US2471332A - Method of sealing empty cans - Google Patents

Description

May24, 1949. p.1 LEMMEL 2,471,332

METHOD OF SEALINGv EMPTY CANS Filed June 28, 1944 r 2 Sheets-Sheet l 5 I l' i 5 41) 4; $94. 1v z z y 0 15 7 7 PAUL HTTORNEX 5*; 24, 1 P. T. LEMMEL METHOD OF SEALING" EMPTY CANS 2 Sheets-Sheet 2 Filed June 28, 1944 N 55 m x 5 b m 55 U u H u n u .u J R MM 5 5.5 V F\ \q 25252252255 W BY PAUL T. LE'MMEL 14 TTUAIVE Y.

Patented May 24, 1949 METHOD OF SEALING EMPTY CANS Paul T. Lemme], Madison, Wis., assignor to The Borden Company, New York, N. Y., a corporation of New Jersey Application June 28, 1944, Serial No. 542,526

2 Claims. 1

This invention relates to a method of treating cans which are intended to be utilized subsequently in the storage of food products, and to new and improved apparatus for accomplishing this treatment. More particularly, it relates to a new and improved method whereby cans made from tin plate which are intended for use in the packaging of liquid food products such as evaporated or condensed milk may be maintained in sanitary and uncontaminated condition during storage, and until such time as the cans are filled and sealed.

My invention is also concerned with apparatus whereby the tin cans may be treated, subsequent to their manufacture, in order that they may be subsequently stored without danger of contamination until they are filled with the condensed or evaporated milk product. The invention also relates to apparatus by which a sealing material, applied to the filling apertures of the tin cans after manufacture and before filling, may be completely and effectively removed so as to permit the application of a leak-proof solder seal to the aperture.

In manufacturing tin cans of the type utilized for storing food products, can top and bottom elements are soldered to the cylindrical can body.

One of the circular end sections used to form the can top is ordinarily punched during the forming operation to provide an aperture for later filling the can. The manufacturing process is the same regardless of the particular shape of the cans, although cans used for packaging evaporated or condensed milk are usually cylindrical in form. The empty can may then be stored before being shipped to the food processer and, after its arrival at the canning factory, the can is usually stored again for a period of time before being filled with milk or other food product to be packaged therein.

Although the empty can is sterilized by passage through molten solder during the process of attaching the can top and bottom to the can body, it loses its sterile condition during subsequent storage. Access to the interior of the can is easily possible through the filling hole punched in the top section, and bacterial life and other contaminating microorganisms, as well as dirt, may readily enter the can. Moreover, the hole in the can top is usually punched so that a numher of depending sharp-edged portions or prongs project down into the interior of the can. During the storage period not only is it possible for bacteria and other microorganisms to grow and develop on these edge portions but, due to removal of tin plate and exposure of the bare metal in the punching operation in which the hole is formed,.th-e edge portions thereof may become rusted or corroded to a greater or less degree. The can, although sterile when made, is therefore no longer sterile at the time it is filled with evaporated milk or other food product to be stored therein. Subsequent treatment, such as by heating to an elevated temperature to destroy bacterial life and to restore the sterility of the empty can, is generally impractical at this stage. In any event, the corroded surfaces on the prongs of metal surrounding the hole and extending down into theinterior of the can introduce a foreign substance into the packaged product. Soldering to provide a tight seal is, moreover, rendered difl'icult because of the corroded portions adjacent the'filling hole.

It is, accordingly, the primary object of this invention to prepare and treat empty cans subsequent to manufacture in such a way that they remain in substantially clean and sterile condition for an indefinite period of time until the food product is placed therein and the can sealed by the application of flux and solder to the filling opening in the usual manner. It is another object of this invention to treat empty metal food containers, after their manufacture, in such a way that microorganisms, dirt, dust, and other contaminating agents are prevented from gaining access to the interior of the can through the opening provided for filling. Still another object of this invention is to treat the empty can in such a manner that the depending sharp-edged portions or prongs of metal forced into the interior of the can by the hole-punching operation are prevented from corroding or rusting during storage, the entry of dirt, dust, or contaminating microorganisms into the can being also prevented by the same treatment.

