Numerical Simulation On Transverse Knurling Connection Of Assembled Camshaft

Camshaft is one of the five key parts of automobile, its development promotes the development of automobile engine technology. Assembled camshaft made car's engine performance has been further improved, and compared with the traditional camshaft, it has many advantages: lighter weight, better performance, material using reasonable, lower cost, higher automation level and so on. It has very important significance in energy conservation, emission reduction and green manufacturing. For a short, assembled camshaft is the development direction of future camshaft manufacturing.Assembled camshaft make traditional camshaft into several working parts, such as cam, core shaft, neck journal, after then assemble those parts together. According to their working environment, we can take different design and manufacturing standard, thus improving the camshaft performance. In the assembly process, the connection between cam and core shaft is one of the technical difficulties, also an important part that can affect the performance of camshaft, so how to achieve high efficiency, strong connection is an important issue that engine manufacturing facing. This paper made in-depth analysis on transverse knurling connection of assembled camshaft, making a lot of simulation on assembled camshaft by finite element simulation technology, the main work is as follows:(1) Base on the analysis for connection mechanism of rolling assembled camshaft, we can identify two different mechanisms of connections. First one is cam material hardness is slightly greater than core shaft, both of them will deform in the pressing process, after deforming they embed in each other, this style camshaft depend on the connected force between cam and core shaft to resist torque. The second is cam material hardness is far greater than core shaft, cam will cut core shaft in the pressing process, cam does not deformed and mandrel deformed, finally make core shaft shape same as cam inner surface. The inner hole of cam made into polygon shape, so the connection of cam and mandrel rely on the shape to resist torque while working.(2) Research on the press mounting process of transverse knurling connection assembled camshaft by using finite element analysis (FEA) software. Using ANSYS and ABAQUS analyze the press mounting process of transverse knurling connection. We make the different analysis according to the different functions of the software: ANSYS is used to simulate the camshaft which material has similar hardness, for the hardness of material has great difference we use ABAQUS to simulate.(3) The influencing factors of press mounting of assembled camshaft were analyzed, I got different press force at different materials, shrinkrange , length of being connected, also research on other affected factors such as cam thickness, shaft diameter, I got some rules as follows:1) If the magnitude of interference, the thickness of the cam, the length of connected and other factors are constant, the press mounting force is greater when the material of cam is harder, but this influence is not very obviously.2) Other factors are the same, the press mounting force increase with the shrinkrange increase. But if the magnitude of interference is too big the cam should be caused pull cracks because of the large pressing force.3) The length of being connected is longer, the press mounting force is bigger while other influencing factors are constant.4) Cam thickness also can affect the press mounting force, the pressing force should bigger if the thickness of cam is bigger.(4) Pressing process is an important process of assembling camshaft, the quality will directly affect the camshaft connection. This paper has research on the wrest resistant that if torque that camshaft withstand greater than the maximum value, cam and core shaft relatively slid, camshaft failure. Usually the factors affecting torsion strength and the influence factors of pressing force are the same, the rules are:1) If other influencing factors are the same, wrest resistant property is better when the cam is harder;2) Wrest resistant property is better, when external diameter of the core shaft is bigger. But the bigger diameter of shaft will increase the camshaft's weight, that destroy the requirement of light weight;3) Similarly, increasing the length of the knurling connections can make the camshaft wrest resistant increase, but also can increase the weight;4) The connection between strength increases when the magnitude of interference is bigger without pull cracks, but it will make the pressing process difficult.To sum up, before manufacturing we must consider the working conditions of camshaft, thus we can choose the most reasonable material, connecting length, magnitude of interference and other parameters.The working face of camshaft is the surface of cam and neck journal, cam's performance will directly affect the performance of camshaft, so the cam manufacturing mode is one of the key technology for assembled camshaft. We must optimize the cam's property in the manufacturing process, thus it can resistant periodic load and shock. This paper has researched on the way of cam manufacturing.Near net-shape forming technology is a kind of advanced technology, that components can be directly put into use after forming without subsequent processing or little processing. This new technology can manufacture component with complex shape, processing is simple. Compared with traditional processing technology, this new technology has reasonable material using, high efficiency, low cost, good performance and other advantages.For assembled camshaft we often use powder metallurgy forging cams and warm precisely forging cams. Powder metallurgy shaping can according to the forming parts performance add different alloy elements, it provided new ideas to the development of new materials. Due to the near net-shape forming technology of many advantages, it will be able to become one of the most important processing method in the future.