is stepped, the bottom is chamfered, and the middle part is provided with a shape memory alloy ring mounting groove and a limiting ring mounting groove from bottom to top, respectively; the restrictor seat is further provided with a first air pressure sensor seat hole parallel to the center hole; the restrictor seat is provided with a threading hole communicating 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 the bottom of the first special-shaped plug and the data line of the first air pressure sensor are further provided with a first O-shaped sealing ring.

[0012] Further, the depth of the groove provided on the lower end surface of the support seat is 0.5-2 mm.

[0013] Further, the material of the porous material plate is one of sintered graphite, porous aluminum oxide, porous silicon carbide, or porous silicon nitride.

[0014] 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 depth of 0.1-0.2 mm of 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, and the included angle between two adjacent shape memory alloy wires is 15°-30°; the connecting wires of the shape memory alloy wires are connected with the controller and the power supply after passing through the small hole restrictor.

[0015] Further, the diameter of the shape memory alloy wire decreases uniformly from the center to the edge.

[0016] Further, the material of the shape memory alloy wire is NiTiCu alloy.

[0017] Further, the surface of the shape memory alloy wire is plated with an Al2O3 insulating layer with a thickness of 0.01 mm.

[0018] Further, the inlet of each air inlet channel is provided with a special combination joint installed through threads, and the other end of the special combination joint is communicated with an air compressor; a second air pressure sensor is installed in the special combination joint, and the second air pressure sensor is electrically connected with a controller; and the controller is electrically connected with the air compressor and a regulating valve assembly provided between the special combination joint and the air compressor.

[0019] Further, the special combination joint comprises a joint seat and a fish scale thread, the thread end of the fish scale thread is connected with the inner thread hole of the joint seat, the end with fish scale of the fish scale thread is connected with the branch pipeline, and the joint seat is connected with the air inlet channel on the support seat through external threads; the joint seat comprises an inner hexagonal mounting hole, an internal thread through hole connected with the inner hexagonal mounting hole, a second air pressure sensor seat hole parallel to the internal thread through hole, and an air pressure test hole connected with the internal thread through hole and the second air pressure sensor seat hole; the outer port of the second air pressure sensor seat hole is connected with a second special thread plug with a through hole through internal threads, the second special thread plug seals the outer port of the second air pressure sensor seat hole, the second air pressure sensor is arranged inside the second air pressure sensor seat hole, the data line of the second air pressure sensor passes through the through hole on the second special thread plug, and a second O-shaped sealing ring is further arranged between the bottom of the second special thread 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 thread plug.

[0020] 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 separation ring is further arranged in the groove, the upper end face of the sealing separation ring is tightly attached to and fixed with the lower end face of the support seat, the lower end face of the sealing separation ring is tightly attached to the upper surface of the porous material plate, and the sealing separation 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.

[0021] The application further provides a gas floating guide rail manufacturing method, which comprises the following steps:

[0022] Step one, material selection and blank preparation, the granite base on the guide rail and the porous material plate is selected to be granite, the support block is selected to be carbon fiber reinforced resin, and the porous material plate is selected to be alumina; ceramic green body preparation of the porous material plate, alumina powder is mixed with a binder, and a green body with embedded holes is formed by molding, the pre-stretched shape memory alloy wire is inserted into the green body hole according to the designed path, the two ends are fixed, and sintering is carried out at high temperature to densify the ceramic and form mechanical engagement between the shape memory alloy wire and the ceramic;

[0023] Step two, rough machining and stress relief, most of the excess of the granite guide rail is removed, and the basic structure of the guide rail surface is machined; the granite base, the support seat and the blank surface of the porous material plate are coarsely ground by using a diamond milling cutter or a grinding wheel to remove surface defects such as scratches and pores; the porous material plate needs to be annealed after rough machining to remove machining stress;

[0024] Step three, semi-finishing, granite guide rail, granite base, support seat, and porous material plate are semi-ground by diamond grinding wheel to reach the surface roughness standard, and the granite base and support seat are machined with 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 of the support seat is pre-drilled with a guide hole to avoid position deviation during subsequent precise punching;

[0025] Step four, finishing, the granite guide rail, granite base, and support seat are precisely ground by 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 a crack-free surface; the gas hole of the support seat is machined by a laser punching machine and rounded to prevent turbulence during gas injection;

[0026] Step five, assembly and debugging, the granite base, support seat, and porous material plate that have passed the inspection of precision instruments are bonded by an epoxy resin adhesive; a guide rail support is added to the guide rail, sensors and pipeline accessories are assembled onto the support seat to ensure the sealing of the pipeline accessories and the gas hole; air test is performed to observe whether the guide rail moves smoothly; load test is performed to ensure that the requirements are met.

