Study On Dynamic Balance Performance For Engine Crankshaft Die Forging

Crankshaft is an important part of automotive engine，and its movement patternis rotational movement. When deviation exists between the turning centerline and qualitycenterline of engine crankshaft, the centrifugal force and centrifugal moment of inertia ofcrankshaft is not to zero，which led to the crankshaft dynamic imbalance. When thedynamic unbalance of the crankshaft exceeds the allowable value, the rotation of thecrankshaft produces mechanical vibrations and noise，which will increase the wear of thebearings, shorten the life of the crankshaft, the lower end of the crankshaft balance rate.In this thesis, inline four-cylinder crankshaft is used as the main object, andcalculation has performed to its balancing performance, analysis and optimization. Firstly,static balance and dynamicing balance of the inline four-cylinder crankshaft areanalyzed.Secondly, according to the problem that it is diiffcult to achieve accuratecalculation of the current crankshaft balancing, a double-sided balancing algorithm wascompiled，and a crankshaft balancing calculation software was developed, which not onlycan calculate with high accuracy, but also facilitates the general engineering personnel tooperate. The working principle of this software is: In the UG NX modeling environment,ifnite equidistant division is done automatically to crankshaft entity along its rotationcenterline and a data ifle containing the motion characteristics of each slice of crankshaft:quality, turning centers, etc. is generated. Procedures written by Matlab software is used toextract the data ifle，and then to compile and calculate the data ifles based on the principleof rotor double-sided balance, ifnally getting the dynamic unbalance of the crankshaft. Inorder to test the calculate accuracy of the results, we use commercial software SolidworksSimulation for calculating the dynamic unbalance of the crankshaft. Comparing the resultsof two soft’wareresults show that the results of crankshaft balancing calculation softwareagree well with actual results, which indicates that the two methods can be applied topractical engineering. Finally, simulation of the crankshaft forging die wear has been done by using of commercial software DEFORM-3D, which showed that: the wear at inside andoutside ifllets of rod journal on the crankshaft forging die impact the crankshaft balancingmore signiifcantly. By improving the geometric parameters of the crankshaftcounterweights, the crankshaft balancing performance was optimized.This study uses a combination of mold CAD/CAE technology: a crankshaftbalancing calculation software was developed based on double-sides balancing algorithm,and the impact of die wear on the crankshaft balancing was analyzed based on theprinciples of viscoplastic ifnite element method, which not only can accurately calculatethe dynamic crankshaft balance, but also be able to eiffciently improve the performance ofthe crankshaft balancing, that provides an important reference for the study of crankshaftforgings balancing and a huge help for the actual production.