Theoretical and Experimental Analysis of Stick-Slip in Hydraulic Driving Mechanisms

The discontinuous motion of a body sliding at low velocity is known as stick-slip. In this paper, stick-slip in hydraulic driving mechanisms is analyzed quantitatively on the bases of the characteristic of flow control valve, the equation of continuity for oil flow and the equation of motion for the sliding element under the assumptions that the characteristic of flow control valve is linear and the friction between sliding surfaces is composed of static, Coulomb and viscous friction. An experimental verification of the theoretical analysis is made using the model table which is the same size as a table of No. 2 1/2 milling machine. Then it is shown that the motion of a table in stick-slip can be described by the pressure-flow characteristic of flow control valve, the friction-velocity relation between sliding surfaces, the compressibility of working oil and others.