[0027] Through the above steps, high-precision machining of the air floating guide rail can be achieved to meet the requirements of non-contact, low friction, and high stability.

[0028] Advantages

[0029] 1. Compared with the prior art, the air floating guide rail of one embodiment of the present application uses shape memory alloy material to dynamically control the gas supply pressure of the small hole restrictor and the through-flow capacity of the micro-holes of the porous material plate, superimposes the double regulation effects of dynamic adjustment of the small hole restrictor and dynamic adjustment of the porous material plate, not only takes advantage of the uniformity and stability of the porous ceramic air film, but also overcomes the inherent material property defects of traditional porous gas feet through active pressure adjustment, ensures the uniformity and stability of the air film, realizes dynamic adjustment of the pressure and simplification of the system, reduces the number of air path components compared with the traditional regulation valve scheme, shortens the assembly time, greatly reduces the equipment installation cost, is especially suitable for large-size and medium-high-precision air floating platforms, solves the technical problems of too many valves, difficult maintenance and cooperative control, and large systematic errors, and improves the operation precision and efficiency of the equipment.

[0030] 2. The air floating guide rail of another embodiment of the present application is provided with a sealing ring between a plurality of throttle holes, uses a memory material to dynamically control the gas supply pressure of a plurality of small hole restrictors, reduces the mutual interference between adjacent throttle holes, realizes independent work of each throttle hole and improvement of the overall performance of the gas 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.

[0031] 3. The air floating guide rail manufacturing method provided by the embodiment of the present application can meet the requirements of high-precision machining of super-high flatness, parallelism and low surface roughness, meet the motion requirements of air floating guide rail of non-contact, low friction and high stability, has low machining cost and can ensure the qualified rate of air floating guide rail products.

[0032] 4. The porous material plate adopts embedding shape memory alloy wires into the porous ceramic material structure, which not only retains the core advantage of uniform air distribution through micropores of the porous ceramic, but also realizes adaptive regulation and control of the air film pressure through the shape memory effect of the shape memory alloy wires, and realizes dynamic regulation of the pressure and simplification of the system while ensuring the uniformity of the air film through the radial layout of the shape memory alloy wires. BRIEF DESCRIPTION OF DRAWINGS

[0033] Figure 1 It is an outer shape schematic diagram of the air floating guide rail of the embodiment of the present application;

[0034] Figure 2 It is a side view of the air floating guide rail of the embodiment of the present application;

[0035] Figure 3 It is a whole structure schematic diagram of the porous material air floating plate component in the embodiment 1 of the present application;

[0036] Figure 4 It is Figure 3 It is an enlarged view of A in the embodiment of the present application;

[0037] Figure 5 It is a structure component schematic diagram of the small hole throttler component in the embodiment of the present application;

[0038] Figure 6 It is a special combined joint component schematic diagram of the embodiment of the present application;

[0039] Figure 7 It is a first special-shaped plug component structure schematic diagram of the embodiment of the present application;

[0040] Figure 8 It is a local structure diagram of the porous material plate component in the embodiment 1 of the present application;

[0041] Figure 9 It is a shape memory alloy wire component structure schematic diagram of the embodiment 1 of the present application;

[0042] Figure 10 It is a connection schematic diagram of the air floating guide rail and external components in the embodiment 1 of the present application;

[0043] Figure 11 It is a working surface view of the porous material air floating plate component in the embodiment 2 of the present application;

[0044] Figure 12 It is Figure 12Fig. 2 is a cross-sectional view of the B-B direction in Fig. 1;

