The Study of Multi-Stage Cold Forming Process for the Manufacture of Relief Valve Regulating Nuts

Abstract

Cold forging is widely used in many industries. Multi-stage cold forming is usually utilized in forging fasteners. In this study, numerical simulation and experimental investigations were carried out on a five-stage cold-forming process for the manufacturing of low-carbon steel AISI 1010 relief valve regulating nuts. The forming process through five stages included preparation and centering for backward extrusion, backward extrusion over die pin, upset, backward extrusion over moving punch, and piercing. The formability of the workpiece was studied, such as the effects on forming force response, maximum forming force, effective stress and effective strain distributions, metal flow patterns, and strength. A comparison of the forming forces obtained in the forming experiment with the numerical simulation results of the five-stage cold forming showed a good agreement with the trend of the forming force growth. For the maximum forming force and forming energy, the fourth stage of backward extrusion over the moving punch at the upper face was the largest among the five stages. The total maximum forming forces from the first to the fifth stages were numerically 440.9 kN and experimentally 449.4 kN, meaning the FE simulation and experimental results were in good agreement. The numerically simulated effective strain distributions were consistent with the experimentally tested hardness distributions. Highly compacted grain flow lines also resulted in higher hardness. The overall hardness of the workpiece formed by five-stage cold forming increased by 31% compared to the initial billet. The hardness of the workpiece increased with the forming stages, and the strain-hardening effect was obvious. The strength of the workpiece was significantly increased by five-stage cold forming.

Analysis of a New Process for Forming Two Flanges Simultaneously in a Hollow Part by Extrusion with Two Moving Dies

“…The numerical model of the process took into account the heat flow between objects and the increase in the temperature of the workpiece due to plastic deformation. The contact conditions between the rigid objects and the rigid-plastic object were described using a heat transfer coefficient of 10 kW/m 2 K and friction factor of 0.1 [3,28,29].…”

Adjust operating conditions of an in-made house horizontal hydraulic press for a 90° cold bending process

“…Cold forming or forging is a highly efficient process for shaping material profiles. A metal plate is creatively deformed within a tooling using a press at room temperature [1][2][3]. Predicting and controlling elastic recovery (SB, spring back) during bending processes is one of the principal challenges as it depends not only on the bending process parameters but also on the raw material's inherent characteristics and processing [4][5][6][7][8].…”

“…Excessive load is often the cause of premature damage to pre-forming tooling or dies, despite their ability to withstand high levels of stress and wear due to their design. Despite being classified as perishable tooling, they are engineered to resist fatigue and friction contact [1,[31][32][33][34].…”