US 3664296 A
This invention relates to an apparatus for applying sealant to the edge face of a container blank of the type used to package liquids such as milk. The principle of the invention is an applicator wheel that enters into a sealant pot and picks up a ribbon of sealant as its rotates. The edge of the container blank to be sealed is caused to engage with and pick up the ribbon of sealant on the wheel. A feature of the invention is the design of the sealant pocket of the applicator wheel which is adapted to place sealant on the edge face only of the container blank.
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Description (OCR text may contain errors)
United States Patent Stamp et a1.
1151 3,664,296 14 1 May 23, 1972  SEALING COMPOUND APPLICATOR  lnventors: George Frederick Stamp; Kenneth Allan Walker, both of London, Ontario, Canada Somervllle Industries Llinited, London, Ontario, Canada 22 Filed: Sept. 21, 1970 21 App1.No.: 74,063
 Foreign Application Priority Data Aug. 25, 1970 Canada ..091,7o0
 11.5. C1 ..ll8/246, 118/252 1316,1105 1/191) Replogle ..l18/252 FOREIGN PATENTS OR APPLICATIONS 74,283 12/1944 Czechoslovakia ..1 18/252 Primary Examiner-Henry S. Jaudon AttorneyFetheistonhaugh & Co.
57 ABSTRACT This invention relates to an apparatus for applying sealant to the edge face of a container blank of the'type used to package liquids such as milk. The principle of the invention is an applicator wheel that enters into a sealant pot and picks up a ribbon of sealant as its rotates. The edge of the container blank to be sealed is caused to engage with and pick up the ribbon of sealant on the wheel. A feature of the invention is the design of the sealant pocket of the applicator wheel which is adapted to place sealant on the edge face only ofthe container blank.
3 Clains, 6 Drawing Figures AIENTEDIAY23 I972 3,664.296
SHEET 2 OF 2 Y l 2O 23 22 18 FIG. 2
IN VIL'NI ()R. GEORGE F. STAMP KENNETH A. WALKER yfladk /yg ATTORNEYS SEALING COMPOUND APPLICATOR This invention relates to apparatus for applying a sealant to an edge face of a carton blankand it has particular application to the manufacture of plastic coated paper board containers used for packaging of liquids such as milk and fruit juices.
A widely used container for such purposes has a gabled top and a squarecross section body with an overlapping side seam that extends down into a flat bottom. The blank for the container is formed from a plastic sealant coated paper board and it is liquid proof but the edge faces of the blank where the blank has been cut are not sealed with plastic composition. In many types of construction, the raw unsealed edge face of an inner lap of the side seam is exposed to the liquid contents of the container in use and liquid from the container migrates into the paper board between the plastic sealed surfaces at the side seam. This can cause failure of the container and means for sealing the raw edge face of the container that comes into contact with the liquid have been adopted. One such means is disclosed in Canadian Pat. No. 790,997 which issued on July 30, 1968. According to the invention disclosed in that patent, the raw edge face of the blank is coated with a sealant material while the blanks are in stacked formation. The solution to the problem described in Pat. 790,964 is not satisfactory from an operational point of view as desired because there is a tendency for sealant applied to the edge faces of the stacked cartons to extend between the carton blanks and cause the blanks to stick together or block. Moreover and apart from blocking any smearing of the face of the carton blank is undesirable because it may prevent a perfect seal in the construction of the carton.
It is therefore an object of this invention to devise an improved manner for sealing the raw edge face of a container edge in a manner that will avoid blocking and smearing of the front or back face of the container blank.
Generally speaking, apparatus for applying a sealant to an edge face of a carton blank according to this invention comprises a conveyor, a container for sealant at a side edge of said conveyor, an applicator wheel rotatably mounted with its lower portion extending in said container for sealant to engage with sealant in use, said applicator wheel being formed with an open sealant pocket facing said conveyor that extends 360 around said applicator wheel, wiper means above the sealant level of said container for sealant in wiping engagement with said applicator wheel to remove sealant from said wheel except at said open sealant pocket as said applicator wheel rotates in use, means for projecting the side edge face of an overhanging side margin of a container blank on said conveyor into said open sealant pocket, and means for rotating said applicator wheel as said conveyor conveys carton blanks to apply a continuous ribbon of sealant from said open sealant pocket to the side edge face of a container blank carried by said conveyor. The invention will be clearly understood after reference to the following detailed specification read in conjunction with the drawings.
