US3114226A

US3114226A - Apparatus for heat sealing

Info

Publication number: US3114226A
Application number: US87632A
Authority: US
Inventors: Robert E Taggart; William S Becher
Original assignee: American Can Co
Current assignee: Primerica Inc
Priority date: 1961-02-07
Filing date: 1961-02-07
Publication date: 1963-12-17
Anticipated expiration: 1980-12-17

Description

R. E. TAGGART ETAL 3,114,226

APPARATUS FOR HEAT SEALING Dec. 17, 1963 INVENTORS. WILLIAM S. BECHEP 6 Sheets-Sheet 1 Filed Feb. 7, 1961 y ROBERT DTAGGART W575 1963 R. E. TAGGART ETAL 3,1 4,226

APPARATUS FOR HEAT SEALING Filed Feb. 7. 1961 6 Sheets-Sheet 2 INVEVTOR. WILLIAM J. BEOHER ROBERT E. TAGGART 4;; ATTORNEY-S Dec. 17, 1963 R. E. TAGGART ETAL 3,114,226

APPARATUS FOR HEAT SEALING Filed Feb. 7, 1961 6 Sheets-Sheet 3 I I 'I. "I I I I. I I I I L Izs 9 Q Hi III 7 m E-L' I55 I23 II has I II. II III II. I

I I i l I INVENTOR.

WILLIAM a. BEOHER ROBERT a'rAecmr ATTOENEYS Dec. 17, 1963 R. E. TAGGART ETAL 3, 4, 2

APPARATUS FOR HEAT SEALING Filed Feb. 7, 1961 s Sheets-Sheet 4 I I I u /0"" "In I l I.

VINVENTORH WILLIAM .s. BECHER ROBERT E. TAGGART A TTOENfYS Dec. 17, 1963 R. E. TAGGART ETAL 3,114,226

APPARATUS FOR HEAT SEALING 6 Sheets-Shea}. 5

Filed Feb. 7, 1961 INVENTOR. WILLIAM S. BECHER ROBERT E. TAGGART ATTORNEY? 1963 R. E. TAGGART ETAL 3, 14, 5

APPARATUS FOR HEAT SEALING 6 Sheets-Sheet 6 Filed Feb. 7, 1961 WILLIAM S. BECHER ROBERT E. TAGGART United States Patent 3,114,226 APPARATUS FOR HEAT SEALING Robert E. Taggart and William S. Becher, Appleton, Wrs., assignors to American Can Company, Jersey City, N.J., a corporation of New Jersey Filed Feb. 7, 1961, Ser. No. 87,632 2 Claims. (Cl. 53-375) This invention relates to an apparatus and method for heat-sealing articles coated wtih thermoplastic materials. Although the apparatus and method can be used in connection with a variety of heatsealing operations involving use of thermoplastic materials, the invention will be de scribed as embodied in an apparatus and method for heatsealing paperboard cartons, such as used for the packaging of ice cream.

. Ice cream is customarily packaged in cartons employing conventional end locking means or in cylindrical containers, both of which present certain deficiencies. The use of locking means involves greater detail in die cutting for the blank than does a carton composed of all essentially rectangular panels. If the locking means is improperly cut or distorted, the carton may open prematurely prior to use by the purchaser. The use of a cylindrical container is uneconomical in regard to storage space both for the seller of the packaged ice cream and theconsumer. Furthermore, the cylindrical package does not readily lend itself to equal division of the contents by slicing as does a square package.

From the standpoint of storage space, utility and convenience, the ideal packaging means is a parallelepiped, V

heatsealed carton with a glued or permanent lock type opening feature. Such a carton is essentially tamperproof since the tearing of either the heatseal or the opening feature is readily ascertainable. A typical sealed end carton has essentially the same size and shape as the conventional locked end carton, namely, that shown in FIG- URE 4 of US. Patent No. 2,760,713. As is readily ascertainable from examination of that drawing, the length along the longitudinal edge of the carton is substantially greater than the height. Since when removing the contents from the end of the carton the hand must penetrate further than when removing the contents through the top, the chance of getting ice cream on the hand is greatly increased. The use of heatsealed end flaps in place of the locking flaps of the patent discourages the end opening of the carton, and conversely encourages removal of the contents through the larger top opening, which is in fact more convenient.

Heretofore, the use of heatsealed cartons has been limited by the fact that it is diflicult to obtain a proper seal between the desired surfaces without detrimental side effects to the carton. In order to obtain proper adhesion the thermoplastic adhesive must be completely melted and evenly distributed between the surfaces. The heat for melting is transmitted through the flaps to the coated surfaces which are in contact with each other. Application of suflicient heat for a prolonged period to melt the adhesive tends to break down the thermoplastic material, produce scorching and degrade the overall outside appearance of the package surfaces. The use of pressure in conjunction with heat permits sealing at a lower temperature and with a shorter operating time. Attempts to obviate the above difliculties have therefore included pressure applied in the proper area in conjunction with heat.

