Research On The Transverse Knurling Connection Mechanism Of Assembled Camshaft And Numerical Analysis On The Press Mounting And Torsion Process

The assembled camshaft is a new technology of camshafts manufacturing and is also the impetus which is pushing the automobile engine manufacture industry development. Comparing with the traditional camshaft, the assembled camshaft has many merits, such as light in weight, low in processing cost, high in production efficiency, all of which can improve the performance of engine and market competitiveness. The assembled camshaft has been the main developing object of camshaft manufacture. Researching on the connection technology of the assembled camshaft has become an important task in the automobile engine manufacture industry.The transverse knurling connection method is adopted in this paper. Based on the method, the transverse knurling connection assembled camshaft is researched profoundly. Under the premise of the knurling connection technique, plentiful experiments and FEM simulation analysis have made in the paper. The main tasks are as follows:(1) Aiming at the transverse knurling interference fit connection technology of assembled camshaft, the press mounting and the static torsional experiments have been done by choosing different specification and parameters.According to the new connection technology by transverse knurling interference fit, the press mounting and the static torsional experiments are performed at various magnitude of interference and tooth spacing and moreover the press mounting force and the torsional strength that the assembled camshaft can bear after press mounting are obtained after these experiments. The results show that transverse knurling connection assembled camshaft has higher connection strength, and can successfully guarantee automobile engine performance. Afterwards the experimental findings of the camshaft sample of which the knurling effect is better are applied to use as the reference standards to the numerical simulation.(2) Using FEM numerical simulation technique, the press mounting process of transverse knurling connection assembled camshaft is approximately analyzed.CATIA, Hypermesh, ANSYS/LS-DYNA and lsprepost are applied to simulate the press mounting process of the transverse knurling interference fit assembled camshaft approximately. The simulation results indicate that the maximum value of the press mounting force in the press mounting process by approximate simulation can fit the value of experiment well.(3) Using FEM numerical simulation technique, the static torsional process of transverse knurling connection assembled camshaft is approximately analyzed.After the stress field that remained after press mounting process simulation is forward transferred, the static torsional strength under the effect of the torque force is analyzed by numerical simulation. The simulation results show that the maximum value of the static torsional strength in the static torsional process by approximate simulation can fit the value of experiment well. The simulation results are accurate and credible, and it can be used to guide the productive practice.(4) The factors which affect the press mounting force and connection strength of the transverse knurling connection assembled camshaft are discovered. The influence rules by which the factors including materials, assembly magnitude of interference, the thickness of the cam, the external diameter of the core shaft and so on affect the press mounting force and connection strength of the assembled camshaft are obtained.The influence rules by which various factors affect the press mounting force are as follows:1) Under the premise that the magnitude of interference and the thickness of the cam are constant, the influence that the material hardness affect the press mounting force is little;2) When the thickness of the cam and the magnitude of interference are approximately constant, the press mounting force is bigger when the external diameter of the core shaft is bigger;3) When the materials are the same and the thickness of the cam is constant, the press mounting force is bigger when the magnitude of interference is bigger. As the magnitude of interference is the most notable factor which affect the press mounting force, the knurling measure should be controlled appropriately when the assembly machine used for the transverse knurling connection assembled camshaft is designed. Therefore on the basis of which the connection is firm, the magnitude of interference should be smallest.The influence rules by which various factors affect the connection strength are as follows: 1) Under the premise that the diameter and the thickness of the cam are constant, the connection strength is better when the cam is harder;2) If external diameter of the core shaft is bigger, the connection becomes easier. But meanwhile the weight of the camshaft becomes heavier. It is contrary to the light weight principle of the camshaft;3) Under the premise that the materials of the cam are the same, the connection strength is better when the cam is thicker. But meanwhile the weight of the camshaft may also become heavier. Therefore the idea of increasing the connection strength by increasing the thickness of the cam can be carried out hardly;4) When the materials and the dimensions are the same, if the intertooth space of the knurling tool is bigger, the magnitude of interference is bigger, and furthermore the connection strength becomes better. But if the magnitude of interference is oversize, the press mounting force may become bigger. Therefore on the basis of which the connection is firm, the magnitude of interference should be chosen properly. That is to say the intertooth space of the knurling tool should be also chosen reasonably.