| Mold is an important craft equipment in industrial production. In modernization industrial production, the mold has become more and more important in manufacturing industry in order to increase the productivity and guarantee the product quality. At the same time, the mold industry must unceasingly to raise its own technical level in order to meet the development demand of industry.High-speed milling, one of the hottest fields in the current numerical control technology of machining, is used more and more to process the hard-cutting materials (such as hardened steel, graphite and titanium alloy) because it's many kinds of superiority which have been demonstrated in the practical application. In the mold manufacturing industry, high speed milling is mainly applied to machine the hardened steel mold, the EDM electrode and make a specimen fast. However, the cutting tool fast attrition and break appear often when machine the hardened steel owing to its high hardness and big intensity. This situation will damage the work piece, low the efficiency and cannot achieve the anticipated effect. One of the reasons appears in above situation, is the unreasonable choice of craft parameter. Therefore it has a practical meaning to optimize the technological parameters in high-speed milling of the hardening steel and parts.This essay focuses on the optimization of technological parameters of machining hardened steel. The origin of this study is the vital special scientific and technical subject of Guangdong province "the key processing technology research on the ultra precise machining of the mold of casting plastic".The main contents of this essay are as follows:1. The relation between the technological parameter (include cutting speed and per tooth feed ) and the cutting force, the relation between the tool extend length and the cutting force are studied when using flat endmill and ball endmill to machine hardened steel respectively.2. The influences of cutting parameters such as tool extend length, cutting speed, feed rate, axial cutting depth and radical cutting depth on the cutting rate and cutting force are studied basing on orthotropic experiment to obtain a group better-suited technology parameters.3 The optimal technology parameters is applied to make a core of mobile cover, which material is hardened steel, with sintered-carbide tool coasted by TiA1N made in China. The efficiency of process is increased and the qualification meets the requirement(Ra＜0.5μm). This specific group of cutting parameters can be applied in the related enterprise.The results show that:1. The maximum effect actor on the cutting force is the axial depth and the following are radical depth and per feed rate while the cutting speeds has the least effect on the cutting force when using flat endmill tools to cut hardened steel. In addition, the different cutting tool extend length has a certain fluency on the cutting force.2. The axial depth and the radical depth have the maximum effect on the cutting force when using the ball endmill tools to cut hardened steel. The cutting force is also in direct proportion to the axial depth and the radical depth. The second is cutting speed and the following is per feed rate. Then the cutting tool extend length has the least fluency on the cutting force. When the three parameters are increased, the cutting force may be bellow in some point.3. The optimal parameters for cutting force are not accordant with the optimal parameters for cutting rate. When focus on cutting rate, the greatest parameters should be selected but when focus on cutting force the most suitable parameters should be selected not the greatest one. To avoid the fast attrition of cutting tool and guarantee the machining quality we should select the parameters according to the requirement of cutting force.
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