Although the use of pressure as well as heat for heatsealing is of the utmost importance, prior sealing utilizing both elements has been limited. The main problems involved are those of having a suitable base to absorb the pressure of the sealing bar or roll and the danger of degradation and scorching of the carton surfaces. Since the ice cream when loaded into a carton is fluid, it will 3,114,226 Patented Dec. 17, 1963 ice not resist strongly the inward movement of the end flaps of the carton when pressure is applied to them. The only portions of the carton that provide backing support are the end edges of the top, bottom and side walls, but this has proved insuflicient since there is not enough of the end flaps abutting them to assure adhesion or else the walls themselves may buckle and be distorted by the pressure applied.

Prior attempts to solve the problem of providing sufficient backing support to withstand the pressure of the sealing bar or roll employed back up blades, plates or mandrels as described in US. Patent 2,524,032. When employing a plate as described in the patent, one pair of opposed flaps previously coated with a thermoplastic adhesive is infolded to overlie the plate. Heat is applied by an element in contact with the exposed flap surface. The underlying blade or plate is externally supported, providing a reinforcing surface, sothat simultaneously with the application of heat, the flaps interposed between the two surfaces are compressed by the pressure applied. This procedure is not well suited to continuous operation since each carton is handled manually and individually and therefore has a limited application. Furthermore, when the sealing is accomplished in one step, detrimental side effects such as scorching, degradation of carton surfaces etc., are still a problem.

The general object of the present invention is to provide an apparatus for continuously heatsealing thermoplastic coated sheets and especially for rapid, efficient sealing of paperboard cartons without affecting the exposed external surface of the finished carton.

Another object of the present invention is to continuously heatseal a carton without destroying or distorting the shape of the squared carton shell.

Another object of the present invention is to provide a method of continuously heatsealing thermoplastic coated sheets which avoids overheating of the coated surfaces.

Another object of the present invention is to provide a heatsealing apparatus that is adaptable for use with a variety of carton erecting and filling machinery.

Another object of the present invention is to provide an apparatus that is adjustable to seal according to the rate of influx of the packages into the sealing area.

Another object of the present invention is to provide an integral means for consecutively heatsealing and cooling a flow of successive filled cartons.

Another object of the present invention is to provide a method and apparatus for heatsealing thermoplastic coated surfaces of a type to avoid gumming and coating of parts with the adhesive employed.

Yet another object of the present invention is to pro vide an apparatus such that there is no scorching of the coated material due to disruption of the continuous operation.

Still another object of the present invention is to provide a continuous process of filling and sealing so as to eliminate manual handling of the cartons.

A further object of the invention is to provide a method and apparatus for continuously heatsealing thermoplastic coated materials whereby there is no movement of the'materials during the application of heat and pressure for sealing, and no application of heat and pressure for sealing during movement of the materials to a subsequent position.

The above objects are accomplished by passing a thermoplastic coated article through successive alternate steps of advancing the article along a path of motion, applying heat and pressure to the article, again advancing the article, and cooling the sealed surfaces. Each of the above steps is repeated a number of times so that there may be several sealing and cooling steps applied to each article with the steps spaced by intermittent periods of aliases 3 advancing the article forward from the heating section to and through the cooling section. During the heating and cooling steps the pressure is applied against the article surfaces to be sealed together by compressing the surfaces between a pressure applying means and a pressure absorbing means.

Further details, advantages and objects of the invention will be apparent from the following specification and appended drawings wherein;

FIGURE 1 is a side elevation view of an ice cream carton filling machine and the heatsealing unit embodying one form of the invention,

FIGURE 2 is a fragmentary perspective view of the heat sealing unit and its attachment to the filling machine,

FIGURE 3 is a fragmentary sectional view of the nozzle head of the filling machine taken along line IIIIII of FIGURE 1,

FIGURE 4 is a fragmentary sectional view of the yoke of the filling machine and its connection taken along line I'v rv of FIGURE 1,

FIGURE 5 is a fragmentary perspective view of the structure for opening and then closing the bottom flaps of the carton,

FIGURE 6 is a fragmentary perspective view of the carton indexing means and closing means,

FIGURE 7 is a fragmentary sectional view of the sealing unit during a sealing step, taken along line VIIVII of FIGURE 1, 7

FIGURE 8 is a fragmentary sectional view of the sealing unit during an indexing step, taken along line VIIIVIII of FIGURE 1,

FIGURE 9 is a fragmentary perspective view of the underside of the sealing unit showing the position of the heater-cooler-bar and linkage during the indexing step,

FIGURE 10 is a fragmentary perspective view of the sealer-cooler-bar and linkage during a sealing step,

FIGURE 11 is a perspective view of the upper sealercooler-bar with the cover plate removed,

FIGURE 12 is a fragmentary perspective view of the heatsealing unit embodying another form of the invention and its attachment to the filling machine,

FIGURE 13 is a fragmentary perspective view of the underside of the embodiment of FIGURE 12,

FIGURE 14 is a perspective view of the upper sealercooler-bar of the embodiment of FIGURE 12 with the cover plate removed, and

FIGURE 15 is a perspective view of a typical glued, and squared carton shell suitable for use with this invention.

