초록 ▼

An improved integral rivet button and resulting rivet, and a process and tooling for forming such button, utilizes successive coining steps on material surrounding the base of an initial bubble formed on a can end, causing flow of material along the wall of the button toward its center. The successi

An improved integral rivet button and resulting rivet, and a process and tooling for forming such button, utilizes successive coining steps on material surrounding the base of an initial bubble formed on a can end, causing flow of material along the wall of the button toward its center. The successive coining at progressively lesser radii affords adequate metal in the bubble region to assure ultimate formation of an accurate button, assures a strong boundary region about the base of the button, and assures the rivet head is sufficiently large to prevent tear out of the tab at its juncture with the rivet. The initial coined boundary is located close to the juncture of the initial bubble wall with the remainder of the shell, where curvature of the initial bubble wall is concave in the direction of the bubble top and toward the ultimate public side of the end. Subsequent coining at one or more locations radially inward from the initial coined boundary causes material to flow into the region from which the button ultimately is formed, and such material is reshaped into a precise button form having improved overall thickness and strength. Tooling design is such that intermediate shapes formed at progressive tool stations are compatible with next tooling stations to promote smooth transition of metal.

대표청구항 ▼

In a method of forming an integral rivet in a container end for attachment of a tab to the end, the improvement comprising the steps of a) displacing an area of metal from the plane of material of a generally flat shell to form a dome-like bubble consisting of the material from which the rivet is to

In a method of forming an integral rivet in a container end for attachment of a tab to the end, the improvement comprising the steps of a) displacing an area of metal from the plane of material of a generally flat shell to form a dome-like bubble consisting of the material from which the rivet is to be formed, said dome-like bubble being defined at its periphery by a generally circular first boundary where said region joins the remainder of the shell, b) coining the material of the shell around said first boundary and thereby causing metal flow into the dome-like bubble, then c) reshaping the bubble inwardly of the first boundary to heighten said bubble and d) coining the material of the thickened bubble wall about a second generally circular boundary which is of smaller radius than said first boundary, thereby causing a further flow of material from the second boundary into the bubble.