An Experimental Impact-Extrusion Machine Driven by a Linear Induction Motor

Abstract

The linear induction motor as a planar development of the conventional rotary machine is described and the fundamental differences between it and the conventional machine are discussed.The effects of the discontinuities which occur in the linear machine, either in the stator as ‘short-stator’ effects or in the ‘translator’ as ‘short-translator’ effects, are discussed. The secondary member of the linear machine is referred to as a ‘translator’ in order to distinguish it from the rotor of the conventional rotary counterpart. The exploitation of the double-sided stator system is also briefly discussed.A linear induction motor has been constructed as an accelerator specifically for axi-symmetric impact extrusion. Some elements of design employed in the construction, together with a description of the model impact-extrusion machine, are given. The linear induction motor consists of a twin arrangement of double-sided stator systems, side by side, and in the same plane. The kinetic energy possessed by a mass accelerated in guides between the two stator systems is used for impact extrusion and the mass is propelled by the force exerted on a single-plate ‘dual translator’. The linear induction motor functions as a ‘short-translator’ machine.Experimental results presented show the nature of the accelerated motion of the mass, the force-slip characteristic, and how the overall energy efficiency of the linear induction motor is related to the root mean square phase voltage.Impact forward extrusions were performed for which \ in and 1 in diameter billets of pure lead and 1/2 in diameter billets of tellurium lead and super-pure aluminium were used. Some evidence is presented to show the limitations of impact extrusion.