Claims
- 1. A process for the production of a thermoformed thermoplastic carton comprising:
- providing a relatively flat oriented sheet of polystyrene foam having a sheet line;
- preheating said sheet to at least its forming temperature;
- thermoforming said preheated sheet by bringing together a male mold member and a female mold member to form said carton by:
- forming a cell section from said plastic sheet to define a plurality of cells extending from the sheet line in one direction;
- forming a dished cover resiliently hinged to the rear edge of said cell section, said cover being formed from said plastic sheet to define a front wall, a back wall, and end walls extending in said one direction from said sheet line and fixed to each other and to a top for said cover;
- stretching said plastic sheet in the opposite direction from said sheet line to form an extension from said cell section along the front edge of said cell section; and
- forming complementary latching elements on said cover front wall and on said extension from said cell section.
- 2. The method recited in claim 1 further comprising:
- forming a plurality of protrusions on said extension from said cell section.
- 3. The method recited in claim 1 further comprising:
- shearing a hole in said front cover while thermoforming, the latching elements on said extension being formed to extend through a complementary one of the holes of said cover to latch said carton in the closed position.
- 4. The thermoplastic carton thermoformed by the process recited in claim 1.
- 5. A mold for the production of a thermoformed thermoplastic carton comprising:
- a male mold member;
- a female mold member;
- means for closing said male and female mold members on a preheated flat sheet of polystyrene foam having a sheet line to produce a carton having a cover and a cell section from said sheet, said male mold member extending said cover and said cell section from said sheet line in one direction; and
- means in said mold members for stretching the front edge of said cell section in the opposite direction from said sheet line to form a cell section extension having mating elements of said latch thereon.
- 6. The mold recited in claim 5 further comprising:
- means in said male and female mold members for forming a hinge between said cover and said cell section, and wherein said means for stretching the front end of said cell section comprises:
- a former on said female mold member at the edge remote from, and parallel to, said means for forming a hinge, said former stretching the front edge of said cell section in said opposite direction upon closing.
Parent Case Info
This is a divisional of copending application Ser. No. 481,512, filed on Apr. 1, 1983 and now abandoned.
US Referenced Citations (5)
Divisions (1)
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Number |
Date |
Country |
Parent |
481512 |
Apr 1983 |
|