Experimental and numerical study on warm single-point incremental sheet forming (WSPIF) of titanium alloy Ti–6Al–4V, using cartridge heaters

Abstract

The single-point incremental forming process is an emerging process, which presents an alternative to the conventional sheet metal forming processes like hydroforming and drawing. It is known to be perfectly suited for prototyping and small series. For example, the incremental forming process offers the possibility of manufacturing medical prosthesis or implants specific to each patient, which are more comfortable and guarantee better performance. The customization of this type of product brings better efficiency and better comfort. However, the manufacture of customized titanium prosthesis is not yet industrialized, mainly due to the geometrical inaccuracy of the parts and inability to form parts with a high wall angle. In fact, considerable forces and damage occur during the process limiting the formability. Several studies have already shown that increasing the working temperature allows improving the formability. A reverse engineering approach associated with warm single-point incremental forming process, in order to produce a customized titanium prosthesis, can make the ability to be exploited in the industry to manufacture titanium alloys medical shapes. In this paper, an experimental and numerical study of the warm incremental process based on the use of heat cartridges is performed. The objective is to demonstrate that our low-cost heating system can be used in forming limit angle similar to that obtained with expensive laser heating. The effects of the wall angle at 450 °C on the forming force, thickness distribution and displacement are investigated by producing a truncated cone with Ti-6Al-4V thin sheets. Results show that the formability is significantly improved with the heating. In addition, a thermo-viscoplastic constitutive model is used to simulate the warm incremental forming process. A comparison of the numerical and experimental results shows that the finite element model gives accurate predictions.

Accuracy and Sheet Thinning Improvement of Deep Titanium Alloy Part with Warm Incremental Sheet-Forming Process

“…The simulation of the warm incremental forming process was performed with two values of truncated cone depth: the same values as those studied experimentally (h = 40 mm and h = 60 mm). In previous work [27], the results of the tests carried out with the WSPIF setup on a titanium alloy Ti-6Al-4V sheet at T = 450 • C show that it is possible to produce smooth seines truncated cones without fracture appearance for a wall angle not exceeding (α = 56 • ) and depth (h = 40 mm).…”

“…The tool path was the same one used during the experiments with warm SPIF. The interaction between the blank and the spherical punch was defined by an isotropic Coulomb's friction model (µ = 0,1) [27,29].…”

“…Using optimized process parameters such as the step size, tool diameter, and tool path [26], we investigate in this study the effect of forming the step depth of Ti-6Al-4V alloy at warm temperature between 300 and 700 • C on the thickness reduction distribution and truncated cone profile. Numerical simulation is proposed to investigate the thermo-mechanical behavior depth of Ti-6Al-4V alloy during the deep WSPIF forming process in order to predict the thickness distribution and the final profile shape [27].…”

Single-Point Incremental Forming of Titanium and Titanium Alloy Sheets

“…Another paper that analyzes the behavior of the Ti-6Al-4V alloy during hot single-point incremental forming is presented by Saidi et al [ 116 ]. The novelty factor of this study is that the authors are replacing the expensive laser heating systems that perform local heating on the forming area with a cheaper alternative based on heat cartridges.…”

“…The effect of the proposed model on the forming forces and the final geometry was investigated. Saidi et al [ 116 ] investigated the warm incremental process of Ti-6Al-4V sheet based on the use of heat cartridges. The objective was to demonstrate that our low-cost heating system can be used in forming a limit angle similar to that obtained with expensive laser heating.…”