Abstract:
An improved easy-opening end closure of the full panel pull-out type, wherein the pull tab includes an integral tether cooperating with the tab attachment rivet to redistribute the opening stresses impressed on the pull tab during opening, whereby tearing of the pull tab is prevented.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention relates to containers and the like and is particularly concerned with containers having easy-open closure means. 
     End closures of the full panel pull-out type frequently employ a pull tab having an intergrally formed hingeable panel member providing for a measure of displacement of the tab relative to the end panel. Unfortunately, the stresses impressed on the tab during opening of the closure are often such as to cause tearing of the hinge portion thereof, resulting in malfunction of the closure. 
     It is therefore a primary object of the present invention to provide an improved full panel pull-out type end closure wherein tearing of the pull tab is prevented. 
     This is accomplished by providing a pull tab having an integrally formed force-distribution tether cooperating with the tab securing means to reduce the stresses impressed on the hinge portion during openings. 
     Reference is herein made to my co-pending U.S. application Ser. No. 684,620 filed herewith in the name of Nick S. Khoury and entitled Non-Obstructing End Closure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     With the above and other objects in view that will hereinafter, the nature of the invention will be more clearly understood by reference to the following description when viewed light of the accompanying drawings, in which: 
     FIG. 1 is a fragmentary top plan view of the end closure of the present invention. 
     FIG. 2 is a top plan view of the pull tab of the closure of FIG. 1 prior to assembly to the end panel. 
     FIG. 3 is a fragmentary cross-sectional view taken substantially along the line 3--3 of FIG. 1, illustrating the end closure in the unopened condition. 
     FIG. 4 is a fragmentary cross-sectional view similar to FIG. 3, illustrating the end closure in a partially opened condition. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     As shown in the drawings, the improved easy-open end closure of this invention comprises an end panel 1 having an intergrally formed rivet 2 and a pull tab 3 fixedly attached to the end panel 1 by the rivet 2. A score line 4 is formed in the end panel 1 and encircles an opening flap 5. 
     As best shown in FIG. 2, the pull tab 3 comprises a nose portion 3a and a grasping portion 3b. 
     The nose portion 3a includes a rupturing member 7 overlying the score line 4 and a generally circular recessed rivet well 8. The well 8 comprises a sloped sidewall 8a and a substantially horizontal base 8b. A generally horseshoe-shaped slit 9 is formed in the base 8b, opening toward the rupturing member 7, and defining a hingeable panel member 10. The panel member 10 is integrally connected to the remainder of the rivet well base 8b by an unslit area 8c in the panel member perimeter. Located in the well base 8b, is a hole 11 of a size to admit the shank of the rivet 2, but not the rivet head. 
     A tether 12 is integrally connected to the nose portion 3a on the side thereof away from the rupturing member 7. A slot 13 is formed in the tether 12, elongated along the axis of the tab 3 and being of a width to permit the passage of the shank of the rivet 2, but not the rivet head. 
     The grasping portion 3b comprises a substantially C-shaped handle member which combines with the nose portion 3a to define an aperture 14 through the tab 3. During the formation of the tab 3 from a single piece of sheet metal, the tether 12 is formed of material displaced to form the aperture 14. 
     A panelwardly directed rigidifying curl 15 is formed in the periphery of the tab 3 and protects the user from possible injury resulting from contact with the sharp edges of the tab 3. 
     In assembly of the end closure, the tether 12 is folded under the nose portion 3a and toward the rupturing member 7. The rivet 2 passes through the slot 13 and engages the panel member 10. To open the closure, the grasping portion 3b of the tab 3 is lifted away from the end panel 1, thereby impressing a panelward force on the rupturing member 7 of the nose portion 3a and resulting in rupture of the score line 4. Continued lifting of the grasping portion 3b results in controlled tearing of the end panel 1 along the score line 4. During the operation, the tab 3 pivots initially about the point of contact between the rupturing member 7 and the end panel 1. As the end panel 1 tears, the fulcrum is located on a line connecting the ends of the torn portion of the score line 4. 
     As the tab 3 is rotated, the unslit area 8c of the panel member perimeter is subjected to a tensile stress. In the prior art end closure, which lacked a tether 12, this stress occasionally resulted in tearing of the tab area 8c and malfunction of the closure. 
     In the end closure of the present invention, the tether 12 is initially in a slack condition, with the rivet 2 abutting the end of the slot 13 further from the rupturing member 7. As the tab 3 is lifted, the tether 12 is drawn back until the rivet 2 abuts the end of the slot 13 nearer the rupturing member 7 just prior to rupture of the score line 4. Continued lifting of the tab 3 beyond a predetermined angular displacement results in stressing of the tether 12. Thus, the stresses formerly impressed on the unslit area 8c are now partially borne by the tether 12. This reduction of the stress loading on the area 8c prevents tearing thereof.