Application of machine learning on tool path optimisation and cooling lubricant in induction heating-assisted single point incremental sheet forming of Ti-6Al-4V sheets

Abstract

Induction heating-assisted single point incremental sheet forming was established for Ti-6Al-4V thin sheets at closed and above beta-transus temperature (980 °C). In order to eliminate geometric inaccuracy and adherence of lubricant on the surface caused by elevated temperature, a cooling lubricant system was designed for the forming tool to decrease the thermal expansion and friction. A radial basis function (RBF)-based tool path optimisation was developed to study the measured geometric accuracy, temperature, and forming force. By adjusting cooling lubricant control and integrating the RBF framework, the first optimised tool path was used to collect the results and to validate with the finite element (FE) model and theoretical geometric profiles. The output data were further studied by RBF and generate a second optimised tool path. The measured geometric coordinates revealed that the error percentage has been reduced to less than 5%. Further, the microstructure evolution analysed by scanning electron microscopy (SEM) indicated noticeable oxidation and alpha-layer for temperature around 1040 °C and the phenomenon was removed at temperature closed to 950 °C. The surface roughness and energy-dispersive X-ray analysis (EDX) revealed the optimised tool path distributed significant improvement in surface quality. The cooling lubricant system indicated optimal performance with RBF optimised tool path to support constant temperature and reduce friction and lubricant adherence on the surface.

Heat-assisted incremental sheet forming for high-strength materials — a review

“…The study applied a self-mixed liquid MoS 2 to pass through the ball roller to reduce the thermo-expansion during the process. The findings show that liquid lubricant helps reduce the springback [67] and enhances the surface quality where the wear marks and abrasive lubricant adhesion have been significantly removed.…”

“…According to the study, the tool provided high-performance levels in the electric heating-assisted SPIF process for Ti-6Al-4 V at 500 °C. Similarly, another study by Li et al [67] investigated on the proposed water-cooling ball-roller design in an induction heating-assisted SPIF process for Ti-6Al-4 V at 950 to 1100 °C. Figure 16b illustrates that the difference in this design is the orientation of the lubricating balls between the ball roller and the tool wall.…”

“…Water-cooling ball-roller tool design. a Water-cooling ball-roller tool[19], b water-cooling ball-roller tool with assisted cooling design[67]…”

Advanced FEM Insights into Pressure-Assisted Warm Single-Point Incremental Forming of Ti-6Al-4V Titanium Alloy Sheet Metal

“…As is presented in the Section 3, uniform thinning of the sheet metal along the perimeter of the drawpiece was observed. This assumption was also the subject of research by other authors examining the SPIF of titanium and its alloys [45][46][47]. Models of flow curves (Figure 7a) at temperatures between 183 and 340 °C were prepared by approximating the experimental curves using the approach proposed by Naranjo et al [35].…”

Selection of Constitutive Material Model for the Finite Element Simulation of Pressure-Assisted Single-Point Incremental Forming

“…It was shown that the two-stage forming technique could significantly reduce the geometrical deviation, thickness variation, and forming time. Li et al [34] investigated the tool path optimisation of induction heating-assisted SPIF using machine learning. Material formability and surface quality were improved following the optimisation of the tool path and using machine learning; however, noticeable oxidation and alpha layer of the sheet material at heating temperature ~1040 • C were reported, and they were eliminated at ~950 • C. Frikha et al [35] explored incremental forming of grade 2 α titanium for biomedical application (hip cup prostheses).…”