Mathematical and computer simulation for the appearance of dimple defect by cold combined extrusion

The article is considered a comparative analysis for predicting defect such as dimple by energy method of power balance, upper bound and finite element method. takes into account the geometrical position dimension dimple, criterion formation in balance presence minimum point function relative pressure on velocity metal outflow vertical direction. New engineering calculations are developed combined radialbackward extrusion process using kinematic module with fillet. A obtained data has been carried out method, computer simulation Qform 2/3D program experimental data. Rationality view its efficiency possibility taking various friction conditions fillet matrix, well smaller deviations from results have defined. Providing more that favorable bottom billet flange area comparison glass wall contribute to delay appearance. It was found radius makes it possible appearance approximately (0,4 ÷ 0.5R) mm entered R. This allows us expand possibilities obtaining parts radial-backward without dimple.