JPH0773766B2 - Can shell - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metal shell for a can used for forming an end portion of a can type container.

[0002]

2. Description of the Related Art For example, most can-shaped containers such as beer cans and soft drink cans have internal pressure, rough handling,
It is necessary to be able to withstand considerable temperature changes and to be able to maintain a perfect hermetic seal and protect the contents of the can. The above types of cans are used in large quantities of billions a year, and most of the metals currently used to make cans are aluminum, which is lightweight, relatively inexpensive, and easy to process. Has become.

[0003] Today's common cans include a deep-drawing single body, usually with a narrow middle throat, at the upper end leading to the outwardly extending body curl, and an open can or tab. It consists of a can end with a shell (the invention relates to this shell) which is a self-opening structure provided with associated cut lines and the like. The shell cuts a suitable blank from a sheet of thin metal and molds the blank to form a central panel surrounded by a reinforcing recess and a chuck wall, which is then placed in a seaming machine. Manufactured by interacting with the curl to form a shell curl that allows the end to be attached to the can in the requisite hermetic seal. In most cases, the underside or curl end of the shell is coated with a sealant admixture and is configured to aid in molding the shell.

The shell is the basic component of the can,
Manufactured from blanks. The shell is then processed in the secondary processing equipment to form the desired score line, open can tab and integral joint between shell and open can tab. These are all performed by known methods. The hermetic admixture can be applied to the bottom or bottom of the shell either before or after secondary processing (generally before processing).

[0005]

One of the main efforts of the engineers involved in the manufacture of the can end is to reduce the material and to make the material as thin as possible in order to save considerable costs. The use is to manufacture cans. However, there is a limit to molding the shell by using an extremely thin metal material in order to maintain the integrity of the shell and particularly to secure the strength capable of withstanding the internal pressure. Generally, to make the thin metal plate able to withstand the drawing and machining operations performed on the blank during the shell forming process, the reinforcing structure is formed by using a metal plate that is somewhat thicker. It is necessary to be able to cope with the partial thinning of shell when doing.

In prior art shell forming operations, a blank is cut from a thin sheet of metal, typically steel or aluminum, and then formed into a generally flat central panel and upwards from this central panel during this primary processing stage. With a chuck wall extending outwardly towards the curved flange portion. In one prior art method, the blank is formed with a groove around the central panel inside the chuck wall. This blank is then curl bent to form curl edges on the flange. The curled edge is bent somewhat upward at the flange portion.

The partially molded shell, after curling, is sent to another tool where the flange portion is gripped and the curl bending edge is protected in the tool from deformation. If the blank is already provided with a groove, then the groove is corrected. In the absence of the groove, the blank, fixed as described above, is moved against the fixed bearing forces acting on the main part of the central panel.

The shell comprises an unsupported portion including an edge of the central panel that overlies the fixed support and extends beyond the support to the portion where a portion of the chuck wall is secured. This crushing action compresses the blank to reshape the unsupported metal zone between the chuck wall and the center panel, resulting in a shape that forms a reinforcing groove or recess extending into the bottom of the chuck wall and the periphery of the center panel. . For this reason, the shell forming work according to the prior art requires three steps, and forming the reinforcing groove-shaped body on the shell by the above-mentioned method is almost unprocessed between the chuck wall and the central panel. The metal blank zone is to be machined, so that the most important parts of the structure are subject to cracking, deformation or shell thinning.

In addition, prior art shells may have protrusions on the peripheral flange and curled edge portions known as "earrings" in the industry. Usually, when cutting a metal blank from a feed material, which is a thin sheet drawn from a roll, conventional methods cut a rounded blank, paying little attention to the direction of the crystals through the longitudinal direction of the sheet. When forming a metal (particularly a thin aluminum plate) at the time of manufacturing a circular shell, the metal tends to be slightly stretched in the crystal direction rather than in the direction perpendicular to the crystal, and further, at an angle of 45 ° with respect to the crystal. It has not been solved, although it has been known for some time that the first-order circular blanks are somewhat deformed because they are more easily stretched in the direction. As described above, when the metal "stretches" unevenly, as a result, a slight deformation is observed at the blank edge to be curled. For this reason, the curled lower edge is in a state in which only a part thereof is somewhat closer to the chuck wall in the shell peripheral portion. That is, the curl edge is irregular with respect to the chuck wall.

