Crankshaft.

摘要

A crankshaft including a pair of crank webs (3, 4) located in spaced juxtaposed relation, and a crank pin (5) connected between the crank webs (3, 4) for rotatably journaling a piston rod (7) at one end. A pair of openings (12, 13) for receiving opposite end portions of the crank pin (5) are formed at eccenttric points on surfaces of the crank webs (3, 4) which are opposed to each other. The crank pin (5) is formed on one end portion with an irregular surface portion (5A) having a plurality of peripherally extending rows of elevations and depressions and on the opposite end portion with a slitted surface portion (5B) having a plurality of axially extending slits. The one end portion of the crank pin is inserted in the opening (12) formed in one of the crank webs (3, 4) and pressure is applied locally to a portion of the crank web (3, 4) disposed in the vicinity of the opening to induce same to undergo plastic deformation and cause its material to flow to the irregular surface portion (5A) of the crank pin (5). The other end portion of the crank pin (5) is force-fitted in the opening formed in the other crank web (4, 3) to induce a portion of the crank web disposed in the vicinity of the opening to undergo plastic deformation and cause its material to flow to the slitted surface portion (5B) of the crank pin. Thus the crank case is bonded at opposite end portions to the crank webs in metal-to-metal plastic bond with a clamping force and a shearing force produced by the material of the crank webs (3, 4).