Pot broach rings

A broach comprising a series of rings,

• radially inwardly extending teeth at the interior of said rings,
• said rings having flat front and rear sides adapted to abut in assembly,
• said rings having identically dimensioned exterior cylindrical surfaces provided with key-receiving recesses for receiving an aligning key,
• the front faces of all of said rings having concave annular surfaces of substantially identical radial width extending radially outwardly and rearwardly from the interior diameter thereof and curved forwardly to intersect the flat front sides thereof to define a front circle, to provide positive cutting rake and to form smoothly curved chip guiding gullets.
• the crests of the teeth of successive rings having uniformly decreasing radial spacing from the axes thereof from front to rear of the series of rings to provide for cutting tooth spaces in a work piece to a predetermined depth determined by the difference in radial spacing of the tooth crests between the leading and trailing rings of said series,
• the concave surfaces at the front of said rings having corresponding uniformly decreasing radial spacing from the axes thereof from front to rear to define front circles of decreasing radius from front to rear,
• all of said rings having identical inclined back slopes forming a continuous annular surface of revolution extending from the inside diameter of said rings intersecting the flat rear surface thereof to define therewith back circles, the diameter of said back circles on all of said rings being at least as great as the diameter of the front circle at the front of the leading ring of said series.