Research On Rolling Equipment Development And Process Improvement Of Marine Crankshaft

Crankshaft,as a rotating part of engine,is always one of the key parts in the whole engine design for simulation.How to strengthen the key parts of crankshaft is the key technology of machining technology.For a long time,we have used the way of nitridation heat treatment to strengthen the crankshaft,but this process has low efficiency,large energy consumption,prone to oxidation or deformation in the nitridation process.Many automotive internal combustion engine enterprises use crankshaft rolling as a way to improve the fatigue strength of crankshaft and has been applied,so the extension of crankshaft rolling to Marine crankshaft processing can also achieve the increase of crankshaft local strength,However,the present Marine diesel crankshaft fillet was achieved by rolling strengthening case still is scarce in the domestic manufacturing,advanced processing equipment of large crankshaft grinding machine,such as car milling compound machining center,servo not to popularize and apply in the domestic enterprises,such as deformation factors in machining crankshaft itself controllability is poor,if undertake rolling will greatly increase the application is not controllable factors,qualified rate of the crankshaft can't get effective control,so the application of the rolling technology not formed mature technology in the enterprise.In this paper,the crankshaft fillet rolling of Marine diesel engine is realized through technical transformation of the old equipment with lost precision.According to the data analysis and experience of rolling test,the original crankshaft process is optimized,and the replacement or supplement of nitriding heat treatment is realized in crankshaft production.The main design contents of this paper are carried out from the following aspects:Firstly,the successful cases of crankshaft surface strengthening and stress analysis are compared to confirm the feasibility of rolling strengthening.secondly,determine the stress concentration part of the crankshaft according to the stress condition under the working condition of the crankshaft,carrying out finite element analysis on the working parameters of the QT800-2 crankshaft in the running process and calculating the alternating stress magnitude,determining the size of the preset pressure stress at the crank angle of the crankshaft and providing theoretical parameters for the input pressure of the configuration clamp,and realizing the calculation of the pressure conversion to improve the accuracy of stress conduction.Thirdly,Determine the basic structure design of crankshaft reconstruction project,including hydraulic system,control system,lubricating system and roller clamp structure.Add the design of single side round Angle roll pressure of crankshaft,and strengthen the Angle of the main shaft diameter of the crankshaft.Fourthly,control the Crankshaft rolling process,and determine the parameters of crankshaft before rolling,including roll pressure,pressure,speed,etc.Sort out and compare the data after rolling.Set up the alignment plan after crankshaft rolling according to on-site inspection measures to ensure that the axial diameter of the crankshaft after rolling not exceeding the requirement of nitride crankshaft,so that the crankshaft working in the machine can be ensured.Fifth,The problems and countermeasures of crankshaft in equipment modification and rolling test,,avoiding the increase of crankshaft defects and damage to machined surface caused by rolling,ensuring that the surface hardness of crankshaft will be increased by 30%after rolling,and the surface roughness is increased by a precision grade.