Claims
- 1. A method of continuously forming thin walled, foamed plastic containers by a blow molding method comprising the following steps:
- (a) introducing foamable plastic material to an extruder;
- (b) extruding said material through an orifice to form a tubular parison;
- (c) passing the parison into a molding apparatus which includes a plurality of mold sets moving on a continuous conveyor, each of said mold sets including two mold halves which when clamped together form two container molds adjacent to one another in closed-end to closed-end relationship, said mold sets abutting one another to form a series of cavities, each cavity in the shape of two containers abutting one another in mouth-to-mouth relationship;
- (d) closing adjacent mold sets in sequence such that any three adjacent mold sets form two complete molding cavities; and
- (e) pinching said parison with restriction members located substantially at the mid-point of each mold set, said restriction members having a small space therebetween;
- (f) blowing gas through a needle extending into the second of said three mold sets to said small space between said restriction members thereby expanding the parison to take on the contours of the two complete molding cavities and thereby forming two pairs of containers joined in mouth-to-mouth relationship;
- (g) further closing the restriction members to substantially eliminate said small space;
- (h) severing said containers without a cooling step by passing a cutting means through the plastic material joining said containers in mouth-to-mouth relationship while said mold sets are closed;
- (i) continuing to maintain gas in said containers during said severing step to hold the containers against the walls of the cavities to facilitate the passing of the cutting means to sever said material joining said containers; and
- (j) opening said molds sets to permit the containers to be removed therefrom.
- 2. The method according to claim 1 wherein a space is provided between said adjacent mold sets is of only sufficient width to permit the passage of a cutting knife.
- 3. The method according to claim 2 wherein said space permits the escape of said expanding gas along said knife edge to serve as a lubricant therefor.
- 4. A method for continuously forming thin walled, foamed plastic containers by blow molding method as recited in claim 1 further comprising:
- substantially continuously performing steps (a) through (j) such that said blowing step is repeated on every other one of said mold sets.
Parent Case Info
This application is a continuation of application Ser. No. 07/366,562, filed June 15, 1989, now abandoned.
US Referenced Citations (12)
Foreign Referenced Citations (2)
Number |
Date |
Country |
757782 |
Apr 1971 |
BEX |
38-11832 |
Jul 1963 |
JPX |
Continuations (1)
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Number |
Date |
Country |
Parent |
366562 |
Jun 1989 |
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