Method of forming helically corrugated tubing
AssigneeSpiral Tubing Corporation
InventorRobert W. Perkins
Life of this patent
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Abstract
Helical corrugations are formed in a tube having a cylindrical wall by generating pressure radially of the unsupported tube wall at localized areas distributed around the tube circumference. While the radial pressure is being generated, twisting of the tube about its own axis is initiated and as a result, radial deformation of the unsupported tube wall takes place. By controlling the axial length of the tube while it is twisted, the radial deformations develop into flutes which grow axially along a selected helical path in the tube wall.
Claims17
A method of helically corrugating a section of deformable tube comprising the steps of:
- providing a section of deformable tube having a cylindrical wall without deformations between the axial tube ends;
- twisting one axial end of the tube section about the tube axis relative to the other axial end of the section;
- generating localized pressure radially of the cylindrical wall at areas of the wall which are unsupported and which are distributed around the otherwise cylindrical tube while twisting the one axial end of the tube section relative to the other axial end to reduce the resistance to torsion and initiate radial deformation of the tube wall at the pressurized areas in conjunction with the step of twisting;
- and
- controlling the axial length of the tube section during the step of twisting to cause the radial deformations to grow from the pressurized areas axially along a selected helical path in the cylindrical tube wall.
A method of forming helical corrugations in the wall of a deformable tube having a generally circular cross-section comprising the steps of:
- applying radially directed pressure to the tube wall at localized and unsupported areas around the circumference of the tube, the areas corresponding to the flutes desired in the corrugations, to be formed;
- and
- initiating twisting of the deformable tube about its longitudinal axis while the radially directed pressure is applied to the localized areas to initiate deformation of the tube wall along helical lines emanating from the locally pressurized areas.
Dependencies are inferred from the claim text.