Study On Ultrasonic Assisted Finishing Process On Stainless Steel Valve Sleeve Bore

Valve sleeve, together with valve core are refer to as matching parts. The valve sleeve and core are in high precision fit. Nowadays precision matching parts are widely applied in many fields, such as aerospace from national defense field, precision machinery from industrial field, and cars, ships from transportation field. With the rapid development in aerospace and precision machinery, system’s working reliability and stability are needed to be enhanced, which means higher demand on manufacturing of precision matching parts is necessary.In order to guarantee and improve surface quality of the matching parts, finishing is adopted as the last procedure. Finishing can effectively reduce surface roughness of matching partners. Nowadays, lapping, honing and diamond reaming are mainly used for hole surface finishing. However, for small holes of high hardness material, various machining problems exist when using the above three methods.For example, in lapping, the processing time will be longer, stainless steel with high toughness characteristic leads to long lapping time and low machining efficiency; in diamond reaming process, chip that cut from the specimen is easily attached to the machining tool, which will enhance the tool’s temperature; and when honing the valve sleeve bore, stainless steel with high plasticity property will make the oilstone in machining tool blocked, which will lead to low life of honing tool, and will make it hard to guarantee hole machining accuracy and surface quality.For the problems in the above three kinds of traditional finishing processes on small-diameter stainless steel valve sleeve bore, this paper intends to combine ultrasonic vibration machining with traditional finishing process, and comes up with ultrasonic lapping and ultrasonic honing. According to the process requirements, this paper develops a set of ultrasonic vibration systemfor stainless steel small diameter hole,and vibration performance tests are conducted. Experiment of ultrasonic lapping and honing are also investigated. The research contentsof this thesis are as follows:1) A ultrasonic vibration system for small diameter hole of stainless steel material is designed, mostlyfocus on the design of the piezoelectric ceramic transducer with a sandwich structure, the integrated design of ultrasonic amplitude transformer and tool andmode analysis of the designed ultrasonic vibration system by using the finite element method. Vibration performance tests are conducted, mostly focus on two aspects:amplitude of the end face and processing surface of the tool in ultrasonic vibration system. The tool’s maximum amplitude is 15 μm, and the amplituide is stable.2) The machining performance of the developed ultrasonic vibration system is investigated.Fixed abrasive and liquid abrasive are used in lapping process, and ultrasonic lapping and traditional lapping are compared in two aspects:influence of ultrasonic amplitude and lapping time on the surface roughness and material removal rate. The results show that higher surface quality and material removal rateare acquired by ultrasonic lapping.3) New honing tool is developed on the base of the original lapping tool, oil stone and radial expanding mechanism are added to the honing tool. Ultrasonic honing and traditional honing are compared in two aspects:influences of ultrasonic amplitude and honing time on the surface quality and material removal rate. When the ultrasonic amplitude is 11μm, surface roughness reduction can reach 60% compared with traditional honing. When the ultrasonic amplitude is 15μm, material removal rate is the highest and improves 85% compared with traditional honing. The results show higher surface quality and material removal rate are obtainedand honing time are effectively reduced by ultrasonic honing, Furthermore, the performance of the developed ultrasonic vibration system is validated.