Machining method for grinding main journal of crankshaft in floating mode

Abstract

The invention relates to a machining method for grinding a main journal of a crankshaft in a floating mode. The method sequentially comprises the following steps: S1, clamping; S2, adjusting a bracket support; S3, rough grinding, wherein first rough grinding is conducted on an IV gear main journal through a grinding wheel 3, a bracket at the position corresponding to the IV gear main journal is adjusted while the IV gear main journal is ground, and during adjustment, it is ensured that the bracket is consistent in height, feeding scales of a grinding wheel frame handle are consistent, the practical size of the journal is consistent, and an error of a processing reference supporting gear is within + / -0.005mm; then, rough grinding is conducted on an IIV gear main journal and an I gear main journal, the more three reference supporting gears are ground in a reciprocating mode, the higher the grinding precision of the crankshaft is, and the coaxiality is better; S4, fine grinding, the step of rough grinding is repeated, fine grinding is conducted four to five times, after fine grinding, the main journal D=210mm, and tolerance ranges from 0mm to 0.029mm; S5, the remaining main journal is machined. Floating grinding is adopted in the machining method for grinding the main journal of the crankshaft in the floating mode, namely grinding is conducted on the crankshaft in the natural state, and influence of prestress, heat deformation and precision of a machine tool spindle is eliminated.

Description

technical field [0001] The invention relates to the field of diesel engine crankshaft processing, in particular to a processing method for floating grinding crankshaft main journal. Background technique [0002] The crankshaft is the main part of the diesel engine, and its processing quality directly affects the normal operation, service life and power performance of the entire diesel engine. Due to the large mass and poor rigidity of the crankshaft body, it is easy to deform during processing, and it is a large and difficult-to-machine part. During the machining process, the precision of the crankshaft is affected by external forces (cutting force, top clamping force, gravity centrifugal force) at any time, and is also affected by grinding heat during grinding, so the machining accuracy is not easy to guarantee. The crankshaft requires high precision, especially the coaxiality and roundness of the main journals of each gear is the key to ensure the quality of the crankshaf...

AI Technical Summary

Problems solved by technology

But this method is to use external force to adjust the crankshaft. Once the crankshaft is disassembled from the machine tool, in a free state, it will be deformed due to stress release, which will destroy the precision. This has been confirmed in the past grinding practice.

Due to the stress and deformation caused by the grinding of the two tops, the coaxiality of the crankshaft is out of tolerance, and other precisions are also out of tolerance due to its deformation. The deviation of the crankshaft is more than 0.03 mm. In the operation of the diesel engine, the different shafts of the main journals of the crankshaft will cause an additional dynamic load on the crankshaft, which will cause excessive wear of the bearing gear (commonly known as eccentric wear). The greater the coaxiality error, The more serious the wear of the journal, the more serious the wear of the connecting rod journal will be, which will seriously affect the service life of the diesel engine

[0007] In addition, if the main journal is directly ground on the crankshaft grinder, the two-top grinding is due to the synchronous operation of the crankshaft top and the head and tailstock spindle of the crankshaft grinder. The roundness error of the machined crankshaft journal caused by the running accuracy of the spindle is generally around 0.025 mm, which does not meet the requirements of the drawing

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