Advanced Materials Research Vols. 189-193

Abstract: Cold rotary forging is an advanced but very complex incremental metal forming technology with multi-factors coupling interactive effects. The position between the upper die and the workpiece has a significant effect on the cold rotary forging process. In the current work, a 3D elastic-plastic dynamic explicit FE model of cold rotary forging of a cylindrical workpiece is developed under the ABAQUS software environment and its validity has been verified experimentally. On the basis of this reliable 3D FE model, the effects of the position between the upper die and the workpiece on the cold rotary forging process have been thoroughly revealed. The results show that with increasing the distance between the pivot point of the upper die and the centre of the workpiece, the deformation of the workpiece becomes more inhomogeneous and the maximum axial forging force and forging moment gradually increase. The results of this research not only provide valuable guidelines for the installation and adjustment of dies in the cold rotary forging process, but also help to better understand the deformation mechanisms of cold rotary forging.

Abstract: This paper firstly analyzes the features of the spring-loaded type guide mechanism of D51 series vertical ring rolling mill. Then a reliable parametric virtual prototyping model of the guide mechanism is developed in software ADAMS. In addition, the optimal design of the guide mechanism is conducted. The minimum spring force is selected as the objective function, the dimensions of the parts of the guide mechanism are set to the design variables and the working condition is taken as the design constraints. The optimal guide mechanism is obtained after optimization, compared with the original structure, the spring force is decreased by 50.5%, and the guiding force is also decreased to a reasonable value. The research results can help to design the guide mechanism of the D51 series vertical ring rolling mill.

Abstract: During the preform design of blade body, the final forging process for blade body with different transverse cross section shapes coupled different twist angles along blade body are simulated by using DEFORM-2D finite element analysis software. The final forging quality effected by different perform structures of blade body are analyzed in details through comparing some key factors such as formability, deformation uniformity, loss of heat before deformation. The valuable references are obtained for further design of optimizing blade body shape.

Abstract: In this paper, single-pass compression test of P20 steel was carried out using thermal simulation and the experimental curves of deformation resistance were determined. Through analyzing the curves, the type of deformation resistance under practical production conditions was determined. Furthermore, the model of deformation resistance of P20 was obtained by the method of regression means, and the model precision was analyzed with the method of mathematical statistic analysis. The results indicate that the model has high accuracy in predicting precision.

Abstract: The process factors influencing the forming quality of car inner door panel such as stamping direction, binder surface, draw-bead, addendum surface and technical cut are determined based on experience knowledge. Aiming at local fracture problem of test pieces, some key parameters are determined based on experience knowledge, and the strain in thinning area of sheet metal forming is analyzed by numerical simulation. Based on this, process optimization and die modification scheme are put forward. Engineering inspection proved that optimized process and die parameters are reasonable, after increasing die fillet radius and process hole radius, decreasing draw-bead height, qualified products are achieved and fracture flaw is well controlled.

Abstract: To solve the order task allocation in Dynamic Virtual Enterprise (DVE), a multi-goal decision-making model was constructed. As to the model, an improved Particle Swarm Optimization (PSO) algorithm based order task allocation method was presented on the basis of analyzing the traditional PSO algorithm. The method overcome the deficiencies of prematurely and trapped into local optimal solution easily in traditional PSO by adjusting the parameters in algorithm automatically and introducing mutation operation from genetic algorithm. And the TOPSIS based computing method of particle fitness value was researched. Finally, the feasibility of the method was verified by an application example.

Abstract: In this paper, taking workshop scheduling of SMT product manufacture system for object, the conception of resource cost is incorporated with Petri Nets. The workshop scheduling model of SMT product manufacture system is build based on transition timed Petri Nets (TC-TPN). ω1 proportion of processing cost, ω2 proportion of processing time, ω3 mutation factor are chosen as the key factors using the improved heuristic A* scheduling algorithm. The result shows that: considering the processing time preference, when ω1=0.7, ω2=0.2, ω3 =0.1, the processing time is reduced by 5.83%, 3.45%, the processing time is decreased by 6.14% and 2.94%; however, considering the processing cost preference, when ω1=0.1, ω2=0.8, ω3 =0.1, the processing time is reduced by 1.94%, 0.86%, the processing time is decreased by 8.06% and 7.52%.

Abstract: In this paper, an indirect solid freeform fabrication (ISFF) process was developed to rapidly fabricate ceramic casting molds by combining stereolithography with gelcasting technology. To realize this method, the stereolithography apparatus was used to fabricate a resin mold, and then aqueous ceramic slurry was cast into the resin mold and in situ polymerized to form a wet green body of ceramic casting mold. Freeze drying, pyrolyzing and sintering completed the manufacturing route. Finally, the ceramic casting mold with complex ceramic cores was obtained, and a car radiator with deep grooves was produced to verify the validity and feasibility of the method.

Abstract: Based on the platform ABAQUS, 3-D FEA model for ring rolling has been constructed to investigate the effect of drive roll rotation speed on the metal flow in the ring rolling process. It can be seen clearly that the axial metal flow in the outside diameter of the rolled ring increases with the increasing of drive roll rotation speed and with the decreasing of the feeding magnitude per revolution , which causes the increasing of fishtail coefficient FT and maximum spread coefficient and in turn makes the quality deterioration of end-plane in the rolled ring. The rolling force and rolling torque necessary to execute the rolling process are reduced when the drive roll rotation speed is elevated, which results in the lower requirement for the characteristic of force and energy in the rolling machine. Besides that, average equivalent plastic strain PEEQ also increases, which indicates the enhancement of plastic deformation and is beneficial to the improvement of the mechanical property of the formed ring. But one point that we should pay attention is that uneven deformation and possibility of the inner defects in the rolled ring might be increased with the increasing of the drive roll rotation speed.

Abstract: Submarine is an important part of modern military power, and communication with submarine is a key problem which needs solving. Blue-green laser communication system with submarine can improve the safe depth and communication speed of submarine greatly, and many countries have paid a lot of attention to develop laser communication system for a long time. The disturbance would communicate in the whole system if the stray lights exit and influence the signals on detector focus surface, and these will increase the BER and influence the communication ability. This optical receiver system adopting Ritchey-Chretien(R-C) Cassegrain structure of blue-green laser communication system with submarine is introduced firstly in this paper, and then the sources of stray light are analyzed detailedly. The corresponding elimination methods for stray light are proposed and according to the analysis, the further optimization can be carried out.