Proposal of Tribosimulator for Forging by Taper Cup Test

Abstract

A lubricant plays an important role in forging; it can reduce forging load and allow smooth retrieval from the die. In the conventional tribosimulator, the ring-compression test and the spike-forging test have been used widely. However for forging conditions such as those in flange-bolt and CVJ(constant velocity joint) forging operations, is much severer in terms of the surface-expansion ratio and pressure than that of the conventional tribosimulator. Thus, the establishment of a new tribosimulator for severe forging conditions has been desired strongly. Therefore, a new tribosimulator with a high surface expansion condition under high normal stress, in which the optimum die shape is designed by fine element analysis, is proposed. A new tribosimulator is a type of backward-extrusion test using a taper punch, which is named the "taper cup test". In this test, the surface expansion ratio can be changed by controlling the penetration depth of the punch, and it is possible to obtain the forging limit of the lubricity by measuring the change in the forging load.