Innovative Flexible Metal Forming Processes based on Hybrid Thermo‐Mechanical Interaction

Abstract

A new approach towards functional gradation of structural parts is presented. This approach is based on the utilization of locally varying thermo‐mechanically coupled effects applied to different initial workpiece geometries. The possible degree of freedom for the gradation of material properties and geometrical shape for sheet metal forming applications as well as for parts produced by bulk metal forming is characterized by the results of metallographic investigations, by mechanical testing and by an indication of the remaining residual stress state. On the basis of experimental results and process simulations, it could be revealed that the ability to exactly control the dynamic microstructural evolution by thermal and mechanical process parameters combined with predefined material design parameters constitutes a key towards the adjustment of flexible material property profiles even for parts with complex three‐dimensional geometry. Beyond that, the integrative aspect of thermal and mechanical treatment already implies the high level of obtainable efficiency resulting from shortening of process chains. However, it is not only the ability to integrate shape generation and property gradation, but also the automatically included positive effect of tailoring process behaviour by a gradation of formability finally allowing to improve process efficiency e.g. by a reduction of forming steps or reduction of (local) tool load.

Simulation of a Hybrid‐Forming Process using Temperature‐ and Rate‐Dependent Viscoplastic Material Models

“…So far the material parameters for the heat-treatable Fig. 1 Hybrid-forming tool: a) Photography, b) Simulated displacement normal to the forming surface after 50 cycles of thermal shock steel 51CrV4 used in the regarded hybrid-forming process [1] are not available. Therefore we assume material parameters obtained in [5] for a low-alloy steel.…”

“…In the investigated hybrid-forming process [1] cold forming tools of hot-working steel X37CrMoV5-1 interact with hot shafts of heat-treatable steel 51CrV4 in a cyclic manner for forming work pieces with graded material properties. In this process the forming tool is treated cyclically by small deformations due to cyclic thermo-mechanical loading and damage occurs.…”

“…In this contribution a hybrid-forming process based on the utilization of locally varying thermo-mechanical effects is investigated [1]. For process optimization and improvement of the resulting work piece the simulation of the entire forming process is necessary in modern engineering.…”

Deformation and Damage Analysis of a Hybrid‐Forming Tool under Thermal Shock Conditions

“…In the investigated hybrid-forming process [1] a hot work piece is formed by a set of two cold forming tools, Figure 2, right, made of the material X37 CrMoV5-1, in order to form a shaft with a specific geometry and with graded material properties like graded strength or stiffness distributions. In this process the forming tools are subjected to cyclic thermal shock considering forming many shafts with one set of forming tools.…”

Modellierung der Umwandlungsplastizität und Viskoplastizität niedrig legierter Stähle

“…Halbzeugen mit maßgeschneiderten Eigenschaften in Bezug auf Geometrie und Werkstoffverhalten führt in den letzten Jahren zur Entwicklung innovativer Fertigungsprozesse. Als neuartiges Umformverfahren wird in [6] …”