| An extensive review of the literature indicated that studies on gear distortions were mainly metallurgically oriented, and the relationships between gear geometrical features and dimensional distortions due to heat treatment had not been investigated. This investigation obtained data from actual gear size adjustments that had been collected from many years of experimentations at the John Deere Component Works (JDCW), Waterloo, Iowa. Gear data were converted to uniform files and were classified, retrieved, and analyzed by computerized systems. Two groups of gears (helical and spur) were selected and analyzed.;Dimensional distortions due to heat treatment were the differences in measurement taken before and after heat treatment. These measurements were taken from the following dimensions: (1) Tooth thickness. (2) Lead. (3) Profile. (4) Crown. (5) Outside diameter. (6) Bore. (7) Internal spline tooth thickness.;Eleven research questions for helical gears and 10 research questions for spur gears were addressed. Answers to these research questions were presented in graphic form with statistical findings. The multiple regression statistical method was used to determine the correlation coefficient for each gear feature and each dimensional distortion. In addition, step-wise multiple regression was used to determine the relationship of a single dimensional distortion and a set of gear features.;For helical gears made of standard steel with a grade number of 1524 that had been carburized and quenched in hot or cold oil significant (p < .05) correlation coefficients were found between: (a) gear working pressure angle, module, tooth width, outside diameter, bore, approximate body/tooth volume ratio, and tooth thickness distortion, and (b) approximate body/tooth volume ratio and internal spline tooth thickness distortion.;The selected features included: (1) Working pressure angle. (2) Helix angle (helical gears). (3) Module. (4) Tooth width. (5) Outside diameter. (6) Bore. (7) Internal spline number of teeth. (8) Internal spline pressure angle. (9) Internal spline module. (10) Approximate body/tooth volume ratio.;Significant (p < .05) correlation coefficients were also found for spur gears composed of standard steel with a grade number of 1518 that had been carburized, slow cooled, received induction heating of the teeth, and quenched in cold oil. These significant correlation coefficients were between: (a) gear outside diameter, approximate body/tooth volume ratio, and tooth thickness distortion, and (b) cutter pressure angle and profile distortion. |
