374 



THE INDIA RUBBER WORLD 



[July 1, 1911. 



RUBBER ROLLS OF MANY SORTS. 



nPHE use of rubber-covered rolls has long been an important 

 *■ factor ill almost all trades, new uses being constantly found 

 for them. Long ago they displaced rolls formerly covered with 

 leather, felt and other substances. For gripping and feed rolls, 

 rubber is the standard covering everywhere, owing to the fric- 

 tional surface that it gives. It also finds a considerable use as 

 a substitute for cog wheels in transmitting light power. The 

 same principle is familiar to all in the rubber tire, which is 

 really a rubber roll, and which transmits power to the ground. 

 Owing to reduplicated friction, one rubber-covered roll will 

 transmit its power to another much more efiiciently than to the 

 ground. There are many kinds of light machinery in which 

 counter-working rubber wheels could be used, thereby doing 

 away with the necessity of a separate clutch. 



While the ordinary rubber tire is but one form of rubber roll, 

 it has won such prominence as to eclipse all other forms put to- 

 gether, and now forms a class by itself. Under rubber rolls 

 should come every rubber-covered wheel which runs upon the 

 floor or ground, including roller skates, table leg castors and 

 the like. 



Among power rolls, the largest use is in paper and leather 

 working machines. They are also extensively used to wring or 

 squeeze the water out of various materials, such as cloth in 

 bleacheries, dye and print works, cotton, woolen, felt and 

 shoddy mills, in making oiled clothing and in wool scouring. 

 In glucose and sugar factories, the sugar sacks and blankets, 

 through which the syrup is strained, are steeped in water and 

 run through power wringers, to save the sugar that is in them. 

 In tobacco factories the leaves, after being steeped in the flavor- 

 ing syrups, are run through wringers to remove the e-xcess of 

 liquor. During the last two or three years, rubber rolls have 

 rapidly supplanted leather rolls in lithographic work, with sev- 

 eral distinct advantages in their favor. The rolls are perfectly 

 true, less color is used, and much time is saved in washing up. 

 The use of rubber inking rollers is being extended to various 

 other kinds of printing, such as stamping tin and sheet iron. 

 Other uses are arising day by day, rolls for such purposes being 

 made to order. In fact, except in clothes wringers and type- 

 writer rolls, most of the business in mechanical rolls is done to 

 special order, because of the lack of standardization in most 

 rubber roll using machines. 



The clothes wTinger, which depends upon rubber rolls, is an 

 American industry from first to last, having developed from small 

 beginnings some fifty years ago. Nowadays the larger part 

 of the business is done by the American Wringer Co. Their 

 output is some 6,000 rolls a day, with a capacity of 10,000. The 

 company have made their own rolls for some fifteen years, and 

 their rubber factory is quite extensive. 



The greatest problem met with in the making of rubber rolls 

 has been to secure such adhesion to the shaft, that the rubber 

 will not twist oflf under the severe strain to which they are sub- 

 jected. Mr, George H. Hood originated, or rather revived, the 

 method of vulcanizing rubber to iron, through the medium of 

 copper plating, which combined with the sulphur during vul- 

 caniz^ation, thus securing perfect adhesion between the two 

 bodies. He applied this method of fastening to both rubber 

 rolls and rubber tires, which, as we have shown, present simi- 

 lar characteristics and problems. Hood's method is still used, 

 in a modified way. Instead of copper plating the shaft, on 

 which the rubber is to be built up, it is first painted with 

 metallic salts which accomplishes the same purpose in securing 

 adhesion of the rubber to the iron. The sheet rubber is then 

 wrapped around the shaft to the desired thickness, the first 

 wrapping being a sheet of hard curing rubber. Sometimes there 

 are three different layers of rubber, hard at the shaft, then a 

 layer of semi-vulcanite, with the outer layer of soft rubber. 



This method is troublesome, but it adds greatly to the life of the 

 roll. 



When the whole shaft has been built up to the desired thick- 

 ness it is wrapped, vulcanized and ground true on a lathe. 

 Molds are not much used now, better results being obtained by 

 wrapping and curing the built-up roll. It was formerly the cus- 

 tom to cure the roll on a mandrel. The shaft was then painted 

 with rubber solution, wrapped with twine, solutioncd again, and 

 the rubber tube forced over the shaft. This method has been en- 

 tirely superseded by the one described above. 



In a former issue of The India Rubber World there was de- 

 scribed a much cheaper method of making wringer rolls. The 

 rubber cover is spewed out of a tubing machine to any length 

 desired, of smaller diameter than the shaft or rod. The rod is 

 then heated and forced through the tube, the heat in the rod 

 causing the rubber to vulcanize so firmly to the iron that it can- 

 not be torn loose. If the heat from the rod does not continue 

 long enough to get the best results, it might be kept warm by 

 means of an electric current. 



The typewriter uses considerable rubber, though far less 

 than the wringer. AH typewriters have rubber feed rolls, and 

 most have a rubber-covered platen, against which the type 

 strike. It was this platen, the patent for which was owned by 

 the Remington Co., that first made the typewriter a commercial 

 proposition. It was formerly made much larger and of almost 

 solid rubber; but it is now only a hollow wooden core, with a 

 skin of rubber about one-eighth inch thick over it. The degree 

 of softness, which this rubber coating should possess, is im- 

 portant. For rapid work it should be as springy as possible, 

 while a hard surface is best for manifolding. When first 

 turned out the platen rubber is soft, hardening after a few 

 months' exposure to the air. The feed rolls were formerly made 

 of wood, with a few rubber bands stretched over them, but these 

 are always made of rubber now. 



Like the wringer, the typewriter is an American institution 

 and over 90 per cent, of the world's typewriters are made in the 

 United States. The export trade in tj'pewriters amounted for 

 the fiscal year ending June 30, 1909, to $6,899,069, for the same 

 period ending 1910 to $8,239,510, and for the first 9 months of 

 the fiscal year ending June 30, 1911, to $6,917,174. Great Britian is 

 our best customer for typewriters, the value of the exports to that 

 country amounting to nearly $2,000,000 a year, Germany comes 

 second, with purchases of about half that amount. The English 

 makers have not thus far been able to turn out a first-class ma- 

 chine, though they have tried to imitate some of the American 

 machines exactly, part for part. 



No one rubber company has a monopoly in making typewriter 

 rolls, but these are supplied by all of the great rubber concerns. 

 There are no particular problems connected with their manufac- 

 ture, though the platens must be accurately trued. The type has 

 no great effect upon the platen, but the punctuation marks grad- 

 ually dig groves in it, necessitatitig a new rubber covering. In 

 fact, any rubber roll may be recovered, in whole or in part, and 

 the repair business is becoming an important branch of the 

 trade. 



As nearly as can be estimated, about 1,500,000 typewriters have 

 been made and sold by .\merican companies. Figuring renewals 

 of old rolls, which occurs on an average about once a year, and 

 rolls for new machines, the business for typewriter manufactur- 

 ers, must amount to considerably over a million rolls a year. 



MADE OF GNU RUBBER. 



Not O'Sullivan's "new rubber," but short pieces of garden 

 hose, is what the horns of the fighting Gnus at the New York 

 Zoo are equipped with. They still fight, but ineffectively, and 

 rubber has scored another triumph. 



Replete with information for rubber manufacturers: Mr. 

 Pearson's "Crude Rubber and Compounding Ingredient.':." 



