TOOL FOR COARSE THREAD ROLLING IN BOLTS Russian patent published in 2008 - IPC B21H3/06 B23G7/02 

FIELD: technological processes.

SUBSTANCE: tool contains two screw threading dies, the working surface of which has three sections that gradually pass one into another. In every section alternating longitudinal cavities and protrusions are arranged. In the first section protrusions have the shape of triangle with angle of 90°÷100° at the top. In second section top part of protrusions has trapezoidal shape and corresponds to profile of bolt thread cavity. Height of specified top part makes 0.6÷0.7 from thread protrusion height. Lower part of protrusions in the second section has the shape of rectangle. In the third section profile of cavities corresponds to profile of thread protrusions. Depth of specified cavities makes 0.6÷0.7 from thread protrusion height.

EFFECT: increase of thread quality and tool resistance.

5 dwg