168 NOTES ON CHAIN CABLES. 



A scarf of desirable form was finally obtained by further forging the ends of 

 the bolt under a drop hammer with dies, as shown in Fig. 23, Plate 100. The bolt 

 as it comes from these dies is shown in Fig. 23 A, Plate 100. This work is accom- 

 plished in the same heat as used for upsetting and bending the ends. The ends are 

 now of the proper form, and if thrown together may be placed in welding dies with- 

 out working and will give a link of correct form. 



The scores in the upper die and the ridges formed thereby on the scarf are for 

 the purpose of assisting the weld. As some difficulty was experienced in obtain- 

 ing good welds, it was thought possible that the upsetting and scarfing operations 

 increased the density of the material in the ends, made it hard and difficult to weld 

 and further that the chilling effect of the scarfing dies produced a hard surface or 

 case over the scarf which the heat could not penetrate nor soften. The scores 

 were placed in the die to break up the hard surface and destroy the continuity of 

 the surface fibers. The eft'ect has been to produce better welds. 



The ends of the link having been formed with slight reinforcement at the 

 quarters and with convex scarf, it is now necessary to provide for closing the two 

 ends together and reeving into the previous link. 



This was first attempted by winding the link on a spiral mandrel, leaving an 

 opening between the scarfs sufficient to permit of reeving into the previous link. 

 This method was open to the objection that the link was twisted out of plane and 

 was difficult to restore to proper form; and, further, that in winding, the link 

 twisted about the longitudinal axis of the bolt and threw the scarfs out of parallel. 

 As this did not always occur to the same extent it was difficult to allow for. 



The method finally adopted was to reeve through the previous link and then 

 wind on a flat mandrel slotted out to accommodate the previous link as shown in 

 Figs. 24, 25, Plate loi. Figure 26, Plate 102, shows the winding completed and 

 the scarfs laid together. The increased thickness through the portion to be welded 

 should be noted. This experimental winding machine was designed to operate by 

 hand so that it could be moved from place to place in connection with experiments 

 performed in the vicinity of fixed machines. As a final proposition it would, of 

 course, be designed to operate by power. 



Welding. — With machine-welded chain the welds are made in dies under a 

 hammer, usually a helve hammer. Two forms are used: 



(i) The helve hammer with the trunnions about on the level of the anvil, 

 striking a blow directly down, actuated by a cam, and employing a cup die. This 

 type is very fast in operation and is used on the cheapest work. 



(2) The helve hammer with the trunnions below the level of the anvil, striking 

 a blow with a slight forward movement, actuated by a slotted lever from a crank- 

 shaft overhead, lifting the hammer against the tension of a spring and employing a 

 die which is the reverse of the cup die, in that the cup die is on top and the pin die 

 on the bottom, the cross-section being as shown in Fig. 27, Plate 99. This is known 

 as the Standish hammer and die and is the favorite type among machine chain- 

 makers, being a little slower than type i, but making a better quality of chain. A 

 photograph of this type is shown in Fig. 28, Plate 102. 



