Research on a wrinkle-free forming method using low-melting alloy for sheet metal

A wrinkle-free and no allowance forming method for sheet metals was investigated using a low-melting alloy (LMA) in this work. Using the low-melting alloy as a medium to transfer and provide a uniform pressure over the entire surface of the workpiece to form the sheet. When loaded evenly, the forming pressure could effectively prevent instability and wrinkling occurrence in the plate during the forming process. The blank could be formed into the target piece by proposed method without the need for machine allowance, which could improve the utilization ratio of material and eliminate the need for a trimming process for sheet metals forming. The low-melting alloy under heating has a low rheological strength and plasticity, which produced the corresponding flow following deformation of the sheet. The forming principle of the wrinkle-free method was analyzed through the principal stress method. The finite element software ABAQUS/Explicit was employed to establish the coupling fluid-solid FEM for low-melting alloy forming, while the formability and reduction of the sheet metal were analyzed numerically. The effects of the thickness, friction coefficient, forming force, and other process parameters of the alloy on sheet forming were studied. The experimental results show that the proposed method can significantly prevent wrinkling and instability occurrence in forming process and improve utilization of the material.