Newly selected, designed a new ceramic valve core pneumatic reversing valve with excellent performance, and it is feasible to apply the ceramic material to the pneumatic control valve. Conclusion 1 The valve is an important technical component in the pipe conveying system. . It is mainly used to control the pressure flow and flow direction of fluids, etc. Pneumatic reversing valves are widely used to control the direction of gas flow. In the conventional pneumatic reversing valve commonly used in the industry, there are generally defects such as poor sealing performance, easy wear of the valve core, and short service life, so that the energy loss 1 in the gas delivery system is large, and the working pressure is lowered. The output mechanism that caused the commutation is deviated. It affects the working quality of the entire output mechanism, and makes the replacement of ordinary pneumatic reversing valves frequent and the production cost increases. For this reason, it is necessary to redesign the original ordinary pneumatic reversing valve.
2 Pneumatic reversing valve use status and main defects 2.1 Pneumatic reversing 工作 working system At present, manual pneumatic reversing valves are mostly used in gas delivery systems with low working pressure. It is mainly used to control the connected cylinder pistons. Or the motion before and after, the working mechanism connected to the cylinder piston performs the prescribed action. 1 is the manual reversing valve in the pneumatic transmission, the pneumatic reversing valve 4 controls the working cylinder 5 to form a reversing working system in the pneumatic transmission, in two opposite directions of movement, which is in many manufacturing lines Can be used. Thus, the production line consists of many such working organizations. It can be seen that the amount of pneumatic reversing valve is large, and its quality of work cannot be ignored.
2.2 Defects of manual pneumatic reversing valve 1. Gas tank 2 pressure friend 3. Cut off 4. Reversing valve 5. Working cylinder out of it mainly consists of main parts such as upper cover base and valve core, and the valve core material They are made of non-ferrous metals and the bonnet and base are made of steel. In the operation of the reversing valve, the spool is rotated by the handle, so that the gas after the intake changes the flow direction and achieves the purpose of reversing. Because of the frequent rotation, it will bring the contact between the ceramic core and the bonnet. Because the core and the bonnet belong to two different materials, in the relative motion, the material with high hardness must wear and the material with low hardness is inevitably worn out. Therefore, the valve core will wear hard during work, resulting in The two contact surfaces are not tightly sealed, which causes leakage of compressed air and affects work efficiency.
Therefore, the pneumatic reversing made of the valve core material has a faster wear and a shorter service life during use. Therefore, look for teaching and research work in the material engineering machinery manufacturing technology.
Hydraulic and pneumatic types are more reliable and effective. The new pneumatic reversing valve is an important way to improve the working quality and working efficiency of gas transmission.
3 Improved design of pneumatic reversing valve 3.1 Selection of valve core material In order to solve the problem of wear and tear of different materials, the first choice should be from the selection of Shenxin Village material and the hardness phase material as the friction pair to improve the reversing valve work. The key to quality. In recent decades, the application of special Ding scale ceramic materials and machinery industry has been greatly developed. It has the advantages of small specific gravity, high hardness, high chemical stability and corrosion resistance. In some fields, it has gradually replaced gold materials. The trend. To this end, the valve core of the reversing valve can be made of this kind of engineering ceramic material with excellent performance. At the same time, it is necessary to consider that the ceramic material has a poor performance compared with the metal material, and the defect from the processing and forming is The same kind of special ceramic material is used to form the pair of friction pairs.
In the special engineering ceramic materials, 12, 3, illusion, 23 redundancy, etc. are widely used in the mechanical industry. Considering the composition of materials, processing and forming, and comprehensive performance, it is more appropriate to select people 12 and 3. The main performance of the person, 3 is 88, the bending strength is 379 river 3, the compressive strength is 2,68, and the fracture toughness is 3.4531. It can be seen that the hardness of 12, 3 is high and the compressive strength is just used. This superior characteristic makes a pair of friction pairs, and the friction pair is in operation. Mainly under pressure. Therefore, it is feasible to select 12 village materials to replace the original metal valve core material.
3.2 Core structure design After selecting the core material, it is necessary to combine the characteristics of the ceramic material. The original part is the bonnet valve core and the base. The valve core is installed in the base, and the valve core is rotated by the handle under the control. This structure cannot be adapted to the friction pair of the same material. The original valve core can be changed into two valve cores, so that the friction pair composed of special ceramic materials is composed of a fixed chip and a movable chip.
