Characteristics of automobile curved surface drawing parts

[Erica Zhu Feilong Jiangli]

    Automobile surface drawing parts have the following characteristics:

    1.Deformation characteristics

    The deformation characteristics of large curved surface parts are as follows: the periphery is deep drawing, and the interior has bulging components. The surface shape is supplemented by the exterior material of the pressing surface and the interior by the material extension to meet the bulging requirements. At the same time, due to the deep drawing depth and complex shape, the distribution of deformation parts is uneven. Therefore, controlling the direction and velocity of material is extremely important. The part of large curved surface is easy to wrinkle and crack easily.

    2.There must be enough stable blank holder force.

    Large curved surface parts require not only certain drawing force, but also enough stable blank holder force in the process of drawing. This kind of workpiece is often a large contour size, deep space surface, so the need for deformation and blank holder force are larger. In the ordinary single-action press with air cushion, the blank holder is only about 1/6 of the nominal tonnage, and the blank holder force is not stable, it is difficult to meet the technological requirements of such parts, so in a large number of production, the drawing of such parts are carried out on double-action press. The double-action press has two sliders for drawing and blank-holder, i.e. inner slider and outer slider. The blank-holder force can reach more than 40% - 50% of the total drawing force. It can satisfy the requirement of uneven distribution of deformation around the workpiece, and the blank-holder force is stable, and it is easy to get the deep-drawing parts with better stiffness.

    3.The drawing parts must have enough stiffness.

    Most of these parts are used as the exterior of the machine, requiring sufficient stiffness (no trembling and noise in use) and dimensional stability (to ensure the quality of welding and assembly). This requires that all parts of the material be subjected to uniform tensile stress (ideally a two-way tensile stress state) in the drawing process, and that the tensile stress exceeds the yield limit, but is lower than the strength limit, so that the elastic recovery of the workpiece is reduced to a minimum, so that the shape is not distorted, but also not rupted.