US3837524A

US3837524A - Easy opening container wall

Info

Publication number: US3837524A
Application number: US00336404A
Authority: US
Inventors: O Brown; J Schubert
Original assignee: Individual
Current assignee: Individual
Priority date: 1972-03-27
Filing date: 1973-02-28
Publication date: 1974-09-24
Anticipated expiration: 1991-09-24

Abstract

An easy opening container wall comprising a container wall of sheet material having a line of weakness therein defining a tear portion at least partially removable from the container wall. Removal of the tear portion provides a relatively sharp edge along the tear portion. A guard is provided along the periphery of the tear portion to protect the consumer from injury. The guard is interrupted adjacent the location at which the line of score is initially ruptured to facilitate such initial rupture. The outer periphery of the guard and the score line are configured and positioned relative to each other to minimize interference by the guard during the opening operation.

Description

United States Patent 1 1 Schubert et al.

1 Sept. 24, 1974 EASY OPENING CONTAINER WALL [76] Inventors: James R. Schubert, 4243 Merrimac Ave., Dayton, Ohio 45405; Omar L. Brown, 148 Napoleon Dr., Dayton,

Ohio 45429 22 Filed: Feb. 28, 1973 [21] App]. No.: 336,404

Related US. Application Data [63] Continuation-impart of Ser. No. 238,187, March 27,

[56] References Cited UNITED STATES PATENTS Baugh et a1 220/54, Holk, Jr. 220/54 Primary ExaminerGe0rge T. Hall [57] ABSTRACT An easy opening container wall comprising a container wall of sheet material having a line of weakness therein defining a tear portion at least partially removable from the container wall. Removal of the tear portion provides a relatively sharp edge along the tear portion. A guard is provided along the periphery of the tear portion to protect the consumer from injury. The guard is interrupted adjacent the location at which the line of score is initially ruptured to facilitate such initial rupture. The outer periphery of the guard and the score line are configured and positioned relative to each other to minimize interference by the guard during the opening operation.

17 Claims, 12 Drawing Figures PATENIED sum 2 m 7 3.837. 524

, w a RN 7 III/II M 8 Q; v .m Mm m wg k [III/II PATENIEDSEPZMQH 3337.524 SIEH 30$ 7 NWN EASY OPENING CONTAINER WALL CROSS REFERENCE TO RELATED APPLICATION This application is a continuation-in-part of application Ser. No. 238,187 filed Mar. 27, 1972, for COM- BINED CAN AND END WITH MEANS FOR PRO- TECTING AGAINST SEVERED SCORE.

BACKGROUND OF THE INVENTION As is well known, when an easy opening container is opened, a tear portion or panel is torn from the container to form an opening. The tearing of the sheet ma terial leaves a relatively sharp edge on the removed panel and also leaves a relatively sharp edge on the rim of the opening. These sharp edges are potential sources of danger to the consumer particularly if the container or removed panel is carelessly handled.

This problem is particularly acute in the so-called full panel pullout in which the removed panel covers a major area of the can end. These full panel pullout ends are often used on a food product such as pudding, some of which may adhere to the inner or non-public side of the panel. When this occurs, the consumer may lick the inner surface of the removed panel and by so doing may cut his tongue. This of course is only one example of how one of the sharp edges on the panel can produce injury.

In our earlier copending application, this problem is solved by a protector or guard on the tear portion which extends along the periphery of the tear portion. The guard provides a relatively dull surface adjacent the sharp edge which shields the user from the sharp edge.

In one form, the guard includes multiple layers of sheet material formed integrally with the tear portion. Although the guard very adequately solves the injury problem, it introduces two additional problems. First, the guard inhibits the initiation of severance of the sheet material along the line of weakness. Specifically, easy opening container walls of this type are typically opened by depressing a peripheral segment of the tear portion inwardly. The guard, which may be in the form of a relatively stiff guard bead on the inner side of the tear portion, resists inward movement of the peripheral segment. Therefore, the initial pop is more difficult to obtain.

Following the initial pop, a paddle section of the tear portion is bent inwardly, usually about a bend zone, to rupture a segment of the sheet material along the line of weakness. This inward bending of the paddle section is typically brought about by pivotal movement of the opening tab.

Following such pivotal movement of the tab, the user pulls outwardly on the tab to pull out the panel from the container wall. The guard, however, has an edge which lies radially outwardly of the line of weakness. This edge tends to hang up during the initial pull on the tab so that the initial portion of the pulling phase of the opening operation is made more difficult.

SUMMARY OF THE INVENTION The present invention facilitates the initial severance or pop of the sheet material at the line of weakness by interrupting the guard at the peripheral segment of tear portion which is depressed inwardly. Interruption of the guard could be a simple absence of the guard at the peripheral segment. However, this would mean a loss of protection at the peripheral segment. Accordingly, a better form of interruption is an appropriate discontinuity of the guard without completely eliminating it.

