79C 



THE INDIA RUBBER WORLD 



[September 1, 1920. 



Tire 



Bead Manufacture. 



Kellc 



Hx R. 



T IS an old axiom among nil)l)er men that their niercliandise 

 I is only as good as its weakest part; thus, the tiny piu- 

 *■ hole makes the whole inner tube useless, and the started 

 sole makes the rubber shoe a second. This is particularly 

 true of the automobile tire — a tough tread with a good non- 

 skid design, the best Sea Island cotton frictioned with 95 

 per cent Para, and a strong side wall will not give the mileage 

 if the bead construction is faulty. 



Bead making, while not involving any complicated proc- 

 esses or highly skilled workmanship, is nevertheless of 

 enough importance to warrant .i se])rirate (leii.irtnieiit for 

 this work. Beads 

 are divided into 

 two classes, the 

 straight - side 

 bead and the 

 clincher bead 

 for demountable 



MAKING 



STRAIGHT-SIDE 



BEADS. 



The straight- 

 side bead is built 

 up on a wheel 

 the size of tlie 

 tire, as here 

 illustrated. This 

 makes it neces- 

 sary to have as 

 part of the 

 equipment a 

 wheel w h i c li 

 can be used in- 

 terchangeably 

 on the bead 

 making machine 

 for each size of 

 tire. This wheel 

 has the outer 

 edge raised, 

 forming a . 

 groove in which 

 the bead is 

 constructed in 

 the following 

 manner: first, a 

 strip of fric- 

 tioned cloth 



about two or three inches wide, cut on the bias, is laid in the 

 groove and stitched down with a plain hand stitcher or re- 

 volving wheel. Then several coats of cement are applied 

 with a brush, and the strands of wire placed in the strip, 

 twice around the wheel. On top of this as a covering are 

 laid two plies of bead cord which comes in strips similar 

 to cord fabric only of smaller staple cotton. The parts are 

 then rolled together firmly by pressure of a hand roller on 

 the revolving wheel. 



The final operation before curing is to fold over the plies 

 of fabric, completely covering the wire which is embedded in 

 the center of the fabric. Great care must be taken to see 

 that the wire is covered at all points, otherwise it will break 

 through in the cure and spoil the bead. Spoiled or damaged 

 bep.ds are a total loss, as their hard, brittle texture and the 

 presence of the wire make them valueless for reclaiming 



.-/. B. 



purposes. In tire reclaiming one of the first operations is to 

 cut out the bead. 



The bead is cured in a circular mold in a hydraulic press 

 for about seven to ten minutes and comes out in the form of 

 a hoop. The overflow is trimmed ofif on a trimming machine, 

 shown in the picture, and the beads are then inspected for 

 breaks and defects due to faulty stock, poor making, curing, 

 or trimming. Before passing to the tire maker the beads 

 are dipped in a vat of specially prepared cement and hung 

 iiu racks to dry, as here illustrated. This is to give the bead 

 plent}- of adhesion so that it will stick well to the plies of 



fabric which en- 

 compass it in 

 the tire. 



The bead now 

 passes to the 

 tire maker and 

 is built into the 

 tire as follows: 

 the maker first 

 idaces the iron 

 core on his ma- 

 cliine and starts 

 the first ply of 

 building fabric 

 '111 the core in 

 ^uch a manner 

 I hat it entirely 

 covers it, the 

 center line of 

 ply following 

 the center line 

 of the core, al- 

 lowing it to 

 iiverlap the core 

 evenly on both 

 sides and ap- 

 Iilied with equal 

 tension. He next 

 manipulates the 

 two mechanical 

 stitchers, bend- 

 ing the plies in- 

 to the under 

 side of the core, 

 forming ears in 

 which the bead 

 is placed within 

 iron rings, which 

 are held in place by clamps. The picture shows a tire-maker 

 placing the bead for a straight-side tire. The bead in posi- 

 tion, the rings are removed and the bead thoroughly stitched 

 down to secure proper and uniform adhesion. The bead is 

 covered by a piece of friction known as the bead ply or rein- 

 forcement and encompassed by additional plies of fabric. 

 MAKING CLINCHER BEADS. 

 The clincher bead differs from the straight-side bead in 

 that it has a core of hard rubber instead of wire and is more 

 nearly circular in shape, whereas the straight-side bead is 

 like a triangle with sharp edges. This core is mixed and 

 compounded with a high percentage of sulphur to make it 

 vulcanize hard. 



The stock is warmed up and run either on an outsole cal- 

 ender with a roll specially engraved for this purpose or on 

 a tubing machine. These long strips of uncured bead gum 



kTMt 