[0045] Fig. 1 is a schematic diagram of the air floating device of the application, wherein 1 is a guide rail, 2 is a moving platform, 3 is a porous material air floating plate, 4 is a granite base, 5 is a supporting seat, 6 is a porous material plate, 7 is an air inlet channel, 8 is a throttling channel, 9 is a small hole throttler, 10 is a groove, 11 is a throttler pipe seat, 12 is a center hole, 13 is a shape memory alloy ring, 14 is a controller, 15 is a power supply, 16 is a first air pressure sensor, 17 is a limiting stop ring, 18 is a shape memory alloy wire, 19 is a special combined joint, 20 is an air compressor, 21 is a second air pressure sensor, 22 is an adjusting valve assembly, 23 is a joint seat, 24 is a fish scale wire head, 25 is a branch pipeline, 26 is an inner hexagonal mounting hole, 27 is an internal thread through hole, 28 is a second air pressure sensor seat hole, 29 is an air pressure test hole, 30 is a second special profiled plug, 31 is a general plug, 32 is a sealing spacer ring, 33 is a second O-shaped sealing ring, 34 is a guide rail support, 35 is a wire, 36 is a first air pressure sensor seat hole, 37 is a threading hole, 38 is a first special profiled plug, and 39 is a first O-shaped sealing ring. DETAILED DESCRIPTION

[0046] In the description of the 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 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 application. In addition, the terms "first", "second", "third" are only for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0047] In the description of the application, it should be noted that unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection, or integrally connected; it can be mechanical connection, or electrical connection; it can be directly connected, or indirectly connected through an intermediate medium, or the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the application can be understood according to the specific circumstances.

[0048] The technical solutions in the embodiments of the application will be described clearly and completely below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all.

[0049] Embodiment 1, please refer to Figures 1 to 10The air floating guide rail comprises a guide rail 1 and a moving platform 2 which is slidably connected with the guide rail 1 through an air film, the moving platform 2 comprises a plurality of porous material air floating plates 3 which are fixed together; the porous material air floating plate 3 comprises a granite base 4, a supporting seat 5 which is fixed in the granite base 4, and a porous material plate 6 which is fixedly connected with the lower end surface of the supporting seat 5, the supporting seat 5 is provided with an air inlet channel 7 and at least one throttling channel 8 which is in communication with the air inlet channel 7, and a small hole throttling device 9 which extends to the lower end surface of the supporting seat 5 is arranged in the throttling channel 8; a groove 10 is formed in the lower end surface of the supporting seat 5 so as to form an air cavity between the lower end surface of the supporting seat 5 and the upper surface of the porous material plate 6; the small hole throttling device 9 comprises a throttling device tube seat 11, a central hole 12 of the throttling device tube seat 11 is in communication with the throttling channel 8, a shape memory alloy ring 13 is arranged in the central hole 12, the shape memory alloy ring 13 is connected with a controller 14 and a power supply 15; a first air pressure sensor 16 is arranged in the throttling device tube seat 11, the first air pressure sensor 16 is electrically connected with the controller 14 and transmits the gas pressure parameter in the air cavity to the controller 14; the lower surface of the porous material plate 6 serves as a working surface and forms an air film with the guide rail 1.

[0050] Please refer to Figure 1 、 Figure 2 The 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, and the four working surfaces of the four porous material air floating plates 3 form air films with the four surfaces of the guide rail 1, so that the moving platform 2 which is composed of the four porous material air floating plates 3 is suspended on the guide rail 1, and the lower part of the guide rail 1 is further provided with a guide rail support 34.

[0051] The material of the shape memory alloy ring 13 is NiTi alloy.

[0052] Please refer to Figure 3 、 Figure 4 , and Figure 5 A limiting stop ring 17 is further arranged in the central hole 12 above the shape memory alloy ring 13, the limiting stop ring 17 is used for limiting the moving range of the shape memory alloy ring 13 and reducing the heat loss of the shape memory alloy ring 13, and 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.

[0053] Please refer to Figure 4 、 Figure 5The center hole 12 of the throttle seat 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 ring 17 mounting groove from bottom to top. The throttle seat 11 is further provided with a first air pressure sensor seat hole 36 parallel to the center hole 12. The throttle seat 11 is 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 internal threads. The first air pressure sensor 16 is mounted 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 is further provided with a first O-shaped sealing ring 39 between the data line of the first air pressure sensor 16.

[0054] The key feature of the shape memory alloy is the "shape memory effect". The shape memory alloy can be plastically deformed at low temperature. When heated to the critical phase transition temperature, it will return to the original shape. The deformation process is accompanied by a large driving force. By using this feature, the shape memory alloy ring 13 is placed in the center hole 12 of the throttle seat 11. The flow area of the throttle hole is changed by shape change, and then the gas pressure in the air chamber 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 area of the throttle 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 deformation is restored, the area of the throttle hole is reduced, the flow is reduced, and the pressure is stabilized. The pressure regulation of the traditional porous air foot depends on the external regulating valve, and the shape memory alloy ring 13 can realize "air foot body self-regulation" after embedding, without additional air path valve control. Compared with the traditional regulating valve scheme, the air path components are reduced, the assembly time is shortened, and the equipment cost is greatly reduced.

