Papers by Author: Xiao Hui Zhang

Abstract: With the rapid development of manufacturing technology, high speed, high efficiency and high performance have been the characteristics of metal cutting. And cutting technology has been faced with a lot of opportunities and challenges. But at the same time, cutting parameter optimization has gradually been one of the most outstanding bottle-necks that restrict the rapid enhancement of cutting technology. Since the essences of cutting process, such as cutting force and temperature, are invariable, force and heat constraint are performed here to optimize milling parameters of titanium alloy. Influences of cutting edge strength and cutting temperature on milling parameters are analyzed. Finally, feasible region of milling parameters are obtained.

Abstract: With the rapid development of aviation at home, particle reinforced metal matrix composites (PRMMCs) has been widely applied recently. But at the same time, the difficult machining has gradually been one of the most outstanding bottle-necks that restrict the rapid enhancement of productivity. Here, in virtue of the self-developed ultrasonic drilling equipment, hole-making experiments of common and ultrasonic vibration drilling are performed on SiC particle reinforced aluminum-matrix composites （SiCp/Al）with different content of SiC by using two types of tungsten carbide drill. Drilling characteristics of machining composites with ultrasonic vibration are analyzed from such respects as the composites crush, drilling force, drill wear and hole surface quality. Studies show that, during the ultrasonic vibration drilling process, SiC particle in the composites is prone to break along the crystal connection boundary or suffer ductile fracture under the dynamic ultrasonic impulse, in which the cutting resistance could be reduced and the tool edge could be protected. Thereby, drilling locating precision and hole surface quality could be enhanced, wear of the drill chisel edge effectively improved, and the drilling torque reduced about 30%.

Abstract: From the definition of logarithmic spiral and its particular characteristics, logarithmic spiral is discussed and adopted as the tooth back curve of the relieving shaped milling cutter under the new manufacturing conditions. Thus, the relief angle of each point on the cutting edge keeps instant after regrinding the cutter and thereby makes for preserving the machinability stability. Besides, cutter structure parameters determine coefficient values in the equation of logarithmic spiral tooth back curve. Based on the objected-oriented thought, a CAD system for the relieving shaped milling cutter with logarithmic spiral tooth back is developed in virtue of the language of VBA embedded in AutoCAD, which achieves the automatic generation of logarithmic spiral, realizes the cutter parametric design, shortens the whole cycle and improves the design quality.

Abstract: The development of mine support equipments, which has a long history, is accompanied with the development of the coal mining industry. From its developing process, it can been seen that the developing trend of mine support equipments is from primordial to hi-tech type with characteristics of high efficiency, high speed, complete set. The developing history from the primary stage to the advanced stage has been introduced in this paper, and the further direction of the mine support equipments in China is also indicated.

Abstract: The engineblock and cylinderhead of automobile are usually made of cast iron, and tapping of blind holes is one of the most demanding operations. As usual, tapping is the final process for an engineblock, and the failure of taps can disable the engineblock possibly. The productivity is restricted because of the low cutting speed and poor wear resistance of high speed steel (HSS) taps. Thereby, according to the demand on high speed cutting and low tact time of modern engine production lines, several new typical special tungsten carbide taps are developed and their cutting performance are evaluated in comparison with the commercial taps. In the process of tapping blind holes in gray cast iron and ductile cast iron, several aspects are studied comparatively such as wear mechanism of the first complete and the last incomplete tooth, tap structure, wear of TiCN coating and effects of coolant on cutting performance of taps. This study indicates that straight coated taps with fewer flutes are suitable for high speed tapping of cast iron.

Abstract: Based on the conventional chatter stability model, stability Lobes diagram in die & mould steel milling system is obtained. The derived diagram can be divided into two independent regions by a Lobes curve: absolutely stable and instable region. In fact, it is more reasonable that there should be a transition stage between the stable and instable state. That is to say, grade of stability (GOS) should be in a closed interval [0, 1], rather than Boolean logic. Due to the different stability sensibilities for different order Lobe curve in milling system, there should be different widths of transition belts for different order curve. Thus, with the help of Sigmoid transfer function widths of each order Lobe curve are studied. Finally, the fuzzy chatter stability is implemented by an adjustable slope coefficient.