Advanced Materials Research Vols. 753-755

Abstract: To obtain the effects of parameters on wall distribution homogeneity of 7075 cast aluminium alloy tube in hot power backward spinning accurately, a new method to accurately describe the wall-nonuniformity of the tube has been proposed. Combined with FE analysis, the change regularities of the wall-nonuniformity with the process parameters varying were obtained. The results show that wall-nonuniformity first increases slightly, and then decreases with the increase of preheating temperature. With roller feed rate increasing, wall-nonuniformity increases firstly, and then decreases. Furthermore, the wall-nonuniformity reaches a minimum value when the roller feed rate is 0.6mm/r. The wall-nonuniformity increases firstly, and then decreases with the increase of roller fillets radius, but the trend becomes weaker.

Abstract: To obtain the effects of parameters on elongation of 7075 cast aluminium alloy tube in hot power backward spinning accurately, a method to accurately describe the elongation of the spun tube has been proposed. Combined with the FE analysis, the change regularities of elongation with the variation of process parameters were obtained. The results show that the elongation of the spun tube increases gradually with the increase of preheating temperature, and the trend becomes larger and larger. The elongation sharply decreases firstly, and then tends to a stable value with the increase of roller feed rate. With the increase of roller fillets radius, the elongation increases gradually, but the trend becomes weaker.

Abstract: The influence cause of boron steel sheet on size precision is studied, which is contained with additional drawing stress, emergency ratio, board deep, plastic modulus, subdued point, sclerotic index, crushing force, curvature radius and so on .In order to lay the further foundations of optimizing design, it is analyzed that the latent relation of influence cause of boron steel sheet on size precision by orthogonal experiment. It is pointed orderly out that the influences with rebound result of certain automobile back wheel casing are that sheet crushing force occupies the first place, sheet thick comes second, and sclerotic index comes third, emergency ratio and curvature radius in order. It is reached that the lowest rebound condition formed of certain automobile back wheel casing drawing, the rebound way controlled is given to boron steel sheet on size precision.

Abstract: Microstructure evolution and mechanical properties of AZ91D magnesium alloys which was processed by EX-ECAP at 473K were investigated in this study. Microstructural inspection showed that the EX-ECAP was effective in refine grain size of the alloy. Tensile testing at room temperature showed that the ductility, strength and hardness of the alloy have been significantly increased by EX-ECAP. The alloy exhibited excellent superplastic properties in the form of the maximum elongation of ~218% at 473K using an initial strain rate of 3×10^-4s^-1.

Abstract: An efficient method for estimating the range of forming force for an upsetting-extruding process was proposed, which may be useful to choose appropriate forming equipment. The accurate prediction of the forming force of an upsetting-extruding process is the key to form a work piece successfully. However, the forming force is variable in a certain range for the variation of material and process parameters. In general, the variation is dominated by some of the main effects and lower-order interactions due to the sparsity-of-effect principle. Therefore, the construction of polynomial chaos expansion with points of monomial cubature rules, which need fewer points than other kinds of integral, is particularly attractive in dealing with computational model for the forming simulation. An automobile threated plate is used to illustrate the validation of the method.

Abstract: With the purpose of a uniform cooling of water convection, the horizontal nonuniform cooling on the steel plate edges should be calculated according to the site of laminar-flow water flowing nonuniformly on the top surface of strip. The result shows that the difference of water flow between the edge and centre is about 78. Sprinkle pipe with the changeable quantities of water spray can be designed to make hot strip transverse cooling close to the same.

Abstract: This paper presents the effect of forming parameters on the arithmetic mean surface roughness (Ra) of aluminum alloy built by a single-point incremental sheet metal forming process. Three investigated parameters are feed rate (12.5, 25 and 50 in/min), depth increment (0.015 and 0.030 in), and wall angle (45° and 60°). The results show that wall angle, depth increment and its interaction play an important role on the surface roughness, while feed rate has little effect. The optimal forming conditions for minimum surface roughness are feed rate of 25 in/min, depth increment of 0.015 in and wall angle of 45°.

Abstract: The composite was produced by pouring melt Al into solid Cu pipe. Microstructure, mechanical properties and Cu-Al composition distribution in Cu/Al composite interface were studied in the paper. The experimental results show that Cu and Al diffuse to each other, which the Cu/Al interface zone is formed. Moreover, there are lots of Cu-Al phase appearing in the Cu/Al interface zone. Furthermore, the influences of annealing temperature on the peal strength of Cu/Al interface were tested, in which the peel strength of the Cu/Al interface zone reaches the highest point to 15 MPa at 350°C and then decreases with the annealing temperature increases. In addition, the width of the diffusing layer and the average grain size of the Cu/Al interface zone increase with the annealing temperature increases.

Abstract: Insufficient gear tooth corner filling and high forming load are the main problems in spiral bevel gear forging. In this study, three different preforms were proposed. According to the analysis of the forging spiral bevel gear process using the semi-closed die, which was based on elastoplastic finite element model, the metal flowing law of tooth along tooth alignment and profile are revealed. From the simulation results, the arc face shape preform and the finish die with divided flow cavity are good for forging gear, and an optimized process was presented. Experiments were carried out using electric drive screw press with the rated forming load of 2500 Tons. By analyzing numerical simulations and experimental results, the process mentioned in this paper improves the tooth corner filling and reduces the forming load effectively.

Abstract: Based on the flow characteristics of resin in fiber perform, a simulation model considering distribution medium was developed, and impregnation of fiberglass reinforced resin matrix composites was numerically simulated. The fiberglass layer thickness on VIMP microscopic impregnation was analyzed in simulation. The results show that increasing fiberglass layer thickness can reduce the flow velocity of the resin and the resin flow front profile approximates a straight line type, so the fluctuation is small, and the final product has few dry spots; reducing the glass fiber layer thickness can improve wetting speed but resin flow front profile approximates a parabolic type, so the fluctuation is large, and the final product has more dry spots, the resin flow front profile can provide guidance for prediction and optimization of the infusion process.