Easy opening ecology end with retained tear strips
BACKGROUND OF THE INVENTION 
     This invention relates to easy opening cans and, more specifically, to an improved easy opening container wall including inseparable tear strips, each defined by a separate score line, wherein the tear strips may be opened with a single retained tab member, and wherein protective means are incorporated in order to reduce the incidence of laceration. 
     The ready acceptance of easy opening containers has resulted in extended use of this type of container for a substantial number of canned products, especially beverages such as beer, soft drinks and the like, as well as other products which are non-carbonated. This type of container is characterized by a lever or tab permanently joined to a tear strip, the latter normally bein separable from the can top to provide a pouring spout, in the case of beverages. In the form heretofore used, the tab or top is ruptured along a continuous score line and the pull tab and tear strip is normally removed and discarded. 
     The convenience of easy opening cans has created problems because of the unfortunate and indiscriminate disposal of the severed portion of the can top. For example, beach and picnic areas have had an accumulation of litter in the form of tabs and tear strips which have been removed from easy opening cans. These discarded tabs and tear strips are quite difficult to clean up because they are small and thus pass through the tines of a rake. Being made normally of aluminum, they cannot be collected by magnetic means. Nonetheless, this type of can is widely used and it is definitely advantageous to provide a solution to the problem of littering while still providing to the public the convenience of easy opening containers. 
     The numerous advantages incident to the use of easy opening cans are significantly enhanced if a container end is provided including an inseparable tear strip and which is relatively safe to use in the sense that the incidence of lacerations are reduced. As will be appreciated, where a tear strip is not separable from the end wall, precautions must be taken to prevent laceration by the retained tear strip or by the exposed edge of metal formed upon opening of the container. This is particularly true with respect to small children who exhibit a tendency to place their fingers down into the pour opening of an easy opening container. 
     The packaging industry is generally aware of the problem of indiscriminate littering of separable tabs and tear strips as well as the potential problem of laceration. 
     Accordingly, it is definitely advantageous to provide an easy opening end wall structure with a retained tear strip system in that there are no detachable components which may be thrown away as litter. In such an end structure, it is desirable to retain, to the extent possible, the opening action, which is in the form of lifting to bring about rupture of the score lines, since the public is accustomed to this type of opening action in an easy opening end wall. 
     It is also advantageous to provide an easy opening end structure having the advantages previously noted that is a conversion and interchangeable with present tooling used by the industry in the sense that the basic container dimensions need not be altered in order to accommodate the improved end. An additional factor is that the end should provide normal performance for the variety of products packaged in convenient easy opening end type containers, for example, an end structure which is capable of withstanding the normal pressures utilized in the beer and beverage industry, and particularly those products packaged under pressure or which develop pressure during their packaging, for example, pasteurization of certain beer type products. 
     DESCRIPTION OF THE PRIOR ART 
     It is known to use a noncontinuous score line such that the tear strip is firmly attached to the container. Such a structure is shown in U.S. Pat. No. 3,327,891. 
     An improvement in the structure described in the above-identified U.S. Patent is described in U.S. application Ser. No. 103,255, filed Dec. 31, 1970, as well as U.S. application Ser. No. 346,712, filed Mar. 30, 1973, each assigned to the same assignee as this application. 
     Recently, beverage and beer containers have appeared in commercial use which include a push type opening which is ruptured by pushing downwardly upon a panel and folding it into the container. This type of structure is objectionable principally because of the laceration problem since it is necessary for the user to place his finger through the pour opening during the opening operation. 
     SUMMARY OF THE INVENTION 
     The present invention relates to an easy opening container wall structure which offers several distinct advantages not heretofore found in prior devices. The container end wall of the present invention includes a retained tear strip structure in that the tear strip cannot be discarded once the pour opening has been formed. Moreover, recognizing the need to provide an easy opening container which vents properly during the opening sequence, the end wall of the present invention includes a separate vent opening, the pour opening and the vent opening being provided in a single opening sequence which follows generally the opening operation heretofore used with the more conventional easy opening container ends. 
