Analysis on the Interference Assembly of Camshaft With Knurled Tube and Cam

Interference joint is one of the most advanced assembly methods for camshaft. The joining force in the assembly process and the connection strength after assembly are the key aspects of the camshaft assembly system. In this paper, the mechanism of joining force and connection strength are analyzed from two aspects of elasticity and plasticity using thick-wall cylinder model. Joining and torsion experiments are done to determine the joining force and connection strength. Joining forces fluctuating increase in the joining process, which is composed by friction force Fs and shearing force Ff. Fs is 0.87 KN, and Ff is 6.23 KN when the assembly interference is 0.15mm. Joining force linear increases with the interference, and torque exponential increases with it. The empirical formulas between the torque capacity, joining force, and interference of the camshaft are provided by the experiment results. The assembly interference limit of 0.3mm is estimated for the case of this paper. Metallographic observation reveals the changes of metal flow line of the knurled tube. The top of knurled tooth turns over and an inverted triangle formed after joining process.