How is the crankshaft machined? How many steps?

Obtaining pure hot metal with high temperature and low sulfur is the key to produce high quality ductile iron. In China, cupola is the main production equipment, and molten iron has not been pre-desulfurized; Secondly, there is less high-purity pig iron and poor coke quality. The molten iron is melted in cupola, desulfurized outside the furnace, and then heated in induction furnace to adjust the composition. Vacuum direct reading spectrometer has been widely used to detect the composition of molten iron in China.

2. Modeling

The air impact molding process is obviously superior to the clay sand molding process, and high precision crankshaft castings can be obtained. The sand mold made by this process has the characteristics of no rebound deformation, which is especially important for multi-throw crankshaft. Some crankshaft manufacturers in China have introduced air impact molding technology from Germany, Italy, Spain and other countries, but only a few manufacturers have introduced the whole production line.

3. Electroslag casting

The electroslag remelting technology is applied to crankshaft production, so that the performance of cast crankshaft can be comparable to that of forged crankshaft. It has the characteristics of fast research and development cycle, high metal utilization rate, simple equipment and superior product performance.

Extended data

Working principle of crankshaft

The function of crankshaft is to convert the gas pressure transmitted by piston connecting rod into torque, which is used as power output work to drive other working mechanisms and auxiliary equipment of internal combustion engine.

Matters needing attention in crankshaft maintenance

(1) In the process of crankshaft repair, carefully check whether the crankshaft has cracks, bends, twists and other defects, and the wear of the main bearing bush and the connecting rod bearing bush, so as to ensure that the fit clearance between the main journal and the main bearing bush, and between the connecting rod journal and the connecting rod bearing bush is within the allowable range.

(2) Crankshaft cracks mainly occur at the transition fillet between crank arm and journal, and at the oil hole of journal.

(3) When repairing and reassembling the crankshaft, the flywheel should be balanced.

(4) The crankshaft should be overhauled after major accidents such as tile burning and cylinder collision.

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