     More specifically, the easy opening wall of the present invention includes an end wall and a first line of weakness in the end wall which defines a tear portion partially removable from the end wall to form a pour opening. Also provided in the end wall is a second line of weakness, spaced from the first line of weakness, and defining a vent tear portion partially removable from the end wall to form a vent opening. A tab structure is attached to each of the tear portions, preferably by an integrally formed rivet, and is used to rupture the lines of weakness and is likewise retained on the end wall after the opening sequence. 
     Each line of weakness includes an associated means for preventing complete removal of the ruptured tear strips. Accordingly, as the tab is manipulated to rupture the score lines, inseparable tear strips are formed which are joined to the tab and the tab and tear strips can be folded back against the end walls of the container, out of the way of the user, but retained on the container end wall. 
     Another feature of the present invention is the provision of protective means associated with the tear strip which forms the pour opening and the residual metal which surrounds the pour opening. In one form, a raised protective bead is formed adjacent to the score line forming the pour opening thereby substantially reducing the possibility of laceration. It will be appreciated, that the system described for protecting against laceration is not fool proof but operates substantially to reduce the possibility of laceration by virtue of a beaded formation which tends to prevent the user&#39;s finger from coming into cutting contact with the free edge of metal surrounding the pour opening. 
     The tear strip which is partially severed to form the pour opening likewise includes a beaded formation which performs several different functions. With the beaded formation in accordance with the present invention, it is in the form of a downwardly extending depression such that the pressure from the interior of the container operates to maintain the adjacent score line in compression thus increasing the strength of the score line to some extent. Moreover, the depression acts as a strengthening means to prevent the bending of the ruptured tear strip thereby allowing it to be hingedly folded back against the end wall. In the open and folded position, the depression now appears in the form of a protrusion which prevents the user&#39;s fingers or nose or lips from coming into contact with the sharp edges which are formed along the severed portion of the tear strip. 
     The vent opening and the pour opening, as already described, cooperate with the tab to form a hinge line by which each of the tear strips is hingedly foldable against the end wall of the container. In a preferred form, the distance from the center of the rivet to the hinge line at the vent opening is less than the distance from the center of the rivet to the hinge line of the pour opening such that one end of the tab is rotated through a greater arc than the other end of the tab. 
     The end structure also includes depressions in the end wall, one cooperating with the tab to permit the user&#39;s finger to be inserted beneath the tab, and the other positioned such that the folded vent strip and pour strip may be pushed flat against the end wall by pushing the tab into the depression. This latter depression generally follows the contour of the tab itself and in effect forms a tab receiving pocket. 
     Further objects, advantages, and modes, and such additional embodiments of the present invention will be readily apparent to those skilled in the art after they have read the detailed description and referred to the accompanying drawings which illustrate what are presently considered to be preferred embodiments of the best mode contemplated for utilizing the novel principles which are defined in the claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view, on a somewhat enlarged scale, of a container end wall in accordance with the present invention; 
     FIG. 2 is a view similar to FIG. 1 with the tab structure removed so that further details of the structure of the container end wall of the present invention may be seen; 
     FIG. 3 is a view in section, with portions thereof being in elevation, taken along the line 3--3 of FIG. 2; 
     FIG. 4 is a view, partly in section and partly in elevation taken along the lines 4--4 of FIG. 2; 
     FIG. 5 is a view, partly in section and partly in elevation taken along the lines 5--5 of FIG. 1; 
     FIG. 6 is a fragmentary view, in perspective, of the container end wall of the present invention illustrating the relative position of the parts during the start of an opening sequence; 
     FIG. 7 is a view similar to FIG. 6 but illustrating the relative position of the parts after complete severance of the vent opening and pour opening in accordance with the present invention; 
     FIG. 8 is a view similar to FIG. 6, showing the tab structure and vent and tear openings being folded back in accordance with the present invention; 
     FIG. 9 is a plan view of a container end wall in accordance with the present invention, on a somewhat enlarged scale, showing a modification of a tab structure usable in accordance with the present invention; and 
     FIG. 10 is a view, partly in section and partly in elevation taken along the lines 10--10 of FIG. 9. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to the drawings which illustrate a preferred form of the present invention, FIG. 1 illustrates a container end wall generally designated 10, the container end wall being formed of sheet material as, for example, aluminum alloys and the like or any of the other materials capable of being used in the formation of end walls for convenience type containers. A typical such alloy is 5082H19 of a thickness of 0.0135 inches. The container end wall 10 includes an end wall panel 12 and a peripherally extending flange 13 (FIG. 4) joined to the end wall panel by a chuck wall 14. The container end wall 10 is attached to a container body in the usual manner, well known in the art. 
