Abstract: In the manufacture of double-walled corrugated extruded pipe it is desirable to form an integral connecting cuff that is of a single wall thickness and typically of a large diameter. The mold blocks and process parameters for forming of the cuff as part of an otherwise double-walled pipe requires a transition as the cuff moves past the die outlets. The present invention allows for accurate sensing and control of air pressure and temperature as the cuff moves past the die outlets. Improvements in both the die tooling and the method of manufacture are disclosed.

Abstract: A multiple lumen hose includes a generally circumferential base wall. A plurality of corrugations extend radially outward from the base wall. A septum is disposed interior to the base wall such as to divide the interior of the base wall into at least a first lumen and a second lumen. A first scallop extends outward from the circumferential base wall between adjacent corrugations. A second scallop extends outward from the circumferential base wall between adjacent corrugations.

Abstract: A process for making an embossed web includes providing a precursor web a first forming structure having a plurality of discrete first forming elements and a first pressure source and applying pressure between the first pressure source and the first forming structure to force the precursor web to conform to the first forming elements of to form a first embossed web having a plurality of first discrete extended elements. The first embossed web is then provided between a second forming structure having a plurality of discrete second forming elements and a second pressure source and pressure is applied between the second pressure source and the second forming structure to force the first embossed web to conform to the second forming elements to form a second embossed web having a plurality of second discrete extended elements. The resulting embossed web has a plurality of first and second discrete extended elements.

Abstract: A method and an apparatus for producing an endless double-walled pipe having corrugated pipe sections and sleeve pipe sections are described. The production is effected by extrusion of an outer tube (Sa), forming the outer pipe of the double-walled pipe, and of an inner tube (Si), forming the inner tube of the double-walled pipe, in a molding passage (10) having sections with a corrugated molding surface and a smooth cylindrical sleeve molding surface. To shape the sleeve section, the outer tube is extruded into the sleeve molding surface and is brought into contact with the sleeve molding surface. The inner tube (Si) is then extruded into the outer tube (Sa), already in contact over the entire axial length of the sleeve molding surface, and is brought in the process into contact with the inner side of said outer tube (Sa) that is in contact.

Abstract: An extrudable polyvinyl chloride composition comprising from 80 to 99.9 percent by weight polyvinyl chloride for use in extruding a first part and a second part, wherein a fusion joint between the first extruded part and the second extruded part is formed by: A) composition at least a portion of a first terminal edge of the first extruded part and a first terminal edge of the second extruded part; B) engaging the melted terminal edges; and C) maintaining pressure between the engaged terminal edges to create a fused joint having a strength that is at least 50% of the tensile strength of the extruded part as measured by ASTM D638-2a. The extruded parts can be pipe sections.

Abstract: Into a molding path moving in a direction of conveyance is extruded an internal tube from a first extruder and an external tube from a second extruder, the external tube being concentric with the internal tube. During the production of a normal compound pipe, the smooth internal tube is welded together with the external tube which is provided with transverse grooves. At the transition from the normal compound pipe to the expanded pipe socket, the extruder speed of the first extruder is increased from a speed n1,1 to a speed n1,2. During the production of the pipe socket, the speed of the first extruder is reduced to a speed in1,3, wherein n1, 2>n1,3>n1,1 applies.

Abstract: An extrudable polyvinyl chloride composition comprising from 80 to 99.9 percent by weight polyvinyl chloride for use in extruding a first part and a second part, wherein a fusion joint between the first extruded part and the second extruded part is formed by: A) composition at least a portion of a first terminal edge of the first extruded part and a first terminal edge of the second extruded part; B) engaging the melted terminal edges; and C) maintaining pressure between the engaged terminal edges to create a fused joint having a strength that is at least 50% of the tensile strength of the extruded part as measured by ASTM D638-2a. The extruded parts can be pipe sections.

Abstract: A device for making a profiled insulation having an extrusion die with an extrusion tip and a polymer chamber surrounding the extrusion tip. The polymer chamber has at least one air chamber therein. The air chamber is held in place and coupled to the outside of the extrusion die by a vertical fin extending outwards from the extrusion tip. When molten polymer flows through the polymer chamber around the air chamber, an opening is introduced into the polymer such that the profiled insulation is formed as the polymer exits the extrusion die, having a longitudinal cavity therein corresponding to the location of the opening formed by the at least one air chamber.

