Abstract: The paper presents experimental results of one-sided and two-sided bulge forming of reducing tubes with different angles of flare alpha=30 degrees, 45 degrees and 60 degrees The Investigations into bulge forming involved the use of R35 steel tubes at the relative ratios s(0)/D=0.05, 0.07, 0 10 The comparison of experimental and theoretical forces in one-sided bulge forming showed no significant differences In one-sided bulge forming investigations, changes in the wall thickness in the longitudinal sections of bulged reducing tubes at the punch displacement of Delta l=20mm, together with the corresponding force profiles, were compared In the last stage of investigations the comparison of experimental results of two-sided and one-sided bulge forming at s(0)/D=0.07 and different angles of flare alpha, alpha(1), alpha(2) for values 30 degrees, 45 degrees, 60 degrees (where alpha- the angle of flare of one-sided bulged reducing tube, alpha(1), alpha(2) -angles of flare of two-sided bulged reducing tubes) was made It was shown that two-sided bulge forming is possible both at the same angles of flare (alpha(1)=alpha(2)=30 degrees, alpha(1)=alpha(2)=45 degrees, alpha(1)=alpha(2)=60 degrees) and different angles (alpha(1)=60 degrees and alpha(2)=30 degrees; alpha(1)=60 degrees and alpha 2=45 degrees, alpha(1)=45 degrees and alpha(2)=30 degrees), which was demonstrated by successful tests carried out at the upsetting ratio Delta l/l(0)=0.75.
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