US2930175A - Carton sealing apparatus - Google Patents

Description

March 29, 1960 w. JONES CARTON SEALING APPARATUS 4 Sheets-Sheet 1 IN VEN TOR.

A TTOENEYS.

Filed April 3, 1956 8 MMMN uo MI. 2 Q. AN AN M m S a z. 8 AA 5 n n o Vb o 0 50 V9 8 3 nimm 2/, s2 H 5 5 5 2 6. a. M on N v o w a. i Am M Illv J w No on S M #9 3 map ma om m March 29, 1960 w JONES 2,930,175

CARTON SEALING APPARATUS 4 Sheets-Sheet 3 Filed April 3, 1956 BY Imam/101m min-am ATTDEAM'YQ March 29, 1960 w, JONES 7 2,930,175

' CARTON SEALING APPARATUS Filed April 3, 1956 4 Sheets-Sheet 4 8w INVENTOR. fi mlwfiw nrragmy s,

CARTON SEALING APPARATUS Wicklii're Jones, Cincinnati, Ohio, assignor to R. A. Jones and Company, Inc., Covington, Ky., a corporation of Kentucky Application April 3, 1956, Serial No. 575,741

2 Claims. (Cl. 53-388) This invention is directed to an apparatus and method for drying and sealing the adhesively coated flaps or cartons as they issue from a cartoning machine with the flaps freshly glued and folded to closed position. The apparatus is intended particularly for flaps having an adhesive coating which sets or dries rapidly when heated, such as vegetable or animal glue applied in liquid form to the flaps.

One of the primary objects of the invention has been to utilize continuously advancing heat exchange elements which engage the freshly glued flaps to hold them firmly in closed position while transferring heat to the flaps to dry the glue coating as the cartons advance through the apparatus to its discharge end.

In the disclosure which is selected to illustrate this principle, the opposite ends of the carton include inner and outer flaps, the liquid adhesive being applied by the cartoning machine to the outer flaps while they are in unfolded position. The machine then folds the glued outer flaps over upon the inner flaps with the adhesive coating of the outer flaps in facial contact with the previously folded inner flaps. The carton is then advanced in this condition from the discharge end of the cartoning machine to the present apparatus for final drying and seal- 1ng.

In order to dry and seal the flaps at both ends concurrently, the sealing apparatus embodies a pair of parallel conveyor runs which advance continuouslyin unison and carry the heat exchange elements, the cartons.

being engaged endwisely between the two conveyor runs. The receiving end of the conveyor runs arecontiguous to the discharge end of the cartoning machine, such that the folded and glued flaps are immediately engaged by the heating elements under sufiicient pressure to hold them firmly closed and to advance them by frictional engagement while the elements transfer heat to the flaps. carried out as the cartons are advanced between the heating elements and reach the discharge end of the conveyor runs permanently dried and sealed.

The heat exchange elements preferably consist of flat the ends of the cartons. The heat stored in the slats metal bars having a mass to absorb suflicient heat energy to dry the glue by heat transfer while engaging is transmitted by direct conduction to the flaps and From the foregoing, it will be recognized that one of the features of the invention consists in taking advantage of the natural heat absorbing and transferring action of the metal slats to apply maximum heat to the freshly glued flaps when the moisture content is greatest, the slat temperature gradually decreasing as heat The drying process is therefore progressively v 2,930,175 i-PatentedMar. .29, 1960 is exchanged during the drying process. Thisaction drives off the moisture as rapidly as possible while at the same time avoiding excessive heat which may lead to deterioration ing.

The invention further takes advantage of the heat exchange principle to provide an exceptionally simple mechanism. In other words, the heat exchange slats allow the use of stationary heating elements, such that the heat is absorbed and stored by the moving slats, then transmitted to the flaps. This avoids mounting the heatingelements themselves on the conveyor runs with the attendant apparatus to conduct the heat to them as they advance.

