Papers by Author: Jing Lin Tong

Abstract: Ultrasonic lapping can effectively improve machining efficiency and obtain higher machining precision, which can be as the final process. This paper discusses the ultrasonic lapping mechanism through simulating the lapping tracks. Based on the contrast experiments between common and ultrasonic lapping, the influence of different lapping parameters on material removal rate and surface roughness were studied and the surface microstructure of workpiece was analyzed. The experimental results show that material removal rate of ultrasonic lapping is nearly two times that of the common lapping, especially in ultrasonic axial lapping, and the better surface quality can be obtained during ultrasonic lapping. Meanwhile, the reasons for material removal rate increasing and surface quality improving were analyzed.

Abstract: This paper researched the crack propagation and the variation of microstructure for ZTA ceramics under ultrasonic vibration grinding. To interpret the phenomenon, the nonlocal theory was introduced to establish the constitutive model under the ultrasonic vibration. Grinding experiments on surface quality of nanoZrO2 ceramic are carried out using diamond grinding in different condition, both with and without ultrasonic vibration. Experimental results show the surface quality after two-dimensional ultrasonic assisted grinding is superior to that after common grinding. Meanwhile, the effects of amplitudes and frequencies on ZrO2 ceramics crack propagation were analyzed by SEM. The results show that the crack propagation rate decrease with the amplitudes and frequencies increasing, this is because that the nonlocal attenuation ratio reduced and the nonlocal effects also the strongest. The results of experiments are in accordance with the theoretical conclusions drawn from the nonlocal theory, which verifies that the act ion of ultrasonic vibration can actually postpone the ceramic crack propagation rate.

Abstract: Carbon/carbon composite is composite material using carbon fiber as reinforcement and carbon as matrix. However, it is the difficult-to-machine material due to some characteristics of the material. The thesis uses ultrasonic milling cutting in order to improve the surface quality. Surface quality becomes better with the improvement of milling speed; surface quality becomes poor with the increases of per tooth feed and cutting depth; S_ku increases after adding ultrasonic, and which explains that the mechanism of ultrasonic milling is different from that of ordinary milling; the increase of S_al indicates that surface defects of all kinds reduces in ultrasonic milling and the surface quality is better than that of ordinary milling.

Abstract: This paper Studied the milling thickness and milling force on two directions ultrasonic vibration assisted milling. X direction ultrasonic vibration assisted milling periodic can generate periodic separation between the tool tip and the workpiece during the cutting process, so the milling force can be reduced, and the effect of the pulse cutting can be produced. Y direction ultrasonic vibration assisted milling can reduce the average cutting force, and milling width can be increased in Y direction ultrasonic vibration assisted milling, so the surface quality can be improved.

Abstract: The effects of the cutting parameters on residual stresss were investigated in common and ultrasonic vibration hard turning bearing steel GCr15 with PCBN. The residual stresses under the machined surface were measured by X-ray diffraction technique. The results obtained in this study show that residual compressive stress is produced both in common and ultrasonic turning of GCr15 bearing steel. Under the same turning condition the residual compressive produced by the ultrasonic turning is smaller than that by the common turning. Residual compressive stress can improve the fatigue performance and life of workpiece, so the cutting parameters should be optimized to get the best residual compressive stress in ultrasonic turning.

Abstract: The nonlocal theory was introduced to establish the nonlocal constitutive model and analyze the effect of ultrasonic on the tensile strength and fracture surface microstructure. ZTA ceramics tensile fracture experimental results show that the tensile stress obviously reduces and the fracture changes under ultrasonic vibration. The experimental results are coincided with theoretical analyses.

Abstract: This paper introduces the hardware and the communication software design of control system based on Controller Area Network bus. The control system can realize to control the motion of servomotor through high speed C8501F040 single chip microcomputer with Controller Area Network bus and special motion controller - LM628. This system possesses characteristics such as simple structure, high reliability and high performance/price ratio. Key words: CAN bus, LM628, Motion Control System, Communication software

Abstract: The experiment of resin-bonded CBN wheel dressing using a diamond dresser assisted with longitudinal ultrasonic vibration along the direction of depth of cut was carried out and the dressing characteristics and grinding performance were discussed in the present paper. The influence of acoustic parameters on the topography of CBN wheel was studied to check the effectiveness of dressing for this method. The experimental results showed that the higher the ultrasonic frequency is, the better the wheel topography. The grinding on K9 optical glass and high speed steel has achieved higher G-ratio than that of traditionally mechanical dressed CBN grinding wheel. The ground surface of high speed steel is better than that of K9 optical glass. According to the interferometer images, it was concluded that the grinding of high speed steel was in ductile cutting regime, while removal of K9 optical glass was in brittle fracture regime.

Abstract: The Large-grit bronze-bonded diamond grinding wheel was shaped employing a diamond dresser with elliptic ultrasonic vibration assistance, to solve problems such as high cost, low dressing speed and low accuracy. And the truing and conditioning performance of this new method was discussed for its effectiveness. Experimental results showed that the roundness error of elliptic vibration dressed diamond grinding wheel is less, and the bond tail was cut shorter and the chip capacity became larger than that of mechanical dressed one. The SEM observation showed for the present dressing method the material removal mechanism is ductile removal of bond material and micro breakup of gains and this method can perform truing of large-grit diamond grinding wheel as well as conditioning in one step.

Abstract: On the basis of analyzing the structure characteristics of the Isometric Polygonal Profile (IPP) hole, equations of the track for grinding wheel center and the formula of calculating node coordinates according to equal-error linear approximation method are established and the determination method of grinding technology parameters value and problems to be attention at grinding process are discussed. Grinding experiments show that both processing precision and surface roughness can reach with the fit requirements of IPP connection according to these principles. It is available for reference that grinding complex non-circular column surface is ground by CNC machine tools.