Evaluating the quality of assembled camshafts under pulsating hydroforming

This paper introduces an evaluation method for the quality of assembled camshafts under pulsating hydroforming, aimed at laying a certain foundation for the automobile engine industry in the future. The novelty of the design lies in applying a pulsating hydraulic pressure to the interior of a hollow shaft such that it exhibits an interference fit with the cam (cam-bores with non-circular structure) after being deformed by the pressure. A camshaft with a trilobe polygonal inner profile is selected and studied by conducting experiments and finite element analysis. The quality of the camshaft varies with the process parameters (pulsating amplitude, pulsating frequency, and hydraulic pressure). The effects of these parameters are investigated by evaluating the filling rate of the shaft and torsion strength of the assembled camshafts. Moreover, a new measurement method for the filling rate of the shaft is developed. Finally, the quality of a pulsating, hydraulically assembled camshaft is compared with that of a non-pulsating hydraulically assembled camshaft, thereby validating the proposed evaluation method. The preliminary feasibility of the pulsating hydraulic connection for the assembled camshafts with a trilobe polygonal profile is demonstrated in this study.