US 4,998,871 AGranted

Apparatus for deforming plastic tubing for lining pipe

AssigneePipe Liners, Inc.

InventorPatrick R. Ledoux

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Abstract

Apparatus is provided for lining a pipe wherein a thermoplastic liner is initially formed in a cylindrical shape with a diameter slightly larger than the internal diameter of the pipe. The liner is temporarily deformed at an elevated temperature to a different cross-section, preferably U-shaped, to reduce its overall cross-sectional dimension to facilitate insertion into the pipe to be lined. The deformation occurs with substantially comparable elongation of the pipe lining along its opposite sides thereby precluding variations in wall thickness and stress in the pipe. Once inserted, the liner is pressurized and reheated first to a temperature below its crystallization temperature to round the lining in the pipe and subsequently, further pressurized and reheated to a second temperature higher than the crystallization temperature to cause the liner to retain its original round shape.

Claims19

Dependent claims

Apparatus for producing a deformed pipe lining from a tubular pipe having a longitudinal axis and formed of a plastic material, comprising:

at least one rotatable backup roller disposed on an axis parallel to an axis of, and generally in opposition to, at least one rotatable pipe lining shaping roller said shaping roller having internal heating means;
the backup roller having a periphery generally centered at a plane of bilateral symmetry and adapted to engage a backup portion of the tubular pipe;
said shaping roller having a perimeter disposed generally on said plane of bilateral symmetry so that when said tubular cross-section passes generally between said backup and shaping rollers, a deformable portion of the tubular cross-section is depressed generally diametrically toward said backup portion thereof and substantially along the plane of bilateral symmetry, so that opposite side sections of the tubular cross-section bend into double wall configurations with a fold thereof juxtaposed to said opposite backup portion of the tubular cross-section, so that the cross-sectional configuration of the tubular portion is altered and reduced;
and
means for deflecting a portion of the tubular pipe opposite the deformable portion of the pipe inwardly toward the axis of the pipe and generally along the plane of symmetry thereof such that the deflected and deformed portions of the pipe have generally similar elongation.

2 more elements

Apparatus for producing a deformed pipe lining from a tubular pipe having a longitudinal axis and formed of a plastic material, comprising:

a device for preheating the pipe to a predetermined pressure;
a least one rotatable backup roller disposed on parallel to an axis of and generally in opposition to at least one rotatable pipe lining shaping roller;
the backup roller having a periphery generally centered at a plane of bilateral symmetry and adapted to engage a backup portion of the tubular pipe;
said shaping roller having a perimeter disposed generally on said plane of bilateral symmetry so that when said tubular cross-section passes generally between said backup and shaping rollers, a deformable portion of the tubular cross-section is depressed generally diametrically toward said backup portion thereof and substantially along the plane of bilateral symmetry, so that opposite side section of the tubular cross-section bend into double wall configurations with a fold thereof juxtaposed to said opposite backup portion of the tubular cross-section, so that the cross-sectional configuration of the tubular portion is altered and reduced;
and
internal for heating said shaping roller thereby to maintain the tubular pipe in the region of its deformation heated substantially to said predetermined temperature.

3 more elements

Dependencies are inferred from the claim text.