阅读说明：本技术 一种超声电机长寿命的设计方法 (Design method for long service life of ultrasonic motor ) 是由 曹鑫鑫 汪国庆 赵盖 李兴明 宋敬伏 丁庆军 鞠沅良 王佳乐 于 2021-07-30 设计创作，主要内容包括：本发明属于超声电机结构设计领域,具体提供了一种长寿命超声电机的设计方法,将聚酰亚胺基摩擦材料由原来粘贴在转子表面转变为粘贴在定子齿上,针对超声电机摩擦界面的干摩擦的特性,利用超声波加工的方法在摩擦材料表面构筑仿生表面织构,在织构内部进行聚酰亚胺基体和固体润滑剂二硫化钼的填充,并对原来转子摩擦副表面进行相应微弧氧化处理,通过二硫化钼的填充形成三体润滑摩擦,使得超声电机表面抗摩擦磨损性能得到显著的提高,微弧氧化处理协同改进转子的硬度,能够大幅度提高超声电机的使用寿命和抗磨损性能。(The invention belongs to the field of structural design of ultrasonic motors, and particularly provides a design method of a long-life ultrasonic motor.)

1. A design method for a long-life ultrasonic motor adopts an ultrasonic processing method for a friction material adhered on a stator tooth, the texture type is a pit, the depth is 50-200 mu m, the area density is 0-20%, the distribution mode is radial distribution, and a filling material in the pit is a mixed filling material of polyimide and a solid lubricant molybdenum disulfide; and carrying out micro-arc oxidation treatment on the rotor to obtain a compact metal oxide film.

2. The friction material adhered to the stator teeth of claim 1 is a novel polyimide-based friction material; the components comprise modified fillers such as glass fiber, aluminum oxide, polyphenyl ester and the like.

3. The ultrasonic machining amplitude frequency of claim 1 is substantially between 20KHZ and 50 KHZ.

4. The pattern of dimple texture of claim 1 characterized by a predominantly circular, square, oval shape.

5. The polyimide and molybdenum disulfide mixed filler according to claim 1 is subjected to hot-pressing filler filling at 350 ℃ and under a pressure of 2.88MPa by means of high-temperature high-pressure sintering.

6. The rotor micro-arc oxidation according to claim 1 is characterized by a metal micro-arc oxidation film of 30-50 μm.

7. The friction material pack as recited in claim 2, wherein: the diameter of the glass fiber is 5 μm, the length is 20-35 μm, the particle size of the polyphenyl ester powder is 15-53 μm, and the particle size of the aluminum oxide powder is 40-80 μm.

8. The polyimide-based composite material selected according to claim 2, wherein the range of the selected polyimide-based composite material is 0.4-0.6mm, the surface of the material is sanded with metallographic abrasive paper until the roughness is less than 0.1 μm, and the material is polished with polishing cloth.

9. The type of texture described in claim 4, wherein the diameter of the circle is 0.3mm, the side length of the square is 0.2756mm, the major axis of the ellipse is 0.52mm, and the minor axis is 0.2 mm.

Technical Field

The invention belongs to the field of structural design of ultrasonic motors, and particularly relates to a design method for a long service life of an ultrasonic motor.

Background

The ultrasonic motor is a novel micro special motor which is rapidly developed in the 80 th of the 20 th century and has special application, and the ultrasonic motor has a simple structure and strong designability because the ultrasonic motor converts the micro vibration of an elastic body stator into the macro motion of a rotor through friction by utilizing the inverse piezoelectric effect. At present, the friction driving mode of the ultrasonic motor is dry friction between a stator and a rotor, the abrasion of materials is inevitable, and the service life of the ultrasonic motor is far shorter than expected due to the abrasion of the friction materials.

Patent CN201610238832.6 discloses a texture preparation method, which uses a laser processing method to etch and process the surface of a rotor friction material, but this method only aims at the bionic method which has a certain influence on the efficiency and stability of an ultrasonic motor, and does not meet the requirement for the design of a long-life ultrasonic motor.

