US2345852A - Shot shell sealing - Google Patents

Description

i 1944 c. M. LANGKAMMERER 4 SHOT SHELL SEALING Filed April 10, 1942 INVENTOR U2 1%. Lang/ff [1mm are AGEN T SHOT SHELL SEALING Application April 10, 1942, Serial No. 438,423

- 6 Claims.

This invention relates to the securing of adhesive or sealing materials to waxed surfaces or.

wax-impregnated bodies,- and will be described with particular reference to the securing of face are shownand described in the co-pending' application of Hackman 382,689, filed March 11, 1941. Apparatus for afilxing a thermoplastic adheslve, preferably carried on a paper disk, to shot shells as they are delivered from the loading machine, is illustrated in the copending application of Reynolds, Serial No. 291,106, flied August -19, 1939 and issued as Patent No. 2,286,159.

While the method of forming a moisture-proof end-closure for fiat top shot shells, disclosed in the ,above identified applications, has been used extensively in regular production, some difficulty has been encountered in obtaining a uniformly satisfactory seal at the maximum temperature,

. pressure and time of dwell permissible on the aiiixing equipment. It has been found desirable, therefore, to improve the seal and at the same time reduce the temperature and time required to eiiect good adhesion. 'The present invention comprises the discovery that superior adhesion can be secured and the closing process simplifled and cheapened by the use of an appropriate solvent for the adhesive' It is, therefore,an object of this invention to provide an improved method of securing an adhesive to a wax-impregnated material. A further object is to provide a method and means for securing a thermoplastic coated paper disk to the closure of a shot shell using a solvent for the thermoplastic.

Other objects, features, and advantages will be manifested-in the following description.

In the drawing: i r

.Fig. 1 illustrates, diagrammatically, one form of the apparatus which may be utilized in the practice of applying a solvent which assists in the bonding of a thermoplastic adhesive to a wax-impregnated surface, such as a shot shell closure. I

Fig. 2 is a front elevation of a device for applying the solvent to the shot shell closure. I

Fig. 3 is a perspective view of an element of the solvent applying device of Fig. 2.

Fig. 4 is a cross section of a modification of a solvent applying device of Fig. 2.

The apparatus shown comprises a conveyor belt Ill onto which shot shells H are delivered from a loading machine I2 and from which they are removed laterally, preferably in pairs, to positions beneath a pair of disk punches 13 which cut sealing disks from a strip of paper it coated with a thermoplastic adhesive, and preliminarily afilx these disks to the shot shells. The closure portion of the" shot shells may or may not be abraded, it being understood that the method of the present invention is applicable in either circumstance. The pair of shot shells with the disks partially afilxed thereon are then transferred to positions beneath a pair of heated plungers I5.where theafllxing of the sealing disk is completed.- The present invention contemplates the application of a solvent for the ther I the paper strip.

The means for applying the solvent to the shot shell closure comprises an applicator or similar coating device, indicated generally at IS. A tubular post I9 is threadedly secured by a valve unit 22 into the upper end of the coating device l6 and connected at its upper end to the'solvent supply tank 20 byconnecting tubing 2| and a valve unit 23. By means of the valves 22 and 23, the flow of solvent from the tank 20 to the device l6 may be maintained substantially constant.

The post 19 is carried at the extremity of an arm of a bracket I l which is fastened to the reciprocating block 18 of the disking punches l3, whereby the coating device I6 is raised and lowered, with the motion 0f 'the block 18, from and into contact with the shot shell closures. Suitable nuts 24 on the threaded portion of the post i9 provide means for raising and lowering the post in the bracket and thus adjusting the applicator to shells of different lengths Referring to Fig. 2, the coating device '6 comprises a substantially rectangular block 25 01'. metal such as brass or any other suitable material drilled and threaded as at 26. The lower half of the block is milled transversely so as to reduce its thickness and form shoulders 27, 21 as indicated in Fig. 3. A'hole 28, which may be of somewhat less diameter than hole 26, is drilled in the lower portion of the block and communicates with the hole 26 so as to conduct the liquid solvent bristles project.

from the connecting tubing 2| through the block 25 into an applicator 30. 1 The latter is shown as a vU-shaped block of resilient material such as sponge rubber notched; on its bottom surface, as

at 3|, so as to form two spaced, work- engaging pads 32, 32 and secured on the endof the block 25 by a metal band 33. The latter embraces the block of sponge rubber adjacent the lower thinned portion of the metal block 25 and is bound securely thereto with its upper edge 3 abutting the shoulders 21, 27 of the block 25. It

will be clear that the liquid solvent passing down through the orifices 26 and 28 of the block 25 saturates the sponge rubber so that whenever the sponge is lowered into engagement with the shot shell closures of a pair of shot shells, the pads of surfaces 32 wet the fiat top closures with the solvent.

Although the coating device i8 is shown substantially rectangular, it will be understood that the block 2d and sponge rubber applicator 38 may be made substantially cylindrical or otherwise modified without exceeding the scope of thenvention as defined in the appended claims. .In this respect, attention is directed to Fig. 4 which shows an applicator comprising a block 25' provlded with the usual rubber-set bristles 40 of any well-constructed paint brush.. The block 25' is adapted to be supported by the bracket H which. in this instance, may be bolted to a fixed part of the frame so that the brush d0 will-be held in a predeterminedposition "with respect to the horizontal plane defined by the fiat top closures of the shot shells. The solvent is conducted to the bristles through a plurality of small holes dl drilled down through the rubber bristle-setting block 42. The rubber binding of the bristles may be replaced by any other binding not adversely affected by the solvent.

