OBRABOTKAMETALLOV Vol. 23 No. 3 2021 MATERIAL SCIENCE EQUIPMENT. INSTRUMENTS 6 2 4 Since in the process of molding the inner spherical surface of the outer ring as a result of bilateral sintered blank upsetting, the relative displacement of metal on the surface of the inner ring is insignificant, in the process of experimental studies did not observe adhesion or splicing of the material of the outer and inner rings of the bearing. When die forging porous blanks, it is necessary to identify the distribution of material density in each stage. The top and bottom edges of the outer bearing are most intensively compacted when the punch faces are produced with a chamfer angle of 30–40 deg. With increasing εz up to 0.30–0.35, residual porosity in these zones (have dark orange and red background) does not exceed 0.5–2.0 % (Fig. 5, a). εz Relative density Strain resistance, MPa Accumulated deformation field 0.093 0.174 0.244 0.306 0.345 Fig. 5. Volume distribution of relative density (a), specific strain resistance (b) and accumulated deformation field (c) during simulation of die forging of a porous blank in QForm program To experimentally evaluate the distribution of residual porosity in the bearing outer ring after cold forming, microsections were used. (Figs. 6, a and 6, b) show the microstructure of the unetchedmicrosections of two areas of the meridian section of the ring with maximum (Fig. 5, a, has a red background) and minimum (Fig. 5, a, has a bluish background) relative density. Porosity in these zones does not exceed 1–2 and 7–9 %, respectively. These studies show a fairly good agreement between the results of simulation and experiment in estimating the density of the material. In the cold forming process, the relative density θ increases in proportion to the accumulated strain (Fig. 5, c). For example, θ of the material in the region of the inner spherical surface of the ring, depending on the height and degree of strain (εz = 0.33–0.35) ranges from 0.92–0.98. Since the central inner part of the blank is compacted to a lesser extent than the ends, on the one hand, it allows to increase the amount a b c
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