Abstract: A piece of corrugated pipe cut from a longer length of pipe is provided with a pipe coupling part by subjecting one or more of the corrugation crests on the pipe to heat and pressure. This reshapes the one or more corrugations to form a seal receiving recessed spigot on the piece of pipe.

Abstract: A cable and method of forming the cable are presented. The cable contains twisted wire pairs disposed in a cavity defined by a jacket. Each wire has a conductor and an insulator surrounding the conductor. The cable may also contain a spline that separates the twisted wire pairs. At least one of the insulators or the jacket is helically corrugated such that ridges extend radially inward or outward. The ridges of the insulators may be the same or different. The cable is extruded from an extruder. The jacket may contain corrugations after being extruded by the extruder. The cable may be passed through dies to form a helically corrugated jacket. The jacket heated by a heater prior to being passed through the dies, or may pass through the dies while still hot from the extruder.

Abstract: An extrudable polyvinyl chloride composition comprising from 80 to 99.9 percent by weight polyvinyl chloride for use in extruding a first part and a second part, wherein a fusion joint between the first extruded part and the second extruded part is formed by: A) composition at least a portion of a first terminal edge of the first extruded part and a first terminal edge of the second extruded part; B) engaging the melted terminal edges; and C) maintaining pressure between the engaged terminal edges to create a fused joint having a strength that is at least 50% of the tensile strength of the extruded part as measured by ASTM D638-2a. The extruded parts can be pipe sections.

Abstract: An extrudable polyvinyl chloride composition comprising from 80 to 99.9 percent by weight polyvinyl chloride for use in extruding a first part and a second part, wherein a fusion joint between the first extruded part and the second extruded part is formed by: A) composition at least a portion of a first terminal edge of the first extruded part and a first terminal edge of the second extruded part; B) engaging the melted terminal edges; and C) maintaining pressure between the engaged terminal edges to create a fused joint having a strength that is at least 50% of the tensile strength of the extruded part as measured by ASTM D638-2a. The extruded parts can be pipe sections.

Abstract: A mold cooling system is provided for cooling a polymer product shaped in a mold. The mold cooling system includes a moving manifold having a cooling fluid supply and a cooling fluid return; and a mold housing having a mold surface that defines a cavity. The mold housing has a connector configured to receive the cooling fluid supply and cooling fluid return of the moving manifold; and a passageway that extends through the mold housing adjacent to the mold surface, the passageway connecting the cooling fluid supply and the cooling fluid return when the moving manifold is received in the connector. A method is also provided for cooling an extruded, blow-molded product before the product is released from a mold.

Abstract: Into a molding path moving in a direction of conveyance is extruded an internal tube from a first extruder and an external tube from a second extruder, the external tube being concentric with the internal tube. During the production of a normal compound pipe, the smooth internal tube is welded together with the external tube which is provided with transverse grooves. At the transition from the normal compound pipe to the expanded pipe socket, the extruder speed of the first extruder is increased from a speed n1,1 to a speed n1,2. During the production of the pipe socket, the speed of the first extruder is reduced to a speed in1,3, wherein n1,2>n1,3>n1,1 applies.

Abstract: In at least one method for manufacturing a double-walled, thermoplastic tube with a connecting sleeve, which enables precise and complete moulding of the connecting sleeve by simple means, it is provided that a) a first tube (1) is extruded into a mould tunnel (4) comprising at least one row of moulds (5) guided on a path, b) the first tube (1) is given a corrugated shape in at least one first section and expanded into a connecting sleeve in at least one second section, c) a second tube (6) is extruded into the first tube and pressed against the corrugation troughs (8) of the first tube (1), d) while the first tube (1) is being given a corrugated shape and the second tube (6) extruded into the first, the space (A) between the two tubes (1, 6) is subjected to a pressure p1 that is above atmospheric pressure, e) the space (A) between the two tubes (1, 6) is subjected, at a specified time before or after expansion of the first tube (1) into a connecting sleeve, to an essentially constant pressure p2?p1 above atm

Abstract: A method and apparatus for performing a manufacturing operation at a plurality of locations along the length of a previously fabricated flexible conduit. The apparatus comprises a driving mechanism, a manufacturing station, and a support device. The conduit is first fed through the manufacturing station. The manufacturing station then performs the manufacturing operation at a plurality of locations along the length of the conduit. The support device within the conduit is not attached to any other structure and provides structural support at the manufacturing station during the manufacturing operation and remains at a generally fixed axial and functional location while the conduit continues to move axially.