In one preferred form of the invention, the guard includes a guard bead located axially inwardly of the line of weakness. With this construction, the guard is interrupted at the peripheral segment by spacing the guard bead axially inwardly from the peripheral segment to thereby allow the peripheral segment to be forced inwardly to initiate rupture of the sheet material without substantial interference from the guard bead. Another advantage of this construction is that when the peripheral segment is forced inwardly, it is deformed into substantial contact with the guard bead. Accordingly, the guard bead, once the tear portion is removed, is fully effective, even at the peripheral segment, to protect the user against injury.

The present invention also facilitates the initial pull phase of the tear portion removal operation. The guard has an edge on the inner or nonpublic side of the container wall which extends generally along the line of weakness. The edge of the guard lies radially outwardly of the line of weakness along a major portion of the line of weakness to thereby provide maximum protection against injury from the sharp edge. However, the edge lies slightly radially inwardly adjacent the portions of the line of weakness which are ruptured by the initial pull on the tab. As the edge lies radially inwardly of these portions of the line of weakness, it cannot increase the resistance to the initial pull of the tab. Al-

though the edge may lie slightly radially outwardly of a major portion of the line of weakness, it has been found that this does not create any significant resistance to the pulling phase of the removal operation after the initial pull is accomplished The present invention also provides a novel and advantageous method of making a double fold in sheet material. This method can be used to particular advantage in constructing a preferred form of the easy opening container wall of this invention.

According to the method of this invention, a piece of sheet material is provided with the sheet material having first and second axially offset radial sections integrally joined by a generally axial wall. The second radial section has an expansion rib formed integrally therewith adjacent the axial wall.

Next axially directed compressive forces are applied to the expansion rib to completely flatten the rib. Flattening of the rib results in the application of a radial outward force to the adjacent end of the axial wall. The effect of collapsing the expansion rib is to incline the axial wall in a known direction so that when axial compressive forces are applied to the two radial sections a double fold will be provided. As this double fold or pair of reverse bends is of the type which can be used to form a guard-for the easy opening container wall of this invention, this method is particularly adapted for use in making the preferred form of the easy opening container wall.

Another feature of the method of this invention is the manner in which the guard bead is caused to be spaced from the peripheral segment of the tear portion which is first ruptured by the tab. This can be advantageously accomplished by providing a space into which the guard can move during the work operation which results in the formation of the guard.

The invention can best be understood by reference to the following description taken in connection with the accompanying illustrative drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plan view of an easy opening container having a protector to protect the user against injury from the sharp edge of the tear portion.

FIG. 2 is an enlarged fragmentary sectional view taken generally along line 22 of FIG. 1.

FIG. 3 is a fragmentary sectional view of the container with the panel removed.

FIGS. 4 and 5 are enlarged fragmentary sectional views taken generally along lines 4-4 and 55, respectively, of FIG. 1.

FIG. 6 is a schematic plan view of the container wall with the tab removed showing the relationship between the peripheral edge of the guard and the score line.

FIG. 7 is a top plan view of a can end blank.

FIG. 8 is a fragmentary sectional view taken along line 8- 8 of FIG. 7.

FIG. 9 is a sectional view taken on an axial plane and illustrating the tooling for forming a dimple and for coining the connecting wall.

FIG. 10 is a sectional view taken on an axial plane showing the tooling for converting the dimple into a hollow rivet and for formation of the rib.

FIG. 11 is a sectional view taken on an axial plane and illustrating the tooling for initiating axial collapse of the rib and axial compression of the radial sections.

FIG. 12 is an enlarged fragmentary sectional view taken on an axial plane illustrating the axial compression of the container wall to form two reverse bend sections.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIGS. 1-5 illustrate an easy opening container 11 in the form of an easy opening can. The container 11 includes a generally cylindrical peripheral wall 13 of sheet material, the upper end of which is closed by an easy opening container or end wall 15 which is attached to the upper end of the peripheral wall by interlocking

flanges

17 and 19. The lower end or bottom of the peripheral wall 13 can be closed in any conventional manner such as by an end wall intregral therewith or by an end wall which is attached to the lower end of the peripheral wall in a conventional manner.

The peripheral wall 13 may be of conventional construction except for an annular rib 21 which projects radially inwardly closely adjacent and beneath the wall 15.

The easy opening container wall 15 is constructed of sheet material such as aluminum or an aluminum alloy. The easy opening container wall 15 has a line weakness in the form of a score line 23 which defines a relatively large panel or tear portion 25 which can be removed from the container 11. The panel 25 covers a major portion of the area of the container wall 15 and has an inner or non-public surface 26. The configuration of the score line 23 is described in connection with FIGS. 4-6. An annular coined region 26a of reduced thickness extends along the score line 23.

