| Cutting is one of the traditional and basic techniques in mechanical manufacturing industry. Since the 1980s, cutting technology has developed into a new stage of high-speed cutting, and makes high-speed cutting gradually become the mainstream cutting. The cutting system consists of three parts, and they are machine tool, interface system and cutting tool. Interface system, serving as a connection between spindle and cutting tool, is of critical significance for the whole cutting system.In the paper, the theoretical background and developing trend of high-speed cutting are introduced. It also demonstrates the core technology in high-speed cutting, as well the research status of interface system. The paper introduces a toolframe with an HSK interface system used in actual production and describes the detail of the problem with the toolframe.By using the basic theory and knowledge of elasticity and plasticity mechanics, the stress formula of high-speed rotation solid round spindle has been got, and the stress of the high-speed rotation toolframe is calculated according to the formula. The paper analyzes the fatigue fracture of the toolframe with cracks, and finds the ultra stress concentration that affects the fatigue strength of the toolframe and shortens its life. With the help of scanning electronic microscope, it is found that the ultra stress concentration is caused by the sudden change of the geometry figure of the toolframe.The structure improvement program is proposed to moderate the ultra stress concentration by setting a model with the three-dimensional drawing software according to the accurate size got from CMM, and using ANSYS to do finite element analysis. Through mechanics analysis of the toolframe, the author observes the situation of the stress concentration and designs a flow to choose the appropriate size to improve the structure of the toolframe. The improvement of structure achieves good results and receives recognition from the toolframe user.
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