In the drawings:
FIG. 1 is a perspective illustration of a portion of the horizontal conveyor of a machine for folding and side seaming containers with side edge face sealing device according to this invention;
FIG. 2 is a cross sectional view of the machine;
FIG. 3 is a view illustrating the design of the wiper blade;
FIG. 4 is a view of one type of blank with which the invention is concerned; and
FIG. 5 is a view of the blank in the tubular flat foldable form.
FIG. 6 is a cross sectional view of the blank edge with sealent applied.
FIGS. 4 and 5 illustrate a type of container blank with which this invention is useful. The blank has four side walls 10, 12, 14 and 16 and panels above them from which a top is formed and panels below them from which a bottom is formed. The blank is customarily formed into a tubular formation and shipped in a flat folded condition to the user who sets the carton up by folding the side, bottom and top walls into position as he fills the container with liquid. In the formation of the tubular form, the sealing flap 18 is heat sealed to the inside marginal surface area of the wall panel 16 and to the top and bottom panels that connect with the wallpanel 16. This is done on 'a machine known as a flame sealer, which melts the plastic coating on the paper board at the areas to be sealed and contacts the surfaces so that as it cools a seal between the heat activated surfaces is achieved.
-As previously indicated, the edge face of the sealing flap 18 is not sealed as a result of the cutting of the blank. It will be apparent that unless sealed, liquid on the inside of a setup container'will wick into the absorbent paper of the container at this edge. This invention is concerned with the sealing of the edge face of the flap 18 in a manner that will not cause blocking or sticking together of the blanks and in a manner that will not smear the surfaces of the blank with sealant.
A blank as illustrated in FIG. 4 is folded and sealed to form a tubular structure as illustrated in FIG. 5 on a machine known as a flame sealer. This machine includes a' horizontal conveyor which registers the blank, folds it, heats the surfaces to be sealed to activate the sealant and presses the activated surfaces to seal the juxtaposed surfaces of the flap l8 and the panel 16. The apparatus of this invention is mounted at the side of the horizontal conveyor of the flame sealer and is capable of applying a ribbon of sealant to the side edge face of the flap 18 as it is transported by the conveyor.
FIG. 1 shows the conveyor of a conventional flame sealer for sealing the flaps 18 to the inside surface of wall 16 of a container blank. It consists of two belts 20 and 22 supported according to well known and general practise by supports such as the support 23. The carton blanks are automatically fed on to the conveyor in close spaced apart relation with their flaps 18 overhanging one side edge of the conveyor. The opposite side edge of the blank overhangs the opposite side edge of the conveyor and as the blanks are conveyed along the conveyor in the direction indicated by the arrow, they are engaged by co-operating rollers 24 and 26 of the register section-which extend generally transversely of the conveyor but are biased in the direction of travel of the conveyor. Rollers 24 and 26 are driven by means of drive belt 28 to pull the carton blanks laterally of the conveyor and locate a side edge thereof against the locating backstop 30. Rollers 24 and 26 and their operation to locate blanks against the backstop are well known and not per se part of this invention.
Sealant 40 to be applied to the edge face of the flap 18 is maintained in liquid form within the pot 42 by means of electric heater 44. A blend of resin and wax such as a mixture of a thermoplastic polyethylene with wax having a melting point of about 230 F. has been found satisfactory as a sealant. Other blends of sealant are possible for example, polypropylene or polyvinylchloride could be blended with wax. An applicator wheel 46 is rotatably mounted between the sides of the container 42 and drivenby means of belt 48 from the driven shaft of the flame sealer at the head of the register section.
The applicator wheel is made of brass and formed with a continuous open pocket 50 which, in the embodiment illustrated, is defined by two walls that converge at an angle greater than It will be apparent that as the applicator wheel 46 rotates and its lower portion enters into the sealant 40, sealant will adhere to its surface as it emerges from the sealant bath. A wiper plate of stainless steel 52 extends around the outer annulus of the applicator wheel that enters the sealant bath and wipes the sealant from the wheel at all places except the pocket 50. In this respect, it will be noted that the wiper plate 52 is formed with a cut-away corner as at 54 at the pocket 50 to permit a continuous ribbon sealant to remain in the pocket of the applicator wheel. This ribbon of sealant is carried upwardly by the wheel and subsequently applied to the side edge face of the flap 18 as will be explained. Wiper plate 52 is bolted to the sealant pot 42 by bolts 53 which pass through the slots 55 in one end of the wiper plate.