Referring first to FIGURE 1, there is shown an ice cream carton filling machine, unit A, and aligned therewith and attached by a tie plate, a heatsealing attachment, unit B. The filling machine described, unit A, in the following embodiment and attached to the heatsealing attachment, unit B, is the Model 55, half gallon machine produced by Anderson Brothers Manufacturing Company of Rockford, Illinois.

The filling machine is conventional and constitutes no part of the invention. Although the heatsealing attachment is designed primarily to work in conjunction with the filling machine shown and hereinafter described, it is understood that with minor modifications to the unit and without changing its operating principles it can be employed with other carton filling machines.

Initially, the carton blanks are folded and glued so that they are in the form of collapsed shells, essentially as disclosed in aforesaid Patent 2,760,713. A stack of cartons in this form is placed in the carton hopper of unit A so that the side edges are vertical and the cartons are parallel to the way assemblies 23. The glued carton shells are successively fed from the hopper 29, squared into rectangular form, and the end flaps separated by conventional means including mechanical slicer fingers which are positioned between the way assemblies 23 below the point indicated at 22, carton opener 21, and carton breaker 24. Next, a squaring arm (not shown) grasps the carton shell and draws it across and squares it between way assemblies 23. FIGURE 15 shows a typical glued and squared carton shell with the flaps extended. The arrow indicates the direction of motion of the carton shell as it is advanced forward for filling and sealing. The flaps and panels have been numbered to clarify the explanation of the packaging operation.

As the carton advances, the upper forward and trailing end flaps 4 and 2, respectively, which are lying horizontal, pass under the hold down bar 25 which maintains them in that position until they reach the nozzle head 30. At this time the upper side fiaps I and 3 of the carton shell, which are extended vertically, lie in planes parallel to way assemblies 23. Lower flap lifter 26 folds in the bottom trailing flap It before folder 2'7 forces the bottom forward flap 12 into horizontal, subposed relationship with the bottom trailing flap It The

bottom side fiaps

9 and 11 are then folded inwardly into horizontal overlapping relationship by the lower iiap folding plows 28. In this position with the top flaps ll, 2, 3, 4 open and the bottom flaps 9, 1d, 11, "12, closed, the carton advances to the nozzle or filler head 39. During the time that the squared carton shell traverses the length of the filling machine, the carton shell is maintained in its squared position by the combined action or" the indexing fingers 41 shown in FIG- URE 6 and the pusher blades ift shown in FIGURES 4 and 6. As the carton nears the area under the nozzle or filler head 3t fiap holder 38 engages the bottom of the carton to prevent the reopening of the carton prior to filling. Connectively attached to the hold down bar 25 is the flap weight 31 which moves in a vertical plane. This bar foldsthe upper forward flap 4 down below the horizontal position so that it clears the lower edge of the nozzle head 3% to prevent its infolding into the interior of the squared carton prior to filling. The vertical portion 32 of the hold down bar 25 serves to hold the upper trailing flap 2 down against the outside of the carton when the carton is raised for filling. A horizontal bar 33 attached to vertical portion 32 maintains the proper distance between the upwardly extending upper side flaps I and 3 so that they pass on each side of and do not catch on the nozzle head 3%. When the carton is under the nozzle head, it is raised into position for filling by package lifter The ice cream is fed from an ice cream making machine through a pipe or hose (not shown) to the nozzle head 30 at 29. In order to facilitate filling, the ice cream is in a semi-fluid state and consequently must be hardened after packaging. The carton being filled and the next carton to be filled are maintained in close relationship to prevent leakage when the filling is completed and the cartons are indexed forward.

FIGURE 3 is a cross-sectional view of the nozzle head showing the index-controllingmicro button 35 which is indicated by broken lines in FIGURE 1. The micro button 35 is tripped by carton flap 1 as the carton is raised up around the nozzle head 36, disengaging the drive means located in cabinet 39, which indexes the cartons forward. As the carton is filled, it slowly slides down from the nozzle head due to the weight of the ice cream therein. When the upper edge of tripping flap 1 slides below the micro button 35, the button is released, the drive means is reengaged and the cartons are again indexed forward. The bottom of the filled carton after leaving the nozzle head is supported on package supports 44. These supports are attached to the bottom of the way assemblies 23 After the cartons leave the nozzle head 34 and are indexed forward, nozzle hook 36 lifts the upper lead flap 4 to an angle above the horizontal. The top flap pusher 37 then kicks in the upper trailing flap 2 to lie horizontal on top of the ice cream. Following this the upper flaps and the lower flaps both undergo a series of folding operations.

