The Study On Key Technology Of Constant Current Power System For Ultrasonic Lapping

Duo to the unique processing principle and characteristics of low processing equipment and environmental requirement, ultrasonic lapping as the main method to realize nanoscale and atomic process, has become an important part of ultraprecision machining technique. In this paper, a series of research on the excitation power supply is studied focusing on the piezoelectric transducer of ultrasonic assisted fixed abrasive lapping.During the process of ultrasonic assisted fixed abrasive lapping, the fast frequency response and power matching of piezoelectric transducer of the excitation power supply are necessary in accordance with the quick change of the load, which is an efficient approach for precision machining. In this paper, the material removal mechanism of ultrasonic assisted fixed abrasive lapping is analyzed from microscopic view. With the establishment of mechanical model of piezoelectric transducer, the relationship between equivalent impedance and load is obtained by using mechano-electrical analogy. In order to improve the stability of working conditions and surface integrity of workpiece, a method of intelligent constant current excitation power is proposed. In view of the existing transducer parameter, the design target parameter of the constant current power is determined.The design of ultrasonic lapping constant current power is divided into two parts, the hardware circuit design and the software control system design. The hardware part is mainly composed of power supply module, sinusoidal signal generate module based on DDS, power amplification module, protection and monitoring module, matching circuit module, etc. The software control part is mainly composed of DSP and CPLD. DSP is mainly responsible for providing the signal of DDS, frequency tracking and monitoring circuit, which is depend on the control of its interrupt module. And CPLD is mainly responsible for data transmission.On the basis of study, the performance test of ultrasonic lapping power is carried out. The test platform is built. The constant current output of the power in accordance with the quick change of the load and fast frequency response is verified by ultrasonic lapping test under different current and load. The design of the ultrasonic lapping constant current power is achieved the desired purpose with perfect performance. A simple contrast test between ultrasonic lapping and common lapping is completed. And the advantage of ultrasonic lapping compared with the ordinary lapping is proved. So a foundation for the development of the following process test is laid.