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: Die tooling is formed by forming a series of passages extending in the length of the tooling where each passage has a circumference defined within a body member of the tooling. Preferably the passages are primarily formed using a drilling procedure. The passages define a predetermined pattern of outlets adjacent the extrusion outlet or outlets. The passages between the inlets and outlets can be formed in a series of connected body members with each passage extending through each body member. Die tooling of this design is more robust and cost effective to manufacture.

Abstract: A molding apparatus for the manufacture of pipe advantageously uses a cooling plug that is adjustably-secured to the extrusion head to compensate for misalignment of the extrusion head relative to recirculating mold blocks. This provides a simplified adjustment for adjusting the molding apparatus to correct for wall thickness variations in the molded pipe. This apparatus can be used in combination with existing alignment systems.

Abstract: The pipe molding system includes a separable cooling plug and an automatic procedure to alleviate problems associated with excess plastic continuing to extrude after a sudden shutdown of the extrusion system. The separable cooling plug and shutdown procedure includes accommodating any excess plastic in a created void between the cooling plug and the extruder. This arrangement simplifies removal of the excess plastic and reduces the time required to return the equipment to normal production. Preferably, a controller monitors operating conditions of the system and automatically releases the cooling plug based on the monitored operating conditions.

Abstract: A corrugated pipe having a non circular in cross section profile and at least one generally elongate wall section is improved by using a variable height corrugation in the length of the elongate wall segment. The variable height corrugation is of a greatest height at a center portion thereof and decreases in height towards the end points of the elongate wall segment. A spanning type truss arrangement is formed that opposes inward deflection of the straight wall segment.

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 pipe cutting apparatus includes a machine base having a first machine table slidably secured for moving with a pipe during the extrusion thereof. The apparatus includes a rotary base table with a cutting arrangement attached at a periphery thereof such that the cutting arrangement orbits about the pipe during cutting thereof. The cutting arrangement includes a cutting tool supported on a pivoting support arm. The support arm includes an independent powered gear drive train for pivoting the support arm to accommodate different sizes of pipe and to allow cutting. Preferably the cutting apparatus has a second slidable table to allow precision cutting of multiple cuts of the pipe while the pipe is clamped or held.

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: In a method for manufacturing a double-walled, thermoplastic tube with a connecting sleeve, which enables precise and complete molding of the connecting sleeve by simple means, it is provided that a) a first tube (1) is extruded into a mold tunnel (4) comprising at least one row of molds (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 press

Abstract: A corrugated double wall plastic pipe with a bell connector at one end of the pipe section and an insert connector at the opposite end of the pipe. The insert connector includes an inner wall that cooperates with the bell connector at the junction of the bell connector and the pipe to continue to the inner wall between pipes joined by an insert connector of one pipe inserted in the bell connector of a second pipe.

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 pipe mold (1) produces plastic pipe with an internal wall having a first wall portion (23, 25) and a second wall portion (27). The pipe mold (1) includes a two stage cooling plug (35) to assist in setting the pipe wall. The first cooling stage (37) is controlled to remove heat from the pipe wall to partially set the plastic without excessive cooling. The partially set plastic pipe then passes over a second stage (39) where less precision in the cooling of the pipe occurs. The partially set plastic is more tolerant and subject to less damage. Preferably both the first and second stages (37, 39) include separate temperature sensors (120, 122) and control arrangements (124, 126) for varying the cooling medium of each stage. In a preferred embodiment a cooling medium is circulated through a first stage at a temperature and at a flow rate to maintain the first stage (37) within a narrow temperature range about the temperature of the cooling medium.

Abstract: The pipe molding system includes a separable cooling plug and an automatic procedure to alleviate problems associated with excess plastic continuing to extrude after a sudden shutdown of the extrusion system. The separable cooling plug and shutdown procedure includes accommodating any excess plastic in a created void between the cooling plug and the extruder. This arrangement simplifies removal of the excess plastic and reduces the time required to return the equipment to normal production. Preferably, a controller monitors operating conditions of the system and automatically releases the cooling plug based on the monitored operating conditions.

Abstract: A pipe molding apparatus includes a plurality of mold blocks (9) which move along a molding path to form double wall plastic pipe having an outer pipe wall with corrugations which set outside diameter of the pipe and an inner wall around a bore through the pipe. The mold blocks (9) have profiled faces which determine shape of the pipe. The profiled faces are reconfigureable in profile between first depth of the corrugations and diameter of the bore through the pipe without varying external diameter and while maintaining essentially constant wall thickness of the pipe.

Abstract: A molding apparatus includes a moving mold for shaping molten plastic into product made within the moving mold. The moving mold is surrounded by an air block housing to define a cooling chamber exteriorly around the moving mold. At least one heat exchanger is located within the cooling chamber. The heat exchanger provides cooling air which is contained by the housing within the cooling chamber to act on and provide cooling of the moving mold.

Abstract: An extruding apparatus which extrudes continuous length of hollow plastic product has an extruder (3) which feeds molten plastic through die equipment (5) to a mold tunnel (7) formed by side by side moving mold blocks (9). The apparatus includes air turbulence internally of the product within the mold tunnel to assist in setting shape of the product. The air turbulence is provided by an air moving member (17) located internally of the product within the mold tunnel and a power source for the air moving member. The power source is located externally of the mold tunnel and a power transfer is provided to feed power from the power source through the die equipment to the air moving member without cooling of the die equipment.

Abstract: Equipment (1) used in the molding or plastic pipe includes die tooling (3) provided with a plastic flow distributor (25) at the upper end of the die tooling. The plastic flow distributor has adjustable flow to provide an even distribution of plastic from an extruder into at least one die passage (9) within the die tooling.

Abstract: A pipe mold (1) produces plastic pipe with an internal wall having a first wall portion (23, 25) and a second wall portion (27). The pipe mold (1) includes a two stage cooling plug (35) to assist in setting the pipe wall. The first cooling stage (37) is controlled to remove heat from the pipe wall to partially set the plastic without excessive cooling. The partially set plastic pipe then passes over a second stage (39) where less precision in the cooling of the pipe occurs. The partially set plastic is more tolerant and subject to less damage. Preferably both the first and second stages (37, 39) include separate temperature sensors (120, 122) and control arrangements (124, 126) for varying the cooling medium of each stage. In a preferred embodiment a cooling medium is circulated through a first stage at a temperature and at a flow rate to maintain the first stage (37) within a narrow temperature range about the temperature of the cooling medium.

Abstract: A molding apparatus includes a moving mold for shaping molten plastic into product made within the moving mold. The moving mold is surrounded by an air block housing to define a cooling chamber exteriorly around the moving mold. At least one heat exchanger is located within the cooling chamber. The heat exchanger provides cooling air which is contained by the housing within the cooling chamber to act on and provide cooling of the moving mold.

Abstract: Pipe molding apparatus having a moving mold tunnel includes an upstream and at least one downstream mold block. Each mold block 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 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 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 to compensate for the plastic shrinkage.