Axially compressible flexible tubing and method for making same
AssigneeCrushproof Tubing Company
InventorsVance M. Kramer, JR., Jonathan O. Rodebaugh
Life of this patent
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Abstract
A length of flexible helically corrugated rubber tubing is provided with certain characteristics that enable it to be axially compressed to less than half of its normal relaxed length using minimal force while still providing a high resistance to crushing. The tubing has a wall with a uniform thickness, the wall defining external and internal threads with a specially defined pitch and thread height related to the wall thickness.
Claims20
A length of flexible helically corrugated tubing formed of elastomeric material and having a wall of generally uniform thickness, the wall defining a continuous external thread and a corresponding continuous internal thread, the tubing having a normal relaxed length and an axial compressed length obtained when 25 pounds of axial force is applied to the tubing, wherein the ratio of the normal relaxed length to the axial compressed length is from about 5:1 to about 1.25:1.
A length of flexible helically corrugated tubing with an inner diameter from about 3.5 inches to about 6 inches and being formed of elastomeric material, the tubing defining a continuous external thread and a corresponding continuous internal thread, the tubing having a normal relaxed length and an axial compressed length obtained when 25 pounds of axial force is applied to the tubing, wherein the ratio of the normal relaxed length to the axial compressed length is from about 4:1 to about 2:1.
A method for making a length of flexible helically corrugated rubber tubing comprising the steps of:
- sliding an uncured rubber sleeve over a rotatable mandrel having a surface defining a continuous thread with a helical crest and a helical root,
- rotating the mandrel while wrapping a cord about the sleeve to press adjacent portions of the sleeve into the root to form helical convolutions in the sleeve,
- placing the mandrel, sleeve and cord as assembled into an oven to cure the sleeve and form a length of helically corrugated tubing,
- rotating the mandrel in a reverse direction and unwrapping the cord from the corrugated tubing, and
- removing the corrugated rubber tubing from the mandrel,
- wherein the helical convolutions formed in the tubing have a size sufficient to enable the tubing to exhibit a normal relaxed length and an axial compressed length obtained when 25 pounds of axial force is applied to the tubing such that the ratio of the normal relaxed length to the axial compressed length is from about 5:1 to about 1.25:1.
A method for making a length of flexible helically corrugated rubber tubing comprising the steps of:
- sliding an uncured rubber sleeve over a rotatable mandrel having a surface defining a continuous thread with a helical crest and a helical root, the thread having a pitch from about six to about ten times the thickness of the wall of the sleeve and a thread height from root to crest from about three to about five times the thickness of the wall of the sleeve,
- rotating the mandrel while wrapping a cord about the sleeve to press adjacent portions of the sleeve into the root to form helical convolutions in the sleeve,
- placing the mandrel, sleeve and cord as assembled into an oven to cure the sleeve and form a length of helically corrugated tubing,
- rotating the mandrel in a reverse direction and unwrapping the cord from the corrugated tubing, and
- removing the corrugated rubber tubing from the mandrel.
Dependencies are inferred from the claim text.