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US 4,487,731 AGranted
Process and apparatus for producing foamed synthetic resin bodies
AssigneeKanegafuchi Kagaku Kogyo Kabushiki Kaisha
InventorOsamu Kobayashi
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AssigneeKanegafuchi Kagaku Kogyo Kabushiki Kaisha
InventorOsamu Kobayashi
Estimating the term…
A process for producing a foamed synthetic resin body comprising continuously extruding a foamable thermoplastic resin extrudate composition from an extruder die into a reduced pressure zone, subjecting the extrudate to an expansion molding step, a cooling-hardening step and a cutting step while transporting the extrudate through the reduced pressure zone to obtain a foamed piece of predetermined length, shutting off a portion of the reduced pressure zone surrounding the foamed piece from the other portion thereof when the foamed piece has reached a specified position to restore the foamed piece surrounding portion to a normal pressure, subsequently discharging the foamed piece into the atmosphere, and thereafter bringing the surrounding portion into communication with the reduced pressure zone again upon reducing the pressure. Foamed resin bodies of desired expansion ratio and shape can be prepared continuously with high cooling efficiency. An apparatus for practicing the process is also disclosed. Such apparatus includes means to form a continuous length of extrudate within a vacuum chamber and means to cut the extrudate to length and means to pass the cut extrudate into a second chamber, and then to cause the cut length to exit the second chamber without affecting the reduced pressure in the chamber or reduced pressure zone.
A process for producing a foamed resin body comprising the steps of continuously extruding a foamable resin from an extruder into a reduced pressure zone, subjecting the extrudate to an expansion molding step, a cooling-hardening step, characterized by cutting the extrudate to obtain a foamed piece of predetermined length and separating the foamed piece of predetermined length from the preceding process steps when it has reached a specified position and restoring the foamed piece to a normal pressure, and subsequently discharging it to atmosphere.
A foam extrusion apparatus comprising a chamber at reduced pressure into which an extrudate is extruded to form a continuous length of foamed extrudate, characterized by means operative to cut the extrudate to length within said chamber, and means then to pass the cut length into a second chamber also at such reduced pressure, and means to cause the cut length to exit the second chamber without affecting the reduced pressure within the first mentioned chamber.
An extrusion apparatus for forming foamed boards, billets and the like comprising an extruder, a vacuum chamber, extrusion processing means within the vacuum chamber, and a bulkhead between the extruder and processing means closing and sealing an end of the vacuum chamber, and means to move said vacuum chamber toward and away from the bulkhead to open the chamber to provide access to said processing means.
A foam extrusion apparatus including a chamber at reduced pressure into which a foamable extrudate is extruded and in which it expands, characterized in that the extrudate is cut to length in said chamber and that a second contiguous chamber is provided which cyclically alternates between such reduced and atmospheric pressure, and means to transfer the cut length from the first mentioned chamber to the second chamber when the latter is in the reduced pressure portion of the cycle, and from the second chamber to atmosphere when the latter is in the atmosphere portion of the cycle.
Dependencies are inferred from the claim text.