A corrugator for an extrusion system for shaping a tubular plastic product, having a multiplicity of mould blocks, a guide track, along which the mould blocks are guided in each case in pairs during the operation of the corrugator from a starting region of the guide track towards an outlet region of the guide track, a first return track, along which the mould blocks are guided during the operation of the corrugator from the outlet region towards the starting region, and a second return track, with the aid of which individual mould blocks can be removed from the first return track and/or can be inserted into the latter during the operation of the corrugator.

A method of forming a corrugated fluoropolymer tube is disclosed. The method comprises the step of providing a tube comprising extruded fluoropolymer without corrugations or convolutions disposed on a mandrel. The mandrel has a first cylindrical portion and a flaring portion that extends to a second cylindrical portion, the second portion having an outer diameter which is larger than an outer diameter of the first portion. The method also includes the step of moving the tube on a longitudinal axis along the mandrel thereby forcing an outer surface of the tube into flights disposed at a pitch angle on a plurality of thread rollers which are rotating, the plurality of thread rollers adjacent to and circumferentially distributed around the flaring portion and/or second cylindrical portion of the mandrel, wherein external force is exerted on the outer surface of the tube to form corrugations having adjacent peaks and roots.

A system and method for replacing or substituting mold blocks in a corrugator, the corrugator comprising first and second tracks for carrying respective chains of mold blocks, each of the tracks comprising return tracks, wherein the system advances replacement mold blocks towards the return tracks to displace corresponding mold blocks in the mold block chains while the corrugator is in production and while the mold block chains are in motion.

A method of continuously forming an axially extensible and retractable hose comprising: continuously forming an axially extending helix with axially spaced reinforcing coils from extruded thermoplastic material having a uniform cross-section along its length; and continuously bridging between an adjacent pair of the reinforcing coils with a continuous web of extruded thermoplastic material of substantially uniform width and relatively thin cross-section to form a continuous, helically extending sidewall, with the web having one of two opposite edge regions bonded continuously to a relatively flat outer bonding surface of a radially outwardly located portion of one of the adjacent pair of reinforcing coils, with the web having the other of the edge regions bonded continuously to a relatively flat inner bonding surface of a radially inwardly located portion of the other of the pair of reinforcing coils, and with the edge regions continuously radially separated from each other by the helix.

This disclosure relates generally to corrugated pipe, and more particularly to corrugated pipe with a reinforcing stiffener. The corrugated pipe may include an axially extended bore defined by a corrugated outer wall having axially adjacent, outwardly-extending corrugation crests, separated by corrugation valleys. In some embodiments, a stiffener may be positioned within the corrugation valleys. In other embodiments, a stiffener may be positioned within the corrugation crests.

A corrugated pipe includes a corrugated pipe body circumscribing a hollow conduit and including alternating ribs and valleys extending along a longitudinal axis between a first end and a second end thereof. An electrically conductive wire is embedded in the corrugated pipe body, so that the wire spans adjacent ribs and valleys and extends substantially parallel to the longitudinal axis between the first and second ends.

The present invention involves a fabrication of plastic-tube-screen-fill using plastic tubes. The plastic-tube-screen-fill consists of several plastic tubes suspended to between top and bottom ring-shaped hole perforated frames in the shape of a rectangular thin plate as a vertical string screen. The top and bottom ring-shaped hole perforated frames are in same configuration to be used in two ways and fabricated by assembling a cup-shaped hole perforated frame and tube-holder-frame. The tube-holder-frame is a male push-fit band connector with several short solid rods positioned and fixed on band for push-fitting into the cup-shaped holes on the cup-shaped hole perforated frame. The solid rod on tube-holder-frame has a male push-fit connector on its lower part to be push-fitted into one edge of tube. The tubes used in the present invention are spiral corrugated tubes. Fabrication and assembling method of perforated frames, tube-holder-frames, and spiral corrugated tubes are described in this invention.

A seamless convoluted hose assembly. The assembly includes: a tubular inner liner having an outer surface, an inner surface, and an inner liner wall therebetween which defines a passageway. The assembly further includes a helical coil or a plurality of annular loops which produce convolutions in the outer surface of the tubular liner when the tubular inner liner is forced through the helical coil or plurality of loops under heat and pressure.

A method of continuously forming an axially extensible and retractable hose comprising the steps of continuously forming an axially extending helix with axially spaced reinforcing coils from extruded thermoplastic material having a uniform cross-section along its length; and continuously bridging between an adjacent pair of the reinforcing coils with a continuous web of extruded thermoplastic material of substantially uniform width and relatively thin cross-section to form a continuous, helically extending sidewall, with the web having one of two opposite edge regions bonded continuously to a relatively flat outer bonding surface of a radially outwardly located portion of one of the adjacent pair of reinforcing coils, with the web having the other of the edge regions bonded continuously to a relatively flat inner bonding surface of a radially inwardly located portion of the other of the pair of reinforcing coils, and with the edge regions continuously radially separated from each other by the helix.

Plastic tubing including a thermoplastic ribbon helically wrapped and heat bonded to itself to form a tubing wall and a thermoplastic reinforcement located helically around and along the tubing wall. At least a thickness of the tubing wall or a size of the thermoplastic reinforcement is varied along the tubing wall.