SCREW TAP Russian patent published in 1996 - IPC

FIELD: mechanical engineering. SUBSTANCE: screw tap is assembled. The rear, front and major corners are ground separately. The screw tap has guide portion with cylindric and treaded portion and working portion with cutting and calibrating portions. The portions are interconnected by way of fastening members. The pitch of the thread of the guide portion is equal to the pitch of the thread of the calibrating portion. The outer, mean, and inner diameters of the thread of the guide portion are less than nominal ones. The openings in both portions are through, their diameters are the same, and they are arranged over periphery forming different central angles. EFFECT: improved design. 2 cl, 2 dwg