US2368130A - Apparatus for coating containers - Google Patents

Description

aearcn WOO" Jan. 30, 1945. v. A. FOX

APPARATUS FOR comma cormmsas Filed Dec. 19, 1941 4 Sheets-Sheet l .frzverar Ernie a. fix

Jan. 30, 1945. v. A. FOX

APPARATUS FOR COATING CONTAINERS Filed Dec. 19, 1941 4 Sheets-Sheet 2 fnvent ar .VG-TVZL'G Q. fax if Z Jan. 30, 1945. 2,368,130

V. A. FOX

APPARATUS FOR COATING CONTAINERS Filed D60. 19, 1941 4 She'ets-Sheet 3 mwbg 4 Sheets-Sheet 4 V. A. FOX

APPARATUS I'OR COATING CONTAINERS Filed D60. 19, 1941 Jan. 30, 1945.

Patented Jan. 30, 1945 OCGHJII "UUli UNITED STATES PATENT OFFICE APPARATUS FOR COATING CONTAINERS setts Application December 19, 1941, Serial No. 423,628

6 Claims.

This invention relates to the coating of containers and more particularly to an improved apparatus for coating containers having one closed end and one end with a relatively large opening therein.

Many methods and machines have been devised heretofore for the purpose of coating containers of various kinds by dipping, spraying, flooding, etc., but many of these are adaptable only for coating the exterior container surfaces, and others have failed to produce an unbroken and substantially uniform coating on both the inside and outside of the containers being processed because they required that these containers be firmly held by some sort of clamping device. The failure of the prior art methods and machines to produce a complete film of coating material over the container has retarded the development of inexpensive packages which are resistant to the action of moisture vapor, oil, or other materials.

I have devised an improved apparatus whereby a complete and uniform coating of the desired material can be applied to tubular containers, such as folding cartons adapted to be used for food products and the like. Many types of coating materials can be used, depending upon the type of product with which the containers are to be filled, but my invention is particularly adapted for use in connection with a thermoplastic material which imparts unusually high resistance to the passage of moisture vapor through containers coated therewith, and it will be described principally in connection with the use of such a coating material.

It is an object of my invention to provide an improved apparatus for applying a substantially uniform film of a coating material to the internal and external surfaces of a container, preferably a tubular container formed from a foldable blank, having one of its ends closed and the other open or formed with a relatively large opening therein. A further object is to provide apparatus of this type particularly adapted for use in connection with thermoplastic coating materials and which requires a minimum of floor space. Further objects, advantages and uses of my invention will be apparent from the following detailed description read in conjunction with the drawings, in which:

Fig. 1 shows somewhat schematically a longitudinal cross-section through one form of coating apparatus according to my invention.

Fig. 2 is an enlarged view illustrating in an exaggerated manner the way in which any air trapped within the containers during the coatin operation i prevented from interfering with the production of an unbroken film of coating material.

Fig. 3 shows a side view of one of my preferred forms of container supports and the manner in which a container rests thereon.

Fig. 4 is a partial cross-sectional view taken along line 4-4 of Fig. 1.

Fig. 5 is a cross-sectional view taken along line 5-5 of Fig. 4.

Fig. 6 is a top view of one of the container supports illustrated in Figs. 3 and 4.

Fig. 7 is a side view of the container support shown in Fig. 6, and

Fig. 8 is a longitudinal cross-section through a modified form of coating apparatus embodying my invention, which is similar to that shown in Fig. 1, but omits the pre-heating means.

In one of its broad aspects, my invention comprises introducing containers having one closed end and one end with a relatively large opening therein into a bath of coating material, rotating these containers within the bath from ap proximately horizontal position through an angle substantially greater than about a horizontal axis which is substantially perpendicular to the longitudinal axis of the containers, the direction of rotation being such that the open end of each of these containers passes through and beyond its downwardly facing position. It will be seen that this results in the trapping of a minimum of air against the closed end of the container and that, if any air is so trapped, it is caused to move from one side of the container to the other, thus allowing the coating material to come in contact with the entire interior surface thereof. My invention can best be understood in all of its details, however, by reference to the drawings which show forms of apparatus suitable for achieving this result including many other features.

