Machine tool for machining crankshafts and control system for the machine tool

A machine tool for machining crankshafts, comprising:

• (a) a frame having a fixed longitudinal axis;
• (b) workpiece holding means mounted in said frame for rotation about said axis and adapted to support and to be non-rotatably connected to a crankshaft centered on said axis;
• (c) a tool carriage slidably mounted on said frame for a displacement which is transverse to said axis;
• (d) first drive means for imparting an angular rotation to said workpiece holding means about said axis;
• (e) second drive means for displacing said tool carriage in said transverse direction;
• and
• (f) control means having first and second separate but identical controllers for independently controlling said first and second drive means respectively such that said angular rotation and transverse displacement are each performed in a predetermined nonlinear relationship in response to independent control signals applied via a pair of mutually non-interactive drive channels, each channel including one of said first and second controllers.

A control system for a machine tool for machining crankshafts, which machine tool comprises:

• a frame having a fixed longitudinal axis;
• workpiece holding means mounted in said frame for rotation about said axis and adapted to support and to be non-rotatably connected to a crankshaft centered on said axis;
• a tool carriage slidably mounted on said frame for a displacement in a direction which is transverse to said axis;
• first drive means for imparting an angular rotation to said workpiece holding means about said axis;
• second drive means for displacing said tool carriage in said transverse direction;
• said control system being adapted to control said first and second drive means so that said angular rotation and said transverse displacement are performed with a predetermined, generally nonlinear relationship to each other, and comprising:
• (a) a first controller operatively connected to said first drive means for imparting a desired angular rotation to said workpiece holding means;
• (b) a second controller operatively connected to said second drive means for imparting a desired transverse displacement to said tool carriage;
• (c) drive control computer means for processing workpiece and tool data and for computing from said data a plurality of points of inflection and characteristic values defining a series of linear approximations of said generally nonlinear relationship, and for generating approximation data representing said approximations;
• and
• (d) interpolating means operable to receive said approximation data and to apply independently controlled angular rotation and transverse displacement reference inputs to both said controllers in dependence on said approximation data and thus to control said angular rotation and said transverse displacement in accordance with said approximations.