US1455364A - Method of manufacturing iwner tubes - Google Patents

Description

May 15, 1923.

R. E. STEPHENSON METHOD OF MANUFACTURING INNER TUBES Filed Sept. 5, 1921 Patented Ma 15, 1923.

UNl'l'ED STATES RALPHE. STEPHENSON, F INDIANAPOLIS, INDIANA, ASSIGNOR TO G. COMPANY, A CORPQEATION OF INDIANA.

86 T. TIRE METHOD OF MANUFACTURING INNER TUBES.

Application filed September 3, 1921. Serial No. 498,286.

To all whom it may concern:

Be it known that I, RALPH E. STEPHEN- SON. a citizen of the United States, residing at Indianapolis, county of Marion, and State of Indiana, have invented a certain new and useful Method of Manufacturing Inner Tubes, of which the following is a full, clear, and exact description.

This invention relates to an inner tubetor pneumatic tires and its method oi manufacture.

It is desirable to incorporate what I is" .lmown as a valve base around the opening in an inner. tube "for themetal valve stem by Which it is inflated. The valve base is usually made of one or more (usually 2 or" 3) plies of super-posed fabric. Thetubes .of green stock are formed preparatory to vulcaniz'ationin various Ways but most generally and economically by rolling'a sheet oi the proper dimensions around a pole a suitable number of times and the valve base, or patch asitmay be called,'is generally ap,

plied to the front or first-coiled edge of the sheet in such wise as to locate the base in direct contact with the pole? Frequently, air is entrapped at or in the vicinity of the patch in this method of procedure and causes blemishes in the finished tube, it being understood of course that the side of the tube that contacts with the poleis inverted and becomes the outside of the finished vulcanized article. Still further, the fabricvalve base is usually apertured all or part way through, before being applied to the pole and covered by coils of greenstock, and duly ing the cure this pre-formed aperture is closed by "the flow of the rubber, which is under more or less pressure by an enveloping cross-wrapper, consisting of a strip of fabric coiled splrally under more or less tension about the green tube on the pole. This fill- I ing or" the hole, of course, rendered'it necessary to unch the tubeafter it had been cured. unchingrequired a strip of Wood or soft metal tobe inserted in the tube to prevent the punch going through both of its walls and necessitated an operation, adding to the cost of production. It the reinic'orc ing valve base is applied to the outside joi" the coiled green tube, it is difficult, after curing, to locate the punch so as to make the hole in the exactcenter of the base, which is invisible, or substantially so. According the old methods or procedures therefor, Whether the patch is located so as to come to the inside or to the outside of the finished tube, an operative could not quickly and reliably punch holes through the exact ,cen-

ter ofthe valve base. And still further, the

pressure otthe patch tends to flatten the stratum of rubber adjacent'the inserted anvil so that, after punching, the rubber stra tum contracts and becomes smaller in diameter than the hole through the fabric portion of the valve base. Consequently, a punch was used of a size making a hole in the fabriov reinforcement slightly larger than necessary. And this is obviously objectionable.

The present invention aims to produce a; new and improved tube in which the valve opening is molded therein during the. cure and preferably in the centerof aifabr ic reinforcing valve base that is vulcanized in the walls of the tube and substantially, it not completely, vconcealed from view. The

invention also aims to permit molding thea valve opening in the tube during its manufacture in a practical and economic inanner, ,elnninat ng the punching operation heretofore deemed necessary and theobjections, consequent punching.

applied thereto and with a hole-molding member in position, parts being spaced and enlarged for the sake ofclearness.

Fig. 5 illustrates the cured and finished tubeona pole and in cross section through the valve stem opening;.

Fig. 6 is a section similar to Fig. 5, to one .side of the valve stem opening;

Figs. 7 and 8 illustrate steps in a modified procedure.

, Usually in making inner tubes, a calendered sheet 1 of suitable vulcanizable rubber composition is laid on the tableand a pole A preferred embodiment of the inventionis illustrated in the accompanying drawings in which 2 placed thereon parallel with one side and rolled over the sheet so as to ply it up into a tube, the latter being indicated at 3.

The reinforcing valve base may be made in any suitable manner but, as shown in Fig. 3, is preferably made of a suitable number of plies of woven fabric l and vulcanizable rubber composition l of successively varied size, these plies being super-posed upon one another in the manner illustrated. Then preferably, the valve base, indicated generally by the numeral 5, is apertured centrally as indicated at 6. 1

According to the invention, and referring for the present to Figs. 1 to 5, the preferred procedure is to apply the valve base 5 to the outside of the formed tube 3 and with the largest ply of the base outermost as indicated in Fig. 4.

