Parison engaging, severing and stripping mechanism

Claim 2

In a blow mold for use in a free-extrusion blow molding machine wherein a tubular parison is enclosed and blown to a final shape in a mold cavity defined interiorly of said mold, the mold having a pair of mold sections actuated for opening and clOsing movement, the sections when closed defining the mold cavity and pinching shut axially spaced portions of said tubular parison, the improvements of an opposed pair of parison-engaging elements slidably and resiliently mounted on the respective mold sections exteriorly of said mold cavity, said elements each normally resiliently projecting beyond the confines of its respective section to initially engage and pinch the tubular parison before full closure of the mold sections upon the parison during closing movement thereof, said elements remaining in contact with the tubular parison during blowing and during a substantial part of the opening movement of the mold sections, and a parison-severing knife fixed to one of said sections, said knife also projecting beyond the confines of the one section but less than the projection of the corresponding element to engage and sever the element-pinched portion of the parison during and under the impetus of closing movement of the mold sections.

Claim 3

In a blow mold as defined in claim 1, the further improvements wherein said parison-engaging elements on each mold section each includes a pair of axially spaced parison-engaging faces, and said parison-severing knife is interposed intermediate the parison engaging faces of said elements.

Claim 4

In a blow mold as defined in claim 1, and wherein the mold sections are moved arcuately to and from their closed cavity-defining positions, the further improvements wherein said slidable parison-engaging elements move arcuately relative to said mold sections.

Claim 5

In a blow molding system having a plurality of aligned and reciprocating sets of separable blow mold halves which open and close by substantially horizontal relative movement and which are arranged beneath an extruder, and wherein the upper set is closed for blowing while the lower set is simultaneously opening following blowing, the improved mold construction comprising: a parison-gripping element slidably and resiliently mounted on each of the mold halves at a point below the respective mold cavity, each of said gripping elements being positioned and dimensioned to normally resiliently project beyond the confines of its respective mold half and towards the mating mold half so that, during closing of the mating mold halves, the pair of opposed gripping elements of said mold pair will initially engage and pinch together the tubular parison prior to full closing of said mold pari, and said gripping faces continuing to grip the parison during a substantial part of the opening movement of the mold halves; a parison-severing knife mounted on one mold half of each pair at a point laterally aligned with the pinched portion of the parison so that portions of the gripping elements on such mold half pair are positioned both above and below the knife to maintain gripping support of the severed tubular parison on both sides of the severing line following severing and as the mold halves open; and knife actuating means for causing said knife to engage and severe the parison after pinching and prior to the opening of the mold halves.

Claim 6

In a blow molding system having a plurality of aligned and reciprocating sets of separable blow mold halves which open and close by substantially horizontal relative movement and which are arranged beneath an extruder, and wherein the upper set is closed for blowing while the lower set is simultaneously opening following blowing, the improved mold construction comprising: a parison-gripping element slidably and resiliently mounted on each of the mold halves at a point below the respective mold cavity, each of said gripping elements being positioned and dimensioned to normally resiliently project beyond the confines of its respective mold half and towards the mating mold half so that, during closing of the mating mold halves, the pair of opposed gripping elements of said mold pair will initially engage and pinch together the tubular parison prior to full closing of said mold pari, and said gripping faces continuing to grip the parison during a substantial part of the opening movement of the mold halves; a parison-severing knife mounted on one mold half of each pair at a point laterally aligned with the pinched portion of the parison so that portions of the gripping elements on such mold half pair are positioned both above and below the knife to maintain gripping support of the severed tubular parison on both sides of the severing line following severing and as the mold halves open; and knife actuating means for causing said knife to engage and severe the parison after pinching and prior to the opening of the mold halves.