Abstract: In at least one method for manufacturing a double-walled, thermoplastic tube with a connecting sleeve, which enables precise and complete moulding of the connecting sleeve by simple means, it is provided that a) a first tube (1) is extruded into a mould tunnel (4) comprising at least one row of moulds (5) guided on a path, b) the first tube (1) is given a corrugated shape in at least one first section and expanded into a connecting sleeve in at least one second section, c) a second tube (6) is extruded into the first tube and pressed against the corrugation troughs (8) of the first tube (1), d) while the first tube (1) is being given a corrugated shape and the second tube (6) extruded into the first, the space (A) between the two tubes (1, 6) is subjected to a pressure p1 that is above atmospheric pressure, e) the space (A) between the two tubes (1, 6) is subjected, at a specified time before or after expansion of the first tube (1) into a connecting sleeve, to an essentially constant pressure p2?p1 above atm

Abstract: A twin-wall pipe comprises an internal pipe and an external pipe. The external pipe is corrugated, having elevations and troughs. The twin-wall pipe is further provided with a socket. In a transition portion towards the twin-wall pipe and the socket, provision is made for at least one overflow passage which interconnects the clearance between the external pipe and internal pipe in the vicinity of the transition portion and an adjacent elevation.

Abstract: A vulcanization mold (2) includes several segments (8a, 8b; 10a, 10b; 12a, 12b; 14a, 14b) which define two end profiles (8, 10) and two inner profile shells (12, 14) having concave surfaces. With synchronous movement sequences, which take place via linear controls from both ends, the segments (8a, 8b; 10a, 10b; 12a, 12b; 14a, 14b) are moved together under simultaneous shaping pressure. The outer profile shells (8, 10) pass through twice the distance as the inner profile shells (12, 14). The forming of the work blank (20) is completed via the shaping pressure when the mold (2) has reached the closed position. Preferably the upper profile half shells (8a, 10a, 12a, 14a) and the lower profile segments (8b, 10b, 12b, 14b) are operatively connected to each other via toothed racks (40a, 46a, 48a, 54a; 40b, 46b, 48b, 54b) and gear wheels (42a, 44a, 50a, 52a; 42b, 44b, 50b, 52b) including additional sets of teeth (42a?, 50a?; 42b?, 50b?).

Abstract: The present invention resides in a boot seal for use in sealing a joint. The joint comprises first and second relatively movable parts. The boot seal is configured in the form of a sleeve to extend between and around the vehicle relatively movable parts. The sleeve has a laminate wall which comprises at least two layers of thermoplastic elastomeric material which are bonded together. At least one of the layers is a stretch-toughenable polyester thermoplastic elastomer which has been diametrically stretched in an amount effective to increase the toughness of said one layer. The laminate wall has a percent elongation to rupture of at least 100, and a flexural modulus which is less than 100,000 psi. The laminate wall preferably has a puncture resistance of at least 50 Newtons/mm wall thickness.

Abstract: A method and an apparatus for the manufacture of pipes of thermoplastics with transverse profile features comprises mold segment halves which are circulated by twos on a molding path. A conveying device of the type of a gantry crane is provided for recirculation of the mold segment halves. On a conveying bridge that bridges the molding path, provision is made for two conveying carriages, which are movable in opposite directions and cross-wise of the direction of production and which have mounted on them a downward conveying arm with a holding device for a respective mold segment half. Provided downstream of the downstream end of the molding path are parking positions for additional mold segment halves, those of which that are closest to the molding path being carriages which are movable out of the path of displacement of the conveying arms.