A tab 27 is attached to the panel 25 in any suitable manner such as by a hollow rivet 29. Although the tab 27 could be of various constructions, in the embodiment illustrated, it is of the type disclosed in common assignees copending application Ser. No. 64,291. The tab 27 is integrally constructed from a single piece of sheet metal and generally includes a tab body or lever 31 and an attaching portion or ear 33 which is connected to the tab body 31 by a connecting wall 35. The rivet 29 projects through the attaching ear 33 to attach the tab 27 to the panel 25. The tab body 31 has a lifting end 37 and a rupturing flange 39 at opposite ends thereof.

The tab body 31 has an outer reinforcing curl 43 which extends substantially completely around the tab body except for the rupturing flange 39. Adjacent the connecting wall 35, the curl 43 has legs 45 and 47 connected by a bend portion 49 which the latter being engageable with the connecting wall 35. The bend portion 49 is round and acts to support the connecting wall during manipulation of the tab.

An outer or marginal region of the panel 25 has the sheet material thereof bent to form an outwardly opening reverse bend portion 51 and an inwardly opening reverse bend portion 53. The bend portion 53 has a smooth dull surface or outer peripheral edge 55 which lies adjacent the score line 23. As shown in FIG. 2, the reverse bends 51 and 53 are joined to the score line 23 and to the panel 25, respectively. The reverse bends 51 and 53 are interconnected by a connecting leg 57 which forms an intermediate layer of the marginal portion of the panel 25. As shown in FIG. 2, the reverse bend 53 lies axially inwardly of the score line 23.

More specifically, a marginal region of the panel 25 is bent to form an upper layer 56 of sheet material, a

lower layer 56a of sheet material and the intermediate layer or connecting wall 57. All of the

layers

56, 56a, and 57 are annular and extend continuously around the marginal portion of the panel 25. The

layers

56, 56a and 57 and the

bends

51 and 53 form a guard bead. At all locations along the score line 23 except for the region adjacent the rupturing flange 39 (FIG. 2) the

layers

56, 56a and 57 are substantially parallel, and the

layers

56 and 56a are flattened against the intermediate layer 57, as shown in FIG. 4. With this construction, the intermediate layer 57 abuts the upper layer 56 over substantially the full length of the intermediate layer.

However, at the region of the score line 23 adjacent the rupturing flange 39, the intermediate layer 57 is not bent into tight supporting engagement with the upper layer 56. Rather, as shown in FIG. 2, the intermediate layer 57 projects radially outwardly and axially inwardly in extending from the bend 51 to the bend 53. With this construction, the intermediate layer 56 is not backed up or supported immediately axially inwardly of the score line 23. This facilitates the initiation of severance of the sheet material along the score line 23, i.e., the initial pop.

When the lifting end 37 of the tab 27 is raised, the connecting wall 35 of the tab readily bends to allow the tab body 31 to pivot relative to the attaching ear 33. This forces the rupturing flange 39 against the sheet material at a region of the score line 23 and tends to force a peripheral segment of the layer 56 so engaged by the rupturing flange 39 axially inwardly. If the intermediate layer 57 were in tight engagement with the inner face of the layer 56, it would support the latter,

and therefore resist the inwardly directed force applied by the rupturing flange 39. However, with this invention, the

layers

56a and 57 are spaced axially at the region axially inwardly of the rupturing flange 39 so that the layer 56 is unsupported in this region. Accordingly, the region of the score line 23 engaged by the rupturing flange 39 is ruptured with about the same ease as though the guard bead were not provided.

Upon continued pivotal movement of the tab body 31, the tearing of the sheet material along the score line 23 continues to thereby rupture a segment of the line of weakness. Such pivotal movement of th tab body 31 also bends a paddle section 58 of the panel inwardly into the container 11 to form an opening 58a (FIG. 3). The inward pressure applied to the layer 56 by the flange 39 may tend to bend the layer 56 into engagement with the layer 57 as shown in phantom lines in FIG. 2. The tab 57 is then pulled outwardly to rupture the remainder of the sheet material along the score line 23 thereby removing the panel 25 from the container 11.

The rupture of the sheet material forms a relatively sharp edge 59 on th panel 25 as shown in dashed lines in FIG. 2 and a relatively sharp edge 60 on the container (FIG. 3). The dull surface or edge 55 preferably lies closely adjacent the sharpedge 59 to form a shield or partial sheath therefor. In addition, the edge of the panel 25 is thick because it is defined by the three layers of

sheet material

56, 56a and 57. These two factors combine to make it extremely difficult to be injured by the sharp edge 59.

