US2778175A - Method of sealing containers - Google Patents

Description

Jan. 22, 1957 w.H. BRYCE METHOD oF SEALING CONTAINERS 4 Sheets-Sheet l Filed NOV. l, 1950 mw'. Q

l Mza/AM e@ yc@ Q BY f l E HII El ATTORNEYSA Jan. 22, 1957 w. H. BRYCE METHOD OF' SEALING CONTAINERS 4 Sheets-Sheet 2 i INVENTOR. W/z/AM 2V. A? Y Filed Nov. l 1950 Jan. 22, 1957 w. H. BRYCE 2,778,175

METHOD OF SEALING CONTAINERS Filed Nov. l, 1950 4 Sheets-Sheet 3 ww N JNVENTOR. W/l/A/V H. Bf? VCE,

Jan 22, 1957 w. H. BRYCE METHOD OF' SEALING CONTAINERS 4 Sheets-Sheet 4 Filed NOV. l, 1950 1N V EN 710K. e@ vof,

ATTORNEYS,

United States Patent O 2,778,175 METHGD F SEALEJG CONTAINERS William H. Bryce, Memphis, Tenn., assignor to Dixie Wax Paper Company, Dallas, rllex.

Application November 1, 1950, Serial No. 193,390 1 Claim. (Cl. 53-39) The present invention relates to the method of effecting a rigid closure for flexible containers utilizing materials having thermoplastic adhesive properties and more particularly to paper bags coated with wax or a rubberywax-like composition.

It has been customary in the art of packaging foods in waxed coated glassine paper bags to fold over the upper opened end of the bag and apply heat and pressure thereto whereupon the wax-like coating is melted and squeezed in between the folds to eifect a vapor barrier and thereafter the wax-like coating is allowed to congeal at room temperatures forming a hermetic seal. When the Wax-like or rubbery-wax compositions employed in coating the glassine paper are subjected to temperatures of approximately 360 F. to 400 F. necessary to cause the heat to penetrate the paper folds and melt the coatings thereon, gases are given off from the volatile matter inherently contained therein. Certain commodities, such as foodstuffs, are very sensitive to such gases and may easily be contaminated thereby during such closure seam forming and sealing operations. Therefore, it is a primary object of the invention to provide a method of rigidly sealing the closures of containers coated with wax or rubberywax-like compositions w 'ch consists in the steps of applying heat to the closure at low temperatures of between 90 F. to 212 F. necessary to soften the coatings thereon without producing gases or fumes which are obnoxious or conducive to destroying the normal flavors of the foods stored within the container and thereafter, while the coatings are still in a softened state, to apply pressure thereto under reduced temperatures above 35 F. and below the softening point of the coatings whereby the latter will immediately congeal and produce a more effective vapor barrier through the closure of the container than the previous hermetic type seals employing excessive heat and pressure.

Another object of the invention is to provide a method of sealing the opened ends of a paper bag coatedwith wax or rubbery-wax-like compositions which comprises the steps of effecting a fold or double fold at the open end of a bag, applying heat directly to the opposed faces of each fold, without causing the heat to be driven through the folds, to soften the coatings thereupon and thereafter applying pressure to the folds under reduced temperatures whereat the coatings will be squeezed between the folds and caused to rapidly congeal.

And still another object of the invention is to provide a method of sealing the open ends of paper bags coated with wax or a rubbery-wax-like composition which consists yin feeding a label having a thermo-plastic coating thereon to a bag, folding the open end of the bag with a portion of a label therebetween, applying heat to the folds of the bag and label to soften the coatings thereon and thereafter applying pressure to the folds under reduced temperatures whereat the coatings will be caused to rapidly congeal for adhering the label to the bags.

A still further object of the invention'is to provide a Pce method of sealing the open ends 'of wax coated paper bags which consists 'in vthe steps `of folding over the open ends of the bags, applying heat to soften the wax coatings upon the folds of the bag at temperatures which will minimize and substantially eliminate the volatilization and obnoxious gaseous vapors being injected into the bag as would contaminate the foodstuffs therein, effecting a block-off ridge within the folds of the bag as an additional vapor barrier and thereafter subjecting the folds of the bag and ridge therein `to pressure at reduced temperatures as to cause the wax coatings to rapidly congeal.