The upper and lower side flaps I, 3 and 9, 11 respectively, are folded over the upper and lower sealing blades E4 101 and 162 (FIGURE 2), respectively, as the cartons are advanced. These blades form an essential part of the heat sealing unit, providing support for the application of heat and pressure during the sealing step. In order to accomplish the desired folding steps, folding means including folder 27, folding plows 28, flap splitter 160, top folder 193, top folding plows 1194 and 105, top folder plate 106 and folding shoes 107 are employed. As the carton advances, top folder 103 folds in the upper forward flap 4 of the carton. The upper trailing and leading flaps, 2 and 4 are held in horizontal overlapping relationship by portion 10311 of the top folder 103. The upper side flaps 1 and 3 of the carton are folded one at a time over the top sealing blades or pressure absorbing surface 191 which is connected to portion 103a of the top folder. Top flap folding plows 104 and 105are arranged so that side flap 1 adjacent plow 195 is infolded prior to the other side flap 3 which is adjacent plow 104. The closure of the upper side flaps is completed by the top folder plate 106 and folding shoes 107. As the carton leaves the folding shoes 167 the upper leading and trailing flaps 2 and 4 are held under the top sealin blade or pressure absorbing surface 1191 while the upper side flaps 1 and 3 are folded in a horizontal position over the blade or pressure absorbing surface.

leading and trailing

flaps

12 and 10, respectively, are

closed and resting against the package supports 44 and the upper surface 1119a of the flap splitter 100. The

lower side flaps

9 and 11, extend in a generally downward direction and in such a position contact the flap closing plows 10S and 109 shown in detail in FIGURE 5. As the carton advances, flap 9 adjacent plow 168 is infolded first and then the other side flap 11 is infolded to underlap in subposed relationship. Extensions 108a and 1119a of the closing plows maintain the

lower side flaps

9 and 11 in closed position about the bottom sealing blade or pressure absorbing surface 102.

The cartons are advanced into the heatsealing unit by the drive means at 39 of unit A. As shown in FIG- URE 6, indexing fingers 41 move the cartons forward by applying a pushing pressure to the trailing main panel 6 of the carton. These fingers are attached to the pusher blades 40 and are retractable so that they become flush with the inner surface thereof when the pusher blades index backward toward the carton hopper 20. Spring loading causes the fingers 41 to snap out beyond the inner surface of the pusher blades 40 on the backward stroke of the blades as soon as the fingers are past the next preceding carton. The pusher blades then index forward and the cartons are advanced. As the cartons reach the heatsealing unit they are moved forward in abutting relationship supported on lower sealing unit guide bars 111. This is due to the fact that there is no independent drive means located in unit B and hence the only means for advancing the cartons is provided by the cartons coming from unit A.

Drive means located in cabinet 39 are engaged and disengaged by a clutch controlled by the tripping of the micro button 35. The drive means at 39 are connected to the drive bar 42 shown in FIGURE 9 and in crosssection in FIGURE 4. Connected across the end of the drive bar is yoke 43, the upper portions 43a of which extend inwardly through a slot in the way assemblies 23 and are connected to the pusher blades 49.

Therefore, when the micro button 35 is released and the drive means engaged, the drive bar 42 transmits motion through the yoke 43 to the slide plates 40 and the machine indexes the cartons forward. If there is no car- 6 ton under the filling head the drive bars continually move back and forth since there is nothing to trip the micro switch and disengage the drive means.

FIGURE 2 shows the method of attachment of unit A to unit B, the top cover 129 and the guide bars 111 and 112 removed. The frame of unit B is constructed of frame posts 121 with leveling screws 120 attached thereto, frame cross members 122, and frame plate 123. Extending upward from the frame plate 123 are support posts 124. These are connected at the top by horizontal support members 125 which extend transversely to the path of travel of the cartons. The horizontal support members 125 are hingedly connected at 126 to the support posts 124. At the opposite ends the horizontal support members 125 are held in place by rotatable connecting pins 127. Covering the support members is the top cover 122 (shown in FIGURE 1). Extending upward from the frame plate 123 intermediate support posts 124 are lower covers 130.

Upper sealer-cooler bar 146 is suspended from horizontal support members 125 by mounting studs 128.

' FIGURE 11 shows the sealer-cooler bar 140 with the cover plate 141 removed. The lower sealer-cooler bar URE 9. Since both sealer-cooler bars are essentially the same in structure, only the upper sealer-cooler bar will be described in detail. The bar consists essentially of a machined piece of metal 142 and cover plate 141; Slotted

areas

143, 144 and 145 are machined out of the piece 142. Into area 143 is inserted strip heater 146, the lead wires to which are indicated at 147. Below the heater cavity 14-3 another cavity 144 for a thermostat 148 is formed. The lead wires for the thermostat 143 are indicated by 149. At the opposite end-of bar 14%) a machined out portion 145 provides a channel through which cooling water runs countercurrently. Cool incoming water enters at inlet 156) through hose 153 and leaves at a higher temperature (after absorbing heat from the sealed carton flaps) from outlet 151 through hose 154. Surrounding the machined out portion 145 on the cooling end, is gasket 152, which seals the water channel 145 to maintain waterproofness. Changes in heater temperature and water temperature can be made to compensate for a variation in carton residence time in unit B due to fluctuations in the speed of operation of unit A. For example, the sealing temperature usually employed varies from 275 to 475 F. and the entering cooling water varies from 55 to 70 F. at a speed of 15 to 40 cartons per minute. Obviously the greater the speed the higher the required degree of heat for sealing, and consequently the lower the required temperature of the cooling water. Lower sealercooler bar 155 is essentially the same in structure. Thermostat 148, located in the upper bar 140, controls the temperature of both heaters.

