Research On Failure Mechanism And Working Reliability Of HSK Tool System

High speed cutting technology has brought machining high production efficiency, high precision, high surface quality and many other advantages. It has become one of the major trends in manufacturing industry. With the development of machine drive technology and the tool materials, rotation speed of the machine tools is becoming higher and higher, it poses significant challenges for the tool system. The tool system used in high speed cutting must have good work reliability and security to ensure machining quality and safety. Once the tool system happens to fail, it would greatly destroy machining accuracy and surface quality. It may also cause significant harm to the machines and the operators. Therefore, it is greatly significant to research high speed cutting tool system. In recent years, HSK tool holders have been widely applied in high speed cutting machine tools, It is considered one of the most suitable tool-holder forms for high speed cutting machine. And the HSK tool system even be considered as "a tool system for the21st century ". This paper summarized the three main failure modes of the HSK tool system. The HSK-A63type tool system was used as research object. In viewing of the main failure modes, failure mechanism and working reliability of the HSK tool system were analyzed. Main contents are as follows:(1) By considering the strength failure, an equivalent stress model of HSK tool system under the condition of high speed rotation was established. And it was verified by using of finite element method. According to the stress model, a reliability model of the HSK tool system based on its strength was established by using of the stress-strength interference theory and Monte Carlo method. Finally, a calculation example of reliability was carried out.(2) By considering the connection failure between HSK tool-holder and spindle, the deformation of the HSK tool-holder and spindle at high rotational speed was analyzed. And a contact stress model on the HSK tool-holder and spindle contact surface was established. According to the contact stress model, the critical rotational speed based on connection was discussed. The contact stress model was verified by using of finite element method. And the influence of the interference, initial clamping force and rotational speed on connection performance was also analyzed. Finally, a reliability model based on connection between tool-holder and spindle was established. Meanwhile, a calculation example of reliability was given.(3) By considering the vibration failure of the HSK tool system, the causes of imbalance and vibration mechanism caused by imbalance were analyzed. The vibration response induced by unbalanced exciting force was obtained by using of finite element method simulation. Spin and dynamic stiffness experiments were designed and carried out to analyze the influence of unbalance on vibration and to evaluate the ant-vibration ability of the HSK tool system.