Two problems result from this situation. If the enlarged "earrings" on the perimeter were manufactured to form the primary sealing means for joining the ends to the can, the curl ends of the blank between the "earrings" would be shorter, at which point the curl ends Since the metal of (2) does not fit perfectly under the curled portion of the can body, it is necessary to use a hermetic admixture to maintain a hermetic seal. When referred to as a perfect seam, it means a state in which there is no extension behind the end or the cover hook.

Alternatively, in order to achieve a hermetic seal between the ends and the body, the edges of the earrings may be completely spliced together during splicing to accommodate the expansion of the "earrings". There is a way to design it to fit well under the curl. However, in this case, in the part where the earrings are present, excess metal in the cover or the end hooks that extends into the seam remains, which results in tearing of the thin-walled can body in the narrow part, or Excessive metal wrinkles in the curl-bent seam, impairing the uniformity of the seam. Either way, after filling and sealing, the incidence of leaking cans is unacceptably high. In consideration of the loss of the packaged product and the damage caused by the leakage of the contents, it goes without saying that such a situation is unacceptable.

Accordingly, it is an object of the present invention to substantially solve the problems associated with earrings described above, and further, including the requisite chuck wall and the reinforcing panel wall joining the chuck wall and the central panel, By making the overall thickness uniform, it is possible to make the seamed portion of the final product can even better and uniform, and to facilitate the process for forming the can end. Is to provide a shell for.

A further object of the present invention is to provide a can shell having an improved peripheral curl portion.

[0014]

According to the shell for a can of the present invention, the inner edge of the curl portion is precurled,
During the seaming operation, when the shell-formed end is attached to the can, the curled portion smoothly extends into the curled and bent seamed portion, causing wrinkles in the seamed portion, and / or the can of the seamed portion. The risk of breaking or cutting the narrow portion can be minimized.

Molding the shell from a blank that is polygonal rather than circular also minimizes the occurrence of earrings and makes the curl inner diameter spaced from the shell wall of the shell more uniform and concentric. You can The blank has a shape in which the blank diameter parallel to the crystal of the thin material from which the blank is formed is smaller than the blank diameter perpendicular to the crystal direction. And, the diameters in the parallel, right angle, and 45 ° angular directions with respect to the crystal direction are different, and the transition portion of the blank side is rounded.

As a result of the primary processing of the blank by forming and drawing the blank in a controlled state and forming the shell, the blank is provided with the desired concentricity, the curl diameter is uniformly spaced from the chuck wall, and the thickness is reduced. A finished shell product of uniform thickness is obtained. As a result, the finished can has a better and more uniform seam, thereby minimizing the risk of various accidents.

The present invention also provides a finishing shell in which one or more presses, such as a standard single-acting press, are used to form the shell in two steps with only a reciprocating tool. In order to finish the desired pre-formed curl on the periphery of the shell, it is necessary to additionally perform curling and the like.

The present invention minimizes the occurrence of earrings, provides more uniform concentricity of the inner and inner curls with the chuck wall, and more particularly the wall thickness at the joint between the chuck wall and the central panel. Further provided is a can shell having an improved preformed curl formed on the periphery of the shell.

Other objects and advantages of the invention will be apparent from the claims, the following detailed description and the accompanying drawings.

[0020]

EXAMPLES In order to better understand the present invention, the following
A detailed description will be given with reference to the accompanying drawings.

The shell production according to the invention can be roughly divided into two machining operations, each of which can be carried out in a conventional single-acting ram press with a specially designed tool. A Minster P2-45 type press was used, but various other types of press can also be used.

First, a relatively thin metallic material (FIG. 3) that finally forms the shell is fed to one or more working parts in the press. Operate the press ram in each of these primary processing parts,
Separate blank B from the material and partially mold the shell from the blank.

The partially finished shells in each primary section are then transferred to corresponding secondary sections in the same press,
Then, finish molding of the shell is performed, the press is opened, and the finish shell is carried out from the press.

