Numerical and experimental study on the rheo-extrusion process of 2A50 aluminium alloy miniature gear

Abstract

An innovative rheo-extrusion process for aluminium alloy miniature gears is proposed in this work to overcome the disadvantages of inefficiency and high cost in the existing forming methods. Numerical simulation and experiment were conducted on the rheo-extrusion process of 2A50 aluminium alloy miniature gear. Simulation results reveal that the metal fills into the cavity of the gear die along the axial and radial directions at different flowing velocities, mostly varying from 0 mm/s to 6 mm/s depending on the position of the metal in the gear die. The temperature of the billet rises with increasing extruded displacement, and the side of the gear near the punch has a high temperature of 593 °C at the end of extrusion. The equivalent stress of the parts in the billet near the top and bottom lands of the gear die is higher than others, with a maximum value of approximately 290 MPa at the top lands of the gear die when the extrusion is finished. The rheo-extrusion experiment shows that the miniature gear is fully filled, and its microstructure consists of fine grains with an average size of 19–31 μm. The micro-Vickers hardness distribution of the miniature gear is related to the grain size. The hardness of the parts near the dies are higher than others, with value of 81–85 HV, and the grains in these regions are finer than the other positions.

Keywords

• Rheo-extrusion
• Miniature gear
• Metal flow
• Microstructure
• Hardness