What are the materials of the crankshaft?

Crankshaft is an important part of internal combustion engine. It is no exaggeration to say that the quality of the crankshaft directly determines the quality of the whole engine. Therefore, it is very important to strictly control the materials and processing technology of the crankshaft. Today, Nuo will talk with you about: What are the materials of the crankshaft? What are the crankshaft excircle machining processes?
What are the materials of the crankshaft?
Crankshafts are mostly made of nodular cast iron and alloy steel. Generally, for gasoline engine crankshafts and small diesel engine crankshafts, due to their low power, the crankshafts are made of nodular cast iron and high-quality carbon steel. Common materials include QT700-2, 45 steel, etc; The crankshaft blanks of medium and heavy diesel engines are made of alloy steel, and the common materials are 48MnV, 35CrMo, etc.
What are the crankshaft excircle machining processes?
The main processing procedure of crankshaft excircle processing is to process the main journal, connecting rod journal, flange and shaft head. This processing procedure is located after the workpiece is milled and the center hole is drilled, and it is sometimes necessary to process the side of the balance block according to the specific situation. At present, there are three processing technologies for this part.
1. Turning technology
Multi tool turning is a typical processing method of crankshaft journal excircle. The production line is composed of ordinary lathe and special lathe, with low cost and large machining allowance. Large width formed turning tools are often used for multi cutter cutting. The workpiece is prone to deformation due to excessive cutting force, resulting in large radial runout. Straightening and rough grinding are often required after turning, resulting in low production efficiency.
2. Turning and drawing process
The outstanding advantage of the turning and turning process is that the crankshaft with wide shaft diameter can be processed layer by layer, and the journal, round corner and side face of counterweight can be processed in one clamping process, which is suitable for processing the crankshaft with undercut. When machining, multiple tools are installed on the cutter head, which can improve the cutting efficiency and accuracy. After machining, it can be directly refined to improve the efficiency. However, turning and broaching are the same as multi tool turning. When machining the main journal and connecting rod journal, they are still processed separately after their respective axes are positioned. In order to avoid generating excessive inertial force when machining the outer circle of the connecting rod journal, it is necessary to dynamically balance the machine tool spindle system (including the chuck and the workpiece).
3. Milling process
There are two kinds of milling: internal milling and external milling. When machining the connecting rod journal, the NC system controls the motion path of the cutter relative to the workpiece to make it composite into the outer circle of the connecting rod journal.