US3462916A

US3462916A - Apparatus for heat sealing cartons

Info

Publication number: US3462916A
Application number: US565972A
Authority: US
Inventors: Arthur H T Chin
Original assignee: Fibreboard Corp
Current assignee: Fibreboard Corp
Priority date: 1966-07-18
Filing date: 1966-07-18
Publication date: 1969-08-26
Anticipated expiration: 1986-08-26
Also published as: SE354625B; GB1144757A; DE1611622B1; BE699593A; NL6707264A

Description

Aug. 6, 1969 A. H. T. CHIN 3,462,916

5 Sheets-Sheet 1 YNVENTO ARTHUR H. T CHIN Bu; a OQZ/Qw 1 ATTORNEYS Aug. 26, 1969 A. H. T. CHIN 3,462,916

APPARATUS FOR HEAT SEALING CARTONS Filed July 18, 1966 5 Sheets-Sheet 5 IINVENTOR, ARTHUR H. T. CHIN BY w z wwz ATTORNEYS United States Patent 3,462,916 APPARATUS FOR HEAT SEALING CARTONS Arthur H. T. Chin, Castro Valley, Calif., assignor to Fibreboard Corporation, San Francisco, Calif., a corporation of Delaware Filed July 18, 1966, Ser. No. 565,972 Int. Cl. B65b 7/20, 51 /20,' F24h 3/04 US. Cl. 53375 24 Claims ABSTRACT OF THE DISLQSURE This invention relates to an apparatus and method for heat sealing cartons and more particularly relates to an apparatus and method for applying heated air to selected portions of adhesively treated carton flaps and sealing them together.

The packaging of butter, ice cream and like perishables generally requires a mechanical lock, conventional glues or a carton overwrap to assure carton integrity and to prevent spoilage of the product retained therein. The application of heat to the cartons flaps to effect sealed end closures gives rise to a number of problems which are not totally solved by conventional apparatus and methods. For example, such apparatus and methods are generally arranged to conduct or otherwise convey a substantial amount of heat whereby the packaged product becomes contaminated or otherwise damaged. Also, certain adhesive materials may be damaged or lost due to such high heat concentrations. In addition, the carton oftentimes becomes scorched or otherwise defaced due to a high heat concentration at portions thereof. Also, a tight end closure is not always effected to assure a high degree of structural integrity to the carton for shipping and like purposes.

The instant invention provides an apparatus and method adapted to overcome such difliculties and particularly adapted for the packaging of perishables, such as ice cream and butter by using hot air for carton sealing purposes. Attention is drawn to United States Patent No. 3,248,843 and United States patent application Ser. No. 457,893, both assigned to the assignee of this application, which disclose apparatus and methods particularly adapted to employ air maintained at substantially high temperatures and volumes to heat seal adhesively treated carton flaps.

This invention, on the other hand, is capable of utilizing heated air at a substantially low volume and temperature thus requiring less power input to the heating means employed to heat the air. The nozzle bar employed to subject the carton flaps to hot air is further adapted to conduct heat directly to the carton flaps. The heat may be thus concentrated at selected areas of the carton flaps to increase sealing rates, also eliminate scorching or other types of defacing of paperboard surfaces and prevent damage to the adhesive utilized. Thus, carton end closures may be sealed rapidly, heat losses are minimized and little, if any, heat is transferred to the product contained in the carton.

An object of this invention is to provide an apparatus and method whereby a low volume of heated air may be utilized to effect an eificient carton seal expeditiously and economically without transferring appreciable amounts of heat to the cartons contents or causing carton defacing.

Another object of this invention is to provide an elongated and narrow nozzle bar means in a heat sealing apparatus arranged to efficiently and rapidly seal adhesively treated carton portions together.

A further object of this invention is to provide an apparatus for heat sealing carton flaps comprising a nozzle bar and flap control bar means adapted to be arranged for sealing various carton flap arrangements.

Further objects of this invention will become apparent from the following description and accompanying drawings, wherein:

FIG. 1 is a view with parts broken away illustrating an apparatus embodying novel aspects of this invention as it would appear during a carton sealing operation;

FIG. 2 is an end elevational view of a heat sealing means employed in the apparatus illustrated in FIG. 1;

FIG. 3 is a side elevational view of the heat sealing means illustrated in FIG. 2 with portions thereof broken away for clarification purposes;

FIG. 4 is a cross sectional view taken in the direction of arrows 4-4 in FIG. 2;

FIG. 5 is a view taken in the direction of arrows 5-5 in FIG. 1 with parts broken away for clarification purposes;

FIG. 6 is a view taken in the direction of arrows 6-6 in FIG. 1 with parts broken away for clarification purposes;

FIG. 7 is a view illustrating an attachment for a flap hold-down bar employed in the apparatus of FIG. 1;

FIG. 8 is another embodiment of a heat sealing means of this invention; and

FIG. 9 illustrates typical carton end flaps which may be sealed pursuant to the teachings of this invention.

