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MONOGRAPH 20

Scuffing of gears

Jerzy Tomaszewski i Józef Drewniak

Mechanism of scuffing gears and review of hypotheses elucidated reasons of occurrence of this phenomenon are described in this monograph. Review of theoretical methods of scuffing calculation of gears based on hypotheses of temperature contact of mating gears is presented in succeeding chapters. Methods of scuffing calculation based on PV, PVT, integral temperature, intensity of friction power FPI, Mansion and Blok scuffing criterions are described. Sizes influenced on scuffing of gears such as parameter of contact line and material, geometrical, angular coefficienta are presented also. Particular attension is payed to description of integral and flash temperature methods of scuffing calculation according to ISO standard 6536. Effect of selected design features such as teeth number of pinion, coefficient of tooth form shifting and oil viscosity on scuffing of gears are examined also. Much attention is devoted to describing practical methods of scuffing resistance test. In this part of monograph an example of calculation of scuffing permissible temperature according to ISO 6536 both for integral and flash temperature is presented. I order to calculate resistance of gears using flash temperature method, mathematical model describing energy transport in contact zone. This model enables to do calculation of temperature distribution on the tooth surface of mating gears. Suitable example of calculation of temperature distribution for straight gears is presented also. For qualifying scuffing resistance of industry gears average contact temperature method is used. Results of calculation this temperature compared with results obtained by using ISO standard 6536 is given. Average temperature method additionally enables calculation of values of dynamic friction coefficient, average conductivity coefficient and efficiency.
Last chapters are devoted vibrational diagnostic of gears scuffing. In this part of monograph vibration symptoms based on spectrum and vibration signals envelope analysis are presented.
Other practical methods of scuffing detection of gears and preventing this process are described. In the end results of measurements of influence of refined oil addition (Ceramizer) on kinematical parameters and friction coefficient improvement are also described.