Papers by Author: Xu Lei Yang

Abstract: Ultrasonic vibration cutting can be widely used in lathe, planer, milling machine, grinding machine, thread processing and gear processing, etc. Ultrasonic vibration cutting system is composed mainly of ultrasonic generator, ultrasonic transducer, luffing rod, cutting tool, etc. Here, ultrasonic generator is the most important. The stand or fall of signal, which is produced by ultrasonic generator, has direct influence on anticipated effect and ability of ultrasonic machining. In order to generate a signal, which can be suitable for ultrasonic machining, ultrasonic vibration cutting system is studied, and ultrasonic signal generator based on direct digital frequency synthesis (DDS) is designed and conducted a cutting test with this ultrasonic machining system. The results show that the signal generator, which is made up by DDS technology, can generate the signal with stability, reliability and greater flexibility, and can be fully applicable to the ultrasonic machining.

Abstract: In this paper, ceramic composite materials for the milling tools have been developed by the hot pressing method. High performance Al2O3/TiCN ceramic composite materials were obtained successfully by adjusting the containing amount of Al2O3 and TiCN as the base material and the reinforcements in the ceramic composite materials, and optimizing the sintering process parameters. Moreover, the microstructure and mechanical property of this material was discussed. In addition, this new developed ceramic composite material was made into insert and its milling performance tests were carried out. The machining performance of the insert is better than carbide inserts when milling a hardened carbon steel.

Abstract: It is necessary to develop complex helical drill point grinders in order to improve drilling quality and efficiency. In this paper, a new type of cutting tool grinder in which there is the tripod universal moving platform is developed, and complex helical drill grinding using the grinder is presented. In addition to complex helical drills, other cutting tools also can be ground using the grinder.

Abstract: It is necessary to develop drill point grinders in order to improve drilling quality and efficiency. In this paper, a new type of helical drill point grinder is presented. This grinder is mechanically simple, low cost and easy to be used. There are three axis simultaneous motions by means of two cams during helical drill point grinding process. Moreover, the relationships between the helical drill point parameters and helical grinding parameters are derived. As a result, the flank surfaces of helical drill points are described.

Abstract: With the raising demand of the manufacturing technology and productivity in recent year, many new type drills, such as helical drills, have been developed. However, three axis simultaneous motions of a cutting tool grinder at same time are needed when helical drill points are ground. In this paper, a biglide parallel grinder is presented. During helical drill point grinding process with this biglide parallel grinder only two axis simultaneous motions are required. Moreover, the relationships between the helical drill point parameters and helical grinding parameters are derived. As a result, the flank surfaces of helical drill points are described.

Abstract: A study of helical drill points for drilling carbon fiber reinforced plastics (CFRP) is presented. A helical drill point has an “S” contour with a radiused crown chisel that reduces the thrust force and make the drills self-centering. The S-shape chisel edge has a lower negative rake angle than a conventional chisel edge, and therefore may cut rather than extrude material. Experiments of drilling CFRP with helical drill points and conventional drill points were conducted. The results indicate that the helical drill points can reduce delamination significantly as compared to the conventional drill points under same cutting condition. Otherwise, delamination size decreases with increasing the cutting speed and increases with increasing the feed

Abstract: The prototype of a new 3-DOF tripod parallel universal wrist was developed. Its structure, characteristics and applications were introduced. The inverse kinematics model was established by the vector and kinematics influence coefficient method. The schematic diagram of simulation was established through the software — MATLAB/Simulink. Based on the above model and diagram, the inverse kinematics simulation was made. The simulation curves under different initial conditions about angle, acceleration, velocity, displacement varying as time processed can intuitively reflect the kinematic relation between the parallel bars and the moving platform of this mechanism and this is valuable and significative for the further research.

Abstract: In this paper, a Drill Point Simulation System (DPSS) which is being developed at Northeastern University is presented. By means of DPSS, the geometric models of the helical drill points were shown after inputting their design parameters. Then, the grinding parameters of the helical drill points were produced. According to the grinding parameters, the helical drill points were ground by the SD helical drill point grinder which was developed at Northeastern University. Furthermore, drilling tests were performed on aluminum sheet workpieces to investigate drilling performance of the helical drill points. In addition, the relationships between the geometric parameters of helical drill points and their grinding parameters also were derived.