Abstract: Pipe molding apparatus having a molding mold tunnel includes an upstream (3) and at least one downstream mold block (7). Each mold block (3, 5, 7) comprises mold block sections which close with one another to form the pipe and which open relative to one another to release the pipe. The mold blocks (3, 5, 7) move downstream of the apparatus together with one another when forming the pipe and move upstream separately from one another when releasing the pipe which cools and shrinks in both diameter and length in the mold tunnel. Each mold block (3, 5, 7) has a hollow pipe forming region with the pipe forming region of the downstream mold block being decreased in both diameter and length relative to the pipe forming region of the upstream mold block (3) to compensate for the plastic shrinkage.

Abstract: A plastic hollow preform is drawn through a mold passage formed in a closed mold by applying a generally constant suction to a downstream end of a conduit having an upstream end connected to an output end of the mold passage. A flow cross section of the conduit is varied between its upstream and downstream ends so as to vary a rate at which the preform is drawn through the passage by the suction. The flow cross section is varied by displacing a valve element in the conduit between positions in which it differently blocks flow through the conduit.

Abstract: In a method for manufacturing a double-walled, thermoplastic tube with a connecting sleeve, which enables precise and complete moulding of the connecting sleeve by simple means, it is provided that a) a first tube (1) is extruded into a mould tunnel (4) comprising at least one row of moulds (5) guided on a path, b) the first tube (1) is given a corrugated shape in at least one first section and expanded into a connecting sleeve in at least one second section, c) a second tube (6) is extruded into the first tube and pressed against the corrugation troughs (8) of the first tube (1), d) while the first tube (1) is being given a corrugated shape and the second tube (6) extruded into the first, the space (A) between the two tubes (1, 6) is subjected to a pressure p1 that is above atmospheric pressure, e) the space (A) between the two tubes (1, 6) is subjected, at a specified time before or after expansion of the first tube (1) into a connecting sleeve, to an essentially constant pressure p2≦p1 above atmospheric

Abstract: A method for continuously forming molded parts includes providing an extruder; directing a hollow column of plastic material from the extruder; providing a plurality of die blocks each including planar end segments having differing geometry and joined by the intermediate convoluted segments; continuously moving such die blocks for receiving and forming the hollow column into strut boots with planar end segments and intermediate convoluted segments and advancing the shaped column of plastic material from the continuously moving die blocks and providing a cutter synchronized to the movement of the shaped column for separating the planar end segments to form one or more parts having planar end segments of the same or differing geometry in each part or with differing geometry from part to part.

Abstract: In a process and an apparatus for making a plastic sleeve (56), plastic is fed into an extruder die (216). The plastic is extruded from the extruder die (216) as a molten plastic stream into a mold cavity (272) having an inner wall (270) with dimensions greater than the outside dimensions of the molten plastic stream. A first end (274) of the inner wall (270) includes a first projection (282) extending radially inward of the mold cavity (272) and circumferentially completely around the mold cavity (272). The molten plastic stream is vacuum expanded radially against the inner wall (270) and around the projection (282) to form a plastic sleeve (56) with a circumferential rib (74) and a aligned external first groove (92) at one end (60) of the sleeve (56).

Abstract: A method and apparatus for producing an extruded product includes a machine that cooperates with an extruder. The machine is commonly used as a corrugator and the extruded product is often corrugated piping. The machine has a frame supporting a trackway in a continuous path. A plurality of mold block assemblies travel about the continuous path to form a mold tunnel along a portion of the continuous path. The mold block assemblies include a carriage connected by at least one guide and linear bearings to a pair of mold holders. The mold holders are connected to at least one pair of opposing mold blocks. Guides and directors position the mold block pairs relative to one another while the assemblies travel along the continuous path. As the holders, and thus the mold block halves, are linearly displaceable from one another, the halves may meet to form the mold tunnel and separate to allow removal of the extruded product.

Abstract: A process for making a plastic tube having a variable diameter comprises the following steps. A plastic is obtained. The plastic is fed into an extruder die (216). The plastic is extruded as a tubular molten plastic stream (262) into a mold cavity (218) having an inside diameter greater than the diameter of the tubular molten plastic stream (262). The mold cavity (218) inside diameter varies longitudinally along the length of the mold cavity (218). The tubular molten plastic stream (262) is vacuum expanded radially against the mold cavity inner wall (290). The wall thickness of the tubular molten plastic stream (262) is varied during extrusion at locations longitudinally along the stream (262).

