Development of a Design System for Multi-Stage Gear Drives(2nd Report: Development of a Generalized New Design Algorithm)

Abstract

The design of multi-stage gear drives is a time-consuming process, since it includes more complicated problems, which are not considered in the design of single-stage gear drives. The designer has to determine the number of reduction stages and the gear ratios of each reduction stage. In addition, the design problems include not only the dimensional design but also the configuration design of gear drive elements. There is no definite rule and principle for these types of design problems. Thus the design practices largely depend on the sense and the experiences of the designer, and consequently result in undesirable design solution. We propose a new and generalized design algorithm to support the designer at the preliminary design phase of multistage gear drives. The proposed design algorithm automates the design process by integrating the dimensional design and the configuration design process. The algorithm consists of four steps. In the first step, a designer determines the number of reduction stages. In the second step,gear ratios are chosen by using the random search method. In the third step, the values of basic design parameters are chosen by using the generate and test method. Then,the values of other dimensions, such as pitch diameter, outer diameter, and face width, are calculated for the configuration design in the final step. The strength and durability of a gear is guaranteed by the bending strength and the pitting resistance rating practices by using the AGMA rating formulas. In the final step, the configuration design is carried out by using the simulated annealing algorithm. The positions of gears and shafts are determined to minimize the geometrical volume (size) of a gearbox, while satisfying spatial constraints between them. These steps are carried out iteratively until a desirable solution is acquired. The proposed design algorithm has been applied to the preliminary design of four-stage gear drives in order to validate the availability. The design solutions have shown considerably good results in both aspects of the dimensional and the configuration design.