In order to further improve the service life of the ultrasonic motor, not only a high-performance polymer friction material needs to be selected, but also a friction interface structure of the ultrasonic motor and the friction material need to be correspondingly designed. Therefore, it is very important to design an ultrasonic motor with a long service life, and the method is also an important way for improving the wear resistance and the output torque stability of the ultrasonic motor material.

Disclosure of Invention

In order to overcome the defects of the prior art, the friction interface structure is changed by adhering the friction material to the stator. The stability of a friction interface of the ultrasonic motor is improved through surface texture, the texture pits are filled with solid lubricant, the surface of the aluminum rotor is subjected to micro-arc oxidation to obtain an oxide film, the wear resistance of the ultrasonic motor is further improved, and the method is a method for prolonging the service life of the ultrasonic motor.

The invention adopts the following technical scheme for solving the technical problems:

a design for the surface texture of the stator of an ultrasonic motor is characterized in that a friction material of the stator is a polyimide composite material, the texture type is a pit, and the stator is characterized by being circular with the diameter of 0.3mm, square with the side length of 0.2756mm, oval with the major axis of 0.5mm and the minor axis of 0.2mm, the depth of 50-220 mu m and the area density of 0-20%.

A preparation method for an ultrasonic motor stator surface texture is characterized by firstly utilizing fiber filler reinforcement, a solid lubricant and a nanoparticle modification technology to prepare a thermoplastic polyimide-based composite material, wherein the surface hardness of the material is 89 (Shore hardness). Grinding the surface roughness to less than 0.1 μm by metallographic abrasive paper, polishing with polishing cloth, and slicing to 0.4-0.6mm thickness for ultrasonic processing; constructing a surface pit by using an ultrasonic processing technology, wherein the ultrasonic processing vibration frequency is 20 KHZ-50 KHZ, the speed is 100mm/s, and the cycle time is 3-5 times;

a filling method of an ultrasonic motor surface texture solid lubricant is characterized in that a mixture of polyimide and molybdenum disulfide is sintered at high temperature and high pressure at 350 ℃ and 2.88MPa, and the mixture is polished until the surface texture is exposed after sintering. And finally, adhering the polished stator friction material to the surface of the stator tooth of the ultrasonic motor for use.

A preparation method for micro-arc oxidation of the surface of an ultrasonic motor rotor is characterized in that a sodium metaaluminate alkali solution is adopted to carry out arc starting oxidation operation under the voltage of constant voltage 400V, so that a compact metal oxide film with the thickness of 30-50 mu m is obtained, and the surface hardness of the metal oxide film is 2000 (Vickers hardness). The surface roughness is polished to be less than 0.3 mu m by metallographic abrasive paper, and the polishing cloth is used for polishing treatment.

The invention has the beneficial effects that:

1. the pits processed by the ultrasonic wave have various shapes and types, uniform distribution, reliable size precision and stable friction performance.

2. After the solid lubricant and the matrix material are mixed, sintered and filled, the surface texture can effectively reduce abrasive wear of a friction interface in the operation process of the ultrasonic motor, thereby improving the operation stability of the ultrasonic motor and prolonging the service life of the ultrasonic motor.

3. The invention utilizes micro-arc oxidation to process the rotor of the ultrasonic motor, increases the wear resistance of the rotor and can prolong the service life of the ultrasonic motor.

Drawings

FIG. 1 is a topographical map and characteristic parameters of a surface microstructure according to various embodiments of the present invention.

Fig. 2 shows the location of the textured filler on the surface of the stator according to the present invention.

Detailed Description

The present invention will be described in further detail with reference to specific examples.

Example 1

The shape of the pit on the surface of the stator for the ultrasonic motor is circular, and the characteristic dimension of the pit is as follows: the pits have a diameter of 0.3mm, a depth of 100.07 μm and an area density of 9.16%.

