Hardening, tempering, annealing and forging of steel; a treatise on the practical treatment and working of high and low grade steel .. . black before thehardening heat this uneven contraction is to a certain extent pro-vided for. In hardening a die the quenching of it so that the frailest por-tion enters the bath first and hardens before the thickest por-tion, will most invariably cause cracks to appear, as unequal con-traction takes place and the heavy portion contracting the most,changes shape in attempting to draw with it the frailer cause of cracks in dies is the use of im
Hardening, tempering, annealing and forging of steel; a treatise on the practical treatment and working of high and low grade steel .. . black before thehardening heat this uneven contraction is to a certain extent pro-vided for. In hardening a die the quenching of it so that the frailest por-tion enters the bath first and hardens before the thickest por-tion, will most invariably cause cracks to appear, as unequal con-traction takes place and the heavy portion contracting the most,changes shape in attempting to draw with it the frailer cause of cracks in dies is the use of improper meansfor grinding. When a die is ground on a machine on whichno provision is made for water cooling, or where a fine wheel isused, cracks often result, coming about through the steel beingunevenly heated during the grinding. Thus, by using a coarse THE HARDENING AND TEMPERING OF DIES. 169 wheel with a free water supply this disagreeable possibility willbe eliminated. Hardening the Walls of a Round , in die work, it is desired that the walls of a drawingdie, for instance, or some other part, such as the inside of a. FIG. 120.—BIvANKING DIE). hollow punch, should be hard and the remaining portion of thepiece soft. This may be accomplished by proceeding as follows:Clamp the die or punch, as the case may be, between flanges on 170 HARDENING, TEMPERING AND ANNEALING. the ends of tubes, being sure to have the steel at the proper allow a stream of cold water or brine to circulate throughthe tube and the metal will harden in depth as far as the insideedges of the flanges while the remaining portion will remain soft. Reannealing a Punch or Die a piece of steel, which is to be used for a punch
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Keywords: ., bookcentury1900, bookdecade1900, bookidhardeningtem, bookyear1903
