US2479959A

US2479959A - Method of applying protective spots to the pads of closure caps

Info

Publication number: US2479959A
Application number: US756373A
Authority: US
Inventors: James H O'neil
Original assignee: Continental Can Co Inc
Current assignee: Continental Can Co Inc
Priority date: 1947-06-23
Filing date: 1947-06-23
Publication date: 1949-08-23
Anticipated expiration: 1966-08-23

Description

2,479,959 TIVE SPOTS E CAPS J. H. ONEIL METHOD OF APPLYING PROTEC TO THE PADS OF CLOSUR Aug. 23, 1949.

3 Sheets-Sheet 1 Filed June 23, 1947 A 6 m 9 v James H.0'Nei1 M, an, 99 9 (Incl-mus A g. 23, 1949. J. H. ONEIL 2,479,959

METHOD OF APPLYING PROTECTIVE SPQTS TO THE PADS 0F CLOSURE CAPS Flled June 23, 1947 3 sheets sheet 2 FiG.9

FicaAO 26 2.6 26 26 F l (*1 4 r' l r-1 I l I 1 (16 16 16 16 Bum-"tor James 5.0 Neil Gttornejs Aug. 23, 1949. J. H. O'NEIL 2,479,959

METHOD OF APPLYING PROTECTIVE SPQTS TO THE PADS 0F CLOSURE CAPS Filed June 23, 1947 3 Sheets-Sheet s 15 15 T v T Fie.14- 33 31 f 1+ 33 my d A l x j \W l V I 30 -11 INVENTOR. James H.0Nei1 BY M G n-A7,, bal YW ATTORN EYS.

Patented Aug. 23, 1949 METHOD OF APPLYING PROTECTIVE SPOTS I TO THE PADS OF CLOSURE CAPS James H. ONeil, Syracuse, N. Y., a'ssignor to Continental Can Company, Inc., New York, N. Y., a corporation of New York Application June 23, 1947, Serial No. 756,373

6 Claims. 1

me invention relates to new and useful improvements in a method of applying a protective spot to the pad of a closure cap and more particularly a metal foil spot which is attached to the pad by a thermoplastic adhesive.

An object of the invention is to provide a method of the above type wherein the adhesive is rendered tacky by passing an electric current through the metal foil.

Another object of the invention is to provide a method of the above type wherein the adhesive is rendered tacky by contacting the metal foil at spaced points with electrical conductors and passing an electric current through the metal foil from one point of contact to the other.

A further object of the invention is to provide a method of the above type wherein the spot is placed in centered relation to the pad to which it is to be attached, after which the adhesive is rendered tacky by passing an electric current through the metal foil.

A still further object of the invention is to provide a method of the above type wherein the metal foil has a thermoplastic adhesive applied thereto and wherein the adhesive side of the spot is placed in contact with the pad of the cap and then the adhesive rendered tacky by passing an electric current through the metal foil.

Another object of the invention is to provide a method of the above type wherein the spot with the adhesive applied thereto is placed in contact with the plunger which is to press the spot against the pad and then the adhesive is rendered tacky by passing an electric current through the metal foil while it is in contact with the plunger.

A further object of the invention is to provide a method. of the above type wherein the spot with the adhesive applied thereto is placed in a carrier for conveying the same from the forming station to the station where the spot is attached to the pad, and wherein the adhesive is rendered tacky while on the carrier by passing an electric current through the foil.

A still further object of the invention is to provide an improved and novel arrangement whereby a thermoplastic bonding agent may be softened by the application of heat for attaching a metal foil spot to a pad in a crown shell, and wherein the application of the heat may be localized and more readily controlled than is possible when the spot or cushion is heated by conventional methods, by contact with an open flame, or by contact with a heated plunger.

Another object of the invention is to provide a method of the above type wherein the metal toil spot is heated by passing an electric current through the metal foil, and attaching the foil spot to a closure pad having a thermoplastic surface.

A further object of the invention is to provide a method of the above types wherein an uncoated foil spot is heated by passing an electric current through the metal foil and placing the heated spot in centered relation to a pad having an ad- 'hesive surface and pressing the heated spot against the pad to render the adhesive tacky and adhere the spot to the pad.

In the drawings, there is shown more or less diagrammatically a form of apparatus that could be used in carrying out the improved method and a closure cap made thereby.

