CONCEPTION OF UNIVERSAL EXTENSOMETRIC CUTTING DYNAMOMETER

This paper presents and describes the design, manufacturing, calibration and performance of a universal cutting dynamometer based on the principle of extensometer strain gage techniques. The device developed in this paper was designed and calibrated for measuring separately components forces developed during turning, drilling and milling operations. Its design is carried out according to the two principal criteria which are in contradictory matters such as sensitivity and rigidity. It consists principally of two circular rings, one allowing its fixation on the tables of the three type of machine tools, and the other one is machined so that the complete dynamometer can be attached to machines tables. The strain gages are then cemented on the parts of the dynamometer where the deformations (traction, compression and torsion) are maximum. The gages are connected in the form of a full wheatstone bridge, any unbalance in which would indicate the thrust force ant the torque providing maximum sensitivity and complete temperature compensation. The disposition and the connection of the strain gages in complete Wheastone bridge are carried out according to the force component to measure while taking account of the interactions between the three directions and the compensation of the effect of the temperature. The reading is indicated on standard indicator of constraints B & K 1526. Some experimental measurements of components forces and torque in the drilling process obtained with the described dynamometer are presented and compared with available data given by other research worker.