In a preferred embodiment of the invention, during each stroke of the single-acting press, a blank is produced in each primary part and partially finished, while in each secondary part it is partially formed. The finish of the shell is done. Further, the transfer of shells between the processing units is performed by one press stroke so that the shell partially finished in the primary processing unit is finished in the secondary processing unit by the next stroke. However, the primary and secondary parts and their corresponding tools can easily be mounted on another press, with partially finished shells from one press to another (secondary work).
It should be understood that the shells that have been rapidly transferred to or partially finished can be collected from the primary processing section and further processed by the second tool in the secondary processing section.

Blank Shape Referring to FIGS. 1 and 3, a portion S of the sheet metal from which the blank is cut is shown in FIG. The shape of the blank of the portion indicated by B is a polygon, as described later,
The whole is not an exact circle of the same diameter, but the transition from one side to the next is rounded. Referring to FIG. 1, a common end-to-can body splicing portion comprises a body hook BH and an end or cover hook CH, the overlapping portion of which is indicated by dimension OL. There is.

A quantity of hermetic admixture has been applied between the main barb and the underside of the end, which is not shown in FIG.

The effect of the earrings is to produce very slight overlaps, or to overlap too much,
In the latter case, the end or the cover hook will interfere with the bending of the seam at the seam, or it will become a crystal that breaks the wall of the can body at this seam. It has been found that the shape of the blank B can significantly reduce the influence or deformation of the earrings if properly selected with respect to the crystal of the material indicated by the arrow and symbol in FIG. For example, thin metal sheets, such as aluminum and steel, tend to "stretch" or stretch in the direction of the crystal or at 45 ° to the crystal, rather than perpendicular to the crystal.

Although the displayed numerical values are merely an example, it is possible to understand the basic idea when designing the shape of the blank according to the present invention. As shown in FIG. 3, blank B
The dimension of the horizontal axis I-I of is the maximum dimension. This is because if the blank is processed during shell formation, it will have the least elongation in this direction. For standard size blanks with standard size ends, the general size of this diameter is 75.87 mm (2.987 inch). On the other hand, the vertical diameter V--V of the blank is generally 75.692 mm (2.980 inch). The diameter III-III in each direction at 45 ° to the blank's longitudinal diameter is 75.5
4mm (2.974inch). 22.5 ° for diameter V-V
The blank diameter IV--IV in each direction is 75.743 mm (2.982 inc.
h). The diameter II−−II in each direction of 22.5 ° with respect to the horizontal axis is
It should be 75.794 mm (2.984 inch). In accordance with the present invention, 0.29 mm (0.
When manufactured from aluminum, the blank of the above shape has a rounded curl inner diameter within the range of 0.0762 to 0.127 mm and has a concentricity (described later) of 0.0762 mm with respect to the chuck wall.
A shell with almost no earrings is obtained, which is in the range of to 0.127 mm. It is to be understood that the above numbers are particularly applicable to shells of a particular size made of a particular metal and are merely an example of the invention, its basic idea and application. These numerical values do not limit the scope of the present invention.

Referring to FIG. 2, there is shown a cross section of the actual shell having the finished shape according to the present invention, which is considerably enlarged beyond the normal size. This shell is, of course, a one-piece metal product, molded from a suitable metal blank and shaped as described above. In its final finished shape, a flat center panel 10, a chuck wall 12 shaped to extend upwards and outwards relatively straight, a chuck wall 1.
Recessed portion 1 that extends upward from the inner lower edge of 2 toward the peripheral edge of the central panel 10 and surrounds the central panel 10 at the joint between the central panel 10 and the chuck wall 12.
1 and a lip body or curl edge portion 13 leading to the curl inner diameter.

Primary Working Section and Operation The press tool of each primary working section is shown in FIGS. 4 to 7. The upper tool works by being connected to the press ram, while
The lower tool is fixed to the press frame.

The lower tool is provided with a die cutting edge 14, and this cutting edge 1
From above 4, the metal material S enters the tool at a material line height approximately indicated by the line 16. The die cutting edge 14 is the die forming ring 1.
8 is firmly supported on a suitable base member. Further, the lower tool is provided with a drawing ring 24 provided between the die forming ring 18 and the die cutting edge 14. A central pressing pad 25 is concentrically provided in the molding ring 18. The throttle ring 24 is supported by a spring (not shown) mounted in the base member. This spring is compressed when the tool is closed and by the pressure exerted on the throttle ring 24.
The center pressing pad 25 is also supported by a spring (not shown) that is compressed by the acting force of the upper tool.

