Improvements in and relating to Sheet Metal Cans and Similar Vessels, and to Devices for Opening the same.
Year: 1897

page_text: Date of Application, 16th Feb., 1897-Accepted, 12th Feb., 1898
COMPLETE SPECIFICATION.
Improvements in and relating to Sheet Metal Cans and Similar
Vessels, and to Devices for Opening the same.
We, JOSEPH WOOD HILL, Teacher, and RICHARD POTTER MCKAY, Mechanic,
both of Portland, in the County of Multnomah, State of Oregon, United States of
America, do hereby declare the nature of this invention, and in what manner
the same is to be performed, to be particularly described and ascertained in and
by the following statement:-
This invention relates to sheet metal cans and similar vessels and to devices
for opening the same by means of a ripping strip and key, the vessels being of
that class in which a strip of sheet metal is located within the sheet metal forming
the body of the vessel and imbedded in a fold of the same, one end of this strip
protruding outside of the vessel so that it may be seized and drawn outwards by
means of a key to sever the metal exterior to the vessel and give access to its
contents.
This invention is in the nature of an improvement upon the construction of any
or all key-opening cans in which the sheet metal is weakened in any way along
the line or lines of separation and in which a tongue of the metal between these
weakened lines projects and by the engaging of which with a key the can inay
be opened; or that class of cans in which a wire is imbedded in the can, or
soldered to the can along the interior in a fold or groove of weakened metal, the
can being opened by drawing the said wire through this weakened metal. In our
invention the metal is not weakened in any way as it is unnecessary to do so for
the purpose, the result being better and more economically accomplished by means
of a strip of tin-plate or sheet metal folded into the body of the can in the
manner hereinafter described. The tin or other coating of the sheet metal is in
no wise destroyed by using this strip of tin plate, as in the case where the metal
is broken or weakened, and by not using any wire to come in contact with the
contents of the can said contents are not discolored or injured. In our improved
mode of manufacture, there is no solder employed in any manner upon the inside
of the can.
This is an important feature, since it is well known that solder is
harmful to many kinds of canned goods because the combination of acids in the
goods comes in contact with the lead used in soldering, thereby forming the
injurious salts of lead.
This invention does away completely with all the various methods heretofore
employed of weakening the sheet metal by breaking, cutting, or thinning, either
by rollers, by dies, by a simple die co-operating with an anvil, or by any other
suitable device or devices.
In the drawing,
Figure 1, is a plan of the blank for the can body.
Figure 2, shows the blank folded, with the ripping or cutting strip enclosed
in said fold.
Figure 3, is an elevation of the completed can, showing the effect of the operation
of the key in opening it.

page_text: Figure 4, is a detail, showing the fold and one of the end seams in section.
Figure 5, is a similar view showing the can opened.
The body blank A, Figure 1, is a rectangular sheet preferably of ordinary tin-
plate, having in one end near the top, a T-shaped notch a, the width of the
stem of the T being equal to the width of the strip to be taken from the fold,
while its length is the same as that of the lap which is to form the side scam.
The
By means of suitable known apparatus, the blank A is folded lengthwise along
the lines a¹ a² into the shape shown in Figure 2, a strip of tin-plate or other
sheet metal B being at the same time enclosed in and filling the flat fold.
inner edges of the fold preferably meet along the line a, as seen in Figure 4,
but in any event the edges of the strip B are protected from contact with the
contents of the can.
The folded sheet and strip are then formed into a can body, the edge a³ being
lapped over the edge at to the line a corresponding with the end of the notch a,
and soldered on the outside. The heads Care then put on, each having an
annular counter sink c to form a flange c¹ fitting inside the can body, and an
outer flange fitting down over the outside of said body, the edge of the
flange being preferably doubled at c³ to enclose the raw edge. The flange is
soldered to the body on the outside.
We do not limit ourselves, however, to this construction of head and joint,
since any suitable mode of forming the heads and uniting them to the body
may be employed. We prefer however to use a seam which will project beyond
the body of the can to or nearly to the line of the flat fold as indicated
by the upright dotted line in Figure 3, so that when the cans are packed, they
will be in contact or nearly so at top and bottom as well as at the level of the fold.
It will thus be seen that our flat fold is superior to any other shape, in that it
economizes space and obviates any tendency of the fold on one can to ride up
over the fold on an adjacent can.
The end of the ripping or cutting strip B is left projecting at the side seam,
lying flat against the side of the can. It is thus readily engaged by a key D
preferably composed of a piece of stout wire, bent at one end to form a handled,
and flattened at the other end to permit the cutting of a slot d which is slipped
upon the end of the strip B. When the key is turned to roll up the strip, the
metal composing the fold is torn apart along the lines a¹, the portion between said
lines being wound up on the key with the strip B. This leaves the upper part
of the can free, as shown in Figure 5, so that it can be lifted off.
The steps in our method of forming the can above described may be summed up
as follows:
The coated blank of sheet metal is suitably notched to provide for the pro-
jecting of the strip of tin-plate through the body blank, or it may be folded into
the body blank without notching.
on a
After the blank is folded it may be treated exactly as a plain body blank is
used in the formation of a can under ordinary circumstances. The strip of tin
plate folded into the body blank forms no obstacle to soldering the seam
horn in the usual manner, as it is no objection if the solder does cover the strip
of tin plate, (although this is unnecessary to keep it in place), because the action
of the key is such that it will tear loose and rip open the can even if the strip
is soldered to the body of the can unintentionally. The heads may be put on and
the can completed in the usual manner. The action of our combination key and
strip of tin plate contained in the fold of the body of the can is positive, thus
obviating the difficulty experienced in many key-opening cans, which have been
found to be impracticable because of increased cost of manufacture or because of
the difficulty arising when the weakened lines or thin portions of the can body
are not exactly parallel and of the same thickness, the portion of the body con-
tained between these lines tearing unevenly, obliquely or transversely to the
line of separation and breaking off, thus defeating the object in view.
In Figures 4 and 5, we have shown the folded edges of the can as coming close