The lower sealer-cooler bar 155 is movable about its supporting linkage shown in FIGURE 9, and activated by a solenoid actuated air piston located in cylinder mounted beneath frame plate 123. Piston rod 161 with clevis 162 at the top thereof is connected to actuating lever 163 by connecting pin 164. The actuating lever 163 is connected by connecting pin 165 to lower pillow block 166, which is mounted on frame plate 123. Similarly, toggle link 167 is attached to a lower pillow block 168 by a connecting pin 169. Both actuating lever 163 and toggle link 167 are attached to upper pillow blocks 170 and 171, respectively, by connecting

pins

172 and 173. These upper pillow blocks 170 and 171 are attached to the lower sealer-cooler bar 155. Because of this interconnection, the particular elevation of the sealer-cooler bar 155 is changed by a raising or lowering of the piston rod 161.

Similar to the upper sealer-cooler bar, the water in the lower sealer-cooler bar flows counter-currently to the movement of the cartons. Cooling water enters through 7 inlet 174 from hose 175 and is emitted by outlet 176 through hose 177. The heated portion of the bar has heater lead wires 178 connected thereto adjacent the cooling portion of the bar.

The solenoid-actuating double-acting air piston located in cylinder 160 is motivated by trigger 181 connected to a conventional actuating switch in enclosure 181. As stated previously, the release of micro button 35 engages drive means at 39, imparting motion to drive bar 42 connected at its end as shown in FIGURES 4 and 9 to yoke 43. When the drive bar moves forward the yoke 43 contacts the trigger 18-1). This contact sends an impulse through a relay 1 82 and a conduit 183 to a solenoidoperated air valve 185. The solenoid in the air valve 185 is then actuated so that pressure air enters from the air inlet 184 into the bottom portion of a solenoid actuated air motor 186, forcing the piston rod 161 upward, thus retracting lower sealer-cooler bar 155. This forces the air in the upper portion of the motor 1156 out through the air exhaust ports 187. FIGURE 8 shows a sectional View of the unit during an indexing step with the pressure released, and lower bar 155 retracted from contact with I lower flap 11 of the carton. In this stage, the carton rests on guide bars 111 and also out of contact with upper bar 149.

As the yoke 43 begins its reverse stroke, it again strikes the trigger 139. This again triggers the solenoid in valve 135 so that air again enters from air inlet 184. This time however, the air enters the upper portion of the solenoid actuated air motor 186. The piston rod 161 is forced downwardly and the air in the bottom portion of the motor exhausts through ports 187. When the piston rod is at the bottom end of the motor, the lower sealer-cooler bar has been raised and thereby pressure is applied against top flap 3 by sealing bar 140 and against bottom flap 11 by sealing bar 155, for sealing the cartons. FIGURE 7 shows a sectional view of the unit during this sealing step.

Thus, alternately, pressure is applied to and released from the bottom of the cartons. As the pressure is applied the heated portions of both bars are in pressure contact with the exterior top and bottom flaps of the carton, causing a melting of the adhesive between adjacent overlapped

flaps

1, 3 and 9, 11. The sealing blades 161 and 1112 provide a pressure absorbing surface or backing resisting the pressure of the sealer-cooler bars. Between the blades and bars the overlapping carton flaps are pressed into sealed relationship. After the sealing step, the carton is pressed forward to again go through another sealingstep or, if far enough along, it passes into thecooling portion of the unit which in a corresponding cycle sets the melted adhesive to prevent rupture of the newly formed seal.

The linkage shown in FIGURE 9 employs a single solenoid actuated double acting air piston located in cylinder 160 as the preferred embodiment. However, two air pistons, each located at and connected to one end of the lower sealer-cooler bar can be employed instead of one air piston and the toggle link 167.

Although several of the elements included with the unit B, namely flap splitter 100, sealing blades 1131, 102, upper folder 103, top flap folding plows 104, 1115, top

folder plate 106, folding shoes 107 and flap closing plows' 108, 109 areattached to unit A, they are part of the heatsealing attachment and may be suspended independently of the filling machine. Unit B is aligned with unit A so as to provide a continuous straight path for the advancing cartons. Tie plate 110 connects the units in substantially immovable relationship. Final adjustments are made by means of leveling screws 120.

Reference will now be had to all of the figures as a typical forming, filling and sealing step is described.

