| Since the birth of double metal band saw blade, it gradually replaces the other cutting tools because of its unique advantages and has become the mainstream in the metal cutting tools industry. At the same time, with the rapid development of national economy and national basic industries increasing demand for metal cutting tools, its market in the future will be more and more broad. As the cutting to high efficiency, hardness materials, Long life, low cost and automation development direction, double metal band saw blade not only requires the tip having higher wear resistance and red hardness, but also requires back material having higher strength and good fatigue resistance matching. Therefore, to study how to improve fatigue resistance and cutting life of the back material in ultra high temperature quenching and high temperature tempering state, has important theoretical and practical significance. This article plans to do numerical simulation of induction heating and oxygen nitriding surface strengthening technology research in tempering heat treatment process of double metal band saw blade, in order to solve the double metal band saw blade’s life decreasing because of the sufficient fatigue of back material and lack of tooth abrasion resistance. Induction preheating can greatly improve the production efficiency in blade tempering process, and it found that induction heating coil size and the distance between the coil and the saw blade have great influence to the uniformity of temperature distribution. Once the distance between blade surface and the coil was determined, the heating temperature distribution was more uniform as the increasing length of the coil. The heating rate rises apparently as the distance reducing between the coil and the saw blade, and its temperature distribution was more uniform as the shorter of the coil. Once the induction heating current was in certain conditions, the thickness of the coil having a great influence on heating efficiency and temperature distribution, the smaller of coil sectional area, the higher of the heating rate, and the better of the uniformity of temperature distribution. Experimental simulation of5mm thickness coil,4mm distance between sample and the coil has higher heating efficiency and uniform temperature distribution, which is beneficial to the continuous induction preheating. Because gas-flow’s influence on oxygen nitride layer depth and the performance is not much, so the experiments used60/min ammonia drops in blade tempering process for oxygen and nitrogen. The furnace pressure for experiment was just a slightly higher than atmospheric pressure, for furnace pressure changing on the influence of nitriding layer thickness was little. Back material had good hardness at550℃×3h, and the friction and wear experiment was carried out and found that the friction coefficient was small and stable in the stable wear stage. Its wear form were oxidation wear and cutting plough wear, through the electronic probe to measure the surface of compound layer thickness, the thickness of oxide layer was about5μm, and relatively thickness of nitriding layer was only about1～2μm. Hardness of M42high-speed steel after oxygen nitriding heat treatment had been obviously increased under the process of580℃×3h and550℃×3h, especially in the550℃×3h process, its hardness was1100HV. The final550℃X3h was the best heat treatment tempering process for the oxygen and nitrogen to obtain the comprehensive mechanics performance of the saw back and the tooth. |
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