Ultra-precise active intelligent porous static pressure gas bearing and implementation method thereof

Abstract

The invention provides an ultra-precise active intelligent porous static pressure gas bearing and an implementation method thereof, and provides an innovative solution based on a semiconductor-based MEMS (Micro Electro Mechanical System) bearing surface to solve the problem of instability of a gas hammer effect caused by uncontrollable surface structure and non-uniform pores of a traditional porous bearing. According to the bearing, a semiconductor material (such as SiC or Si) is uniformly deposited on the surface of a porous substrate, and processes of mechanical grinding, chemical mechanical polishing, photoetching slotting and the like are combined, so that the submicron-level precision and the nano-level roughness of the surface of the bearing are realized, the rigidity is remarkably improved, and the vibration of an air hammer is avoided. Besides, through the piezoresistive effect of a semiconductor material, MEMS elements such as a comb capacitive acceleration sensor and a thermistor are integrated, so that the bearing has the self-monitoring capability, and the service states such as pressure, temperature and vibration can be sensed in real time. The working stability and the intelligent level of the bearing are remarkably improved, and the bearing is suitable for a precision mechanical system in a high-load, high-speed and complex environment.

Description

Technical Field

[0001] The present invention relates to the technical field of porous air bearings, and particularly provides an ultra-precision active and intelligent porous hydrostatic gas bearing and a method for realizing the same. Background Art

[0002] With the increasing demand for high-performance bearings in industry, especially in high-load, high-speed, and complex environments, traditional porous bearings have uncontrollable surface structures and uneven surface pores, which can cause dead zones on the surface and trigger the hammer effect, resulting in bearing instability. Therefore, an ultra-precision active and intelligent porous hydrostatic gas bearing and a method for realizing the same are proposed. Summary of the Invention

[0003] To solve the problems of uncontrollable surface structure and uneven surface pores existing in traditional porous bearings, the present invention proposes an ultra-precision active and intelligent porous hydrostatic gas bearing and a manufacturing method thereof. By integrating multiple technologies to solve the limitations of traditional processes, precise surface air permeability and controllable air permeability are achieved, and at the same time, the bearing has the ability of sensing during use. The technical solution of the present invention is as follows:

[0004] To solve the problems existing in the prior art, the core principle and processing steps of the present invention are as follows:

[0005] (1) Aiming at the problems of low surface accuracy, a large number of irregular pores introducing air capacitance, and single bearing performance in traditional porous bearings, by deeply integrating a semiconductor-based MEMS bearing surface into the porous bearing, the porous hydrostatic gas bearing can finally have sub-micron surface accuracy to improve stiffness, a large number of regular micro-pores to suppress the hammer effect, the ability to actively sense the bearing performance, and the ability to intelligently regulate the bearing performance;

[0006] (2) The semiconductor material on the bearing surface can be SiC or Si, and is uniformly deposited on the surface of the porous bearing by methods such as chemical vapor deposition (CVD), chemical vapor reaction (CVR), and liquid infiltration reaction, thereby ensuring the bonding strength between the bearing surface and the semiconductor material.

[0007] (3) By processing the semiconductor material on the bearing surface through mechanical grinding or chemical mechanical polishing (CMP) process, the surface shape accuracy of the bearing can reach sub-micron level and the roughness can reach nano level, solving the problem of poor surface accuracy of traditional porous hydrostatic gas bearings, which is beneficial for the bearing to reduce the gas film thickness to sub-micron level to improve the stiffness of the bearing; (4) Based on LIGA, laser ablation or soft lithography technology, the thinned and polished bearing surface is grooved by using light energy to obtain a preset MEMS regular flow channel or pore system on the bearing surface, realizing precise reconstruction of the bearing permeability, ensuring the air permeability of the bearing, and avoiding the hammer vibration of the bearing due to the regular flow channel or pore.

[0008] (5)Combined with the special piezoresistive effect of semiconductor materials, it can sense the pressure change of the bearing surface. At the same time, the special thermomechanical deformation effect of the semiconductor-based microstructure can also sense the vibration and temperature changes of the bearing. By ion implantation into the semiconductor-based microstructure to construct a microcircuit, the sensed pressure, vibration, and temperature signals are transmitted to the data acquisition system, thereby realizing real-time monitoring of the bearing performance.

[0009] (6)Furthermore, the microcircuit inside the bearing can also receive external excitation signals and act reversely on the semiconductor-based microstructure bearing surface to cause deformation, thereby controlling the bearing performance.

[0010] Compared with the prior art, the advantages of this method are as follows:

[0011] 1. Compared with the traditional bonded and reconstructed surface, we use methods such as chemical vapor deposition (CVD), chemical vapor reaction (CVR), and liquid infiltration reaction to uniformly deposit on the surface of the porous bearing, and can obtain very high bonding strength, so that the reconstructed surface will not fall off.