Referring now to Figs. 1, 4 and 5, a pair of endless roller chains Mare caused to move generally upward in parallel paths from a pair of sprockets l I over a pair of sprockets l2 and then downward around the lower portions of a third pair of sprockets [3 which are located within a receptacle l4 adapted to hold a pool or bath of the desired coating material. The shaft I5, upon which sprockets iii are mounted, is located slightly below the liquid level I6 of the bath, so that chain III are caused to enter into the bath a substantial distance. It is desirable that chains It should enter the bath in substantially vertical position and this is achieved by causing these chains to roll along a pair of guides ll between sprockets l2 and sprockets l3. Chains l then pass upwardly preferably at an angle somewhat less than 90, but greater than 45, from the horizontal over a pair of guides l8 which have long substantially horizontal portions extending through the heating and cooling chambers to be described below. Chains I then pass over a pair of sprockets I9 which are driven by any suitable means (not shown) and then back to the lower portion of sprockets ll along a path defined by guides 20 and 2|.

Spaced along the chains are a number of container supporting devices which can best be seen in Figs. 4 and 5. Rigidly fixed to corresponding links in the chains H) are inwardly extending arms 22 having holes therethrough into which are inserted the upwardly extending portions of a U-shaped bar 23, these upwardly extending portions being held in a position perpendicular to the position of the corresponding links by means of nuts 24. One or more rods or spindles 25 are attached by welding or the like to the horizontal portion of each bar 23, and these also are perpendicular to the links of the chains ill with which they are associated. Each of the spindles 25 has its free end bent in substantially horizontal position and carries two rod-like members 26 extending laterally on either side thereof and bent upwardly at an acute angle as shown in Fig. 7. The ends of the members 26 are curved so as to provide rounded surfaces for supporting the containers to be coated, and the forward ends of each of these members, that is, the ends extending in the direction of movement, are somewhat more elevated than the following ends, as shown in Figs. 3 and 7, for purposes which will be described below.

It will be seen that this construction allows a number of containers to be placed on the spindles 25 and that these containers will travel throughout the length of the apparatus without any clamping action. During the dipping operation it is, of course, essential that the containers should be caused to assume the desired positions regardless of slight variations in air entrapment and this is accomplished by bringing the outer surfaces of their closed ends successively in contact with guide 21 and then shaft l5. It is desirable that there should be considerable freedom of movement of the containers on the supporting members 26 so that the area included within the ends of these members is preferably substantially smaller than the cross-sectional area of the container to be coated. as shown in Fig. 3, for example.

The particular embodiment of my invention shown in Fig. 1 is especially adapted for coating containers with a thermoplastic material, such as a composition containing a major portion of paraflin wax and a minor portion of rubber having a softening point in the neighborhood of 120-l40 F. Consequently, the receptacle i4 is equipped with a plurality of electrical heating elements 28 of the conventional strig type for the purpose of maintaining the bath of coating material therein at the desired temperature which may be in the case of the particular coating mentioned above about 175-185 F. As a further aid in maintaining the proper bath temperature, means are provided for preheating the containers to be coated comprising a combustion chamber 29 equipped with a gas burner 30, or the like, a blower 3| for propelling the combustion gases into a second chamber 32 and a foraminous baflie 33 so arranged that the hot gases from chamber 32 are directed against the containers on supports 26, as the latter travel upward and then downward into receptacle l4.

Somewhat similar means are likewise provided for maintaining the coated containers emerging from the bath at an elevated temperature for a specified time so as to facilitate draining of the excess coating material therefrom. The arrangement for accomplishing this consists of a second combustion chamber 34 containing a burner 35 and a blower 36 which directs the combustion gases through chamber 31 and foraminous baflie 38 against the coated containers as they travel from the bath up to and along a portion of the horizontal section of the conveying mechanism. The portions of the apparatus just described are preferably insulated to avoid undue loss of heat, and the part thereof underlying the draining section is inclined at a slight angle toward the receptacle l4, so that this material will flow into the bath for reuse. The coated containers then pass from the draining chamber into a cooling section in which they are cooled by means of a blast of air directed through foraminous baflle 39 by means of blowers 40.

