| CNC machine tools are important in manufacturing machine tools, whose dynamic characteristics will directly affect the machining accuracy and processing efficiency. With the rapid development of modern manufacturing industry, companies of CNC machine tools have become increasingly demanding in order to get a good machining performance. In order to obtain good yields, companies hope to obtain a higher productivity of the workpiece, therefore, they become to pay more attention to the machining efficiency. Machine tool during machining curved surface parts, because the surface of the curved contour of the more complex parts, the process is more complex than ordinary flat profile, machining worktable requires frequent moving back and forth to finish machining. Table in reciprocation process requires frequent start and stop, the dynamic performance of CNC machine tools made higher requirements. CNC machine tools with poor dynamic performance can not reach the more efficient processing in the processing. Therefore, in the study of the dynamic characteristics of machine tool feed system becomes very important.This paper takes the current CNC machine tools mare commonly used ball screw feed system on as the main object of study, and analyzes the structure and dynamic characteristics. Firstly, it analyses the reasons of slow motor response when surface machining. When the motor is selected, its own torque and moment of inertia is a constant value, machine tool feed system load torque is the main factor affecting the motor start and stop. The different structure of load rotational inertia proposed should comply with the conditions and formulas. Analysis of the composition and calculation of torque load of machine tool feed system.Through ball screw stiffness calculation, analysis of axial and torsional deformation due to the cutting force of machining process. With the screw is simplified, this paper calculate the horizontal and vertical directions torsional deformation caused by the cutting force. Friction changes caused by the deformation of the screw changes during movement was calculated. Finally, through force analysis of work table, this paper studies the change in resistance of the machining process when the rail appears straightness errors in the horizontal plane. Determine the relationship between the rail straightness errors and force change which has certain significance for the calculation of the load torque.Through the above analysis, this paper studies the dynamic characteristics of machine tool feed system, and describes the influence of dynamic characteristics of machine tool on machining efficiency. It is important to study on how to improve the machining efficiency of CNC machine tools. |
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