Further objects of this invention include the provision of apparatus by which empty cans, prior to storage but subsequent to their manufacture, may be treated'in order to accomplish the objects previously enumerated. In the accomplishment of these objects I provide apparatus by which empty cans which have been stored in sanitary condition may be treated to render them ready for filling with liquid milk or other food product to be packaged therein. The foregoing, as well as other aims of my invention, will be apparent from the ensuing disclosure of certain preferred embodiments thereof.

I have found that these objects may be attained by sealing the hole punched in the can top with a plug of paraffin, or with a plug of paraflin and wax, this plug remaining therein during storage, and; remoyedionly when the can is to be filled with the-food product. While'I prefer to utilize parafiin, or a mixture of parafiin and wax,

other waxy compositions capable of being melted and removed by the applicationot heatare suit-- able for use in my process.

In the treatment of empty-"can bodies" in. ac.- cordance with my process If utilize emptymetal food containers provided with bottom and top portions soldered to the cylindrical. section; These empty cans, provided with a punched hole in one end portion thereof, are ordinarily" ina sterile and sanitary condition at the completion ofe the: manufacturing.operatioms As: previously explained bacterial; life: anch other. microorganisms are destroyed: by the"; high; temperatures maintained during: the soldering! process, and. the empty can is ordinarily: clean andi free; from. dirt or contaminatinga material: whom it. is. shipped. from the factory; Itis.airthisstagewthat I-treat the empty can inrorderrtp preserve that cleanliness and freedom.fromvccntaminating micro.- organisms' until it is. ready to, he: filled.

The empty can is treatedrin:- accordance with my process, byth applicatiom thereto of sufiicient paraifim. or sufiicienizsofi a; mixture of paraiiin. and? Wax, so thatwhen theaparaflinor paraflin -wax. composition; cnngeals; the hole will be completely. closed, and-1 the: edge portions. or prongs: f v metal: surroundingthe.- hole. and depending. withirrv the: body; ofilthe; can completely protected by the? coating; (Inrrosion off these metaifprongsis; alsoipreyented by. this treatment. The. plug of? paraffiinor of' ai parafiin-wax: mixture, may' bearea'dilyrihtroduced; by. applyin molten panaflim. on moitem panaflinewax: mixture, directly to the hole}. either permitting it to now. therein, or. by: applying-pith 11188118301 a plunger; The plug; of; paraifin'fland .waxthen solidifies in; the hole-,, thereby;,-forming1 a closure seal, aswell; as protecting-the prongs; of: metal extending below the; hole; When the: cans are stored, either at--the; can; manufacturin plant or priorto,fi1ling;,a,t;the;;canning plant-,they remain in substantialiy q sterila condition because the-seal formedbywthe paraffinzplug' prevents micro-organisma;dirt,,--and contaminating: matter fromfinding itszway'intothercan.

When the empty .cans-areready-tobe filled with liquid milk or,otherwfoodyproducts, suchI as for eXample, evaporated or'ccndensed, milk,,or other milk or cream product; the paraffin or paraffin-wax plug, isheated, sufiicientlyto melt it at those portions where: it: contacts, theedges of the filling hole. ,Theair within'the empty can is simultaneously caused-to. expand -by the action. of the-heat. This, results inthe wax plug being driven out, or forced out, of. the filling holeby pressure-ofthe heated air.

To insure the removaror. all.- Of -.the paraffin or. parafiin-wax sealing material the area. adjacentthe holemay then/benfurther heated, as y. the. application. of a. gas.,fiame. theretoor by other heating means. This causes any sealing material which still adheres to the metal to melt and run off, thus insuring complete removal of any small particles of the parafiin or paraffinwar: mixture remaining.

Instead of removing the sealing plug by the application of heat alone, it may be removed by the application of heat sufficient to melt the paraffin or paraffin-wax plug at the edge portions of the aperture, followed by the application of vacuum means or suction. When applying suction means in combination with heating it will ordinarily not be; necessary to: heat the empty cans adjacent the hole in order to melt and remove the remaining particles of sealing material, although, if desired, this step may be included inboth methodsin order to insure complete freedom of the can prior to filling from any foreign material which might endanger the purity of the packagedproduct.