The sealing friction pair consisting of a fixed chip and a movable chip has the following advantages: good wear resistance is achieved due to the use of the same material, and the hardness of the special ceramic material is high, and their wear is small in relative motion. Because of the high compressive strength, in the work, the two-valve chip is subjected to pressure. In the case of external pressure, the two-moulder can achieve less wear and even zero wear, which can greatly improve the part of the spool. The special ceramic material has good brittleness and is difficult to process. However, the planar processing technology of domestic ceramics has matured. Many domestic manufacturers have introduced advanced processing equipment for advanced ceramic materials. Therefore, two kinds of ceramics After the chip is pressed and formed, it can be ground to a high precision, and the value of the surface roughness is very low. When the two chips are in operation, they can be tightly combined, are not easy to leak, and have good sealing performance.
Good chemical stability, special ceramic materials can work under various media, it is not easy to oxidize and corrode. In the gas transmission system, the compressed air from the air compressor often brings some oil and gas into the reversing valve, so The valve core made of ceramic material will resist the corrosion of this oil and gas. The working life of the valve core is greatly improved. 3.3 The overall improvement is designed. After replacing the original metal valve core with the ceramic valve core, the material and shape of the valve body are still The original materials and structures can be used. However, it should be considered that the ceramic valve core is in operation, the two veneers can always be kept tight and not divided. When the compressed air is just beginning to enter, the factory will be forced and high, and the gas will flow between the two contact surfaces. . At this time, a small spring can be added at the bottom of the movable chip to ensure that the lower part of the movable core is subjected to the top force of the spring, and the compressed air enters the core channel to absorb the downward pressure of the chip, so that the reversing valve is working, whether it is instantaneous. The change in pressure is still under normal working pressure, the ceramic spool can ensure close contact, and the gas is not pulled out between the two spools. In addition, the cooperation of the small spring and the bottom aperture of the movable chip is a clearance fit to ensure that the rotation of the movable chip is not affected when the reversing valve is reversed, and the reversing valve can work normally. The structure of the ceramic spool reversing valve
This kind of change consisting of ceramic core does not have good sealing performance and wear resistance, and its commutation performance is better than that of the original digital electro-hydraulic speed control system. Liu Yongjian Institute of Fluid Power Transmission and Control, Wuhan University of Technology, Wuhan 430063, Hubei Province, China 274865 Hydraulic Turbine Governor Continuous Control System The system has the advantages of simple structure, low cost and high reliability, high reliability and reliability. The turbine governor is the basic automation equipment of the hydropower station. The performance of the governor will directly affect the power quality and the safe operation of the power station. At present, most hydropower governors use a continuous control system of an electro-hydraulic servo valve pilot valve plus a main pressure regulating valve. Due to the poor resistance of the system to pollution. The guide valve of the fairy suit is prone to death and severely affects the reliability and stability of the operation of the hydroelectric generating unit. Therefore, it is an important lesson to develop a new speed control system with strong reliability against 7 souls, good stability, simple structure, easy integration and standardization, and easy technical transformation on the basis of the original speed control system. Through the research on large and medium-sized pulse width modulation electro-hydraulic governor, we propose to adopt the electromagnetic ball valve improved step type hydraulic valve to form a pulse width pulse amplitude modulation electro-hydraulic intermittent control system to replace the traditional electro-hydraulic continuous control system. .
Mainly engaged in teaching and research in electro-hydraulic control systems and hydraulic fault diagnosis.
The outlet air outlet valve is used because the surface roughness of the ceramic material can reach a lower value, the surface is smoother, and the rotation is flexible during the rotation of the valve core, so that the handle operation is also convenient, and the conclusion is that the engineering ceramic material is good. The performance application in industrial pneumatic valves not only provides a broad prospect for the application of engineering ceramic materials, but more importantly, it greatly improves the working performance of pneumatic valves, prolongs the improvement of the break, and there will be more and more in the industry. The valve uses this excellent sealing material as the valve core element, gradually replacing the original metal material, so that the performance of various pneumatic valves is improved, and the working quality of the gas pipeline conveying system is ensured.
He Cunxing, Zhang Tiehua. Hydraulic drive and pneumatic transmission elbow. Wuhan Huazhong University of Science and Technology Press. 199 Yang Yuanquan. Valve design manual. Beijing Machinery Industry Press, 3 Tong Xingsheng. Design and research of ceramic sealing chip stop valve. Mechanical system 4 was born. The performance of the work of sealing the edge of the pottery should be studied 1. Ceramic. Cheng. 1999.
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