The preparation method comprises the following specific steps:

1. firstly, slicing the polyimide composite material to 0.5mm, then utilizing metallographic abrasive paper to polish the single surface of the material until the surface roughness is less than 0.1 mu m, and polishing the polishing cloth;

2. constructing a surface pit on the friction material with the polished surface by utilizing ultrasonic processing, wherein the average frequency amplitude of the ultrasonic processing is 25KHZ, the speed is 100mm/s, and the etching cycle times are 3 times;

3. coating a layer of polyimide and molybdenum disulfide mixture on the etched stator friction material, performing high-temperature and high-pressure sintering at 360 ℃ and under the pressure of 2.88Mpa, polishing by using metallographic abrasive paper until the texture appears, and sticking the back surface of the friction material on the surface of the stator tooth for the ultrasonic motor;

4. the surface of the aluminum alloy rotor is subjected to micro-arc oxidation treatment, the aluminum alloy rotor is oxidized in sodium metaaluminate alkali liquor at constant pressure of 400V until the thickness of a metal oxide film is 46 mu m, the aluminum alloy rotor is ground by metallographic abrasive paper until the surface roughness is less than 0.3 mu m, and polishing treatment is carried out by polishing cloth.

Example 2

The shape of the concave pit on the surface of the stator for the ultrasonic motor is square, and the characteristic dimension of the concave pit is as follows: the pit side length is 0.2756mm, the depth is 92.15 mu m, and the area density is 9.16%.

The preparation method comprises the following specific steps:

1. firstly, slicing the polyimide composite material to 0.5mm, then utilizing metallographic abrasive paper to polish the single surface of the material until the surface roughness is less than 0.1 mu m, and polishing the polishing cloth;

2. constructing a surface pit on the friction material with the polished surface by utilizing ultrasonic processing, wherein the average frequency amplitude of the ultrasonic processing is 25KHZ, the speed is 100mm/s, and the etching cycle times are 3 times;

3. coating a layer of polyimide and molybdenum disulfide mixture on the etched stator friction material, performing high-temperature and high-pressure sintering at 360 ℃ and under the pressure of 2.88Mpa, polishing by using metallographic abrasive paper until the texture appears, and sticking the back surface of the friction material on the surface of the stator tooth for the ultrasonic motor;

4. the surface of the aluminum alloy rotor is subjected to micro-arc oxidation treatment, the aluminum alloy rotor is oxidized in sodium metaaluminate alkali liquor at constant pressure of 400V until the thickness of a metal oxide film is 46 mu m, the aluminum alloy rotor is ground by metallographic abrasive paper until the surface roughness is less than 0.3 mu m, and polishing treatment is carried out by polishing cloth.

Example 3

The shape of the stator surface pit for the ultrasonic motor is elliptical, and the characteristic dimension of the pit is as follows: the pits had a major axis of 0.52mm, a minor axis of 0.20mm, a depth of 215.5 μm, and an area density of 9.16%.

The preparation method comprises the following specific steps:

1. firstly, slicing the polyimide composite material to 0.5mm, then utilizing metallographic abrasive paper to polish the single surface of the material until the surface roughness is less than 0.1 mu m, and polishing the polishing cloth;

2. constructing a surface pit on the friction material with the polished surface by utilizing ultrasonic processing, wherein the average frequency amplitude of the ultrasonic processing is 25KHZ, the speed is 100mm/s, and the etching cycle times are 3 times;

3. coating a layer of polyimide and molybdenum disulfide mixture on the etched stator friction material, performing high-temperature and high-pressure sintering at 360 ℃ and under the pressure of 2.88Mpa, polishing by using metallographic abrasive paper until the texture appears, and sticking the back surface of the friction material on the surface of the stator tooth for the ultrasonic motor;

4. the surface of the aluminum alloy rotor is subjected to micro-arc oxidation treatment, the aluminum alloy rotor is oxidized in sodium metaaluminate alkali liquor at constant pressure of 400V until the thickness of a metal oxide film is 46 mu m, the aluminum alloy rotor is ground by metallographic abrasive paper until the surface roughness is less than 0.3 mu m, and polishing treatment is carried out by polishing cloth.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that it is apparent to those skilled in the art that several surface textures with different feature sizes and distributions can be made without departing from the principle of the present invention, and that the filler component in the surface texture can be changed accordingly, and such modifications should be considered as the protection scope of the present invention.