Dynamic Analysis And Optimal Design Of Hydrostatic Worktable System

Hydrostatic worktable system is one of the key components of the CNC machinetool. The dynamic properties of hydrostatic worktable system have a great influenceon processing quality and efficiency of CNC machining equipment. Further dynamicmechanical study and optimal design on hydrostatic worktable system is of greattheoretical significance and application value to increase the carrying capacity andperformance, satisfy the demand for high-precision machining, and promoteindependent innovation and development of advanced manufacturing.The following aspects of hydrostatic worktable system are studied in this paper.(1) On the basis of Navier-Stokers equation in hydrostatic worktable oil film, thedynamic bearing capacity formulas of rectangular, sector and circular recess havebeen deduced. The integrated bearing capacity formulas have been obtained byintegrating dynamic and static bearing capacity. Then oil film stiffness formulas aregotten.(2) The finite element model of hydrostatic worktable system has beenestablished. Then modal analyses for different oil film models have been conductedand harmonic response analyses under different actuation force frequency have beendone. How different parameters of recess influences the natural frequency in modalanalysis, such as different recess depth, recess radius, width of oil film edge andinitial oil film thickness, have been analyzed. In addition different parametricalinfluences on harmonic response analysis, such as different recess number, elasticmodulus, oil film stiffness and damping coefficient, have been researched.(3) The optimal model is established, in which optimal objective is to maximizethe integrated bearing capacity and maximize oil film stiffness. Design variables areoil recess outer and inner radius, oil seal film thickness and recess depth andconstraint is the first order natural frequency. Multi-objective functions could betransformed into single objective function by hierarchical strategy. Constraint functionis fitting explicitly by response surface methodology. Feasible direction method isapplied to solve the optimal model. The program is stable and effective. Theconditions for improving the mechanical system’s properties are obtained.(4) The optimal model is established, in which optimal objective is to minimize dynamic displacements at key nodes. Design variables are recess number, radius andheight of table and constraint is the low-order frequency. Objective function is fittingexplicitly by polynomial regress methodology and constraint function is fittingexplicitly by response surface methodology. Quadratic programming is applied tosolve the optimal model to obtain the high precision when hydrostatic worktable is onwork.This project reaches the standard of expectation to help designers understand thedynamic performance of hydrostatic worktable system. The procedure of optimaldesigns provide theoretical basis in practical new generation design of product.