And yet another object of the invention is to yprovide a progressive and continuous method of filling paper bags with foods, closing and sealing the open .ends of the bags after they are filled with foods which will be economical and greatly reduce the time 'now required for the packaging of foods.

Other objects of the invention'will be in part obvious and in part pointed out .hereinafter as the description of the method continues.

In the accompanying drawings:

Fig. l illustrates schematically in plan view a portable self contained machine having the stations indicated by the letters A, `B, C, D, E, and F each in a circle whereat the several steps of the method embodying the invention may be carried out;

Fig. 2 isa detail sideelevation partly in section of station A showing a paper bag in elevation as supported within the endless conveyor;

Fig. 3 `is a cross sectional view of the same;

Fig. 4 'is a similar View when the same bag as shown n Fig. 3 is expanded and at the station B for filling with food stuffs such as potato chips;

Fig. 5 is a similar view'when the same bag is moved to station C;

Fig. '6 is a fragmentary side elevation partially in section of stations D and E;

Fig. `7 is a detail cross section of station D villustrating the 4bag iu dotted lines after being conveyed from station C and having a label supplied thereto prior to the open end of the bag being folded and heated;

Fig. 8 is a similar view after the bag has received its rst fold;

Fig. `9 is a similar view after the bag has been raised and in a position for receiving its second fold;

Fig. l0 is asimilar view when the bag has been lowered and `heat applied to the bottom seam of the bag;

Fig. ll is a similar view when the same bag has been conveyed to station E;

Fig. 12 is a similar view when the same bag is conveyed to station F where it may by gravity be allowed o fall from the conveyorand "be permitted to drop upon another conveyor where it is moved to a suitable storage place or shipping box;

Fig. 13 is a side elevation of the same bag after it has been completely sealed;

Fig. 14 is an enlarged fragmentary view illustrating the upper open end of the bag when moved into a position prior `to applying heat thereto from the rollers and movable tucker iron;

Fig. l5 is a similar view when the tucker iron has been moved to force a portion of the lbag between the rollers;

Fig. 16 is a similar view showing the open end of the bag as it is drawn in between the rollers to give the bag Fig. 17 is a similar view showing the position of the folded upper end of the bag after it has been ejected from the rollers and allowed to drop therefrom;

Fig. 18 is a similar View showing the folded bag after it has` been elevated to receive its second fold;

Fig. 19 is a view similar to Fig. 15 when the folded portion of the bag is again moved by the tucker iron towards the rollers;

Fig. is a view similar to Fig. 16 when the rollers give to the bag its second fold;

Fig. 21 is a similar view showing the position of the double folded bag after it has been allowed to drop from the rollers and rest upon its supporting track;

Fig. 22 shows the position of the double folded bag top after being moved by the conveyor to station E between the molding and cooling irons;

Fig. 23 is a similar showing of the bag as it is being crimped between the molding and cooling irons; and

Fig. 24 is a similar view of the bag as it is released from the molding and cooling irons.

The bags 1 as herein employed and used for receiving a predetermined quantity of foodstuffs such as potato chips are formed from a strip of glassne paper coated with wax or a rubbery-waX-like composition to render the paper more transparent, with moisture and moisture vapor proofing qualities and heat sealing qualities. This so-coated strip of paper is then fed in the usual manner to a bag machine whereat the strip of paper is formed iiito a tube and with heat and pressure the back and bottom seams are formed leaving the upper end of the bag opened. These bags are usually of a standard length with varying widths of 4, 6 and 9 inches respectively. As the bags leave the bag machine, they are folded flat, that is, the sides are creased so that the opposite walls normally rest upon one another, as best illustrated in Fig. 3. These bags can be expanded as is illustrated in Fig. 4 of the drawings and are only about half lled with potato chips in order to leave a relatively long neck portion 2 which, when straightened out, will readily return to its original folded position, as best shown in Fig. 5.

