| Rotary axis is a critical component of the five-axis CNC machine tool,its kinematic error affects the performance of the machine directly.It is vital to measure the six degree-of-freedom(DOF)geometric errors of rotary axis.Angular position error is the most critical factor which impair the machining precision.In this paper,the measuring method of angular position error of rotary axis based on laser collimation is thoroughly researched,the error model is established and 360 ° full range measurement is realized by using the high precision servo turntable.The measurement system is developed which contains a fixed unit and a motional unit.The fixing unit is composed of a laser source,a single-mode fiber,a collimator lens,a four-quadrant detector(QD)and some other optical elements.The moving unit comprises a rotary axis to be measured and a plane mirror that fixed on the high-precision servo turntable.The beam from the laser source is collimated in parallel to Y-axis,and then reflected by the plane mirror fixed on the servo rotation stage and converged onto QD through the convex lens.After building the world coordinate system and coordinate systems attached to each moving part,an error model is deduced in this paper.The change of space attitude of each moving part is described accurately by the 3×3 transformation matrices and the influences of various factors on the measurement results is analyzed in detail,including the installation errors of the plane mirror,the installation and motion errors of rotary axis and servo turntable.The corresponding measurement system is set up to carry on the experiment.The experimental result is compared with the values measured by an autocollimator,the standard instrument measuring angular position error which can be accurate to 0.1 ",the maximum measurement deviation is 0.3".The maximum deviation of the repeated measurement is 2.4".Experiments results show that the measurement method can achieve high measurement accuracy and large measurement range. |
PDF Full Text Request