The rib 21 on the peripheral wall 13 preferably projects radially inwardly so that the edge 55 of the paddel section 58 just clears the rib 21 as the paddle section is bent inwardly of the container 11. As shown in FIG. 3, the rib 21 projects radially inwardly through a location which is in substantial alignment with the sharp edge 60. Thus, the rib 21 serves as a guard to make cutting contact with the sharp edge 60 much more difficult.

To facilitate the initial pull of the tab 27, the present invention provides certain relationships between the edge 55 and the score line 23. With reference to FIG. 6, pivotal movement of the tab body 31 bends the paddle section 58 inwardly about a bend zone or line 58b. Although the bend line 58b is shown as a straight line in FIGS. 1 and 6, obviously it may have other configurations. This results in tearing of a segment of the score line 23 lying

intermediate points

580 and 58d which define the ends of such segment and the ends of the bend line 58b.

The present invention orients the edge 55 and the score line 23 in such a way as to achieve maximum protection from injury and to facilitate the initial pull of the tab 27. To obtain maximum protection, the edge 55 preferably lies slightly radially outwardly of the score line 23 so that it can better protect the user against injury from the sharp edge 59. On the other hand, it has been found that if the edge 55 lies radially outwardly of the score line 23 adjacent the

points

580 and 58d, the edge 55 tends to hang up on the rim of the opening 58a (FIG. 3). Accordingly, this invention provides for locating the edge 55 radially outwardly of the score line 23 along substantially all of the score line except for the regions of the score line adjacent the points 58c and 58d.

A preferred way of configuring and positioning the score line 23 and the edge 55 is shown in FIG. 6. The edge 55 is circular in plan. The score line 23 contains a circular portion 23a which is concentric with the edge 55. The circular portion 23a is a major portion of the score line 23 and, in the form shown in FIG. 6, extends for approximately 270 of the score line. Obviously, the circular portion 23 may extend through arcs other than 270.

The score line 23 also includes a pair of arcuate sections 23b and 23c which, in the embodiment illustrated, extend through the same number of degrees and have radii of identical lengths. The radii of the arcs 23b and 230 are smaller than the radius of the circular portion 23a, and for this reason each of the arcs 23b and 230 forms a hump on the score line 23. The circular portion 23a terminates at reference lines XX and YY. The arcs 23b and 230 intersect at reference line ZZ, which is a radial line along which the rupturing flange 39 engages the score line 23, and terminate at lines YY and XX, respectively.

With this construction, the edge 55 lies slightly radially outwardly of the circular portion 23a as shown in FIGS. 4 and 6. At and adjacent the points 58c and 58d,- the edge 55 lies slightly radially inwardly of the score line as shown in FIG. 5. At and adjacent the rupturing flange 39 (reference line Z-Z in FIG. 6) the edge 55 lies radially outwardly of the score line 23 as shown in FIGS. 2 and 6. The location of the

points

580 and 58d may vary depending upon the manner in which the tab body 31 is manipulated. Accordingly, it is preferred to have the edge 55 lie radially inwardly of the score line 23 along regions of sufficient length to accommodate all reasonable variations in locations of the

points

580 and 58d.

In FIG. 6, the humps formed by the arcs 23b and 23c have been exaggerated for clarity. In actual practice, the score line 23 may appear to be substantially circular in plan. In the embodiment illustrated, the arcs 23a, 23b and 230 have centers C1, C2, and C3, respectively.

With the construction shown diagrammatically in FIG. 6, the edge 55 lies radially inwardly of the score line 23 and hence from the edge 60 (FIG. 3) at the

points

580 and 58d. Accordingly, the edge 55 cannot hinder removal of the tear portion 25. The edge cannot even where located radially inwardly of the score line 23 is sufficiently close to the sharp edge 59 to afford substantial protection. In addition, tongue injuries of the type described hereinabove are less likely to be caused on the paddle section 58 because this portion is bent and not as easy to lick.

FIGS. 7-12 illustrate a preferred method of constructing the easy opening container wall 15 shown in FIGS. 1-6. FIGS. 7 and 8 show a can end blank 61. The blank 61 includes a peripheral attaching flange 63, an axial wall 65 and a pair of radial walls or

sections

67 and 69 which are axially offset and interconnected by a generally axial or connecting wall 71. In the embodiment illustrated, the section 67 and the wall 71 are annular, and the section 69 is circular. The blank 61 may be formed into this configuration with any suitable tooling.

