At National Institute of Metrology, China (NIM), a portable and real-time self-calibration angle encoder was developed to meet the requirement of angular measurement with high accuracy, high speed, and high adaptability in limited size. In the development, the special arrangement of reading heads, the structure of bearing was designed base on the novel selfcalibration method, and the corresponding signal acquisition and processing system was set up with capability of high speed and multi-channel synchronous data acquisition and processing. The max rotary speed of this angle encoder gets 18 r/min (110°/s) in real-time mode. This angle encoder was compared with NIM’s primary angle standard. The calibration result shows that this angle encoder has angle measuring accuracy better than ±4″.
For correction of Abbe error in involute gear measurement, a laser interferometric measuring system is applied, in this system, the laser beam is split into two paths, one path is arranged tangent to the base circle of gear for measurement of profile, another path is arranged parallel to the gear axis for measurement of helix, two cube-corner reflectors are attached at the end of probe stylus closing to the tip, by this approach, the length offset between probe tip and reference scale is minimized , finally, the Abbe error is decreased. On another hand, the laser measuring error is caused by bending of stylus, the mathematic relationship between amount of bending and probe deflection is deduced. To determine the parameters in this mathematic relationship, two sizes of stylus are used for experiments. Experiments are carried out in a range of ±0.8mm for probe deflection. Results show that the amount of stylus bending is linear with deflection of probe, the laser measuring error caused by stylus bending will be smaller than 0.3μm after correction.
Gear measuring machine is a specialized device for gear profile, helix or pitch measurement. The classic method for gear measurement and the conventional gear measuring machine are introduced. In this gear measuring machine, the Abbe errors arisen from the angle error of guideways hold a great weight in affection of profile measurement error. For minimize of the Abbe error, a laser measuring system is applied to develop a high accurate gear measuring machine. In this laser measuring system, two cube-corner reflectors are placed close to the tip of probe, a laser beam from laser head is splited along two paths, one is arranged tangent to the base circle of gear for the measurement of profile and pitch, another is arranged parallel to the gear axis for the measurement of helix, both laser measurement performed with a resolution of 0.3nm. This approach not only improves the accuracy of length measurement but minimize the Abbe offset directly. The configuration of this improved measuring machine is illustrated in detail. The measurements are performed automatically, and all the measurement signals from guide rails, rotary table, probe and laser measuring system are obtained synchronously. Software collects all the data for further calculation and evaluation. The first measurements for a gear involute artifact and a helix artifact are carried out, the results are shown and analyzed as well.