EP0096957A2
Expired / Lapsed
EP
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Apparatus for producing multi-walled thermoplastic tubing
Assignee: Individual
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Filing: 1983-04-19
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Granted: —
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Expires: 2003-04-19
Abstract
Abstract In an apparatus for producing multi-walled thermoplastic tubing in which the inner and outer tubing walls (33 and 26 respectively) are continuously formed by extrusion one within the other, the inner tube (33) being urged outwardly into pressing engagement with the outer tube (26), the mechanism for urging the inner tube outwardly into securement with the outer tube comprises a mandrel (70) mounted coaxially with the die (25) for extruding the inner tube and on the downstream side of it. The mandrel has an outer surface providing a tapered end portion (72) positioned to receive the inner tube as it is extruded, and a generally cylindrical portion (71) positoned to urge the inner tube into securement with the outer tube. To prevent sticking of the thermoplastic material to the mandrel, the outer surface of the mandrel is maintained at a temperature lower than the molding temperature and is transversely ribbed (73).
Inventors
- 👤 Manfred Arno Alfred Lupke
- 👤 Gerd Paul Heinrich Lupke
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-07 04:58
CPC Classifications
B; B29; B29C; B29C49/00; B29C49/42; B29C49/48; B29C49/4823; B29C48/00; B29C48/001; B29C48/0013; B29C48/0015; B29C48/0016; B29C48/03; B29C48/09; B29C48/11; B29C48/13; B29C48/16; B29C48/18; B29C48/21; B29C48/25; B29C48/30; B29C48/3001; B29C48/3003; B29C48/303; B29C48/32; B29C48/335; B29C48/88; B29C48/911; B29C48/9115; B29C35/00; B29C35/16; B29C2035/1616; B29C2035/1658; B29C2791/00; B29C2791/004; B29C2791/006; B29C48/0017; B29C48/90; B29C48/904; B29C49/42407; B29C49/42408; B29L; B29L2016/00; B29L2023/00; B29L2023/18; B29L2023/186; B29L2024/00; B29L2024/003; Y; Y10; Y10T; Y10T156/00; Y10T156/10; Y10T156/1002; Y10T156/1007; Y10T156/1016
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
125 words
In an apparatus for producing multi-walled thermoplastic tubing, the apparatus including an annular extrusion die for extruding an inner tube of thermoplastic material coaxially within an outer tube as the latter is advanced in an axial direction, and a mandrel mounted coaxially with said die, downstream thereof for urging the inner tube outwardly into securement with the inner surface of the outer tube, the mandrel having an outer surface positioned to receive the Inner tube of thermoplastic from the die and to support the inner tube in pressing relation with the outer tube, characterized by: transverse ribs (73,80) on the outer surface of the mandrel (70) and means (74,75; 78,79) for maintaining said outer surface of the mandrel at a lower temperature than the die.
Claim 2
Dependent Claim
125 words
In an apparatus for producing multi-walled thermoplastic tubing, the apparatus including an annular extrusion die for extruding an inner tube of thermoplastic material coaxially within an outer tube as the latter is advanced in an axial direction, and a mandrel mounted coaxially with said die, downstream thereof for urging the inner tube outwardly into securement with the inner surface of the outer tube, the mandrel having an outer surface positioned to receive the Inner tube of thermoplastic from the die and to support the inner tube in pressing relation with the outer tube, characterized by: transverse ribs (73,80) on the outer surface of the mandrel (70) and means (74,75; 78,79) for maintaining said outer surface of the mandrel at a lower temperature than the die.
Claim 3
Dependent Claim
60 words
Apparatus according to claim 1, including first and second annular extrusion dies (24,25) for forming said outer and inner tubes, the dies being mounted coaxially with one another on a cylindrical support (28) extending in said axial direction and characterized in that the mandrel is mounted on the cylindrical support (28) in spaced relation to the second annular die (25).
Claim 4
Dependent Claim
59 words
Apparatus according to claim 2, characterized in that the cylindrical support (28) constitutes a supply duct for pressurized gas, the support providing ports (30) downstream of the first annular die (24-) for admitting pressurized gas to the interior of the first tube of thermoplastic material thereby to expand said first tube in molding relation with a cooperating cavity (21).
Claim 5
Dependent Claim
19 words
Apparatus according to claim 1, 2 or 3, characterized in that the mandrel is formed of thermally nonconductive material.
Claim 6
Dependent Claim
47 words
Apparatus according to claim 1, 2 or 3, characterized by a coolant coil (73) embedded in the mandrel adjacent the outer surface thereof, and means (74,75) for flowing coolant through the coil, the turns of the coil projecting from the surface and providing the transverse ribs thereof.
Claim 7
Dependent Claim
36 words
Apparatus according to claim 1, 2 or 3, characterized in that the mandrel is formed of thermally conductive material and with internal coolant passages (78) and the apparatus provides means (79) for.flowing coolant through said passages.
Claim 8
Dependent Claim
52 words
Apparatus according to claim 1, 2 or 3, characterized in that the outer surface of the mandrel includes a generally cylindrical surface portion (71) and a tapered end portion, (72) the tapered end portion being positioned to receive the second tube and to guide the second tube to the cylindrical surface portion.
References Cited (Backward Citations)
No citation records indexed.
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