Improvements in Air-tight Sheet Metal Cans and other Vessels.
Year: 1891

page_text: Date of Application, 8th Apr., 1891-Accepted, 9th May, 1891
COMPLETE SPECIFICATION.
Improvements in Air-tight Sheet Metal Cans and other Vessels.
I, HERBERT JOHN ALLISON, of 52 Chancery Lane, London, in the County of
Middlesex, Patent Agent, do hereby declare the nature of this invention (which
has been communicated to me from abroad by The Franco-American Patent Can
Opening Company, a Corporation of 78 Hudson Street, in the City of New York,
in the State of New York, and United States of America), and in what manner the
same is to be performed, to be particularly described and ascertained in and by
the following statement :-
These inventions relate to that class of sheet metal cans and other vessels or
receptacles which after being filled are hermetically closed by soldering, and are
opened by tearing away a portion of the material of which the can or vessel is
composed along the line of an incision made partially through the metal.
In cans and boxes of this character experience has shown it to be necessary in
order to render the tearing operation satisfactory in practice, that means should be
employed to stiffen or strengthen the thin metal on one side of the line of the
incision sufficiently to enable it to properly resist the force of the tearing action
on the other side of the line, thereby avoiding the buckling or bending of the metal
which would make the tearing difficult.
These improvements are specially applicable to the ends, that is, the heads or
covers, of metal cans and vessels of the character described.
In the drawings, Figure 1 is a plan view of the head or cover of a cylindrical
can or box constructed in accordance with the first part of these improvements,
before its edge has been turned over to form the usual flange;
Figure 2 is a vertical cross section of the same head or cover, taken on the lineæ æ
in Figure 1;
Figure 3 is a cross section of another head or cover showing a modification of
construction;
Figure 4 is a plan of a head or cover for a similar can, which is constructed
according to the second part of these improvements and is represented in the
condition in which it is before its flange has been formed;
Figure 5 is a front view of a finished can provided with a head such as is shown
in Figure 4;
Figure 6 is a plan of another head for a can, illustrating another mode in which
the second part of these improvements may be applied; and
Figure 7 is a front view of a finished can fitted with a head or cover made from.
the blank shown in Figure 6.
The first part of these improvements consists in making an incision partially
through the metal of the head or cover, inside of the outer margin or edge thereof,
concentric with and at any convenient distance from the margin, and continuing
this incision around nearly the entire circumference of the head or cover, but
deflecting it outward to the margin on each side of a narrow space at a single
point in its path where it meets a part of the metal which is formed into a short
laterally projecting flap or tongue, and in combining with such incision a corruga-
tion or rib made in the metal between the incision and the margin coincident or
nearly so with the circular portion of the path of the incision, and of the requisite
depth to give the material sufficient rigidity to resist the effect of tearing
away the section of material inside of the incision when the can or box is
opened.
B. Fig. 1, represents one end or head of the can or box. It may be taken as
either the top or cover, or as the bottom, both being substantially alike in construc-
tion. It is made in the usual way of a flat disk of sheet metal having a short

