An Investigation of the Performance of a Quick-Stop Device for Metal Cutting Studies

Summary

The specimen obtained by a tool quick-stop device should not be grossly influenced by the stopping conditions. Some previous investigators have reported measurements of extremely high deceleration rates for explosive quick-stop devices. However, these measurements are open to doubt since nearly all assume a uniform acceleration for the first few thousandths of an inch of tool displacement, and also, it can be shown that the reported accelerations would require explosive ‘shot start’ pressures and energies higher than seems possible.

The instantaneous chamber pressure and the displacement—time behaviour of an explosive quick-stop device have been investigated using a piezoelectric pressure transducer and a photo-optic comparator. The initial acceleration is shown to be highly non-uniform, with acceleration rates of around 10⁵ and 10⁶ in/s² in the first few thousandths of an inch of displacement (the stage of tool disengagement). The influence of variation in explosive charge weight, chamber volume and shearpin size is reported.