The can is then filled with the food product and. sealed in the usual manner. In the case of evaporated or condensed milk, this may involve, for example, filling the can from a spigot or other supply source with the milk product, excess milk being then blown off the top-of the can by means of a jet of steam or air.. A gas.- jet, or other heating device, may, then be. applied to the top ofthe can, and flux applied adjacent the hole by hand, by means of a reciprocating sponge or brush device, orby any other-suitable mechanism. Solder is applied toseal the hole,,soldering being suitably accomplishedbyrthe use of an iron which iscleaned-each time it is. applied. to. a can by means ofsalammoniac. or other fluxing material. The sealed can is then heated to.- sterilize its contents, and it may be stored or. shipped. to the consumer. with complete assurance, as to the purity. of the packaged. food. product.

Theannexed drawing disclosesapparatus suit.- ablefor applying the. closure plug. of paraffin or paraffin-Wax mixture tofthe, empty can body, and apparatus for removing that plug at the conclusion of. the storage periodbefore filling. the empty can with milk or other food product to be packaged. therein. In these drawings:

Fig, 1, is a cross-sectional view of part of an empty can showing the filling hole punched in the can top;

Fig. 2 is a cross-sectional view of a portion off the. empty can showing the punched hole of Fig. 1 sealed or closed, in accordance With my method',.wi.th a closure plug of parafiin or paraffin-Wax mixture;

Fig. 3115 an elevationaljvi'ew of an apparatus capable of supplying a moltenparafiin, or molten paraffin-wax mixture, to the aperture in the can end section for the purpose of sealing the same;

Fig. i. is a diagrammatic view in plan of the apparatus shown in Fig. 3;

5 is an eleyational. View of. apparatus for removing the paraffin or paraffin-Wax plug from the hole in the can top atv the conclusion of storage, prior to, filling the, empty can with. the food product to be packaged therein;vv and.

Fig. 6 is a. plan, View of. the. plug-removing echanism shoWn-inFigfi.

Referring more particularly to-Figs. 1 and 2, the'numeral i denotes. generally a. tin can provided. with. can. top 8, which. is ordinarily circular inshape but maybe. of square, rectangular, elliptical or other shape.- This. can. top is provided, as shown, with punched hole-0r aperture 97 formed by forcing a punching. toolthrough the. metal, generallybefore. the topis soldered to the cylindrical side Walls of the can body 1. In the punching operation depending flanges or prongs of cut metal I 0 are forced to one side of the can top 8 and, when the can is assembled, they project into the empty can.

Fig. 2 shows the plug of parafiin or paraffin- WaX mixture H in place in'the filling. aperture 9 of the can i. As shown in the figure, not only does the paraflin or parafiin-wax plug ii completely seal the opening 9, preventing access to the interior of the can, but it also serves to coat the cut edges of depending flanges or prongs 10, thereby preventing corrosion or rusting of these out edges during the storage period. Ordinarily the protective coating of palm oil or other oleaginous material on the tin plate used to form the can is torn off or removed by the punching operation, so that unless these out edges were protected rusting and corrosion would rapidly follow. .As shown in Figs. 1 and 2, the can top 8, as usual in the manufacture of cans, is soldered to the cylindrical portion of the can body at l2.

Referring to Figs. v3 and 4, the empty cans 1 provided with filling hole or aperture 9 are transferred from transfer wheel 54 to star wheel i5. These wheels are positively rotated by the application of suitable power means, not shown, the wheels being rotated in the directions indicated. To assist in the transfer there are provided guides i6 and I"! to guide the empty cans.

Guide I! is provided with arcuate portion l9, supported at one end at support 26 and capable of being adjusted by means of adjustment means 2!. By suitably adjusting arcuate guide !9 empty cans 1 may be readily transferred to receptor sections 22 of star wheel 15.

Guides 23 and 24 are also provided, the latter constituting a continuation of arcuate guide l9 and being supported at its end portion by support 2i Supporting member 25 for guide I6 is also provided. The direction of travel of the can bodies as they move from the transfer wheel Hi to the star wheel 15, and as they leave the star wheel, is indicated by the arrows on Fig. 4.

Over one portion of the star wheel there is provided, as shown, conduit 2'! for the molten parafiin or paraffin-wax mixture, this conduit being provided with nozzle or spigot 28 adapted to supply molten paraffin or paraffin-wax directly to the punched aperture 9 in the can top section 8. Suitable means, not shown, may be employed for regulating the amount of the molten sealing material applied to each particular can so that just suficient is supplied to provide, on cooling, the solid plug ll positioned in the filling opening 9 and serving to coat and protect the metal prongs It) against corrosion.