FIG. 9 shows a first work operation in which a dimple 73 is formed and in which the connecting wall 71 is coined to elongate the same. In FIG. 9, the connecting wall 71 is squeezed between a lower coining die 75 and an upper coining die 77 with the compressive force being sufficient to cause thinning and consequent generally axial elongation of the connecting wall 71. The elongation of the connecting wall 71 facilitates formation of the reverse bends 51 and 53. Specifically, the dies 75 and 77 have coining surfaces 79 and 81, respectively, which coin the sheet material between reference lines AA and B-B. The lower coining die 75 also has horizontal supporting

surfaces

83 and 85 for supporting the radial section 67 and an annular region 87 which extends between the connecting wall 71 and the dimple 73. The tooling provides

spaces

88 and 88a to accommodate the elongation of the connecting wall 71.

The dimple 73 is formed by a punch 89 and a cooperating die 91. The punch 89 engages the sheet material of the section 69 and offsets a zone of the same into a die cavity 93. Ultimately the offset sheet material is engaged between the cooperating surfaces of the punch 89 and the die 91 to coin the sloping wall of the dimple. The coined regions are generally those portions of the dimple 73 which are shown in FIG. 9 as being compressively engaged. A dimple making process which involves stretching and coining of the sheet material is disclosed in common assignees U.S. Pat. No. 3,638,597. The annular region 87 is not coined during the work operation illustrated in FIG. 9.

In the work operation shown in FIG. 10, the dimple 73 is converted into a hollow rivet 95 and the connecting wall 71 is converted into a shorter connecting wall or axial wall 97 and an annular expansion rib 99 which lies between the wall 97 and the rivet 95. The wall 97 extends substantially axially whereas the connecting wall 71 (FIG. 9) is inclined or sloped relative to the axis of the blank 61. The annular expansion rib 99 is closely adjacent the wall 97.

The dimple 73 is converted into the rivet 95 by a rivet punch 101 and a rivet die 103. An outer annular region of the dimple 73 is collapsed and flattened between working faces 105 and 107 of the punch 101 and the die 103, respectively. The punch 101 has a head 109 which is within the rivet 95 to assist the formation thereof, and the rivet 95 is in a die cavity 111.

The expansion rib 99 is formed by stretching and deformation of the sheet material of the connecting wall 71 by a punch 113 and a die 115. The punch 113 has a head 117 which engages the sheet material and forces the same into a die cavity 119.

The wall 97 is formed from the upper'regions of the connecting wall 71. This is accomplished by the punch 113, the die and a tool 121. In addition, the die 115 cooperates with the tool 121 to bend the sheet material at the juncture of the section 67 and the wall 97 so that the wall 97 extends in a substantially axial direction.

In the work operation shown in FIG. 11, the score line 23 is formed and an axial compressive force is applied to the expansion rib 99 by a pair of

compression tools

125 and 127 to completely flatten the expansion rib. The scoring operation can advantageously be carried out by a scoring die 129 and by a tool 131 which supports the section 67. A spring 130 urges the die 129 and the tool 127 in opposite directions. In addition, a punch is partially inserted into the rivet 95.

The tool 127 and the die 129 are advanced relative to the

tools

125 and 131. The tool 127 strikes the upper end of the expansion rib 99 to initiate axial collapse and radial expansion thereof. Radial expansion of the expansion rib 99 moves the lower end of the axial wall 97 radially outwardly with the wall 97 pivoting about regions 132. This creates a generally Z-shaped cross section with the wall 97 extending both axially and radially. In addition, as the scoring tool 129 is relatively advanced, it applies an axial compressive force to the

radial sections

67 and 69 with the result that the wall 97 becomes more inclined relative to the axis of the blank 61 in the manner shown in FIG. 7. The expansion rib 99 is completely collapsed in the work operation of FIG. 11.

During the operation shown in FIG. 11, the sheet material adjacent the ultimately formed score line 23 is confined by the tool 131 and the scoring die 129. As the die 129 and the tool 131 relatively advance, the sheet material between the die 129 and the tool 131 is compressively engaged to hold the section 67 in position and to form the score line 23. At the end of the stroke the sheet material radially outwardly of the score line23 is coined by a coining face 132a, and this further tends to hold the section 67 in positin during the last bit of radial expansion of the expansion rib in the operation of FIG. 11. Ordinarily, the material radially inwardly of a point X will be thinner than the material radially outwardly of the score line 23 as a result of the coining operation of FIG. 9, and consequently the face 132a will not ordinarily coin the material radially inwardly of the score line.

By confining and compressively engaging the sheet material adjacent and along the score line 23 to prevent movement thereof, stresses of the type which might create tiny cracks or openings in the sheet material along the score line are less likely to occur. In addition, slight coining adjacent the score line 23 is believed beneficial to the characteristics of the sheet material along the score line.

