Combination loading transducer

Abstract

The performance and condition of a tool, workpiece or machine tool is sensed during machining operations by securing a single or plural strain gages to the tool holder. To increase the sensitivity of the strain gages on stationary tool holders, the tool holders are contoured to provide locations of higher strain in which the strain gages are attached. A single or plural strain gages are positioned to sense the combined effect of different strains such as axial thrust and torque and are electrically connected to provide a single Wheatstone bridge output 'signature' which may be monitored to detect a defective operation. In rotating tools, the single 'signature' output greatly reduces the coupling equipment such as rotary transformers and also reduces the monitoring equipment. A unique arrangement of a single strain gage or alternatively a plurality of gages enables monitoring of both torque and thrust simultaneously. The output from the plurality of strain gages can be made additive to increase sensitivity and yet requires only a single bridge circuit. The design is flexible in that the gages may be arranged for optimization of the single bridge output for either torque or thrust.