US2837048A - Method of applying wax to the flange of a can body - Google Patents

Description

W. l. COLVIN June 3, 1958 METHOD oF APPLYING WAX To THE' FLANGE 01@1 A CAN BODY Filed May 17, 1954 2 Sheets-Shea?l 1 W. l. COLVIN June 3, 1958 METHOD OF APPLYING WAX TO THE FLANGE OF A CAN BODY 2 Sheets-Sheet 2 Filed May 17, 1954 INVEN TOR. W/LL/AM l. 00L V//v B aga@ ATTORNEY METHOD oF APPLYING WAX' 'ro THE FLANGE oF A CAN BODY;

Application May 17, 1954, No. 430,077

2 Claims. (Cl. 113-,-120) This invention relates to new and improved apparatus and method for coating the inside of flanges of can bodies with a protective lm of parain wax to prevent break-down of the can lining when it is filled with highacid liquids such as carbonated soft drinks. The invention also relates to a flanged can body coated with wax in a band of restricted area.

One of the recent developments in the application of cans to new products is the increasing use of such containers for packaging carbonate-d 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 enamelsy andtin 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 tocoat the inside of the can to reduce the tendency toward leakage and thicker layers of tinpiate 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. yTwo principal reasons for this break-down at the crevice with which this invention is concerned are: first, working of the metal and enamels during Hanging of the can body and double seeming of the end to the can body causes break-down of enamels, tin and steel; second, when the can ends are deposited on top' of the flanged end of th'e can body in the can closing machine whichdouble seams the ends onto the body, the inturned-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,

most effective under controlled conditions. 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 anges of the can bodies in the precise zone described as the cans move along existing-conveyer lines in their progress to the can closing machine. Thus, the apparatus hereinafter described is installed with a minimum of changeover requiredfrom existing conveyer lines in can manufacturing or in can filling plants.

the scratches lea-ding to eventual break-down after the f acid contents of the beverage have been in contact'with them for a prolonged period of time. v

The present invention involves ythe applicationof a,

coating of paraflin wax to the inner surfaceof the'body in the zone from the outer edge of the flange to alevel approximately at the level of the commencement 'of the outward flaring of the flange.

The application of paraffin wax in the zone lindicated results in lubricating the flange and the end during double seaming, this lubricating effect reducing 'the detrimental eifects 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 anextra coating at the zone most likely to break down, which coating augments the protection afforded by the enamels and tinplate. p I

Oneadvantage of the'present invention is the fact that ous layers of material above the tin plate being strippedv aw'ayto 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 waxto the hanged 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 4in the manufacture of a can body in accordance with th present invention.

The can 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;4 The base 14 of the body is steel covered withy a coating of tin. The tinplate which forms the blank from which the body is fabricated is coated in at con-I4 dition with a primer vinyl resin lm 16 which is baked at a high temperature to solidify and set the vinyl resin. During manufacture of the cylindrical body from the at blank, a soldering operation is performed on the out-- side of the side seam, the heat of which breaks down the primer coat.

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 exible, tough, highadhesive, acid-resistant resin, this resin being exible and thus resists the tendencyto break down under the ilex- .1 Patented June3, 1958 Excess wax Accordingly, after the side seam completed, a stripe 17 of vinyl resin is sprayed on thel 3 ing which takes place when the double seaming operation is performed.

The can ends 21 are likewise formed of a soft-tempered tinplate 22 and are` further coated, first with a primer coat 230i a vinyl resin and then witha -second coat v'24 of leXible, tough, high-adhesive, acid-resistant resin. Thecan Vend is fabricated with -a trough 26 which is an annular depression formed in the end adjacent its periphery and with an inwardly curled outer flange -27. The trough 26 is lled with la lining compound '18 having a `rubber base, as is well understood in this art.

Can bodies 11 as thus coated, and can ends 21 as heretofore described, when double-seamed together in conventional closing machinery, have been found satisfactory insofar as resistance to high-acid, carbonated beverages is concerned, lwith 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 land -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 Adescribed is the deposit on the flange of the can body of a band 31 of paraffin wax. As shown particularly in Figs. l and 3, this band covers the inside of the cau body from the raw edge `32 of the ange up inside of the body to about the line 33 at which-the'ange turns outwardly. (See particularly reference `numeral 33, Fig. 3.) This band 31 of paraffin wax protects the underlying enamels yand tin plate in several respects. In the lrst place, if the inturned raw edge 27 of the curl of the ange of the can 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 ange of the can end and the ange of the can body during the double scaming operation which forms 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 Vmolten .paraffin wax, the wax does not freeze thereon immediately upon contact with cold can bodies. lt will be understood that various other means may be employed to heat the can flanges.

A rotatingtstar wheel 38 having a plurality of peripheral semi-circular pockets revolves clockwise adjacent the end of the conveyer, each can body in`turn being received .in a pocket and carried Iaround 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 a arcuate 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 las hereinafter described. It is desirable that the can 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 y'into `the felt surface 446 of 4the paraffin vcli-sk 47 within pan 44 on which they are subsequently deposited. The star wheel 38 is mounted on a vertical spindle 48 which-fis driven by belt 49 and pulley 51 from a motor (not shown). Also mounted on the spindle 48 is a gear 52 which meshes with gear 53 on spindle 54 which carries wax applicator disk 47 so that the star 38 Iand the wax applicator disk 47 revolve insynchronisrn. A dislodger 56 on the top and bottom surface of .the star wheel-is provided to scrape the can bodies out of contact with the magnets-42 and release them from the pockets 39 of the star wheel. Each of the dislodgers 56 comprises a flat, horizontal bar lying adjacent the discharge area of the star wheel, the bar having a rounded terminal 57 which engages the can bodies and forces them tangentially outwardly from the pockets.