[0055] In the embodiment, the depth of the groove 10 arranged on the lower end surface of the support seat 5 is 1.5 mm.

[0056] 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.

[0057] Please refer to Figure 8 、 Figure 9 、 Figure 10The porous material plate 6 of the embodiment 1 is a combined structure of shape memory alloy wires 18 embedded in porous ceramic, the shape memory alloy wires 18 are embedded in the 0.1-0.2mm deep layer of the upper surface of the porous material plate 6, and extend radially from the geometric center to the edge of the porous material plate 6, and the shape memory alloy wires 18 are evenly distributed along the geometric center of the porous material plate 6, and the included angle between two adjacent shape memory alloy wires 18 is 30°; the connecting wires 35 of the shape memory alloy wires 18 pass through the first air pressure sensor seat hole 36 and the threading hole 37 on the small hole restrictor 9 in turn, and are connected with the controller 14 and the power supply 15.

[0058] 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 0.01mm. In this embodiment, the shape memory alloy wires 18 are connected by low-resistance metal wires 35, and the wires 35 generate little heat when electrified, and the shape memory alloy wires 18 generate heat and deform when electrified.

[0059] When the shape memory alloy wire 18 contracts, it generates symmetrical radial tension, which offsets the edge lifting caused by the fluctuation of the air film pressure. The traditional single-point embedded edge deformation can reach ±0.1mm, and the radial distribution can be controlled within ±0.02mm. The center area of the porous material plate 6 has more micro-holes due to the dense shape memory alloy wires 18, and the edge has fewer micro-holes due to the sparse shape memory alloy wires 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 force balance of the radial distribution of the shape memory alloy wire 18 realizes the edge air film thickness deviation less than ±0.01mm on the air foot with a diameter of 300mm. This distribution method is suitable for ultra-precision scenes such as wafer detection. The diameter of the shape memory alloy wire 18 decreases from the center to the edge, from 0.5mm at the center to 0.2mm at the edge, and the included angle is 15°-30°, which can ensure the uniformity of the radial stress gradient.

[0060] Embedding the shape memory alloy wire 18 into the porous ceramic material not only retains the core advantage of the porous ceramic in uniformly distributing air through the micro-holes, but also realizes the self-adaptive regulation of the air film pressure through the shape memory effect of the shape memory alloy wire 18, which has unique application potential in precision air floating systems. Through the radial distribution of the shape memory alloy wire 18, the uniformity of the air film is ensured, and the dynamic regulation of the pressure and the simplification of the system are realized, which is especially suitable for large-size and medium-high-precision air floating platforms.

[0061] The porous ceramic is brittle, and the driving force of the shape memory alloy wire 18 when deformed can reach several hundred MPa, which is easy to cause the ceramic to crack. A low deformation shape memory alloy, such as a NiTiCu alloy with a deformation rate of less than 3%, is selected to reduce the stress on the porous ceramic; the porosity of the ceramic surface layer 0.1-0.2mm is high and easy to deform, and the porosity of the inner layer is low and the strength is high. 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 ceramic cracking. The shape memory alloy wire 18 is sintered with the porous ceramic as a whole, without the need for additional installation space, and the structure is compact.

[0062] The shape memory alloy wire 18 usually needs to be heated to 60-100℃, which causes the temperature of the ceramic to rise, the gas viscosity to change, and the gas film pressure to be affected. For every 10℃ rise in temperature, the pressure deviation is ±3%. An Al2O3 insulation layer 0.01mm thick is plated on the surface of the shape memory alloy wire 18, only the wire body is heated by current, reducing heat transfer to the ceramic, and 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-gas film pressure" characteristic curve through experiments and store it in the controller 14 for nonlinear compensation. After compensation, the gas film pressure regulation accuracy is improved by 50%.

[0063] 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 screw installation, and the other end of the special combination joint 19 is communicated with the air compressor 20; the second air pressure sensor 21 is installed in the special combination joint 19, and 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 adjusting valve assembly 22 arranged between the special combination joint 19 and the air compressor 20.

