Sensor-based measurement of tool forces and machining process model parameters

摘要

A system and method are provided for real-time measurement of tool forces. A relationship between a sensor characteristic and tool forces is determined by first directly measuring tool forces for a standard tool, work piece, and part program in a central facility. A force profile indicative of the tool forces and the standard tool, work piece, and part program are provided to a user at a user facility. The sensor characteristic for a CNC machine at the user facility is then measured for the standard tool, work piece, and part program. Based on the force profile determined at the central facility, the relationship between the sensor characteristic and tool forces is determined. Thereafter, the sensor characteristic of the CNC machine is measured for a work piece, part program and desired tool and converted to tool forces using the relationship between the sensor characteristic and tool forces. The resulting tool forces may be combined with a process model to obtain process model parameters or cutting energies for the work piece and the desired tool. In cases where the sensor is not conveniently attached to the work piece or when the part program is not sufficiently robust in cutting conditions to accurately determine the process model parameters, the work piece and part program are replaced by a sacrificial work piece and sacrificial part program. The sacrificial work piece and sacrificial part program are selected to both accommodate the sensors and to provide sufficient robustness in cutting conditions to accurately determine the process model parameters for the sacrificial work piece. The process model parameters for the desired work piece are obtained from the process model parameters by, first, obtaining the averaged tangential tool forces for the desired work piece and for the sacrificial work piece by measuring the spindle motor power and applying the relationship between spindle motor power and tangential tool forces for each work piece, second, obtaining a ratio of the averaged tangential tool forces for the desired work piece and the sacrificial work piece and, third, applying this ratio to the process model parameters for the sacrificial work piece to obtain predicted values for the tool forces and the process model parameters for the desired tool and desired work piece.