Research On The Calibration Technique Of3-TPS Hybrid Machine Tool

The hybrid machine tools(HMT)is a novel class of manufacturing equipment, which rises in recent years. By using HMT, it is easy to satisfy the requirements of multi-axis NC machining, assemble and measurement, so the HMT can be utilized to fabricate the parts with complex surface. Because of the advantages, such as its high ratio of stiffness to mass, fast response, module design and environment adaptability, it has been an important development direction of new generation machine tool. Many people in the worldwide range have resorted to develop the HMT and they have obtained some achievements. Some types have been applied in production. In our country, although domestic scholars and designers have gotten some research fruits, there is still a great gap compared to the level of the developed countries. One of the factors which limit the development of3-TPS hybrid machine tool is the accuracy of the HMT. It is still lower than the traditional precision NC machine tool. providing a detailed analysis of the machine tool errors and improving the accuracy of the HMT will accelerate the HMT to production.The basic principle of the HTM calibration technique is use the measured of kinematic parameters construct the error function, minimize the error function to the objective function and then identify the parameters of kinematics。Kinematic calibration of HTM can be divided into four steps:system modeling, error measurement, parameter identification and error compensation.The automation research institute of Northeastern University developed new3-TPS HTM.analysis of the structural sources error of3-TPS HTM,based on the inverse kinematics model of machine tool-buliding to describe the moving attitude and construct platform position,the last Calibration Experiment of the main structural error. The details are as below:With the whole machine for research object, define all the hinges of static and dynamic platform, derived inverse resolution equation and based on parallelogram mechanism deduced the forward and inverse kinematics. Analysis of hybrid mechanism and received machine institutional error,calibration experiment of the error of the HMT structure,to get each pole hinge point error and rod length error,these coorinate values instead of the theoretical coordinate values in the system.Carry on verification experiment on calibration of the HMT,analysis of calibration before and after the machine tool motion accuracy improvement. and analysis impact on experimental when introduction the measurement error.In this thesis,carry on calibration experimental on the rod length and hinge point of error of3-TPS HMT,It is playing a very important role in improving the accuracy.