Abstract: The present invention resides in that a plurality of pre-molded inner ducts are fed to a cross-head die, and a melted outer duct is extruded around the inner ducts from the cross-head die, and then the pre-molded inner ducts and a melted outer duct are supplied into the corrugated tunnel of a molding die in which a melted outer duct is molded to have corrugations, thus producing a multiple channel duct assembly which includes a plurality of elongated inner ducts and a corrugated outer duct which encircles the inner ducts over their entire length to retain them. This method of continuously manufacturing a multiple channel duct assembly by using an extrusion molding machine with a cross-head die and a molding means has not been known heretofore.

Abstract: A branched pipe (5) is manufactured by continuous extrusion in such a manner that a manifold (5a) of a branched pipe (5) is manufactured by extruding plastic material into the space defined by moving chill moulds (1, 2) and a mandrel (10) arranged therein with an extruder (4). The manifold (5a) is provided with branch pipes (5b) simultaneously with the extrusion thereof.

Abstract: In a process for the production of corrugated plastic tubes an extrusion device passes plastic material into a perpendicularly arranged injection head for injecting the plastic material into a perpendicularly arranged mold section comprising at least two pairs of movable mold jaws arranged in axially mutually superposed relationship. A drive device is associated with each pair of mold jaws for displacement thereof in the radial and axial directions.

Abstract: Thermoplastic multilayer composite, particularly in the form of a multilayer hose, a multilayer pipe or a multilayer container, containing at least one intermediate layer made of a molding compound on the basis of ethylene/vinyl alcohol copolymers between layers made of molding compounds on the basis of polyamide, the intermediate layer being bonded via at least one adhesion-promoting layer made of a molding compound on the basis of polyamide selected from the group of copolyamide 6/12, block copolyamide 6/12, polyamide 612, polyamide 610, a mixture of polyamide 6 and polyamide 12 with compatibilizer, a mixture of polyamide 6 and polyamide 11 with compatibilizer, with at least one neighboring layer made of a molding compound on the basis of polyamide 12, polyamide 11, polyamide 1010, polyamide 1012, or polyamide 1212.

Abstract: In a process and an apparatus for making a plastic sleeve (56), plastic is fed into an extruder die (216). The plastic is extruded from the extruder die (216) as a molten plastic stream into a mold cavity (272) having an inner wall (270) with dimensions greater than the outside dimensions of the molten plastic stream. A first end (274) of the inner wall (270) includes a first projection (282) extending radially inward of the mold cavity (272) and circumferentially completely around the mold cavity (272). The molten plastic stream is vacuum expanded radially against the inner wall (270) and around the projection (282) to form a plastic sleeve (56) with a circumferential rib (74) and a aligned external first groove (92) at one end (60) of the sleeve (56).

Abstract: Bellows-shaped pleats are formed by a corrugator on bellows portions of a cylindrical hose formed by extrusion from a thermoplastic resin. The height of the pleats of the hose is uniform in a circumferential direction, and the numbers of the pleats on the bellows portions are different from one another. When water is encapsulated in the hose and the hose is heated, the pleats having different circumferential shapes from one another are stretched by the pressure of a vapor generated from the water, whereby the bellows portions of the hose are bent automatically with the portions corresponding to generating lines and free from the pleats being on an inner side. The bending angle at that time is determined depending on the numbers of the pleats. Thus, it is possible to provide a resinous hose at a low cost, which is formed, so that even if the hose is used in a high-temperature and a high-pressure environment, the bent shape of the hose can be maintained over a long period of time.

Abstract: For the continuous manufacture of a twin-wall pipe having a pipe socket and consisting of a smooth internal tube and an external tube, which is welded together therewith and provided with transverse grooves, two extruders are provided, which extrude an external tube and an internal tube via a joint crosshead. Switches are provided for the production of a pipe socket, by means of which the speed of the extruder is modified in such a way that the mass flow of the melt of plastic material for the production of the external tube is reduced during the production of the pipe socket and/or the mass flow for the production of the inner tube is augmented.