page_text: together. As a matter of fact it would make no difference if they did not meet
by a sixteenth of an inch, since the contents of the can would not in any case
come in contact with anything but the inner surface of the tin-plate cutting strip
and would receive no damage thereby. In cases where the can contains liquids
it would be of advantage to have the edges a slightly separated, so that when the
can is opened about as much as is shown in Figure 3, it can be turned over to
let part of the contents run out.
One other point of advantage worth noting is this: in all other devices for
opening cans by means of tearing out the body with the aid of a key acting in
conjunction with a part of the body of the can running along or between weakened
parallel lines, and in that class of cans in which a wire is used to cut the can, a
more or less rough or serrated edge is left on the upper part of the can where it
is torn open.
This is all avoided in our mode of construction and operation, as shown in
Figure 5, the surface being smooth and rounded and re-inforced since it is formed
by turning over the can body, the edge that is cut at a¹ being below the top of
the separated can at a³. This mode of construction would not interfere with taking
out the contents of the can in case it was solid, and the person using the can
would not be in any danger of cutting the fingers on the sharp torn edges of
the same.
Having now particularly described and ascertained the nature of our said
invention, and in what manner the same is to be performed, we declare that what
we claim is: -
1. A can or other vessel constructed of sheet metal having a flat strip of sheet
metal folded in the body thereof, the strip being made a little longer than the
width of the can body blank, so as to project at the end, the metal of the body
of the can having been in no way weakened or prepared for the reception of this
strip, except the folding, substantially as described.
2. A can body having a strip of sheet metal contained within an outwardly
projecting flat fold, which extends around the can body, said strip lying parallel
with said body, one end of said strip terminating with the outside edge of the
lapped side seam and the other end of said strip projecting a convenient distance
from the other edge of the lapped seam whereby said strip may be engaged by a
proper key so that when the key is turned, the contained strip and the outer
portion of the fold are wound up together, and the body severed along the upper
and lower edges of the fold, substantially as described.
3. A sheet metal can having a portion of its body folded into an outwardly
projecting fold or bead, composed of the flat portions between the lines a² a
lying against the body of the can, and the flat portions between the lines a¹ a¹
lying parallel with the body of the can, the folds at a¹ being at the upper and
lower edges of said flat fold, and a flat cutting strip of metal enclosed in and
filling said fold and lying parallel with said can body, whereby the fold
and enclosed strip project but slightly beyond the wall of the can and
offer a broad, flat outer surface to come in contact with adjacent cans when
packed, substantially as described.
4. A blank for a can body consisting of the rectangular metal sheet A having
in one end near the top, the T-shaped notch a, substantially as described.
W. E. HEYS & SON,
Agents for the Applicants.