In the operation of this embodiment of my invention, the endless chains I0 are caused to move throughout the path previously described and the containers to be coated are placed by hand or otherwise over the spindles 25 and supports 26 at the point indicated by the arrow 4|. These containers then travel in the position indicated upwardly and then downwardly into the pool of coating material and are thus preheated by the hot gases directed through the openings in the baflle 33. Gases of any desired super-atmospheric temperature may be used, but it is preferred in general to use temperatures in the range of -175.

As the containers are about to enter the bath of coating material, their closed ends strike guide 21 which directs them into the bath with their closed ends immediately adjacent shaft l5. The action of this portion of my apparatus can best be seen from Fig. 2, to which reference is now made. In this figure, the dot-and-dash line represents the projection of the path of travel of chains In and the positions of the containers being coated are shown for various positions of the spindles 25 designated as positions A, B, C, and D.

In position A it will be noted that the guide 21 causes the container to be raised somewhat from its position on the supports 26, so that the open end of the container is presented to the surface l6 of the bath and the coating material can begin to flow into the interior of the container. As spindle 25 travels downwardly, this efiect is accentuated until the leading portions of supports 26 are in contact with the leading edge of the container at its closed end and then the container is forced to travel downwardly until it assumes a position similar to position B.

In position B a rather large amount of air is shown as being trapped in the container, but this air will be reduced very considerably or eliminated completely as the spindle 25 continues its movement due to the fact that the buoyancy of the trapped air will cause the open end of the container to swing upwardly and release most, if not all, of the trapped air. It will also be seen that during this stage, namely, just before the container is completely immersed in the bath, its longitudinal axis assumes a substantial horizontal position. The movement of spindle 25 from position B to position C is one of rotation as already described and the container necessarily makes substantially the same rotation.

In position C the container is shown as having a small amount of air trapped therein, but it will be noted that the position of this trapped air is such that it comes in contact with the interior of the container only at those portions of the surface which have previously been in complete contact with the coating material, as for instance, in position B. Consequently, all portions of the interior surfaces as well as the entire external surface of the container is coated. It would be possible to remove the container from the bath in a position corresponding to position using some other type of apparatus, since it has been rotated substantially more than 90 and has had an opportunity to become completely coated, but in the preferred form of my invention as illustrated in Figs. 1 and 2, this rotation is continued and finally the spindle 25 assumes position D in which the container has partially emerged from the bath. In the present instance, the entire rotation of the spindle 25 and, hence, of the container thereon, is approximately 150 and it is preferably somewhat less than 180 and more than 135.

When the spindle 25 and the container carried thereby have traveled beyond position D a sufilcient distance, the opening in the container will be above the liquid level l6 and substantially all of the coating material within the container will drain therefrom. It is preferred, however, to allow a predetermined time for further draining in order that the resultant coating may be uniform and of the desired thickness, and the coated containers, therefore, pass through the draining section shown in Fig. l and described above, in which they are subjected to streams of gas at super-atmospheric temperatures, such as 140?- 175" F. During the horizontal portion of their travel through this chamber, the containers assume the position shown in Fig. 3 due to the difference in height between the leading and fol lowing portions of supporting members 26 and this facilitates the draining operation. Furthermore. the gas streams directed through the openings in baffle 38 cause the containers to be blown from side to side and against spindle 25 which also aids in removing any coating material which i would otherwise accumulate around the lower open end of the container. The containers then pass into the cooling section in which the relatively cool gases directed thereon cause the coating material to dry or otherwise solidify. Finally, as the chains In pass over sprocket IS, the spindles 25 are caused to rotate in such a way that the cool, completely coated containers fall therefrom by the action of gravity.

It will be seen from the above description that I have devised an improved method of applying uniform coatings to containers and novel apparatus {or carrying out this method. It is not p essential in all instances, however, that the containers be preheated prior to the coating operation, and an apparatus embodying my invention omitting the pre-heating arrangement is illustrated in Fig. 8. This apparatus is similar to that already described and corresponding reference characters are used to indicate corresponding parts. Many other modifications can, of course, be made readily by those skilled in the art, falling within the scope of my invention.

