An Improved Method of Ascertaining or Testing the Airtightness of Filled and Closed Preserve-Tins or Boxes.
Year: 1897

page_text: Date of Application, 18th Feb., 1897
Complete Specification Left, 25th Oct., 1897-Accepted, 24th Dec., 1897
An Improved Method of Ascertaining or Testing the Airtightness of
Filled and Closed Preserve-Tins or Boxes.
I, OTTO ASCHE, of 7 rue Cail, Paris, France, Engineer, do hereby declare the
nature of this Invention to be as follows:
My Invention relates to an improved method of ascertaining or testing the air-
tightness of filled and closed preserve tins or boxes before placing them in the
autoclave, whereby the slightest defect in the soldering, in the fitting, or in the
metal, can be promptly ascertained.
When preserve tins or boxes are placed in the outoclave the internal pressure
resulting from the expansion of the contents and from the formation of vapour
therein, causes the somewhat concave bottoms of the boxes to bulge out and
present a convex form. Those tins or boxes which do not show a convex form
and remain unchanged in appearance on leaving the autoclave have to be thrown
aside.
Now, for the purposes of my invention, I utilize the elasticity or flexibility of
the metal forming the bottoms of tins or boxes in such a way as to detect the
existence of any defect in the closure or in the metal previous to placing them in
the autoclave. The results, which enable me to judge as to the soundness of each
tin or box, are the reverse of those observed after treatment of the boxes in the
autoclave, that is to say, if the box is found unaltered it is airtight and sound,
while boxes which show a convex bottom after testing, are defective, and are set
aside to be resoldered before being placed in the autoclave.
The testing is carried out in an apparatus comprising an air rarefying or
vacuum vessel of suitable form in connection with a vacuum pump. One or more
plates provided with a washer of rubber, or other suitable material and having a
central cavity, are arranged to support or hold the tins or boxes to be tested, and
these plates are perforated at their centre and are in communication with the air
vessel.
In some cases I may use two such supports one for the top and one for the
bottom of the tin or box.
The apparatus may be operated by hand or by mechanical means, and is fitted
with the necessary cocks and tube connections for obtaining a vacuum.
The tins or boxes are each placed on one of the plates or supports provided with
the hollow washers, and a vacuum is formed in the cavity underneath the bottom,
or bottoms, of such boxes, thereby causing said bottoms to bulge out and assume
a convex form.
If any of the boxes are defective, in the soldering or otherwise, air is drawn
into the enlarged internal space and prevents the box, on being removed from
the testing apparatus, resuming its original form.
No noticeable alteration can be found in any of the sound boxes after removal
from the testing apparatus, as the atmospheric pressure immediately causes them
to assume their initial form.

page_text: may, in some cases, substitute for the vacuum apparatus the attractive action
of magnets, or of electro-magnets.
I thus provide the means for ascertaining or testing the air-tightness of filled
and closed preserve tins or boxes, and enable them to be sorted before being
introduced into the autoclave, while, at the same time, I obviate the losses
occasioned through defective boxes.
1007
ERNEST DE PASS,
Chartered Patent Agent,
78, Fleet Street, London, &
5A Market Street Nottingham.
Agent for the Applicant.
An Improved Method of Ascertaining or Testing the Airtightness of
Filled and Closed Preserve-Tins or Boxes.
I, OTTO ASCHE, formerly of 7 rue Cail, and now of 17 rue Philippe de Girard,
Paris, France, Engineer do hereby declare the nature of this Invention and in
what manner the same is to be performed, to be particularly described and ascer-
tained in and by the following statement, reference being had to the accompanying
drawings and to the letters and figures marked thereon, that is to say:
My invention relates to an improved method of ascertaining or testing the air-
tightness of filled and closed preserve tins or boxes, whereby the slightest
defects in the soldering, in the fitting, or in the metal of such tins or boxes can
be, instantly detected, thus obviating the losses resulting from placing badly
closed boxes into the autoclave.
In order that my invention may be fully understood, I will proceed to explain
the same in detail.
The top and bottom of the tins or boxes are formed from metal plates generally
stamped in concave form and which, under the influence of variations of pressure,
become more or less distorted and so form true flexible membranes.
In this manner, when the boxes, after being heated, are removed from the
autoclave, it will be noticed that the tops and bottoms of air-tight boxes (called
good boxes) have changed from the concave to a convex form, whereas with non
air-tight boxes (called bad boxes) they have undergone no change at all.
The convexity of the plates in the first case is due to the expansion of the con-
tents of the box, and especially to the pressure from the vapours formed inside the
box, while in the case of bad boxes the internal gases escape by leakage which
permits the outer air to enter the box, so that no internal pressure is exerted on
the tops and bottoms, and consequently no convexity or bulging is produced.
On removal from the autoclave, it is too late to remedy any defect in the air-
tightness of bad boxes.
Now, my invention has for its object to so utilize the flexibility of the tops
and bottoms as to detect the existence of any defect in the closure of the boxes
before placing them into the autoclave. To this end I proceed as follows:
-
I place the filled and closed box so that either its top or bottom rests on a sup
porting plate or tray provided with a washer of rubber, or other supple material,
the centre of which is in connection with a vacuum pump. The suction produced
on the bottom of the box causes it to alter in shape and become convex the same
as would an air-tight box when heated in the autoclave. A partial vacuum is

