Sheet metal container making – Method – Forming or treating metallic closure
Reexamination Certificate
1999-08-31
2003-03-18
Sipos, John (Department: 3721)
Sheet metal container making
Method
Forming or treating metallic closure
C413S014000, C413S016000, C413S019000
Reexamination Certificate
active
06533518
ABSTRACT:
BACKGROUND OF THE INVENTION
A. Field of the Invention
This invention relates to the art of manufacturing ends for cans, such as, for example, ends that close off aluminum beverage cans, ends for cans containing human or animal foods, and ends for containers for consumer products such as tennis balls. The invention also relates to a press that is used to make can ends and the methods by which such a press operates to form an end out of a sheet or coil of stock material.
B. Description of Related Art
It is well known to draw and iron a sheet metal blank to make a thin-walled can body for packaging beverages, such as beer, fruit juice or carbonated beverages. In a typical manufacturing method for making a drawn and ironed can body, a circular disk or blank is cut from a sheet of light gauge metal (such as aluminum). The blank is then drawn into a shallow cup using conventional cup forming punch and die equipment. The cup is then transferred to a body maker or can forming station. The body maker draws and irons the side walls of the cup to approximately the desired height and forms dome or other features on the bottom of the can. After formation of the can by the body maker, the top edge of the can is trimmed. The can is transferred to a necking station, where neck arid flange features are formed on the upper region of the can. The flange is used as an attachment feature for permitting the lid for the can, known as an “end” in the art, to be secured to the can.
The end is the subject of a different manufacturing process and involves specially developed machines and systems to manufacture such ends in mass quantities. Representative patents describing end manufacturing methods and presses used to make such ends include Buhrke, U.S. Pat. No. 4,106,422, and Herrmann, U.S. Pat. No. 3,888,199. After the ends are manufactured they are bagged in large stacks (known in the art as “sticks” or “in stick form”) and sent to a site where the cans are filled with a food,.beverage, or other product.
In the Buhrke '442 patent, a sheet or web of end material is fed into a press. The sheet is pierced, notched, and lanced according to a predetermined pattern at longitudinally spaced intervals to define a series of identical individual can top blanks. The blanks are separated in the web from each other by substantial openings void regions, but linked together by flexible “links”, that is, portions of the web material that connect the blanks together. See, e.g.,
FIGS. 1
,
2
and
3
of the Buhrke '422 patent. After the sheet has been so formed, the sheet is sent to a series of stations of a single progressive die that complete for formation of the end in the web or sheet of material. The web material and links act as a carrier of the blanks until the ends are cut out of the web, whereupon the ends are sent to edge curling and finishing stations within the press.
While the Buhrke system was put into practice and used for a period of years during the early 1980's, it was prone to problems and ultimately unsuccessful. In particular, the void features formed in the sheet of material in the beginning of the operations in the press created an elastic condition when the sheet was indexed through the press, leading to registration problems between the sheet of material and downstream work stations that formed the closure and other features in the end. More specifically, the void features led to relative movement between various portions of the sheet when the indexing mechanism moved the sheet through the press, resulting in a mis-alignment between the tools of the work stations and the portion of the sheet containing an end in various states of completion. Furthermore, the machine had a relatively low metal realization since the design requires material to carry the ends through the press. The resulting down-time to change the position of the dies, slow speed of operation, poor quality of ends due to the misalignment, and overall maintenance and metal utilization problems experienced by machines made in accordance with the '422 Buhrke patent eventually resulted in the abandonment and eventual replacement of such machines. The company is no longer in the business of making shell forming presses.
The Herrmann '199 patent also describes an end manufacturing process performed on a sheet of end material. In particular, a sheet of material is fed into the press, and initial forming operations and lancing of a press tab opening feature are performed. Then, the end is blanked. The blanked ends are then fed to downstream work stations, where various additional forming operations are performed on the ends. The Herrmann '199 patent was commercialized for a short time, but such machines were.soon abandoned and replaced.
During the mid-to-late 1980s, the art moved away from systems that attempted to form a complete end in a single machine, as typified by the Herrmann and Buhrke patents. The art adopted a two-stage type of system using a shell press that formed shells from a coil of stock material, and one or more end conversion presses that converted the shell into a finished end. A representative prior art shell press and end conversion system is illustrated schematically in FIG.
1
. The system of
FIG. 1
, described below, was a much more complex and capital-intensive system than those systems used previously. However, the increased capital investment required to build an end making line such as shown in
FIG. 1
was believed justified since the system proved to be more reliable, required less maintenance and down time, and was capable of operating at higher speeds to produce more can ends per minute than prior systems.
The end manufacturing system
10
of
FIG. 1
operates as follows. A coil stock feed mechanism
12
supplies a continuous sheet of end material (e.g., aluminum or steel), to a shell press
14
. The shell press has a set of tools that form a shell in the sheet of end material and blank the shell from the sheet. Shell presses such as shown in
FIG. 1
are made by companies such as Formatec Tooling Systems, Inc. and Redicon Corp. and are well known in the art. The shell press
14
in the instant example is a twenty four-out press (i.e., it forms twenty four shells in the sheet of material a direction transverse or oblique to the direction of movement of the sheet in the press). Shells are ejected out both sides of the press
14
and sent to curlers
16
, where an edge curl is formed in the periphery of the shell, resulting in the shell
15
shown in FIG.
1
A.
After curling, the shells are placed in stick form and moved along track work indicated at
20
to a balancer
22
. The balancer
22
is a robotic distribution machine. It is needed because the curlers
16
are supplying shells along six sets of track work
20
, whereas in the downstream direction there are only four sets of track work leading to four liner machines
24
. The balancer
22
is used to collect the ends and appropriately distribute them to track work leading to the lining machines
24
. The lining machines
24
add a compound liner to the shells. The lining machines supply the shells to a drying machine
26
(if a water-based compound is used), which dries the compound liner with forced air. The drying machine
26
is not needed if a solvent-based compound is used.
The drying machines
26
supply the shells along another set of track work
30
to a second balancer
32
. The balancer
32
supplies shells in stick form to three sets of track work,
34
,
36
and
38
leading to three separate shell conversion presses
40
. The conversion presses
40
take the shells of FIG.
1
A and complete the formation of the end features in the shell. The conversion presses
40
also have a set of tools that receive a continuous sheet of tab stock from a source
42
and form tabs in the tab stock. The conversion presses
40
attach the tab to the shell, complete the formation of the ends, and supply the finished ends to three sets of track work
43
leading to three bagging stations
44
. The converted ends are bagged
Forrest Randall G.
Turner Timothy L.
Young Carlton
Huynh Louis
McDonnell & Boehnen Hulbert & Berghoff
Rexam Beverage Can Company
Sipos John
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