US2902001A - Apparatus for coating the inside of flanges of can bodies - Google Patents

Description

W. l. COLVlN Sept. 1, 1959 APPARATUS FOR COATING THE INSIDE OF FLANGES 0F CAN BODIES Original Filed May 17, 1954 2 Sheets-Sheet 1 IN V EN TOR.

WILLIAM], C //v 2 74 ATTORNEY s p 1959 0 w. l. COLVIN 2,902,001

APPARATUS FOR COATING THE INSIDE OF FLANGES 0F CAN BODIES Original Filed May 17, 1954 2 Sheets-Sheet 2 CLOSING MACHINE.

IN V EN TOR.

/ o'runu WILL/AM c w yf' 7 4 M ATTORNEY United States Patent APPARATUS FOR COATING THE INSIDE OF FLANGES OF CAN BODIES William I. Colvin, Los Altos, Calif., assignor to National Can Corporation, Chicago, Ill., a corporation of Delaware Original application May 17, 1954, Serial No. 430,077,

now Patent No. 2,837,048, dated June 3, 1958. Divided and this application January 21, 1958, Serial No. 710,304

4 Claims. (Cl. 118-230) This invention relates to new and improved apparatus for coating the inside of flanges of can bodies with a protective film of paraffin wax to prevent break-down of the can lining when it is filled with high-acid liquids such as carbonated soft drinks. Reference is made to co-pending application, Serial No. 430,077, now Patent No. 2,837,048, of which this application is a division.

One of the recent developments in the application of cans to new products is the increasing use of such containers for packaging carbonated soft drinks, thereby replacing the bottles formerly universally employed. A principal problem in the packaging of many types of carbonated soft drinks is the fact that the high acid content combined with the higher than normal pressure within the can, causes failure of the container. The high acid liquids tend to corrode the enamels and tin and steel which form the can body, resulting in the transfer of an undesirable metallic taste to the contents and eventually to leakage.

Special enamels have been developed to coat the inside of the can to reduce the tendency toward leakage and thicker layers of tinplate and special tempers of steel have been employed. Nevertheless, failures have occurred, particularly at the bottom of the can in the crevice where the end and the body come together. Two principal reasons for this break-down at the crevice with which this invention is concerned are: first, working of the metal and enamels during flanging of the can body and double seaming of the end to the can body causes break-down of the enamels, tin and steel; second, when the can ends are deposited ontop of the flanged end of the can body in the can closing machine which double seams the ends onto the body, the intu'rned raw edge on the end (which has a close fit with'the outside diameter of the flange of the body) comes in contact with the inside of the flange and scratches the enamel on the flange, the scratches leading to eventual break-down after the acid contents of the beveragehave been in contact with them for a prolonged period of time.

The present invention involves the application of a coating of parafiin wax to the inner surface of the body in the zone from the outer edge of the flange to a level approximately at the level of the commencement of the outward flaring of the flange.

The application of paraflin wax in the zone indicated results in lubricating the flange and the end during double seaming, this lubricating effect reducing the detrimental eitects of the mechanical working of the end and flange. Another desirable result from the application of wax in the zone indicated is the fact that the wax protects the underlying enamel from scratching when the end is deposited on the body in the closing machine. Further, the wax provides an extra coating at the zone most likely to break down, which coating augments the protection afforded by the enamels and tinplate.

One advantage of the present invention is the fact that the wax is applied only in a specific location where it is most effective under controlled conditions. Excess wax 2,902,001 Patented Sept. 1, 1959 ICC is applied so that the mechanical difficulty which would arise were wax to cover the chuck of the closing machine is avoided. It will be understood that a coating of wax on the chuck of the closing machine would interfere with proper operation inasmuch as the can would spin rather than being properly gripped by the chuck. Another feature and advantage of the application of the wax in the pattern herein described is the fact that the wax is applied only where it is most effective, thereby economizing in the cost of wax. Still another feature of the pattern of application is the fact that no unsightly layer or beads of wax is observable in the interior of the can.

Another feature of the present invention is the fact that there is a continuous application of wax to the flanges of the can bodies in the precise zone described as the cans move along existing conveyor lines in their progress to the can closing machine. Thus, the apparatus hereinafter described is installed with a minimum of change-over required'from existing conveyor lines in can manufacturing or in can filling plants.

