Advanced Materials Research Vols. 291-294

Abstract: Through scientific experiments, we studied the binder, diamond, solder, uniform distribution and heating curves in brazing. We selected DH temporary binder, compared two kinds of diamond, selected the diamond with fine thermal stability. The experiments adopted diamond with uniform templates, experimenting 13 kinds of solder of which 9 were mixed with diamond for comparison of brazing effects and thermal damage. We optimized solder and brazing process and comprehensive analyzed experimental results. The analysis showed a small amount of DH temporary binder residue in brazing, fine effect in case of low alloy solder brazing temperature, better adhesion of solder and diamond achieved by elements formed by Cr and other strong carbides, sufficient volatilization of temporary binder and other impurities achieved by insulation before 500°C, heating rate of 1°C/min when the temperature it is higher than 20°C-50°C, the solder melting point, and that cooling should be carried out under high vacuum, brazing diamond should have fine thermal stability.

Abstract: Improvement of the service life and efficiency of trimming bits is the key to studies on metallic bond diamond saw bits. We conducted test of the preparation of layered trimming bits with different diamond and binder ingredient and sintering process with the results showing: hardness, cutting performance, strength, wear resistance and toughness of bits were improved through taking Cu as a binder phase, taking added small amount of Fe, Sn, Ni, Cr as additional binder phase to further improve the performance. After 3min insulation and sintering under 780°C, 50/60-mesh diamond hard phases are distributed on the bit alloy microscopic structure with 65Mn as the substrate. Combination of the flexible substrate and appropriately disperse hard phases achieves the improvement.

Abstract: According to the shape character of half axle bevel gear forging a process based on closed-die forging scheme was proposed. Based on a series of simulation the influence of initial forging temperature on forming force, the influence of web thickness and web position on stress, damage factor and forming force were analyzed. According to numerical analysis the web dimensions and forging temperature which ensure a minimum stress, a minimum damage factor and a proper forming load were achieved. The forming result was simulated and evaluated, and the forming load was controlled under 760ton. At last the research project got good test verifying.

Abstract: The special atmosphere of oxidation and reduction combustion in regenerative heating furnace is confirmed by anglicizing working principle of the furnace, and the growth and nature of steel’s oxide layer is influenced by the special combustion atmosphere. From the respects of thermodynamics and kinetics, the high-temperature oxidation regular of 20CrMo steel is studied. The oxidative production include steady oxide of Fe₂O₃、Fe₃O₄、FeO.The oxide layer grow slowly when temperature below 1100°C, but speedily when it is over1100°C. With the commutation of valve, the combustion atmosphere of regenerative heating furnace alternates between oxidation and reduction. Following the "intermittent" growth law, 20CrMo steel is in the process of “growth - decomposition –growth”.

Abstract: {111}∥ND forms at deformation stage, it is connected with main slip systems, by analyzing main slip systems and its performance, {111}∥ND formation mechanism can be drawn. In addition, by analyzing cold reduction’s effect on main slip systems, the relationship between {111}∥ND and cold reduction can be drawn, and some experiments can be explained.

Abstract: In the continuous cooling process, when the metal material austenite transition occurs, latent heat is released. Through the thermal-meter can determine the characteristics point of the phase transition. In this paper, by thermal analysis, at the cooling rate of 0.5°C•s^-1, 0.8°C•s^-1, 40Cr bar is tested to determine the characteristics point of the phase transition, latent heat and the heat capacity in phase transition.

Abstract: The latent heat’s releasing has effect on temperature dropping.. For example of 40Cr bar, using ANSYS finite element establish transient temperature field model in air cooling condition, and using Thermal compensation calculate latent heat can simulate cross-sectional temperature field in air cooling, obtain the temperature variation with time, this founds base for the quantitative description of the microstructure and properties of rolled steel.

Abstract: Nimonic C-263 alloy is extensively used in the field of like aerospace, power generators and heat exchangers due to its higher thermal properties. In this work, an attempt has been made to investigate the effect of the cutting parameters (cutting speed, feed rate & depth of cut) on tool wear (flank wear) in the machining of this alloy with a PVD coated carbide insert. The experiments were conducted using Taguchi’s experimental design. A second order response surface model has been established between the cutting parameters and flank wear using response surface methodology. The predicted optimal value of flank wear for coated carbide is 0.190mm. The results are confirmed by conducting verification experiments.

Abstract: This paper aimed at demonstrating advantages of a new configuring finishing hob. The features in use of the new configuring finishing hob was discussed. The advantages of the new configuring finishing hob was demonstrated. The principles that eliminate machining errors by modulating the mounting parameters, and that prolong the life span of the new configuring finishing hob were proposed. This paper is of great importance to the rationality in use, specifying tolerances, and excavating the potential of the new configuring finishing hob.

Abstract: The cutting force is the key factors influencing the processing precision and efficiency in special-shaped stone production. In this research, the cutting force is measured and analyzed in the process of special shaped cutter cutting stone. It is found that the relationship of cutting force with peripheral speed of cutter is nearly inverse proportional. The cutting force becomes smaller and smaller as the peripheral speed of cutter increases. The relationship of cutting force with feed rate is nearly proportional. The cutting force becomes larger and larger as the feed rate increases. The relationship between Fx, Fy and Fz is Fz > Fx > Fy. Enhancing the peripheral speed of cutter is a better way to increase the material removal rate.