Thread forming tap
AssigneeOsg Corporation
InventorsKensuke Hikosaka, Haruyasu Andoh
Life of this patent
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Abstract
A thread forming tap which is capable of reducing tapping torque as well as improving durability by avoiding an increase of an apparent area of margins of external thread that causes interference with a grinding stone. The thread forming tap has an external thread in a screw shape with alternately linked margins and reliefs for forming an internal thread by plastic deformation upon having the margins of the external thread bite into a surface of a prepared hole of a workpiece. A helix of the margins of the external thread is in a direction opposite to a direction of a helix of the external thread relative to an axis of the tap.
Claims9
A thread forming tap for forming an internal thread by plastic deformation, comprising:
- an external thread in a screw shape with alternately linked margins and reliefs;
- and
- an oil flute established on the external thread;
- wherein the external thread has a lead angle α and the margins of the external thread have a helix angle β inclined in a direction opposite to a direction of the helix of the external thread relative to an axis of the tap, and the helix angle β of the margins is larger than 0° and smaller than 10° or 4α;
- and
- wherein the oil flute is inclined relative to the axis of the tap where an angle and direction of the oil flute are identical to that of the margins on the external thread.
Dependencies are inferred from the claim text.