Figure 1 is a sectional view through the cap containing a pad and a metal foil spot attached thereto;

Figure 2 is a vertical sectional view through a carrier for the spot and the punching mechanism for cutting a spot from a strip of spotting material;

Figure 3 is a similar view but showing the spot as cut and the ejector having stripped the spot from the die into the carrier;

Figure 4 is a vertical sectional view through an assembling unit which includes a plunger, a support for the closure cap and the carrier, said carrier being in centered relation to the cap so that the spot may be stripped therefrom and properly positioned on the pad;

Figure 5 is a view similar to, Figure l but show-- ing the plunger as moved down into contact with the spot preparatory to the stripping of the same from the carrier;

Figure 6 is a view similar to Figure 4, but showing the plunger as having stripped the spot from the carrier and as pressing the spot against the pad of the cap;

Figure 7 is a side view of the plunger showing the contacting elements for directing an electric current through the metal foil and the electrical connections associated therewith;

Figure 8 is a bottom end view of the plunger shown in Figure 7;

Figure 9 is a view, similar to Figure 7, of r plunger, but showing a slightly modified arrange ment of contacting elements for directing an electric current through the metal foil;

Figure 10 is an end view of the plunger shown in Figure 9;

Figure 11 is a diagrammatic view showing a means for supplying electric current to the contacts associated with the plunger in a single unit machine;

Figure 12 is a diagrammatic view showing a series of plungers with the electric contacts associated therewith connected in series;

Figure 13 is a view partly in plan and partly in section of a carrier for the spot showing a means associated therewith for heating the foil while in the carrier;

Figure 14 is a sectional view on the line H-Hl of Figure 13; and

Figure 15 is a sectional view on the line I--l5 of Figure 13.

It is a common expedient .to provide a closure cap for containers with a sealing pad which spans the mouth of the container and to apply to the inner face of the pad a protective spot, which spot is of smaller diameter than the pad but of suificient size to prevent the contents of the container from contacting with the pad.

The present invention has to do with a novel method of attaching the protective spot to the pad of the closure cap of the above type. The cap may be of any desired construction and of any suitable material. For the purpose of illustration, a well known crown cap is shown which consists of the metal top I having a skirt 2 which is corrugated and adapted to be crimped beneath a shoulder on the container for securing the cap thereto. Located within the cap is a pad 3 which is preferably made of a cork composition. The protective spot consists of a foil base or facing member 4 to which is applied a coating 5 of any suitable thermo-plastic adhesive.

The adhesive coating 5 according to the improved method is heated by passing an electrical current through the metal foil 4. The spot is first cut and it is then placed in a carrier. The carrier conveys the spot to a station for application to the pad of the cap. The electric current is passed through the foil either at the assembling station or while it is being conveyed by the carrier and for a time sufiicient to render the adhesive tacky. The tacky adhesive is pressed against the pad and held there until the adhesive cools so as to bond the spot to the pad. The electric heating current will of course be cut off so as to permit the cooling and bonding of the spot to the pad. It is believed the invention will be better understood by a brief reference to the illustrated apparatus which may beb utilized in carrying out the method.

The foil is preferably made in strip form and the thermoplastic coating is applied to one face of the foil strip. As shown in Figure 2, the foil strip is indicated at 6. Said strip-is of slightly greater width than the diameter of the spot to be cut therefrom. The strip is passed between a die I and a stripper plate 8. The punch 9 is moved through the plate 8 into contact with the foil strip 6 and cuts therefrom a spot. An ejector I0 is timed so as to move into contact with the spot after it has been cut by the punch and this ejector will force the spot indicated at H from the die I into a carrier l2 which has been placed in centered relation relative to the die. This carrier 12 is provided with a sleeve l3 of insulating material and on the inner face of the sleeve are barbs M which taper from the central portion thereof upwardly and downwardly. These barbs are very small and serve solely as a friction means for holding the spot in the carrier. The ejector carries the spot from the die into the sleeve of the carrier to a point midway the upper and lower extremities of the barbs. After the spot has been loaded in the carrier, then the carrier is moved to a position where the spot will be centered over the pad I in a cap I. The closure cap is shown as carried on a support i5. Suitable means is associated with the support for placing the cap in a pre-determined fixed position for receiving the spot. As noted, the carrier I2 is centered over the cap. Directly above the support for the cap is a plunger Hi. This plunger is guided in a suitable frame structure indicated at I! and there is a sleeve of insulating material l8 between the supporting frame structure and the plunger.

The plunger, as shown more clearly in Figures '7 and-8, consists of a central portion l9 which may be of any suitable material. There are segmental recesses formed in the plunger which extend from one end thereof to the other. Located in the recess at the right, as shown in Figure 8, is a conductor element 20. Between the conductor element and the main portion i9 is an insulating material 21. On the opposite side of the plunger is a conductor element 22 and insulating material 23. The

conductors

20 and 22 are shaped and sized so that they lie within the cylindrical outer surface of the plunger. The conductor element 20 is connected to a suitable current supply by a line 24 and the conductor element 22 is connected to a line 25. These lines are connected to a transformer indicated at T and include a variable resistance R, by which the amount of current can be varied to the extent necessary to heat the spot in the desired time. There is a suitable switch (not shown) in the current supply which controls the flow of current to the conductor elements.

