PURPOSE: To continuously obtain the square cylinder useful for simplified packed containers or the like with high accuracy and productivity by a method wherein continuous thermoplastic plastic is fed at constant speed and, after being incised with a desired number of fold lines, bent along the fold lines into square cylinder and jointed at the overlapped edges and then cooled.
CONSTITUTION: A series of the fold lines (a) are incised on the continuous thermoplastic plastic sheet S fed at constant speed by means of a fold line incising device 1 comprising a heating zone 1b equipped with heaters H, the number of which corresponds to the desired number of the fold lines (a), and V- grooves 2 cut on the extension of the heating zone 1b and press rolls 3, all of above-mentioned ones are arranged on a bedplate 1b. Next, the sheet S is fed to a square cylinder forming device 4 side and gradually bent up at the fold line parts (a) while passing through a forming part 4a and, after that, formed into square cylinder at a square column mandrel 4b and then its overlapped edges are joined by a joiner 4c in order to obtain the objective square cylinder.
YABUUCHI HIDEAKI
YONEMOTO TAKAMI
FURUKAWA YASUMITSU
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