page_text: circumferential downwardly extending flange a. Inside of its outer edge or margin
an incision c c is made partially through the metal in the circular path shown in
the figure. This incision is continued around nearly the entire circumference of
the cover or bottom, as shown, until at bb it meets a narrow portion of the metal
which is extended outward beyond the margin into a slightly projecting flap or
tongue g. At these points bb, the incision is deflected outwardly clear up to the
exterior edge of the cover or bottom, and its path is made to conform to the outline
of the flap or tongue, as shown. At any suitable point between the incision and
the exterior edge, the corrugation or rib d d is formed, which, as will be seen, is
coincident in direction with, and of somewhat greater extent than the incision, and
may or may not terminate at each side of the tongue g. The depth of this corru-
gation may preferably be from one sixteenth to about three thirty-seconds of an
inch, and in the case of very large cans or boxes somewhat more. The incision
may be of a depth equal to say one-half of the thickness of the metal or a little
more or less.
If desired, instead of placing the corrugation between the incision and the margin
of the cover or bottom, it may be made close up to the incision, or the latter may
be put in its angle or corner, as represented at c in Fig. 3. The corrugation
may be formed in either the outer or inner surface of the cover or bottom, and
the incision may in like manner be made in such outer or inner surface.
The mode of opening the can or other vessel will be apparent. The tongue g
may be grasped by the fingers or by a suitable instrument or its end may be
inserted in a properly constructed key, and it may then be bent or rolled inward
and the entire cover or bottom, excepting only the narrow section outside of the
incision, will thereby be torn away and the can fully opened.
The second part of these improvements is designed to be applied to cans and
boxes the heads or covers of which are made by striking or stamping them in dies
and presses to form the circumferential flange which overlaps and incloses the ends
of the vertical wall or body of the can. It consists in a can head or cover, or can
end or bottom, formed with a circumferential flange and having on one side of
its flat surface an incision made partially through the metal at the top or upper
side of the flange just at the point where the metal is turned over laterally to
form the flange, thereby enabling the can to be opened either by stripping off the
flange itself along the line of the incision on one side and along the line of the solder
on the other side, as represented in Fig. 5, or by tearing out the entire top or
bottom inside of the incision line, as shown in Fig. 7.
In this manner all the needed resistance against the stripping or tearing operation
is provided by the stiffness and strength of the flanged portion of the cover or
bottom, and a can is furnished which is easy and cheap of construction and efficient
in operation.
D, Fig. 4, represents the central portion and a the flange portion of one head of
a can or box constructed in accordance with this second part of these improvements,
and it exhibits the flange portion a before it has been turned over to form the
flange. Where it is so turned over, its top, and consequently the outer edge of
the cover or bottom, will be coincident with the double line in the figure marked bb,
and it is at this point and along this line that the incision is made. The incision
will be clearly seen at ce in Fig. 5, and it will be manifest that by thus locating it
where the metal is the most rigid all the stiffness of the side of the flange and of
the corner or fillet where the flange is turned over, is obtained to oppose as a
resistance or fulcrum against the operation of stripping off or tearing away a part
of the material to open the can.
Moreover, by this method of construction another very important result is
secured. This is the opening or spreading out of the incision throughout its
entire extent by the operation of turning the metal over to form the flange. This
materially augments the weakening of the metal along the line of the incision, and
thereby greatly facilitates the opening of the can, and will be found to operate very
satisfactorily in practical use.

page_text: This improvement may be so applied as to operate either upon the flange only
of the can or box, or upon the flat or central portion D of the cover or bottom.
Figures 4 and 5 represent the first of these modes of carrying out the invention,
and Figures 6 and 7 the second. In each of these figures 9 denotes a short lateral
outward projection of the metal which forms the customary tongue by means of
which the stripping or tearing is started. The flange a of Figs. 4 and 5 is soldered
in the usual way to the body of the can or box on the line n n, and by grasping
the tongue with the fingers, or inserting the end of it in the slot or opening of a
suitably shaped key, the entire flange may be stripped off along the line of the
incision c c on one side of it and along the solder line non its other side, thus
readily opening the can.
In this instance, the tongue g is formed by slightly prolonging the flange a.
In Figs. 6 and 7 however, the tongue is formed by an outward extension of the
flat surface of the cover or bottom, and when this projecting part is gripped by
the fingers or by a suitable tool or placed in the slot of the key as in the other
example, and the metal is pulled forcibly upward, the entire central portion D of
the cover or bottom inside of the line of the incision c¹ c¹ may be torn out, thereby
completely exposing the contents of the can.
The incision should preferably be made in the metal before the flange of the
can or box is turned over. This course will not only be found to be usually the
most convenient in practice, but it secures the advantage of having the incision
opened out by the operation of turning the flange over, as above set forth. If
desired, however, the flange may be formed first and the incision produced in it
afterwards. Or the flange may be turned over, or struck up, and the incision made
in it at one and the same operation by the use of suitable dies, cutters and presses.
The incision may be made either on the upper or the under surface or face of the
cover or bottom, and it should preferably be of a depth equal to about half the
thickness of the sheet metal, but it may be slightly more or less.
All of these improvements are equally applicable to cans or vessels of square or
polygonal form.
Having now particularly described and ascertained the nature of my said inven-
tion, and in what manner the same is to be performed, I declare that what I
claim is :-
:-
First. A sheet metal can, box or other vessel having in one of its ends or heads
a circumferential incision made partially through the metal, in combination with a
circumferential rib or corrugation co-incident with, or adjacent to and independent
of, the incision, substantially as set forth.
Second. A sheet metal can, box or other vessel having a flanged end or head
containing a circumferential incision made partially through the metal thereof at
the point where the flange is turned down, substantially as described.
Dated this 7th day of April 1891
ALLISON BROS.,
Agents for the Applicant.