[0064] The special combination joint 19 includes 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 includes 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 connecting the internal thread through hole 27 and the second air pressure sensor seat hole 28, the outer port of the second air pressure sensor seat hole 28 is connected with a second special thread plug 30 with a through hole through internal threads, the second special thread plug 30 seals the outer port of the second air pressure sensor seat hole 28, the second air pressure sensor 21 is arranged inside the second air pressure sensor seat hole 28, the data line of the second air pressure sensor 21 passes through the through hole on 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 port of the air pressure test hole 29 is sealed through a general thread plug 31.

[0065] The inlet of the air inlet channel 7 is individually communicated with the external air compressor 20 through the branch pipeline 25, the branch pipeline 25 is provided with an adjusting valve assembly 22, the controller 14 is connected with the air compressor 20 and the adjusting valve assembly 22, and the gas pressure entering the air inlet channel 7 is adjusted.

[0066] In example 2, please refer to Figure 11 , Figure 12 The structure and function of the small hole throttler 9 in example 2 are completely same as those in example 1, a plurality of throttling channels 8 are communicated with the air inlet channel 7 in example 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; a sealing partition ring 32 is further arranged in the groove 10 in example 2, the upper end face of the sealing partition ring 32 is tightly attached to and fixed on the lower end face of the support seat 5, the lower end face of the sealing partition ring 32 is tightly attached to the upper surface of the porous material plate 6, and the sealing partition ring 32 divides the air cavity into a plurality of areas, so that the corresponding porous material plate 6 in each area is independently supplied with air by the small hole throttler 9 in the area.

[0067] Although the sealing partition ring 32 is not fixedly connected with the porous material plate 6, in order to avoid a relatively large displacement under temperature cycle and affect the control stability of the air film, the material of the sealing partition ring 32 should be selected to have a thermal expansion coefficient close to that of the porous material plate 6. The sealing partition ring 32 blocks the transverse flow of gas between adjacent throttling holes, so that the flow regulation of each throttling hole under the driving of the shape memory alloy ring 13 only affects the air film pressure of the corresponding area, avoiding the coupling problem of "one-hole regulation and multi-area fluctuation", and the sealing partition ring 32 can ensure that the flow only acts on the target area and does not "shunt" to the adjacent area.

[0068] The embodiment 1 of the present application also provides a method for manufacturing the air floating guide rail, comprising the following steps:

[0069] Step one, material selection and blank preparation; the guide rail 1 and the granite base 4 on the porous material air floating plate 3 are both selected to be granite material, the supporting block 5 is selected to be carbon fiber reinforced resin, and the porous material plate 6 is selected to be alumina ceramic; the granite guide rail 1, the granite base 4 and the supporting seat 5 blank are cut by using a diamond saw blade, the basic shape is ensured, and the cutting is performed to be close to the designed size with a reserved 5-10mm machining allowance; the ceramic green body of the porous material plate 6 is prepared, the alumina powder with a purity of 99.9% is mixed with a binder, and the green body with embedded holes is formed by die pressing, 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 both ends are fixed on the metal base, sintering is performed at 1600℃ 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, and the interface bonding strength is greater than 50MPa;

[0070] 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 diamond milling cutter or the grinding wheel is used to coarsely grind the blank surface of the granite base 4, the supporting seat 5 and the porous material plate 6, and surface defects such as scratches and pores are removed; the granite guide rail 1, the granite base 4 and the supporting 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 annealing treatment at 500-800℃ is required after rough machining to remove the machining stress;

[0071] Step three, semi-finishing; the granite guide rail 1, the granite base 4, the supporting seat 5 and the porous material plate 6 are semi-finished by using the diamond grinding wheel, and the surface roughness Ra1.6 is controlled, the granite base 4 and the supporting seat 5 are simultaneously machined to form mounting holes, the groove 10 for storing gas on the supporting seat 5 has a depth of 0.5-2mm, and the contour accuracy is ±0.1mm by using the numerical control milling machine;