A collapsed carton shell is fed in from the carton hopper of unit A shown in FIGURE 1 by means of the mechanical slicer fingers. Carton opener 21, carton breaker 24 and the squaring arm form the cartcn into a squared shell. Next the bottom flaps are closed and the top flaps positioned open, as earlier described, so that they will not interfere with filling. The carton is indexed up to and under the filling head shown in a side view in FIGURE 3 by means at 39 controlled by a micro button 35 located on the nozzle or filler head 30. Next, the carton is raised by a package lifter. As upper side flap 1 rises on the nozzle head it contacts and depresses the micro button 35. This disengages the drive means at 39, stopping the indexing motion. As the carton fills, the filling pressure and/ or weight of the ice cream causes the carton to slip down from the nozzle head 31). This releases the micro button 35 and engages the drive means. Pusher blades 41 move backwards so that the indexing fingers 41 engage the next succeeding carton to move that carton forward into position under the nozzle head.

As the filled carton is moved forward from beneath the nozzle head by the next stroke of pusher blade 40, the bottom side flaps 9 and 11 are reopened by flap splitter 1% as shown in FIGURE 5. They in turn are reclosed by bottom closing plows 1113 and 199 over lower sealing blade 1192 and held in that position by extensions a and Hi /a until they reach the sealing unit guide rods 111. During this time as during the forming and filling steps the advancement of the carton is intermittent due to the microbutton 35 alternately engaging and disengaging the drive means at 39.

As the bottom side flaps are reopened and reclosed the top side flaps 1 and 3 are closed about the upper sealing blade 1111 as shown in FIGURE 6. First the upper trailing fiap 2 is folded in, followed by the upper forward flap 4, and finally the upper side flaps 1 and 3 are infolded so that the upper side flaps overlie the upper sealing blade with flap 3 overlying flap 1. This folding is done by the upper folder 103, top flap folding plows 104, 105, top folder plate 166 and folding shoes 167. At this point the body of the carton is located between the upper and lower sealing blades 1131 and 192.

The carton is now in position to enter the heatsealing attachment, unit B, shown attached to the filling machine unit A (FIGURE 2). During the next indexing step the carton is pushed forward by the next succeeding carton. The cartons are held in line by side sealing unit guide bars 112 and lower sealing unit guide bars 111 shown in FIGURES 7, 8, and 9. When the drive bar 42 moves forward in this step, after the micro button 35 is released, it causes the yoke 43 to contact the trigger 180, of the switch at 181 which then actuates the solenoid in the air valve 185 so that air enters the lower portion of the air motor 186 and air leaves the upper portion of the air motor through air outlets 187. Consequently lower sealer-cooler bar retracts in a downward direction and the pressure on each end of preceding ice cream packages is released. FIGURE 8 is a vertical sectional view of the sealing unit with the pressure thus released. In this position the sealer-cooler bars do not touch the carton, which rests on the lower sealing unit guide bars 111. FIGURE 9 is a perspective view showing the linkage when the lower sealer-cooler bar 155 is retracted.

The carton is then advanced forward farther into the sealing unit by the pressure of succeeding cartons. As the drive bar 42 begins its reverse stroke, the yoke 43 again strikes the trigger which results in a flow of air into the upper end of air motor 186. This lowers the piston rod 161 which raises the lower sealer-cooler bar, lifting the cartons from the sealing unit guide rods 111 and applying pressure to the top and bottom of the carton. FIG- URE 7 is a vertical sectional view of the sealing unit with pressure applied during the sealing step. FIGURE 10 shows in perspective the linkage when pressure is being applied.

The pusher blades 40 continue to move rearward, as mentioned previously, with the fingers 41 springing out so they can seat behind a succeeding carton. The length of the backward stroke or motion is such that there is considerable overtravel with the fingers going farther back than is necessary to seat behind the next succeeding cartons. When the initial forward stroke or indexing motion starts, the pusher blades move an appreciable distance before the extended fingers engage the cartons and move them forward. Consequently, the distance the cartons are advanced is limited and not as great as the distance traveled after a filled carton leaves the nozzle head. The initial forward stroke or indexing motion of the engaged cartons continues until the micro button 35 is again depressed by the flap of a carton being raised around the nozzle head 30. Pressure is applied continuously throughout this period since the yoke 43 does not strike the trigger 180 until it resumes its forward motion after a filled carton leaves the nozzle head. The same cycle is repeated with the carton moving, after several cycles, to the cooling portion of the sealer-cooler bars and thence after several additional cycles out of the heatsealing unit to be collected in any conventional manner. The package is then ready for the freezer so that the somewhat plastic ice cream can be hardened.

Since the sealer-cooler bars as shown in FIGURE 11 are comprised of heating and cooling sections approximately equal in length, the dwell time of a carton in each portion of the bars will be about the same. Further, the length of the sealer-cooler bars is approximately equal to the height from top to bottom panels of six or seven packages. Therefore, each carton will go through a plurality of sealing and cooling stations. The plurality of steps of both heating and cooling is necessitated by several factors. First of all, for rapid continuous filling no one carton or filled package can be kept in the same position for any appreciable amount of time. The motion althoughintermittent must be such as to move the cartons or packages forward steadily. Next, the packages should not have pressure applied during the forward motion if the pressure surface and the flaps being sealed are to move relatively to each other. Such relative motion produces a scufiing of the abutting carton flap surface as well as a dragging effect which tends to distort the carton shell so that the finished package is not squared. Last of all, the application of suificient heat and pressure to seal in one step results in a degradation of the thermoplastic material as well as the finish on the outside surface of the package. With the heat and pressure required for sealing applied in interrupted predetermined periods, the required melting and distribution of the thermoplastic adhesive is obtained without detrimental side effects to the carton.