Abstract: Bellows-shaped pleats are formed by a corrugator on bellows portions of a cylindrical hose formed by extrusion from a thermoplastic resin. The height of the pleats of the hose is uniform in a circumferential direction, and the numbers of the pleats on the bellows portions are different from one another. When water is encapsulated in the hose and the hose is heated, the pleats having different circumferential shapes from one another are stretched by the pressure of a vapor generated from the water, whereby the bellows portions of the hose are bent automatically with the portions corresponding to generating lines and free from the pleats being on an inner side. The bending angle at that time is determined depending on the numbers of the pleats. Thus, it is possible to provide a resinous hose at a low cost, which is formed, so that even if the hose is used in a high-temperature and a high-pressure environment, the bent shape of the hose can be maintained over a long period of time.

Abstract: A corrugated fuel tube is manufactured by extruding an inner single layer or multilayer of a resin of high fuel impermeability, extruding an outer single layer or multilayer of a thermoplastic resin so as to cover the inner layer to form a tube having a multi-layered wall, and corrugating the tube along at least a part thereof. The surface treatment is preferably given to an outer peripheral surface of the inner layer to ensure an improved adhesion between the inner and outer layers. The tube can be made without presenting any problem caused by a difference in melt viscosity between the materials forming its inner and outer layers.

Abstract: A plastic pipe has a multiple layer wall construction including major and minor wall portions. The major wall portions are formed with first corrugations and are separated from one another by the minor wall portions which are formed with second corrugations and a bowed wall part which is of the same diameter as the first corrugations. The second corrugations are smaller in diameter than both the first corrugations and the bowed wall pipe. The wall construction is cut at the bowed wall part to produce two pipe sections which couple with one another. One of those pipe sections has an open ended bell converted from the bowed wall pipe and the other pipe section has a male spigot formed by the second corrugations of the wall construction.

Abstract: A mold block which is used in a moving mold tunnel comprises first and second mold block sections which meet at their parting faces to close the mold block. Each mold block section has a product shaping interior surface and an air movement passage having an entrance at the base of each mold block section, a first opening to the interior surface and a second opening to the parting face of each mold block section. An air flow controller is provided between the parting face opening and the interior surface opening of the passage in the first mold block section and an air flow controller is provided between the entrance and the interior surface opening in the passage in the second mold block section.

Abstract: A thermoplastic multilayer composite, and articles made therefrom, which has at least one layer I of a thermoplastic molding composition, at least one layer II of a further thermoplastic molding composition, bonded together with at least one layer of an adhesion promoter disposed between at least one layer I and at least one layer II. The adhesion promoter is at least 5% by weight of a graft copolymer prepared from 0.5 to 25% by weight, based on the total amount of graft copolymer, of a polyamine having at least 4 nitrogen atoms and having a number average molecular weight Mn of at least 146 g/mol, and polyamide-forming monomers selected from lactams, &ohgr;-aminocarboxylic acids, equimolar mixtures of diamines and dicarboxylic acids, and their mixtures.

Abstract: A corrugated fuel tube is manufactured by extruding an inner single layer or multilayer of a resin of high fuel impermeability, extruding an outer single layer or multilayer of a thermoplastic resin so as to cover the inner layer to form a tube having a multi-layered wall, and corrugating the tube along at least a part thereof. The surface treatment is preferably given to an outer peripheral surface of the inner layer to ensure an improved adhesion between the inner and outer layers. The tube can be made without presenting any problem caused by a difference in melt viscosity between the materials forming its inner and outer layers.

Abstract: A producing method of a hose including, using a mold assembly constituted by a pair of semicylindrical molds each having a large number of intrusion grooves formed along the axial direction in the cylindrical surface of each of the semicylindrical molds substantially at regular intervals and supplying electrically conductive wire into the hose molding mold assembly substantially linearly along the axial direction of the mold assembly; extruding a molten resin tubularly to supply the molten resin into the mold assembly after the supply of the electrically conductive wire; supplying high-pressure air into the inside of the thus extruded molten resin tube to thereby expand the molten resin tube along the corrugated surface of the mold assembly to bring the molten resin tube into contact with the corrugated surface of the mold assembly and, at the same time, making a part of the tube go around to the outer circumferential surface side of the electrically conductive wire along the intrusion grooves of the mold ass

