Study On Ultrasonic Lapping Of Precision Valve Sleeve Bore

The precision valve sleeve and the precision valve core are collectively referred to as precision matching parts, which are widely applied in the hydraulic control systems of aerospace, aviation, ships, automobiles and precision mechanical equipments, such as servo valves, hydraulic valves and so on. In view of the importance of the application and the role of the precision matching parts, the machining precision and surface quality of the valve sleeve have a significant impact on the reliability, stability and lifetime of the systems.In order to satisfy the requirements of quality and accuracy for precision valve sleeve in different application fields, generally it needs to finish the valve sleeve bore surface after grinding or boring. Nowadays, there are mainly three processes for finishing the valve sleeve bore surface in domestic, namely lapping, honing and diamond reaming. Among them, traditional lapping is most widely used. However, for9Crl8stainless steel precision valve sleeve bore with small diameter, there are different machining problems in the above three traditional finishing processes, such as low efficiency by lapping, complicated design and manufacturing of honing device, high processing temperature by diamond reaming and so on. With the increasingly manufacturing requirements of precision matching parts in different fields, the traditional finishing processes gradually cannot satisfy the needs.For the problems in traditional finishing processes on precision valve sleeve bore, this paper proposes to use ultrasonic lapping which combined the ultrasonic machining and traditional lapping to finish the surface of9Cr18stainless steel bore with small diameter. According to the process requirements, this paper develops a set of vibration system of ultrasonic lapping which is suitable for machining9Cr18stainless steel valve sleeve bore with small diameter and uses the system to conduct a series of tests for researching the processing performance of9Crl8stainless steel bore by ultrasonic lapping. The main researching work and results are as follows:1) According to the ultrasonic lapping requirements, a vibration system of ultrasonic lapping which is suitable for machining9Cr18stainless steel precision valve sleeve bore with small diameter is designed, mainly researching the design method of the sandwich piezoelectric ceramic ultrasonic transducer, the integrated design method of the ultrasonic horn-tool and the selection method of the ultrasonic generator,2) The vibration system of ultrasonic lapping is built and the vibration performance tests are carried out. This paper researches the vibration performance of the ultrasonic vibration system developed mainly through two aspects:the resonant frequency and the amplitude of the processing surface of the tool.3) The ultrasonic lapping test platform is built and the processing performance of9Cr18stainless steel bore by ultrasonic lapping is researched. This paper compares ultrasonic lapping with traditional lapping and researches the influences of ultrasonic amplitude and spindle speed on the surface quality and material removal rate. The results show that compared with traditional lapping, ultrasonic lapping can effectively improving the surface quality and material removal rate.