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 device for manufacturing a double-walled thermoplastic pipe with a connecting sleeve has a molding tunnel with a succession of molds for forming a corrugated molding wall and a connecting sleeve, respectively. An extrusion device extrudes a first flexible tube into said molding tunnel and a second flexible tube into said first flexible tube. A first gas channel is arranged for generating a pressure between said first and second flexible tubes. A compressed-gas control device is connected to said first gas channel for generating a pressure p1 or a pressure p2 in said space between said first and second flexible tubes by compressed air emerging from said first gas channel. A second compressed-gas control device is connected to a second gas channel for guiding compressed gas onto an inner side of said second flexible tube. Said first pressure controller is connected to said first gas channel via a compressed-gas line that is connected to an additional compressed-gas reservoir for gas exchange therewith.

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.

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 device for cutting slits in plastic tubes produces a plurality of cuts spaced around tubing passed through the device. The device comprises a plurality of rotatable members (3) located at different circumferential positions around a tube passage (2) through the device. Each rotatable member is provided with a tube cutter (25) which is directed at and away from the tube passage (2) with rotation of each member (3). These rotatable members (3) are adjustable radially of the tube passage (2) for accommodating diametric variances in the tubing.

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 device for manufacturing a double-walled thermoplastic pipe with a connecting sleeve has a molding tunnel with a succession of molds for forming a corrugated molding wall and a connecting sleeve, respectively. An extrusion device extrudes a first flexible tube into said molding tunnel and a second flexible tube into said first flexible tube. A first gas channel is arranged for generating a pressure between said first and second flexible tubes. A compressed-gas control device is connected to said first gas channel for generating a pressure p1 or a pressure p2 in said space between said first and second flexible tubes by compressed air emerging from said first gas channel. A second compressed-gas control device is connected to a second gas channel for guiding compressed gas onto an inner side of said second flexible tube. Said first pressure controller is connected to said first gas channel via a compressed-gas line that is connected to an additional compressed-gas reservoir for gas exchange therewith.

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: 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.

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 ribbed pipe molding apparatus has a die with a plastic flow passage which carries molten plastic from an extruder to a mold for making the ribbed pipe. The plastic flow passage has a downstream flow region which exits at an acute angle through the external surface of the die. The inner wall of the end region which locates downstream of the outer wall of the flow passage in the downstream flow region of the passage has a transition wall part which is also inclined relative to the exterior surface of the die but which is sloped at a angle less than the main part of the downstream flow region of the passage. The transition wall part of the inner wall shapes the mouth of the passage so as to produce a wedging of the plastic flowing through the passage into the mold for extremely efficient production of the ribs on the pipe.

Abstract: A molding apparatus for molding plastic material with a profiled outer pipe wall has a mold tunnel in which plastic material is shaped to form the pipe. The mold tunnel includes a first plastic cooler against which the plastic material flows for contact cooling of the plastic material. The mold tunnel further includes a second plastic cooler downstream of the first plastic cooler. The second plastic cooler provides an air cooling of the plastic material which surrounds the second plastic cooler in the mold tunnel.

Abstract: A ribbed pipe molding apparatus has a die with a plastic flow passage which carries molten plastic from an extruder to a mold for making the ribbed pipe. The plastic flow passage has a downstream flow region which exits at an acute angle through the external surface of the die. The inner wall of the end region which locates downstream of the outer wall of the flow passage in the downstream flow region of the passage has a transition wall part which is also inclined relative to the exterior surface of the die but which is sloped at a angle less than the main part of the downstream flow region of the passage. The transition wall part of the inner wall shapes the mouth of the passage so as to produce a wedging of the plastic flowing through the passage into the mold for extremely efficient production of the ribs on the pipe.

Abstract: A molding apparatus which is used in a continuous molding operation includes an endless looped track, track carriers which are moved around the track to and from a product shaping mold region and a transfer system for replacement of mold block members used in the apparatus. The transfer system, which operates without interrupting the molding operation includes transfer carriers controlled to move synchronized with the track carriers at a transfer location remote from the mold region and actuators which slide the mold block members between the track carriers and the transfer carriers at the transfer location when the transfer carriers are synchronized with the track carriers.

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: In a pipe made from a plurality of pipe sections, at least one of those sections has a curved configuration and each pipe section has opposite side flanges which are sealed with one another to hold the pipe sections together in forming the pipe.

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.