Macro and micro geometry optimization of four-speed gearbox

While providing the basic strength requirements in gearbox design is the main goal, efficiency, silence, and lightness are other important features to be considered in terms of applicability and competition. In conjugate gear wheels, choosing suitable geometric variables according to the application area is of great importance in terms of operating parameters and strength. In this study, macro and micro geometry optimization was performed using KISSsoft commercial software on the four-stage reference gearbox used in the drilling machines. In the first part of the study, macro-geometry optimization was made by considering the "ISO 6336" standard for the selection of the appropriate geometric parameters for the gear pairs that can safely transfer the motion and power from the hydro motor used as a power source to the output shaft. In the second part, micro-geometry optimization was made for the appropriate profile modification in order to create conjugate motion under dynamic conditions, improve the contact state and provide a more efficient and silent operation. The strength values and working parameters of the gear pairs created as a result of macro and micro geometric optimization were compared with the values before optimization. The effects of macro and micro geometric optimization on gear design were demonstrated by calculating tooth root and surface strength separately according to ISO and DIN standards As a result of the study, gear sets that provide sufficient tooth root and surface strength, with improved efficiency, noise level, and reduced mass, were formed in the gear system.