US3524425A - Apparatus for waxing cartons - Google Patents

Description

United States Patent Inventors Bayard I. Barnes Oakland, California; James Aubrey Sweet, Orinda, California;

Kramer L. Barnes, Oakland, California APPARATUS FOR WAXING CARTONS 1 Claim, 2 Drawing Figs.

US. Cl 118/47, 118/69,118/101,118/106,117/64,11711192, 1 17/158 Int. Cl B05c 11/00 Field of Search 1 17/64,

119.2,158, 119.4, 37, 115; 118/69; 1l7/64C, 38, 46FC;1l8/100,10l,106,110; 117/46 Primary Examiner- Alfred L. Leavitt Assistant Examiner- Janyce A. Bell Attorney Robert P. Auber and Leonard R. Kohan ABSTRACT: A method and apparatus for coating sheet material such as paperboard cartons with a coating of wax. The method and apparatus provides for applying a high gloss finish to the wax coating by means of heating the coating and subsequently cooling the coating by means of a water bath or by means of a cooled casting belt. During the course of heating the coated surface, the opposite surface of the sheet is simultaneously cooled to enhance the high gloss finish imparted to the carton. The carton may be pressed onto the lower run of a cooled casting belt so to be delivered from the casting belt in a face-up position, the better to inspect the high gloss finish of each carton as it is removed from the casting belt.

APPARATUS FOR WAXING CARTONS This application is a continuation of our co-pending application, Serial No. 286,974, filed June 11, 1963, now abandoned.

This invention relates to an improvement in method and apparatus for coating sheets and deals particularly with an apparatus capable of applying a coating of wax or similar materialto the surface of a carton blank in a predetermined pattern, and also including means for applying a high gloss finish to the wax coating when desired.

During recent years, the production of cartons having an extremely high gloss surface has greatly increased. The number of coated cartons produced for the trade has also greatly increased. One of the difficulties which is commonly experienced with cartons of this type lies in the fact that they do not lend themselves to sealing by inexpensive adhesives without special treatment. For example, a carton which has been coated with a high gloss wax usually must either be sealed by the use of a hot melt adhesive which penetrates the coating, or else a portion of the wax must be removed or driven into the paperboard to the extent necessary to permit the adhesive to adhere. Thus the purchaser of cartons of this type is usually penalized not only by the increased cost of the cartons due to the application of the mirrorlike finish, but also by the problem of properly gluing the containers once they are obtained.

in our previous application for patent, Serial No. 138,657 filed September 18, 1961 now abandoned for Waxing Apparatus, we described a machine which differed from conventional waxing devices by applying the coating only over a predetermined area of the carton. In other words, with this apparatus, it is possible to omit the coating from the glue flap, and from selected portions of the sealing flaps, so as to permit the carton to be adhered in tubular form, and closed and sealed with adhesive of conventional type. However, while the structure disclosed imparts a glossy surface to the wax, it does not impart the extremely high gloss of certain other coating processes.

A feature of the present invention resides in the provision of a method and apparatus for applying a coating either to one or both surfaces of a sheet and to selective areas thereof, and which is capable of applying an intense heat to one surface of the sheet while the other surface is being cooled. As a result, it

is possible to produce a glossy surface on the sheets without heating the entire blank, thereby localizing the extreme heat to the area to be treated.

A further feature of the present invention resides in the provision of an apparatus which is adaptable for use in the treatment of carton blanks and the like either to reheat the upper exposed surfaces ofthe sheets and to then cool the surface to provide a glossy surface, or else to reheat the upper exposed surface and then to impinge the coated surface to a highly polished belt or drum to produce a surface of much higher gloss. As a result, the same apparatus may be used to produce a coated area on the cartons, leaving the areas which are to be adhered together uncoated; and then to treat the carton to improve the gloss, or else to cast the surface on the same cartons or blanks to produce a mirrorlike finish thereupon.

