BROACH FOR BROACHING POLYHEDRAL OPENINGS Russian patent published in 2005 - IPC

FIELD: metal working, cutting tools for working polyhedral openings.

SUBSTANCE: in order to enhance accuracy of opening and to lower roughness of worked surface, calibrating portion of broach is made with profiled pattern for removing allowance. Along the whole contour of first three calibrating teeth there are small-size cutting-dividing grooves mutually arranged in staggered fashion on adjacent teeth. Depth of grooves exceeds rise of last cutting tooth by 0.1 - 0.2 mm. Pitch between cutting-dividing grooves is in range 2.8 - 3.0 mm. Spacing from bending point of polyhedral profile till first cutting-dividing groove is equal to 1.3 - 1.5 mm. Angle of profile of cutting-dividing grooves is equal to 45°. Bottom radius of cutting-dividing grooves is equal to 0.2 mm. Brach may be square, hexahedral or rectangular one.

EFFECT: enhanced accuracy of opening size, lowered roughness of broached surface.

2 cl, 4 dwg