Tandem tap and method for cutting screw threads
AssigneeNorth American Tool Corporation
InventorsPenny E. Chapel, Ricky D. Rath
Life of this patent
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Abstract
A tandem tap for cutting screw threads into a bore comprises straight flutes with a spiral point along the front section for pushing the chips generated thereby forward and spiral flutes along the rear section for removing the chips generated thereby rearward in an opposite direction. The tap prevents build up of chips in the transition area between front and rear cutting sections of the tap.
Claims17
A tandem tap for cutting internal threads on an inner wall of a bore, the tap comprising:
- an elongate body for rotation about an axis, the elongate body extending between a workable end and a tip end, the elongate body including a first cutting section toward the tip end and a second cutting section between the first cutting section and the workable end, the workable end adapted to be worked for rotating the tandem tap, the first and second cutting sections including external threading of different thread characteristics wherein the first and second cutting sections are adapted to cuts threads having different characteristics;
- at least one first flute interrupting the external threading on the first cutting section, the first flute extending axially to the tip end, wherein when the first cutting section is cutting threads forming a plurality of chips, the chips are moved in a forward direction;
- and
- at least one spiral flute interrupting the external threading on the second cutting section, the spiral flute following a helical path leading toward the workable end, wherein when the second cutting section is cutting threads forming a plurality of chips, the chips are moved in a rearward direction opposite said forward direction.
A tandem tap for cutting threads into an inner wall of a bore by rotating the tandem tap inside the bore, the tandem tap comprising;
- first means for cutting a first screw threading into the inner wall, thereby producing a first set of chips;
- second means for simultaneously cutting a second screw threading into the inner wall in axial spaced relation to the first threading, the second screw threading being different thread characteristic than the first screw threading, thereby producing a second set of chips;
- and
- third means for moving the first set of chips in a forward direction for clearing the first set of chips;
- and
- fourth means for moving the second set of chips in a rearward direction opposite said forward direction for clearing the second set of chips.
A method for cutting threads into an inner wall of a bore by rotating a tandem tap inside the bore, the method comprising;
- cutting a first screw threading into the inner wall, thereby producing a first set of chips;
- simultaneously cutting a second threading into the inner wall in axial spaced relation to the first threading, the second screw threading being of a different thread characteristic than the first screw threading, thereby producing a second set of chips;
- and
- moving the first set of chips in a forward direction for clearing the first set of chips;
- and
- moving the second set of chips in a rearward direction opposite said forward direction for clearing the second set of chips.
Dependencies are inferred from the claim text.