Key Engineering Materials Vols. 392-394

Abstract: Self-affine and stochastic affine transforms of R2 Iterated Function System (IFS) are investigated in this paper for manufacturing non-continuous objects in nature that exhibit fractal nature. A method for modeling and fabricating fractal bio-shapes using machining is presented. Tool path planning algorithm for numerical control machining is presented for the geometries generated by our fractal generation function. The tool path planning algorithm is implemented on a CNC machine, through executing limited number of iteration. This paper describes part of our ongoing research that attempts to break through the limitation of current CAD/CAM and CNC systems that are oriented to Euclidean geometry objects.

Abstract: The Turning-Milling may machine various complex components in once positioning and fixture with the C axis function (revolving milling). But, the vibration phenomenon of workpiece will be aggravating whether C axis is performing static cutting or continuous rotation feeding. A double-motor anti-backlash theory was applied to C axis dividing apparatus to improve the positioning and indexing accuracy of heavy NC turning-milling in this paper. The model of double-motor servo driving system with backlash was set up with mechanism analytic method. The simulation of double-motor anti-backlash was carried out. The simulation results show that the double-motor system with offset voltage has favorable performance to decrease the influence of the backlash non-linearity to the system, can guarantee the system tracks the input parameter stably, and improve dynamic feeding performance in C axis at low speed revolving. And the plant test results show that the accuracy of C axis meet practical demand.

Abstract: Variable-capacitance micromechanical accelerometer is widely used because of its high sensitivity and low power. Therefore, the further study on its performance has much theoretical and applicable significance. This paper takes the closed-loop bias stationary comb-finger variable-capacitance accelerometer as an example, introduces its operation principle, establishes its mechanics model through analysis, and gives force balance equations. Then it researches and analyzes its performances such as electrostatic forces, full scale, stability, resolution and so on. Based on the model of the parameters from the accelerometer, key expressions were acquired. These expressions reflect and affect electrostatic forces, measure range, stability, sensitivity of the accelerometer. The results prove that performance of the accelerometer are connected with the dimension of the beam, the mass, the area of the pole plate, bias voltage, feedback voltage and so on. This work will provide a reliable theoretic foundation for the further optimum design of variable-capacitance micromechanical accelerometer.

Abstract: Virtual assembly (VA) is an important application for virtual reality (VR) technology in manufacturing industries that can supply an effective solution to actual assembly problem of products. According to the assembly characteristic of large-scale products such as airplane, rocket and satellite, etc, a new interactive VA environment system is constructed, and its architecture and related key techniques are studied. Considering human free activity in the system, a free-walking perception machine is developed. And a stereo projection approach based on a video generator is proposed to enhance real-time interaction and reduce hardware cost. Finally, those key techniques are successfully applied in the process of satellite assembly planning and training.

Abstract: In picking manipulator location system, it is the key problem that the positions of obi-object and picking manipulator are exactly determined in complex environment. Based on multi-sensor information fusion method, a data fusion system of multi-sensor integrating laser-sensor for absolute location with ultrasonic-sensor for inspection impediment was presented. Firstly, data collection and fusion were implemented employing a two- level distribution system. Secondly, the method of data collection and fusion in virtual environment was discussed, and the result data could drive picking manipulator 3D model to dynamically move in real-time using event and route mechanisms provided by virtual environment, which could simulate the process of picking manipulator being accurately located. Finally, a location simulation system was developed by VC++ and EON SDK.

Abstract: This paper presents a self-organizing method for reconstruction of complex groove of milling insert. The local rule of Cellular Automata is proposed to design and optimize the groove of milling insert. The states of cells are modified according to the local rule applied. The state of the entire system is updated based on the state of the cell and its neighboring cell, and these cells’ states define the state of the entire domain, and the groove can be reconstructed. The reconstructed groove is tested by a FEM simulation. The simulation results show that the reconstructed groove has a satisfied performance on the stress field and temperature field.

Abstract: Based on the body element and topological features, studied and built up the fundamental system of feature-description of digital design and manufacturing for the typical shaft-like components, systematically researched and set up content tree of the feature description， two core sub-systems of spatial relationships of geometric elements orientated to the digital design and presentation of processing operation features faced to the digital manufacturing, followed by comprehensive-parameter method for the description of surface characteristics of the component. An example, supporting axis, from Quanhai Machinery Development Co. Ltd., was given for considerations taken in utilization of the feature-description system for the digital design and manufacturing. It is hoped that the current study and the construction of the system may lay the foundation for the unification of CAD/CAPP/CAM.

Abstract: In this paper experiments of the face grinding of Al2024/SiCp through the use of electroplated diamond wheel were carried out. The results indicated that high quality processed surface was achieved by face grinding machining, under the experiment conditions of this paper, the surface roughness was between Ra0.185 μm and Ra0.512μm, and the residual stress of processed surface was compressive stress. Grinding parameter had little effect on tangential force and normal force. Axial grinding force increased with the increasing of grinding depth and was stronger than grinding forces in other two directions.

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: This paper studies the surface quality of mould steel with high-speed wire electrical discharge machining (WEDM) method, which is conducted in gas to improve the accuracy of finish cut, and compares the surface quality in atmosphere and in emulsion dielectric. Experiment results showed that WEDM in atmosphere offers advantages such as better surface roughness and higher material removal rate. The relationship about winding speed and worktable feed on WEDMed surface quality in semi-finishing cut and finishing cut had been obtained. Morover, a new attemption was successful in applying dry WEDM in multiple cut to improve surface roughness.