In the structure which illustrates the practical appli-' cation of these principles, two self-contained heat transfer conveyors are mounted parallel with one another, each conveyor including an endless conveyor chain carrying metal heat exchange slats which advance along opposed carton-scaling runs and return runs. Each conveyor includes a stationary heating section extending along the return run to heat the returning slats. The parallel conveyor chains advance at uniform speeds around idler sprocketsat the receiving end and thus delineate a converging carton receiving throat leading to the carton-. The cartons are advanced into the con-' tuation of the adjustment mechanism changes the spacing of the opposed slats along the carton-sealing runs.

According to the present disclosure, the sealing apparatus is driven independently of the cartoning machine by its own variable speed driving mechanism which advances both conveyor chains at a uniform rate. The

variable speed mechanism'allows the rate of conveyor advancement to be regulated to conform to the output- Moreover, should the carofthe cartoning machine. toning machine stop for any reason, the sealing apparatus continues operating so'as to unload itself. This pre vents build-up of excessive heat with attendant damage to the cartons and also prevents overheating of the heat;

exchange elements. The transverse adjustment and the speed regulation makes it possible to adapt the apparatus practically to any operating condition which may be encountered.

The present apparatus is intended for use inconjunction with the high speed article feeding apparatus disclosed in my co-pending application, Serial No. 576,096, filed on April 4, 6, now'PatentNo. 2,805,755. The

feeding apparatus disclosed in the patent advances the articles in group formation to the intake end of a car-- toning machine which inserts the groups of articles into I cartons, applies adhesive .to the carton'fiaps, then folds the flaps one upon the other. At its discharge end, the cartoningmechanism advances the cartons betweenbelt runs with the freshly glued flaps held in closed position for'transfer to the receiving end of the present drying I .and sealing apparatus. Although the invention is disclo'sed in relation "to a. carton having overlapping glued 'fiaps at opposite ends,;. it will be understood that the sealing principles are in, tended to. be applied to various other types of cartons "and to various types of heat sensitive adhesive. l

of the. paper board flaps or adhesive coat- 3 The various features of the invention will be more fully understood by those skilled in the art from the fol.- lowing detailed disclosure in conjunction with the attached drawings. In the drawings: i

Figures '1-and 2 illustrate the'flap sealing apparatus as viewedfrom the side, Figure-1" representing the receiving portion'and Figure 2 representingthedischarge portion of the apparatus. The full length side view has been divided lengthwise and placed one above the other=to better illustrate the mechanism.

Figures 3 and 4 illustrate the apparatus in plan view, the'two sections likewise being-placed one above the other.

Figure 5 is an enlarged cross section taken along line 55. of Figure 1. .5

Figure 6 is a sectional view taken along line 6.-6 of Figure 2, illustrating the variable speed driving-system of the een eyor chains. v a

figu e-7 is a perspective view of a carton with the flaps open and adhesive applied, ready for folding.

- Figure 8 is .a perspective view showing :the carton in closed position as it issues from the cartoning machine and enters the receiving end of the sealing apparatus.

General arrangement Referring to Figures 3 and 4, the drying apparatus comprises a pair of longitudinal heat transfer conveyor assemblies, indicated generally at 1 and 2, which extend parallel with one another and delineate the longitudinal carton way indicated at 3. Each heat transfer conveyor is a self-contained unit and includes a continuously"advancing, endless chain loop 4 carrying closely spaced vertical heat exchange slats 5 which engage the cartons-6 endwisely along the way 3 and apply heat and controlled pressure to the freshly glued and folded end flaps. The carton-engaging conveyor runs 7, along the carton way 3, advance at uniform speed in the direction indicated by the arrow from the receiving end 8 to the discharge end 10 of the apparatus. The chains of both conveyors are driven from a variable speed driving unit 11, as explained later in detail.

As the chain runs advance, they carry the heat exchange cleats or slats 5 around the driving sprockets 12 "at the discharge end, thus disengaging the sealed cartons. Thereafter, the slats are advanced alongthe return runs 13 where they are presented to the stationary heating' elements 14 in the direction indicated by the arrows, thus progressively raising the temperature of the slatsas they approach the receiving end 8. At this point, the heated slats pass around the idler sprockets 15 and thus delineate the converging receiving end 8 which engages progressively the opposite end flaps as the closed carton issues from the cartoning machine.

