A method of forming an integral rivet in a sheet element including providing cooperating male and female dies and an interposed sheet element, moving the male die toward the female die to draw an outwardly directed hollow boss. Continuing movement of the male die toward the female die to thin an annular region in the lower portion of the hollow boss by compression which establishes metal flow substantially entirely in the direction of the upper portion of the hollow boss. Continuing relative closing movement of the male die with respect to the female die to establish an annular band of thinned material extending upwardly toward the upper portion of the hollow boss, whereby the upper portion of the hollow boss has a thickness substantially equal to the thickness of the remainder of the sheet element. The sheet element may be peripherally restrained around the area in which the boss is formed during boss formation. Apparatus for fabricating an integral rivet in sheet material including a male die having a convexly curved sheet contacting surface and a rearwardly disposed generally cylindrical surface. A female die having a bore defining wall and a peripheral material supporting surface disposed substantially perpendicular to the bore defining wall. An annular concave transition surface connecting the bore defining wall and the material supporting surface. The radius of curvature of the sheet contacting surface and the radius of curvature of the annular concave transition surface being such that movement of the male die toward the female die establishes relative closing movement between the dies which occurs initially at the outer portion of the annular concave surface of the female die and progresses inwardly along the surface as male die movement continues.
An improved method of deforming an integral hollow rivet from an outwardly projecting bubble portion formed in sheet material is provided comprising the step of deforming a generally circular portion of the sheet material within the area of the bubble portion inwardly of the general plane of the sheet material, during the step of deforming the bubble portion into a hollow rivet.
A dual function device for pressing a workpiece in a single stroke of a press ram comprises a housing that carries first and second tools each having a working end that protrudes from one end of the housing. The housing can be removably attached, at an end opposite the one end, to the press ram. The first tool has a shank portion that includes a piston slidable in a piston chamber formed in the housing. Pressurized liquid may fill the piston chamber to hold the first tool in an extended protruding position with its working end protruding farther from the housing than the working end of the second tool. The device further includes a relief valve that selectively and controllably permits liquid to be exhausted from the piston chamber when the liquid pressure exceeds a predetermined limiting value. Therefore, as the press ram is operated through a single stroke, the first tool first contacts the work piece to perform one function. When the press ram pressure and, hence the pressure applied to the work piece causes the pressure of the liquid to exceed the predetermined limiting value of the relief valve, the valve operates to permit liquid to be exhausted from the piston chamber. The first tool then may retract into the chamber. Thereafter, during further operation of the press ram through its stroke, the working end of the second tool is moved beyond the working end of the first tool to press the workpiece and perform a second function.
An easy opening device is provided which includes a score line in the container wall defining an opening flap adjacent an edge of the container wall and a tab having a nose end overlying the opening flap and affixed thereto and a handle end toward the opposite edge of the container wall with a line of weakening in the tab between its nose and handle ends for depressing the handle end of the tab to a nonobstructing position on the container wall, and which further includes an upwardly embossed hook in the container wall for engagement over an edge portion of the handle end of the tab to restrain it in a non-obstructing position on the container wall. A method of forming an embossed hook for engaging a tab is also provided.
A planar material to be press-formed is confined in a space having a contour corresponding to the outer contour of the flange part of an article to be produced and is pressed between a punch member having a through hole corresponding to the outer contour of the hollow main part of the article and another die member holding slidably a mandrel having an outer contour corresponding to the inner contour of the internal bore of the hollow article, the mandrel being simultaneously projected into the through hole of the first member. By the pressing action, the peripheral part of the material is formed into the flange part of the article while an inward flow of the material is caused, thereby elevating the surface of the material in the through hole of the punch member and forming a recess in the opposite side surface of the material. The mandrel is projected simultaneously with said pressing action, whereby topless hat-shaped product is easily formed by one step.
