Advanced Materials Research Vols. 139-141

Abstract: Feature-modeling has reached the design mainstream, which was considered as one of ways to integrated system unblocked. Discussing the definition and classification of feature and giving the contents of features of management information, features of technical information and form features, then the part information model was established based on the features in the paper. The systems of treelike part classification coding and feature coding take an important part in the model, which were described based on structural and technological characters of injection parts. Under the rules of feature coding, the feature codes for sprue bush and B plate were developed. The part information model is used to describe, obtain, store, and transmit the part information of the integrated system.

Abstract: Cutter trace calculation and interference checking play a dominant role in the NC machining of complex surface. In this paper the conceptions of the final movement and the orientation-distance have been proposed. It is proved that the two points with minimal orientation-distance on a pair of smooth surfaces are conjugate points. Thus the conjugate problem between the two surfaces is converted into optimization process of orientation-distance function. Combining minimal orientation-distance principle with five-point optimization method, the minimal orientation-distance algorithm has been proposed to calculate the cutter trace. The cutter trace and the cutter interference are achieved respectively by local and global optimization of the orientation-distance function based on the minimal orientation-distance algorithm and GA. The validity of this new algorithm is also proved by helicoids NC machining.

Abstract: The article introduces the advantages and the application of the visual design, analyzes the tendency and shortage of product development about high pressure valve used in wellhead. Combining the visual design method with collaborative design idea, a visual design system is designed for high pressure valve used in wellhead, which includes three modules. The development process and function of the system is described in detail. Based on a great deal database and modularized collaborative design, basic geometric design, three-dimensional modeling, virtual assembly and finite element analysis (FEA) on chief parts are finished successfully. Practice indicated that the visual design system was an effective measure to improve efficiency of design, meet the demand of the development of product serialization, and reduce the cycle of development of product, reduce the cost.

Abstract: In order to raise ability of five-axis CNC machine tools to machine geometrically complex work pieces efficiently and with higher dimensional accuracy, it is necessary to research its mechanical eigenfrequency of mechanical transmission system. A multi-body modeling method for the vibration analyze of ball screw drive system is presented in this paper. To design such a structure properly, an analysis model for the multi-body system needs to be developed to estimate the modal characteristics effectively and properly; the transfer matrix method for the solution of the eigenfrequency problems of ball screw drive system for CNC machine is considered here. The vector–matrix formulizers of motion of multi-body system for this system are given. By using transfer matrix method, the global dynamics equation is not needed in the study of multi-body system dynamics, and it has advantages of a small size of matrix and higher computational speed.

Abstract: In order to solve the deformation of thin-walled parts when fixed by fixtures in the environment of examination, transport, welding, assembly and demonstration, the paper is based on automatic planning approach of main champing points in Rapid Fixture Design System and mainly focuses on auto-planning auxiliary clamping points of thin-walled parts in Rapid Fixture Design System and represents the layout of auxiliary clamping points to deal with the problem of easy deformation of thin-wall parts when under small stress environment, which establishes automatic planning approach of RP. Finally, the paper gives an example to verify the effectiveness of the approach. Achieve the goal of designing rapid fixture automatically, fast and efficiently and enhance the capacity of enterprises responding quickly to dynamic changes in the market.

Abstract: Currently, manual inspection and off-line inspection play an important role in the inspection methods of machining process, which severely restricts the development of inspecting automation. In the paper, automatic programming system for machining center on-line inspection was developed by secondary development kit object ARX of AutoCAD. Inspecting datum was obtained, inspecting process planning was laid up and inspecting program was made automatically. The inspection can be applied to automatic workpiece setting up, on-line inspection of workpiece, data processing, quality analysis and compensation of machined workpiece errors, which led to increase precision, production efficiency and quality and reduced the rate of rejection and tool damage.

Abstract: Basic research on five-axis NC machining of subdivision surface is presented. Research on Catmull-Clark subdivision surface, a method is presented by using computational geometry techniques to determine optimal tool position and orientation for 5-axis machining with torus end-mill: The normal vector of the subdivision surface vertex and the offset surface calculation are discussed firstly, then the rough machining model of subdivision surface is built and machined by using five-axis machining with the motion of the torus end-mill position and orientation according to the normal line of the surface. The tool position and orientation, cutting radius and tool path are calculated. Finally a computer simulation instantiation is given. This method improves the machining ability of subdivision surfaces.

Abstract: To improve the maxillofacial surgery outcome, modern manufacturing methods such as rapid prototyping (RP), reverse engineering (RE) and medical imaging data have been utilised to manufacture custom-made prostheses after previous failed reconstructive surgery. After acquisition of data, an individual computer-based 3D model of the bony defect was generated and transferred into RE software to create the prosthesis CAD model. Then the physical model of the prosthesis was fabricated by RP technique. The precise fit of the prosthesis was evaluated using the prosthesis and skull models. The prosthesis was then directly used in investment casting such as “Quick Cast” pattern to produce the titanium model. In the clinical reports presented here, reconstructions of one patient with large mandible bone defects were performed using this method. The custom prostheses perfectly fit the defects during the operations, and surgery time was reduced. These cases showed that the prefabrication of a prosthesis using modern manufacturing technology is an effective method for maxillofacial defect reconstruction.

Abstract: By defining analysis feature and using analysis results to drive the parametric model, behavioral modeling establishes feature parameter of model automatically for meeting design objectives and making model technology intelligent, that is to say the result could be optimized automatically. In this paper, the application of PRO/E parametric modeling technologies in design of cam profile curve is researched. In order to optimization for dynamic balance of the cam, the methods of defining analysis feature and sensitivity/optimization analysis are proposed by using the technology of PRO/E behavioral modeling. These technologies can enhance the efficiency and quality of the cam design and provide a practical method for 3D modeling of this kind of cam. The fifth generation of CAD model technology named behavioral modeling provides the method of flexible and intelligent solution of practical engineering problems.

Abstract: Structure design of a product under complex loads not only must meet the conditions of its strength and stiffness, but also must consider the requirements of its fatigue life. Due to the lack of historical data of actual loads and stress, it is usually difficult to predict the fatigue life of product structure in life-customized design. Taking self-propelled steel bridge as an example, which is used for spoil transportation of tunnel construction in the Beijing-Shanghai high-speed railway projects, this paper presents a method of fatigue analysis for product structure for life-customized design. The approach of this work includes steps of (1) simulating actual work and load conditions of the bridge based on finite-element (FE) method, and determining risk components of the bridge, (2) analyzing the stress time history of dangerous components of the bridge, and drawing out the stress spectrum to solve the bottleneck problem of fatigue life calculation in the bridge design, (3) correcting the material S-N curves and predicting the fatigue life of the bridge based on Miner linear cumulative damage theory. The results of this research will facilitate implementation of life-customized design, thus meet the requirements of expected life of the bridge, and also improve the reliability and security of the bridge in engineering application.