It is an object of the present invention to provide an apparatus which includes a solid belt conveyor to which the sheets are delivered, and which is cooled by suitable means such as by immersing the solid conveyor belt in a cooling tank during its travel about its endless path. As a result, this conveyor belt cools the under surface of the cartons at the same time the upper surfaces of the sheets or cartons are being subjected to a heat sufficient to at least partially melt the upper coated surface at a time just prior to pressing the individual cartons or sheets against a highly polished surface. With this arrangement, the cartons will release readily from the highly polished casting surface as the heat from the remelted coating enters the blank.

An added feature of the present invention resides in the provision of an apparatus of the type described which may include a belt of stainless steel or the like to act as the casting surface and which includes means for impinging the cartons against the belt on the under surface thereof as it travels along a generally horizontal path. The carton blanks are thus carried with the coated surface uppermost. This arrangement eliminates the necessity of reinverting the cartons as they leave the belt, thus simplifying inspection and packing.

In the past where flexible stainless steel, highly polished belts have been used for imparting a mirrorlike finish to the outer exposed surfaces of the cartons, it has been common practice to apply the coated surface to the upper side of the belt, and then to remove the cartons from the belt while in inverted position. As a result, it is necessary for the person packaging the coated cartons to turn the cartons over for inspection. With the present arrangement, the coated containers are delivered to a conveyor belt while in fanned out overlapping relation so that the packer is immediately aware if the cartons are not being coated properly, and to make sure that the proper areas of the blanks, and only the proper areas are being coated.

It is an important feature of this invention that the present process produces a mirrorlike finish on one board surface without destroying the coating on the opposite surface. In the past, the reheating of the blank has usually resulted in having the heat penetrate through the paperboard at least to some extent due to the intensity of the heating element required. As a result, when the reheated blank is impinged upon the casting surface, the impinging roll will either pick off a portion of the wax, or else drive it into the board. By cooling the back of the blank while the intense heat is directed to the opposite surface, the coating on the back surface remains solid, and the picking or driving of the coating on the back surface does not take place.

These and other objects and novel features of the present invention will be more clearly and fully set forth in the following specification and claims.

in the drawings forming a part of the specification:

FIGURE 1 is a diagrammatic side view, partly in section, showing the inlet end of the coating apparatus, the view being partially in section.

FIGURE 2 is a view similar to FIGURE 1 and showing the outlet end of the same apparatus.

In view of the fact that the apparatus used for coating carton blanks and other sheets, as well as the drive apparatus for such structures is well known in the art, the figures do not go into detail in this respect. However, the drawings do describe the apparatus in sufficient detail so that one skilled in the art could produce an apparatus of the type described.

During the following description and claims, the applicants have in some instances referred to the members being coated as sheets, and in other instances have referred to them as carton blanks. lt should be recognized that while the present invention is most commonly used for the coating of carton blanks, the method is similarly equally adaptable to sheets of rectangular or other shape, and accordingly the two terms have been used interchangeably. It should also be mentioned that in some instances the applicant has referred to the coated side of the carton or sheet where, in actual practice, both sides of the sheet may be coated. Accordingly, the term is not meant to exclude cartons which are coated on more than one side, but merely to describe a coated surface which would normally form the outer or exposed surface of the carton, and in any event to describe the surface toward which the heating elements designed to reheat the coating to at least a partially molten state is directed.

The coating apparatus which is illustrated in the drawing includes a first section which is indicated in general by the letter A, and a second section which is indicated in general by the letter B. The first section is designed to apply a coating to the sheets, either on one or both surfaces thereof. When the mirrorlike finish is not required, the coating is reheated into at least a partially molten state, and then immediately cooled if this is the extent of the treatment required, the sheets may be removed after passing through section A of the apparatus which is generally similar to the apparatus illustrated in our previous patent application referred to above. Section B of the apparatus comprises the means for imparting the mirrorlike finish to the coating when such is desired.

Section A includes a feed table of conventional type which supports the series of sheets or carton blanks C which are to be coated. These sheets are fed one at a time by suitable feed wheels 11 and 12 to a conveyor 13 which moves the sheets in spaced timed relation. The conveyor 13 directs the sheets one at a time between an upper pattern coating roll 14 and a lower pattern coating roll 15. These rolls 14 and 15 are provided with printing blankets or similar means which engage opposite surfaces of the sheets and which applies a predetermined pattern of coating thereto. The coating is applied to the surfaces of the rollers 14, 15 from supply troughs or the like 16, 17 by means of knurled rollers 19, 20 or other suitable means, The arrangement is designed to provide a coating of a predetermined thickness either on the upper surfaces of the sheets, or on both surfaces thereof.

