Measurement of Die Deformation in Cold Forging by the Combination of Laser Displacement Sensor and Strain Gauge Method

The combination of laser displacement sensor and strain gauge method is newly devised to measure the elastic deformation of the tool-workpiece interface in cold forging. A deep hole is bored close to the inside surface of the die container. A steel pin is placed in the hole to detect the minute displacement near the die-workpiece interface. The movement of the pin is measured by laser displacement sensor. The displacement of the installation position of the laser sensor is measured simultaneously by the strain gauge method to adjust the measurement obtained from the laser sensor. This method is applied to the measurement of die deformation in the backward extrusion process. The displacement distribution over the die-workpiece interface under various conditions is obtained. It is proved that the newly developed method is effective for the measurement of die deformation in forging.