Automatic process control in a gear processing machine

A method for monitoring a machining process in which tooth flanks of pre-toothed workpieces are machined with a finishing machine, the finishing machine having a tool spindle for driving a finishing tool to rotate about a tool axis and at least one workpiece spindle for driving a pre-toothed workpiece to rotation, the method comprising:

• detecting a plurality of measurement values, the measurement values being values of a power indicator which indicates a current power consumption of the tool spindle while the finishing tool is in machining engagement with a workpiece;
• applying a normalization operation to the measurement values or to values of a quantity derived from the measurement values to obtain normalized values, the normalization operation depending on one or more process parameters, the normalization operation causing the normalized values to have a reduced dependency on the process parameters, the process parameters being selected from geometric parameters of the finishing tool, geometric parameters of the workpiece and setting parameters of the finishing machine, the normalization operation being based on a model of process force or process power describing an expected dependence of the measurement values on the process parameters;
• calculating at least one characteristic parameter of the machining process from the normalized values, the at least one characteristic parameter correlating with a predefined machining error of the workpiece;
• performing an analysis of values of the at least one characteristic parameter for a plurality of workpieces to determine a process deviation;
• changing the machining process to reduce the process deviation.

A finishing machine for the machining of tooth flanks of pre- toothed workpieces, comprising:

• a tool spindle for driving a finishing tool about a tool axis to rotate;
• at least one workpiece spindle for driving a pre-toothed workpiece to rotate;
• a machine control device comprising a control computer and a plurality of axis modules for controlling a process of machining the workpiece with the finishing tool;
• and
• software which, when executed on one or more processors, causes the one or more processors to carry out a method comprising:
• detecting device for detecting a plurality of measurement values while the finishing tool is in machining engagement with a workpiece, the detected measurement values being values of a power indicator which indicates a current power consumption of the tool spindle;
• applying a normalization operation to at least part of the measurement values or to values of a quantity derived from the measurement values to obtain normalized values, the normalization operation depending on one or more process parameters, the normalization operation causing the normalized values to have a reduced dependency on the process parameters, the process parameters being selected from geometric parameters of the finishing tool, geometric parameters of the workpiece and setting parameters of the finishing machine, the normalization operation being based on a model of process force or process power describing an expected dependence of the measurement values on the process parameters;
• analyzing the normalized values in order to detect impermissible process deviations;
• and
• removing a workpiece for which an impermissible process deviation has been determined.