When the tool is opened, the drawing ring 24 and the center pressing pad 25 are held in the lower tool, and the drawing ring 24
Bottom of the pad touches the die cutting edge 14 and the central pressing pad 25
The bottom portion of the base contacts the molding ring 18. At this time, the upper surface of the drawing ring 24 is located slightly below the lowest shearing point of the die cutting edge 14, and the upper surface of the center press pad 25 is slightly above the drawing ring 24 and the lowest shearing point of the die cutting edge 14. It is located below.

The upper tool has a blank punch 3 positioned to cooperate with the aperture ring 24 when the tool is closed.
0 is provided. A knockout positioner 32 is provided above the die forming ring 18, and the shape of the punch center 34 cooperates with the central pressing pad 25 to fix the blank as well as to manufacture a partially finished shell. It has a suitable shape. When the press ram descends, the blank punch 30, knockout positioner 32,
And the punch center 34 is all closed on the lower tool at the same time.

The sequential operation of producing blanks from the material and partially forming the shell in the primary working section is illustrated in FIGS. 4-7. In FIG. 4, the tool is already shown partially closed. Material S enters the tool along the material line indicated at 16 and, as the press ram descends, shears the material between the die cutting edge 14 and the blank punch 30 to produce a flat blank B.

Since the blank punch 30 and the punch center 34 move simultaneously, the lower surface of the blank punch 30 extends somewhat beyond the lower surface of the punch center 34 so that the punch center 34 does not interfere with the material S during the blank punching operation. There is.

Further, the lead distance that the blank punch 30 extends from the punch center 34 is set to be equal to or less than the distance that the upper surface of the center pressing pad 25 is above the upper surface of the drawing ring 24 in the lower tool 12. As a result, the entire panel of the blank B has the punch center 34 and the center pressing pad 2.
5 and then the outermost part of the blank B before the start of the forming process, the blank punch 30 and the drawing ring 2
It is sandwiched between four. The use of central fixing means allows the blank B to be fixed in a central position within the tool during subsequent molding of the shell from the blank. By holding the blank in a central position, the blank is processed in a controlled manner to minimize the irregularity of curled lips on the outer edge of the finishing shell and to make the amount of subsequent seaming material more constant. be able to.

As the press ram continues to move downwards, the blank punch 30, the support ring 32 and the punch center 3
All four keep moving at the same time. In the position shown in FIG. 5, the blank is still blank punch 30 and aperture ring 2.
4 and the punch center 34 and the center presser pad 25
The shell forming operation is started on the die forming ring 18 while being sandwiched between the two.

Referring to FIG. 6, the punch center 34
It can be seen that for the blank B, the press ram continues to move downward while it begins to form the chuck wall 12.
Blank is no longer required, blank punch 30 and aperture ring 24
Not held between, but still held between the punch center 34 and the center press pad 25, the throttle ring 24 no longer controls shell formation. The clearance between the inner diameter of the blank punch 30 and the outer diameter of the die molding ring 18 is selected to be a value that allows the blank B to be appropriately molded by an appropriate resistance force. The inner diameter of the blank punch 30 is slightly narrowed above the curved portion 49 (enlarged for clarity). Therefore, the fourth
As can be seen by comparing FIG. 5 and FIG. 5, the resistance force acting on the outermost portion of the blank B increases immediately before the end of the press stroke. As a result, the portion of the shell 48 is squeezed more closely on the die forming ring 18, so that the curled portion of the shell 48 extends to the edge of the shell 48 without a straight line portion or a curl lacking portion.

In FIG. 7, the tool is shown closed and the bottom of the press ram abutting a suitable stop block. Upon completion of the first stage of the shell forming operation, the flat central panel 10 has reached a relatively large radius of curvature 52 and has been gently stretched so as not to overwork the material in that area. This large radius of curvature portion 52 forms the joint between the chuck wall 52 and the central panel 10, and later forms the shell recess and panel forming radius. Since the radius is relatively large, the shell has a sufficient wall thickness, while the concave portion later has a radius that does not cause a gap. From FIG. 7, a reverse chucking force acting on the inner wall of the die center forming ring 18 and the outer wall of the punch center 34 results in a straight chuck wall 12 that does not bend either inward or outward and the shell is secondary machined. It can be fitted exactly in the tool.

