The Applied Research of Cryogenic Metalworking

本文研究了低温金属加工技术在金属板料加工、拉丝和轧制中的应用，包括金属的冷却和输送条件、模具的材料和结构、加工后的后处理等.钣金加工实验采用10吨液压机。将0.5mm厚的纯铝和耐蚀铝合金板在液氮温度下冷却后，利用传递模架在50 mm的间隔内进行深冷胀形。通过对金属加工前后温度变化的理论和实验分析，阐明了最合适的模具结构是液氮冷却和液氮吹胀相结合的模具结构。SUS 304对模具材料很有用。拉丝实验采用纯铜和几种铜合金进行拉丝实验.由于冰的润滑作用，低温拉丝的摩擦系数约为室温拉丝的1/2-1/3。冷拉丝带来约10 kgf的强化。<mm^（-2）>。这可以用位错的增加和细胞结构的形成来解释。对于沉淀型合金，这对于降低沉淀温度是有用的.板材轧制采用纯铝、耐蚀铝合金板材，在小型二辊轧机上进行轧制试验。通过测量滚动载荷和前滑量计算摩擦系数的变化。与室温轧制板相比，冷轧板的强度提高了10%左右。这可以用位错的增加和细胞结构的形成来解释。

In applying the cryogenic metalworking to sheet metalworking, wire drawing and sheet rolling, the surrounding apparatus and technology; namely the cooling and carrying conditions of metal, the material and construction of die set, the post-treatment of worked products, etc; are investigated here.1. Sheet metalworkingThe hydraulic press machine having the capacity of 10 ton is used for the experiment. After cooling pure aluminium and corrosion-resistance aluminium alloy sheets of 0.5mm in thickness at the temperature of liquid nitrogen (LN), cryogenic bulging is carried out in the interval of 50 mm using transfer die set. By analysing the change of temperature before and after metalworking, theoretically and experimentally, it is clarified that the most appropriate structure of die set is the combination of die cooling by LN and blowing-up of LN. SUS 304 is useful for die material.2. Wire drawingPure copper and some kinds of copper alloys are used for wire drawing experiment. Frictional coefficient in cryogenic wire drawing is 1/2-1/3 of that in room temperature drawing, as a result of ice lubrication. Cryogenically drawn wires bring the strengthening of about 10 kgf. <mm^(-2)> in comparing with the strength of room-temperature drawn wires. This can be explained by the increase of dislocation and the formation of fine cell structure. For precipitation type alloys, this is useful for decreasing the precipitation temperature.3. Sheet rollingPure aluminium, corrosion-resistance aluminium alloy sheets are used for rolling experiment in using small 2 high mill. The change of frictional coefficient is calculated by measuring rolling load and forward slip. Cryogenically rolled sheets bring the strengthening of about 10% in comparing with the strength of room-temperature rolled sheets. This can be explained by the increase of dislocation and the formation of fine cell structure.