A series of parallel belts 21 are guided in endless paths by a pair of horizontally spaced guide rollers 22 and 23, the belt passing over intermediate space supporting rollers such as 24. A tank 25 containing water or other cooling medium is located beneath the conveyor belts 21, and portions of the belts are preferably guided through the water by means of idler pulleys 26 and 27. Means such as doctor blades 29 may engage the surfaces of the belts to remove the excess water therefrom.

A plurality of burners such as 30 are supported over the conveyor belts 21 extending transversely of the tank 25. These burners 30 are designed to direct intense heat toward the sheets carried over the surface of the belts 21. The burners or heaters 31 are of the necessary intensity to heat the exposed surface of the coating on the sheets C to a temperature in which the coating is softened or partially melted. This action has a tendency to smooth out the surface of the coating and to remove the small lines which often form in the coating as the coating sets. Immediately after the sheets have been reheated by the heater 30, the sheet surfaces are cooled by a continuous shower of water indicated at 31, or the cartons may be cooled by passing them through a cooling tank of the type conventional with devices of this type. After leaving the conveyor belts 21, the sheets pass between a pair of ringer rolls 32 and 33 where excessive moisture is removed. Means are provided, not illustrated in the drawings, for moving these rollers apart if the heating members 30 and water shower means 31 are not being used. After passing between the ringer rollers 32 and 33, the sheets are directed on to a conveyor section 34 supported on a generally horizontal plane by suitable supporting rollers 35 and 36. As will be well understood by one skilled in the art, the conveyor 34 may operate at a varying speed dependent upon the use to which the apparatus is put. 1f the sheets are not to undergo further treatment, the conveyor belts 34 are usually driven at a speed considerably less than that of the belts 21 so that the sheets will fan out in overlapped relation to simplify their removal from the conveyor for packing. While the frame of the applicants apparatus is only diagrammatically described, legs 37 are shown supporting the tank 25 and conveyor belts 21 and associated mechanism, and a second pair of legs 39 are diagrammatically illustrated as supporting the conveyor 34. A stacker board 40 is supported by one of the leg sections 39 at the discharge end of the conveyor 34 for the convenience of the packer and inspector. The sheets will drop on to the stacker board 40 if not previously picked up, the stack may be squared up in a conventional manner and placed in a suitable shipping container. As previously indicated, this comprises the section indicated by the letter A and which is quite similar to the structure shown in our previous application for patent.

A conveyor 41 forms the connecting link between the sections A and B. The conveyor 41 is supported in a suitable frame between a pair of rollers 42 and 43, and when in the horizontal position indicated in full lines in the drawings, the

conveyor 41 forms merely a continuation of the conveyor 34.

However, when the section B of the apparatus is not to be in use, the conveyor 41 may be swung into the position shown in 5 dotted outline in FIGURE 1 of the drawings. When in this position, the inspector and stacker may readily remove the cartons as they near the stacker table 41, and package them at this point. When in lowered position, the conveyor 41 is supported by suitable leg sections 44. Section B of the apparatus includes a framework 45 which supports conveyor rollers 46 and 47 about which extend an endless solid belt conveyor 49. The belt conveyor 49 is also guided by an idle roller 50 supported within a tank 51. The tank 51 contains cooling water through which the belt passes, the excess water being removed by suitable doctor blades 52. The belt 49 is thus cooled and acts to cool the under surface of the sheets C as they pass along the conveyor 49. A series of heating elements 53 are arranged above the belt 49 near the discharge end of the conveyor to direct intense heat toward the upper exposed coating on the sheets C. Thus while the under surfaces of the sheets are held at a relatively low temperature by the cooled belt, the heaters act to partially melt the coating on the upper surface and at least heat it to a plastic state. With reference now to FIGURE 2 of the drawings, the section B also includes a pair of rollers 54 and 55 which are of sufficiently large diameter to support a flexible stainless steel belt 56 or other similar type of belt having a highly polished surface. The rollers are supported by a framework 57 which also supports an impinging roll 59 located beneath the roller 54. The sheets or carton blanks C are fed from the conveyor 49 between the impinging roll 59 and the surface of the belt 56, and the force is sufficient to adhere the sheets to the surface of the belt as the belt travels along its path in the direction of the arrow 60. A cooling water tank 61 is provided beneath the upper reach of the middle belt 56 to hold the belt temperature relatively low. An insulation baffle 62 is provided between the heaters 53 and the roller 54 to prevent the belt 56 from being reheated by the heaters.

