A SENSOR FOR MEASURING METAL DEFORMATION INTERFACE FORCES

Friction is always present at the workpiece-die interface in metal for ming. It is an important parameter which is often estimated, by necess ity, and has an important influence upon product surface quality and l ubrication. The development of a sensor to measure interface forces in metal-forming processes has been a research goal at Queen's Universit y Mechanical Engineering for a considerable time. A mechanical sensor, which uses strain gauges mounted on a conical cantilever sensing elem ent, has now been designed, successfully, to measure the three forces of interest at the roll/strip interface, namely: the normal force, the friction force in the rolling direction\and the frictional force in t he direction transverse to rolling. Successful tests have been conduct ed with the sensor using 1100 aluminium. When integrated through the r olling arc of contact, the forces measured at the roll/strip interface match the externally measured torques and roll separating force, ther eby showing that the sensor is measuring the interface forces accurate ly. The results of these tests are presented. The differences between the sensors that have been part of the research program leading up to the latest design are discussed in detail showing the reason for the p roblems which arose with each particular design up to the latest succe ssfully operating sensor. The experimental results presented are for b illet rolling. It can be seen from the results that when the transvers e friction force, which is orthogonal to the rolling direction, is add ed vectorially to the friction in the rolling direction, a friction ve ctor occurs which is not parallel to either axis of symmetry. Experime ntal results are presented for two reductions: 20 and 24.2%.