Referring to FIG. 1, the apparatus embodying novel aspects of this invention comprises a conveyor means 20 having spaced lugs 21 attached to continuous chains thereof. The conveyor means is arranged for moving a conventional carton C along a linear path P in the direction of the illustrated arrow. In actual practice, conveyor speeds of from 30 to f.p.m. have been successfully employed. Referring briefly to FIG. 9, the carton may comprise adhesively treated major flaps F and F and minor flaps F and F The term adhesive as used herein should be understood to mean any pie-applied fuseable coating adapted to be activated by heat for sealing paperboard or like panels together. For example, such adhesive may constitute a heat scalable wax, polyethylene, polyvinyl chloride or the like. The carton may constitute paperboard or other suitable packaging material either partially or totally coated with such an adhesive.

The flaps are suitably arranged to be folded into position by conventional flap folding means (not shown), preferably mounted in a stationary manner in the apparatus. A stationary hold-down bar means 22 is arranged over the carton to urge it downwardly, as more clearly illustrated in FIG. 6. The lower, slanted surface of the hold-down bar is preferably arranged to make only a line contact with the carton to prevent undue scuffing thereof.

A flap control bar means 23 is arranged to position and hold flap F substantially in a fixed plane during such carton movement. As more clearly illustrated in FIG. 6, a tapered surface 23a of the flap control bar is preferably arranged within an angle A of from 5 to 20 relative to a vertically disposed plane to "correctly position flap F It should be further understood that surface 23a can be arranged in a tapered manner so as to gradually close flap F when it moves through the heat sealing means. The hereinafter explained nozzle bar means could be likewise modified in a tapered manner to facilitate a gradual closing of the carton flaps.

The flap control bar is associated with adjusting means (FIG. 7) comprising spaced

extensions

23b and 23b, secured thereto to selectively vary angle A. The adjusting means, preferably located at each end of the flap control bar, are identical and thus identical numerals accompany like elements. The numerals depicting elements included in the assembled adjusting means located leftwardly in FIG. 7 are accompanied by a prime symbol however.

Extension 23b has an aperture suitably formed therein and arranged to receive pin 230 which mounts trunnion 23d. The trunnion preferably comprises a threaded post 23a arranged to extend through an aperture formed in a stationary bar 23 and secured thereto by a nut 23 Adjustment screws 23g and 2311 are suitably threaded in bar 24 to permit rotation of flap control bar 23 about the axis of pin 23c and thus adjustment of angle A. For example, if it is desired to lessen angle A (FIG. 6) screws 23/1 and 23h would be extended a predetermined amount and

screws

23g and 23g retracted a like amount. It should be noted that the ends of such screws are preferably rounded and merely abut flat outer surface portions of

extensions

23b and 23b.

Referring again to FIG. 1, L-

shaped braces

25 and 26 are secured to the stationary bed of the machine. Bar 24, supporting adjustable flap control bar 23, is preferably secured to brace 25 by a bolt 27. The braces are further arranged to support carton hold-down bar 22 by means of suitably arranged attachment means 28 and 29. A heat sealing means 30 is attached to the machine to heat seal flaps F and F together as will be hereinafter more fully explained. The heat sealing means comprises a housing 31 attached to the bed of the machine by an inverted L- shaped plate member 32 (FIG. The housing preferably constitutes a metallic constituent, such as aluminum or bronze, constructed to conduct heat particularly through the nozzle portion thereof.

One or more bolt and spacer arrangements 32a may be arranged to threadably secure a side wall of housing 31 to member 32 in the manner shown. In turn, an adjusting means, comprising a bolt 32b, preferably arranged at each end of member 32, secures a horizontally disposed portion of member 32 to a plate 33, detachably secured to the bed of the machine. Thus, rotation of

bolts

32b and 32b will function to move housing 31 in a vertically disposed plane. The adjusting means further comprises

screws

32c and 32d, threadably secured to such portion and arranged to selectively vary an angle B between such verti cally disposed plane and a vertically disposed axis of housing 31 (FIG. 5) for purposes hereinafter explained.