[0012] 2. Traditional porous bearings use graphite or ceramic materials as the bearing surface, and the surface form accuracy can only reach several micrometers, and the roughness is generally sub-micrometer. However, this patent uses semiconductor materials as the bearing surface, combined with the processing methods of semiconductor materials, to make the surface form accuracy reach sub-micrometer and the roughness less than 10 nanometers, thereby significantly improving the machining accuracy of the bearing, enabling the bearing to work in a very small air film gap, and thus obtaining extremely high stiffness, even infinite stiffness.

[0013] 3. There are a large number of irregular pores on the surface of traditional porous bearings, introducing a large amount of redundant gas, resulting in air hammer vibration when the bearing stiffness is increased, and the pore distribution is irregular and uncontrollable. In this invention, by using technologies such as LIGA, laser ablation, or soft lithography to rapidly process semiconductor materials, the pore shape on the surface can be made very regular to avoid redundant gas, and the pore distribution can be customized to obtain an ideal pressure distribution, so that the bearing hardly undergoes air hammer vibration.

[0014] 4. The traditional bearings test the service state through external or embedded sensors. Among them, the external sensors will destroy the mass distribution and change the bearing mode, and the embedded sensors will destroy the pressure distribution of the flow field. This patent uses the special piezoresistive effect of semiconductor materials to directly sense the pressure change of the bearing surface, uses the special force-thermal deformation effect of the semiconductor-based microstructure to sense the vibration and temperature of the bearing, and further extracts the sensed pressure, vibration, temperature and other signals through the microcircuit formed by ion implantation to realize real-time self-monitoring of the bearing service state.

[0015] 5. Traditional porous hydrostatic gas bearings can only be adjusted by the supply pressure. However, the strong nonlinearity of the gas leads to poor precision and very serious delay in this control method. The bearing proposed in this patent can directly introduce an external control electrical signal into the bearing by using the microcircuit formed by ion implantation, so as to adjust the microstructure of the semiconductor substrate, and cooperate with the monitored signals and intelligent algorithms to achieve real-time and precise control of the bearing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a schematic structural diagram of the designed bearing, where (1) is a comb capacitor type acceleration sensor, (2) is an annular groove for ventilation, (3) is a semiconductor layer deposited on the surface of the porous bearing, (4) is the porous bearing, (5) is an integrated thermistor, (6) is an electrical connection port, (7) is the bearing housing, (8) is a deposited thermal expansion material, and (9) is the air inlet hole of the bearing;

[0017] Figure 2 is a top view of the bearing structure, where (1) is a comb capacitor type acceleration sensor, (2) is an annular groove for ventilation, (3) is a semiconductor layer deposited on the surface of the porous bearing, (4) is the porous bearing, (5) is an integrated thermistor, (6) is an electrical connection port, (7) is the bearing housing, and (8) is a deposited thermal expansion material;

[0018] Figure 3 is a cross-sectional view of the bearing structure, where (1) is a comb capacitor type acceleration sensor, (2) is an annular groove for ventilation, (3) is a semiconductor layer deposited on the surface of the porous bearing, (4) is the porous bearing, (7) is the bearing housing, and (9) is the air inlet hole of the bearing;

[0019] Figure 4 is the manufacturing flow chart of the bearing, and its manufacturing process includes:

[0020] 1. Deposit semiconductor material on the surface of the porous bearing;

[0021] 2. Polish the surface of the semiconductor layer;

[0022] 3. Perform photolithography and grooving on the semiconductor layer;

[0023] 4. Deposit thermal expansion material on the surface of the groove;

[0024] 5. Perform surface ion implantation on the semiconductor layer;

[0025] 6. Integrate sensors on the semiconductor layer using MEMS technology.

[0026] Figure 5It is a comparison of the microscopic characteristics of a deposited semiconductor material bearing and a traditional bearing. It can be seen that there are dead zones on the surface of the traditional porous bearing, which are prone to hammer vibration, while the surface of the deposited semiconductor bearing can reach optical precision and the bearing has better performance;

[0027] Figure 6 It is a schematic diagram of the functional implementation circuit of the bearing, showing the detection and sensing functions of the bearing for pressure, temperature, and acceleration, as well as the controllability of the air permeability on the bearing surface. Specific implementation manners

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the specific implementation manners. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0029] Example 1: The ultra-precision active and intelligent porous hydrostatic gas bearing shown in this example has a core structure composed of a bearing housing, a porous material layer, and a semiconductor-based MEMS bearing surface deposited on the porous material layer as Figure 1 , Figure 2 and Figure 3 shown. Among them, (1) is a comb-tooth capacitive acceleration sensor, which is directly processed on the bearing semiconductor bearing surface using LIGA technology. The acceleration of the bearing can be obtained by connecting an external circuit; (2) is an annular groove for air permeability. This structure can control the air permeability of the bearing and improve the bearing stiffness and load-carrying capacity; (3) is a semiconductor layer deposited on the surface of the porous bearing, as Figure 4 shown, which can eliminate the dead zone of the porous bearing, avoid the phenomenon of hammer vibration, and reduce the bearing clearance, thereby improving the stability of the bearing; (4) is the porous bearing substrate; (5) is an integrated thermistor, which is directly processed on the bearing semiconductor bearing surface using LIGA technology and is connected to an external circuit through a circuit interface, and can be used to detect the temperature value on the bearing surface; (6) is the electrical connection port of the bearing, and a circuit is formed by means of ion implantation for connection with an external circuit; (7) is the bearing housing, which serves as the support structure of the entire bearing and provides the necessary mechanical strength and stability; (8) is a thermal expansion material, which can be expanded through circuit control to control the width of the air permeability groove on the bearing surface, thereby realizing the controllable air permeability of the bearing; (9) is the air inlet hole of the bearing for the input of air.