The plunger I6, as noted above, is centered relative to the carrier l2 and when moved downward will move into the sleeve I3 of the carrier and contact the spot II. The support for the cap 5 is raised so as to bring the cap into engagement with the lower portion of the sleeve l3. Said lower portion is tapered so as to insure the centering of the cap relative to the sleeve. The plunger as it continues its movement will strip the spot from the barbs and place it against the pad in centered relation thereon, as shown in Figure 6.

In the preferred form of the novel method, the plunger presses the spot against the pad after which the switch is closed and a current will pass from one of the conductor elements through the foil to the other, as indicated in the broken line and the arrows in Figure 1. The foil, of course, offers resistance to the flow of the current and this results in a heating of the foil and the heated foil imparts heat to the adhesive so as to render it tacky. The heat imparted to the adhesive will also be imparted to the surface portion of the pad and this will facilitate the bonding of the spot to the pad. After the adhesive has been rendered tacky so as to be bonded to the pad, the current is cut off and the plunger will remain in contact with the spot until the adhesive has been set sufliciently to retain the spot on the pad.

Another manner of heating the foil consists in the pressing of the spot lightly against the pad, then passing a current through the metal foil to heat the foil and thereby the adhesive until it is rendered tacky, and then movin the plunger so as to firmly press the spot into intimate contact with the pad.

Another manner of heating the foil consists in the turning on of the current when the spot is in contact with the plunger and while in the carrier, as shown in Figure 5. In this view, the cap has been centered by the carrier ready to receive the spot but the current from the conductor elements is passed through the foil while in contact with the plunger and while out of contact with the pad. This will render the adhesive tacky and then the plunger will move the spot from the carrier and press it against the pad for the bonding of the spot to the pad.

A still further method of heating the adhesive consists in providing a means for passing an electric current through the foil spot while it is in the carrier. In Figures 13 and 14, the carrier 1 is shown as mounted on a movable member 29. This movable member presents the carrier to a punching station where the foil spot is formed and placed in the carrier and then it presents the spot to the assembling station where the spot is placed against the pad and secured thereto.

As shown in these figures, the foil is electrically heated while on the carrier and may be heated While the carrier is moving from the punching station to the assembling station or heated' at the assembling station. The carrier 1 has embedded therein two

segmental conductors

30 and 30 The barbs M, l 4 are formed integral with these segmental conductors. Between the conductors which are spaced from each other are barbs l4 similar to those described above, and it is these barbs which hold the spot in the carrier until it is stripped therefrom by the plunger. The carrier "i is made of insulating material. Each segmental conductor is provided with a radially projecting portion 3! and these projecting portions carry

heads

32, 32 which engage

contact bars

33, 33 respectively, as the carrier moves 1 along its path to the plunger or at the assembling station. Thus it is that current is passed from the contact bars to the segmental conductors and through the foil. If the foil has been heated, it may be used to heat the adhesive, and render it tacky so that when the foil spot is pressed against the pad of the cap, it will be secured thereto.

This heating of the spot may take place either after or before the carrier has moved the spot into centered relation relative to the pad. In other Words, while the spot is moving from the punching station to the assembling station, current may be passed through the foil and the adhesive rendered tacky.

The plunger as shown in Figures 9 and 10 is similar to that shown in Figure '7. except that one of the conductor elements is in the form of a cylindrical'sleeve 26, while the other conductor element is in the form of a rod 21. The rod is located centrally of the plunger and the conductor sleeve encircles the plunger. The plunger in this case would be of insulating material, as indicated at 28. The conductor element 26 is connected to the line 25 and the conductor element 2! is connected to the line 26. The manner of heating the foil will be the same as described above.

It will be understood that other arrangements of the conductor elements may be employed. It is essential, however, that these conductor elements may contact with the foil side of the spot at spaced intervals so as to direct current into and through the foil from one conductor element to the other.

In order to speed the productiomit is often desirable to provide a strip of spotting material which is or sufiicieut width so that a gang of punches may cut from the strip a plurality oi spots at the same time. The carrier will also have the same number of sleeves to receive the individual spots as they are cut and the plungers will be of a similar construction and all move simultaneously for stripping the spots for the carrier and placing them on the pads.

In Figure 12, there are shown five plungers, I6, I6 I6 l6 and I6. The conducting elements on the plungers are all connected in series by lines 26. One of the conductors of the plunger i6 is connected to one side of the transformer and the conductor of the plunger I6 is connected to the opposite side thereof.

