Papers by Author: X.J. Zhu

Abstract: Chatter easily occurs in machining, which is influenced by many factors. The power ultrasonic vibration honing equipment is taken as the research object, the dynamic friction, is studied and the dynamics model is established based on the Stribeck model and the phase trajectories and time responses are analyzed by piece-wise linear method in this paper. The results show that the system is stable and convergence rate is affected by the equivalent elastic coefficient k, the damping coefficient c and c1, the positive pressure value of N if the honing speedor. The system is critical stable and the values of k,c,Nsatisfy if or. So it should be considered that appropriately reduce the values of k, c, N when the system is designed.

Abstract: Cutting heat and the resulting temperature change material properties, thus it produces tremendous influence to cutting force, tool condition and surface roughness. The cutting heat generated by the power ultrasonic vibration cutting process were is calculated in this paper, the power ultrasonic vibration cutting is studied by using the finite element software, the conclusions are that during power ultrasonic vibration cutting, the cutting heat generated depends on the net cutting time of a vibration cycle, the rapid cooling is the main reason for lower cutting temperature in the separation stage of the workpiece and tool, and the maximum temperature of the tool is greater than conventional turning, but the average temperature of the tool is low than traditional turning.

Abstract: The power ultrasonic vibration honing is one typical method with low speed grinding precision work. Compared with traditional honing, the ultrasonic vibration honing is of the advantages such as higher precision of surface quality, small roughness, higher processing efficiency, easy to process hard crisp material, etc. In the process of power ultrasonic vibration honing, with the increased ultrasonic surging force, the grinding force becomes extremely complex and changes along with the operating condition. Its flutter belongs to the nonlinear time-variable vibration, its flutter mechanism is more complex and the harm is more serious. In order to repress the chatter phenomenon, exploring the supersonic honing chatter mechanism through the research on the grinding force's tendency change rule. Through the analysis, draws the following conclusion: the radial component, which is caused by the added ultrasonic action on the oilstone, may be possible completely or partly to counteract the dynamic grinding force caused by the thickness effect; the axial componentmay be possible to remove the cross mark’s peak effectively of the ordinary honing and enhance the surface-supporting length ratio t_p without changing the roughness; the added ultrasonic influences mutual friction between oilstone and work piece in honing process.

Abstract: Grinding chatter is a hazardous phenomenon that frequently occurred during grinding process. The topic takes radial ultrasonic vibration honing as an example to explore the dynamic changes of grinding force in ultrasonic honing process. By analyzing obtains the following conclusions: (1) The friction coefficient between work-piece and whetstone is a nonlinear time variable; (2) Adding radial ultrasonic is mainly to change the positive pressure between whetstone and work-piece, thereby affects the mutual friction between work-piece and oilstone in honing; (3) Whether ordinary honing or ultrasonic honing, friction dynamic changes along with time, performance of whetstone relative to work-piece is discontinuous sliding —jerking motion.

Abstract: Surface-supporting length ratio tp is one of the most important parameters to judge the cylinder liner’s surface quality, which has the obvious influence of on engine oil consumption, blow-by and wearing in. Effective peaks-cutted force has been studied, which is the force component of the supersonic platform honing surging force. It explained that the supersonic platform honing can combine the micro-honing and the platform honing, enhance the value of tp, which has the direct sense to the industrial practice.

Abstract: Grinding chatter belongs to non-linear vibration, whose generation mechanism is complex. The eliminating and reducing of vibration are very difficult, which have been one of the hot and difficult problems at home and abroad. Power ultrasonic vibration honing is a special processing that adds secondary ultrasonic into traditional honing. Adding ultrasound not only superimposes high-frequency vibration components on the trajectories, which makes trajectories become very complex, but also makes high frequency ultrasonic vibration elements greatly influence the vibration trajectory of chatter, which makes the stability analysis of ultrasonic honing become more complex, so it is necessary to specially study in vibration trajectories of honing process. Taking axial ultrasonic vibration honing as an example, the paper respectively takes single wear debris, two adjacent wear debris, oilstone as study object to discuss on the variation rules of honing chatter vibration trajectory after adding ultrasonic, and obtains the following conclusions: adding ultrasonic can larger vibration trajectory for single wear debris or two adjacent wear debris on microscopic scales, on the view of macroscopic which is performed as honing depth of oilstone increasing; the effects of adding ultrasonic to chatter depend on the t value; through appropriately adjusting or selecting process parameters and structural ones, chatter can be completely avoided.

Abstract: With a more application of ultrasonic technology, power-ultrasonic applied in the filed of processing about rare earth alloy and magnesium-aluminum alloy, which become more and more widespread. A steady and efficient ultrasonic vibration system is crucial, so it’s important and superior to research on the parameterization and modularization about the ultrasonic vibration system. The paper, based on the UG platform, researched and developed the modular power supersonic resonance CAE system with the using of the UG re-development tool and VC++. Finally it indicated the design method is reasonable through the confirmation of ultrasonic vibration experiment, which has a bright prospect in application.

Abstract: The contrast experiments between ultrasonic vibration honing and ordinary honing are firstly taken. It shows that the removal rates and the working accuracy of ultrasonic honing are much better than that of the ordinary honing. Then the optimum experiments on technological parameters of ultrasonic vibration honing on engine cylinder is taken, which gained the proper technological parameters. The experimental results indicate that the gained parameter totally meets the actual need and reaches a new height in this field, which provides the reliable technological parameter for the ultrasonic vibration honing to process cylinder and has a broad application in prospect.

Abstract: This paper introduces the new technology of ultrasonic vibration honing, and analyzes the cutting principle of ultrasonic honing in terms of cutting motion, grain performance and cutting quantity. Then, the applied effect used in the cast-iron cylinder of DY90 is introduced. The principle and the structure of this device are discussed. This new technology can further be used in micro-car’s cylinder, can provides a high-productivity, high-quality for cast-iron cylinder.

Abstract: In the design of ultrasonic honing equipment, it is hard to accurately get the natural vibration frequency of the ultrasonic vibration with the regular computing technology, which takes great inconvenience during designing of the device and puts it into production. This paper studies the ultrasonic vibration honing vertical equipment of φ150mm that is designed by the North University of China and carried on the natural vibration frequency analysis and corresponded numerical simulation, which got excellent achievement. In the paper the mathematical model is set up, which uses the MARC software to accomplish the numerical simulation and corresponds the vibration modal of the tool head of the devise, this paper also carries on the dynamic response analysis and solves the related difficult problem successfully. In the end, the proof test is done to support the theory.