Study On Dynamic Balance Test Of Crankshaft Of Marine Diesel Engine Based On LabVIEW

Rotor imbalance is the main reason for the vibration of rotary machine and the exciting force resulting from it is one of the important factors that lead to vibration fault and damage of related moving parts as well as noise.As a special rigid rotor moving part,the crankshaft mechanism in marine diesel engine is easily damaged because of its varied motion forms,complex forces and own imbalance.Hence,to conduct study on testing and correction of dynamic balance for crankshaft system in marine diesel engine is of great significance in order to reduce failure of marine diesel engine,ensure its stable and efficient operation and increase its service life.First,the paper gives a brief introduction of mechanical vibration and makes an analysis of the current research on dynamic balance technology at home and abroad as well as something about dynamic balance of crankshaft.It also introduces the development of virtual instrument and Lab VIEW,a graphical programming language,and puts forward the research direction corresponding to the paper with the combination of actual operating and experimental conditions of marine diesel engine.Second,the paper has a research and analysis of the basic theory of rigid rotor dynamic balance,and conducts the study on kinematics and dynamics for crankshaft and connecting rod mechanism of diesel engine combined with the operating principle of marine diesel engine.It also analyzes the reasons for imbalanced vibration of marine diesel engine and its hazards,discusses the dynamic balance method to balance the imbalanced vibration of crankshaft and connecting rod mechanism of diesel engine.Taking the above study into consideration,the paper chooses field dynamic balance technology for crankshaft system.Third,the paper studies the key technology of dynamic balance test and measures thespeed and initial vibration signal of crankshaft.It separates the imbalanced signals with related filters,calculates the amplitude of imbalanced signals and achieves phase extraction with cross-correlation method and verifies the effectiveness of method with simulation.It designs an imbalance-correcting mechanism at the flywheel end to balance the imbalanced vibration and introduces influence coefficient method to study on field dynamic balance technology.It also equips and analyzes related hardware in the system and gives an introduction to the design process,interface,relevant program modules of the software for development and testing.In the end,it completes the design of field dynamic balance test for crankshaft system of marine diesel engine.Last,it conducts testing and verification for ship crankshaft system including measurement of initial vibration signal,separation of imbalanced vibration signals,zero gravity process,calculation of influence coefficient and balance after correction according to the implementation of dynamic balance and in an experimental way in order to verify the balance effect of the dynamic balance test system.The test shows that the system is easy in operation with a good balance effect,so the dynamic balance method for crankshaft system of marine diesel engine designed in the paper is feasible.