Since the forward movement of the cartons through units B and C depends upon the drive means of unit A, the flow of cartons will halt if the drive means fail. If the time of failure is during a sealing step and if the pressure is not released, the cartons will scorch. To obviate scorching during failure of unit A, the sealer-cooler bars can be released by manually tripping the trigger. Scorching due to failure of the filling machine can also be avoided by using an electric timing device to motivate the solenoid actuated air valve. An electric timer is especially suitable if the sealing unit is to be used independent of any filling machine.

In the modification depicted in FIGURES 12 through 14, a heatsealing attachment, unit C, is suspended from the filling machine, unit A, by means of a connecting flange 210. Numerals 200-203, 208 and 209, correspond to numerals 100-103, 108, and 109 employed in FIG- URES 1-11. Included in this group are flap splitter 200, upper sealing blade 201, lower sealing blade 202, top folder 203, and lower flap closing plows 208 and 209. The unit shown in FIGURE 12 is basically constructed of two C-

plate end members

220, 221, a connecting bar 222 (shown in FIGURE 13) attached between their lower remote ends, and a tapered tubular support member 223 mounted on connecting flange 210 and to which

members

220, 221 are welded or otherwise attached. Surrounding these basic members are upper cover 224, outer side covers 225, 226, inner side cover 227, and lower cover 228. Projecting inwardly of the covers are the lower 231 and the side 232 sealing unit guide bars.

Lower sealer-cooler bar 235 and its connecting linkage is shown in FIGURE 13. The position of the bar is changed by a transfer of movement from solenoid actuated air motor 241 by means of the piston rod 242. The end of the cylinder 240 denoted as Y is connected to lower pivot block 250 which is secured to frame plate 251. In turn the frame plate 251 is immovably attached to connecting bar 222 and frame 223. The piston rod 242 is attached by a connecting pin 243 to actuating lever 244 which is connected to side pillow block 245 by connecting pin 246 and to upper pillow block 247 by connecting pin 248 on the sealing end of bar 235. Similarly, on the cooling end of the bar 235, toggle link 249 is connected to a side pillow block 255 by connecting pin 252 and to top pillow block 253 by connecting pin 254. The side pillow blocks 245 and 255 are attached to the C-

plate members

220, 221, respectively, and the top pillow blocks 247 and 253 to the underside of sealer-cooler. bar 235. The water for the cooling portion of bar 235 enters and leaves through inlet and outlet tubes 236, 237. correspondingly, heater lead wires 238, 239 lead to the sealing portion of the bar.

FIGURE 14 shows the upper sealer-cooler bar 260 with the cover plate 261 removed. Since, except for a thermostat, the upper and lower'sealer-cooler bars are essentially the same in structure, only the upper sealercooler bar will be described in detail. The bar consists essentially of a piece of metal 262 which has been machined out to provide a cavity for the heater 263 and cooling tube 264. A cover plate 261 which has a thermostat 265 attached fits over the top of the machined piece 262. Inlet and

outlet tubes

266, 267 project through the cover plate as do the

heater lead wires

268, 269. In operation the thermostat 265 controls the heater temperature in both the upper and the lower sealer-cooler bars.

As in the previously described embodiment, the cartons after being filled advance and undergo a series of foldings so that upper side flaps 1 and 3 and

lower side flaps

9 and 11 are folded about the upper and lower sealing blades, respectively. As the cartons reach the heatsealing unit, they are moved forward in abutting relationship supported on lower sealing unit guide bars 231.

Similar to the previous embodiment, the yoke connected to the drive bar contacts a trigger 270 when it moves back and forth. This motivates the solenoid actuated double acting air piston located in cylinder 240. When the yoke is moving forward, the contact with the trigger 270 sends an impulse through a relay, and conduit to an air valve, all of which are remotely located inside of tubular support member 223, and function in the same manner as in unit B. The solenoid in the air valve is then actuated so that air enters from the air inlet line 271 into end Y of the air motor 241 forcing the piston rod 242 to the left toward end X, retracting lower sealer-cooler bar 235. As the yoke begins its reverse stroke, it again strikes the actuating switch 270. This again triggers the solenoid so that air again enters from air inlet line 271, but into end X of the solenoid actuated air motor 241. The piston rod is forced toward end Y and the air in end Y of the motor exhausts. When the piston rod is at the Y end of the motor, the lower sealer-cooler bar has been raised and pressure is applied for sealing the cartons. Thus, as in unit B, pressure on the cartons is alternately applied and released. After the sealing step the carton is indexed forward to again go through another sealing step, or, at a further stage, it passes into the cooling portion of the unit which sets the activated adhesive to prevent rupture of the newly formed seal.