It will be observed that the temperature of the slats is at maximum when they engage the cartons at the receiving end so as to drive off the moisture from the adhesive most rapidly while the moisture content is greatest. Thereafter, as the heat stored in the slats is absorbed into the glued flaps, the slat' temperature progressively decreases. Accordingly, the drying temperature may be relatively high to carry out the treatment in the shortest possible time, while at the same time, avoidingdamage to the flaps orto the adhesive due to overheating. The rate of advancement of the heat exchange slats, combined with the length of the conveyor apparatus, provides a drying period of sufficient duration to dry and seal the flaps completely before the cartons reach thedischarge end.

According to the present example, electrical heating elements 14 are utilizedto heat the slats. These elements extend lengthwise for approirimat'ely half the length of theapparatus, as shown in Figures 3 and 4, and provide sufficient heat for efficient operation. The heating elements are mounted instationar'y position and have flat 4 faces contiguous to the fiat faces of the returning slats as shown in Figure 5.-

The lineal advancement of the two chain loops 4 is made to correspond to the output of the cartoning machine by regulation of the power unit 11. The slats along the way 3 engage the glued flaps under sufiicient pressure to hold them firmly in closed position and to advance the cartons by frictional engagement while the weight load of the cartons is carried by the longitudinal support rails 16. In order to accommodate cartons having different lengths and also to regulate the pressure of the slats against the carton, the two self-contained heat transfer conveyor units 1 and 2 are shiftable transversely relative to one another. In the present embodiment, the conveyor 1 is permanently attached to the frame26, while the conveyor 2 is shiftable transversely upon the frame by a hand-operated adjustment mechanism which is indicated generally at 17, operated by a crank 18. This mechanism includes a series of threaded shafts journalled'in the frame and extending crosswise in threaded engagement with the shiftable conveyor 2 at a series of points spaced along its length. The adjustment crank 18 is in driving connection with all of the threaded cross shafts so as to shift the conveyor 2 uniformly along its full length. As explained later in detail, all components of the adjustable conveyor 2 are mounted upon shiftable brackets slidably carried upon cross members of the frame and in threaded connection with-the cross adjustment shafts.

--Referring to Figure 3, the cartons 6 are delivered from the cartoning machine by the parallel belt runs 20. The ends of the belt runs 20 pass around rollers 21 located adjacent the idler sprockets 15, such that the cartons are transferred with their freshly glued flaps held in folded position. It will be understood that the delivery apparatus will vary according to the design of the cartoner and that the sealing'apparatus may be adapted to any machine which delivers the carton in this condition.

Referring to Figure 7, which illustrates the type of 'carton for which the machine is intended, the carton 6 is formed of the usual paperboard material and includes upper and lower flaps 22 and a pair of inner fiaps 23. This carton is extensively used in packaging canned beer and is of the twelve-can size. The cartoning mechanism, as disclosed in the co-pending applications, is arranged by suitable adjustment to handle either the twelve-can carton or the shorter six-can carton. The adjustment mechanism 17 accommodates the sealing mechanism to both carton sizes as described later in detail.

During passage of the carton through the cartoning mechanism, the group of cans is shifted endwisely into the carton, then the inner flaps 23 are folded to the closed position shown in Figure 7. The upper and lower flaps 22 remain in the vertical position during passage through a gluing station which applies the coating of wet glue 24 to the flaps. Thereafter, the glued flaps are folded over upon the inner flaps 23 as show in Figure 8, then the carton is discharged into the drying apparatus.

The liquid glue or adhesive coating 24 may be of any conventional type best suited to the composition of the paper-board material of the carton, for example, a waterbase vegetable glue. It may also consist of a synthetic adhesive material of a type which satisfies the operating conditions of the drying apparatus.

