US3754369A

US3754369A - Sealing and charging containers with gas

Info

Publication number: US3754369A
Application number: US00247842A
Authority: US
Inventors: T Copstead
Original assignee: Electronic Data Controls Corp
Current assignee: Electronic Data Controls Corp
Priority date: 1972-04-26
Filing date: 1972-04-26
Publication date: 1973-08-28
Anticipated expiration: 1990-08-28

Abstract

Sealing and filling a metal container having a seamed body construction and an aerosol discharge valve disposed at an opening in the top of the container. The container is advanced in stepped increments along an assembly line including a plurality of stations. At the first station, the discharge valve is crimped to the container body to close the opening therein. At a second station, the discharge valve is temporarily opened and a liquid sealant such as glycerol is sprayed into the container through the discharge valve to coat the interior surfaces of the container. At a third station, the discharge valve is again temporarily opened and the container is charged with a supply of pressurized helium.

Description

White States Patent 1 1 Copstead 1 Aug. 28, 1973 54 I 1 3 2.3 3; ND CHARGING CONTAINERS R'im r li qm crfrayis,SNskhse Attorney-Channing L. Richards, Dalbert U. Shefte [75] Inventor: Terrance R. Copstead, Charlotte, et a1.

N.C. [73] Assignee: Electronic Data Controls [57] ABSTRACT Corporation, Winston-Salem, N .C.

2 Claims, 4 Drawing Figures Patented Aug. 28, 1973 3,754,369

2 Sheets-Sheet l Patented Aug. 28, 1973 3,754,369

2 Sheets-Sheet 2 SEALING AND CHARGING CONTAINERS WITI-I GAS BACKGROUND OF THE INVENTION It has been proposed heretofore in copending U.S. application Ser. No. 796,095, filed Feb. 3, 1969, and in U.S. application Ser. No. 14,350, filed Feb. 26, 1970, to provide a relatively small, aerosol-type container charged with a suitable quantity of helium and arranged with a selectively operable discharge valve and attachment that will receive the ends of toy balloons whereby the balloons can be filled with helium.

To be practical, helium-filled containers of this sort must be relatively small so as to be capable of convenient use by children, and they must also contain a sufficient supply of helium to fill a reasonable quantity of balloons. Because of these practical considerations, it is necessary to charge the container with helium at a relatively high pressure, and since helium is a lighterthan-air gas, its rarefied nature presents an extremely difficult sealing problem.

In the afore-mentioned U.S. application Ser. No. l4,350, a method of sealing the container is disclosed by which a liquid sealant such as glycerol is admitted into an inverted container through the discharge valve thereof, together with the supply of helium that is to be contained. While this method of sealing provides a substantial improvement over previously known containers filled with helium, it has been found that a small percentage of containers sealed in this fashion still permit a slow leakage of helium from the container. Although the explanation of why such leakage exists is not entirely clear, it is believed that the simultaneous entry of the sealant and the helium into the container results in some disruption of the sealant at the interior surface of the container by the pressurized helium. More particularly, it is believed that the minute openings in the container through which helium may escape are not always covered by the sealant because the simultaneously entering helium tends to immediately pass through such openings and thereby preclude the sealant from having an opportunity to cover such openings. In addition, it was found that the assembly line operation for sealing and filling a container as described in the afore-mentioned application was hampered by the fact that the sealant had to be introduced through the opening in the top of the container, after which the container had to be inverted whereby helium could be admitted through the discharge valve in a manner which propagated the liquid sealant throughout the interior of the container.

In accordance with the present invention, a method of filling and sealing a container with pressurized helium is disclosed which eliminates the aforementioned drawbacks, which provides extremely reliable sealing, and which increases the efficiency of the assembly line operation by which the container is both sealed and filled.

