PUNCH FOR BROACHING AT PRESS Russian patent published in 2015 - IPC B21J5/10 B21J13/02 

FIELD: machine building.

SUBSTANCE: punch for broaching is made as a body of rotation with two holes. The outer diameter of the punch is alternating. The said diameter at the punch length section from its front end face being equal to the inner diameter of the produced hollow billet is equal to the said inner diameter of the hollow billet. Along the remaining length section, the punch diameter is constant and is by 2 mm less than the inner diameter of the hollow billet. One of the holes is through, has the diameter alternating by the length and the axis matching the punch axis. The diameter of the said hole at the length section from the punch front end face equal to its maximal outer diameter is equal to 2/3 of the said punch diameter. Along the remaining length section, the hole diameter is constant and is by 2 mm greater than the hole diameter at its length from the punch front end face. The second hole is fitted by an axis crossing the punch axis at the right angle. The axis of the second hole is set at the distance from the punch front end face equal to 4/5 of the punch length. The diameter of the second hole is constant along the whole hole length and is equal to 5 mm.

EFFECT: improved quality of broached billets due to the reduction of their wall thickness variation and elimination of faults, reduction of friction at the outer and inner surface of the punch.

6 dwg, 1 ex