     The end wall panel 12 includes a first line of weakness 15 in the form of a score line which is noncontinuous in the sense that it does not extend in a full 360° circle. The first line of weakness defines a tear portion 17 which is at least partially removable from the end wall, the removal of the tear portion 17 forming a pour opening. Spaced from the first line of weakness 15 is a second line of weakness 18 in the form of a score line, defining a tear strip 19, the latter likewise being partially removable to form a vent opening. The score lines may be of the conventional V-shaped score type, or a pinched score line, as is known in the art, may be used. 
     A tab element generally designated 25 is attached to each of the tear portions 17 and 19 by integral rivets 27 and 29, respectively. The end wall panel 12 also includes a plurality of depressions 30 and 31, depression 30 forming a tab receiving depression and tab 31 forming a finger well to enable the user to insert his finger between the end wall panel and the underside of the tab 25 in order to operate the tab in an opening sequence. 
     Referring now specifically in FIG. 2, each of the lines of weakness 15 and 18 is configured to prevent removal of the associated tear panel. To accomplish this, score line 15 terminates in reversing curves 33 and 34, as illustrated, while score line 15 likewise terminates in reversing curves 36 and 38, the reversing curves 33-34, and 36-38, operative to prevent continued tearing of the metal as the vent strip and pour strip are ruptured by the tab 25, as will be described hereinafter. 
     As in known, the rupture of sheet metal to form a pour opening frequently results in the formation of sharp peripheral edges, on each of the end panel and on the tear strip. Accordingly, in accordance with this invention, protective means are provided both on the end panel and the pour strip to provide protection against laceration. 
     Referring to FIGS. 2-5, the end wall 12 in the portion thereof surrounding the score line 15 which forms the pour opening includes a generally annular raised flat 40, the flat in turn including a protective bead 42 which circumscribes that portion of the end wall which defines the pour opening. As illustrated, the score line 15 is located on the raised flat 40 and closely adjacent to the protective bead 42. Thus, as the score line 15 is ruptured, the amount of laterally extending residual cutting edge is reduced. Moreover, the presence of the protective bead 42 tends to inhibit contact between the free edge and the user&#39;s finger. As shown in FIG. 2, the ends 46 of the protective bead 42 terminate a short distance from the reversing curves 36 and 38. Since the vent opening normally does not create any problems with respect to laceration due to its relatively small opening, it is not necessary to provide the vent opening or the vent tear strip with any form of protective bead or other form of protective device. 
     In order to protect the user from laceration by the portion of the end wall panel which constitutes the pour opening tear strip 17, the latter is provided with a downwardly extending depression 50, which in addition to forming a protective means forms several other functions as will be described. 
     As illustrated in FIGS. 2 through 5, rivet 27 is positioned in a rivet well 52 formed in panel 17, the rivet well being generally planar and at approximately the same vertical level as the raised flat 40. Cooperating with the rivet well is a generally arcuate, sloping wall 53 whose maximum relative dimension is illustrated in FIG. 4 and which generally decreases in dimension to the right and to the left of the section line 4--4 of FIG. 2. The sloping wall 53 operates to permit the rivet to be placed in a flat plane while likewise permitting the downward depression 50 to be formed into the tear panel 17 which forms the pour opening. 
