| 摘要 |
PROBLEM TO BE SOLVED: To apply better straightness to a crankshaft by assembling separate crank web units one at a time to a shaft blank having a different diameter in different points, and lastly cutting off the portion of the shaft blank corresponding to a crank pin. SOLUTION: The diameter of a shaft blank 1 is at its biggest in the central portion and decreases toward the both ends, a crank web unit 2 is located at the point of the shaft blank 1 with the biggest diameter, then other crank web units 2 are installed on both sides as the diameter of the shaft blank 1 decreases. The shaft blank 1 has cylinder portions arranged in steps in the axial direction in sequence, and the crank web unit 2 is fixed to the portions by shrinkage fitting 4. After the crank web unit 2 is fixed to the shaft blank 1, the shaft blank 1 is machined into a prescribed shape. The portion of the shaft blank 1 at the position of a crank pin 2b is completely cut off so that a connecting rod fitted to the crank pin 2b can be rotated. |