Unit C has the advantage of eliminating the alignment problems of unit B since unit C is automatically aligned with unit A when it is connected to and suspended from it. Further the design assures greater accessibility to the cartons in the unit. With the 0 frame design, there is an open side which enables the operator to reach and remove cartons that get jammed or out of line during operation. The use of one piston rather than two is retained since the actuating lever and toggle link in conjunction provide a more uniform rateof rise and descent for the lower sealer-cooler bar. The temperatures employed in the sealer-cooler bars in unit C are, as in unit B, dependent upon the residence time of the cartons in the unit.

The present invention may be, with minor modifications, employed with other filling machines than the one exemplified. The principles of intermittent pressure and indexing steps while advancing along heating and cooling elements give finished packages with a squared shape, scuff free surface and good seal in a rapid continuous operation. The temperature of the heating and cooling portions of the sealer-cooler bars may be varied to accommodate different operating speeds of the filling ma.- chine. A variety of thermoplastic materials may be employed on the flap surfaces for purposes of adhering the flaps in abutting relationship. If only a minimum amount of sealing pressure is necessary, due to the particular adhesive employed, it is obvious that the pressure absorbing surfaces may be eliminated. The packages sealed employing the method and apparatus of the present inventiondo not possess the inherent disadvantages found in the locked carton.

We claim: 7

1. Apparatus for continuously sealing, in a straight line operation, cartons having at each end pairs of opposed adhesive coated closure flaps comprising in combination a spaced pair of elongated sealing members, means for heating said members, means for intermittently conveying said cartons in a plurality of steps between said sealing members lengthwise thereof, means for folding said pairs of flaps into overlapping relationship between said sealing members, means for intermittently causing relative displacement of each of said pair of sealing members toward and into contact with the respective pair of adjacent overlapped flaps simultaneously to apply heat and pressure thereto, and nieans interconnecting the conveying means and the sealing member displacement means to cause alternate operation of said two last-mentioned means so as to apply heat-and pressure to said pairs of closure flaps a plurality of times as the cartons are conveyed between said sealing members;

2. Apparatus for continuously sealing, in a straight line operation, cartons having at each end pairs of opposed adhesive coated closure flaps comprising in combination a spaced pair of elongated sealing members, means for heating said members, a spaced pair of elongated pressure absorbing surfaces interposed between and adjacent said members, means for intermittently conveying cartons in a plurality of steps between the pressure absorbing surfaces lengthwise thereof, means for folding said pairs of flaps into overlapping relationship between the adjacent of each of said pair of surfaces and said sealing members, means for intermittently causing relative displacement of said sealing members toward the adjacent pressure absorbing surfaces and into contact with the respective pair of adjacent overlapped flaps simultaneously to apply heat and pressure to said overlapped flaps, and means interconnecting the conveying means and the sealing member displacement means to cause alternate operation of said two last-mentioned means so as to apply heat and pressure to said pairs of closure flaps a plurality of times as the cartons are conveyed between said sealing members.

References Cited in the file of this patent UNITED STATES PATENTS 1,531,009 Korth Mar. 24, 192 5 1,883,229 Bent Oct. 18, 1932 2,218,585 Merkle Oct. 22, 1940 2,263,691 Enkur Nov. 25, 1941 2,551,527 Cartwright May 1, 1951 2,764,862 Rado Oct. 2, 1956 2,978,007 Jensen Apr. 4, 1961 3,010,267 Richardson et al. Nov. 28, 1961

Claims

1. APPARATUS FOR CONTINUOUSLY SEALING, IN A STRAIGHT LINE OPERATION, CARTONS HAVING AT EACH END PAIRS OF OPPOSED ADHESIVE COATED CLOSURE FLAPS COMPRISING IN COMBINATION A SPACED PAIR OF ELONGATED SEALING MEMBERS, MEANS FOR HEATING SAID MEMBERS, MEANS FOR INTERMITTENTLY CONVEYING SAID CARTONS IN A PLURALITY OF STEPS BETWEEN SAID SEALING MEMBERS LENGTHWISE THEREOF, MEANS FOR FOLDING SAID PAIRS OF FLAPS INTO OVERLAPPING RELATIONSHIP BETWEEN SAID SEALING MEMBERS, MEANS FOR INTERMITTENTLY CAUSING RELATIVE DISPLACEMENT OF EACH OF SAID PAIR OF SEALING MEMBERS TOWARD AND INTO CONTACT WITH THE RESPECTIVE PAIR OF ADJACENT OVERLAPPED FLAPS SIMULTANEOUSLY TO APPLY HEAT AND PRESSURE THERETO, AND MEANS INTERCONNECTING THE CONVEYING MEANS AND THE SEALING MEMBER DISPLACEMENT MEANS TO CAUSE ALTERNATE OPERATION OF SAID TWO LAST-MENTIONED MEANS SO AS TO APPLY HEAT AND PRESSURE TO SAID PAIRS OF CLOSURE FLAPS A PLURALITY OF TIMES AS THE CARTONS ARE CONVEYED BETWEEN SAID SEALING MEMBERS.