FIG. 12 illustrates the next work operation in which the

radial sections

67 and 69 are moved toward each other with consequent collapse of the wall 97 to form

reverse bend sections

51 and 53 substantially as shown in FIG. 2. During the work operation of FIG. 12, the blank 61 is retained between tools or workholders 137 and 139, and the punch 141 is received within the rivet.

A compression tool 143 is moved upwardly and cooperates with the tool 139 to at least partially collapse the wall 97 (FIG. 11) to thereby form the reverse bends 51 and 53. Specifically, the compression tool 143 has an annular working face 147 which is continuous and planar except for a peripheral segment of the tool 143 at which a radial shoulder 149 and an axial shoulder 151 cooperate to define a recess 153. The recess 153 is formed at the periphery of the tool 143 and extends circumferentially for a very short distance.

The recess 153 increases the spacing between the

tools

139 and 143 over what it would be without the recess. Accordingly, the sheet material is not compressed as much by the

tools

139 and 143 at the recess 153 as it is where the recess does not exist.

SPecifically, the

tools

139 and 143 squeeze and completely collapse the wall 97 to form the configuration shown in FIG. 4 at all locations which do not confront the recess 153. This squeezing action of the

tools

139 and 143 converts the regions 132 (FIG. 11) into the

bends

51 and 53, respectively, and the wall 97 (FIG. 11) into the intermediate layer 57 as shown in our copending application referenced hereinabove.

At the recess 153, the greater spacing between the

tools

139 and 143 makes it possible for the

layers

56, 56a, and 57 not to be folded tightly against each other. At the beginning of the work operation of FIG. 12, the layer 56 is supported from above by a flat annular working face 156 of the tool 139, and the layer 56a is unsupported from below. Accordingly, the relative advance of the

tools

139 and 143 forces the unsupported layer 56a into the recess until the bend 53 engages the shoulder 149. This prevents the intermediate layer 57 from being bent up tight against the upper layer 56. This leaves a space 155 between the

layers

56 and 57 along the circumferential length of the recess 153 as shown in FIG. 12. Thus, the circumferential dimension of the recess 153 should be selected in accordance with the desired circumferential dimension of the cross section shown in FIG. 12, Le, the circumferential dimension of the interruption of the guard bead. The tool 143 also cooperates with a pressure pad 157.

Some ofthe material of the connection wall 71 (FIG.-

8) is used to form the reverse bends 51 and 53. Because the connecting wall 71 has been thinned, the reverse bends 51 and 53 are more easily formed and are less likely to have cracks.

Following the work operation of FIG. 12, the tab 27 (FIGS. 1 and 2) can be attached to the blank 61 by heading of the rivet 95 to thereby convert the latter into the rivet 29 (FIGS. 1 and 2). Thereafter, the resulting easy opening container wall can be attached to the container 11 as shown in FIG. 2.

Although the method shown in FIGS. 7-l2 is particularly adapted for making an easy opening container wall of the type shown in FIG. 2, it may be used in other instances where it is desired to form a double fold or double reverse bend sections.

Although exemplary embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art wihtout necessarily departing from the spirit and scope of this invention.

We claim: 1. An easy opening container wall comprising: a container wall of sheet material; a line of weakness in the container wall defining a tear portion at least partially removable therefrom;

first means attached to said tear portion for initiating rupture of the sheet material by an inwardly directed force and for tearing the sheet material generally along the line of weakness to at least partially remove the tear portion from the container wall, said tearing of sheet material providing a relatively sharp edge on the tear portion, the initiation of rupture of the sheet material occurring at a preselected region along the line of weakness;

second means on the tear portion and extending along a peripheral region thereof for protecting the user against injury from the sharp edge when the tear portion is at least partially removed from the container wall; and

said second means being interrupted adjacent said preselected region of the line of weakness sufficiently to substantially prevent said second means from hindering the initiation of rupture of the sheet material in response to said inwardly directed force.

2. An easy opening container wall as defined in claim 1 wherein said first means includes a tab at least a portion of which is pivotable to rupture the sheet material at said preselected region and along a segment of the line of weakness, said second means lying radially inwardly of said line of weakness at the ends of said segment.

3. An easy opening container wall comprising:

a container wall of sheet material;

a line of weakness in the container wall defining a rupturable web; said rupturable web defining a tear portion at least partially removable therefrom;

means attached to said tear portion for initiating rupture of the rupturable web at a preselected region thereof by an inwardly directed force and for tearing the rupturable web to at least partially remove the tear portion from the container wall, said tearing of the 'sheet material providing a relatively sharp edge on the tear portion;

a guard on the inner side of said tear portion extending along the periphery of the tear portion to protect the user against injury from the sharp edge; and

said guard being spaced inwardly in a generally axial direction from the rupturable web at least adjacent a portion of said preselected region tofacilitate the initiation of rupture of the rupturable web at said preselected region by said inwardly directed force.