[0072] The gas hole of the supporting 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] 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, the air-floating guide rail comprising a guide rail and a movable platform that slides with the guide rail via an air film, the movable platform comprising a plurality of porous material air-floating plates fixed together, characterized in that: The porous material air flotation plate includes a granite base, a support fixed within the granite base, and a porous material plate fixedly connected to the lower end face of the support. The support has an air inlet channel and at least one throttling channel communicating with the air inlet channel. A small-hole throttling device extending to the lower end face of the support is installed inside the throttling channel. A groove is formed on the lower end face of the support to create an air cavity between the lower end face of the support and the upper surface of the porous material plate. The small-hole throttling device includes a throttling device seat, the central hole of which communicates with the throttling channel. A shape memory alloy ring is disposed in the central hole, and the shape memory alloy ring is connected to a controller and a power supply. A first air pressure sensor is installed inside the throttling device seat, and the first air pressure sensor is electrically connected to the controller to transmit the gas pressure parameters in the air cavity to the controller. The lower surface of the porous material plate serves as a working surface, forming an air film between it and the guide rail. The porous material plate is a composite structure in which shape memory alloy wires are embedded in porous ceramics. The shape memory alloy wires are embedded 0.1-0.2 mm below the surface layer of the upper surface of the porous material plate, and the shape memory alloy wires are evenly distributed radially from the geometric center of the porous material plate to the edge. The included angle between two adjacent shape memory alloy wires is 15°-30°. The connecting wires of the shape memory alloy wires are connected to the controller and the power supply after passing through the small hole throttling device. The wire diameter of the shape memory alloy wires decreases evenly from the center to the edge.

2. The air-bearing guide rail according to claim 1, characterized in that: A limit stop ring is also provided in the center hole above the shape memory alloy ring.

3. The air-bearing guide rail according to claim 1, characterized in that: The depth of the groove on the lower end face of the support is 0.5-2mm.

4. The air-bearing guide rail according to claim 1, characterized in that: The porous material plate is made of one of the following: sintered graphite, porous alumina, porous silicon carbide, or porous silicon nitride.

5. The air-bearing guide rail according to claim 1, characterized in that: The shape memory alloy wire is made of NiTiCu alloy.

6. The air-bearing guide rail according to claim 1, characterized in that: The surface of the shape memory alloy wire is coated with a 0.01 mm thick Al2O3 insulating layer.

7. The air-bearing guide rail according to claim 1, characterized in that: The intake channel connects to multiple throttling channels, which are evenly distributed on the support base in a circular or square matrix. Each throttling channel is equipped with a small-hole throttler. A sealing ring is also provided in the groove. The upper end face of the sealing ring is tightly attached and fixed to the lower end face of the support base, and the lower end face of the sealing ring is tightly attached to the upper surface of the porous material plate. The sealing ring seals and divides the air chamber into multiple regions, so that the corresponding porous material plate in each region is supplied with air by the small-hole throttler in that region.

8. A method for manufacturing an air-bearing guide rail, characterized in that: The preparation of the air-bearing guide rail according to claim 1 includes the following steps: Step 1: Material selection and blank preparation. Granite is selected for the guide rail and the granite base on the porous material air-float plate. Carbon fiber reinforced resin is selected for the support block, and alumina is selected for the porous material plate. For the preparation of the ceramic green body of the porous material plate, alumina powder is mixed with binder and molded into a green body with embedded holes. Pre-stretched shape memory alloy wire is inserted into the green body hole according to the design path, and the two ends are fixed. It is sintered at high temperature to densify the ceramic. At the same time, the shape memory alloy wire and the ceramic form a mechanical interlock. Step 2: Rough machining and stress relief. Remove most of the excess material from the granite guide rail to machine the basic structure of the guide rail surface. Use a diamond milling cutter or grinding wheel to rough grind the granite base, support base, and the rough surface of the porous material plate to remove scratches and surface defects such as pores. After rough machining, the porous material plate needs to be annealed to remove machining stress. Step 3: Semi-finishing. The granite guide rail, granite base, support base, and porous material plate are semi-finished with diamond grinding wheels to achieve the surface roughness standard. Mounting holes are machined on the granite base and support base at the same time. The groove for storing gas on the support base is milled with a CNC milling machine to ensure the contour accuracy. The air holes of the support base are pre-drilled with guide holes to avoid positional deviations during subsequent precision drilling. Step 4: Fine machining. The granite guide rail, granite base, and support base are finely ground with a diamond grinding machine to achieve nanoscale flatness. The porous material plate is combined with diamond grinding wheel and electrolytic dressing to ensure that the surface is free of cracks. The support base is machined with a laser drilling machine to process air holes, and the air holes are rounded to prevent turbulence during gas injection. Step 5: Assembly and Debugging. The mobile platform is fabricated by bonding the granite base, support, and porous material plate (all inspected and certified using precision instruments) with epoxy resin adhesive. Guide rail supports are installed on the guide rails, and sensors and piping accessories are assembled onto the supports, ensuring a seal between the piping accessories and the vents. An air permeability test is conducted to observe the smoothness of the guide rail movement. A load test is performed to ensure that the requirements are met.

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