The chain runs of the drying apparatus advance at a lineal rate corresponding to the output of the cartoning machine, for example, 120 cartons per minute. Accord ing to the present example, the heat exchange slats 5 are heated to a temperature between 250 and 300 degrees F. at the receiving end. The temperature is controlled 'by a thermostat (not shown) which maintains heating elements 14 at the desired temperature constantly. The most etficient drying'temperature depends on the carton material and composition of the adhesive and is obtained by regulating the thermostat to obtain the bestresults under operating conditions. Under normal operating conditions, each carton is advanced through thefdrying' apparatus rapidly, for example in 20 seconds or less and is discharged ready for shipment or sale.

Structural details To prevent interference between the slats and cartons as the slats pass around the sprockets at the intake throat, the leading edges of the slats, as indicated at 5a in Figure 3, may be beveled or curved to conform generally to the of the machine by a cross member 25 in the form of a channel, the ends of the angle irons being connected to the channel by brackets 28. Channel 25 represents the end framing member of the cartoning machine to which the drying apparatus is intended. The frame further includes a series of intermediate cross bars 30 spaced apart from one another along the frame and attached permanently to the angle irons. A support post 31 braces the frame at a point intermediate its length.

At the discharge end of the dryer, there is provided a cross plate 32 having a cross groove for mounting the bearing brackets 33-33 of the drive sprockets 12. Each driving sprocket is keyed to a vertical shaft 34 and these shafts in turn are driven in unison by the variable speed unit 11.

The driving system of the chain runs is best shown in Figure 6. The motor 35 of unit 11 is mounted upon a sliding base 36 and is shifted by a hand wheel 37 relative to the variable sheave 38 to obtain the desired conveyor speed. The motor sheave (not shown) is connected by a belt 40 to sheave 38; this arrangement is conventional and well understood in the art. The sheave 38 is mounted upon a worm shaft 41 journalled in a wormtbox 42 attached to the cross plate 32. The shaft 41 includes a worm 43 meshing with a worm wheel 44 keyed to a cross shaft 45. Shaft 45 has its opposite ends journalled in bearings 46 projecting downwardly from the bearing brackets 33. Each vertical sprocket shaft 34 includes a bevel gear 47 meshing with a respective bevel gear 48 of cross shaft 45; therefore, shaft 45 rotates the driving sprockets in opposite directions as indicated by the arrows in Figure 4, so as to advance the inner cartonengaging runs 7 at uniform speed in the same direction. Adjustment of hand wheel 37 thus varies the speed of both conveyor sprockets and permits the conveyor speed to be regulated to suit the operating speed of the cartoning machine.

The idler sprockets 15 at the rceiving end of the conveyor are mounted on stub shafts 50 journalled in bearing brackets 51. The bearing brackets are slidably engaged in a cross groove formed in the cross plate 52, at thereceiving end. This is similar to that described with reference to the driving sprockets 12.

As noted earlier, the self-contained heat exchange conveyor 2 is adjustable laterally with respect to the conveyor unit 1. For this purpose, all components of conveyor 2 are carried upon intermediate slide brackets 53 carried on the intermediate cross bars 30. As shown in Figure 5, the adjustable conveyor 2 is shiftable from the position shown in full lines (twelve-can carton) to the position shown by the broken line 54, which represents the end of the six-can carton. Upon making this adjustment, the slide brackets 53 of conveyor 2 are shifted inwardly along their cross bars 30 and the bearing brackets 33 and 51 are shifted along their cross plates 32 and 52.

The conveyor units l and 2 are in duplicate, both being carried by duplicate slide brackets and bearing brackets attached rigidly to the cross members. Referring to-Figure'fi, each slide bracket 53 comprises a base plate: 55 having an .inner lug 56 supporting the longitudinal slide bar 16, a second lug 57 supporting the inner chain run 7, and an outer lug'58 supporting the return chain run 13. The three'lugs are connected together by a web 60. The second lug 57 of each bracket is joined to a chain support plate 61 extending for the full length of each chain run. Plate 61 includes a tracking rail 62 along its upper edge having .a groove engaging the flange 63 of a series of support rollers 64 journalled upon the upper end of the heat exchange slats 5. As shown in Figure 3, the chain runs include a sufficient number of support rollers 64 to sustain the runs without imposing vertical pressure, upon the chain links. The chain links are conventional and track against a backing rail 65 alsosecured to the'plate 61.. As shown,

each chain link is provided with a heating slat,the links having brackets 66 secured to the slats. The outward thrust of the slats is carried by the bearing strips 67-67, the upper strip being attached to the tracking rail 62 and the lower strip being attached to a rail 68. The several rails extend for the full length of the conveyor as shown in Figures 3 and 4, suchthat the pressure of the heating slats is transmitted to the brackets 53 outwardly, the bearing strips providing a smooth sliding surface for the slats. 1