Abstract: A process for making a length of rubber tubing with axially spaced circumferentially corrugated flexible segments from a sleeve of uncured rubber and the product resulting therefrom. An end length of a sleeve of uncured rubber is placed over an end portion of a forming mandrel and an external form is placed around the sleeve end length. Rudimentary corrugations are then formed in the end length after which the sleeve is moved axially along the forming mandrel so that a new length portion of the sleeve is placed in a forming position. Then using the external form, rudimentary corrugations are formed in the second length portion of the sleeve. These steps are repeated until the desired number of axial length portions in the sleeve are provided with rudimentary corrugations. The resulting product is then cured to form a length of rubber tubing with a plurality of axially spaced circumferentially corrugated flexible segments.

Abstract: A method of forming a plastic product comprises extruding molten plastic into a mold having a mold wall with product shaping interior face. After shaping the product in the mold, the method includes introducing gas via a gas inlet through the mold wall onto the product to cool both the product and the mold and then discharging the gas from the mold at a location remote from the gas inlet.

Abstract: The invention relates to a method for manufacturing a multi-layer corrugated pipe and to a corrugated pipe manufactured by the method and comprising an inner tube (2), a corrugated outer tube (5) and a plastic layer therebetween. Separate layers (3,6) of plastic are formed on the outer surface of the inner tube (2) and the inner surface of the outer tube (5), said separate layers of plastic being affixed to one another at least at the web portions (5a) of the corrugations of the outer tube (5) when the inner tube and outer tube are connected.

Abstract: Convoluted tubing of thermoplastic resin is made by extruding the resin as a molten tubular extrudate, feeding said extrudate into the interior of a rotating tubular member which has a helical thread in the interior of said member, the spiral thread having a deformation zone receiving the extrudate and a cooling zone downstream from the deformation zone. A vacuum can be used to force the extrudate against the spiral thread in the deformation zone to spirally convolute the extrudate. The rotation of the tubular member causes the resultant convoluted tubing to engage the spiral thread in the cooling zone for conveyance through such zone. Apparatus comprising the rotating tubular member with the interior thread for forming the convoluted tubing is provided.

Abstract: A plastic part forming apparatus includes a mold tunnel into which molten plastic is fed to form the plastic part. The mold tunnel is made from thermally conductive material and has a part shaping interior face which is non-reflective such that the interior surface has high capacity to absorb heat energy from the plastic fed into the mold tunnel. The thermally conductive material then dissipates the heat energy from the mold tunnel.

Abstract: A method of forming a two-layer plastic pipe (4;8) to be laid in the ground for conducting material therethrough forms a core pipe (2) consisting essentially of a first plastic material and forms a detachable outer hose (3;7) of a second plastic material around said core pipe (2) by a suitable coating method, including in said second plastic material an amount of additives effective to protect said core pipe with said outer hose from stresses and loads of laying said core pipe and outer hose and usage thereof in ground.

Abstract: An apparatus for forming a thermoplastic pipe having a profiled surface includes a nozzle having an extrusion orifice feeding extrudate in a downstream direction to a mold path which extends from the nozzle and along which are provided a first mold block and a second mold block downstream of the first mold block. The mold blocks are closable around the extrudate to form the pipe and are openable to release the pipe. The mold blocks are moved together with one another and with the pipe in the downstream direction when the mold blocks are closed and are opened and sequentially moved in an upstream direction along an axis contiguous with the axis of the mold path while the extrudate continues to move in the downstream direction. The first mold block is moved in the upstream direction before the second mold block such that the mold blocks never pass one another on the mold path.

Abstract: An apparatus for the manufacture of pipes of thermoplastic plastics having transverse profile features comprises mold segment halves guided by twos to circulate on a molding path. A conveying device is provided for the recirculation of the mold segment halves, working in the way of a gantry crane. On a conveying bridge overlapping the molding path, two conveying carriages are provided, which are displaceable in directions opposite to each other and at right angles to the direction of production and to each of which is attached a conveying arm directed downwards and having a holding device for a mold segment half.