Advanced Materials Research Vols. 399-401

Abstract: Warpage makes the plastic products deviate from the shape of the mold cavity that is one of the common weaknesses of plastics. In this paper, the melt temperature, mold temperature, packing pressure and holding pressure time are chosen as the study objects, and the use of Moldflow combined with orthogonal experiment method determine the best combination of molding process parameters to obtain the minimum warpage value, which improves the quality of injection products.

Abstract: In the present paper, the effects of the hardness, strength, chemical composition, microstructure, fracture properties of the material and other factors on the chips formation and deformation were studied during cutting the brittle metal. The process of cutting the brittle metal and the basic theory of the scrap fracture was also discussed comprehensively. In addition, this study pointed out the importance of the hot working process to avoid some metallographic organizations within the cast iron such as the stripy-like and inhomogeneous graphite.

Abstract: Precipitated phase of microalloyed H beam was analysed by TEM and electrolyzation. Effect of heating temperature on austenite grain size and solid solution of Nb in steel and effect of finishing rolling temperature on property of tested steel were studied. According to the results, controlled rolling process was determined to produce the hot-rolled. Property of H beam includes that yield strength is 410MPa~430MPa, and charpy impact energy at -20°C is greater than 50J. The ferrite grain size number is 11. All of the properties are up to the American Petroleum Institute standard of H beam for offshore platforms.

Abstract: The performance of solid expandable tubular threaded joint is affected by complicated factors such as material property change, large deformation of geometric dimension and residual stress. Given material nonlinearity, geometrical nonlinearity and contact nonlinearity in the operational process of solid expandable tubular threaded joint, MSC/Marc software was adopted in this paper to conduct simulation study on the sealing property of the threaded joint during expansion and joint strength of the threaded joint after expansion. It was recognized that the solid expandable tubular threaded joint should adopt hook-shaped thread with a negative angle for the bearing surface, the sealing property of metal-to-metal cone seal would decline after expansion of the joint, and the solid expandable tubular threaded joint ought to adopt the rubber-seal-orientated sealing form. Furthermore, it was also found out that the internal thread and the root of the external thread were the vulnerable parts of the solid expandable tubular threaded joint, and the joint would first break down and cease to be effective on these parts under excessive tensile load.

Abstract: This paper introduces the software DYNAFORM which is specially used in the numerical simulation analysis of tube forming. The key components of this powerful software and the basic operating procedures are also introduced. One example of tube bending and hydroforming is simulated using this software. Based on the analyzing result, it shows that the simulation is simply and practically.

Abstract: The electrode material is playing the very important role in the electrical discharge machining. Two kinds of electrode materials common used in EDM are compared and analyses similarities and differences in structure and physical characteristics. Combined with PcBN tool machining tests, from the electric discharge machining efficiency, electrode wear, tool surface quality, tool surface degenerating layer, machining results are in analysis and comparison, and then different electrode materials machining technics in electrical discharge machining process are summarized. Through the cutting tool electric discharge machining experiments, we can know that the graphite electrode easy to take shape, suits in the complex edge's cutting tool electric discharge machining, under the same electric discharge machining parameter condition, its processing efficiency must be higher than the copper electrode, but the electrode loses, the cutting tool surface quality and affect layer thickness are to be worse than the copper electrode.

Abstract: A method of combining Gaussian Process (GP) Surrogate model and Gaussian genetic algorithm is discussed to optimize the injection molding process. GP surrogate model is constructed to map the complex non-linear relationship between process conditions and quality indexes of the injection molding parts. While the surrogate model is established, a Gaussian genetic algorithm (GGA) combined with Gaussian mutation and hybrid genetic algorithm is employed to evaluate the model to search the global optimal solutions. The example presented shows that the GGA is more effective for the process optimization of injection molding.

Abstract: Finite element model of drawing is established and numerical simulation analysis is made based on the manufacturing status of uneven thickness distribution and frequent fracture occurrence of drawing spring seat of spiral step , and regression model of the maximum thinning rate and the maximum thickening rate of the drawn workpiece is established by taking the punch radius and clearance between punch and matrix of the workpiece as influencing factors. In addition, comprehensive quality evaluation model is created via multiobjective optimization and optimal punch radius and clearance is computed. The optimization scheme is proved to be feasible and effective through experimental verification.

Abstract: Two kinds of high strength cold rolled dual-phase steel with different Si content were trial-produced in the laboratory. Tensile strength and elongation of the two steels exceed 1000MPa and 15%, respectively. The phase transformation behaviors of both steels were compared and investigated in continuous cooling process by thermal dilatometer. The effects of Si on the mechanical properties and microstructures of dual-phase steel were studied by tensile testing, OM and SEM observation. The results show that the two phase region (α+γ) is enlarged, the precipitation and growth of pro-eutectoid ferrite is promoted, and the morphology and distribution patterns of martensite are improved for high Si steel. Both steels show two-stage strain hardening characteristics. StageⅠ (ε<0.05), the solution of Si hinder the movement of dislocations, make the work hardening exponent of high Si steel is higher than that low Si steel. At stage Ⅱ (ε>0.05), the compatibility and delivery between hard phase and soft phase eliminate the differences between the two steels.

Abstract: In 3DP process, part has a large contour error due to the print machine, printing parameters, the characters of part materials and other factors. In this paper, based on the result from the Part I, the experimental method is used to study on the part contour error by placing 56 cubes in the manufacturing box in 3DP process. When the binder saturation level and the powder layer thickness are fixed, the contour error for cubes in X, Y and Z directions is obtained, and the leaking error compensation value, also means bleed compensation for the binder in different directions are achieved, and bleed compensation is used to calibrate the printer parameters. The case study also verifies the result in 3DP process, which is effectiveness in parts’ contour error compensation.