US 4,536,243 AGranted

Method and apparatus for making a metal can

AssigneeToyo Seikan Kaisha, Ltd.

InventorsTsuneo Imatani, Hisakazu Yasumuro, Michio Watanabe, Hideo Kurashima, Kazuhisa Ishibashi

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Abstract

A method of, and apparatus for, manufacturing a metal can (1) with an annular seam (5) which is capable of withstanding high internal pressures and resisting chemical action. A piece of thermoplastic tape is heat bonded to the outer surface (10a.sub.3) of the open end portion (10a ) of a first can section (10) so as to leave a portion (11a) projecting therefrom. After being bent radially inwardly of the first can section, the projecting tape portion is further folded back into forced contact with the inner surface (10a.sub.2) of the open end portion of the first can section by means of a mandrel (16). The open end portion of the first can section is then heated, with the fold of the tape held pressed against its inner surface by the mandrel, to cause adhesion of the thermoplastic tape to the outer surface, edge (10a.sub.1), and inner surface of the open end portion of the first can section. An adhesive layer (4) is thus provided. This open end portion of the first can section is then press-fitted in the open end portion (2a) of a second can section (2), and the joint (44) therebetween is heated to cause adhesion of the lapping open end portions of the can sections to each other via the adhesive layer.

Claims10

Dependent claims

A method of making a metal can having an annular seam formed by joining the open end portions of first and second can sections via an adhesive layer, said method comprising the steps of reducing the diameter of the open end portion of the first can section to provide a reduced diameter portion having an outside diameter substantially equal to the inside diameter of the open end portion of the second can section, heat bonding a piece of thermoplastic tape onto the outer surface of the reduced diameter portion of the first can section so as to leave a portion projecting therefrom, folding the projecting portion of the tape substantially radially inwardly of the first can section to cause part of the projecting tape portion to come into contact with the edge of the open end portion of the first can section, further folding the rest of the projecting tape portion into forced contact with the inner surface of the open end portion of the first can section by inserting a mandrel thereinto, causing thermal adhesion of the tape to the edge and inner surface of the open end portion of the first can section by heating the open end portion of the first can section to more than a temperature at which the tape is fusible, while part of the tape is held pressed against the inner surface of the open end portion of the first can section, inserting the reduced diameter portion of the first can section into the open end portion of the second can section, and causing thermal adhesion of that part of the tape which overlies the outer surface of the reduced diameter portion of the first can section to the inner surface of the open end portion of the second can section to form the annular seam by heating at least the open end portion of the second can section.

Apparatus for the manufacture of a metal can having an annular seam formed by joining the open end portions of first and second can sections via an adhesive layer, said apparatus comprising means for heat bonding a piece of heat-sealable plastic tape onto the outer surface of the open end portion of the first can section so as to leave a portion projecting therefrom, the open end portion of the first can section being reduced in diameter and having an outside diameter substantially equal to the inside diameter of the open end portion of the second can section;

means for heat bonding the projecting portion of the plastic tape to the edge and inner surface of the reduced diameter open end portion of the first can section, comprising a die having a first cavity for closely receiving the reduced diameter open end portion of the first can section with the plastic tape heat bonded thereto, an annular shoulder extending radially inwardly from the first cavity and having a width substantially equal to the sum of the wall thickness of the open end portion of the first can section and the thickness of the plastic tape, and a second cavity disposed opposite to the first cavity across the annular shoulder in concentric relationship thereto and having an inside diameter greater than the inside diameter of the open end portion of the first can section, a mandrel to be inserted into and through the second cavity in the die for pressing the projecting portion of the plastic tape against the inner surface of the open end portion of the first can section received in the first cavity in the die, the mandrel having a maximum diameter greater than the remainder of the inside diameter of the open end portion of the first can section minus twice the thickness of the plastic tape, and means for heating the open end portion of the first can section while the projecting portion of the plastic tape is pressed against the inner surface thereof;
means for inserting the reduced diameter portion of the first can section, with the plastic tape heat bonded to the outer and inner surfaces and edge thereof, into the open end portion of the second can section;
and means for heating the open end portion of the second can section having the reduced diameter portion of the first can section inserted therein, in order to cause heat bonding of that part of the plastic tape which overlies the outer surface of the reduced diameter portion of the first can section to the inner surface of the open end portion of the second can section.

Dependencies are inferred from the claim text.