“Metrology of gears checks smoothness of operation, freedom from vibration and noise ……”
P R Trivedi, GM Manufacturing, Mahindra Engineering and Chemical Products Ltd.,MIDC Pimpari
MEASURING GEARS
Gears are essential elements in the drive systems of most machines and equipment. They are used in road, rail and air transport, and in a wide variety of industrial drives ranging from food processing, packaging and printing to quarrying, power generation, machine tools, robotics and steel making. In the past twenty-five years, there has been substantial development in gearing, resulting in a threefold torque density increase (relative to size and weight) and a reduction in real cost of 27%. This has been achieved by improvements in gear accuracy supported by improved gear metrology (e.g., probesystem measuring) and calibration accuracy. Lower uncertainty of calibration data has encouraged manufacturers to use the best metrology practices to reduce their measurement uncertainty and to improve gear accuracy.
The improved manufacturing capability of gear production equipment demands high-accuracy measurement equipment. The demand for quiet gears in all transmissions has increased due to changes in legislation and customer demand. Conventional gear measurement techniques are not able to identify the error sources, which are the cause of many noise and vibration problems. Existing gear metrology facilities in the world have the capability to measure gears up to 2.6 m in diameter and weighing up to 15 tonns. In practice, gear tooth vernier, base tangent comparator, involute profile-measuring machine, profile projector, etc., are in use; but on the other hand, many considerably larger gears are produced but their tooth profiles cannot be measured. A portable tooth-profile-measurement instrument is still one of the requirements of the industry for checking gears during production and assessing wear or damage of gears during service.