     One function of the downward depression 50 is to maintain the associated score line 15 in compression, especially in those instances in which the contents in the container are under some pressure. Referring to FIG. 3, for example, pressure on the underside 54 of the depression 50 operates to maintain the score line 15 in compression. In this way, score line integrity is enhanced, particularly in those instances in which the contents of the container are under considerable pressure as may be the case with certain types of carbonated beverages. Score line integrity is also important in those instances in which the processing involves the use of a pasteurization step which creates substantial pressures during the pasteurization operation. The downward depression 50, in that particular instance, also acts to prevent considerable bulging of the container end in the sense that the container end takes a permanent set in the domed configuration. 
     Referring to FIGS. 6 through 8 wherein like reference numerals have been applied, the opening sequence of the container end wall may be understood, as well as the additional functions performed by the protective depression 50. As illustrated in FIG. 6, the user inserts his finger between the tab 25 and the finger well 31 and lifts the tab 25 in an upward direction, following generally the operation used in opening a beverage container having a ring type pull tab. During the initial movement of the tab 25, the score lines 18 and 15 are stressed, preferably such that score line 18 begins to rupture immediately prior to the start of rupture of score line 15. As long as the vent score line 18 starts to rupture immediately prior to, or simultaneously with the rupture of score line 15, the venting action sought to be achieved in accordance with the present invention is obtained. Thus, the initial manipulation of the tab is effectively a rotating action in the sense that the end 56 of the tab is lifted upwardly and the edge portion 57 is rotated downwardly in stressing the score lines 18 and 15 in the portions generally designated 58 and 59, respectively. Since the single tab 25 is attached at its ends 61 and 62 to rivets 29 and 27, respectively, the manipulation of the single tab element is effective simultaneously to open both score lines either simultaneously or with the score line of the vent opening being initially popped slightly ahead of the score line for the pour opening. 
     As the user continues to manipulate the tab 25 by a rotating lifting action towards a vertical plane, the score lines 15 and 18 are ruptured to the point of the reversing curves associated therewith which, as earlier indicated, operate to prevent complete severance of the vent tear strip and the pour strip from the end wall. Thus, a fold zone 65 exists, as illustrated in FIG. 1 between lines 65a and 65b which effectively forms a hinge line for the vent panel and pour panel resulting from severance of the score lines 15 and 18. 
     As illustrated in FIG. 1, the center point from rivet 29 to the fold zone is substantially less than the distance from the center of rivet 27 to the fold zone 65. Accordingly, to effect complete severance of the score lines while providing the retained tear strips, it is necessary that the end 62 of the tab 25 move through a greater arcuate distance vertically above the end wall than the end 61. 
     Referring to FIG. 7, the general vertical orientation of the tab 25 attached to the tear strips 67 and 69 is illustrated, as well as the difference in vertical heighth above the end wall of the ends 62 and 61 of the tab 25. 
     In the type of opening action described, it is important that the tear strip 69 be folded about the fold zone 65 rather than midway or part way through the panel. Accordingly, another function of the depression 50 is to provide structural integrity to the tear strip 69 thereby assuring that it folds along the fold zone 65 rather than folding in the middle. Since the length of tear strip 67 is relatively short, no reinforcement is needed since the legs 71 and 72 of the score line are relatively short from the center point of the rivet to the reversing curves 33 and 34. 
     Once the tab has been elevated to the vertical position with the tear strips oriented generally in a vertical position, it is possible for the user to continue to rotate the tab around the fold zone 65 and to push the tab 25 into the tab receiving well 30. Such a relative position is indicated in FIG. 8 with the tab in its initial position indicated by the dotted lines 74. 
