초록 ▼

An inwardly offset surface of the cover of a carton is cut in a plane transverse to the top of the cover. A protrusion on the bottom surface of a complementary recess in the latch flap extends through the hole to latch the carton with the protrusion being within the cover recess to prevent accidenta

An inwardly offset surface of the cover of a carton is cut in a plane transverse to the top of the cover. A protrusion on the bottom surface of a complementary recess in the latch flap extends through the hole to latch the carton with the protrusion being within the cover recess to prevent accidental opening of the carton. The mold for producing the carton cuts the hole while thermoforming by relative movement between a male key mounted in the male mold member and female key mounted in the female mold member. Both keys have flat surfaces transverse to the closing motion of the molds. These flat surfaces are biased into engagement one with the other so that the plastic is cut in a shearing action.

대표청구항 ▼

A process for the production of a thermoformed thermoplastic carton comprising: providing a relatively flat oriented sheet of polystyrene foam; preheating said sheet to at least its forming temperature; thermoforming said preheated sheet by bringing together a male mold member and a female mold memb

A process for the production of a thermoformed thermoplastic carton comprising: providing a relatively flat oriented sheet of polystyrene foam; 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 including a cover having a surface which is inwardly offset with respect to the front wall of said cover; shearing a hole in said surface while thermoforming by relative movement between a flat cutting surface of a male key mounted in said male mold member and a flat cutting surface of a female key mounted in said female mold member, said movement being parallel to the closing motion between said male and female members; biasing said flat cutting surface of said male key against said flat cutting surface of said female key to produce shearing of said sheet between said keys; and engaging an edge of said female cutting key with a beveled edge of said male cutting key to move said male key perpendicular to the closing motion between said male and female mold members whereby engagement between the flat surfaces of said male and female keys is obtained regardless of the alignment between said male and female mold members.