초록 ▼

An edge forming tool is pressed into a thermoplastic sheet which is supported on an anvil or counter tool. The edge forming tool is maintained at a temperature below the melting temperature of the thermoplastic sheet and a high frequency electric field is established between the edge forming tool an

An edge forming tool is pressed into a thermoplastic sheet which is supported on an anvil or counter tool. The edge forming tool is maintained at a temperature below the melting temperature of the thermoplastic sheet and a high frequency electric field is established between the edge forming tool and the counter tool. The high frequency electric field softens the thermoplastic sheet which is deformed by the edge forming tool. Thereafter, the softened and deformed portions of the thermoplastic sheet are allowed to cool and re-harden before the sheet is folded to form a bend therein.

대표청구항 ▼

An apparatus for the production of container blanks by forming flexible fold lines in a thermoplastic sheet comprising a rule-shaped forming tool and a substantially flat surface for supporting said sheet, means for cooling said tool, means for moving said tool toward said substantially flat surface

An apparatus for the production of container blanks by forming flexible fold lines in a thermoplastic sheet comprising a rule-shaped forming tool and a substantially flat surface for supporting said sheet, means for cooling said tool, means for moving said tool toward said substantially flat surface, means for electrically insulating said cooling means from said moving means, and means for creating a high frequency electric field between said tool and said substantially flat surface whereby the temperature applied to the surface of said sheet adjacent said tool is less than the temperature applied in the middle of said sheet in an area adjacent said tool.