Analysis The Processing Technology And Cam Surface Machining Error Of Engine Camshaft

Camshaft is a key part in the engine which driving the valve open and down directly. Asthe technology development, we need the quality of camshaft to be better and better,especially to the processing quality of cam. Because of the particularity of cam profile andcosts problems, many factories in domestic take use of the profiling method to grind cam. Theadvantages of this method are simplicity of operator and low costs, the fault is that theprocessing error is a little bigger, so how to settle this problem in existing facilities is veryimportant.The researching object of this paper is135diesel engine’s camshaft. According the analysisof its process and key process steps to propose an improving process program, this programhas some advantages in processing precision and processing efficiency relative to originalplan.Analyzing the processing characteristics of the cam, the main causes of the process errorare low accuracy of contour manufacturing, the changing of metal rubs elimination rate inunit time, sudden changing of grinding force and abrasion of grinding wheel. If the processerror is big, the performance of valve mechanism will be changed, and the valve mechanismwill not complete its function which is according to the original designing.This paper uses two methods to analyze the valve mechanism’s influence of process error,one is kinematics and the other is dynamics. The first method which uses the pieces-polynom-ial fitting of MATLAB is to analyze the tappet and valve’s movement rules, and then find theinfluence of the process to the system rolling characteristics with contrastive analysis. Fromthis method, we can obtain the tappet’s lift function, and then make the full-scale mock-up ofcam according the function with Pro/E. The second method is dynamics analysis to the camand tappet, input the model produced by Pro/E into LS-DYNA FEM software to do dynamicsimulation. Compared with the result of kinematics analysis, the law of motion curve changedobviously in dynamic result, especially the accelerated mutation that caused by processingerror, the mutation is very severe.The processing error is not only changing the motion law of valve mechanism, but alsoincreasing the contact stress of cam and tappet. And the direct results of these alternations arethat the valve mechanism’s abrasion and noise will be serious to reduce its using time.The paper proposes several measures at the last to reduce the processing error according tothe analysis above. And whether theoretical feasibilities or practical costs, these measures canbe used to solve the problem of big processing error efficiently.