Abstract: Mold blocks of a pipe molding corrugator are provided with enhanced cooling capability due to the provision of cooling fins on the side portions of each mold block. Air can be forced between the fins and some exhaustion of the air can occur at the base of the fins adjacent the mold block cavity. With this arrangement, enhanced cooling of mold blocks is possible.

Abstract: Mold blocks of a pipe molding corrugator are provided with enhanced cooling capability due to the provision of cooling fins on the side portions of each mold block. Air can be forced between the fins and some exhaustion of the air can occur at the base of the fins adjacent the mold block cavity. With this arrangement, enhanced cooling of mold blocks is possible.

Abstract: A pipe connection used in corrugated pipe includes a male/female connection that is configured to accommodate movement of the male connector in the female connector after installation of the pipe. The ability to maintain a satisfactory pipe connection throughout a desired and designed range of movement is helpful in applications where the pipe may be exposed to changing conditions such as ground settling, ground shifting, earthquake or other conditions. The male connector and the female connector for receiving the male connector are oversized to allow additional insertion of the male connector or partial withdrawal of the male connector while maintaining the pipe connection throughout the range of movement. The pipe connection can also be used to provide an effective two stage male/female connection between reinforced plastic pipe sections.

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: The present invention provides a spider for a die head and die tooling that utilizes curved flow guides to direct the flow of plastic through the die head and die tooling. The spider leg splits the stream of plastic flowing through the spider into two independent streams at the upstream end. The downstream end comprises two curved flow guides that are configured to direct the two streams of plastic towards a longitudinal center plane of the spider leg. The turbulence caused by the curved flow guides creates obtuse or acute angled welding lines between the two streams of plastic. These obtuse and acute angled welding lines provide stronger bonds than the known spider legs that create butt welding or right angled welding lines.

Abstract: A pipe coupling for triple wall corrugated plastic pipe includes a triple wall corrugated bellmouth connector that is of a unitary construction with one end of the corrugated plastic pipe. This bellmouth connector is of higher strength and in cooperation with the two wall corrugated spigot provides a high strength coupling. This coupling includes the bellmouth connector and spigot that are made inline with the corrugated pipe. A method for the manufacture of the pipe includes controlling of an air pressure on the outside of a formed two wall corrugated pipe as an exterior third wall is secured thereto.

Abstract: The present invention provides a spider for a die head and die tooling that utilizes curved flow guides to direct the flow of plastic through the die head and die tooling. The spider leg splits the stream of plastic flowing through the spider into two independent streams at the upstream end. The downstream end comprises two curved flow guides that are configured to direct the two streams of plastic towards a longitudinal center plane of the spider leg. The turbulence caused by the curved flow guides creates obtuse or acute angled welding lines between the two streams of plastic. These obtuse and acute angled welding lines provide stronger bonds than the known spider legs that create butt welding or right angled welding lines.

Abstract: A pipe connection used in corrugated pipe includes a male/female connection that is configured to accommodate movement of the male connector in the female connector after installation of the pipe. The ability to maintain a satisfactory pipe connection throughout a desired and designed range of movement is helpful in applications where the pipe may be exposed to changing conditions such as ground settling, ground shifting, earthquake or other conditions. The male connector and the female connector for receiving the male connector are oversized to allow additional insertion of the male connector or partial withdrawal of the male connector while maintaining the pipe connection throughout the range of movement. The pipe connection can also be used to provide an effective two stage male/female connection between reinforced plastic pipe sections.

Abstract: A pulsating corrugator is provided with at least one secondary mold block that is selectively used for forming a spigot connection as the corrugated or ribbed pipe is formed. Preferably, the primary mold blocks used to form the corrugated pipe are also used to assist in further cooling of the formed spigot connection once released from the secondary mold block. The corrugator also includes a controller used to provide different air pressure as the mold blocks move past extrusion outlets of an associate extruder.

Abstract: 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.

Abstract: A two stage mold block transfer station is used the exit of a moving mold tunnel to quickly move mold blocks to a clear position relative to the molded product. Once in the clear position the mold block is rotated and provided to a return drive moving the mold block back to the inlet of the moving mold tunnel. By moving the last mold block of the moving mold tunnel primarily away from the longitudinal axis of the mold tunnel less mold blocks are required. Various arrangements for moving of the mold blocks can be used achieve this advantage.

Abstract: A pipe coupling for triple wall corrugated plastic pipe includes a triple wall corrugated bellmouth connector that is of a unitary construction with one end of the corrugated plastic pipe. This bellmouth connector is of higher strength and in cooperation with the two wall corrugated spigot provides a high strength coupling. This coupling includes the bellmouth connector and spigot that are made inline with the corrugated pipe. A method for the manufacture of the pipe includes controlling of an air pressure on the outside of a formed two wall corrugated pipe as an exterior third wall is secured thereto.

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 two stage mold block transfer station is used the exit of a moving mold tunnel to quickly move mold blocks to a clear position relative to the molded product. Once in the clear position the mold block is rotated and provided to a return drive moving the mold block back to the inlet of the moving mold tunnel. By moving the last mold block of the moving mold tunnel primarily away from the longitudinal axis of the mold tunnel less mold blocks are required. Various arrangements for moving of the mold blocks can be used achieve this advantage.

Abstract: 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.

Abstract: A pipe connection used in corrugated pipe includes a male/female connection that is configured to accommodate movement of the male connector in the female connector after installation of the pipe. The ability to maintain a satisfactory pipe connection throughout a desired and designed range of movement is helpful in applications where the pipe may be exposed to changing conditions such as ground settling, ground shifting, earthquake or other conditions. The male connector and the female connector for receiving the male connector are oversized to allow additional insertion of the male connector or partial withdrawal of the male connector while maintaining the pipe connection throughout the range of movement. The pipe connection can also he used to provide an effective two stage male/female connection between reinforced plastic pipe sections.

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 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 a powered gear drive train for pivoting the support arm to accommodate different sizes of pipe and to allow cutting. The cutting apparatus has a second slidable table to allow precision cutting of multiple cuts of the pipe while the pipe remains clamped or held. The clamp arrangement is supported on and movable with the second slidable table. A controlled actuator is used to move and determine the relative position of the slidable tables.

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: 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.