Method for forging large ship crank shaft

Abstract

The invention discloses a method for forging a large ship crank shaft, which comprises the following process steps of: making a blank, chamfering a high-strength alloy steel ingot, upsetting, drawing the ingot into a steel blank with a round cross section; centering a V-shaped lower mold, a steel blank and an upper pressure block on a water press or an oil press; driving the upper pressure block by using the water press or the oil press to press the steel blank downward till the steel blank bends toward the inner cavity of the mold; removing the steel blank, and inserting a clapper into the bend opening part of the steel blank; flatting the bend opening of the steel blank by using a flat chopping block to form the semi-finished crank shaft; performing isothermal normalizing on the semi-finished crank shaft; and refining the semi-finished crank shaft subjected to isothermal normalizing to obtain the finished crank shaft.

Description

technical field [0001] The invention belongs to the field of forging, in particular to a bending forging method of a large marine crankshaft. Background technique [0002] The marine crankshaft is one of the key components of the marine diesel engine. It is subjected to periodically changing bending and torque moments during work, and at the same time bears the effects of inertial force and vibration additional stress and alternating loads. The crankshaft is prone to fatigue damage during work, causing the crankshaft to break, which directly affects the safety of the hull equipment. Therefore, technical parameters such as strength, stiffness, and wear resistance of marine crankshafts have very high requirements. [0003] At present, the manufacturing method of large-scale marine crankshaft parts is generally made of cut fibers, that is, the steel ingot is pressed into a flat shape similar to the shape of the crankshaft, and then the main journal of the crankshaft and the jo...

AI Technical Summary

Problems solved by technology

Therefore, the crankshaft manufactured by the cut fiber method can no longer meet the development requirements of large ships. At present, there are two methods of preparing full-fiber crankshaft forgings in the world: bending forging and die forging. The process is short, the machining cost is low, and the material utilization rate is high. However, because different crankshafts require different molds, the tooling costs are high. Only specific types of crankshaft forgings can be produced, and the manufacturing of molds is difficult. The mold needs to be preheated, and the operation process of changing the mold is complicated, so it is rarely used in actual production