It will be noted at this point, that the, base of each intermediate slide bracket53 of conveyor 2 is secured by screws 70 threaded into the cross bar 30. To providev transverse adjustment, each base plate 55 of the bracket includes slots 71 traversed by the, screws. These bolts are loosened when it is necessary to adjust the conveyor 2.

Each intermediate bracket .53 of conveyor 2 further includes a downwardly depending lug 72 which is traversed by a screw shaft 73 of the adjustment mechanism, so as to shift the bracket laterally when the screw is rotated (Figure 5). As best shown in Figures 1 and 2, the several screw shafts are rotated in. unison by respective pairs of sprockets 74, each adjacent pair of sprockets being connected by chain loops 75 for rotating the shafts in the same direction.

As shown in Figure 5, each adjustment shaft has its ment crank 18. As viewed in Figure 1, the chain loops 75 extend from the two sprockets of the crank shaftand transmit the drive to the two shafts on opposite sides of the crank driven shaft; from the two adjoining shafts, the I drive is carried by similar chain loops to the adjustment.

shafts of the remaining brackets. This mechanism shifts all of the slide brackets uniformly in the same direction upon operation of the crank.

The longitudinal slide rails 16, as noted earlier, are

attached in common to all of the slide brackets; hence, the rail 16 and slide brackets shift as a unit when the.

adjustment mechanism is actuated. Referring to Figures 3 and 4, it will be. noted that the longitudinal rails 16 project outwardly to. the bearing brackets 33 at the: discharge end and to thebearin'g brackets 51 at the receiv- 'ing end. As shown in-Figure 6, the bearing brackets 33 at the discharge end' include lugs 81 attached to the endwise extensions of the longitudinal slide rails 15. The

bearing brackets 51 atthe receivingend.include-similar The adjustment 'shafts of the several slide brackets are identical except that the shaft shown in Figure 5 has an endwise extension to receive the adjust-.

'7 lugs 81 connected to the end of the rails 16; therefore, the adjustment motion of conveyor 2 is carried to its slid able bearin'g'brackets by the longitudinal slide rail 16.

It will benote'd'in' Figure 6, that the'shiftable bearing bracket 33 of. conveyor.2 'isheld in position by' holddown screws 82 similar to the screws 70 of the'slide brackets 53; In a similar manner, thebracket includes slots 83, the screws passing through the slots and threaded into the cross plate 32, permitting transverse shifting of the bearing brackets when the screws are loosened. Slide bearing bracket 33 further includes a tongue 84 engaged in the cross groove 85 of its cross plate 32; The keyed connection prevents longitudinal displacement of the bearing bracket under chain tension when the screws 82 are loosened and also guides the bearing bracket smoothly as it is shifted. i

Referring again to Figure 6, it will be noted that the downwardly depending boss 86 of the slidable bearing bracket passes through a cross slot 87 in its cross plate 32 to permit transverse shifting; To permit the bevel gear 48 of cross shaft 45 to shift with the bearing bracket, the bevel gear slidably engages an elongated key 88 fixed in the end portion of the cross shaft. The bevel gear remains in mesh with its companion bevel gear 47 and remains keyed to the cross shaft upon adjustment.

The adjustable bearing bracket 51 at the receiving end is slidably mounted upon its cross plate 52 in substantially the same manner, including the hold-down screws 32 which are loosened to permit adjustment. The bracket also includes a tongue 84 slidably keyed in the groove 85 of its cross plate. Since the arrangement is substantially the same as that of the discharge end, the structure has not been illustrated in detail.

