Applied Mechanics and Materials Vols. 101-102

Abstract: At present, the trends for injection molding are higher precision, ultra-thin and light weight, and there are many harsh requirements on injected parts. For the parts manufactured by injection molding, crystallization and orientation of polymer affect the properties of the parts greatly. Crystallization and orientation affect the physical and chemical properties of the injected part, such as strength, stiffness, impact resistance, erosion resistance and so on. According to their formation mechanism, this paper presents the layout and dimensions of the coolant lines, the position, shape and dimensions of the gate, and the injection pressure etc., which play an important role for controlling the degree of crystallization and the direction and degree of orientation.

Abstract: Performance prediction of small diameter cold-rolled reinforced bar using the genetic algorithm was proposed. A mathematical model about the relationship between the parameters, which were tensile strength of small diameter cold-rolled steel rebar product and raw materials’ tensile strength, reduction of area, speed of cold-rolling and coefficient of extension, was built. The appropriate genetic parameters were determined and the data optimization of small diameter cold-rolled steel rebar’s main technological parameters was calculated. According to the optimized parameters to predict and test its performance, the experiment results are basically similar to the predicted results, and this proves that the method is effective introduction.

Abstract: The CAE simulations of filling and solidification processes for die-casting are studied. Numerical analysis is presented for a practical die-casting part using HZ CAE software. The temperature distributions and filling states in solidification and filling process are presented. Then the deficiencies of the part are predicted. Based on the analyzing results, the two die halves are modified and the die-casting parameters are adjusted. The service life of the revised die is increased from 12,000 shots to 20,000shots. It is proved that CAE simulation results can offer a helpful reference for die-casting die design.

Abstract: In order to study temperature distribution of metal powder stream in laser fabricating, its thermal radiation in visible region was detected by CCD. Based on Planck’s radiation law, the relation between molten powder temperature and its visible thermal radiation could be set up. The thermal radiation image signal of powder stream was transformed to digital signal which was used to analyzing its temperature distribution. It was shown that crosswise dimension of molten powder was about 2.5mm in diameter at the distance of 5mm from power nozzle. The powder out from powder nozzle was heated rapidly by laser. Temperature of powder in central axis regions was the highest which was nearly 2000K at the power of 1100w. The temperature gradient of powder at the edge of laser stream was greatly. The measurement results could be used to optimize the design of powder nozzle and processing parameters of laser fabricating.

Abstract: A compliant abrasive tool is investigated in this paper. By the polishing experiment of this abrasive tool, the technique of polishing the large mould free-form surface is acquired. The polishing experiments about the elastic abrasive tool are carried out, which indicates that the abrasive tool has the advantages of the high efficiency, the elasticity and compliant performance. The relation of the deflection and polishing force is investigated and it is concluded that they is approximately linearity. The effect of polishing pressure on the surface roughness is researched by experiment. Polishing quality for the edge of abrasive tool was investigated and presented. These experiment results provide significant foundation for planning polishing path and controlling process parameters to achieve good surface roughness and high efficiency in the next research.

Abstract: The process of multi-wedge cross wedge rolling is an advanced precision technology for forming long shaft parts such as automobile semi-axes. Three-dimensional solid model and the finite element model of semi-axes on automobile and dies of its cross wedge rolling were established. The process of cross wedge rolling was simulated according to the actual dimension of semi-axes on automobile utilizing the finite element method (FEM)software ANSYS/LS-DYNA. The required force parameters for designing semi-axes mill are determined. The appropriate roller width was determined according to the length and diameter of semi-axes on automobile. The results have provided the basis for the design of specific structure of automobile semi-axes cross wedge rolling mill.

Abstract: Biologically structural colors have been attracting more and more researcher’s attention and many bionics theoretical achievements of this kind may be used for surface decorating and product anti-counterfeiting. But further application has been restricted for the bottleneck problem in specimen manufacture, because of the complexity and nano-dimention of the biological structure. In this work, based on the optimized structure parameters of butterfly scales which have structural color, the specimen was manufactured using the ‘two-photon polymerization method’. Using a femto-second laser system and the photoreswast SU8 of polymer monosomic material, specimen of bionic structural color were prepared. The sample was 30×30μm. The manufacture parameters included that the laser intensity was 5.5-7mw, the distance of the adjacent points was 100nm, the exposure time was 0.6ms, and the numerical aperture of the objective lens was 1.4. The optical effects of the replication structure had been calculated with 1D photonic ‘crystal band gap’ theory. The results of the calculation showed a great consistency with natural butterfly structural color. This work is a meaningful exploration for replication of butterfly or other bionic specimens.

Abstract: This paper discusses the design of a new type fast tool servo (FTS) for precision diamond turning. The FTS has two degrees. One of them is transversal along the Z axis of lathe and the other is rotation around the Y axis. Both of the two movements are driven by electromagnetic force. The moving assembly is designed to be parallel structure for guarantying both of the two movements has similar response frequency and maximum stroke. The output force of normal electromagnetic force generated by magnetic flux bias motor has been calculated. The design of transmission mechanism has been presented. The result of acceleration calculation shows that the FTS achieves acceleration up to about 650G in both directions of movement.

Abstract: The objective of this paper is to investigate the effect of shape and size of polishing pad on the material removal characteristics in the NC polishing. The material removal model was established based on Preston equation. The law of the effect of shape and size of polishing pad on the model was simulated. Experiments were carried out. Results showed that both of the shape and size of polishing pads influence the shape of material removal curves, polishing efficiency, and surface roughness. The amount of removed material increases with the increasing of size of polishing pad.

Abstract: Cross wedge rolling of asymmetric shaft parts has a series of problems such as the difficulty of forming, and the rules of mental flow are not clear until now. Rigid plastic FE models of the asymmetric rolling and symmetric rolling were adopted to analyze the difference of the stress and strain fields of cross section and vertical section in the two rolling processes, which illuminated the rules of the stress and strain fields in the asymmetric rolling process. The research of the stress and strain fields in asymmetric rolling has positive significance for recognizing the forming characteristics and predicting deformation defects in asymmetric rolling process.