Prior to filling the can with milk or other food product it is necessary to remove the closure plug. An apparatus for removing the closure plug is shown in Figs. 5 and 6, although other forms of apparatus, especially those employing heat to melt the paraffin or paraffin-wax mixture slightly adjacent the edges of hole 9 combined with suction means to remove the plug by positive suction, may also be utilized.

Referring more particularly to the type of apparatus shown in Figs. 5 and 6, it will be noted that the can bodies I with end sections 8 and sealing plugs I l in apertures 9 are allowed to roll downwardly on the guide member or ramp 30 onto supporting member 3|. They are rolled along this supporting member 3| by the action of the conveyor belt 32, which is positively driven in the direction of the arrow, travelling around pulleys 33 and 34. The lower reach 320 of the belt 32 contacts the cylindrical side portions of the empty cans l, the cans being rolled along guidewa or supporting surfaces with rails 3|.

As shown in Fig. 6, bearing 36 and 3'! are provided for the axles 39 and 40 of supporting pulleys 33 and 34, these axles being, in turn, supported from brackets 4| and 42 which are suitably attached at 44 and 45 to the structure of can supporting surfaces 3 l.

Positioned above the can bodies as they roll along the guideway or supporting surface 3|, ad jacent the lower reach 32a of the endless conveyor belt 32, is the heating means with manifold M, supplying a number of gas jets 48, gas being supplied thereto by conduit 49. These gas jets serve to heat the air contained within the empty can bodies and sealed therein since plug H is in place in the aperture 9. At the same time that portion of the plug of paraffin or paraffin-wax mixture adjacent the prongs or edge portions i!) of the aperture 9 is heated by heat transmitted through the metal can and caused to melt, so that the plug no longer tightly adheres to the depending prongs it! of the aperture 9. As the air within the can 'i is heated it expands and, due to the release of the plug from the hole 9 and from depending prongs ID, the plug is positively forced out by the action of the air. In this way the sealing plug is caused to pop out, i. e., forced out under the combined action of heat and air expansion, thus providing access to the interior of the can for filling.

In order to insure complete removal of all traces of the paraffin or paraffin-wax sealing composition, thereby preventing the introduction of any foreign material into the packaged food product, a second heating means including manifold 5! may be provided. This heating means may include a plurality of gas jets 52 supplied through conduit 53, which gas jets impinge against the can end sections 8 at the portions thereof adjacent apertures 9. These gas jets serve to melt the remaining traces of paraffin or paraffin-wax mixture, which drops off from the can covers, leaving the cans completely sanitary and free from any foreign material. As the can blanks emerge from the guideway 3| onto the ramp or guide 55 they are in readiness for filling with evaporated milk, condensed milk, or other food product to be packaged therein. At this stage they are completely sanitary and uncorroded, regardless of the period of time that they may have been in storage subsequent to their manufacture.

It should be understood that although my invention has been described with particular reference to certain preferred embodiments thereof, various changes and modifications may be made therein within the spirit of the invention. It is therefore to be construed as including such modifications and variations as are within the scope of the appended claims.

I claim:

1. The process of treating empty plated metal cans having an aperture therein adapted for the introduction of a food product therein, the edges thereof forming said aperture being unplated, said process comprising filling said aperture com pletely and covering said edges completely witha plug of waxy material whereby the interior of said can remains in a substantially clean and sterile condition and the corrosion of said edges is prevented during storage, and removing said plug prior to filling said can with a food product.

2.- The: proeess-l ofi tneatin'g empty plated; metal cansahaving amapentureutherein adapted for the intmduotion ofiithe food: product therein, the edges .zrthereufiforming; said; aperture being un,- piatedasa'id pnoscess' comprising, filling; said.v aperture'icompletelyt and; covering said edges: come pletelyrwitn a-.plug of- ,Waxymaterial-1 whereby the interionqof said. can remains in a substantially cleamand sterile condition and the corrosion, of said edges is prevented duringjistor-age; heating said cam priorto filling sufficiently to melt said plug and:removing; substantially; completely all ofi 'therwaxy material, from; saidvcanz PAUL.v T. LEMMELr I REEERENGES? CITED The; following. references areof' record inthe file of this. patent;

6 UNITED: STATES PATENTS Number Name Date 1,969,724 Brooks Aug. 14, 1934 2; 092g4'44 Doulgheridis Sept. 7, 1937 lm 2,355,073 Hothersall Aug. 8, 1944

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