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GB858616A - Production of seamless thermoplastic tubing - Google Patents

Production of seamless thermoplastic tubing

Info

Publication number
GB858616A
GB858616A GB296/59A GB29659A GB858616A GB 858616 A GB858616 A GB 858616A GB 296/59 A GB296/59 A GB 296/59A GB 29659 A GB29659 A GB 29659A GB 858616 A GB858616 A GB 858616A
Authority
GB
United Kingdom
Prior art keywords
tubing
point
extrusion
tube
gaseous medium
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
GB296/59A
Inventor
Gerald Benjamin Dyer
Warner Paul Heinstein
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
DuPont Canada Inc
Original Assignee
DuPont Canada Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to US757635A priority Critical patent/US2966700A/en
Priority claimed from US757635A external-priority patent/US2966700A/en
Application filed by DuPont Canada Inc filed Critical DuPont Canada Inc
Priority to GB296/59A priority patent/GB858616A/en
Priority to FR784620A priority patent/FR1226472A/en
Priority to DEP22141A priority patent/DE1211379B/en
Publication of GB858616A publication Critical patent/GB858616A/en
Expired legal-status Critical Current

Links

Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/908—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article characterised by calibrator surface, e.g. structure or holes for lubrication, cooling or venting
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/09—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels
    • B29C48/10—Articles with cross-sections having partially or fully enclosed cavities, e.g. pipes or channels flexible, e.g. blown foils
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/89—Internal treatment, e.g. by applying an internal cooling fluid stream
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/90—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article
    • B29C48/901—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies
    • B29C48/902—Thermal treatment of the stream of extruded material, e.g. cooling with calibration or sizing, i.e. combined with fixing or setting of the final dimensions of the extruded article of hollow bodies internally
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/88—Thermal treatment of the stream of extruded material, e.g. cooling
    • B29C48/911—Cooling
    • B29C48/9115—Cooling of hollow articles
    • B29C48/912—Cooling of hollow articles of tubular films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0018—Combinations of extrusion moulding with other shaping operations combined with shaping by orienting, stretching or shrinking, e.g. film blowing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/001—Combinations of extrusion moulding with other shaping operations
    • B29C48/0019—Combinations of extrusion moulding with other shaping operations combined with shaping by flattening, folding or bending

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Physics & Mathematics (AREA)
  • Thermal Sciences (AREA)
  • Shaping By String And By Release Of Stress In Plastics And The Like (AREA)
  • Extrusion Moulding Of Plastics Or The Like (AREA)

