Materials Science Forum Vols. 532-533

Abstract: Geometrical model of virtual machining system was introduced. Based on the analysis of the machining system, it was divided into workpiece subsystem and tool subsystem. Dynamic models of subsystems have been established by means of simplification of machining system. Dynamic analysis and simulation have been done. Model of virtual machining system is the combination of geometrical model and dynamic model. Based on the dynamic analysis and simulation of virtual machining system, conclusion was drawn: (1) In cutting process, as cutter feeds into cutting zone, vibration appears and becomes stronger and stronger. As cutter tends to leave cutting zone, vibration becomes weaker and weaker and disappears finally. The most violent vibration occurs as cutter has engaged into cutting zone and as cutter tends to leave cutting zone. (2) As machining corresponding to dwell of indexing plate, dynamic response is smooth and steady. (3) Vibration will attenuate sharply after cutter leaving cutting zone. The operation of virtual machining system accords with the appearance in real machining process. Properties of product model are very close to those of real machined cam.

Abstract: A novel parallel machine tool(PMT) with 3-HSS structure is presented in this paper. The three ball screws and guiding-parallels of this PMT are horizontally and parallel set. The three helix joints are driving components connected to and driven by servos, and the corresponding parameters of the cutter position can be obtained. The kinematics modeling is simple and the direct and inverse kinematics can be easily obtained for this PMT. It also has other advantages, such as spacious workspace in horizon direction, simple structure, easy controlling, etc. This PMT can be used in three-dimensional carving, milling and other machining processing. This kind of PMT has been designed and manufactured in our institution, and has also been tested successfully. Besides, it’s easy to get the 5-DOF series-parallel machine tool through fixing two more revolving structure on the mobile platform. It’s also easy to furnish complex surface processing using a rotary table. This paper studies mainly on DOF analysis, derivation of the kinematical equation, direct and inverse kinematics, workspace and other kinematical problems of the parallel machine.

Abstract: The effects of the steady-state frictional heating on the contact performance of surface asperities and subsurface stress fields between rough surfaces are investigated in this paper. The asperity distortion caused by the temperature variation in a tribological process, micro plastic flow of surface asperities, and the coupled thermo-elasto-plastic behavior of the materials, with and without considering the strain-hardening property of the materials are studied. In addition, the contact pressure, real area of contact, and average gap of real rough surface with different frictional heat inputs under the thermal elasto-plastic contact conditions are analyzed and discussed.

Abstract: Part manufacturability under Concurrent Engineering (CE) environment was analyzed in detail. An evaluation system of Design For Manufacturing (DFM) was proposed according to CE ideas. The evaluation methods for part manufacturability feature-based are intended to present in this paper. Product design can be guided according to feedback information by evaluating the part manufacturability. Finally an example of rabbet-feature manufacturability of a turbine blade was given to show the method available and practicable.

Abstract: A design methodology was applied to manufacturing a tub for washing machine container. The finite element method was employed to investigate the forming process. The forming process of sheet metal into a tub for washing machine container was selected as a model process to demonstrate the design of improved process sequence which has fewer operation stages than in conventional process. The design procedures made extensive use of the finite element method which can deal with elastic-plastic modeling. A one stage process sequence to form an initial blank to final product has been simulated to obtain information on metal flow requirements. Loading simulation for conventional manufacturing process sequence has been also simulated to evaluate the design criteria. From the simulation results of conventional process sequence, it is concluded that the design criteria should include thickness uniformity in finished tub and maximum punch load within the limit of available press capacity. The newly designed sequence has two forming operations and can achieve net-shape manufacturing, while the conventional process sequence has three forming operations. The design procedure proposed in this study could be considered for the method applied to the development of process sequence design in general.

Abstract: In order to overcome the difficulties in representation of developable surfaces utilizing traditional approaches, and resolve the problems in adjusting and controlling the position and shape of developable surfaces that often faced in Engineering. In this paper, we propose a directly explicit and efficient method of computer-aided design for developable surfaces based on triangle-B spline. The shapes of developable surfaces can be adjusted using a control parameter. Meanwhile, we show that the techniques for the geometric design of developable surfaces in this paper have all the characteristics of existing approaches for curves design. The algorithms are explained in detail, and demonstrated with the examples in the paper.

Abstract: The rolling compaction can produce porous or dense strips with special functions. The mechanical behaviors in rolling compaction are hard to predict accurately and efficiently by traditional means. The numerical simulation based on the Finite Element Method (FEM) provides a flexible and efficient way for such problems. This paper introduces three-dimensional (3-D) FEM simulations for the rolling compaction of the iron matrix powders. The elliptical yield criterion, elasto-plastic constitutive relationship and the friction model were analyzed. Simulations were based on the second-developed user subroutine in MSC.Marc. Effects of friction and rolling velocity on the rolling force, distribution of the density and some other parameters were analyzed.

Abstract: The module and product family formation are the important technologies for mass customization. This paper provides a novel method of establishing the module for mass customization so that we can construct the various product families for the individuation demand. This method can obtain the driven design way of demand through the VOC (Voice of customer) report and obtain the components through the functional and structural mapping .This method accounts for the specification flow between components rather than merely the relation and similarity of the components, represents the hierarchical relations and related design constraints of the product by a structural graph and helps designers to create various product for mass customization. The methodology also is illustrated via the case study of the product family design of forklift.

Abstract: In this paper, regardless of the cooling system of the mold, the optimization design for the material distribution of heterogeneous injection mold is investigated, which is made of two base materials with different thermo-mechanical properties. A mathematical model is constructed in which both a function related to casting average temperature and the temperature gradients throughout all the cavities during the solidification process are taken as the objective function while the von Mises stress constraints of the mold are considered for reducing the stress concentration in the mold. The Finite element method (FEM) and the finite difference method (FDM) are utilized to analyze the transient heat conduction of the mold and casting. The constrained optimal design problem is solved using real coded genetic algorithm. A smooth bicubic B-spline interpolation is proposed for representing the continuous variation of material distribution. The effectiveness of the optimization results is verified by a numerical example.

Abstract: The system of customer-oriented product cooperative design(COPCD) provides a platform for customers, on which the customer designers can participate in the cooperative design activity. Through researching on the structure of cooperative design system platform based on internet/intranet, the function, which is expressed with STEP standard file and online display via network, modified as well , in the form of product model created in Pro/E, was achieved by making use of VC++6.0 programming language and OpenGL technology. Moreover, the communication tool NetMeeting was integrated in this platform interface for the communication in the process of cooperative design activities. This system platform conceptually implements the cooperation between customer and designer, the product design efficiency and its success rate would be improved.