As explained above, one side edge of the blanks is positively located against the backstop 30 and the flap 18 of the blank overhangs the opposite side edge of the conveyor. As the blanks arecarried towards the rotating applicator wheel 46 by the conveyor they are deflected downwardly as they encounter the deflecting arms 56. Arms 56 deflect the flap 18 downwardly so that the edge face of the side edge thereof enters the pocket 50 and the ribbon of sealant carried by the pocket is transferred to the edge face of the container.
Pocket 50 is formed by the intersection of a horizontal wall and a vertically inclined wall that meet at an angle of more than 90. The walls are adapted to apply sealant to the end face only of the deflected flap 18. There is little or no scrubbing of a side face of the flap and therefore no application of sealant to a side face.
The sealant to be applied to the edge face of the container blank is contained in the pocket and it is desired that the container should engage the wheel only at the pocket. If the pocket were formed with a vertical wall instead of a vertically inclined one the edge of the container would rub against the vertical wall as it approached and as it moved away from the pocket that contains the ribbon of sealant. While the surface of this wall beyond the pocket is scraped substantially clean by scraper 52 there is sufficient sealant on it to mark the side face of the container. The wall is therefore, inclined from the vertical away from the conveyor to provide clearance for the container as it approaches the pocket. An angle over about 1 will provide the necessary clearance but it is desirable not to make the inclination larger than necessary for clearance in order to keep the pocket angle small so that the pocket forms a tight sealant receiver. A wall vertically inclined about 5 from the vertical in combination with a horizontally extending wall provides good clearance and a tight sealant pocket. Thus, the path of the edge face of a container into the pocket in use is unobstructed by the vertical wall of the wheel.
As each container is carried beyond the wheel 46, its flap 18 is carried beyond the arms 56 and it reasserts itself to assume its flat position and proceeds to the melting and contacting operations to form a tube with a sealed side seam.
Container blanks move along the conveyor at a speed of about 1,000 feet per minute and the speed of the applicator wheel 46 is such that the lineal speed of the pocket that engages the edge face of the blank is the same as the conveyor speed, i.ei 1,000 feet per minute. Thus, the sealant carried in the pocket is carried forward at the same speed as the speed of the conveyor and substantially all applied to the container.
The conveyor speed must be fast enough to permit the flap 18 to be folded and sealed against wall 16 as shown in FIG. 5 before the heat activated surface sealant sets. Presently popular paper board coatings melt at about 230 F. and with these the conveyor speed must be in the order of 1,000 feet per minute to achieve the seam seal before setting. Speeds faster and in the order of 1,500 to 2,000 feet per minute are possible. Speeds of less than 500 feet per minute are too slow because the activated sealant would reset before the seam was secured.
In any event the lineal speed of the pocket must be about the same as the lineal speed of the conveyor.
The edge sealant in tank 42 must be one which will set before the tubular container is stacked in the form of FIG. 5. Otherwise the containers would block and be difficult toopen. It has been found that a thermo-plastic sealant of polyethylene and wax having a melting point of about 230 F. works well at a conveyor speed of about 1,000 feet per minute. Higher melting points would work. However, if one were to use a very low melting point sealant in the tank 42, it would be plastic at the time of folding and would cause blocking.
The side edges of container blanks are deflected as ex plained above as they approach the sealant pocket so that they enter into the open sealant pocket to pick up a coating of sealant on their edge face as they travel along the horizontal extent of a conveyor in a standard flame sealer. Coating is achieved without blocking and without smearing the side faces of the carton.
The embodiments of the invention in WhlCl'l an exclusive property or privilege is claimed are defined as follows:
1. Apparatus for applying a sealant to an edge face of a container blank comprising a conveyor, a container for sealant at the side edge of said conveyor, an applicator wheel rotatably mounted with its lower portion in said container to engage with sealant in use,'said applicator wheel being formed with open sealant pocket facing said conveyor that extends 360 of said applicator wheel, wiper means above the sealant level of said container in wiping engagement with said applicator wheel to remove sealant from said applicator wheel except at the said pocket as said applicator wheel rotates in use, said sealant pocket having a width to admit the side edge face of a container blank, means for projecting the side edge face of an overhanging side margin of a container blank on said conveyor downwardly into said open sealant pocket, means for rotating said applicator wheel as said conveyor conveys container blanks to apply a continuous ribbon of sealant from said sealant pocket to the side edge face of a container blank carried by said conveyor.
2. Apparatus for applying a sealant to an edge face of a container blank as claimed in claim 1, in which said open sealant pocket is defined by two walls, one of said walls is vertically inclined away from said conveyor.
3. Apparatus for applying a sealant to an edge face of a container blank as claimed in claim 1, in which said wall that is vertically inclined is vertically inclined about 5 from the vertical.
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