The shell is further provided with a lip body 53 extending generally outwardly and upwardly from the chuck wall 51, but with a generally downwardly curved portion. 2 for lip body 53
There are three other curved portions, and the cross-sectional shape of the lip body 53 is a "seagull wing" shape. The vicinity of the chuck wall 51 has a relatively slightly curved portion,
While providing the upwardly extending lip body 53, the outermost portion is provided with a relatively steep downward curve due to the die forming ring 18. However, the outer edge of the lip body 53 is positioned not above the portion where the lip body 53 is connected to the chuck wall 12 of the shell but at least flatly with the connecting portion.

When the tool is closed, the knockout positioner 32 does not contact the partially finished shell. When the molding operation is completed, the press ram is raised to release the tool, and the shell is held in the blank punch 30 by its lip body 53 being tightly fitted in the blank punch 30 and is moved upward by the upper tool. Be lifted. When the lower portion of the shell exceeds the material line height shown at 16 in FIG. 3, the knockout positioner 32 stops its lifting movement while the blank punch 30 and punch center 34 continue to rise with the press ram. When the upward movement of the knockout positioner 32 stops, the shell preform contacts the knockout positioner, which pushes the shell preform out of the still-moving blank punch 30.

The partially finished shell 48 is then held in place on the knockout positioner 32 by the vacuum pressure acting on the surface of the punch center 34 through a suitable vacuum path in the upper tool. Then, this vacuum pressure causes the shell preform to remain adsorbed on the surface of the knockout positioner 32 until it is carried out.

Upon completion of the primary processing operation for Ciel, Ciel is secondary processed by a transfer device as described in US Patent Application No. (DRT002P2) filed by the same applicant as the present application on the same date as the US application of the present application. It is transferred to a corresponding one of a plurality of tools in the section, and finish forming is performed.

Secondary Working Section Tool and Operation The secondary working section tool includes an upper tool 61 supported on a press ram and a lower tool 62 supported on a press bed, as shown in FIGS. 8 to 11. To do. The lower tool 62 includes a curl die 64 and a panel forming punch 66,
Both are fixed on a suitable base member. An insert 71 is provided in the panel forming die. A plurality of springs 74 (not shown) mounted in the base member supporting the lower tool
A spring pressing pad 72 supported by is provided concentrically between the curl die 64 and the panel forming punch 66. A vacuum source connecting fixture 75 extends into vacuum passages 76 and 78 provided for applying a vacuum pressure to the upper surface of the panel forming punch 66.

The upper tool 61 comprises a curl forming punch positioner 84 having a projection 85 which defines the forming characteristics of the lower surface of the curl forming punch positioner 84. In addition, the panel forming die 86 is generally mounted for movement with the panel forming punch positioner 84. The panel forming die 86 is supported from the press ram via a plurality of springs 90 (not shown) selected to allow a "pause" period for the descending movement of the panel forming die 86 during the lowering of the press ram. .

Panel forming die 86, panel forming punch
The positioners 84 and their fixtures are provided with vacuum passages 92 and 93, respectively, so that a vacuum pressure can be applied to the lower surface of the panel forming die 86.

The details of the sequential work of the shell finishing in each secondary processing section are shown in FIGS. 9 to 11. The shell preform enters the open tool in the secondary section and is properly positioned on the lower tool. The large radius portion 52 and chuck wall 51 are supported by spring retainer pads 72 and the entire center panel 10 is supported somewhat above insert 71. The shell preform is positioned and held in place by the vacuum pressure acting on the upper surface of the panel forming punch 66.

In FIG. 9, the panel forming die 86 is connected to the chuck wall 51 by lowering the press ram, and the chuck wall 51 is fixed between the panel forming die 86 and the spring pressing pad 72. The spring pressure acting on the panel forming die 86 can be retracted more easily than the spring supporting the pressing pad, so that once the panel forming die 86 comes into contact with the chuck wall 51, the panel pressing die 72 is put in place by the spring pressing pad 72. It is held and begins to pause even if the press ram keeps descending. After that, panel molding punch positioner 8
4 contacts the lip body 53.

