Abstract:
An easy opening end closure is formed with annular, double folded band adjacent the chuck wall. A weakening line defining a removable panel portion is formed in the center segment of the fold so that the folded edges of the single band provide smooth protective surfaces on both the ledge and the removable panel portion. 
     This disclosure also relates to a method for forming the above described easy-opening end closure wherein the weakening line is formed in the end panel prior to complete formation of the folded band.

Description:
This is a continuation, of Ser. No. 641,472, filed Dec. 17, 1975. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to new and improved easy opening end closure of the full panel opening type and more particularly to the method of forming the same. 
     Full opening containers of the type to which the present invention relates include an end closure of which the end panel is formed with a weakening line located closely adjacent the chuck wall. The weakening line is formed by scoring and defines a removable panel section to which there is attached a pull tab. The pull tab is mounted so that upon initial lifting thereof the nose of the tab penetrates the weakening line to initiate the severance of the removable panel section from the end panel. Thereafter, the pull tab is pulled upwardly so that the remainder of the weakening line is ruptured and the removable panel section separated from the remainder of the panel substantially in the form of a disc. 
     The opening thus formed in the end closure is bounded by a horizontal ledge which terminates in a sharp raw edge caused by the severance of the removable panel portion therefrom. This sharp edge presents a hazard. 
     The edge on the removable portion is also sharp. 
     Folded end panels for edge protection are known in the art as, for example, Holk, U.S. Pat. No. 3,848,557. However, in the prior art, a fold band protects a single edge only and two bands are required to protect the edges of both the ledge and the removable panel. The requirement of two fold bands complicates the production process and increases the probability of rejection of the closure due to accidental fracture of the score line during fabrication. 
     SUMMARY OF THE INVENTION 
     By the present invention, it is proposed to provide a full opening easy-open end closure constructed and arranged so that the raw edges about the horizontal ledge and the removable panel are protected after severance of the removable panel portion. It is thus seen that the folded band comprises a first closed fold portion on the ledge having a folded edge facing inwardly, and a second closed fold portion on the panel having a folded edge facing outwardly, the folded edge on the panel being radially outward of the folded edge on the ledge. 
     This is accomplished generally by an end closure having an annular, double folded-band formed in the end panel adjacent the end closure chuck wall and in which a weakening line is formed in the center segment of the fold, so that the folded edges of the band provide smooth surfaces which bound the opening and the removable flap after separation. 
     It is another object to provide a new and novel method for forming a full opening easy-open end closure constructed in the manner specified in the foregoing object. 
     This is accomplished by forming the annular folded band in stages and the weakening line is formed by scoring prior to the final fold steps. 
     With the above and other objects in view that will hereinafter appear, the nature of the invention will be more readily understood by reference to the following description, the appended claims and the several views illustrated in the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING 
     FIG. 1 is a top plan view of a full opening easy-open end closure incorporating the easy opening structure of the present invention. 
     FIG. 2 is a fragmentary cross-sectional view of an end panel illustrating a step in the formation of the end closure of FIG. 1. 
     FIG. 3 is a fragmentary cross-sectional view similar to FIG. 2, illustrating another formation step. 
     FIG. 4 is a fragmentary cross-sectional view similar to FIGS. 2 and 3, illustrating yet another formation step. 
     FIG. 5 is a fragmentary cross-sectional view taken substantially along line 4--4 of FIG. 1. 
     FIG. 6 is a fragmentary cross-sectional view similar to FIG. 5, illustrating the tab being lifted to open the closure. 
     FIG. 7 is a fragmentary cross-sectional view illustrating the portion of the end closure attached to the container after opening. 
     FIG. 8 is a fragmentary cross-sectional view illustrating the portion of the end closure removed from the container during opening. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     In accordance with the present invention, there is provided an easy-open end closure comprising an end panel 1 and a pull tab 2. 
     The end panel 1 includes a substantially horizontally extending central panel 3 having at its periphery a chuck wall 4 which terminates in a horizontal flange 5 and a curled end 6. The central panel 3 is formed with an annular, double-folded band 7, radially inward of the chuck wall 4. As best seen in FIG. 5, the band 7 comprises substantially planar upper, intermediate and lower segments 7a, 7b and 7c respectively and curved segments 7d and 7e, the curved segments 7d and 7e connecting the planar segments 7a, 7b and 7c in an S-shaped series with the planar segments being substantially parallel and in close contact. A score line 8 is formed in the intermediate segment 7b, in the side thereof toward the lower segment 7c, and encircles an opening flap 9. The portion of the central panel 3 radially outward of the score line 8 is commonly referred to as the ledge, while the portion radially inward thereof is known as the removable panel portion or closure portion. 
