US3744290A — Production of intermittently fluted tubes

Claim 1

Independent Claim 163 words

In an apparatus for producing intermittently fluted tubing, the combination of a tube-drawing die forming a passage through which a tube is movable longitudinally in one direction and having a central longitudinal axis, said die having integral theRewith a series of fixed longitudinal ridges spaced around said axis and partly defining said passage, there being valleys between adjacent ridges, a mandrel movable along said axis and having integral therewith a series of fixed longitudinal peripheral ridges aligned with respective valleys in the die, said mandrel ridges forming valleys aligned with respective ridges of the die, and means for moving said mandrel along said axis in a direction opposite to said one direction and from a first position within the die, wherein said ridges are received in the respective aligned valleys but with a clearance sufficient to accommodate said movement of the tube through said die passage, to a second position wherein said mandrel ridges are withdrawn longitudinally from said valleys in the die.

Claim 2

Dependent Claim 163 words

In an apparatus for producing intermittently fluted tubing, the combination of a tube-drawing die forming a passage through which a tube is movable longitudinally in one direction and having a central longitudinal axis, said die having integral theRewith a series of fixed longitudinal ridges spaced around said axis and partly defining said passage, there being valleys between adjacent ridges, a mandrel movable along said axis and having integral therewith a series of fixed longitudinal peripheral ridges aligned with respective valleys in the die, said mandrel ridges forming valleys aligned with respective ridges of the die, and means for moving said mandrel along said axis in a direction opposite to said one direction and from a first position within the die, wherein said ridges are received in the respective aligned valleys but with a clearance sufficient to accommodate said movement of the tube through said die passage, to a second position wherein said mandrel ridges are withdrawn longitudinally from said valleys in the die.

Claim 3

Dependent Claim 158 words

In the production of intermittently fluted tubing, the method which comprises passing a tube lengthwise through a fluting zone while reducing the tube diameter and forming in the tube from a first sub-zone outside thereof a first series of deep longitudinal grooves and corresponding ridges spaced circumferentially around the tube and while forming in the tube from a second sub-zone, located inside the tube and within said first sub-zone, a second series of deep longitudinal grooves and corresponding ridges alternating with said grooves and ridges of the first series, and intermittently discontinuing said formation of said second series of grooves and corresponding ridges by moving said second sub-zone lengthwise of the tube to retract said second sub-zone from within the first sub-zone into an unreduced portion of the tube and while impressing in the tube from said first sub-zone, during passage of the tube therethrough, only shallow grooves aligned longitudinally with respective deep grooves of said first series.

Claim 4

Dependent Claim 158 words

In the production of intermittently fluted tubing, the method which comprises passing a tube lengthwise through a fluting zone while reducing the tube diameter and forming in the tube from a first sub-zone outside thereof a first series of deep longitudinal grooves and corresponding ridges spaced circumferentially around the tube and while forming in the tube from a second sub-zone, located inside the tube and within said first sub-zone, a second series of deep longitudinal grooves and corresponding ridges alternating with said grooves and ridges of the first series, and intermittently discontinuing said formation of said second series of grooves and corresponding ridges by moving said second sub-zone lengthwise of the tube to retract said second sub-zone from within the first sub-zone into an unreduced portion of the tube and while impressing in the tube from said first sub-zone, during passage of the tube therethrough, only shallow grooves aligned longitudinally with respective deep grooves of said first series.

Claim 5

Dependent Claim 47 words

The combination according to claim 1, in which the die has an entrance end and an exit end, the ridges and valleys of the die sloping toward said central axis in the direction from said entrance end to said exit end, whereby the die effects said tube-drawing.

Claim 6

Dependent Claim 74 words

The combination according to claim 3, comprising also a said tube extending through said die passage and containing the mandrel, the tube at said entrance end having an inner diameter sufficient to provide a clearance between the inner wall of the tube and said ridges of the mandrel, the tube at said exit end having its inner diameter reduced sufficiently for said mandrel ridges to engage and indent the inner surface of the tube.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	1976-07-09	1977-01-08	1977-07-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	1980-07-09	1981-01-08	1981-07-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	1984-07-09	1985-01-08	1985-07-10	$7700.00	Window Closed / Lapsed

Production of intermittently fluted tubes

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