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US 7,144,208 B2Granted
Low torque tap
AssigneeKennametal Inc.
InventorsWillard E. Henderer, Alan L. Barrows, Steven R. Burns, Dennis J. Greene
Life of this patent
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AssigneeKennametal Inc.
InventorsWillard E. Henderer, Alan L. Barrows, Steven R. Burns, Dennis J. Greene
Estimating the term…
A low torque tap includes a shank portion with a driving square and a thread cutting portion. The thread cutting portion includes a threaded body with one or more asymmetrical straight flutes that run essentially parallel to a longitudinal axis of the tap. The thread cutting portion also includes one or more short angular flutes or spiral points and a tapered chamfer. For tapping steel alloys, the cutting edges of the straight flutes and the spiral points have a rake or chordal hook angle of between about 5 and 15 degrees. For tapping ferrous materials, the tap is made from molybdenum-enriched high-speed steel and may be coated with a wear-resistant, friction-reducing layer. A second, outer layer, such as molybdenum disulfide, may be applied over the wear-reducing layer for further reduction in friction. For tapping non-ferrous materials, the tap may be coated with a layer of material containing carbon.
A low torque tap having a nominal diameter and comprising a shank portion with driving square and a thread cutting portion, said tap made of molybdenum enriched high speed steel, said tap coated with a layer of metal nitrides, carbides or carbonitrides, said metal chosen from one or more of the following:
A low torque tap having a nominal diameter and comprising a shank portion and a thread cutting portion, said tap made of a high speed steel, said tap having an asymmetrical straight flute and a spiral point formed at an angle with respect to a longitudinal axis of said tap forming a positive chordal hook angle, wherein said high speed steel consists essentially of about 0.8% to 1.3% carbon, about 3% to 4.5% chromium, about 6% to 10% molybdenum, about 0% to 5% tungsten, and about 1% to 3% vanadium, wherein said tap is coated with a layer of one of metal nitrides, carbides and carbonitrides, said metal chosen from one or more of the following:
A method of manufacturing a low torque tap having a nominal diameter, comprising the steps of:
A low torque tap comprising a shank portion with driving square and a thread cutting portion, said tap made of high speed steel, said tap coated with a layer of carbon, or carbon and one or more transition metals selected from the group IVa, Va and VIa of the Periodic Chart, said tap having an asymmetrical straight flute forming a positive rake angle between about 5 and 15 degrees, and a spiral point formed at an angle with respect to a longitudinal axis of said tap forming a positive chordal hook angle between about 5 and 15 degrees.
A low torque tap comprising a shank portion with driving square and a thread cutting portion, said tap made of a high speed steel, said tap having three asymmetrical straight flutes forming a positive rake angle between about 5 and 15 degrees, and a spiral point formed at a predetermined angle with respect to a longitudinal axis of said tap, said spiral point having a positive chordal hook angle, whereby the spiral point has a radius of approximately 19 to 23 percent measured relative to a major diameter of said tap, and whereby a centerline of the radius is offset from a centerline of said tap by approximately 22 to 32 percent measured relative to the major diameter of said tap.
Dependencies are inferred from the claim text.