The paraffin-applying vdisk 47 comprises a at horizontlly disposed disk Ymounted for rotation on spindle 54, the disk being perforated in a plurality of small vertical 'holes S8 and lcovered on its top surface with a layer of felt 46 or similar material. Surrounding the paran-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 paraiin wax is introduced through a hole in the bottom of pan 44 through tube 61. A dischangeaperture 62 isprovided in the side wall 43 of .the'pan 4'41atfa level .about midway of the height of the disk 47, 'the 'discharge aperture providing au overow 'forlthefmolten wax so that it rises no higher than about the midpoint of the rotating disk. The wax owing out .of the .overow is returned by tube 63 to a storage tank 64 which is Ain turn in communication with a heater .66 which heats the wax to a proper temperature and a pump 67 which pumps the waxinto .the inlet rttibe '-61. Thus, the molten wax is in contact with the apertures 58 in the .disk 47 and rises by capillary action lto the top surface where it wets the felt 46 with molten aparan.

Reverse curved 1inner' and outer can guides 68 and 69 are 'provided elevated above the surface of disk 67 which direct the can bodies 11 discharged by the dislodging devices 56 so that they are guided around the periphery of the rotating disk 47 and are directed oif the disk after having traveled through an langular travel of Vapproximately 90.

The can bodies, after having been coated with a band 31 .of wax, by the means heretofore described are then deposited on a conveyer 71. From the conveyer 71 the bodies are -rotated by a conventional can turnaround Iso `that the waxed ange 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 11 are then again rotated through 180 by -a 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 `wax runs down into and fills the crevice, thereby protecting the crevice 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 anged, lined can bodies 11 are received in conveyer 36 and heated by heater 37. Each body is in turn deposited in a pocket 39 in the star wheel 38, being held atan elevated position by the magnet 42 associated Vwith each pocket. The cans are carried around on the star wheel over the edge 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 ,paran disk 47. Centrifugal force causes the can bodies .to move outwardly `toward the periphery of the wheel `and guided by outer guide 69, the can bodies thus coming in 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 yparticularly in Fig. 5. The hot wax rises by capillary action through the holes 58 in the .disk 47 and wets the felt surface 46. The constant circulation of hot wax from the tank 64 through the heater 66, kthrough the ,pump 67 to the `pan 44 and out-theoverowzbackto the tank 64, insures that the wax is maintained in the pan at proper temperature 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 solidies gradually) lcauses the adherence of a band 31 of wax best illustrated in Fig. 3. This 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 of the closing machine 73 to which the can bodies are later transferred. The wax covers the ange 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 anges 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 ange of the body. After the end 21 is deposited on the can body 11, it is doubleseamed to form seam 34 in conventional manner, the wax 31, however, lubricating the seam so that breakdown 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 iilling 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 lled 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. 5 to 7. Thereupon the cans are rotated through 180, lled, 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. A method of applying wax in a restricted band on the inside of the flange of a langed can body, comprising preparing molten wax, continuously revolving a feltlike surface substantially horizontally, applying molten wax to said surface from below the surface by capillary action, positioning a can body in proximity to said surface with an open end downward, continuously moving said open end across and parallel to said surface as said surface revolves and with said open end resting upon said surface under the attraction of gravity to coat the inside of the flange from its outer edge to the level of the beginning of the outward are of said flange with a band of wax, withdrawing said body from contact with said wax, and allowing said wax to solidify on the inside of said anged end of said body.

2. A method of applying wax in a restricted band on the inside of the flange of a flanged can body, comprising preparing molten wax, continuously revolving a feltlike surface substantially horizontally, applying molten.

wax to said surface from below the surface by capillary action, positioning a can body in proximity to said surface with an open end downward, continuously moving said open end across and parallel to said surface as said surface revolves and with said open end resting upon said surface under the attraction of gravity to coat the inside of the flange from its outer edge to the level of the beginning of the outward are of said liange with a band of wax, withdrawing said body from contact with said wax, and allowing said wax to solidify on the inside of said anged end of said body, double-seeming a can end onto the end of said body to which said wax is applied and heating said body to allow wax of said band of wax above the crevice where said end and body come together to melt and run down into said crevice.

References Cited in the le of this patent UNITED STATES PATENTS 831,905 Thom Sept. 25, 1906 1,946,428 Preston et al Feb. 6, 1934 1,977,090 Schibsted Oct. 16, 1934 2,028,798 Murch Jan. 28, 1936 2,110,938 Nutt Mar. 15, 1938 2,154,349 OBrien Apr. 11, 1939 2,169,816 Pfeifer Aug. 15, 1939 2,214,435 ONeil Sept. 10, 1940 2,299,090 Hothersall Oct. 20, 1942 2,413,093 Warth Dec. 24, 1946 2,645,200 Schweitzer July 14, 1953

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