SUMMARY OF THE INVENTION The present invention provides an assembly line operation by which a series of containers having a seamed body construction and an aerosol-type discharge valve loosely disposed at an opening at the top of the container are progressively advanced past a plurality of stations. At the initial station, the afore-mentioned discharge valve is crimped to the container body so as to generally close the opening in the container, and the container is then advanced to a second station at which the discharge valve is temporarily opened while a quantity of liquid sealant is sprayed into the interior of the container through the discharge valve. The container is then advanced to a third station at which the discharge valve is again temporarily opened to permit the container to be charged through the discharge valve with a quantity of pressurized helium. If desired, a fourth station may be provided for checking the final pressure of the helium within the container.

It will be noted that after the liquid sealant is sprayed into the interior of the container, there is a time delay as the container is being advanced to the helium-filling station. During this time delay, the liquid sealant which has been sprayed onto the interior wall surfaces of the container has an opportunity to spread evenly over the entire interior surface of the container and to thereby effectively cover any minute openings which may be present at the constructional seams of the container or at the point where the discharge valve is crimped to the container body. After this liquid sealant has had a chance to spread evenly in the afore-mentioned manner, the pressurized helium is then admitted to the interior of the container, and this pressurized helium apparently has the effect of forcing the sealant positively into any minute openings in the container so that such openings are effectively plugged by the sealant without the helium having an opportunity to pass through the opening and thereby prevent plugging by the sealant.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a front elevational view of an assembly line for carrying out the method of the present invention;

FIG. 2 is a top plan view of the assembly line shown in FIG. I;

FIG. 3 is a side elevational view of the station at which the sealant is admitted to the container; and

FIG. 4 is a view illustrating a portion of the station shown in FIG. 3 as the sealant is being admitted to the container.

DESCRIPTION OF THE PREFERRED EMBODIMENT Looking now in greater detail at the accompanying drawings, FIGS. 1 and 2 illustrate an assembly line consisting of a supply table 10 on which a plurality of containers 12 are indiscriminately disposed, the supply table 10 including a conventional mechanical arrangement by which the containers 12 are guided through a single-line channel 14 as the table 10 is rotated. The containers in the channel I4 are then individually fed onto the left-hand end of an indexing chain I6. The indexing chain 16 is endless and is carried by a support table I8 so as to have a horizontal reach presenting upstanding projections 20 uniformly spaced along the horizontal reach of the chain I6. As the containers I2 are individually fed to the indexing chain 16, the lower most flange on each container is positioned beneath two guide plates 22 (see FIG. 3), and the containers 12 are individually advanced horizontally by the projections 20 on the indexing chain 16. An electric motor and drive 24 is disposed beneath the support table 18 for driving the indexing chain 16 in intermittent fashion whereby the containers 12 are advanced progressively in predetermined increments passed four operating stations. These operating stations include a crimping station 26, a sealant supply station 28, a helium charging station 30, and a pressure checking station 32. After the containers 12 have been processed at each of the afore-mentioned stations in a manner to be described below, the finished containers 12 may be taken off the right-hand end of the indexing chain 16. Each of the containers 12 carried on the supply table has an aerosol-type discharge valve 12' (see FIG. 3) loosely disposed in an opening in the top of each container 12, and these discharge valves 12' each have a downwardly extending flange that overlaps the lip of the container opening. As each container 12 is advanced by the indexing chain 16 to a position beneath the crimping station 26, a pneumatically operated head is brought down to the container 12 and the discharge valve 12 is tightly crimped about the lip of the container opening in a conventional manner. Therefore, each container 12 leaving the crimping station 26 is in a generally sealed condition in that the top opening thereof is closed by the discharge valve 12'. However, as has been previously mentioned, helium is an extremely rarefied gas which has a tendency to leak from even the most minute openings in a container. As best seen in FIG. 3, the body portion of the containers 12 includes a vertical seam 34 as a result of the formation of the container, and in many cases this scam may include a minute opening through which helium could escape. In addition, the crimping of the discharge valve 12' to the container 12 may likewise leave one or more minute openings as a result of imperfect crimping. Accordingly, the sealing integrity of the containers 12 may not be sufficient to contain helium.