A guided chain or other llexible conveyor 3 is intermittently moved in the direction of the arrow as shown in Fig. 1 about a supporting frame and also carried by the supporting frame below the conveyor 3 is a U-shaped track 4. This track 4 is so positioned upon the frame as to support bags of standard lengths whereby their neck portions 2 will be retained at the proper position for their closing and sealing operations, but in the event bags of other lengths are employed, this track may be adjusted vertically in order that the upper ends of all the bags will not extend beyond the height of the standard bag as shown in Fig. 2. Carried by the conveyor 3 are L-shaped fingers 5. These ngers are arranged in six groups and each group consists of two permanently secured end fingers 6, spaced about eighteen inches apart, and intermediate adjustable fingers 7. When a group of tingers are employed for holding 3 standard bags each having a width of six inches, they are arranged as best shown in Fig. l of the drawings. However, when employing bags each having a four inch width, the intermediate lingers 7 must be adjusted so that four bags may be placed between the end fingers 6 and when employing two bags each of a 9 inch width only two intermediate lingers 7 are necessary.

As a group of ngers are moved by the conveyor to station A, three bags of six inch Width are dropped between the fingers so that their lower ends will rest upon the bottom horizontal plate 8 of the track 4 as best shown in Figs. 2 and 3 of the drawings. 'I'he bags are stiff enough to remain vertically supported upon the track 4 and slide therealong, but the ngers 5 together with the conveyor chain will prevent the upper ends of the bags from falling sidewise from the track 4. This track has opposed side walls 9 for preventing the bags from sliding oli of the bottom plate 8 and guide the bags around the corners of the supporting frame. That portion of the track 4 in front of station D has its side walls 10 of a greater height than the side walls 9 and that portion of the track in front of station F has its outer side wal-l 9 removed and the bottom plate 11 inclined at an angle of about 45 as will permit the bags to slide from the track upon a conveyor 12.

After three bags have been deposited upon the conveyor at the station A, they are expanded preferably by a blast of air directed therein by a nozzle (not shown). The conveyor is thereafter moved in the direction of the arrow as shown in Fig. 1 until that group of bags at station A are moved to station B and then the conveyor comes to a full stop. Three additional bags are then deposited and expanded at station A and at the same time that group of bags at station B are each lilled with a predetermined quantity of potato chips.

The conveyor is again set in motion whereupon that group ot bags at station B are moved to station C and the conveyor again cornes to a full stop. At this station C salt and other avorings or avor stimulating materials are injected through the open ends of each bag whereupon the potato ch'ps will absorb the greater part of the avor from the tiavoring materials employed. An operator will thereafter straighten out the open ends of the bags whereupon the bags will each assume the position as best shown in Fig. 5. The conveyor is again set in motion whereupon that group of filled bags at station C will be moved to station D and again the conveyor comes to a full stop.

The bottom plate 8 of the track 4 has a plurality of transverse slots extending therethrough through which project the inverted U-shaped fingers 13 carried by a bar 14 and the latter being guided by the stationary supports 15 and vertically movable therebetween by means of the carri 16. Upon the rotation of the cam 16 the iingers 13 are first moved to the position as shown in Fig. '7 whereupon the bags 1 are elevated whereat their neck portions 2 are positioned between the heated rolls 17 and tucker iron 18.

At times it is desirable to place a label 19 upon each bag. These labels will have printing upon one or the outer face thereof and their opposite faces are coated with a thermo plastic of a rubbery-waX-like composition. As the labels are fed from the roll 20 they are individually severed by the cutter 21 and then allowed to drop to the position as shown in Fig. 7 upon the outer face of the bag with one end extending along the neck portion 2 thereof. The tucker iron 1S is then moved in the direction of the arrow as shown in Fig. 7 to force the neck portion 2 of the bag and label upon the rollers 17. The rollers, when rotated in one direction, will at first draw in the neck portion of the bag and label therebetween to fold over the upper end of the bag. As the rollers 17 are rotated in an opposite direction, the neck portion of the bag will be ejected therefrom and the bag allowed to drop by gravity upon the fingers 13.

Upon the further rotation of the cam 16 the fingers 13 will descend to the position as shown in Fig. 8 whereupon the lower edge of each bag will be retained above the plate 8 of the track 4. The upper open end of the bags will be then closed by a single flap with one edge of the label 19 retained therebetween. To form an additional barrier to the vapors or moisture avorings within the bags, these upper ends may be given an additional fold. To obtain this second fold, the cam 16 upon its further rotation elevates the fingers 13 carrying the bags therewith until the neck portion of the bags are again between the heated pull-in rollers 17 and tucker iron 18 as shown in Fig. 9 of the drawings. After this second fold has been made, the bags are again ejected from the rollers and released whereupon they will drop to the position as in Fig. l0. The cam 16 is further rotated until the upper ends of the ngers 13 drop within the slots of the track 4 whereupon heat from heater 22 softens the wax coatings along the bottom seams of the bags and the upper folded ends of the bags are out of the path of the pull-in rollers 17 and tucker iron 18.

