Papers by Author: Jian Ping Liu

Abstract: To improve the validity and efficiency of feature recognition for 3D reconstruction from engineering drawings, this paper presents a new method of view loops separation based on multi-granularity information acquisition. By analyzing the line-frames of combined primitive views and hidden semantics in engineering drawing, combined relationship of graphics primitives can be identified, then applies line-frames partition method of figuration analysis, view loop separation of individual primitive is realized by inertial loop search with pre-set priority. This algorithm is actualized in AutoCAD 2008 platform with development tools of Object ARX2008 and Visual C#2.0. With this algorithm, an application module of 3D intelligent reconstruction system is developed and finally the validity of this research is verified by examples.

Abstract: For inverse constructing object from its orthographic image, a new method of 3D reconstruction based on image vectorization and bi-arc approximation of cubic B-spline is investigated. A 3D CAD model is automatically acquired from 2D views by means of 2D primitive recognition, 3D reconstruction of primitive and combination of 3D primitive bodies. With the help of CimatronE8.0 software, reasonable procedure design and optimization toolpath planning are applied to increase machining accuracy and productivity during automatic programming for reconstructed 3D solid. Reconstructed parts are machined on the VMC-600 type machine center with FANUC system. The results of application indicate that this method has many advantages, such as quickly obtaining the CAD model of part, getting smooth machined surface, efficient machining without invalid or reduplicate feed and so on. As a result, it can be applied widely in NC machining field.

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.