4. An easy opening container wall as defined in claim 3 wherein said guard includes multiple layers of sheet material of the tear portion.

5. An easy opening container wall as defined in claim 3 wherein said guard includes a guard bead.

6. An easy opening container wall comprising:

a container wall of sheet material;

a line of weakness in the container wall defining a tear portion at least partially removable therefrom;

means attached to said tear portion for tearing the sheet material generally along said line of weakness to at least partially remove the tear portion from the container wall, said means initiating rupture of the line of weakness by forcing a peripheral segment of the tear portion inwardly;

said tear portion including a panel portion having and a marginal region substantially circumscribing said panel section; reverse bend section joined to said panel section and opening generally radially inwardly,

the marginal region of said tear portionhaving a cross sectional configuration which includes a first reverse bend section opening generally radially outwardly, a second generally radially inwardly, and a leg section joining said bend sections;

said second reverse bend section being in a radial position closely adjacent the line of weakness to shield the user against injury from the sharp edge;

said second reverse bend section and at least a portion of said leg section being spaced generally axially inwardly from at least a portion of said peripheral segment to allow said peripheral segment to be forced inwardly to initiate rupture of the line of weakness without substantial interference form the bend sections and said leg section.

7. An easy opening container wall as defined in claim 6 wherein said tearing of the sheet material provides a relatively sharp edge on the tear portion, said bend sections and said leg section at least partially define a protector for protecting the user against said sharp edge, and said initiation of rupture deforms said peripheral segment inwardly into substantial contact with said leg section whereby the protector can more efficiently protect the user against injury from the portion of said sharp edge of the peripheral segment.

8. An easy opening container wall comprising: a container wall of sheet material having an inner side; a line of weakness in the container wall defining a tear portion at least partially removable therefrom;

first means attached to said tear portion for tearing the sheet material generally along said line of weakness to at least partially remove the tear portion from the container wall, said tearing of the sheet material providing a relatively sharp edge on the tear portion;

said first means including means for forcing a paddle section of the tear portion inwardly to rupture the sheet material along a segment of the line of weakness;

second means on said tear portion for protecting the user against injury from the sharp edge;

said second means including an outer peripheral edge on the inner side of said container wall extending generally along the line of weakness; and

said edge lying radially inwardly of the line of weakness adjacent the ends of said segment and radially outwardly of the line of weakness along a major portion of the line of weakness.

9. An easy opening container wall as defined in claim 8 wherein said edge is circular in plan and said line of weakness is noncircular.

10. An easy opening container wall as defined in claim 9 wherein said major portion of the line of weakness forms a part of a circle which is substantially concentric with the circular edge.

11. An easy opening container wall as defined in claim 10 wherein the portion of said edge which lies radially inwardly of the line of weakness includes first and second arcs, each of said arcs forming a portion of a circle and being nonconcentric with each other and with said major portion of the line of weakness.

12. An easy opening container wall as defined in claim 8 wherein said second means is interrupted along at least a portion of said segment.

13. An easy opening container wall as defined in claim 8 wherein said second means includes a guard bead, said edge being on said guard head.

14. An easy opening container wall as defined in claim 13 wherein said guard bead has a cross sectional configuration which includes a first reverse bend section opening generally radially outwardly, a second reverse bend section joined to said panel section and opening generally radially inwardly, and a leg section joining said bend sections, said edge being a peripheral surface of the second reverse bend section.

15. An easy opening container wall comprising:

a container wall of sheet material;

means forming a line of weakness in the container wall defining a tear portion that is completely removable from said container wall;

means attached to said tear portion for rupturing the sheet material by forcing a paddle section of the tear portion inwardly to rupture the sheet material along a segment of the line of weakness;

means integral with said tear portion for protecting the user against injury from the sharp edge formed after severance thereof;

said-integral means being of generally circular shape in plan view, and

said line of weakness being concentric with respect to a portion of said integral means and including a portion in the region of said paddle which is not concentric with said integral means.

16. An easy opening container wall as set forth in claim 15 wherein integral means includes a rounded edge defining, in the region of concentricity with said line of weakness, a diameter in plan view somewhat greater than that of the circle formed by said line of weakness.

17. An easy opening container wall as set forth in claim 16 wherein said rounded edge 5 located vertically below the plane of the line of weakness whereby upon removal of the tear portion the rounded edge extends beyond the sharp edge in the portion thereof concentric with the sharp edge.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3,837,524 Dated Sept. 24, 1974 Inventor(s) James R. Schubert and Omar L. Brown It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 10, line 44, after "panel" delete "portion having" and insert section-;

Column 10, line 46, after "section; delete remainder of line;

Column 10, delete lines 47 and 48;

Column 10, line 52, after "second" insert reverse bend section joined to said panel section and opening-;

Column 10, line 57, change "an" to -and.

