Papers by Author: Xue Zhi Zhao

Abstract: In this paper, Finite Element Technology is applied to study the vibration state of violin sounding box using numerical simulation. By means of geometric modeling for the complicated shape of violin sounding box and Finite Element Analysis, the structural parameters of violin box, including thickness of violin plate, height and distribution and change of the shape of arch in front plate geometry, status of bass bar and sound-post etc, are investigated for their influence on vibration patterns and frequency response of violin box. Experiment is carried out for measuring the frequencies responses of violin box to verify the results of the Finite Element Analysis. This research provides a feasible way of theories for violin makers to improve the vibration characteristics of violin.

Abstract: The import mechanical components and burden part in aeronautic and automobile industry, such as screw shaft, aero-bearing and engine vane etc. are often found fatigue failure cased by their residual stress state on machined surface. Aiming at the problem, this paper presents a new green machining technology by integrating pre-stress cutting and hard machining method. The principle of pre-stress hard cutting of shaft part is introduced together with its implementary process in this paper. Pre-stress loading method on screw shaft is investigated and device for actualizing the process is designed. Experiment of pre-stress hard cutting is carried out for screw shaft with PCBN tool. The experimental results show that by using this method, residual compressive stress is got on machined surface and hence increase the quality and fatigue life of screw shaft.

Abstract: In this paper, we investigate the relationship of heating current in Electric Hot Machining with tool life, cutting parameters and machined surface roughness. Experimental results indicate that there is an optimal heating current in EMH in which the effect of hot machining is the best. A method of rapid determining the optimal heating current under various cutting conditions in EHM is proposed according to the conservation law of optimum cutting temperature. That is, for a certain combination of tool and workpiece, the heating current relative to optimal cutting temperature in different conditions can be found by changing heating current and measuring cutting temperature to meet the control object of temperature in EHM. The PID control principle and effect of computer monitoring system for realizing optimal heating current control in EHM is also introduced.

Abstract: For detecting gradual tool wear state on line, the methods of Wavelet Fuzzy Neural Network, Regression Neural Network and Sample Classification Fuzzy Neural Network by detecting cutting force, motor power of machine tool and AE signal respectively are presented. Although these methods are not difficult to come true and processed accurately and rapidly, it is difficult to obtain comprehensive information of machining and exact value of tool wear when using single method of intelligent modeling and single signal detecting. For this purpose, fuzzy inference technique is adopted to fuse the recognized data. Emulation experiment is carried out by using Matlab software platform and this method is verified to be feasible. Experimental result indicates that by applying fuzzy data fusion, we can get an exact tool wear forecast rapidly.

Abstract: Theoretical analysis and experiments on bearing race show that a suitable residual compressive stress on roll path of bearing race can prolong its contact fatigue life. However, residual tensile stress is often found on workpiece surface of bearing race. To actively control the residual stress state and improve fatigue life of bearing part, a new method of pre-stress hard cutting is applied. In this paper, the principle of pre-stress hard cutting for bearing race is introduced as well as the experiments on it. In the experiments, residual stress, hardness and roughness of machined surface are measured and analyzed. Moreover, micro-topography and texture characteristics of machined surface are investigated and experimental results are compared with that by grinding. It is found that we can get residual compressive stress and fine quality on machined surface of bearing race by pre-stress hard cutting and increase its productivity as well.

Abstract: The analysis on load characteristics and stress state of bearing races shows that the roll path and outside layer of a bearing race are the main part to bear the load, and that residual tensile stress is often found on workpiece surface. For the purpose of improving residual stress state on machined surface of a bearing race, a method of pre-stress hard cutting is put forward. In this paper, the principle of pre-stress cutting is introduced, and method of loading stress on bearing races, together with the calculation for pre-stress, is analyzed. A set of device with expanding mandrel for realizing the process is designed too and an experiment of pre-stress cutting is carried out on a lathe with PCBN tool. The experimental results show that, by using this method, we can get residual compressive stress on machined surface layer of a bearing race and increase the quality and contact fatigue life of bearing.

Abstract: Gearlike cylindrical structure can be used as outer ring of linear bearing for saving material, but the machined surface quality and roundness of this kind of bearing is beyond control in cylindrical grinding and machining efficiency is low. To solve these problems, a new method of pre-stress grinding for gearlike cylindrical surface of linear bearing is put forward based on analysis on the principle of cylindrical centerless grinding. For implementing this process, a set of device with expanding mandrel for loading tensile pre-stress on bearing ring is designed and experiment of through-feed grinding is carried out on centerless grinder. The experimental results show that this method can get fine quality of machined surface and increase the grinding efficiency greatly.