Dynamical Analysis on the Hydraulic Control of the George Fischer KDM-18 Copying Lathe

Abstract

GF-KDM-18 hydraulic copying control mechanism has many points distinct from the old type which has already been published by the firm. A dynamical equation of the KDM-18 control system is given and the following items are analyzed theoretically : (1) Static characteristic of constant-pressure valve.(2) Frequency response concerning the displacement of tracer and that of copying slide.(3) Frequency response concerning the hydraulic pressure in annular chamber and that of control valve side chamber. As a result, KDM-18 control system can be assumed as the second degree control system. The theoretical results are supported by the experimental results with fairly good coincidence between them. Applying this theoretical analysis, the inter-relation between the displacement frequency response and the pressure frequency response is clarified. This implies the freedom of choice of experimental methods. Secondly, the estimation of the finishing accuracy of the copying control is discussed from the view of the frequency response. Finally, the practical recommendation that every control of the characteristics of the copying system can be done by the adjustment of the constant-pressure valve spring is presented.