The resistance of the metal foil is such that a source of low voltage, high amperage current will cause the required current to pass through the foil. The amperage of the current should be sufficiently high to heat the foil and the adhesive to render the adhesive quickly tacky.

Experiments have demonstrated that a conventional adhesive coated aluminum foil spot, when pressed against a cork cushion, could be heated to the required temperature to render the adhesive tacky in four seconds by the lateral passage of 36 amperes through the metal foil and after the spot had cooled and the pressure released a commercially acceptable bond was made between the foil and the pad.

Spots cut from uniform material will have a. uniform electrical resistance. The heat developed by a current passing through a given resistance is proportional to the time and the square of the current. Therefore, the time to heat the spot to a given temperature can be altered by simply increasing or decreasing the current. For example, when 36 amperes will heat the spot in four seconds, 41.6 amperes will heat it in three seconds, and 50.9 amperes will heat it in two seconds.

In order to avoid burning of the foil, the conductor elements should be placed in contact with the foil spot before the switch is closed. Likewise, the current should be cut oil before the conductor elements are lifted from the foil so as to avoid arcing and burning of the foil. Furthermore. when the foil is heated while in contact with the plunger and the pad, the plunger should be held in contact with the spot after the current is cut an a sufficient time to permit the adhesive to cool and set sufiiciently to hold the spot in contact with the pad.

The method as described above is particularly applicable to a foil spot wherein a thermoplastic adhesive is placed on the strip from which the spot is formed and becomes an integral unit with the foil spot. From certain aspects of the invention, the thermoplastic adhesive may be placed in spot form on the pad or the paditself may be made of a thermoplastic material. The toll would, of course, then be separately heated, and,

while not pressed against the thermoplastic adhesive constituting the pad or coat on the pad and thus bring about the adhering of the foil to the pad.

The apparatus shown and described is purely for the purpose of illustrating the essential steps in the improved method of heating the foil for rendering the adhesive tacky and it will be understood that the method may be employed in various forms and arrangements of devices for carrying out the same.

It is also obvious that modifications in the method of using the principle of heating the adhesive to render it tacky by passing electric current through the foil to heat the same may be made without departing from the spirit of the invention as set forth in the appended claims.

I claim:

1. The method of attaching metal foil spots having a thermoplastic adhesive coating to a pad of a closure cap comprising passing an electric current through the metal foil for a time sufllcient to heat the foil until the adhesive becomes tacky and pressing the spot against the pad while the adhesive is tacky.

2. The method of attaching a metal foil spot having a thermoplastic adhesive coating to the pad of a closure cap comprising placing conductor elements in contact with the metal at spaced in-. tervals and then passing an electric current through the conducting elements and through the foil for a time suflicient to heat the foil and render the adhesive tacky cutting off the current and pressing the spot against the pad while the adhesive is tacky and holding the spot pressed against the pad until the adhesive sets sufficiently to bond the spot to the pad.

3. The method of attaching a metal foil spot having a thermoplastic adhesive coating to the pad of a closure cap comprising forming a spot of metal foil having a thermoplastic adhesive coating on the inner face thereof, pressing the formed spot against the pad of a cap and heating the thermoplastic adhesive by passing an electric current through the metal foil for a time sufilcient to heat the foil until the adhesive becomes tacky.

4. The method of attaching a metal foil spot having a thermoplastic adhesive coating to the pad of a closure cap comprising forming a spot of metal foil having a thermoplastic adhesive coating on the inner face thereof, pressing the formed spot against the pad of a cap and heating the thermoplastic adhesive by passing an electric current through the metal foil for a time sufilcient to heat the foil until the adhesive becomes tacky, and thereafter cutting oil the current to permit the foil and adhesive to cool.

5. The method of attaching a metal foil spot having a thermoplastic adhesive coating to the pad of a closure cap comprising forming a spot of metal foil having a thermoplastic adhesive coating on the face thereof, pressing the spot lightly against the pad, passing an electric current through the metal foil for a time sumcient to heat the foil until the adhesive becomes tacky and then pressing the spot into intimate contact with the pad.

6. The method of attaching a metal foil spot having a thermoplastic adhesive coating to the pad of a closure cap comprising forming a spot of metal foil having a thermoplastic adhesive on one face thereof, passing an electric current through the metal foil for a time suflicient to heat the foil until the adhesive becomes tacky while the spot is centered relative to the pad and spaced therefrom, then moving the spot into contact with the pad and holding it against the pad until the adhesive bonds the spot to the pad.

JAMES H. ONEIL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,788,260 Warth Jan. 6, 1931