High-speed Cutting Tool Connected System Stress And Deformation Analysis

The high-speed cutting (HSC) is now recognized as one of the key manufacturing technologies for high productivity and throughput. The main components of machining system are the machine tool, the toolholder/spindle interface and the cutting tool. Machine tools with high rigidity and high power/high rpm spindles are available, as well as high performance cutting inserts. The weakest parts in the machining system is the toolholder/spindle interface system, whose stiffness is relatively low and thus negates the expensive efforts invested in stiffing the machine tool structure.Interface system must play two important roles simultaneously. One is precision location of the toolholder relative to the spindle. Another is clamping to provide adequate rigidity to the connection. When the spindle rotates at high speed, the spindle bore and the toolholder elastically expand due to the increase in centrifugal force, and the contact at the tapered face consequently become loosely. This will influence machining precision, lead to chatter vibration, worsen the machining surface quality, and shorten the tool life. This situation will be especially evident at high rotation speed. Therefore it's very important to improve the performance of tool interface system.Firstly, the technical system of HSC and its development trend have been reviewed. The advantages of HSC have been presented, as well as the application and recent development of cutting tools and machine tools for HSC, and their related technology especially in the last decade.The model of tool interface system has been built up based on equilibrium equation, elastic constitutive relationship, strain-displacement relationship and boundary conditions by using the theory of elasticity and plasticity. Then the deformation due to centrifugal force of the model has been analyzed and the limiting speed of the toolholder has been calculated.At last, the standard 7/24 toolholder/spindle interface, which is the most popular interface system, and HSK system (which is the most prominent new interface system developed during the last decade) have been selected to study. Using the finite element method and polynomial fitting, the deformation and contact pressure distribution of the selected interface at high rotation speed has been precisely simulated. And the influences on the performance in terms of axial and radial stiffness, and the positioning accuracy of the tooling system have been analyzed. The results indicate that HSK tool interface is more suitable than 7/24 tapered interface for high speed machining. Finally, influence of interference and axial preload on the performance of HSK tool interface has been surveyed.