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Crankshaft Manufacturing Process Revealed

2022-07-25

The crankshaft is the main rotating part of the engine. After the connecting rod is installed, it can undertake the up and down (reciprocating) movement of the connecting rod and turn it into a cyclic (rotating) movement.
 
It is an important part of the engine. Its material is made of carbon structural steel or ductile iron. It has two important parts: the main journal, the connecting rod journal (and others). The main journal is installed on the cylinder block, the connecting rod journal is connected with the big end hole of the connecting rod, and the small end hole of the connecting rod is connected with the cylinder piston, which is a typical crank-slider mechanism.
 
Crankshaft processing technology

 Although there are many types of crankshafts and some structural details are different, the processing technology is roughly the same.


Main process introduction

(1) External milling of crankshaft main journal and connecting rod journal During the processing of crankshaft parts, due to the influence of the structure of the disc milling cutter itself, the cutting edge and the workpiece are always in intermittent contact with the workpiece, and there is an impact. Therefore, the clearance link is controlled in the entire cutting system of the machine tool, which reduces the vibration caused by the movement clearance during the machining process, thereby improving the machining accuracy and the service life of the tool.
(2) Grinding of crankshaft main journal and connecting rod journal The tracking grinding method takes the centerline of the main journal as the center of rotation, and completes the grinding of the crankshaft connecting rod journal in one clamping (it can also be used for main journal grinding), grinding The method of cutting connecting rod journals is to control the feed of the grinding wheel and the two-axis linkage of the rotary motion of the workpiece through CNC to complete the feed of the crankshaft. The tracking grinding method adopts one clamping and completes the grinding of the crankshaft main journal and the connecting rod journal in turn on a CNC grinding machine, which can effectively reduce equipment costs, reduce processing costs, and improve processing accuracy and production efficiency.
(3) The crankshaft main journal and connecting rod journal fillet rolling machine tool is used to improve the fatigue strength of the crankshaft. According to statistics, the life of the ductile iron crankshaft after fillet rolling can be increased by 120% to 230%; the life of forged steel crankshafts after fillet rolling can be increased by 70% to 130%. The rotational power of the rolling comes from the rotation of the crankshaft, which drives the rollers in the rolling head to rotate, and the pressure of the rollers is implemented by the oil cylinder.