Plastic and nonmetallic article shaping or treating: processes – Forming continuous or indefinite length work – Of varying cross-sectional area or with intermittent...
Patent
1978-11-13
1980-08-19
Silbaugh, Jan H.
Plastic and nonmetallic article shaping or treating: processes
Forming continuous or indefinite length work
Of varying cross-sectional area or with intermittent...
264541, 425532, 425381, 425465, 425466, D01D 520
Patent
active
042184169
ABSTRACT:
The method and apparatus are useful in forming a parison which has a varying wall thickness and an outer diameter larger than the outer diameter of the annular outlet orifice from which the parison is extruded. Such a parison is obtained by adding additional molten thermoplastic material to the parison while extruding the same to vary the thickness of portions of the parison. The additional molten material is directed radially outwardly from the axis of the parison to increase the wall thickness and to increase the swell of the parison which is defined as the ratio of the inner diameter of the parison to the outer diameter of the outlet orifice. Also the ratio of the outer diameter of the parison to the inner diameter of a mold in which the parison is blowmolded into a container is reduced permitting a larger container to be formed from the thicker portion of the parison while having a small entrance opening formed from a thin wall portion of the parison. The apparatus includes an extrusion head for extruding the parison from a circular outlet opening in the bottom of the head which is coaxial with a plunger received in a central passageway in the extrusion head. The plunger can be lowered to allow additional molten material to flow from the central passageway and through an annular orifice defined between the lower end of the plunger and the circular outlet opening. This lower end has an annular frustoconical surface for directing the additional molten thermoplastic material being added to the parison radially outwardly from the axis of the parison to obtain the increased swell and increased wall thickness of the parison.
REFERENCES:
patent: 3078507 (1963-02-01), Park
patent: 3176494 (1965-04-01), Cullen et al.
patent: 3312766 (1967-04-01), Stevens
patent: 3420926 (1969-01-01), Mason et al.
Baxter Travenol Laboratories Inc.
Collins H. W.
Flattery Paul
Silbaugh Jan H.
Vigil Thomas
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