Abstract

<PICT:0858616/IV(a)/1> <PICT:0858616/IV(a)/2> <PICT:0858616/IV(a)/3> <PICT:0858616/IV(a)/4> <PICT:0858616/IV(a)/5> Seamless tubing is made by continuously dry-extruding molten thermoplastic material in tubular form, flattening the tubing at a point spaced from the point of extrusion, maintaining a substantially constant continuous bubble of a gaseous medium in the section of tubing extending from the point of extrusion to the point of flattening, the gaseous medium in the bubble being under a differential pressure such that the pressure in the zone nearest the point of extrusion is sufficient to expand the tubing while in the plastic formative state to the desired diameter at a point beyond the point of extrusion, while the pressure in the zone beyond the point of expansion to the desired diameter is sufficient to keep the tubing expanded but insufficient to cause further expansion, and cooling the tubing between the point of extrusion and the point of expansion to the final desired diameter, the rate of withdrawing the tubing, the degree of expansion of the tubing and the degree of cooling the tubing all being correlated in accordance with predetermined desired physical characteristics of the tubing. The thermoplastic material may be polyethylene, polypropylene, a polyester, a polyamide, a polyvinyl halide, a polyvinylidene halide, or a copolymer of a vinyl or vinylidene halide with another polymerizable organic compound. The bubble of gaseous medium may be isolated or may be open to the atmosphere at a point before the point of extrusion. A controlled volume of cooling medium may be directed on to and around the exterior of the tubing, and the interior of the tubing may be cooled by means of a continuously circulating liquid cooling medium not in direct contact with the tubing. Apparatus as shown comprises in each case an annular extrusion die 1, means for extruding a molten thermoplastic material through the lips of the die 2 in the form of seamless tubing 9, means 3, 6 for admitting a gaseous medium into said tubing and means 4, 5 for causing a back pressure in said tubing in the vicinity of the point of extrusion to cause expansion of the tubing to a predetermined diameter, said means for causing a back pressure may comprise (Fig. 2) a circular plate 5 attached to the die at a point beyond the point of extrusion, the plate having an opening therein within which is positioned a fan 12 designed to blow the gaseous medium in the direction of the die face and countercurrent to the flow of gaseous medium at the point of emission thereof into the tubing. Alternatively, the means for admitting the gaseous medium into the tubing may comprise a tube (3) inserted through the centre of the die in which tube is positioned a second tube 4 of smaller diameter, the second tube being attached at a point beyond the point of extrusion to a concentric circular plate 5 (Fig. 3). Alternatively (Figs. 5 and 6) the back pressure causing means may comprise a shaped cooler 5 attached to the die and provided with inlet and outlet means 14, 15 for circulating a liquid cooling medium through the interior of the shaped cooler. The shaped cooler may have an opening through its central portion (Fig. 6) within which is positioned a fan (not shown, but as in Fig. 2) designed to blow the gaseous medium in the direction of the die face and countercurrent to the flow of gaseous medium at the point of its emission into the tubing Alternatively (Fig. 5) the means for admitting gaseous medium into the tubing may comprise a tube 3 inserted through the centre of the die and adjacent to the lower portion of the shaped cooler in which tube is positioned a second tube 4 of smaller diameter, the second tube being attached at a point beyond the point of extrusion to that part of the shaped cooler furthest from the point of extrusion of the thermoplastic material. In operation, inflating air entering zone P1 emerges in the tubing 9 before the plate or shaped cooler 5 and builds up a back pressure in this zone until tubing 9 expands enough to create a gap between the tubing and the plate or cooler. Air then escapes to zone P2, keeping the tubing from touching the plate or cooler, and this air, in the apparatus of Figs. 1, 3 and 5, is bled off to atmosphere via tube 4, a valve or hydrostatic leg of liquid being positioned at point 8 to control the pressure in zone P2 so that it is just sufficient to keep the tubing 9 inflated to the proper diameter but insufficient to cause further expansion. In contrast to this "open-bubble" system, Figs. 2 and 6 illustrate a closed or "isolated-bubble" system in which inflating air is admitted through tube 3 to expand tubing 9 to the desired diameter and the valve 11 (not shown in Fig. 6) is then closed.
GB296/59A 1958-08-27 1959-01-03 Production of seamless thermoplastic tubing Expired GB858616A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US757635A US2966700A (en) 1958-08-27 1958-08-27 Production of thermoplastic seamless tubing
GB296/59A GB858616A (en) 1958-08-27 1959-01-03 Production of seamless thermoplastic tubing
FR784620A FR1226472A (en) 1958-08-27 1959-01-21 Improvements in the production of seamless plastic tubes
DEP22141A DE1211379B (en) 1958-08-27 1959-01-30 Method and device for producing blown films from thermoplastics

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US757635A US2966700A (en) 1958-08-27 1958-08-27 Production of thermoplastic seamless tubing
GB296/59A GB858616A (en) 1958-08-27 1959-01-03 Production of seamless thermoplastic tubing
FR784620A FR1226472A (en) 1958-08-27 1959-01-21 Improvements in the production of seamless plastic tubes

Publications (1)

Publication Number Publication Date
GB858616A true GB858616A (en) 1961-01-11

Family

ID=27245216

Family Applications (1)

Application Number Title Priority Date Filing Date
GB296/59A Expired GB858616A (en) 1958-08-27 1959-01-03 Production of seamless thermoplastic tubing

Country Status (2)

Country Link
FR (1) FR1226472A (en)
GB (1) GB858616A (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4983754A (en) * 1972-12-16 1974-08-12
JPS5382864A (en) * 1976-12-27 1978-07-21 Union Carbide Corp Film making method and apparatus

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1050082A (en) * 1962-05-08 1900-01-01
FR2341421A1 (en) * 1976-02-23 1977-09-16 Exxon Research Engineering Co PROCESS FOR THE PRODUCTION OF A TUBULAR FILM IN FILM-GENERATING THERMOPLASTIC MATERIAL

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS4983754A (en) * 1972-12-16 1974-08-12
JPS5382864A (en) * 1976-12-27 1978-07-21 Union Carbide Corp Film making method and apparatus

Also Published As

Publication number Publication date
FR1226472A (en) 1960-07-13

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