A spherically shaped washer 322 is preferably arranged between the head of bolt 32b and member 32 to facilitate such adjustment. For example, if it is desired to lessen angle B, screws 32c and 32c (FIG. 1) would be extended and screws 32d and 32d would be retracted from member 32. As above mentioned, it is preferred to employ an adjusting means at each end of member 32 for stabilization purposes. However, in certain machine applications a single adjusting means could be employed. Corresponding elements of the second adjustment means (illustrated in assembled form) are depicted by like numerals accompanied by a prime symbol Referring now more particularly to the construction and arrangement of housing 31 of the heat sealing means illustrated in FIGS. 2-5, a closure plate 31a is detachably secured to the bottom thereof to enclose a preheating chamber 31b. The air is communicated to chamber 31b via conduit 31c and is thereafter permitted to flow through an elongated opening 31d. The air is preheated due to contact with internal heated surface portions of metallic housing 31.

A conventional pump 34, rated at 2-15 c.f.m. of air and set at 2-10 p.s.i., for example, may be utilized to supply the incoming air via conduit 310 (FIG. 5). Elongated opening 31d communicates with a plurality of slots 31e forming fins therebetween, radially arranged about a removable and cylindrically shaped heating means or cartridge heater 31 Heater 31 has been removed from housing 31 in FIGS. 2-4 for clarification purposes. A Chromolox C 505 heater rated at 1100 watts and 240 V. AC. and also a heater rated at 525 watts and V. AC. have been used successfully.

The slots are further arranged to communicate with a nozzle bar means comprising a plurality of radially eX- tending and drilled passages 31g arranged intermediate tapered first and second side surface portions thereof and may be arranged within an angle C selected from a range of from 0 to 20 (preferably 5 to 15). As above explained, the thickness of the nozzle bar means may be varied along the length thereof to effect a gradual losing of the carton flaps if so desired for certain carton sealing applications. Such passages are further arranged to communicate the air heated by heater 31 to drilled orifices 31h formed in such surface portions and arranged in substantial parallel relationship to a top surface portion of the nozzle bar means whereat the side surface portions terminate. The orifices are preferably arranged to impart the heated air directly to opposed surface portions of adhesively treated flaps F and F (FIG. 6).

It should be understood that a greater or lesser number of such orifices may be employed and arranged in selected patterns on the nozzle bar means different from that shown. For example, such orifices could be formed on only one of the first and second surface portions of the nozzle bar means. In addition, it has been found that carton C, the nozzle bar means and flap control bar 23 may be arranged to permit the heated air discharged from orifices 3111 to cause the adhesive preapplied to flap F and/or F to be formed into selected patterns. For example, the nozzle bar means in FIG. 6 could be rotated counter-clockwise and flap control bar 23 moved leftwardly to effect a line contact between the parallel edges of the top surface portion of the nozzle bar means and flaps F and F Such an arrangement would prevent the heated air discharged from orifices 3111 from moving upwardly, above the nozzle bar means. Such air would be forced downwardly to cause the pre-applied adhesive into a bead-like configuration adjacent the free edge of flap F and the juxtaposed portion of flap F As clearly illustrated in FIGS. 2 and 5, a conventional heat sensing means 311', such as a Fenwal 17202-0 thermoswitch or thermostat, is preferably attached to housing 31 to have the temperature of the heated air conducted thereto via narrowed portions of the housing to constantly control such temperature preferably within a range of from to 600 F. A conventional control means 35, schematically illustrated in FIG. 5, may be utilized for automatically controlling the heat output of heating means 31 The tapered first and second portions of the nozzle bar means are preferably arranged to abut the portions of the carton flaps to be sealed (illustrated in spaced relationship in FIG. 6') during passage of the carton through the heat sealing means.

Such an arrangement permits the heating efiects caused by the air discharged via orifices 3111 to be supplemented by the heat conducted to the sealed flap portions through the metallic nozzle bar means. The fins arranged to form slots 31e are constructed and arranged to heat and maintain the nozzle bar means at a temperature which is substantially the same as the temperature of the air emitted from nozzles 3171. The flaps may be held in close proximity to each other to effect a rapid seal due to this atrangement which permits heat, at a substantially constant temperature, to be concentrated at the carton portions to be sealed. Also, the low pressure air further functions as a lubricant to prevent sloughing-olf of the pre-applied adhesive.

Once the adhesively treated carton flaps are subjected to heat via the nozzle bar means, conveyor 20 continues to move the carton past compression means 36 (FIG. 1), preferably in the form of an endless belt, to rapidly effect a tight seal, i.e., no elaborate sealing or cooling means need be employed to seal the carton due to the low sealing temperature employed. Two such belts are preferably employed to slightly compress the carton therebetween to effect such sealing. Such compression means could also comprise suitably arranged compression bars or the like. It should be noted that constructions and arrangements substantially identical to those described above are also employed in parallel relationship on the opposite side of the machine to thus simultaneously effect an end closure at each end of the carton. Such compact arrangements differ from conventional ones wherein rather lengthy sealing means for effecting carton end closures are positioned in series.