page_text: thereby produced in the interior of the box under the influence of which the
slightest fissure in such box allows air to enter. Consequently, if air has entered
the box, the bottom, distorted by the vacuum, is unable to resume its original
form on being removed from the support or tray in connection with the vacuum
pump.
Instead of operating only on the bottom of the box, as before described, the
operation may be performed simultaneously on both the top and bottom of the
box, thereby causing both to become convex. This is effected by placing the box
between rubber washers on the supports or trays in connection with the vacuum
pump.
Defective boxes, when pressed by the finger, at top or at bottom, emit a cracking
noise; such a box is technically termed in France boite-" floche," and these boxes
when found can be easily repaired before being placed in the autoclave, but sound
boxes return immediately to their original form under the pressure of the
atmosphere, and the test of their soundness can be ascertained by pressing on
them with the finger.
The accompanying drawings show, by way of example only, apparatus for
carrying out the method by operating either on the top or on both the top and
bottom simultaneously.
Figs 1 and 2 show a revolving apparatus to which I make no claim.
Fig 3 is a modified apparatus which is used for bringing both the top and
bottom of the boxes under the action of the vacuum pump.
A reservoir or vessel A (in which a vacuum is maintained by the pump B)
carries on its cover the means for working the pump B, either by hand or by
power. The driving shaft is provided with a worm driving a wheel fixed on a
hollow shaft b. This latter carries, at its end, a wheel D, the hub E and spokes c, e
of which are also hollow. At the outer ends of these spokes are rubber covered
plates on which are placed the boxes to be tested: Below each of these plates
is, a two-way cock G for establishing communication between the box to be tested
and the vacuum vessel A. The vacuum acts on the bottom of the boxes and holds
it tight against the washer thus preventing the outer air from entering beneath
the box, and on the vacuum continuing to act, the bottoms thus acted upon become
bulged out. A depression of suitable form in the washer F permits the bottom to
follow the action of the suction according as this latter is more or less strong.
The top of the box, being of concave form is unable to yield in the direction of
the suction, the result is that the distortion of the bottom through suction brings
about in the interior of the box a partial vacuum which, if the box be not air
tight, allows air to enter.
The wheel D is caused to revolve at a suitable speed to allow the attendant the
necessary time for placing the boxes to be tested on to all the supporting plates
or trays and to allow them to remain exposed to the action of the vacuum the
requisite time.
In order to remove the tested boxes from the apparatus it is only necessary to
turn the cock G so as to admit air under them, after which the effect produced
can be ascertained by removing the boxes.
Fig 3 shows another arrangement having for object to cause the vacuum to act
simultaneously on both the top and bottom of the box. The parts for producing
the suction are the same as in the previous arrangement, but instead of one
support or tray there are two for each box; the upper one H being a fixture and
communicating through tubes, with the reservoir A. The cock G is placed at the
most convenient part within reach of the attendant. The support, or tray K
slides in a spring box N; a pedal J is employed to produce a sufficient opening
etween the supports or trays H and K for the introduction of the box to be
ested. The communication between the movable support or tray and the reservoir
s established by a flexible tube M and cock G', the handle of which latter, may, if
equired, be connected to the handle of the upper cock.
I may, in some cases, substitute for the vacuum apparatus, the attractive action

page_text: of magnets, or of electro magnets, for effecting the bulging out of the bottoms
of the boxes to be tested.
Having now particularly described and ascertained the nature of my said
invention and in what manner the same may be performed I declare that what I
claim is:
1. The improved method of ascertaining or testing the air tightness of filled
and closed preserve tins or boxes, in which the flexibility of the bottom of such
tins or boxes is utilized for momentarily distorting said bottom under the action
of a vacuum, or under magnetic action, substantially as described.
2. The improved method of ascertaining or testing the air tightness of filled
and closed preserve tins or boxes, in which the flexibility of the top and bottom
of such boxes is utilized for distorting both the said tops and bottoms under the
action of a vacuum, or under magnetic influence, substantially as described.
3. The improved method of ascertaining or testing the air tightness of filled and
closed preserve tins or boxes whereby the sorting with certainty of the tins or
boxes, after their passing over the plate of the vacuum apparatus, or over magnets,
is effected, the tightly closed tins or boxes alone regaining their original form,
substantially as described.
1007