Device for the molding of corrugated pipe from extruded thermoplastic materials
OwnerAndrea Giuliano Vellaniinventor
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Abstract
The present invention relates to a device for shaping and cooling a smooth thin wall pipe, obtained from extrusion of a thermoplastic material, into a corrugated pipe shape. The most common technology to produce plastic corrugated pipe uses a series of split molds carried by two continuous chains, the split molds locking around an extruded smooth pipe which by means of a slight positive pressure is forced against the inside walls of the molds (which travel at extrusion speed) therefore shaping the hot plastic pipe into a corrugated shape. At the same time excessive heat is dissipated by a forced flow of air passing over the outside surface of the molds. This system requires a great number of molds and therefore machines of great encumberance.
Claims4
A device for the molding of corrugated pipe from extruded thermoplastic materials comprising:
- a stationary frame having a first end mounted adjacent to the exit of an extruding machine and a second end downstream from said first end;
- a rotatable mold in said stationary frame having a first end adjacent to and aligned with said first end of said stationary frame, and a second end downstream of said first end through which a corrugated pipe exits;
- means mounting said mold for rotatable movement in said stationary frame;
- means for rotatably driving said mold about its longitudinal axis, said mold comprising a central passage forming an inner wall of said mold, said inner wall having a spiral groove formed along the length thereof, said stationary frame having means for cooling said mold and the extrudate, and means for supplying air pressure to the interior of the extrudate when passing through said central passage, said means for supplying air pressure comprising a source of pressurized air, and passage means connecting said source of pressurized air to the interior of said central passage, wherein said means for supplying pressurized air further comprises a mandrel mounted in said central passage having a first plug mounted at one end thereof, and a second plug mounted at the other end thereof, said first plug positioned within said first end of said stationary frame, and said second plug spaced downstream from said first plug and positioned within said central passage, said mandrel having a passageway in the center thereof forming part of said passage means of said means for supplying air pressure, whereby when pressurized air is directed to the interior of said central passage the extrudate is forced outwardly into contact with said spiral groove of said inner wall, wherein each of said first end and said second end of said stationary frame has an opening formed therein for the passage of extrudate therethrough each opening having a seal therearound for preventing the flow of air therethrough.
Dependencies are inferred from the claim text.