FIG. 8 illustrates a modified form of the heat sealing means. Like numerals, accompanied by a prime symbol depict corresponding structures included in the first described heat sealing means embodiment. A closure plate 31a is arranged to enclose a preheating chamber 31b. Elongated opening or slot 31d communicates with radially extending slots 312' and passages 31g which in turn communcate air to orifices 31h. Heater 31f is arranged to have a portion thereof directly heat the air passing through passages 31d.

The following method is preferably employed to secure opposed carton portions together (in this instance flap F to F as illustrated in FIG. 1. Conveyor 20 is arranged for moving carton C along linear path P during which movement control bar 23 is arranged for positioning and holding flap F in substantially the same plane during movement through heat sealing means 30. As more clearly illustrated in FIG. 6, the apparatus is further arranged for holding flaps F and F in close proximity to each other on each side of the nozzle bar means. Heated air at a low pressure, preferably from 1 to p.s.i., is discharged from orifices 31h and imparted directly onto selected portions of the adhesively coated flaps F and F As above mentioned, although the flaps are illustrated as being slightly spaced from the nozzle bar means in FIG. 6, it should be understood that in actual practice it is preferred to maintain the flaps in substantial contact with the nozzle bar means. Thus, the nozzle bar means may be utilized to perform a two-fold heat transferring function, i.e., discharging heated air via orifices 31h and conducting heat therethrough to the flaps. Compression means 36 are arranged for compressing the flaps together to form carton end closures.

In actual practice, a temperature setting of from 400 to 480 F. for heater 31f was found to efliciently heat the air utilized for the sealing of a carton coated with polyethylene. During such application, conveyor means was set at 82 feet per minute to convey approximately 70 cartons per minute through the heat sealing means. Eflicient seals were obtained when the conveyor speeds were varied within a range of from 46 feet per minute to 117 feet per minute with the temperature setting being maintained within a range of from 440 to 480 F. The air supply utilized was rated at approximately 6 cubic feet of free air per minute and maintained at approximately 2 to 3 p.s.i.

I claim:

1. An apparatus for sealing opposed adhesively treated flaps of a carton together comprising conveyor means for moving said carton along a linear path, control bar means arranged in substantial parallel relationship to said linear path and having a surface formed thereon for positioning and holding one of said flaps during carton movement by said conveyor means and a heat sealing means comprising a housing having an elongated and narrow metallic nozzle bar means arranged thereon in substantial parallel relationship to said linear path, said nozzle bar means having first and second fiat surface portions terminating at an edge thereof, said first surface portion positioned in close juxtaposed relationship to said control bar means to have said one flap maintained in substantial contact with said first surface portion and the surface of said control bar means, said nozzle bar means further comprising a plurality of orifices formed in at least the first surface portion thereof and passage means formed therein for communicating heated air to said orifices and heating means operatively associated with said nozzle bar means for conducting heat through metallic portions thereof and for heating air communicated through said passage means whereby the adhesive on said one flap contacting the first flat surface portion of said nozzle bar means is simultaneously activated by heat conducted through said nozzle bar and by said heated air.

2. The invention of claim 1 wherein a plurality of said orifices are formed in each of said first and second surface portions, each one of the orifices formed in said first surface portion arranged to communicate directly with an orifice formed in said second surface portion.

3. The invention of claim 1 further comprising holddown bar means arranged over and in juxtaposed relationship to said nozzle bar means for urging said carton towards said nozzle bar means, said nozzle bar means further arranged to extend substantially vertically upwardly towards said hold-down bar means.

4. The invention of claim 1 wherein said first and second surface portions of said nozzle bar means are arranged to taper towards each other and wherein the included angle therebetween is from 5 to 20*".

5. The invention of claim 1 wherein a second of said heat sealing means is arranged on a side of said apparatus opposite to a side whereat the first-mentioned heat sealing means is arranged.

6. The invention of claim 1 further comprising compression means arranged adjacent to said nozzle bar means for receiving cartons therefrom and compressing said flaps into sealed relationship.

7. The invention of claim 1 wherein said housing comprises a chamber formed therein, and said heating means comprises a removable heating means inserted into said chamber and arranged to heat air in said chamber and to conduct heat to said nozzle bar means, said chamber further arranged to communicate with said passage means.