A rubber roller 63 is positioned between the roller 55 at the discharge end of the metal belt 56 to control the carton upon release from the belt. An air knife 64 directs a blast of air between the sheets and the belt 56 as they are released from the belt, the cartons being directed on to an outlet conveyor 65 supported by rollers 66 and 67. The conveyor 65 then deposits the sheets one at a time on to a conveyor 69 which is supported by rollers 70 and 71 on a generally horizontal plane and which travels at a slower speed so that the sheets or cartons are shingled into overlapping relation as they approach the second stacking table 72.

It is within the scope of the present invention to employ a highly polished casting drum in place of the belt 56, and equally good results may be obtained thereby. The advantage of impinging the upper surfaces of the cartons upon the lower reach of the belt converyor is manifold. 1n the first place, this arrangement allows the cartons being discharged from the belt 56 to be upright rather than inverted thus permitting a visual inspection of the sheets at the completion of the casting operation. Furthermore, this arrangement permits the heaters or burners to flow the surface wax on the upper surface of the carton while the under surfaces thereof are being cooled by water carried by the belt 49. Furthermore, this arrangement permits the heat from the surface of the coating to enter the cartons as they travel along the belt 56, allowing a colder impingement temperature combined with easy release. Releasing the sheets from the under surface of the belt is naturally easier than releasing them from the upper surface thereof, and there is a definite advantage in maintaining the under sides of the sheets cool while the upper surface is being heated due to the fact that the tendency for the temperature in the cartons to equalize more quickly carries the heat from the upper coated surface.

The operation of the apparatus and the method of coating the sheets is believed generally obvious from the foregoing description. The structure is flexible in that the section A of the apparatus may be used to apply a pattern of wax to the sheets or carton blanks, reheat the coating to flow the surface of the coating and immediately subjecting the coated surface to water thereby producing sheets possessing a sufficiently glossy surface for most purposes. However, if the cartons are to be provided with a mirrorlike finish, the section B of the apparatus is set into operation, the conveyor 41 being swung down to receive cartons from the conveyor 34. In this case, the burners 30 and water shower 31 are usually turned off, and the speed of the conveyor 34 is increased to approximate the speed of the conveyors 21 and 41, thereby maintaining the cartons in spaced relation on the conveyors. By heating the upper exposed surfaces of the sheets with the burners or heaters 53, and impinging the heated surface against the belt 56 or against the surface of the highly polished drum, the cartons will receive a very high degree of gloss.

In accordance with the patent statutes, the principles of construction and operation of this improvement in Method an Apparatus for Coating Sheets" have been described, and

while an endeavor has been made to set forth the best embodiment thereof, it should be understood that changes may be made within the scope of the following claim without departing from the spirit of the invention.

We claim:

1. In an apparatus having means for applying a hot melt coating to carton blanks and having means for heating the coating prior to imparting a high gloss finish to the coating, the improvement which comprises an endless belt having a highly polished casting surface for receiving the blanks from said heating means, a pair of spaced rollers for supporting said belt, impinging means cooperating with one of the spaced rollers for pressing the coated surfaces of the carton blanks onto the lower run of said endless belt so that the carton blanks adhere without additional support means to the underside of the lower run of said belt, means adjacent the other spaced roller for removing the carton blanks from the endless belt, and means for cooling the upper run of said endless belt.

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