大型曲肱軸の鍛造法並に軸受部の捩りに就て

抄録

(1) Heavy crankshafts forged from a 20t or heavier steel ingots are generally formed first in a simple shape and then machined for the remained most part of finishing. It entails therefore unfavorable phenomena such as goasts on the surface of pins and journals. For avoiding such defects, a forging method was suggested that consists in preparatory forging nearly into the approximate shape of pins and journals, lessening the goast on the surface to minimum and thinning the apparent goast to the least. A 25t steel ingot was used for the experiment.
(2) In order to ascertain if the tors on of the journal will decrease the strength of the material, a torsional strength and fatigue test was performed with a journal of about 300mm both in diameter and length for each 30° of the torsional angle from 0 to 120°. The result revealed that the spicemen under torsion up to 90° were fonnd favorable in strength; and those under torsion up to 120° unfavorable, but still stands almost equal to the specimen without torsion.