746 



THE INDIA RUBBER WORLD 



July 1, 1921 



New Machines and Appliances 



STANDARD TIRE CALENDERS 



STANDARD Calenders employed in the tire-manufacturing in- 

 dustry are massive machines of the 24 by 66-inch, 3-roll 

 type, equipped with electric motor-drive and control. Tire 

 calenders are operated on "friction" by variation in the relative 

 speeds of the middle and bottom rolls whereby the fabric structure 

 is filled with rubber, or on "even motion," that is, with rolls 

 revolving at the same speed producing a smooth sheet of rubber 

 which may be directly applied as a "skim" coating on fabric 



rear of the machine and passes through the calender between the 

 middle and bottom rolls. These rolls are adjusted w-ith suitable 

 interval between, to "bank" the rubber against the bottom roll. 

 It is this revolving bank of rubber which forces the rubber into 

 the fabric as it passes. The first friction coat practically goes 

 entirely through the weave of the fabric and, therefore, com- 

 prises more than half the rubber applied to a fabric frictioned on 

 both sides. After each passage through tlie calender the goods 

 are rolled on a stock-shell set in the "take-up" device on the 



" ^f: 



BIRMINGHAM 



VAUGHN 



ADAMSON 



WELLMAN -SEAVEt?- MORGAN CO, 



Standard Types of 24 by 66-Inch 3-Roll Tire Calenders 



already "frictioned" or delivered of thicker gage for independent 

 use for inner tubes, side-walls, etc. 



Preliminary to the calendering operation the rubber compound 

 is wanned up on a mill and the calender rolls are heated to a 

 temperature suitable for the compound which is then fed into 

 ihc calender between the top and middle rolls. The feed-slide is 

 known as the front of the calender. 



front of the machine. When coating the second side, it is nec- 

 essary to wind the double-coated fabric in a liner of plain cotton 

 sheeting to separate the tacky rubber surfaces and prevent their 

 adhering and making the roll solid. 



In friction-coating, the surface speed of the bottom roll is 

 about 30 per cent slower than that of the middle or drive-roll 

 to gain difference in speed for the frictioning effect. 



FRICTIONING FABRICS 



The term "frictioning" designates the process of impregnating 

 a fabric by filling its meshes from one or both sides with rubber 

 or composition. This effect results from a variation in the 

 relative speeds of the middle and bottom rolls by which the 

 rubber on the middle roll is made to revolve as a "bank" against 

 the surface of the fabric passing through at the siieed of the 

 bottom roll. This difference in siKcd forces the rubber through 

 the meshes of the fabric while the surface of the goods also 

 gains a light coating of rubber. 



The operation of frictioning is conducted as follows : The 

 middle or drive roll is covered with a heavy coating of warmed 

 rubber. A roll of fabric is placed in the brake-bracket's at the 



SKIM-COATING AND SHEETING 



Skimming consists of laying a very thin coat or sheet of rubber 

 on one side of the frictioned fabric to give it a smooth finish and 

 build it up to a specified gage or thickness. This is done by 

 passing the frictioned fabric through the calender between the 

 middle and bottom rolls as for friction coating. In skim coating 

 the speeds of all the rolls are the same. This condition is desig- 

 nated as "even motion." Thus arranged a calender will produce 

 smooth rubber sheets of any desired thickness according to 

 adjustment apart of the middle and bottom rolls. Arranged on 

 even motion a calender is ready for building up to specified gage 

 pure rubber for inner-tubes, side-walls or any other purpose re- 

 quiring a smooth sheet. 