The transverse adjustment range of the slidable brackets and bearings of conveyor unit 2 is sufiicient to bring the heat exchange slats to the plane of the broken line 54 (Figure which represents the end of a six-can carton, as noted earlier. It will also be recognized that the adjustment mechanism permits precise regulation of the pressure applied against the opposite ends of the cartons in order to obtain the best operating conditions.

As pointed out earlier, the components of the fixed conveyor unit 1 are similar to those of conveyor'units 2. Since the unit is fixed, the several slots are omitted and the brackets are attached rigidly by screws '70 and 82 threaded into the cross members of the brackets, the adjustment shafts 73 and lugs 72 being omitted.

The return run 13 of each conveyor loop is supported upon tracking rail 90 engaging the rollers 64 and having a groove engaging theflange .63 as described with reference to the carton-engaging run 7. Rail 90 is right angular in cross section and its lower portion includes a backing rail 91 engaging the rollers of the chain links. This structure guides the returning chain runs and slats in a plane contiguous to the flat faces of the heating elements 14.

As shown in Figures 1 and 3, the two conveyor assemblies each include a slack control sprocket 92 which is spring urged outwardly to maintain the chain loop in taut condition. Sincethe chain loops expand lengthwise as they are heated 'to operating temperature, the spring loaded sprockets take up the slackwhich would otherwise prevail. Described in detail, each sprocket is journalled upon astub shaft 93 mounted in the swinging end of a tension arm 94. The opposite end-of each tension arm is pivoted upon a shaft 95 attached to a bar 96 projecting outwardly from the longitudinal slide rail 16. The lower end of shaft 95 has a counter-turned screw threaded portion passing through the bar and engaged by a nut 97, locking the shaft against rotation in thebar and leaving the tensio'n'arin94'free" to pivot. The shaft projects upwardly and carries a torsion spring 98 having its upper and anchored to a collar 100 pinned to the shaft. The torsion springs are preloadedto urge the tension arms outwardly 'under the required pressure.

Since the mounting bars 96 are attached to the slide rails 16, the sprocket assembly of the shiftable conveyor 2 moves with the conveyor when an adjustment is made.

According to the present example shown in Figure 5, each chain run is heated by two parallel rows of heating elements 14 mounted in a common vertical plane in end-to-end relationship." 'Each element is carried by pairs of spacer rods 101 projecting from opposite ends of the elements. The spacer rods are secured to respective angle brackets 102 attached to the mounting bracket 53, the angle brackets being in the form of right angular plates as viewed in Figure 5, thereby partially surrounding the return chain runs and heating elements. The ends of the angle brackets are attached to the base and outer lug of the mounting brackets 53, thus supporting the heating elements firmly in position. Electrical energy is supplied to the heating elements by the usual cable system having heat regulating thermostats (not shown) interposed in the circuit for heat control. Since the heating elements are carried directly upon the slide brackets 53, the components all shift without interference upon adjustment of conveyor unit 2.

As viewed in Figure 5, two rows of heating elements provide a heating area extending for the full length of the heat exchange slats 5, each element having a flat face 103 presented to the surface of the slats. The fiat faces of the heating elements are located contiguous to the fiat heat exchange slats and the tracking rails guide the returning slats accurately along the heating plane;

ltwill be noted that the flat faces of the heating elements and slats have an area substantially equal to the endwise area of the cartons, such that the entire fiap area is heated uniformly during the drying process. In the present example, the slats are formed of stainless steel to inhibit oxidation and preserve the efficiency of the apparatus.

As indicated in broken lines (Figure 5), the heat exchange conveyors 2 preferably are provided with guards 34 partially surrounding the heating elements to protect the operator. The guards 104 are generally right angular in cross section corresponding to the cross section of the angle brackets 102 and extend for the full length of the apparatus. The inner surface of the guards includes a liner of heat insulating material, such as asbestos, to prevent the exposed guards from becoming hot. The guards further conserve heat since they partially enclose the heating elements and shield them from air currents.