Colunm 12, line 40, after "edge" change "s" to is-.

Assignee: Ermal C. Fraze, Dayton, Ohio Signed and Scaled this twenty-seventh D3) of April 1976 [SEAL] A lies I:

RUTH C. MASON C. MARSHALL DANN Arresting Officer (mnmissium'r uj'lalents and Trademarks

Claims

1. An easy opening container wall comprising: a container wall of sheet material; a line of weakness in the container wall defining a tear portion at least partially removable therefrom; first means attached to said tear portion for initiating rupture of the sheet material by an inwardly directed force and for tearing the sheet material generally along the line of weakness to at least partially remove the tear portion from the container wall, said tearing of sheet material providing a relatively sharp edge on the tear portion, the initiation of rupture of the sheet material occurring at a preselected region along the line of weakness; second means on the tear portion and extending along a peripheral region thereof for protecting the user against injury from the sharp edge when the tear portion is at least partially removed from the container wall; and said second means being interrupted adjacent said preselected region of the line of weakness sufficiently to substantially prevent said second means from hindering the initiation of rupture of the sheet material in response to said inwardly directed force.

3. An easy opening container wall comprising: a container wall of sheet material; a line of weakness in the container wall defining a rupturable web; said rupturable web defining a tear portion at least partially removable therefrom; means attached to said tear portion for initiating rupture of the rupturable web at a preselected region thereof by an inwardly directed force and for tearing the rupturable web to at least partially remove the tear portion from the container wall, said tearing of the sheet material providing a relatively sharp edge on the tear portion; a guard on the inner side of said tear portion extending along the periphery of the tear portion to protect the user against injury from the sharp edge; and said guard being spaced inwardly in a generally axial direction from the rupturable web at least adjacent a portion of said preselected region to facilitate the initiation of rupture of the rupturable web at said preselected region by said inwardly directed force.

6. An easy opening container wall comprising: a container wall of sheet material; a line of weakness in the container wall defining a tear portion at least partially removable therefrom; means attached to said tear portion for tearing the sheet material generally along said line of weakness to at least partially remove the tear portion from the container wall, said means initiating rupture of the line of weakness by forcing a peripheral segment of the tear portion inwardly; said tear portion including a panel portion having and a marginal region substantially circumscribing said panel section; reverse bend section joined to said panel section and opening generally radially inwardly, the marginal region of said tear portionhaving a cross sectional configuration which includes a first reverse bend section opening generally radially outwardly, a second generally radially inwardly, and a leg section joining said bend sections; said second reverse bend section being in a radial position closely adjacent the line of weakness to shield the user against injury from the sharp edge; an said second reverse bend section and at least a portion of said leg section being spaced generally axially inwardly from at least a portion of said peripheral segment to allow said peripheral segment to be forced inwardly to initiate rupture of the line of weakness without substantial interference form the bend sections and said leg section.

8. An easy opening container wall comprising: a container wall of sheet material having an inner side; a line of weakness in the container wall defining a tear portion at least partially removable therefrom; first means attached to said tear portion for tearing the sheet material generally along said line of weakness to at least partially remove the tear portion from the container wall, said tearing of the sheet material providing a relatively sharp edge on the tear portion; said first means including means for forcing a paddle section of the teaR portion inwardly to rupture the sheet material along a segment of the line of weakness; second means on said tear portion for protecting the user against injury from the sharp edge; said second means including an outer peripheral edge on the inner side of said container wall extending generally along the line of weakness; and said edge lying radially inwardly of the line of weakness adjacent the ends of said segment and radially outwardly of the line of weakness along a major portion of the line of weakness.

13. An easy opening container wall as defined in claim 8 wherein said second means includes a guard bead, said edge being on said guard bead.

15. An easy opening container wall comprising: a container wall of sheet material; means forming a line of weakness in the container wall defining a tear portion that is completely removable from said container wall; means attached to said tear portion for rupturing the sheet material by forcing a paddle section of the tear portion inwardly to rupture the sheet material along a segment of the line of weakness; means integral with said tear portion for protecting the user against injury from the sharp edge formed after severance thereof; said integral means being of generally circular shape in plan view, and said line of weakness being concentric with respect to a portion of said integral means and including a portion in the region of said paddle which is not concentric with said integral means.

17. An easy opening container wall as set forth in claim 16 wherein said rounded edge s located vertically below the plane of the line of weakness whereby upon removal of the tear portion the rounded edge extends beyond the sharp edge in the portion thereof concentric with the sharp edge.