The conveyor is again set in motion whereupon that group of bags at station D with their upper ends folded and the wax coatings at their upper and lower ends softened are moved to station E and is again brought to a full Stop. As this group of bags reaches station E,

their folded neck portions 2 are positioned between the cooling and molding irons 23 and v24. The iron 23 vis stationary and the iron 24 is movable so that when it is forced towards the iron 23, the neck portion of the bags are molded and cooled until the softened wax thereupon congeals making a complete seal. Thereafter the iron 24 is moved outwardly or from the iron 23 so as to release the bags molded and cooled therebetween. The lower seams of the bags that have been previously heated by the heater 22 are then allowed to cool to room temperatures whereupon the softened wax is allowed to congeal for giving to the bottom of each bag a double seal.

The conveyor is again set in motion whereupon that group of lled and sealed bags at station E are moved to station F and the conveyor again comes to a full stop. As the bottom 1l of the track 4 is inclined the bags will slide by gravity down upon the conveyor 12 or into suitable packing boxes arranged thereupon.

As the L-shaped end conveying fingers 6 of cach group are spaced within a distance along the conveyor 3 of about 18 inches and spaced at about six inches between each group the conveyor 3 travels only about twenty-four inches with cach intermittent movement in the direction of the arrow as shown in Fig. l0. lt takes about one second for the conveyor to travel 24 inches and then it comes to a full stop for about two seconds in which latter time the operations upon the bags at each station must be completed.

Iournalled within the bearings 25 supported by the table top of supporting frame is a driven shaft 26. A belt driven pulley 27 is keyed to the shaft 26 and the belts thereof extend over a pulley of the gear box 28 mounted upon a lower shelf of the support-ing frame. Also operatively connected to the gears of the box 28 is a drive wheel 29 in mesh with the conveyor chain 3. An electric motor Sil drives the gears of the box 2S and the latter are so timed as to give the required intermittent motion to the conveyor 3 and at each stop period of the conveyor 3, the shaft 26 given one complete revolution. Operatively connected to the shaft 26 through the reducing gearing 3l is a reciprocating drive rod 32 and the latter is connected to the segmental gears 33 keyed to the sl afts of the heater rollers 17. whereupon with each revolution of the shaft 26 the rollers will be oscillated twice in opposite directions. The rollers 17 are spring pressed together as at 34 whereby the gears 33 will at ali times he retained in mesh, but ailowing sufiicient separating movement between the rollers 17 as to permit the folded ends 2 of the bugs to pass therebetween.

Operativcly connected to the cam 35 keyed to the shaft 26 is a frame 36 having connected to its outer end the tucker iron f3 whereupon with each revolution of the shaft 26 the tucker iron 1t', will be twice moved to and from the rollers 17.

Another cam 37 is keyed to the shaft k26 and has operatively connected thereto a frame 38 supporting the cooling and molding iron 24 whereupon with each revolution of shaft 26 the iron 24 will be moved to and from the iron 23. A sprocket wheel 39 is also keyed to the shaft 26 which through a sprocket chain connection dit rotates the cam 16 for imparting the elevating motions to the fingers 13.

The electrical wiring system includes the main conduits 41 having switch controlled leads 42 to the motor 3@ and leads extending to a distribution panel 43. Lead conductors 434 extend from this panel 43 for supplying electrical energy to the two heaters 45 arranged within the tucker iron i3. The conductors i6 lead to the heater 47 within the upper roller 17 and the conductors 48 lead to the eater 9 arranged within the lower roller 17.

Another set of conductors 56 lead to the heater 22 employed for softening the wax upon the lower sealed seams of the bags. A rheostat l is also included in the electrical system whereby manual temperature control may be .had of 4the heaters 22, 45, 47 .and 49 yso that vthe softening point of the wax coatings upon the bags may be at all .times maintained. The softening temperatures ofthe wax coatings being about F. and therefore these heaters should never exceed 212 F.