While I have illustrated my invention in connection with certain specific embodiments there- Search Roor of, I do not wish to be limited to such embodiments but only by the scope of the appended claims.

I claim:

1. Apparatus for coating tubular containers having one open and one closed end comprising, in combination, a pair o endless chain rnembers, means for causing saidhairr'ih'ribers to move in corresponding horizontally spaced paths, including a downward followed closely by an upward movement, a-plurality of cross pieces at spaced points along the path of travel of said chain members, each of said cross pieces being rigidly secured to one link in each of said chain members, said links being in corresponding positions along said path of travel, at least one container-supporting member rigidly secured adjacent one end to each of said cross pieces with its axis perpendicular to the links associated therewith, the free end of said container-supporting member being in upright position during the transition from said downward to said upward movement, an d a,receptacleadap@.l9.hold a pool of coating material into which containerh placed on said container-supporting means will be immersed by virtue of said downward and upward movements.

2. Apparatus according to claim 1, wherein said container-supporting member has a plurality of prongs at the free thereof, those of said prong in leading position being of greater height than the others.

3. Apparatus according to claim 1 wherein said container-supporting member comprises an upstanding spindle having a plurality of prongs extending laterally from the free end thereof, the distances between the ends of said prongs being substantially less than the corresponding dimensions of the container to be supported thereon, whereby said container can be easily placed over said spindle with its closed end resting on at least some of said prongs and the points of contact between said container and said prongs can shift readily.

4. In apparatus for coating tubular containers having one open and one closed end including a chain conveyor, improved means for supporting said containers comprising an upstanding spindle mounted on said conveyor and a plurality of prongs extending laterally from the free end thereof, the more forward of said prongs being of greater height than the others and the distances between the ends of said prongs being substantially less than the corresponding dimensions of the container to be supported thereon, whereby said container can be easily placed over said spindle with its closed end resting loosely on at least some of said prongs and will rest with its longitudinal axis at a small acute angle to said spindle when said spindle is in vertical position.

5. Apparatus for coating tubular container having one open and one closed end comprising, in combination, a pair of endless chain conveyors, a receptacle adapted to hold a pool of coating material, means for causing said conveyors to move in corresponding horizontally spaced paths, said last-mentioned means including a pair of sprocket coaxially mounted within said receptacle and having said conveyor passing around the lower portion thereof and subsequent guide means for causing said conveyors to travel upwardl and then substantially horizontally, a plurality of cross pieces at spaced points along the path of travel of said conveyors, each of said cross pieces being rigidly secured one link in each of said conveyors, said links being in corresponding position along said path of travel, at least one spindle rigidly mounted on each of said cross pieces with its axis substantially perpendicular to the links associated therewith, each of said spindles having a free end extending toward the axis of said sprockets as their associated cross pieces pass therearound, and a plurality of prong members extending laterally from each of said free ends, the distances between the extremities of said prong members being substantially less than the corresponding dimensions of the container to be upported thereon and those of said prong members extending in the direction of motion of said conveyors being of greater height than the others.

6. Apparatu for coating containers having one closed end and one open end comprising, in combination, an endless conveyor, means, for causing said conveyor to move in a path including a downward followed closely by an upward movement, a plurality of container-supporting members mounted on said conveyor at intervals along said path of travel, each of said container-supporting members being rigidly secured adjacent one end to said conveyor with its axis substantially perpendicular thereto and the free end of each of said container-supporting members being in upright position during the transition from said downward to said upward movement, and a receptacle adapted to hold a pool of coating material into which containers placed on said container-supporting means will be immersed by virtue of said downward and upward movements.

VERNIE A. FOX.

that the said Letters Patent should be re CERTIFICATE OF CORRECTION.

Patent No. 2,558,150. January 0, 191

VERNIE A. FOX.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows: Page 5., secclaim 2, after the word free" insert --end-; end

0nd column, line 50,

ad with this correction therein that the same may conform to the record of the case in the Patent Office Signed and sealed this 5th day of June, A. b. 191

Leslie Frazer (Sea 1) Acting Commissioner of Patents.

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