Still another feature of the invention is the simplicity and low cost of manufacture and operation of the apparatus and its freedom from requirement of supervision and maintenance.

Other objects of the present invention will become apparent upon reading the following specification and referring to the accompanying drawings in which similar characters of reference represent corresponding parts in each of the several views.

In the drawings:

Fig. 1 is a schematic perspective view of a flanged can body formed in accordance with this invention, the various layers of material above the tin plate being stripped away to show the construction.

Fig. 2 is a schematic plan view of a can end, the various layers of material being stripped away to show the construction.

Fig. 3 is an enlarged sectional view of the flanged can body formed in accordance with this invention.

Fig. 4 is a section through the double seam whereby the can end is seamed to the can body formed in accordance with this invention.

Fig. 5 is a top plan of apparatus for applying the wax to the flanged can bodies.

Fig. 6 is a vertical section taken substantially along the line 6-6 of Fig. 5.

Fig. 7 is a schematic plan view illustrating steps in the manufacture of a can body in accordance with the present invention.

The cam body 11 employed in the present invention comprises a cylinder of metal provided with a side seam 12. As shown in Fig. 1, conventional flanges 13 are formed at either end of the body for the purpose of cooperation with the can ends which are double seamed thereto. The base 14 of the body is steel covered with a coating of tin. The tinplate which forms the blank from which the body is fabricated is coated in flat condition with a primer vinyl resin film 16 which is baked at a high temperature to solidify and set the vinyl resin. During manufacture of the cylindrical body from the fiat blank, a soldering operation is performed on the outside of the side seam, the heat of which breaks down the primer coat. Accordingly, after the side seam is completed, a stripe 17 of vinyl resin is sprayed on the area on the inside adjacent the side seam 12. After the side stripe 17 is applied, the entire body is sprayed with a coating 18 of a special flexible, tough, high-adhesive, acid-resistant resin, this resin being flexible and thus resists the tendency to break down under the flexing which takes place when the double seaming operation is performed.

tinp'late 22 and are further coated, first with a primer coat 23 of a vinyl resin and then with a second coat 24 of flexible, tough, high-adhesive, acid-resistant resin. The can end is fabricated with a trough 26 which is an annular depression formed in the'end adjacent its periphcry and with an inwardly curled outer flange 27. The trough 26-is filled with a lining compound 18; having a rubber base, as is well understood in this art.

7 Can bodies 11 as thus coated, and can ends 21 as heretofore described, when double-seamed together'in con ventional closing machinery, have been found satisfactory insofar as resistance to high-acid, carbonated beverages is concerned, with the exception of the fact that the high citric and phosphoric acids in certain carbonated soft drinks sometimes results in a break-down in the crevice 29, where the end and the body come together. The present invention is, therefore, concerned with remedy of this situation.

The apparatus illustrated in Figs. to 7, inclusive, is subject to considerable modification. The end result of the use of the apparatus of the method hereinafter described is the deposit on the flange of the can body of a band 31 of paraffin wax. As shown particularly in Figs. 1. and 3, thisband covers the inside of the canbody from the raw edge 32 of the flange up inside of thebody to. aboutthe line 33 at which the flange turns outwardly. (See particularly reference numeral '33, Fig. 3.) This band 31 of paraffin wax protects the underlying enamels andtin plate in several'respects. In the first place, if the inturned raw edge 27 of the curl of the flange of the pan end is deposited on the can body and comes in contact with the inner part of the body as it frequently does, it contacts the wax rather than the enamel. In the second place, the wax lubricates the flange of the can end and the flange of the can body during the double seaming operation whichforms, the double seam 34 and hence reduces the likelihood ,of break-down.

Turning now to the specific apparatus illustrated in Figs. 5 to 7, inclusive, the can bodies '11, after having been flanged, travel down the conveyer 36. A tubular infra-red heater 37 is installed under the conveyer on which the cans move, the function of the heater being to warm the flanges 13 of the bodies so that when they come in contact with the molten paraflin wax, the wax does not freeze thereon immediately upon contact with cold can bodies. It will be understood that various other means may be employed to heat the can flanges.