Extending from the opposite ends of the cooling and molding irons 23 and 24 are flexible conduits 52 whereby cold water or brine may be circulated therethrough or they may have connection with the respective inlet and outlet conduits of the thermostatically controlled refrigerating unit. The pipe 53 conducts the refrigerant to the conduits 52 of the irons 23 and 24 whereas the pipe 54 conducts the spent gases to the compressor 55 and the latter can be driven by the drive chain 56 connected to the motor 30. Also included in the refrigerating system is the conventional receiver 57, condenser 58 and dual pressure control 59. The expansion chambers within the irons 23 and 24 are provided with vbattle plates 60 so as to retard the refrigerant as it passes therethrough. The cooling temperatures of these irons 23 and 24 should preferably be maintained `to about 35 F. whereby the softened wax coatings upon the bags will be caused to jell rapidly.

The neck portions of the bags may be folded and heated with or without the labels as is suggested in Fig. 7 of the drawings. In Figs. 14 to 17 inclusive I have schematically illustrated the four steps of the method of heating and applying a single fold to the open ends of the bags. The neck portion 2 of a bag is elevated in the direction of the arrow as shown in Fig. 14 until it assumes a position as shown between the pull-in rollers 17 and the tucker iron 18. With the rotation of the shaft 26, the cam 35 draws the tucker iron 18 towards the rollers 17 until the neck 2 of the bag assumes the position as shown in Fig. 15. It will be herein noted that as each roller has a heater 47 or 49 thereinY the heat from these rollers will be applied directly to one face of the bag. The tucking surface of the iron 18 has two curved faces corresponding to that of the rollers 17 so as to press the neck 2 of the bag against the rollers. The two heaters 45 within the iron 18 are arranged adjacent the curved faces thereof so that heat will be applied to the opposite or outer face of the bag. By so applying heat to the bag its opposed wax coated surface will be completely and thoroughly heated, but by positive control of the heat temperatures of about 90 F., or that of the softening point of the wax coatings must be maintained through the rheostat 51. Through the connection 32 to the shaft 26 the rollers 17 are at rst caused to rotate in the direction of the arrow as shown in Fig. 16 whereupon the upper end of the bag will be given a fold as it is drawn in between the rollers and at the same time the iron 18 is moved by the cam 35 from the rollers 17 in the direction of the arrow. After the bags open end has been folded the rollers 17 are oscillated by the rod 32 through its connection with the drive shaft 26 in the direction of the arrows as shown in Fig. 17 whereby the folded end of the bag is ejected from the rollers 17 and allowed to drop by gravity under its own weight upon the supporting ngers 13 as illustrated in Fig. 8.

At times it is desirable to give to the bag a double fold and to accomplish this, the four steps in forming this double fold is illustrated in Figs. 18 to 21 of the drawings. The bag with the single fold is again raised to the position as shown in Fig. 18 and then the tucker iron is moved in the direction of the arrow as shown in Fig. 19 whereat the opposed wax coated surfaces of the bag again have heat directly applied thereto. With the rotation of the rollers 17 in the direction of the arrows shown in Fig. 20 the bag is drawn in between the two rollers to form the second fold and the tucker iron 18 is moved from the rollers. As the rollers 1'7 are again moved in the direction of the arrow as shown in Fig. 21 the bag with the double flap is ejected therefrom and allowed to drop upon the track 4 where through the heater 22 arrears the wax coating upon the lower or bottom seam of the bag becomes softened.

