STRAINS OF DRAWING INITIATION OF CYLINDRICAL BILLET AT THE HOT FORGING IN COMBINED ANVIL BLOCKS

The model of hot drawing of steel cylindrical billets of small diameter in the combined anvil blocks for obtaining of forgings of a circular section was constructed. The authors considered the plane strain schema. The calculation of stressed state is the way to solve a problem of Michel for an elastic wedge, a problem of Flaman for a semi-infi nite plate and offered before method of an assessment of transferring in plastic condition of billet at drawing in fl at anvil blocks. The temperature stresses were not considered; the elastic modulus of the billet material depends on temperature. The fi elds of tensors of elastic stresses in the billet, three concentrated forces caused by action were defi ned; the fi eld of total stresses depending on angle of cut of the inferior anvil block was constructed. The assessment of stresses in a region of prospective plastic fl ow in the preparation section, leaning against limiting values of intensity of a tensor of the elastic stresses caused by action of three concentrated efforts was obtained. The example of drawing of the billet of steel 45 (Russian grade) was considered. Identifying limiting intensity of elastic deformations εуп with technical yield point ε0.2 = 0,002 and estimating elastic modulus Е of steel 45 100 hPa at temperature 950 °С, the authors have received values of coeffi cient of load at the moment of transferring of a part of billet material in plastic condition and distribution of component total tensor of stresses. The level of intensity of the stresses, corresponding to transferring of billet material into plastic condition, has defi ned the border of plastic layer. The conforming graphs were presented. Dependence of distribution of a component tensor of stresses from angle of cut of the inferior anvil block was received. The optimality of angles of cut of 120° of the inferior anvil block was confi rmed for drawing operations of the billet.

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