Abstract:Gears are very old machine elements, but they still exist in modern industries. For example, in an automobile industry, gear performance plays and important role for comfortable driving, energy consumption, and so on. In electric equipments, miniature gears are used to transmit rotational motion in high accuracy without delay motion. In addition, the progress of micro electro mechanical systems brings us the new stage of nano-manufacturing. Micro gears have also been manufactured in this process nowadays. In all cases mentioned above, measurement of gear accuracy is also essential for evaluation of manufacturing errors, meshing status and running performance.
This paper describes some topics of gear manufacturing and measurement with respect to their accuracy evaluation and performance. (1) With respect to manufacturing, large size gears are conventionally manufactured by cutting, so called hobbing process. The cutting phenomenon in the complicated hobbing process was captured by high speed camera and transient situation of chip formation was evaluated. (2) Concerning to the gear individual accuracy, gears have originally concave parts as tooth spaces and they must be measured with the nondestructive method. Tooth root and bottom accuracy were measured by scanning method by specially developed CMM. (3) About transmitted accuracy, it was directly evaluated by rotational angle measurement with a pair of rotary encoders with nanometer resolution. (4) For micro gear systems, a contact type or an optical stylus could not reach deeply inside a tooth space because the adjacent tooth interferes with the stylus going. Micro stylus for micro gear measurement was manufactured by nano-manufacturing technique, and also a design and trial manufacturing of a grating disk with a small diameter for a micro rotary encoder for measurement of micro gear transmission accuracy.
Keywords: Gear metrology, High speed image recognition, CMM, Transmission error measurement, nano-manufacturing, micro rotary encoder