Multicriteria design of a rotary table with a hybrid constant flow and constant pressure supply system

The rotary table of the heavy machine tools demands higher stiffness to provide substantial load capacity as well as a lower cost. The hydrostatic rotary table supplied with constant flow rate pump is not often used due to its high cost; meanwhile, the system with constant pressure pump suffers from a relatively lower stiffness problem. In this study, an alternative type of rotary table supplied by a constant flow pump and a constant pressure one is proposed to satisfy the requirements. The mathematical model is presented on the basis of hydrostatic theory to predict the axial static performance of the table. A comparison of the performances between constant pressure supply table, constant flow supply table and constant flow and constant pressure supply table has been conducted; the results show that constant flow and constant pressure supply table is the best in static behavior. A multicriteria optimization technique based on the weighted ideal point method is better than the single criteria optimization in achieving the comprehensive property of the table. A variation rate method is used to calculate the weighted factors. The optimization problem is formulated with the maximum stiffness, the minimum power dissipation and the minimum supply pressure.