722 



THE INDIA RUBBER WORLD 



fAucasT 1, 1920. 



piece of chalk and then cutting to size with a knife. When tin- 

 foil is used these sheets can be stacked but when it is not used, 

 trays or books with several sheets of holland must be used. 



A gang of six men work at a table shown in Fig, 4, with 

 wooden tops A and a steam-table B which carries approximately 

 eighty pounds' pressure. These men 

 make up the jars and remove them 

 from the cores after they are cured. 

 I-"or this work they get from five dol- 

 lars to eleven dollars per 100 jars, de- 

 pending on the make and size. One 

 of these men is called the leader and 

 is directly responsible for the men 

 and for defective jars made by his 

 gang. The steam-table is used to warm 

 up the cores and stock. When the core 

 is warm, it gets a coat of silicate of 

 soda which dries very quickly. This 

 solution prevents the finished jar from 

 sticking to the core and facilitates its 

 removal from the core. 



The ribs are then assembled in the 

 core cavities as indicated in Fig. S. 

 They are inserted (See A) and pressed 

 down with the knife handle used for 

 trimming; the trimmed rib is shown at 

 B. These ribs are made from a dry 

 stock, mostly hard rubber dust and 

 shoddy, and soap-stoned so that they 

 will not stick to the core. After the 

 ribs are trimmed, the bottom and ribs 

 are coated with cement and placed on 

 a piece of rubber which forms the 

 bottom of the jar. The core is then 

 turned over as shown in Fig. 6 and the rubber is trimmed with 

 the knife B using the core as a guide. The sides are then 

 cemented so that the rubber will stick to the core. 



The sides are next wrapped as shown in Fig. 7 and the rubber 

 sheet A trimmed at B. By pressing the knife handle along the 

 edge B the impression shows where the stock meets. Using this 

 impression as a guide, the surplus stock is trimmed ofif and the 

 sides are then rolled down to press out any trapped air between 

 the core and walls. This is done with a steel rolling pin, weigh- 

 ing about fifteen to twenty pounds. 



The top is next trimmed as shown in Fig. 8, using knife B and 

 a wooden block A, which is the correct height. A hard rubber 

 block as shown at C is then inserted, the thickness of which 

 allows enough rubber to be turned over on the bottom after 

 trimming with the knife D. The edges are then turned in as shown 

 in Fig. 9, working from both ends, first at A and then B, when 

 the reinforcing strips are assembled as shown in Fig. 10 at A. 

 The identification of the customer and the gang number are 

 then stamped on the jars which are stacked on small heater 

 trucks, care being taken that they do not touch each other, and 

 they are vulcanized from four to four and one-half hours at 

 approximately fifty-five pounds pressure. 



Some manufacturers have designed and built machines for 

 wrapping battery jars mechanically, but these machines, although 

 doing a better job than the hand method, do not materially 

 increase production over the manual method. 



After removing the jars from the heaters, the tin-foil is imme- 

 diately removed because if it is left on, the jars take a brownish 

 color. After cooling in the air between five and ten minutes, 

 the jars are partly stripped from the cores. This is so that the 

 jars will not warp or shrink by giving them time to set. If 

 battery jars become set on the cores it is very difficult to remove 

 them without frequent breakage and damage to the core. There 



are several methods of removing jars from cores and some are 

 by rather mgenious mechanical devices. The simplest is a hand 

 method m which a tool similar to ice tongs is used, only that 

 nistead of sharp points on the ends, they have two parallel bars. 

 With this method fewer jars are broken in removing them. 



After fifteen minutes the jars are completely removed from 

 the cores and piled neatly on the floor until they are completely 

 cooled. The bottom and top of the jars are then ground to a 

 finished dimension as specified by customers. This is done on 

 either disk or belt grinders. The belt grinders are used mostly 

 for smoothing up the jar seams. The bottom is ground first 

 and held to a close limit in relation to the inside ribs. These 

 ribs are important as they hold up the positive and negative 

 plates with the separators, and the sediment created by the acid 

 drops to the bottom, thereby eliminating short circuiting of the 

 battery. The tops are then groiuid square with bottom and the 

 seams touched up on a belt grinder, when the jars are ready 

 for the electrical test. 



Battery jars are given an electrical test of 18,000 to 30,000 

 volts as specified by the customer. At one time a water test 

 was made by sealing up the jar and putting it under approxi- 

 mately 4 pounds' pressure. This test has long been disregarded. 

 The following elongation and tensile strength test and standard 

 test piece was adopted August 27, 1918, by the Hard Rubber 

 Division of the War Service Committee : 



ELONGATION AND TENSILE STRENGTH. 

 The elongation is to be based on a 3-inch measured test sec- 

 tion. Measurement must be made before test sample is put into 

 the testing machine. Either dividers or extensometers applied 

 to the test piece at the ends of the measured length may be used 

 to measure elongation. The dividers or extensometers used in 

 measuring the elongation must be free from, and independent of, 

 the testing machine or any movement of the heads. 

 The tension test is to be made in a Tinius Olsen, or similar 

 testing machine of suitable capacity. 

 The rate of speed of the separation of 

 jaws shall be uniform and shall be 

 between 1/10-inch and 2/10-inch per 

 minute. The test pieces before break- 

 ing shall be immersed in water for one 

 hour at a temperature of 70 degrees F. 

 Battery jar test pieces are to be broken 

 in testing machine room temperature 

 of between 70 and 80 degrees. 



CLAIMS rOR REHEARING. 



Rejected material and samples of it 

 will be held for one month from date 

 of test report. .Accordingly, in case of 

 dissatisfaction with the result of test, 

 the shippers must make claims for re- 

 hearing, should they desire it, within 

 that time. Upon application for re- 

 hearing, the shipper may send a repre- 

 sentative who may sort the rejected 

 jars, accept as rejected such jars as he 

 desires, and submit for further test 

 the balance claimed within the specifi- 

 cation. Such balance shall be tested in 

 the presence of the shipper's represen- 

 tative, the samples being paid for by 

 the shipper. 



For such retest five jarj shall be se- 

 lected at random from each thousand, 

 or from each lot, and should the aver- 

 age of test meet the specifications, the lot tested shall be ac- 

 cepted. This does not apply to individual rejections. 



After passing the various tests the jars are ready for shipment. 