In order that the bristles shall spread the solvent uniformly over the tops of the shot shells and to avoid spattering, a metal shoe 13 is secured upon the lower end of the block d2 and'provided with an open toe portion 84 through which the The toe portion is adapted to bend the bristles in the direction of travel of the shot shells so as to enhance smooth and uniform coverage by the solvent.

Although the above described apparatus is arranged to apply the solvent to the top of the shot shell, it will be apparent that a similarly effective bond may be secured by modifying the applicator supporting means so that the solvent may be applied directly to the adhesive on the underside of the paper strip M.

The solvent may be selected with reference to the particular adhesive-for example, with an adhesive of plasticized ethyl cellulose, excellent results are secured with iso-propyl alcohol. Other suitable thermoplastic adhesives are methyl cellulose, butyl cellulose. and benzyl cellulose; cellulose acetate and cellulose acetate-butyrate; polyvinyl acetate and its interpolymers; polyvinyl acetals such as polyvinyl acetal, polyvinyl butyral and polyvinyl isobutyral; polyacrylic with plasticizers, softeners andother resinous or polymeric materialsmay be employed.

In general, solvents of thermoplastic adhesives include acids, alcohols, ketones', esters, ethers, aromatic and chlorinated hydrocarbons, and mixtures thereof. 'Among such solvents, usable singlyor in suitable admixtures, are carbon tetrachloride, trichloroethylene, tetrachloroethylene, toluene, ethyl alcohol, butyl alcohol, isopropyl alcohol, and methyl CellosolvB; the latter is 'a well known commercial term for a composition'ofalcohol and ether identified as ethyl glycol monomethyl ether.

By way of illustration'only, one example of the practice of the invention using a paper strip 7 coated with plasticized ethyl'cellulose is as follows! A thin film of iso-propyl alcohol is first applied to the closure by one of the above described applicators and thereafter resin coated disks are simultaneously punched from the adhesive strip and pressed on the flat top of the shell. subse-l quently the disks are again subjected to pressure, this time by heated plungers which 'complete the bond between the thermoplastic adhesive and the shot shell closure.

The application of the small amount of solvent acid esters such as polymethyl methacrylate.

before aiiixing the adhesive disk, allow svthe use of lower temperatures, for the pressing plungers which is very desirable'because of the explosive nature of the shells being sealed and the consequent hazard of employing high temperatures near shell loading equipment. In addition, the

strength of the bond is increased from fair to excellent and the solvent permits the use of high softening, resinous adhesives which do not exude from the seal during firing so as to deposit on the Wa1ls of the firing chamber. Furthermore, the diski'ng punches may be operated substantially cold instead'ot at an elevated termperature as heretofore practiced, thus insuring smoother feeding of the adhesive tape through the cold guides and longer life of thecutting edges of the dishing punches.

What is claimed is: 1. The method of securing a. thermoplastic adhesive seal to a wax-impregnated paper body comprising the stepsoi applying a solvent for the adhesive of said seal to said body. pressing said' sealinto contact with the solvent coated surface of said body to preliminarily secure the seal thereto and subsequently applying a heated plunger 'to said'seal to permanently afilx said seal by heat to said wax-impregnated paper body. 2. The method of sealing the closure of a shot shell with an adhesive composition comprising the steps of abrading the closure forming a portion of the body, applying to the closure 8. solvent for the adhesive, pressing a disk coated with the adhesive into contact with said solvent and said closure and subsequently applying heat and pressure. to said disk to permanently secure it to said closure.

3. In the sealing of the closure ofshot shell bodies with an adhesive of plasticized ethyl cellulose, the methodwhich comprises the steps of moistening the closure with iso-propyl alcohol. pressing into contact with said moistened surface a body bearing an adherent coating of plasticized ethyl cellulose to preliminarily secure said body to said closure and subsequently applying heat and pressure to said body to permanently and methyl Cellosolve, preliminarily securing the.

to a wax-impregnated paper body comprising the steps of applying to said body a thermoplastic solvent selected from the group consisting of carbon tetrachloride, trichloroethylene. and tetra chloroethylene, preliminarily securing the thermoplastic seal to said coated surface by said solvent, and then permanentl amxing the thermoplastic seal to said coated surface by pressure and heat.

5. The method of securing a thermoplastic 10 seal to a wax-impregnated paper body comprising the steps of applyi to the body a thermoplastic solvent selected from the group consisting of ethyl alcohol, butyl alcohol, iso-propyl alcohol.

thermoplastic seal to said coated surface by said solvent, and then permanently affixing the ther-' moplastic seal to said coated surface by pressure and heat.

6. The method of securing a thermoplastic seal to a wax-impregnated Daper'body-compris ing the steps of moistening the body with toluene, preliminarily securing the thermoplastic seal to the moistened surface by said toluene. and then permanently afflxing the thermoplastic seal to said moistened surface by heat.

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