8. The invention of claim 7 further comprising temperature sensing means associated with said housing adjacent to said chamber and operatively associated with said heating means for controlling the heat output thereof.

9. The invention of claim 1 further comprising means adjustably mounting said housing in said apparatus.

10. In an apparatus comprising heat sealing means for heat sealing opposed, adhesively treated portions of carton flaps together, a housing having a chamber formed therein, a nozzle bar means having a plurality of apertures formed therein for discharging heated air therethrough, heating means arranged in said chamber, a plurality of fins constructed and arranged in said chamber to substantially surround and contact said heating means and a plurality of slots formed between said fins and arranged to communicate air to said apertures after said air has been heated by said heating means and means for applying pressure to said flaps to seal them together.

11. The invention of claim 10 wherein said housing, including said fins, is further constructed and arranged to conduct heat from said heating means to said nozzle bar means to heat and maintain the nozzle bar means at a temperature which is substantially the same as the temperature of the air discharged from said apertures.

12. In an apparatus comprising a heat sealing means adapted to heat seal opposed, adhesively treated portions of carton flaps together, the invention comprising an elongated and narrow metallic nozzle bar means having at least one surface formed thereon, a plurality of apertures formed in said surface and passage means formed in said nozzle bar means arranged to communicate heated air to said apertures, a flap control bar closely juxtaposed and parallel to the surface of said nozzle bar means to hold one of the carton flaps in substantial contact with said surface and heating means operatively assocated with said nozzle bar means for simultaneously conducting heat therethrough and for heating air in the passage means thereof whereby said one carton flap is subjected to a combination of heat conducted through said nozzle bar means and heated air communicated through said apertures.

13. The invention of claim 12 further comprising adjusting means for moving said flap control bar to selectively vary the inclination thereof relative to the surface of said nozzle bar means.

14. The invention of claim 13 wherein said flap control bar is pivotally mounted in said apparatus and said adjusting means comprises at least one screw means for selectively pivoting said flap control bar to vary the inclination thereof.

1-5. The invention of claim 12 further comprising holddown bar means arranged in juxtaposed relationship to said nozzle bar means for urging said carton towards said nozzle bar means.

16. The invention of claim 15 further comprising adjusting means arranged for moving said nozzle bar means in a vertically disposed plane.

17. The invention of claim 14 wherein said adjusting means is further arranged for moving said nozzle bar means to selectively vary the angle between said vertically disposed plane and a vertically disposed axis of said nozzle bar means.

18. The invention of claim 12 wherein said nozzle bar means comprises first and second fiat surfaces arranged to taper towards each other and wherein the included angle therebetween is sealed from a range of from 5" to 19. The invention of claim 18 wherein a plurality of said apertures are formed in each of said first and second flat surfaces.

20. The invention of claim 12 wherein said heat sealing means further comprises a housing and said heating means is removably mounted therein.

21. An apparatus for heat sealing opposed adhesively treated portions of carton flaps together comprising a housing having a chamber formed therein, a metallic nozzle bar means having at least one flat and substantially uninterrupted surface and a plurality of apertures formed therein communicating with said chamber for discharging heated air therethrough, heating means in said chamber and associated with said nozzle bar means to conduct heat through metallic portions thereof such that said adhesively treated portions of said carton are heated by a combination of said heated air and heat conducted through the metallic portions of said nozzle bar means and means for applying pressure to said flaps to seal them together.

22. Apparatus according to claim 21 wherein said apparatus further comprises a plurality of fins constructed and arranged in said chamber to substantially surround and contact said heating means, and a plurality of slots formed between said fins and arranged to communicate air to said apertures after said air has been heated by said heating means.

23. Apparatus according to claim 22 wherein said housing and said fins are further constructed and arranged to conduct heat from said heating means to said nozzle bar means to heat and maintain the nozzle bar means at a temperature which is substantially the same as the temperature of the air discharged from said apertures.

24. Apparatus according to claim 21 wherein said nozzle bar means is elongated and has first and second flat and substantially uninterrupted surfaces terminating at a top edge of said nozzle bar means, said plurality of apertures being formed in both said first and second surfaces, said apertures communicating with said chamber by passage means formed in said nozzle bar means.

References Cited UNITED STATES PATENTS 3,248,843 5/ 1966 Winters et al. 53-373 X 3,249,024 5/ 1966 Shiu 156-497 X 3,336,464 8/ 1967 Hittenberger et al. 156497 X 3,340,777 9/1967 Hittenberger et al. 53-375 X TRAVIS S. MCGEHEE, Primary Examiner U.S. Cl. X.R. 219 374