     In the opened condition, as illustrated in FIG. 8, with the tab 25 pushed into the tab receiving pocket 30 and with the tear strips folded about the fold zone 65, depression 50 now appears as a protrusion rising above the folded pour strip 69. The protrusion 50 which extends above the surface of the end panel protects the user from contacting the exposed edges on the tear strip 69 since the panel is folded against the end wall and in contact therewith by virtue of the fact that the depression 30 receives the tab. Thus, the protective depression, now operating as a raised projection, assists materially in preventing the user&#39;s nose or fingers from contacting the exposed edge of metal along the periphery of the panel 69. 
     As seen in FIG. 5, the rivet 27 is somewhat vertically above the rivet 29 and in order for the tab 25 to lay flat against the end panel of the container end wall, it includes a vertically raised section 80 at the end 62 thereof to which the rivet 27 is attached. The other end 61 is attached to rivet 29, with the portion 80 being raised along a generally angularly disposed line 83 as seen in FIG. 1. 
     While the above structure operates effectively and in the manner described, it will be apparent that modifications may be made. For example, referring to FIGS. 9 and 10 wherein the same reference numerals have been used where applicable, the tab 95 is attached to the rivets 29 and 27, the tab including a fold shoulder 96 at the junction between the body portion 98 and the end 99 attached to the rivet 27. The fold shoulder operates to contact the end panel of the container during the operation of the tab thereby permitting somewhat easier rupturing of the score line 15 in the tear panel which forms the pour opening. 
     In all other respects, the end panel is essentially the same as that previously described. 
     The end structure of the present invention may be easily manufactured in a series of operations on an end blank. For example, that tab well and finger well are first formed, the depression and bead are then formed, the scoring then placed, and finally the tab is staked. It is understood that the rivet button may be formed in the bubble and button stages or what is called a single hit rivet. 
     While the pour opening has been shown as generally circular in shape, other shapes may be used because of the presence of a vent opening separate from the pour opening which substantially improves the pouring characteristics of a container with an end wall as herein described. 
     It is to be understood that depression 50 may be a protrusion if only a stiffening means is needed to prevent the pour panel from folding during an opening sequence. Where protection and increased score integrity are also desired, the depression will achieve all three functions, as described. 
     One of the definite practical advantages of the present invention is the fact that venting is easily accomplished by a separate vent opening located in a portion of the end panel other than where the pour opening is located. Also, since the tab is rigidly held by rivets to the tear panels which are inseparable from the end wall and folded into the tab receiving recess 30 after opened, there is little tendency to remove the tab from the tear strips to which it is attached. Since the entire opened end of the end wall is folded back, it is, in a sense, out of the user&#39;s way and there is no need for any further manipulation of the tab or the tear strips during the dispensing of whatever material is within the container. 
     Another practical advantage of the end structure of the present invention is the fact that the pouring characteristics of the container are enhanced considerably by the use of a separate vent opening. As shown in the drawings, the pour opening is located closely adjacent to the chuck wall which places the vent opening in the upper quadrant of the container during a normal pouring operation. This permits air to come in through the top of the container while liquid is being dispensed from the lower end, in a pouring operation. It is for this reason, that the rivets are located on a straight line which defines a cord with respect to the end wall, the cord being so located as to permit the tab and retained but fractured tear strips to be folded back into the end wall and out of the way of the pour opening and the vent opening. 
     Thus, the container end structure of the present invention offers several advantages over the prior art structure including a retained tear strip structure and more importantly a retained tab structure which is not easily removed from the tear strips. Means are provided to protect the user against laceration, and there is no need for the user to insert a finger into the pour opening. Even so, if this is done, there is a measure of protection provided by the protective beads which surround the major portion of the pour opening, as described, and thus protection is afforded against laceration. Accordingly, the combination of a retained tear strip, attractive from an ecology standpoint, with the protective features as described, and the highly desirable pouring characteristics all offer a combination of advantages which are sought after in the design of container end structures. 
     It will be apparent to those skilled in the art that there are several features of the present invention. Thus, many modifications and alterations of the disclosed and described embodiments may be made as will be apparent to those skilled in the art, without departing from the scope of the invention as defined in the following claims.