Having described my invention, I claim:

1. An apparatus for sealing a carton having closure flaps which form opposed walls thereof, said flaps overlapping one another in closed position and having heat sealing adhesive therebetween, said apparatus comprising a frame, a' pair of self-contained longitudinal heat transfer conveyor units shiftably mounted in a substantially horizontal plane and in parallel relationship upon said frame, adjustment means connected to at least one of said conveyor units for shifting the same transversely upon said frame relative to one another, each of said conveyor units having an endless conveyor chain including a series of heat exchange elements residing in a sub stantially vertical plane, said endless conveyor chains having opposed carton-engaging runs and respective return runs, said adjustment means locating said opposed heat exchange elements along said carton-engaging runs at a spacing to embrace the opposed closure flaps of the carton, said heat exchange elements holding said flaps in closed position, driving means connected to said conveyor chains for advancing the heat exchange elements inthe same direction along the carton-engaging runs, thereby advancing the carton along said runs, respective heating means mounted upon said conveyor units along said return runs adjacent the heat exchange elements, said heating means residing adjacent the heat exchange elements on the side opposite the conveyor chain thereof, said heating means transmitting heat to said elements and conveyor chains during advancement along said return runs for transfer to said closure flaps during advancement of the carton along the cartonengaging runs, said heating means shifting transversely in unison with the conveyor unit upon adjustment thereof by said adjustment means, a respective slack control element mounted on each of said self-contained conveyor units and engaging the endless conveyor chain thereof, and resilient means connected to said slack control elements urging the same against said endless conveyor chains in a direction to keep said chains in taut condition, said slack control elements yielding in response to expansion and contraction of the conveyor chains upon heating and cooling thereof.

2. An apparatus for sealing cartons having closure flaps at opposed walls thereof, said fiaps overlapping one another and having a heat sealing adhesive therebetween, said apparatus comprising a frame, a pair of endless conveyor chains extending parallel with one another along said frame, said chains having vertically disposed heat exchange elements thereof and having opposed carton-sealing runs and respective return runs, each conveyor having sprockets at opposite ends thereof, said conveyor chains trained over said sprockets, respective bearing brackets on said frame and journalling each of said sprockets, a longitudinal guide rail having opposite ends secured to the bearing brackets of each conveyor chain and extending along said carton-sealing runs in a plane to contact the bottom of a carton advancing along said runs, the bearing brackets of one conveyor chain being shiftable transversely relative to the other, adjustment means connected to the longitudinal guide rail for moving the guide rail and shiftable bearing brackets 35 2,727,345

transversely, thereby to locate the conveyor chains-and opposed heat exchange elements at a spacing to embrace the opposed flaps of a carton along said carton-sealing runs, driving means connected to a sprocket of each conveyor chain for advancing the heat exchange elements in the same direction along said carton-sealing runs, and heat transmitting means mounted in fixed position relative to said guide rails and located along said return runs adjacent the heat exchange elements on the side opposite the conveyor chain thereof, said heat transmitting means transmitting heat to the heat exchange elements, the said adjustment means regulating the pressure imposed by said heat exchange elements upon the opposed flaps of the carton along said carton-sealing runs, said heat transmitting means shifting in unison with said longitudinal guide rails upon transverse adjustment of said rail and bracket by said adjustment means, said heat exchange elements absorbing heat from the heat transmitting means during advancement along the return runs and transmitting heat and pressure to the opposed flaps to seal the carton during advancement along the carton-sealing runs.

References Cited in the file of this patent UNITED STATES PATENTS 1,329,069 Bevier Jan. 27, 1920 1,840,410 Robinson Jan. 12, 1932 1,854,075 Smith et a1. Apr. 12, 1932 1,887,699 Reid Nov. 15, 1932 2,107,249 Hepke Feb. 1, 1938 2,133,348 Ferenci Oct. 18, 1938 2,263,691 Enkur Nov. 25, 1941 2,346,776 Malhiot Apr. 18, 1944 2,617,240 Monaco Nov. 11, 1952 Schoppee Dec. 20, 1955

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