The containers 12 are then advanced to the sealant supply station 28 which is shown in greater detail in FIGS. 3 and 4. As each container 12 is moved to a position immediately adjacent the sealant supply station 28, the discharge valve 12 of the container 12 will be located directly beneath an operating head 36 as shown in FIG. 3. The sealant supply station 28 includes a trip switch (not shown) which activates the sealant supply station in response to being contacted by the container 12 as it is brought to a position beneath the operating head 36. When the sealant supply station is activated, the operating head 36 is pneumatically lowered to the position shown in FIG. 4. The mechanical details of the operating head 36 are not important in connection with the method of the present invention, and it is sufficient to understand that the operating head 36 includes a supply hose 38 through which a liquid sealant, preferably glycerol, is supplied thereto, and as the operating head 36 is moved downwardly onto the container 12, the discharge valve 12' is pressed downwardly to temporarily open the discharge valve 12' whereupon the glycerol is admitted into the container from a small orifice in the operating head and through the discharge valve 12'. The glycerol is admitted into the container under pressure whereby it is propagated as a spray within the confines of the container 12. As a result, the entire interior surface of the container 12 has applied thereto a film of glycerol. It is well known, of course, that glycerol is a surfactant having high surface tension characteristics which renders it suitable as a sealant.

After the container 12 leaves the sealant supply station 28, it is advanced in progressive increments to the helium charging station 30, and as it is being thus advanced, the glycerol which has been sprayed into the container 12 has an opportunity to spread evenly over the entire interior surface of the container 12, particularly in the areas of the vertical seam 34 and the flanges resulting from the manufacturing techniques of forming the container 12.

The helium charging station 30 includes a mechanical arrangement which is identical to the previously described sealant supply station 28, and as the container 12 is brought to a position adjacent the helium charging station 30, an operating head is pneumatically lowered to again temporarily open the discharge valve 12' whereupon the container is charged with a supply of helium, preferably at a pressure of p.s.i. to I60 p.s.i. Because of the time delay in advancing the container from the sealant supply station 28 to the helium charging station 30, and the fact that the glycerol has had an opportunity to spread evenly over the interior surfaces of the container 12, the container 12 is effectively sealed when it reaches the helium charging station 30. Moreover, if the container 12 originally contained some minute openings therein, these openings will be covered by the glycerol and the pressurized helium will then act to force the sealant directly into such minute openings whereby there will be a concentration of sealant at such openings to further enhance the sealing capability of the glycerol.

After the container 12 leaves the helium charging station 30, it is advanced to the pressure checking station 32 which also includes an operating head identical to the operating head 36 described previously in connection with the sealant supply station 28. The pressure checking station 32 includes a pressure indicating valve 40 which allows the operator to visibly confirm that the pressure of the helium within the container 12 is within the afore-mentioned desired range.

Thus, the present invention provides a fully automatic assembly line operation which results in the con-- tainers 12 being generally sealed at the crimping station 26 and then completely sealed at the sealant supply station 28, after which the container is fully charged with a supply of helium at the helium charging station 30. The result is a container 12 which is fully charged with a desired supply of helium and which is completely sealed against leakage whereby the container 12 will have an extraordinarily long shelf life eventhough an inexpensive container construction is used and eventhough the contained gas is extremely rarefied.

The present invention has been described in detail above for purposes of illustration only and is not intended to be limited by this description or otherwise to exclude any variation or equivalent arrangement that would be apparent from, or reasonably suggested by, the foregoing disclosure to the skill of the art.

I claim:

1. A method of automatically sealing and filling a container having a seamed body construction and having an aerosol discharge valve loosely disposed at an opening in an end wall of said container, said method including the steps of progressively advancing said container along as assembly line in stepped increments, crimping said discharge valve to said container body to close said opening therein, temporarily opening said discharge valve while spraying a supply of liquid sealant downwardly into said container through said open discharge valve to coat the interior surface of said container with a thin layer of said sealant, and then temporarily reopening said discharge valve while charging said container through said open discharge valve with a supply of pressurized lighter-than-air gas.

2. A method of automatically sealing and filling a container as defined in claim 1, and further characterized in that said liquid sealant is glycerol, and in that said lighter-than-air gas is helium.