Advanced Materials Research Vols. 291-294

Abstract: In this paper, adaptive learning method of bending force presetting model in a six-high cold rolling mill is introduced. Adaptive learning coefficient of bending force presetting model is calculated by contrast between measured and model calculated actual bending force, then exponential method is used to modify the adaptive learning coefficient to improve the precision of the bending force presetting model. While calculating model calculated actual bending force, Legendre polynomials are used to convert measured flatness data to quadratic and quartic flatness coefficient, then regulating quantity on the quadratic flatness coefficient of intermediate roll bending force and work roll bending force is determined based on their regulate capability. Practical application shows that precision of the bending force presetting model has improved significantly by adaptive learning.

Abstract: A finite element method is used to simulate the deep drawing processes of nickel coating with steel substrate into battery shells. The Belytschko-Wong-Chiang shell elements are used and the kinematical work hardening model is adopted, while the ties with failure contact criterion is given to the coating and substrate interface. The stress-strain field and interfacial stresses in the drawing processes are obtained. The nickel coating appeared to be yielded in the drawing processes, of which the maximum effective stress reached 241MPa, and the biggest effective strain reached 0.7524. The interfacial stresses in the coating and substrate varied during the drawing process, and their maximal values reached 40MPa in compressive state.

Abstract: With the improvement of accuracy requirements for industrial products, the precise injection molding is replacing the traditional injection molding quickly and widely. Many factors influence the quality of injection-molded parts greatly, such as the property of the plastics, mold structure and the manufacturing accuracy, injecting machine and the injecting process parameters. In this paper, the work is emphasized for the influence of mold structure on the quality of injection-molded parts. Eight portions of injection mold are analyzed, including the cavities and cores, the guide components, the runner system, the ejection system, the side-core pulling mechanism, the temperature balance system, the venting system and the supporting parts. The structural characteristics of the above eight portions are presented.

Abstract: Cross-linked enzyme aggregates (CLEAs) of lipase from Burkholderia cepacia (BCL) were explored using different precipitants and different amount of glutaraldehyde as cross-linkers. The ‘fresh’ and ‘mature’ CLEAs-BCL was successfully encapsulated with sol-gel support. The latter showed the highest specific enzyme activity, which was 1.7 and 13.2-fold over CLEAs-BCL before encapsulation with sol-gel and free BCL, respectively. It performed high transesterification activity with the biodiesel yield of 88.5%. The ‘mature’ CLEAs-BCL presented high stability in the ranges of temperature (30-70 ºС) and pH (pH = 5-10). Scanning electron microscopy (SEM) and circular dichroism (CD) studies showed that the morph secondary structure of ‘fresh’ and ‘mature’ CLEAs-BCL was variant to some extent, which may be responsible for the catalytic activity variance.

Abstract: Using elongation model by drawing force, a dynamic tension equation is directly established. The new tension formula has the peak in the early pulling intuitively based on the velocity difference, and considering not only the surface sliding change between the rolled-piece and the roll but also the motor inertia with load.

Abstract: The wettability between pure liquid titanium and calcia-stabilized zirconia was studied in argon atmosphere. The micrographic observations made on cross section perpendicular to the interface using SEM showed that interfacial reaction occurred. However, the contact angles were larger than 90°within experimental duration.

Abstract: The influence of hydrogenation on structure and properties of TC4 alloy by die forming and sintering using hydrogenated powder was researched and the modification mechanism was analyzed by means of the room-temperature die forming and sintering in protection air to produce titanium alloy. The results show that, with the increase of hydrogen content and sintering temperature, the structure of TC4 titanium production using hydrogenated powder by die forming and sintering was changed from Widmanstaten structure to duplex structure. The density of TC4 titanium production shows a rise trend gradually. After annealing, the structure of TC4 titanium production gets more uniformity and refinement obviously, the compress yield limit shows a rising trend gradually, and the hydrogen content of TC4 alloy safety state is achieved. The density and mechanical property of TC4 titanium alloy with hydrogen content of 0.42wt % is the best.

Abstract: The hot deformation behavior of the Zn-8Cu-0.3Ti alloy was researched by compression test on Gleeble-3500 thermo-simulation machine. The results indicated that the flow stress increased rapidly with the increase of the strain at the initial stage, however, the flow stress decreased and become steady when the strain exceed a certain value. The steady stress and peak stress increased with the decrease of the deformation temperature and the increase of the strain rate. The variation regulation of the deformation activation energy and stress exponent with the strain was established through the regression method. The hot deformation constitutive relationship was also established. Comparing with the experimental results, it was proved that the model reflected the real deformation feature of Zn-8Cu-0.3Ti zinc alloy.

Abstract: Flow behavior and microstructures of GH625 superalloy were investigated by hot compression tests. Then the GH625 superalloy tube was hot extruded according to the hot deformation behavior, and the microstructures of different position of extruded tube was also analyzed. The results show that the actual deformation temperature of the specimen deformed at a strain rate of 10.0s^-1 is higher than the preset temperature, resulting in a deformation thermal effect. Thus, the microstructure evolution of GH625 superalloy is controlled both by the strain rate and deformation temperature. It is also found that the GH625 superalloy tube can be successfully fabricated with a stable extrusion speed of 40 mm·s^-1, extrusion ratio of 4.1 and preheating temperature of 1200°C. The microstructure of extruded tube was obviously fined due to the occurrence of dynamic recrystallization(DRX). Different degrees of DRX were observed in outer wall, center and inner wall of the tube, which is similar to that in the head, middle and tail of the tube. An extruded tube containing fully DRX grains can be obtained by cutting the head and tail of the tube, and machining a small amount of the inner wall.

Abstract: Based on the magnetization technological parameters optimized of sodium silicate, the properties of modified sodium silicate sand with ester hardening have been systematically investigated. The results indicated that the bonded strength of sodium silicate treated in the magnetic field may be increased by 30%~40%, the minimum addition content of sodium silicate in mold sand may reduce to 2.5%, and thus it improves markedly the collapsibility of the sodium silicate bonded sand. The used time of modified sodium silicate sand increases to 25%, but the effect of magnetization of sodium silicate will be disappeared after 24 hours, and the magnetization decaying speed enhanced with increasing the modulus of sodium silicate. The magnetization modification has a good effect on the high modulus sodium silicate than the low modulus sodium silicate.