As is apparent from FIGS. 9 and 10, by continuing the downward movement of the press ram, the panel molding punch positioner 84 is moved to the shell lip 53 of the shell.
Begins to extrude into its desired final shape. The shell preform has a panel forming die 86 and a spring retainer pad 72.
It remains fixed in between and the panel forming die 86 remains paused until the bottom of the spacer 96 contacts the base plate, as shown in FIG. 8, by the downward movement of the press ram.

Once the bottom of the spacer 96 is in contact with the base plate, the press ram further lowers the tool, causing the panel forming die 86 to move downward, as shown in FIG. The pressing pad 72 is also moved downward. The insert 71 now has a raised portion 9 positioned relative to the shell preform panel 50.
1 is provided. The lowering movement of the spring retainer pad 72 causes the panel 50 to fully rise relative to the rest of the shell preform, reducing the distance between the upper end of the shell preform and the panel 50.

The shell material from the large radius of curvature portion 52 begins to open from the spring retainer pad 72 and the panel forming punch 66 and panel forming die (FIGS. 9 and 10).
Wrap around the edge of. This winding operation is performed under a precision control condition with almost no drawing of the shell material, and by correcting the large radius of curvature portion 52 to form the recess 98, it is possible to manufacture a pressure-resistant panel for finishing shell. it can. This resists the tendency of panel 50 to bend downward during shell molding, resulting in a flat finished panel. At the same time, the shell lip body 53 enters the curl die 64 and is subjected to finishing shaping processing.

The tool is shown in the closed position in FIG. The finish shell 48 has a recess 98 and a hook, ie an outer curl edge of relatively small radius of curvature,
It comprises a pressure resistant panel 50 surrounded by a die curl bending lip 53 suitable for seaming on a can. The reason why the "seagull wing" lip body 53 is formed in the primary working portion 10 will be easily understood. By precurling the outer portion of the lip body 53 to a relatively steep radius extending to the edge of the shell, the outermost portion of the lip body 53 resists die curl bending and tries to maintain a relatively straight state. You can overcome natural tendencies. In the primary processing portion, the curved portion of the lip body 53 is formed so as not to be steeper so that it extends not only outward from the chuck wall 12 but also upward. The lip body 53 can obtain some movement distance. Lip body 5 at the primary processing section
If 3 is formed so as to extend from the chuck wall 12 at a desired finishing angle, the outer edge of the die curl cannot be satisfactorily bent.

As a result of the above work, the wall thickness is uniform over the entire cross section, and the chuck wall 12 and the curl inner diameter, that is, the interval between the end edges of the curl bending lip body 53 is uniform. A shell can be manufactured.

Another embodiment of the upper tool is shown in FIG. 12, where the finishing shell is coined and reinforced around the outer edge of the panel adjacent wall 98. Although the shell coining is typically done in a separate coining press, the embodiment of FIG. 12 allows coining as part of the molding process, eliminating the need for separate equipment and steps. An annular groove for accommodating the coining ring 97 and the spacer 99 is provided in the center of the panel molding die 86. The coining ring 97 is fixed by the retainer 101 attached to the panel forming die 86. The spacer 99 is such that when the tool is completely opened as shown in FIG. 12, the working surface 100 of the coining ring 97 is the shell 48.
, And the compressive force sufficient to properly coin the outer edge of the panel 50 of the shell 48 is selected.

When the tool begins to open, the panel forming die 8
The vacuum pressure acting on the shell 48 via the vacuum passage 92 of 6 raises the shell 48 together with the upper tool 61.
The vacuum pressure is also applied to the shell 48 from the panel forming punch 66.
And the shell 48 is lifted from the lower tool 62,
It is necessary to apply a higher vacuum pressure to the upper side of the shell 48 than to the lower side. Further, the pressing pad 7 by the spring 74
The upward movement of 2 serves to facilitate the initial ejection of the shell 48 from the lower tool 62. Once the shell panel 50 is separated from the machined surface of the panel forming punch 66 and insert 71, a low pressure vacuum is released through an additional opening (not shown) in the machined surface.

As a result, in order to lift the finishing shell 48 from the lower tool 62, a small amount of vacuum needs to be applied to the upper tool 61.

