THE INDIA RUBBER WORLD 



473 



Welding Rims by Electricity 



By C. D. Ryder.* 



IN the older days of rim manufacture the processes used were 

 more or less crude as compared to present day methods. This 

 is a general statement that may be applied equally well to 

 many industries, and the manufacture of automobile rims is no 

 exception to the rule. Inasmuch as this article is supposed to 

 deal chiefly with the process of welding rims rather than to con- 

 \'ty a great deal of information regarding the whole process of 

 manufacture, the writer will try to give a clear idea of this work, 

 the result of observations made in a number of the larger plants, 

 and of experience covering several years' intimate connection with 

 the electrical welding process. 



The old original, tinie-lionored method of welding iron or steel 

 involved taking the articles to be welded to the blacksmith shop. 



Fig. 



-17A Electric Welder. 



which was a distinct and important department in every well 

 regulated factory. The pieces to be welded having been delivered 

 to his "sanctum," the blacksmith proceeded to heat the ends and 

 scarf them down by hammering. He then placed the ends again 

 in the tire, sprinkling a little borax and sand over them to reduce 

 oxidation, and brought them up to the welding heat. Upon at- 

 taining the correct temperature, the pieces were withdrawn, the 

 ends overlapped, as provided by the scarf, and the joint hammered 

 to force the two ends of metal together forming a weld. The 

 hammering was continued until the metal at the joint was re- 

 duced to about the same dimensions as the original stock. 

 Obviously this method was slow and productive of uncertain re- 

 sults. The strength of a weld made in this way depended 

 altogether on the skill of the blacksmith. It may be said that 

 no matter how skilful the blacksmith or how carefully the joint 

 was made, it could not by any possibility approach very closely 

 the strength of the original stock. The chief reason for this lay in 

 the fact that more or less oxidation takes place in spite of the flux 

 used, which was retained in the weld at the junction of the pieces. 



However crude and unsatisfactory the old method may have 

 been, it was the only one which could be used until the advent 

 of the electric welding machine. As a matter of fact, it may be 

 conservatively stated that the electric welding machine has made 

 possible the successful production of automobile wheel rims on 

 a commercial scale. Electric welding is now done, exclusively, in 

 every rim plant in the United States, so far as the writer knows. 



•Electrical Engineer. The Toledo Electric Welder Co., Cincinnati. Ohio. 



Just here it may be of interest to explain, briefly, what an electric 

 welder is, how it operates and the kind of welds it produces. 



Fundamentally, the electric welder depends for its operation 

 upon a well-known law which states that if an electric current 

 is caused to pass through a substance (such as iron or steel) a 

 certain amount of heat will be developed in tlie substance 

 traversed by the current which will be proportional to the square 

 of the current, the resistance the substance offers to the flow of 

 current, and to the time the current is applied. The final tempera- 

 ture attained by the substance will depend upon the readiness 

 with which this heat is dissipated by radiation and conduction. 

 An electric welder, then, is a machine for securely c..:v.iping 

 the parts to be welded in proper alignment, with means for pass- 

 ing a heavy electric current through the abutting ends of metal 

 and with provision for forcing these two ends together to com- 

 plete the welding operation. The commercial machine is one 

 which not only embodies these three essential features but, in 

 addition, is equipped with means for adjusting the current 

 through a given range of values, to suit the stock to be welded^ 

 switching mechanism for applying and turning off the current, 

 and numerous adjustments which are obviously necessary. 



Little or no preparation of the stock is required for performing 

 an electric weld. All that is necessary is to have the surfaces 

 fairly clean, to insure good electrical contact of the material in 

 the copper dies or electrodes. No scarfing of the ends is done. 

 The heat is developed at the junction of the abutting ends only. 

 When the correct welding temperature is reached, the current is 

 turned off and the ends are forced together by the action of a 

 lever or an hydraulic ram. In the process of forcing the ends to- 

 gether the burnt and oxidized metal is extruded from the weld in 

 the form of a fin, which is quite thin and is easily removed. As all 



Fig. 



-15 A Electric Welder. 



the burnt or oxidized metal is thus extruded, leaving only clean 

 metal which has not been touched by the air in final contact, no 

 flux is required and the joint is of maximum strength. Tests 

 made to determine the strength of a weld made in this manner 

 indicate that usually, barring carelessness, the welded portion will 

 show the same strength as any other portion of the stock of like 

 sectional area. 



Various methods are employed in the different large 

 plants in the manufacture of automobile rims, but the following 



