Theoritical and Experimental Analysis of Stick-Slip in Hydraulic Driving Mechanism

Abstract

Stick-slip is sometimes observed in the sliding surfaces of machine tool. In this paper the Characteristic of 4-way valve, the equation of continuity for oil flow and the equation of motion for the sliding element are described. Stick-slip is analysed quantitatively under the assumptions that the characteristic of 4-way valve is linear and the friction is composed of static friction, coulomb friction and viscous friction. An experimental veriflcation of the theoritical analyses is shown, using a model table which is same size of the table of no. 2 1/2 milling machine. It has become apparent that friction-velocity relation and oil compressibility are two major factors for the growth of stick-slip. It is shown that the motion of table in stick-slip can be described by 4-way valve pressure-flow characteristic, friction-velocity relation, oil compressibility and the sizes of the hydraulic driving elements.