Development Of Longitudinal-torsional Rotary Ultrasonic Vibration Grinding Device

With the widely use of various types of advanced materials(such as carbon fibre composite,ceramics)in the fields of aerospace,military,precision machinery,electronics,etc.The machining of these materials become to the key research direction of mechanical industry.Most of these materials have kinds of intractable characteristics such as high hardness,high strength,thermostability,abrasive resistance,corrosion resistance,etc.The traditional machining is difficult,inefficient,and the surface quality can't meet the requirements.Ultrasonic vibration machining is a machining method of transforming ultrasonic electric signals into mechanical vibration amplitude,which has been widely used in machining.Ultrasonic vibration machining can improve the machining efficiency and obtain good machining surface quality for all kinds of hard brittle materials.Ultrasonic grinding is a method that combines conventional grinding machining with ultrasonic vibration,which can not only improve the machining efficiency and precision,but also reduce the tool wear and tear.Studies have shown that the vibration mode of tool has a great effect on the machining efficiency and machining quality,the two-dimensional ultrasonic vibration machining can obtain better quality than the traditional one dimensional ultrasonic vibration machining.The design and analysis of longitudinal-torsional ultrasonic vibration system is the main topic in this paper.First of all,this paper reviews the current situation at home and abroad of ultrasonic vibration machining,briefly expounds ultrasonic characterization and its machining principles,and analyzes the equation of motion and the movement locus of single grain grinding.Secondly,based on the theory of acoustic propagation,a kind of ultrasonic vibration machining system is designed by the traditional analytic method.The design of ultrasonic transducer and horn is introduced in detail.And the selection of ultrasonic power supply,power transmission system,shank,tool and their conjunctive mode are determined.Thirdly,this paper introduces the familiar methods of longitudinal-torsional ultrasonic vibration machining and compares the advantages and disadvantages of them.The ultrasonic horn with diagonal slits uniformly distributed along the circumference is designed and longitudinal and torsional vibration conversion mechanism is analyzed.The effects of diagonal slits on the resonance frequency,amplitudes of longitudinal-torsional vibration are analyzed by the finite element method and the structure of diagonal slits is determined.With the movement locus of the output end is obtained by Origin,the designed ultrasonic vibration system is proved to be longitudinal-torsional ultrasonic vibration.Finally,evaluating the vibration system designed in this paper,including testing the vibration amplitude and frequency characteristic of the vibration system.Test results indicate that the resonance frequency of the vibration system is very close to the target resonance frequency.The tool end near resonant frequency amplitude test results show that amplitude under the resonant frequency is the largest,which shows that the ultrasonic vibration system design is reasonable.