Ping Zou

Experimental Investigation of Ultrasonic Vibration Assisted Turning of 304 Austenitic Stainless Steel

This research study focuses on the experimental analysis of the three-dimensional (3D) surface topography and surface roughness of the workpiece machined with ultrasonic vibration assisted turning (UAT) in comparison to conventional turning (CT). For the challenge that machining difficulties of 304 austenitic stainless steel (ASS 304) and high demands for the machined surface quality and machining precision represent, starting with cutting principle and processing technology, the ultrasonic vibration method is employed to scheme out a machining system of ultrasonic vibration assisted turning (MS-UAT). The experiments for turning the workpiece of ASS 304 are conducted with and without ultrasonic vibration using the designed MS-UAT, and then the 3D morphology evaluation parameters and are applied to characterize and analyse the machined surface. The experimental results obtained demonstrate that the process parameters in UAT of ASS 304 have obvious effect on the 3D surface topography and surface roughness of machined workpiece, and the appropriate choice of various process parameters, including ultrasonic amplitude, feed rate, depth of cut, and cutting speed, can enhance the machined surface quality efficiently to make the machining effect of UAT much better than that of CT.

Study on Ultrasonic Generator for Ultrasonically Assisted Machining

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.

Study on the Effects of the Geometrical Parameter of Twist Drill on the Drilling Performance of Stainless Steel

The key geometrical parameters of twist drills that had a great effect on the drilling performance of stainless steel were studied by Pro/E and DEFORM-3D softwares. The influence of chisel edge and tip angle of twist drill on the drilling force, torque and tool wear in the drilling process was researched, and meantime the effects were introduced by shortened the chisel edge length or adopted S-shape helical drill points as well. The tip angle of drill bit that affected the main cutting edge length, the cutting load on unit length, the proportion between cutting width and cutting thickness in the cutting lay, the cutting force, the torque, the chip formation and chip removal was introduced in detail. The choice of tip angle of twist drill was introduced. In drilling, it has important instructional significance for improvement of life of drill bit, advancement of productivity of drilling and processing quality of hole.

A New Type of Drill Grinder Based on the Special Universal Joint

This paper presents a new type of drill grinder based on a special universal joint. The special universal joint is composed of a parallel mechanism with three legs as the inputs. One can rotate as a spindle; other two legs can drive a moving platform and make a drill point get an accurate position in workspace. Due to the simple mechanical structure comparing the grinder with the existing conventional CNC cutting tool grinders, it should be easy for the grinder to manufacture at a low cost. In addition, inverse kinematic equations of the special type of universal joint are derived.

Computer Aided Design and Grinding for Helical Drill Points

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.

Comparative experimental research in turning of 304 austenitic stainless steel with and without ultrasonic vibration

The aim of this paper is to present an experimental investigation of the cutting forces, surface quality, tool wear and chip shape in ultrasonic vibration assisted turning (UAT) of 304 austenitic stainless steel (ASS 304) in comparison to conventional turning (CT). This study focuses on the solution of the machining difficulties of ASS 304 and high demands for the processing quality and efficiency. The machining system of UAT is schemed out to assure the desired machining effect by utilizing ultrasonic vibration method. Meanwhile, a series of systematic experiments are performed with and without ultrasonic vibration using the designed machining system of UAT with cemented carbide coated cutting tool. The results obtained from the UAT and CT experiments demonstrate that the cutting effect of UAT is much better than that of CT. Furthermore, the results of this research indicate that the ultrasonic amplitude, cutting speed, feed rate and depth of cut in UAT of ASS 304 have visible influence on the cutting forces, surface quality and tool wear. And reasonable selection of various technological variables in UAT can obtain lower cutting forces, more superior surface roughness, advantageous surface topography, slow and less tool wear, thin and smooth chips.

An Ultrasonic Motor Precision Adjustable Speed Scheme Study and Analysis

In this paper, the traveling wave ultrasonic motor speed regulation method, such as voltage regulators, and phase modulation characteristics，are detailed studied. Comparing the advantages and disadvantages of each, the paper put forward the reversing pulse width adjustment scheme. Experiments show that the reversing pulse width adjustment method is a good speed regulation method, the dynamic, wide speed range and good linearity governor.

Development of Al2O3/TiCN Ceramic Composite Cutting Tool and Research on its Milling Performance

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.

Research on Breaking Chip and Drilling Force for High Temperature Alloy Based on Self-Vibratory Drilling Head

Problems to evacuate chips will arise from manufacturing deep holes, especially for small diameters. Such problems induce frequent tool breakage and poor surface quality. The vibratory drilling enables the chip to be split into small elements thanks to the axial vibrations of the drill, self-maintained by the cutting energy. This research aims to improve breaking chip concerning high temperature alloy by vibraiont drilling as well as to establish a drilling technology. The development of breaking chip technology was presented. By the aid of the self-made vibrating drilling table, the axial vibration drilling was experimented on high temperature alloy with different parameter of vibration drilling. The breaking chip effect of vibration cutting was studied, and the axial drilling force and torque of vibration drilling were analyzed. The relation of each parameter and its effect on machining process was theoretically discussed. The experiment results show that vibration drilling is in favor of breaking chip, making the volume of chip small, and removing chips fluently, and the change of drilling force is relatively steady with some drilling parameters.

Study on Complex Helical Drill Grinding Using the Grinder with Tripod Parallel Universal Moving Platform

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.