A rotating star wheel 38 having a plurality of peripheralsemi-circular pockets revolves clockwiseadjacent the end of the conveyer, each can body, in turn being received in a pocket and carried around in a clockwise direction as indicated in Fig. 5. Desirably, each pocket is formed with horizontal vertically spaced radial fingers 41 which contact and move the bodies 11 in an arcua te path. Each pocket of the star wheel is desirably provided with a strong, horseshoe, permanent magnet 42 which causes the body to adhere in the pocket until it is scraped off as hereinafter described. It is desirable that the vcan bodies be held elevated in the individual pockets in the star wheel so that the bodies clear the upper edge of the side 43 of pan 44 and also so that the sharp edges 32 of the can body flanges do not dig into the felt surface, 46 of the paraffin disk 47 within pan 44 on which they are subsequently deposited, The star wheel 38 is mounted on a vertical spindle 48 which is driven. by belt 49, and pulley 5-1 froma motor (not shown). Also mounted on the spindle '48 is a gear 52 whichmeshes with gear 53 on spindle 54 which carries wax applicator disk 47 so that thestar38 and the, wax applicator disk 47 revolve, in synchronism. A,dislodger.56 pn the top and botto rnsurfaceofthe star wheel is provided to scrape the can bodies outof contact with the magnets 42 and releasethem from hgpq ets 9f he, tar e E cl Qf-t e i lod e s 56 comprises a flat, horizontal bar lying adjacent the d ssl arsearca of the starwhee the ba aviusamun ed terminal 57 which engages the can bodies and forces them tangentially outwardly from the pockets.

The paraifin-applying disk 47 comprises a flat horizontally disposed disk mounted for rotation on spindle 54, the disk being perforated in a plurality of small vertical holes 58 and covered on its top surface with a layer of felt 46 or similar material. Surrounding the paraflin-applying disk is a circular pan 44 having upturned sides 43, the upper edges of which are elevated above the top surface of disk 47. Spindle '54 is suitably journalled in the pan, a seal and bearing 59 being provided. Hot molten paraflin wax is introduced through a hole in the bottom of pan 44 through tube 61. A dis.- charge aperture 62 is provided in the side wall 43 of the pan 44 at a level about midway of the height of the disk 47, the discharge aperture providing an overflow for the molten wax so that it rises :no higher than about the midpoint of the rotating disk. The wax flowing out .ofthe overflow is returned by tube 63 to a storage tank 64which is in turnin communication with a heater 66 which heats the wax to a proper temperature and a pump 67 which pumps the wax into the inlet tube 61. Thus, the molten wax is incontactwith the apertures. 58 in the disk 47 and risesv by capillary action to the .topsurface where it wets the felt .46. with molten parafiin.

Reverse curved inner and .outer can guides 68- and 69 are provided elevated above the surface of disk 67 which directthe. can bodies 11 discharged by the dislodging devices56. so that they are guided around the periphery of the rotating disk 47 and are directed off the disk after having traveled through an. angular travel of approximately The can bodies, after having been coated with a band 31 :of wax, by the means heretofore described are then .depositedon a conveyer 71. From the conveyer 71 the bodies are rotated by a conventional can turnaround so that the waxed flange is uppermost. The bodies are then received in a conventional can closing machine 73 which forms double-seam 34 of the can end 21 onto the body 11. The cans llare then again rotated through 180 bya turn-around 74 and passed over a heater 76 which may be similar in construction to heater 66. The function of heater 76 is to melt whatever wax remains visible in the can body above the crevice 29 at the juncture of the body and the can end. The molten waxruns down into and fills the crevise, thereby protecting thecrevice against the corrosive action of the contents subsequently filled into-the can body. Further, as the wax runs down into the. crevice, it prevents an unsightly residue from remaining.

In operation, the flanged, lined can bodies 11 are received in conveyer 36 and heatedby heater 37. Each body is in turn deposited in a pocket 39 in the star wheel '38, being held at an elevated position by the magnet 42 associated with each pocket. The cans are carried around on the star wheel over theedge of the pan 44 and are then dislodged by means of 'dislodgers 56 which cause the can bodies to be lowered to the felt surface 46 of the parafiin disk 47. Centrifugal force causes the can bodiesto move outwardly toward the periphery of the wheel and guided by outer guide .69, the can bodies thus .comingin contact with the paraffin on the felt 46. The. guides 68 and 69 confine. the path of the can bodies to a reverse curve as illustrated particularly in Fig. 5. The .hot wax rises by capilla y action through the holes 58in the disk 47 and wetsthe felt surface 46. The constant circulation of hot waixfrom the tank I64 through the heater 66, through the purnp67 tothe pan .44 and out the overflow 62 back to the tank 64, insures that the wax is maintained in the pan at proper temperatures slightly above its melting point.

