| 摘要 |
1,135,708. Seaming non-metallic sheet material. AKERLUND & RAUSING A.B. 13 Sept., 1967 [19 Sept., 1966], No. 41829/67. Headings B5D and B5K. A heat-sealed joint is formed between two sheets 1, 2 of material each having a heatsealable material 13 at least on one side thereof by positioning margins 9, 10 of the sheets 1, 2 with the heat-sealable materials 13 facing, but not contacting, each other to leave a narrow slot 11 therebetween, directing hot air through the slot 11 to heat the heat-sealable materials and pressing the margins 9, 10 together to form a tight joint. Preferably, the sheets 1, 2 each comprise a cardborad or paper layer 12 having an inner plastics coating 13. The sheets 1, 2 are clamped between a die 3 having a concave recess 17 and jaws 4 with their margins 9, 10 positioned to form the slot 11. Hot air is blown through the slot 11 from an orifice 8 provided in a recess 14 in the die 3. Passages (not shown), through which cooling water circulates may be provided in the die 3. After the coating 13 has been heated jaws 5, which had been slightly spaced apart, are pressed together. The jaws 5 are then moved apart and a jaw 7 having a concave recess 16 is advanced to press the material of the preliminary finlike joint into the recesses 16, 17 in the form shown in Fig. 3. The jaws 5 may be bevelled at 15. The invention is applicable to forming the corner joints of a carton, Fig. 4 (not shown), made from a blank having four side panels connected to, and adapted to fold up from, all sides of a bottom panel. The blank is positioned about a die which is provided with slot-like orifices to extend along the carton corners to direct hot air diagonally out of the corners of the die. The clamping jaws may be part of the walls of a tunnel into which are forced the die 3 covered with the blank. The jaws 5 may be replaced by two stationary pairs of cams and the jaw 7 by a cam. |
