A novel approach for temperature control in ISF supported by laser and resistance heating

Abstract

Aeronautical applications often require small batches of large-scale sheet metal parts made from titanium and its alloys. Due to the low formability of titanium at room temperature, warm forming processes are necessary. Incremental sheet metal forming (ISF) is suitable for production of prototypes and small batches as well as large-scale parts. A short review of the experimental work done by international scientists in the field of warm ISF including stationary and moved temperature sensors will be presented mostly applied from the backside of the sheet metal. The present paper shows a new approach for a tool setup including a thermocouple inside of the tool. Hence, the sensor for temperature measurement was moved with the forming zone. Furthermore, a suitable closed loop control including a PID controller will be presented. The characteristics of the controller will be discussed. By means of two different warm ISF processes (ISF with resistance heating and laser-assist ed ISF), the applicability of the developed setup will be analysed and evaluated. It will be shown that the experimental setup is capable to ensure minimal temperatures needed to ensure adequate formability of Ti grade 5

Development of novel tools for electricity-assisted incremental sheet forming of titanium alloy

“…Various methods of heat generation in ISF have been reported including by using hot air blowers [1], conduction with a forming chamber [2], radiation by a laser beam [3][4][5][6], friction through tool rotation [7][8][9] or Joule heat by DC current [10][11][12][13][14].These technologies greatly enhanced the ISF capabilities in fabrication of lightweight alloys.…”

“…The tool may be made of various materials e.g. tungsten carbide [3,4,[10][11][12], die steel [5,6], high speed steel [7,13], H13 hot work steel [8], air-hardened D2 [9] and BOHLER K100 tool steel [14]. In some cases, wear-resistant or frictionreduction coating may be applied to the tool tip [3][4][5][6].…”

The Development of Incremental Sheet Forming from Flexible Forming to Fully Integrated Production of Sheet Metal Parts

“…titanium or magnesium alloys with a low formability at room temperature, heat-assisted ISF variants were developed, such as laser-assisted ISF by Duflou et al (2007) and Göttmann et al (2011), or ISF with resistance heating, see e.g. Göttmann et al (2012). These variants are also hybrid processes, whose set-up and control is much more involved than for conventional ISF.…”

Enhancement of process capabilities in electrically-assisted double sided incremental forming

“…In this process, a laser beam is employed to locally heat the sheet. Göttmann et al [12] also developed a hot ISF system by integrating a coaxial rotating optics to the ISF system. This laser-assisted ISF process has many advantages such as well controlled heating zone and temperature.…”

“…Ambrogio et al [16] further investigated this approach by quantifying the heat supplement respecting to the forming parameters. Göttmann et al [12] try to control the forming temperature by adjusting the input current. In the E-ISF process, surface finish and geometric accuracy are the two major problems due to the extreme high temperature at local area.…”