Canadian machinery and metalworking (July-December 1917) . FIG. 2. tions are widely different. This is moreclearly indicated by referring to Fig. sketch to the left illustrates themethod of shearing metal, the stock be-ing severed by means of two blades, thecutting faces of which are in line witheach other. In the ordinary power shearthe lower of these two blades is sta-tionary, while the upper travels in avertical direction; the cutting edge ofthe blade being set at an angle to theone on the fixed table. In the case ofa punch and die, the two cutting edgesare often left parallel to each
Canadian machinery and metalworking (July-December 1917) . FIG. 2. tions are widely different. This is moreclearly indicated by referring to Fig. sketch to the left illustrates themethod of shearing metal, the stock be-ing severed by means of two blades, thecutting faces of which are in line witheach other. In the ordinary power shearthe lower of these two blades is sta-tionary, while the upper travels in avertical direction; the cutting edge ofthe blade being set at an angle to theone on the fixed table. In the case ofa punch and die, the two cutting edgesare often left parallel to each other, butshear may be given to one or the otherby scolloping the cutting edges. Com-paring this shearing of metal to theaction of the ordinary cutting tool, as. FIG. 3. used on a lathe or planer, we immedi-ately comprehend the varied center sketch of Fig. 1 shows alathe tool set to two different depths ofcut, which according to the shearing in the left hand sketch. The detail thatmay be said to relate these two pro-cesses, shearing and cutting, is the com-pression of the material as the cut is be-ing made. When a piece of material hasbeen sheared the ends will have the ap-pearance shown at A and B, where themetal has been squeezed during the ini-tial stages of the cutting process. Thiscompression or distortion is continuedfurther in the case of the cutting tool,owing to two main reasons; that of therelatively small cut, and to the factthat the resistance is continuous. Owinghowever, to the rake that is given tomost tools, this metal ,as it is crushedtogether, is forced to move along thepath of least resistance and when thecompression reaches a certain point, thechip is severed more by a tearing processthan the actual cutting of
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmachinery, bookyear19