The next step in the preferred procedure is to insertahole-forming or molding member Tin the aperture6 in the valve base, the

member 7 having preferably a sleeve or barrel portion 8 and a flange or abutment portion 9; i

Then the green tube is cross-wrapped, i. e., it iscompletely confined in over-lapping spiral convolutions of a strip of fabric applied under more or less tension.

The tube thus prepared for curing is introduced in a steam heater, or otherwise treated, to completely vulcanize it. During the cure, the rubber softens and the holeforming-member 7 is projected therethrough. Preferably, but not necessarily, the holeforming-member 7 1s provided with a bevelled cutting" edge 8 for facilitating its movement through the stock.

After curing,the wrapper is removed and likewisealso the member '3'. Then the'cured tube is stripped from the pole, its ends spliced together, and a valve mounted in the opening that has been molded in the tube,

all in a manner well-known to those skilled in the art.

In the foregoing, the preferred method of procedure has been outlined. By locating the fabric valve base so that it is located on the inside, or at least nearer the in'sidethan the outside, of the finished tube, there is less likelihood of the product being blemished and the reinforcing or stiffening fabric 4 is disposed more advantageously. By mold ing the hole for the valve stem, not only is the necessity of punching the tube avoided, but the walls in the opening 6 aresmoother and the cut edges ofthe'fabric better pro tected. It may be noted that the short plug of rubber that lies, or forms, within the'barrel 8 may be readily removed on withdrawing the member 7. i I

The method of procedure may be varied in detail without departing from the prin ciples of the invention. lVhile not as desirable, the patch 5 might be applied to the pole directly and covered over by coiling the tube stock thereabout as has been the practice. In such case, with a little more time and care, the hole-forming-member 7 might be located in alignment with the hole 6 in the base and projected through the stock during the cure by the action of the wrapper as before described. But this is obviously not as desirable as the preferred procedure described. Alternatively also, the patch might be incorporated between convolutions of the green tube stock as illustrated in Fig. 7, and the hole-formingi member 7 positioned and projected through the layer of rubber over-lying-the'aperture in the valve base so as to imbed itselfin the underlying convolutions of green stock; this case also, when the wrapper is plied under tension and the tubeis intro} duced into a heater, there willbe substantially the same molding action asoccur"s in the preferred procedure that has been de scribed in detail.

The form of the hole-forming-member may be varied. F or instance, as shown in Figs. 7 and 8, it may be a disk or plug 10. lfn this form, afterv plying up the green rubber sheet on the pole with thereinfor'c ing valve base preferably but notnecess'a rily intermediate convolutions thereof, the hole- :lorming-inember 10 may be pressed upon the outlying thin layer or layers' of rubber covering the hole 6 and in sucha way astto" carry the same against the underlying. can volutions of green stock, as diagrammati cally illustrated in Fig. 7 The cured prod: not, before removal of the hole moldingmember 10, is illustrated in Fig. SITh thin layer, or film, of vulcanized rubber 11 underlying the -member 10 (wh'i ch may be made very thin by increasing the thickness of the plug 10) may be p'ressed out" in the' removal of the member 10, or cut or -brokeh as "desired (with the introduction ofth' valve stem, for instance).

These and other changes in the details of the invention are contemplated and refeii ence should, therefore, be made to theap a tube fromvulcanizable rubber composi tion, rolling a sheet of vulcani z able rubber composition about a pole, making a laminated reinforcing valve-base' of superposed plies of fabric successively varied insiie to form a skived margin, aperturing the reinforcing valve-base centrally, securing the reinforcing valve base to. the formed composition tube with'itswidest ply outer? most, introducing a' flanged sleeve" inthe opening in the reinforcing valve-base and holding it in place, curing the tube thus formed, removing the flanged sleeve and splicing the ends of the tube.

2. A method of manufacturing inner tubes for pneumatic. tires which consists in sheathing a pole with vulcanizable rubber composition, applying a reinforcing Valvebase to the exterior of the composition tube,

10 inserting a hole-forming-member in the tube through the center of the reinforcing valvebase, confining the tube and hole-formingmember, vulcanlzing the tube, removing the tube from the pole and turning it inside out, splicing the ends of the tube, and finally mounting a valve in the hole thus formed therein. 1 I

Signed at Indianapolis, this 31st day of August, 1921.

RALPH E. STEPHENSON.

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