As it takes about one second of time'to move the group of bags at station D to station E, that portion of the wax coatingwhich has been heated will remainsoftened until subjected to the lcooling and molding operations. In Figs.` 22 to 24 inclusive, I have illustrated schematically three steps of the method which are required to accomplish the cool'mg and molding operations. The double folded end of the bag is moved between the irons 23 and 24 as illustrated in Fig. 22. To form an additional vapor barrier the bags may be crimped or corrugated as at 61 across the entire folded ends of each bag and to accomplishithe latter the cooling iron 23 has a recess 62 formed in lone face thereof and the movable iron 24 has an integral protuberance or tucker blade 63 capable of moving into and out of the recess 62. As the iron 24 moves in the direction of the arrow as shown in Fig. 23 to cool and inold the folded end of the bag neck 2, the blade 63 forces a portion thereof within the recess 62 to crimp and form the ridge 61.l The opposed fiat surfaces of the irons 23 and 24 must have a high polish and be free from any high or low places so as to squeeze out all air between the folds of the bag at the time the softened coating thereupon is congealed. As the iron 24 moves outwardly or in the direction of the arrow as shown in Fig. 24 the bag will be released and allowed to drop down upon the track 4. As the conveyor moves, the bags will pass between the irons 23 and 24 until they are moved to station F. At times it is desirable to apply additional corrugations or code markings 64 upon the sealed end of the bags whichcan be done with additional recesses in the iron 23 and projections from the iron 24 whereby these markings will represent in code the date when the bags were so filled and sealed. Brass or copper wire wrapped around one or both of the irons 23 and 24 may be alternately employed for leaving a code imprint upon the folds of a bag or a print applying ribbon may be inserted between the irons as preference or conditions mayvdictate.

The cam 31 which transmits elevating motions to the ngers 13 is capable of at first raising the bags to a height of approximately 1% of an inch so that as the bags are pulled-in between the rollers a iirst fold of 3%: of an inch in length will be made. The so folded bags are allowed to drop only li of an inch so that on the second cycle of the pull-in rolls a second fold of about 1/2 inch'in length will be made. By substituting other-cams than that indicated by the numeral 31, the length of travel of theA fingers 13 may be so controlled as to permit folds of varying length to be'made. The spring pressure upon the rollers 17 Amay allow any number of folds to pass therebetween and accordingly, no adjustment is necessary when either single or duplex bags are employed.

By applying heat-at low temperatures directly to the wax coated faces of the bag instead of heat at excessive temperatures necessary to penetrate the folds of the bag,

the coatings are softened without producing fumes or vapors that would be obnoxious or conducive to the avor of the potato chips within the bag. As the softened coatings upon the bags are subjected to pressure from the cooling irons 23 and 24, they are forced between the folds of the bag and crevices therein excluding all trapped air and as the softened coatings congeal, a hermetic seal is produced which latter has been found to be far superior to hermetic seals wherein high temperatures are required to melt the coatings and pressure without reduced temperatures are employed.

ln order to improve the sealing qualities of wax coatings upon the bags glue or other adhesives may be applied |to the tuck-in blade of the tucker arm 18 so that as the tops of the bags are pressed towards the rollers 17 the glue will be transferred to the so-softened Wax coating thereon and when allowed to dry will assist the wax coatings in retaining -the folds of the bag together. By heating the wax coatings at low temperatures as between 90 and 212 F. they will be at the right softening point and remain so until the cooling and pressure steps are applied. In other words, the temperature and timing have a great deal to do with the proper sealing and the heating elements must operate at just as low as possible heat temperatures as will maintain this softening point until the bags are moved to the cooling unit without giving off vapors conducive to destroying the normal avors of the foods contained within the bags.

lclaim:

The method of sealing wax coated paper bags which comprises the steps of applying heat to each face of the open end portion of the bag, simultaneously bending said end portion laterally of the bag sealing olf the interior of the bag from the portion thereof being heated, discontinuing the application of heat to the inner face only of said bent end portion, pressing said bent end portion together forming a fold thereof, applying heat to the outer faces of the remaining end portion of the bag including said fold, simultaneously forming a bend laterally of said bag below said fold, discontinuing the application of heat to the linner face of said second bent portion of the bag, pressing said bent portion together forming a second fold, thereafter quick cooling the sealed end portion of said bag while under pressure and forming corrugations in said folds during the pressing and cooling thereof.

References Cited in the tile of this patent UNITED STATES PATENTS 1,914,369 Hohl June 20, 1933 1,956,160 Shoemaker Apr. 24, 1934 2,011,198 Morey Aug. 13, 1935 2,018,806 Richard Oct. 29, 1935 2,114,624 Bergstein Apr. 19, 1938 2,156,441 Watkins et al. May 2, 1939 2,218,585 Merkle Oct. 22, 1940 2,253,036 Kimple et al Aug. 19, 1941

Images