| The high speed cutting tooling system is one of main parts of high grade CNC machine tool and the performance of tooling system will directely affect machining quality and production efficiency. HSK shrink toolholder and tooling system is one of high speed cutting tooling systems. As there are some advtantages of HSK shrink tooling system, which are short drive chain, high stiffness and reliable connection performance, the tooling system are widely used for high speed cutting. At last, studying the dynamic performance and cutting stability of HSK shrink tooling system can improve machining quality and production efficiency of High grade CNC machine tool.The paper studies HSK spindle-shrink toolholder-tool system dynamic performance and cutting stability with thereotical analysis, FEA and experimental method. Then, the parper aims to build HSK spindle-shrink toolholder-tool system dynamic model, reveal HSK spindle system dynamic performance. Also, the joint part parameters are identified accurately and the HSK spindle system tip-point FRFs are predicted with coupling receptance theory. Also, the displines which joint parts affect HSK shrink tooling system dynamic performance are studied. The HSK shrink tooling system milling dynamic model are bulilt, the stability lobes are calculated with chatter theory. At the same time, HSK shrink tooling system milling experiments are carried out, the cutting stability displine s are explored. The main reaserch works are: 1. The Dynamic Model of HSK Spindle-Shrink Toolholder-Tool System based on Joint Parts According to HSK spindle system structure, the model of HSK spindle-shrink toolholder-tool system based on joint part is built. Among them, the bearing-spindle joint part is simplified as spring-damp model, the HSK spindle-toolholder joint part and shrink toolholder-tool joint part are regarded as multiple spring-damp models with parallel uniform arrangement, and the HSK spindle, shrink toolholder and tool are treated as Timoshenko beam model. 2. Propose a New HSK Spindle System Tip-Point FRF Computing Method The multi-points coupling receptance method based on Timoshenko beam theory is proposed to compute HSK spindle-shrink toolholder-tool system tip-point FRF. HSK spindle tip-point FRF is computed with structural modification method and coupling receptance way. Also, the tip-point FRFs of HSK shrink toolholder and tool are gained with coupling receptance method. Moreover, the tip-point FRFs of HSK spindle-toolholder joint part and shrink toolholder-tool joint part are obtained with multi-points coupling receptance method. At last, the tip-point FRFs of parts are coupled rigidly and the tip-point FRF equation of HSK spindle system is derived.3. Propose a Mew Method to Identify HSK Spindle-Toolholder Joint Part Parameters and Shrink Toolholder-Tool Joint Part ParametersThe stiffness parameters by finite element analysis (FEA) and damp parameters by finite difference method (FDM) are used to be joint part parameters. Firstly, the stiffness and damp parameters (c·ω) in different locations of interface are identified and the elements affected joint part parameters are discussed. Secondly, the stiffness and damp parameters at the end of interface are identified with FDM and experiment. At last, making the HSK spindle-holder system and shrink toolholder-tool system beam model and considering the identification parameters, the system dynamic performance is studied. Compared the theoretical modal and experimental one, the accuracy of stiffness parameters and damp parameters is confirmed.4. HSK Spindle-Shrink Toolholder-Tool System Dynamic Performance and Factors DisplinesAccording to the parallel characteristic of stiffness, the stiffness parameters in different locations of joint parts can be equivalent to the end point of joint part, and the multi-points joint part can be simplified as only one spring-damp model. On the basis of HSK spindle-shrink toolholder-tool system dynamic model, the dynamic performance of HSK spindle system is analyzed with coupling receptance method. Comparing the HSK spindle system modals in different joint part stiffness parameters, the factors laws of joint parts affecting HSK spindle system dynamic performance are explored.5. HSK Spindle-Shrink Toolholder-Tool System Milling Dynamic ModelThe stiffness of part system is much higher than HSK shrink tooling system, so the stiffness of parts can be neglected. The HSK shrink tooling system dynamic modedl is built with orthogonal two freedom system. Based on chatter method, the calculation of stability lobe can be calculated. Conserning the tip-point FRF of HSK shrink tooling system, part material, cutting datum and tool angel, the stability lobe can be predicted.6 HSK Shrink Tooling System Milling Stability ExperimentKeeping the spindle rotation speed and radial cutting depth parameters the same, the milling force experiments are processed with different axial cutting depth parameters. What’more, HSK spindle-shrink toolholder-tool system cutting stability status is judged on the basis of time-domain cutting force signal and the accuracy of theoretical cutting stability lobes can be identified.So, identifying accurate the joint part parameters, studying the high speed cutting spindle system dynamic performance and exploring the factors laws of joint parts affecting HSK spindle system dynamic performance, this can provide theoretical foundation for developing new high speed cutting spindle system. In addition, Making HSK spindle system milling dynamic model, predicting tip-point FRF of HSK spindle system, computing and analyzing stability lobes, this can avoid chatter and provide theoretical guarantee for high speed cutting stability. Also, this can provide theoretical guidance for HSM spindle system optimization. |
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