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.

Pipe corrugators having opposed series of pushed mold blocks forming a moving mold tunnel are subject to significant thermal expansion and are designed with a thermal expansion gap. The present invention provides a method and apparatus for measuring changes in this expansion gap and preferably recognizing potential thermal issues before serious problems occur. A sensor is provided adjacent a mold block drive that preferably detects a time duration between sensing a trailing portion of a lead mold block and a leading edge of a following mold block separated from the lead mold block by the thermal expansion gap. This time duration in combination with a speed of the pushed mold blocks is used to calculate the size of the thermal expansion gap.

Pipe corrugators having opposed series of pushed mold blocks forming a moving mold tunnel are subject to significant thermal expansion and are designed with a thermal expansion gap. The present invention provides a method and apparatus for measuring changes in this expansion gap and preferably recognizing potential thermal issues before serious problems occur. A sensor is provided adjacent a mold block drive that preferably detects a time duration between sensing a trailing portion of a lead mold block and a leading edge of a following mold block separated from the lead mold block by the thermal expansion gap. This time duration in combination with a speed of the pushed mold blocks is used to calculate the size of the thermal expansion gap.

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 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 plastic corrugated tube having corrugations distributed over its length and a longitudinal slit running along a lateral longitudinal line is provided. The corrugated tube can be converted into an open position by opening the longitudinal slit and into a closed position in which edge regions of the corrugated tube overlap, wherein the corrugated tube is elastically prestressed toward its closed position. The corrugations on the edge region of the corrugated tube, which in the closed position lies radially below the other edge region of the corrugated tube, are offset radially inwards within a predefined circumferential region with respect to the corrugations outside this circumferential region and are designed such that, in the closed position, they are in engagement with the radial underside of the corrugations of the other edge region, which corrugations engage over them such that they are mutually displaceable in the circumferential direction.

A plastic corrugated tube having corrugations distributed over its length and a longitudinal slit running along a lateral longitudinal line is provided. The corrugated tube can be converted into an open position by opening the longitudinal slit and into a closed position in which edge regions of the corrugated tube overlap, wherein the corrugated tube is elastically prestressed toward its closed position. The corrugations on the edge region of the corrugated tube, which in the closed position lies radially below the other edge region of the corrugated tube, are offset radially inwards within a predefined circumferential region with respect to the corrugations outside this circumferential region and are designed such that, in the closed position, they are in engagement with the radial underside of the corrugations of the other edge region, which corrugations engage over them such that they are mutually displaceable in the circumferential direction.

The invention relates to a manufacturing method and a manufacturing equipment for a corrugated net. The manufacturing method comprises steps of: injecting a thermoplastic plastic mesh material, the plastic mesh material having an injection temperature; directly reducing a temperature of the plastic mesh material from the injection temperature to a moldable temperature; and pressing the plastic mesh material with the moldable temperature to cause the plastic mesh material with the moldable temperature to form creases. The invention is capable of reducing manufacturing procedures and time by directly adjusting the injected plastic mesh material to the moldable temperature and pressing to form creases without requiring heating equipment, and the moldable temperature of the overall plastic mesh material is uniformly set to be capable of improving an effect of forming corrugated structure for the mesh material.

The invention relates to a manufacturing method and a manufacturing equipment for a corrugated net. The manufacturing method comprises steps of: injecting a thermoplastic plastic mesh material, the plastic mesh material having an injection temperature; directly reducing a temperature of the plastic mesh material from the injection temperature to a moldable temperature; and pressing the plastic mesh material with the moldable temperature to cause the plastic mesh material with the moldable temperature to form creases. The invention is capable of reducing manufacturing procedures and time by directly adjusting the injected plastic mesh material to the moldable temperature and pressing to form creases without requiring heating equipment, and the moldable temperature of the overall plastic mesh material is uniformly set to be capable of improving an effect of forming corrugated structure for the mesh material.

A flexible hose including a first tubular element of corrugated shape having in longitudinal cross-section a series of outer crests and a second tubular element of lightweight polymeric material externally associated with said first tubular element so as to fill at least partially a corresponding series of troughs alternately shaped by said outer crests.