Locomotive boiler construction; a practical treatise for boilermakers, boiler users and inspectors .. . FigurePunched work. The Derry Collard Co. in strength in the section containing the hole. Fig. 63shows a portion of a plate with holes punched along itsedge. These holes decrease the strength of the platealong the center line of the holes in the following pro-portion : 101 Punches for boiler work. Let L = the pitch of the holes = inches Let D = the diameter of the holes = 1 inchLet S = the distance bet. the holes = inchesLet E = the efficiency of the plateL —D — 1 then E =-p—
Locomotive boiler construction; a practical treatise for boilermakers, boiler users and inspectors .. . FigurePunched work. The Derry Collard Co. in strength in the section containing the hole. Fig. 63shows a portion of a plate with holes punched along itsedge. These holes decrease the strength of the platealong the center line of the holes in the following pro-portion : 101 Punches for boiler work. Let L = the pitch of the holes = inches Let D = the diameter of the holes = 1 inchLet S = the distance bet. the holes = inchesLet E = the efficiency of the plateL —D — 1 then E =-p— = per cent. L This is about the percentage of strength of a platealong the third line of rivets of a triple riveted joint. Inaddition to the decrease of strength of the sheet, there. The Derry Collard A shearing 64A common punch. is also some tearing influence exerted upon the metalwhile being punched. This influence may extend for asixteenth or, in some cases, an eighth of an inch allaround the punched hole. It is on this account that allpunched holes are required to be reamed before the rivetsare driven. A sufficient amount of metal should be taken 102 Punches for boiler work. off by the reamer to remove all the affected metal. Al-though much has been said in condemnation of punchingsteel and iron plates, yet, in the business world, punchingis resorted to and almost wholly depended on. And thefailures traced back to the punch itself are few indeed. Quite a common punch is shown at P in Fig. 64. Itis attached to the stud S by a nut N, which holds it firmlyin position. C is a center tit, which is now almost en-tirely used in centering the punch in the work. The dieD is relieved at A so that the punchings can readily passthrough the hole. I
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Keywords: ., bookcentury1900, bookdecade1910, bookidlocomotivebo, bookyear1912
