Effects of the relative tool rotation direction on formability during the incremental forming of titanium sheets

Abstract

The effects of tool rotation direction during single point incremental forming of pure titanium were experimentally studied. Axisymmetric components with a varying wall angle were formed using a round-tipped tool of 10 mm diameter and following a 3D spiral tool path. Test runs were executed by changing one factor at a time. Spindle rotation was tested in both the climb and the conventional directions. Tool step depth between runs was increased by a fixed interval over the range of 0.35 mm up to the plate thickness of 0.8 mm. The experimental results obtained by a comparison between the two forming strategies and their impact on the characteristics of formability are discussed in this paper. The achieved level of the forming angle (75°), and the reduction in geometric deviations from the conventional strategy, presents interesting findings. Considerable variations in the trends of forces and temperature between the two forming strategies are presented and discussed.

Formability of titanium alloy sheets by friction stir incremental forming

“…When compared to the marginal effects noted for the conventional strategy, the results from the climbing strategy over the same stepping range were very similar in terms of variation in temperature and forces. This is in contrast to findings related to the grade 2 titanium sheets reported in [22], to which considerable effects on formability, geometric accuracy, forming forces, and forming temperature between the two forming strategies (climb and conventional) were observed.…”

“…Throughout the OFAT test, the values f = 625 mm/min, n = 1940 rpm, and Δz = 0.3 mm were set as the reference values for the parameters. The range and reference level were chosen from a previous inhouse study on SPIF of grade 2 titanium sheets [22,23]. This was made to allow evaluating and understanding the two material behavior and effect on outputs, via comparing results between the two studies under similar forming conditions.…”

Single-Point Incremental Forming of Titanium and Titanium Alloy Sheets

“…Elevated rotation speeds decrease forming forces by increasing contact temperature, although they rapidly increase tool wear and remove material from the sheet surface. The relationship to feed rate rotation direction, climb or 'conventional' (see Figure 15) is also a key parameter, as Uheida et al [96] investigated in VWACF of Grade 2. Conventional type forming has higher forming temperatures and lower vertical and horizontal forces, leading to better accuracy and a higher forming angle in comparison to climbing.…”

“…In general, heating systems in thermal-assisted ISF processes can be classified as [ 86 ]: Radiation—a laser light follows the tool trajectory (the workpiece is heated at the actual location of forming) [ 87 , 88 , 89 ], Convection—hot air blowers heat the entire metal sheet [ 90 ], Conduction—heater bands are mounted on the external surface of the die to heat the entire workpiece during ISF [ 91 ], Electricity—an electric current is used to heat the workpiece at the actual location of forming [ 77 , 92 , 93 ], Friction—material is heated due to frictional forces between the rotating tool and the fixed sheet [ 94 , 95 , 96 ]. …”

“…Friction—material is heated due to frictional forces between the rotating tool and the fixed sheet [ 94 , 95 , 96 ].…”