The relatively cool can bodies 11 (the temperature of the flanges 13 being high enough so that the wax does not freeze thereon but being low enough so that it solidifies gradually) causes the adherence of a band 31 at t ustrated n fie i band 31 does not cover any of the outside of the can body and thus prevents any wax from coming in contact with the chuck f the closing machine 73 to which the can bodies are later transferred. The wax covers the flange 13 from its extreme outer edge 32 inwardly and upwardly around the curve of the flange to about the level 33 of the beginning of the curve.

The can bodies 11 having waxed flanges 13 are then turned over through 180 by turn-around 72 so that the waxed end is uppermost and carried into the closing machine 73. In the closing machine a can end 21 is deposited on the open end of .the can. During the depositing operation the Waxed band 31 protects the flange 13 from scratching when, as almost invariably happens, the sharp inturned edge 27 of the curl of the can end comes in contact with the flange of the body. After the end 21 is deposited on the can body 11, it is double-seamed to form seam 34 in conventional manner, the wax 3-1, however, lubricating the seam so that break-down of the enamels 16 and .18 and 23 and 24 is avoided. After the can ends have been applied, .the can bodies are again rotated through 180 by turn-around 74 so that end which is closed is undermost, the cans passing over a second heater 76 in this position which causes the wax which remains above the level of the crevice 29 at which the end and the body come together to melt and to run down into the crevice, thereby filling the crevice, protecting it against the acid in the beverages subsequently filled in the can body and further preventing unsightly wax from remaining visible.

It is generally unnecessary to provide wax on the flange 13 of the opposite end of the can for the reason that cans are generally stored after filling with the end applied at the can factory downmost. A head space exists in the upper end of a can of carbonated beverage and hence the danger of high-acid contents coming into contact with the crevice between the upper end of the can and the can body is largely eliminated. However, if it is desired to apply wax to flanges at both ends, before the cans are filled with carbonated beverages they are brought onto a conveyer similar to conveyer 36 with the open end downmost. The star wheel 38 and Wax applying disk 47 perform their function exactly as shown in Figs. to 7. Thereupon the cans are rotated through 180, filled, and the upper ends 21 seamed on in conventional manner. The last turning and heating operation is eliminated.

Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is understood that certain changes and modifications may be practiced within the spirit of the invention and scope of the appended claims.

What is claimed is:

1. Apparatus for applying a band of wax to the inside of flanges of flanged can bodies comprising a perforate disk, means for rotating said disk in a horizontal plane, a felt-like covering on the top surface of said disk on which said bodies rest, means for supplying molten wax below said disk to rise by capillary action through the perforations in said disk to said felt surface, means for feeding *bodies with their axes vertical onto said felt surface one at a time in upright position, means for guiding said bodies upright over the top surface of said disk for a portion of its angular travel while said disk rotates, and means for discharging said bodies from said disk after having been in contact with said felt-like covering as said disk rotates.

2. Apparatus according to claim 1 which further comprises a multi-pocketed star wheel, a magnet in each said pocket to retain a can body in each pocket against vertical displacement, a dislodger associated with said star wheel positioned to discharge bodies from said star wheel onto said felt-like covering of said disk, and means for rotating said star wheel.

3. Apparatus according to claim 2 in which the level of the said star wheel is above the level of said disk.

4. Apparatus according to claim 1 which further comprises a heater to heat at least one flange of each body in proximity to said means for feeding bodies onto said felt surface.

References Cited in the file of this patent UNITED STATES PATENTS 831,905 Thom Sept. 25, 1906 1,225,649 Kronquest May 8, 1917 1,946,428 Pres-ton et a1. Feb. 6, 1934 2,521,817 Andresen et a1. Sept. 12, 1950 2,531,914 'Lager et al Nov. 28, 1950 2,741,219 Montalcini Apr. 10, 1956 2,837,048 Colvin June 3, 1958 2,868,373 Renard et al. Jan. 13, 1959 FOREIGN PATENTS 929,798 Spain Aug. 3, 1909

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