     The pull tab 2 is longitudinally rigid and comprises a nose portion, an intermediate portion and a lift portion 2a, 2b and 2c respectively. The tab 2 is attached to the end panel 1 by a rivet 11, integrally formed in the central panel 3 in the portion thereof radially inward of the score 8. The rivet shank 11a passes through an opening 12 in the intermediate portion 2b with the rivet head 11b pressing against the upper surface of the tab 2. A horse-shoe shaped slit 13 is formed in the intermediate portion 2b encompassing the rivet 11 and opening toward the nose portion 2a. The nose portion 2a terminates in a substantially vertical end member 14 which engages the central panel 3 at a point 15 between the chuck wall 4 and the fold band 7. 
     To open the closure, the lift portion of the tab 2 is displaced vertically, causing the tab 2 to pivot about the point of contact 15 between the end member 14 and the central panel 3 and impressing a downward force on the lower segment 7c and intermediate segment 7b of the fold band 7. At the same time, the intermediate portion 2b of the tab 2 is exerting an upward force on the rivet head 11b at the point 16 thereon nearest the end member 14. This upward force is communicated to the upper segment 7a of the fold 7 through the rivet shank 11a. The opposing forces thus placed on the intermediate segment 7b result in fracture of the score line 8 in the area immediately adjacent the end member 14. After fracture has been initiated, the tab 2 is pulled away from the end panel 1 in the conventional manner to effect controlled tearing of the remainder of the score 8 and removal of the flap 9. 
     As may be seen in FIGS. 7 and 8, the sharp edges created by the tearing of the score 8 are in shielded positions abutting the upper and lower segments 7a and 7b of the fold band 7. The flap 9 and the periphery of the opening in the central panel 3 present the harmless turned smooth surfaces of the curved segments, 7d and 7e respectively, to the user and others coming into contact with the closure. 
     Referring to FIGS. 2, 3, 4 and 5 illustrating the stations for forming the end closure of the present invention, in FIG. 2 there is illustrated a first station for forming the same. In this station, the end panel 1 has already been formed with a chuck wall 4, flange 5 and curl 6 by means well known in the art. In addition, the center of the central panel 3 has been upset to form a section 3a axially spaced from the remaining section 3b of the panel 3, the two sections 3a and 3b being joined by a connecting portion 3c having formed therein a score line 8. Although it is preferred that the connecting portion 3c be formed as a substantially horizontal ledge 3d and two substantially vertical members 3e and 3f, and that the score line 8 be located on the upper surface of the ledge 3d, it is to be understood that other connecting portion configurations and score locations therein are contemplated in the present invention. The end panel 1 rests on an anvil 21 which provides support for the flange 5 and chuck wall 4 and both sections 3a and 3b of the central panel 3. A punch 22 is provided which is configured to fit between the chuck wall 4 and the uppermost vertical member 3f of the connecting portion 3c. 
     In FIG. 3, the punch 22 has been displaced vertically toward the anvil 21, thereby upsetting the connecting portion 3c such that the ledge 3d assumes a substantially vertical position. It is to be noted that the score line 8 is displaced radially inwardly during this operation. This reduction in the length of the score 8 results in the forces impressed thereon during the reformation being primarily compressive rather than tensile. This avoidance of tensile loading prevents score fracture during the forming process. 
     In the second forming station, illustrated in FIG. 4, there is provided a split anvil 41 and a split punch 42, each comprising a central movable portion 41a and 42a respectively and an outer fixed portion 41b and 42b respectively. The partially formed end closure from the first forming station is clampingly held between the fixed portions 41b and 42b of the punch 42 and the anvil 41. The movable portion 42a of the punch 42 is then displaced downwardly, causing a corresponding downward movement of the movable portion 41a of the anvil 41. As the punch portion 42a descends, the connecting portion 3c collapses, rotating outwardly and downwardly about a point 43 at the juncture of the connecting portion 3c and the lower portion 3b of the central panel 3. The collapsing connecting section 3c is constrained to move between the opposing faces 44 and 45 of the fixed portion of the punch 42b and the movable portion of the anvil 41a. As the punch 42 descends, the upper end 46 of the connecting portion 3c encounters the punch face 44. As the punch continues downward, the lower end 43 of the connecting portion 3c is forced against the moving face 45 of the anvil 41. It is to be noted that the punch face 44 is substantially vertical while the anvil face 45 slopes upwardly and inwardly.  Thus, the score line 8 is again displaced radially inwardly while being subjected to a primarily compressing loading. After the connecting portion 3c has been folded flat against the lower central panel portion 3b, the pull tab 2 is attached to the upper panel portion 3a with an integrally formed rivet 9 according to methods well known in the art.