Advanced Materials Research Vols. 314-316

Abstract: To form the thick-plate with the tubular bulge, the backward and forward extrusion and punch process is proposed. The thickness of sheet metal, the inner diameter of tubular bulge, the diameter of punch-die, the forward extrusion depth and other process parameters are set by orthogonal regression design method and these groups of values are used respectively to simulate the combined extruding and punching process by the plastic analysis software DEFORM3D. And then, the linear regression equation is obtained between the bulge height and process parameters. The results indicate that the main factors affecting the bulge height are the thickness of sheet metal and diameter of punch-die within a certain range. However, the inner diameter of tubular bulge and the forward extrusion depth have a little contribute to bulge height. Also, the reliability of linear regression equation is not fine and the prediction model of tubular bulge needs to a more in-depth study.

Abstract: Continuous extrusion is an advanced process for manufacturing copper bus-bar while preventing ring is an important factor affecting forming. Due to the severe plastic deformation, FE simulation of continuous extrusion extending deforming is inaccurate and inefficient because of frequent remesh. Based on finite volume method (FVM) which can avoid re-mesh effectively, this paper simulates continuous extrusion forming, and analyzes the effect of different preventing ring structure on metal flowing velocity. The results show that: preventing ring with the curve transitional surface is beneficial to metal uniform flowing than that with the plane transitional surface; As radius of preventing ring increases, the metal flow rate of the sides is faster than the middle part; As opening width of preventing ring increases, the dead metal zones become smaller in the middle area.

Abstract: In order to study the similarities and dissimilarities between creep and stress relaxation behavior of age formed aluminum alloys, both creep ageing and stress relaxation ageing experiments have been conducted with plate shaped 7055 aluminum alloy specimens on the 100 KN tensile testing machine performed at 120 °C for 20 h, under different stress levels from 190.0 to 357.8 MPa. The experimental results show that similar variation trends for creep and stress relaxation behavior were observed. Both creep and stress relaxation curves can be divided into two stages. During the first stage, higher creep rate and stress relaxation rate occur, which increase with stress levels but decrease with ageing time. While during the second stage, both the creep rate and the stress relaxation rate reach its lowest value and keep constant. A set of unified creep ageing constitutive equations has been developed and calibrated from creep experimental data, which can be used to predict the creep strain under age forming conditions perfectly. But the experimental results from stress relaxation ageing tests cannot be predicted with the established creep ageing constitutive equations, which shows that there is not a one-to-one correspondence between creep and stress relaxation, creep deformation is the most important but not the only reason for stress relaxation under age forming condition.

Abstract: The material undergoes the different deformation stage and the changing history of strain-rate and temperature affects the microstructure evolution during extrusion process. To understand the effect of extrusion process on microstructure evolution, the microstructures of aluminum profile with different wall thickness sections are compared and the variety of strain-rate and temperature are analyzed. The result show that the larger increasing gradient of strain-rate leads to the incomplete recrystallization process in thin wall section during the pocket die stage. The coarse grains are developed by second recrystallization because of the violent strain-rate changes, which is caused by the entrance of bearing-land. The lasting time of high strain-rate and temperature decided the growth of coarse grains, which is affected by bearing-land length.

Abstract: The investigation of the effect of processing parameters on forming quality has been one of the highlight researches in spinning. The thickness distribution is an important criterion to evaluate the forming quality. Spinning force affects the processing and equipment design greatly. Combining with the FEA simulation and orthogonal test method, taking the maximum reduction ratio in thickness of workpiece and the maximum spinning force as the evaluation criterion, the esequence of the main forming parameters, such as the feed rate and roundness radius of roller, and the relative height of workpiece were analyzed based on an orthogonal scheme of three-factor and three-level. Both FEA simulation and experiment results show that, during the pentagonal section hollow-part spinning, the influence sequence on the maximum reduction ratio in thickness is relative height of workpiece, feed rate and roundness radius of roller; the influence sequence on the maximum spinning force is relative height of workpiece, roundness radius of roller and feed rate.

Abstract: As-cast 30Cr2Ni4MoV steel was researched quantificationally to obtain the distribution and pattern of the microcosmic defect. By means of finite element simulation and experiment research, porosity consolidating and relative density evolution of as-cast 30Cr2Ni4MoV steel were investigated for a FM stretching process at a constant strain rate 0.001s-1. The studied parameters included three temperatures (800°C, 1000°C, 1250°C) and three deforming passes(1,2,3) and three friction factors(0.3,0.5,0.7), which bracketed the parameters that were used during most primary break-down processes. Temperature had an obvious effect on the porosity consolidating, but friction factor had no effect on the ultimate soundness nearly. When beginning temperature was 1250°C and heat exchanged considered, initial porosity can be eliminated after the accumulated effective strain reached 1.0 at least. The residual defect of the wrought material at different strain lever was compared to the initial defect of as-cast material and found to be somewhat reduced. The impact toughness of the wrought material at different strain lever was also compared to the as-cast material and found to be obvious improved. The difference in these behaviors between as-cast and wrought material could be attributed to the healing of the porosity defect and the enhancement of the soundness at a certain extent.

Abstract: The electromagnetic connection processes of Aluminum alloy pipes were studied in the paper. Experimental coil and poles were designed according to pipes’ initial size. Some electromagnetic connection experiments were carried out under gap and the number of grooves. The influences of systematic technological parameter to connection strength were investigated with tensile test. The gap of connection have a best value and less than or greater than the value will decline the connection intensity. With the numbers of grooves increasing, the growth rate of the connection intensity increased at first and then decreased. It means an optimal value. In the experiment four grooves made connection intensity an enough strength which is even greater than the material ultimate strength. Too much grooves made no sense.

Abstract: Researches and analyzes an advanced cigarettes in this paper, with the help of 3d modeling software pro/E image intuitively emulation produce its motion curves, and obtain the displacement, velocity and acceleration curve, Using the mechanism motion and kinematics analysis diagram, the mechanism kinematical process is analyzed which is laid a certain foundation for the further improved cigarette pusher device.

Abstract: The hot power spinning process of TA1 has been studied on the base of isothermal plane compression model in this paper. The microstructures of spun workpieces and plane compression specimens are analyzed and the microstructure evolution mechanism has been investigated. The results reveal that the microstructure evolution has similar mechanism between power spinning and plane compression. Plane strain compression can be used to predict and control the microstructure of as-spun TA1 workpiece.

Abstract: This paper presents a numerical method for kinematics analysis of Multi-link suspension based on displacement matrix method. A mathematical model for kinematics analysis of multi-link suspension is established and the kinematical properties of multi-link suspension are analyzed using this method. The numerical method for solving this problem is discussed and the relevant program is developed. This method simplifies the solving process of kinematics properties analysis of multi-link suspension and is efficient especially for computer-based solving process.