Hybrid tools for tube bending processes using additive manufacturing and digital twin

Forming tools are conventionally made from alloy steels with high material stiffness (Elastic Modulus). In comparison to alloy steels, polymeric materials are light weight and inexpensive. 3D printed polymeric tools are therefore suitable for manufacturing setups oriented towards customized productions. However, relatively low material stiffness limits the use of polymeric tools in production regime. This paper presents a novel concept of developing hybrid tools which consists of highly stiff metallic surfaces and 3D printed polymeric base. The hybrid tools are designed according to process parameters, tool material properties and contact pressure pattern at the tool’s mating surfaces. The contact surfaces of a hybrid tool behave like actuators which respond according to pre-computed applied loads. As test case, a hybrid forming tool (hybrid pressure die) is designed, developed and tested in a cold form tube bending process. FE-simulations are conducted with the digital twin of the tube bending process. The accuracy of digital twin is validated by conducting practical experiments. A comparison is made between hybrid pressure die and its erstwhile conventional counterpart (metal pressure die). Performance comparison is based on von Mises stresses, major strains, contact forces, failure risk, elastic deformations and surface displacements of the tools. Cost comparison is made on the basis of Ashby cost performance index. For the first time, a concept of in-process adjustment of tool surfaces in response to increasing tube diameter is presented. This research demonstrates that hybrid tools are cost effective and light weight alternative to conventional metallic tools used in production processes.