Fig. 2898.
[Figs. 2897] and [2898] represent an example of welding a collar on round iron. The bar is upset so as to enlarge it at a, where the collar is to be. The collar is left open at the joint, and while it is cold it is placed on the red-hot bar and swaged until the ends are closed. The welding of the whole may then be done at one heat, swaging the outside of the collar first. Unless the bar is upset there would be a crack in the neck b of the collar on both sides.
Welding Angle Iron.—Let it be required to form a piece of straight angle iron to a right angle.
Fig. 2899.
The first operation is to cut out the frog, leaving the piece as shown in [Fig. 2899]; the width at the mouth a of the frog being 3⁄4 inch to every inch of breadth measured inside the flange as at b.
The edges of the frog are then scarfed and the piece bent to an acute angle; but in this operation it is necessary to keep the scarfs quite clean and not to bend them into position to weld until they are ready for the welding heat; otherwise scale will form where the scarfs overlap and the weld will not be sound.
The heat should be confined as closely as possible to the parts to be welded; otherwise the iron will scale and become reduced below its proper thickness.