After the upper tool 61 lifts the shell 48 sufficiently away from the lower tool 62, the raising operation of the retainer 80 and the panel forming die 86 continues, and the raising operation of the panel forming punch positioner 84 stops. Immediately after the above portion is separated from the shell 84, the shell 48 is separated from the tool for the secondary processing section and is carried out of the shell forming apparatus.

Although the above-mentioned embodiment is a preferred embodiment of the present invention, the present invention is not limited to this embodiment and does not depart from the scope of the present invention described in the claims. It should be understood that variations can be made.

[Brief description of drawings]

FIG. 1 is a plan view of a general beverage can with a part cut away to show a cross section of a joint portion between a can body and an end portion.

FIG. 2 is a cut-away reduced cross-sectional view of a can end shell provided by the present invention.

FIG. 3 is a partial view of a thin metallic material showing the shape of a blank to be cut according to the present invention.

FIG. 4 is a partial enlarged view (about 2.5 times) of a tool for forming a partially finished shell for use in the primary working portion according to the present invention.

FIG. 5 is a partial enlarged view (about 2.5 times) of a tool for forming a partially finished shell for use in the primary working portion according to the present invention.

FIG. 6 is a partially enlarged view (about 2.5 times) of a tool for forming a partially finished shell for use in a primary working portion according to the present invention.

FIG. 7 is a view showing a peripheral shape of a tool for forming a partially finished shell, which is used in the primary working portion according to the present invention.

FIG. 8 is a similar enlarged view of a part of the tool for finishing the forming of the shell in the secondary processing part according to the present invention and a view showing the sequential work thereof.

FIG. 9 is a similar enlarged view of a part of the tool for finishing the forming of the shell in the secondary working portion according to the present invention and a view showing the sequential work thereof.

FIG. 10 is a similar enlarged view of a part of a tool for finishing the forming of a shell in a secondary processing part according to the present invention and a view showing a sequential operation thereof.

FIG. 11 is a similar enlarged view of a part of the tool for finishing the forming of the shell in the secondary working part according to the present invention and a view showing the sequential work thereof.

FIG. 12 is a view showing a modified example of the secondary processing portion, FIGS.
It is a figure similar to 1.

[Explanation of symbols]

 S ... Thin metal material CH ... Cover hook 10 ... Flat center panel 11 ... Recessed part 12 ... Chuck wall 13 ... Curl edge 14 ... Die cutting edge 16 ... Material line height 18 ... Die forming ring 24 ... Aperture ring 25 ... Center pressing pad 30 ... Blank punch 32 ... Knockout positioner 34 ... Punch center 48 ... Shell 49 ... Curved portion 51 ... Chuck wall 52 ... Large radius portion 53 ... Lip body 61 ... Upper tool 62 ... Lower tool 64 ... Curl die 66 ... Panel forming punch 71 ... Insert 72 ... Spring pressing pad 74 ... Spring 76, 78 ... Vacuum path 84 ... Molding punch / positioner 86 ... Panel forming die 90 ... Spring 92, 93 ... Vacuum path 97 ... Coining ring

Front Page Continuation (72) Inventor Omar El Brown 45429, Ohio, United States Naplesine Drive, Dayton 148 (72) Inventor Amal Sea Flaze 45429, Ohio, United States, West Strop Road 355 (72) Inventor James Earl Greg 45066, Ohio, USA, Factory Road 410, Boxing 477, Springboro, (477) Inventor David Kay Wayne 45459, Ohio, USA, Lightbeam Drive 311

Claims (2)

[Claims] 1. A shell for a can used for manufacturing a can end portion, the shell being formed of a thin metal plate, the direction being perpendicular to the crystal of the metal of the thin metal plate rather than the direction along the crystal. A wide, non-circular, rounded blank formed by pressing, in a can shell, a generally flat central panel formed in the central portion of the blank, and the central panel A chuck wall formed to surround the periphery of the blank and extending upward; and a chuck wall extending upward from an inner lower edge of the chuck wall toward a peripheral edge of the central panel, and A panel wall that defines a recess that surrounds the central panel at a joint portion between the central panel and the chuck wall, and extends outward from an upper end of the chuck wall while being generally parallel to the central panel. Do And having a lip member, a shell for a can. 2. A curl edge portion is formed on the lip body,
The radius of curvature of the outer portion of the curl edge portion is smaller than the radius of curvature of the inner portion of the curl edge portion,
The can shell according to claim 1.