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Numerical Analysis of the Temperature Field Generated During the Production of a Fracture Notch in a C70S6 Steel Connecting Rod Using a Nd:YAG Laser
S-Q. Kou, J-W. Wang and Q-F. Zheng

Fracture splitting has become the focus recently for development in connecting rod manufacturing technology. The core process of fracture splitting is the pre-processing of a fracture splitting notch. This paper investigates how Nd:YAG laser processing can be used to generate a fracture splitting notch in a C70S6 steel connecting rod, looking at the working conditions of the laser grooving, developing a finite element analysis (FEA) model and then performing a numerical simulation of the temperature field generated during the laser grooving. In the evaluation of the numerical model the effects of varying parameters such as laser pulse power, spot size, traverse speed and pulse width on the different outcomes of the temperature field were compared. The change law with regard to the variation of depth and width on the fracture splitting notch was derived and the different manufacturing parameters that affect the formation, shape and the root radius of the notch were studied and discussed. The results indicated that: (i) The notch depth increased as the laser pulse power increased and the pulse width increased, and decreased as the spot size increased and the traverse speed increased; (ii) The notch width increased as both the spot size and the pulse width increased; (iii) The impact of the laser pulse power and traverse speed on the notch width was only minimal; (iv) An appropriate match between a long pulse width and the traverse speed was the key to obtaining a sharp fracture splitting notch; (v) A pocket- like hole was likely to form when the traverse speed was low and this hole would not be continuous when the speed was high; (vi) The notch root would not be sharp enough when the pulse width was short and some slag was likely to form near to the fracture splitting notch when the pulse width was long. Ultimately a set of optimal parameters were established.

Keywords: Nd:YAG laser, C70S6 steel, connecting rod, fracture splitting notch, temperature field, finite element analysis (FEA), numerical analysis

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