Research On The Friction Testing Method And Device In Bulk Metal Forming

Bulk metal forming is a very important process of metal brick, bar and thick board athigh temperature or room temperature in the plastic forming, and widely used, includingforging, extrusion, rolling, drawing, spinning, rotary forging, etc. Over the years, muchwork has been devoted to the study of bulk metal forming from three aspects ofexperimental simulation, theoretical analysis and numerical calculation. Friction is one ofthe important behavior of metal forming. Its presence greatly affect analysis of force andenergy, surface quality of the product and die life of the bulk metal forming. Therefore,study of friction in bulk metal forming process has important significance.The paper regards typical open-die extrusion as research object and studies frictioncondition in bulk metal forming. Through the analysis of open-die extrusion process byupper bound method, the analytical formula between unit extruding force in stableextrusion stage and friction factor is obtained. Through the analysis of the criticalcondition for open-die extrusion, the feasible extrusion angles of die are selected and thefriction factor testing method is established.The process of the open-die extrusion is numerical simulated by the finite elementsoftware called Deform with simplified coupled thermal-mechanical FEM model underdifferent temperatures, friction factors and extrusion speeds.This paper sets up friction factor testing analysis system and makes relatedexperimental study. The system has some relative stability and can provide data forfriction coefficient testing and study. The results of experiments show that lubricationeffect of boron oxide adding an quantitative graphite is better and the impact oftemperature on the friction factor is not a linear trend.