| Double milling cutters CNC screw machine that equipped with two milling cutters is a new type of screw processing equipment.The processing time of the screw length of 3.6 meter has been cut from 18 hours to 10 hours,which shorts the production period and greatly increases the efficiency.In the foundation of summary and analysis of the CNC screw machine structure design,for the problem of the improvement of machining accuracy,radial feed system is selected as the research object.The Kinematic analysis of the main drive gears of radial feed system was finished and the dynamics model of radial feed system was established.The simulation was carried out on radial feed system by using ADAMS.In order to verify the model,the actual machining text experiment and data analysis was done at last,which provided optimized basis for improvement of the machining precision.In this paper,the main research content include:First of all, summarizing the current situation of mechanism dynamics globally and aiming at the problem of machining tolerance of the screw in radial feed direction,the radial feed system was determined as the object of research and ADAMS was selected as a research platform through the analysis of the design scheme,the machining process and tolerance.Secondly, after the measurement of the size of radial feed system and knowing the hardware and technical parameters of the CNC screw machine radial feed system,Pro/E model was established and the stress analysis was finished on the actual working condition.Thirdly, the kinematics analysis of the gear drive and the screw transmission mechanism was accomplished, and error transfer function which cause by the component parameters error was established under the actual situation.What’s more,the radial feed system dynamics model was developed based on the theory of the Hertz,dynamic friction and Lagrange equation.By changing the size of installed tightening torque of the sliders, the system input torque and the dynamic characteristics of the system would be changed.At last,the better system dampingcharacteristics would been found out which can improve the system stability and machining accuracy.Fourthly, the radial feed system Pro/E model was imported into ADAMS and ADAMS was used to accomplish the dynamics and kinematics simulation. Dynamic and kinematics model curve of the radial system was calculated.Fifthly, the field test of the output angle of the gear drive, radial displacement of screw transmission mechanism and radial acceleration of the radial feed system was achieved.According to characteristics of system structure and testing parameters,the experimental program and steps was designed.The data of angle,displacements and acceleration were collected and saved by the way of the preparation of LabVIEW data acquisition procedure and connection among IPC, data acquisition card and sensors,which got the parameter curves under the actual processing condition.Finally,the data processing and analysis.The data of angle and displacement were the basis to analyze transmission accuracy of the gear drive and screw transmission mechanism through the comparison with theoretical value.The integration of acceleration data in frequency domain was completed by used MATLAB,which acquire the amplitude curve of the system. The stability of the system processing was judged by the change of the system displacement fluctuation.The experiments come to conclusion that the system displacement fluctuation is first decreased and then increased with the reduction of the size of installed tightening torque of the sliders,which is in accordance with the trend of the results of theoretical mode.The analysis of this research is an important reference value for the improvement of machining accuracy of the radial feed system and the double milling cutters CNC screw machine. |
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