The combined sheet and bulk forming process has a high potential for the near-netshape forming of metal components with thin and multiwall thickness. In this forming process, the bulk forming process, i.e., compressive forming process, is applied to sheet or plate workpiece in combination with the conventional sheet forming (stamping) process to minimize the material waste and manufacturing cost. The spin forming (flow forming, shear forming) as well as the combined stamping and forging are focused in this chapter, because these are key technologies for the combined sheet and bulk forming process. The basic process knowledge of these two technologies is provided with as for the working principles, deformation characteristics, important process parameters, forming process and tooling design, forming machine, case studies of application, etc.

The flow forming process can reduced the wall thickness of rotating cylindrical hollow workpiece into intended value incrementally, and shear forming can form various kinds of conical/semispherical/cup-shaped hollow components from flat disk-shaped workpiece of sheet metal. The advantages of spin forming are low-cost simple tooling, easy lubrication during forming, high flexibility in forming, and applicability to cold forming of high-strength and difficult-to-form materials. The optimization of forming process, forming parameters, tooling design, and initial workpiece design is required for successful spin forming.

The combined stamping and forging process includes the local compression of workpiece in its thickness direction for reducing wall thickness locally and some forming mode of conventional stamping of sheet metal. In this process, various kinds of thin-walled 2D/3D components with multi thicknesses, ribs, pins, and webs can be formed in near net shape from sheet workpiece of uniform thickness. The optimizations in forming sequence in multistep forming, lubrication, and tooling design are essential for successful forming.

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