[0030] Example 2: This example introduces a processing flow of an ultra-precision active and intelligent porous hydrostatic gas bearing, as Figure 3 shown:

[0031] 1. Deposit semiconductor materials on the surface of the porous bearing by methods such as chemical vapor deposition (CVD), chemical vapor reaction (CVR), and liquid infiltration reaction. The semiconductor materials can be SiC or Si;

[0032] 2. Process the semiconductor materials on the bearing surface through mechanical grinding or chemical mechanical polishing (CMP) processes to achieve a surface shape accuracy of sub-micron level and a roughness of nano-level for the bearing;

[0033] 3. Use lithography technology to open an annular groove on the surface of the bearing deposition layer with a groove depth consistent with the thickness of the semiconductor layer to ensure the air permeability of the bearing surface;

[0034] 4. Deposit a thermal expansion material, such as a shape memory alloy, on the groove surface to control the air permeability of the groove;

[0035] 5. Perform ion implantation on the bearing surface to form a piezoresistive region. Use the piezoresistive as one arm of the Wheatstone bridge to output a differential voltage signal to obtain the pressure value on the bearing surface. In addition, it can also extend the service life of the bearing;

[0036] 6. Use LIGA technology to manufacture an ultra-precision comb-shaped capacitive acceleration sensor on the surface of the bearing. Combine with a microcircuit to measure the vibration acceleration of the bearing and achieve self-detection of the bearing state;

[0037] 7. Use MEMS manufacturing technologies such as LIGA to integrate a thermistor structure on the bearing surface and connect it to an external circuit through an electrical connection interface to measure the temperature of the bearing surface.

Claims

1. A super-precision active and intelligent porous hydrostatic gas bearing, characterized in that: It includes a bearing housing, a porous material, and a semiconductor-based MEMS bearing surface. Due to the use of a semiconductor-based MEMS bearing surface, the porous hydrostatic gas bearing can still retain a huge number of microscopic pores and maintain the air permeability of the bearing. The semiconductor-based MEMS bearing surface can take into account the sensor effect, thereby real-time sensing the performance of the porous hydrostatic gas bearing. After being acted upon by an external excitation signal, the semiconductor-based MEMS bearing surface can also change the characteristics of the microscopic pores, thereby adjusting the air permeability of the bearing and controlling the performance of the porous hydrostatic gas bearing. The perceivable and adjustable characteristics of the semiconductor-based MEMS bearing surface, combined with intelligent algorithms, enable the porous hydrostatic gas bearing to obtain automated and intelligent service capabilities.

2. The porous hydrostatic gas bearing according to claim 1, wherein the irregular pores on the porous bearing surface are sealed by depositing a layer of semiconductor material on the porous bearing surface.

3. For the surface of the blocked porous bearing according to claim 2, by thinning and polishing it, the bearing can obtain a surface with sub-micron-level accuracy, which is far superior to the surface accuracy of traditional porous bearings, thereby facilitating the bearing to obtain higher stiffness. Then, through light energy, a huge number of pre-customized pores and grooves are quickly and accurately reconstructed on the bearing surface, enabling the bearing to regain its air permeability and suspension ability.

4. For the reconstructed surface according to claim 3, by adjusting the microstructure of the reconstructed surface and combining with the thermo-mechanical deformation effect sensitive to the semiconductor microstructure, when the bearing vibrates, the air film pressure changes, and the air film temperature changes, the microstructure will correspondingly deform, and at the same time, the resistance characteristics inside the material will also change. Extracting the changes in the structure and resistance can enable the porous bearing to synchronously sense signals such as vibration, air film pressure, and air film temperature.

5. For the reconstructed surface according to claim 3, by ion implanting the semiconductor-based microstructure, precise microcircuits can be constructed in the pores and grooves. By connecting the microcircuits to an external amplifier, the signals sensed on the surface of the semiconductor-based microstructure bearing can be read, thereby enabling the bearing to have real-time self-monitoring capabilities.

6. The porous hydrostatic gas bearing according to claim 1, by receiving an external control voltage or current applied to the bearing through the microcircuit, can control the semiconductor-based microstructure on the bearing surface, thereby performing feedback control on the hydrostatic gas bearing.

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