Motion Accurcy Measurement Device by Using Parallel Mechanism for Multi-axis Machining Centers

The main purpose of this study is to develop a measuring device by parallel kinematics for measuring a motion accuracy of multi-axis machining centers. The initially developed measuring device had three displacement sensors and it could measure only position of the spindle because it had only 3 DOF. Optical linear encoders were used for the displacement detecting sensors, while the steel balls and permanent magnets were used for the joints of parallel mechanism. With the 3 DOF device the motion accuracy of machine tools with three-axis was measured. Since the mechanism of the joint was smooth and the sensor resolution was small enough, the measured result showed that the measuring device had an enough performance for the machining centers in normal accuracy. Then the 6 DOF measuring device was developed. It had six displacement censors and it could measure both position and posture angle of the main spindle. In spite of the adoption of parallel kinematics, the forward kinematics calculation was possible due to the sophisticated arrangement of sensors, thus the hispeed data acquisition could be possible.