June 1, 1921 



THE INDIA RUBBER WORLD 



643 



Embossing Machines Used in Rubber Manufacture 



THE surface ornamentation of soft rubber goods is obtained 

 usually by engraved designs upon plates or molds into which 

 tlie rubber is forced during vulcanization. Goods that are 

 cured in beds of talc or in dry heat, however, have their surfaces 

 ornamented before vulcanization. This is accomplished as a rule 



MuLLER Cut Sheet Embossing Machine 



when the material is still in the sheet form and before it has 

 gone cither to the cutting or making-up departments. 



An example of this is cut sheet from which European tobacco 

 pouches and articles of that sort are made. The very beautiful 

 w-avy lines on the surface of cut sheet are simply knife marks 

 left in the cutting process which is analogous to the production 

 of wood veneers. It has often been the ambition of the manu- 

 facturers to imitate this by using engraved rolls in connection 

 with the calender, but the result is not good. 



Calendered sheet is, however, embossed by the Miiller machine 

 so that it looks like cut sheet. This machine is very simple and 



w 



Fleurs-de-Lis Water Mark Straight Line 



Hot-Water Bottle Embossing 



is operated either by hand or by power. It consists of two 

 fluted rolls the upper of which may be raised or lowered to ac- 

 commodate different thicknesses of stock which is passed once 

 through the rolls, and the wavy lines are permanently impressed 

 upon its surface. 



For water bottles, fountain syringes, dress shields and many 

 other ribbed stocks the old-fashioned way was to run the stock 

 on heavily ribbed cloth and trust to the impression thus given. 

 It was far from perfect and was later supplanted by the use of 

 vulcanized squares that were deeply ribbed. Sheets of stock were 

 placed upon these forming sheets and cold pressed for twenty- 

 four hours. They were then stripped and sent to the cutting 

 room. As this process was slow and expensive, it in turn was 

 supplanted by a grooved roll mounted on a frame and bolted 



fast to the calender bed plate. The roll is adjustable, with 

 screws at both ends, and if the embossed stock is to be dusted 

 when calendered, a dusting table is used. 



EMBOSSING CARRIAGE CLOTH 

 Rubber carriage cloth for covering the tops of automobiles, 

 as it comes from the calender, is of a dull dead black or brown 

 color, similar to the finish usually found on rubber blankets. 

 While this sort of fiijish is suitable for some work, most users 

 require cloth with a small raised design. The following four 

 styles of impressions are common : 



1. The pinhead pebble where the cloth looks as though it 

 were covered with pinheads about 1/32-inch apart. 



2. Long grain, which is popular with the automobile top manu- 

 facturers, looks as though scratched all over with the point of a 

 pin, no regular design being carried out. 



3. English grain. Here raised lines are about 1/16-inch wide 

 by 3/4-inch long, and all one way, but no two lines cross. 



Side Roll Embossing Calender with Dusting Table 



4. Flat grain, in w'hich the Ifnes are about 1/16-inch wide,. 

 very short and crooked, and are scattered over the cloth close 

 together and running in all directions. 



In order to give the cloth this finish it is run through an 

 embossing calender. 



THE STANDARD EMBOSSING CALENDER 



This machine usually has three rolls (sometimes two), set 

 horizontally. The middle or drive roll is of steel, 8 inches in 

 diameter by 60 inches long, and is engraved with the reverse 

 pattern desired on the surface of cloth. The top and bottom 

 rolls are of steel, covered with paper by hydraulic pressure, and 

 are twice the diameter of the middle engraved roll. The driving 



Cut Sheet Tobacco Pouch — Note Wavy Lines 



arrangement is the same as in any ordinary calender, with gears 

 on the. rolls to run them at even surface speed, as the engraving 

 on the 8-inch steel roll forms an impression on the paper rolls 



