Advanced Materials Research Vols. 538-541

Abstract: The cold-roll-formed profiles usually defects such as bow, camber, twist, edge wave, corner buckling as well as edge cracking, and splitting. Straightening is used as the later part of working procedure in order to eliminate these defects and improve the quality of the final profile. A drawing straightening machine is designed to achieve the purposes of the U-shaped steel straightening. In the design coefficient of friction, forming speed, roll speed, methods to minimize defects.

Abstract: The accuracy of the wax patterns used in the investment casting process has a direct bearing on the accuracy of the final cast part. Wax injection process plays a key role in production of nearly net shape wax pattern. Dimension shrinkage is one of the most significant problems of a wax pattern in terms of dimensional stability in the wax injection molding. This study aimed to determine the effects of injection parameters on the dimensional accuracy of the wax patterns. Linear contractions normal to flow direction and weight of wax patterns were measured and dimensional variations were evaluated. The results highlight it is important that when dealing with thick gates, short packing time appears to be the best way to avoid gate area over packing and dimensional variations, high packing pressure appears to increase expansion and dimensional variation of wax pattern.

Abstract: Based on the conception of integration and optimization of process, mechanical, electric and hydraulic system, the advanced CISDI packaged soft-reduction technology for slab continuous casting with our full intellectual property rights has been developed successfully, which consists of the metallurgical process models with strong function and advanced arithmetic, the segment equipments with optimized structure and high strength, the basic automation program with full inspection and control function, the reliable stable hydraulic system and automatic system. It contains two control modules, viz., the static soft-reduction function & dynamic soft-reduction function, and three gap-adjustment modes, viz., the position-control mode, pressure-control mode & soft-clamping mode. From the opinions of equipment protection and production safety, some functional mechanism such as segment ordinal action, gap self-adapting adjustment, forced protection for breakout prediction, and etc., have been adopted. The whole system has been put into the industrial practice on the No.6 slab caster of Liusteel China, which has shown the smooth caster operation, the steady running of system, and the good metallurgical effects on improvement of internal quality of slab like center segregation and center porosity. The industrial application of CISDI soft-reduction technology has brought the rising of output proportion of high-class steel grades and the increasing of qualified rate for slab quality inspection, which has resulted in the distinct economic benefits for Liusteel group.

Abstract: By adopting microalloying design, reasonable controlled rolling and cooling process, Pangang successful developed 600MPa grade hot rolled sheet for engineering mechanism. The average yield strength, tensile strength, elongation are 684MPa, 747MPa, 21.5%, respectively. The PQ600 steel which produced in Pangang with excellent forming property and welding property, can fully meet the requirements of users.

Abstract: In this study, the polishing machine’s mathematical model of the movement has been established by analysis the several polishing machines’ grinding and polishing process for tile. Then according to the model to simulate the trajectory and compare the grinding grain uniformity and the size of the grinding area. The results show that the disc grinding machine in improving of the efficiency of grinding and grinding grain uniformity is better than the other motions.

Abstract: Hot compression tests of the commercial Inconel 625 were performed in the temperature range of 950 - 1200 °C and strain rate range of 0.01 - 10 s-1. The constitutive relationship and the critical condition for dynamic recrystallization of Inconel 625 were established. The influence of strain on the flow stress was investigated by considering the effect of the strain on material constants. It was found that a five-order polynomial was suitable to represent the influence of the strain. The stress-strain curves obtained by the proposed constitutive equation showed a good agreement with experimental results. It can be used for the analysis problem of hot forming processes.The critical condition for dynamic recrystallization was obtained by using strain hardening rate. The critical strain increased with temperature decreasing and strain rate increasing. The critical condition for dynamic recrystallization can be expressed as .

Abstract: Surface textured tools were fabricated by laser beam machining. Dry cutting of Ti-6Al-4V alloys was carried out with these surface textured tools and conventional tools for comparison. The cutting temperature, tool flank wear and surface roughness of processed workpiece were measured. The experimental formulas of tool life based on DOT method were developed. Results show that the surface textured tool can reduce the surface roughness of workpiece, and the tool life of surface textured tool is improved by 15% or so compared with the conventional one.

Abstract: Abstract. Based on the development of blanking of steel plate in automobile industry, design features and manufacturing technology of the blanking die of thick steel plate has been described in this article. And then, according to the production, the selection of the clearance between core plate and cavity plate of the blanking die of thick steel plate has been introduced. In addition, assemblage, adjusting steps and fault treatment of blanking die of thick steel plate has been recommended, so has the breakdown types and its elimination of the blanking die of thick steel plate during the initial stage of process.

Abstract: The hot deformation behavior of Zn91.8-Cu8-Cr0.2 (in wt.%) was investigated by means of hot compression tests in the temperature range of 230-380 °C and strain rate range of 0.01 - 10 s-1. The constitutive equation and processing maps were developed. The influence of strain on the flow stress was studied by considering the effect of the strain on material constants. The stress-strain curves obtained by the constitutive equation are in good agreement with experimental results. The proposed constitutive equations can be used for the analysis problem of hot forming processes. The processing maps have exhibited a domain, which is optimum processing window for hot working, in the temperature range of 310 - 380 °C and strain rate range of 0.01-1 s-1 corresponding to the higher efficiency of power dissipation. The large regime of flow instability is observed at high strain rate. The instability regime should be avoided during hot deformation processing.

Abstract: This article describes the composition, working principle and the effect of an enviromental automatic sandblast derusting tool, and the equipment consists of air compressors, sand blasting machine, walking rack and control system. The dual-nozzle form of recycling of steel grit and rust dust using the vacuum principle, and is able to quickly complete the pipeline to fill the mouth of the sand-blasting operations. The application shows that the performance of the device is reliable, simple operation, high recovery rate of steel grit and dust, safety and environmental protection, and the rust cleaning effect reaches Sa2.5 class.