Experimental investigations and optimization of forming force in incremental sheet forming

Abstract

Incremental sheet forming process has been proved to be quiet suitable and economical for job and batch type production, which exempts expensive and complex tooling for sheet forming. Investigation of forming forces becomes important for selecting the appropriate hardware and optimal process parameters in order to assure perfection and precision of process. Moreover, lack of available knowledge regarding the process parameters makes the process limited for industrial applications. This research paper aims at finding out effects of different input factors on forming forces in single-point incremental forming (SPIF) process. For operation sustainability and hardware safety, it becomes critical to optimize forming forces for a given set of factors to form a particular shape. In this study, optimization of input factors has been performed to produce conical frustums with helical tool path using Taguchi analysis as design of experiment (DOE) and analysis of variance (ANOVA). The optimal experimental conditions for forming forces have been calculated as sheet thickness (0.8 mm), step size (0.2 mm), tool diameter (7.52 mm), tool shape (hemispherical), spindle speed (1000 rpm), feed rate (1000 mm/min) and wall angle (50 o). Effects of tool shape and viscosity of lubricants have also been investigated. An intensive understanding of the mechanism of forming forces has been presented, which shows that force trend after peak values depends upon instant input factors that can be categorized as a safe, severe and crucial set of parameters.

Forming force in incremental sheet forming: a comparative analysis of the state of the art

“…According to forming methods, ISF is categorized as single-point incremental forming (SPIF) or negative incremental forming, two-point incremental forming (TPIF) or positive incremental forming, double-sided incremental forming (DSIF) and hybrid forming [7,8]. SPIF or negative incremental forming ( Fig.…”

“…2a) is a truly die-less forming. The lower surface of the sheet does not contact any kind of support during this process, and different types of stress-strain patterns are observed in the deformation of sheet [8,9]. In the DSIF process ( Fig.…”

“…In the past few years, substantial research has been carried out by researchers but still there is a lack of intensive understanding of the mechanism of forming forces in the ISF process. The relation between the process parameters and forming force plays a very crucial role in optimizing the process for better response qualities [8]. Moreover, investigation of the forming forces is one of the most important ways to understand the deformation mechanism of the ISF process.…”

“…The force components F x , F y and F z along x, y and z directions, respectively, can be measured with the help of force dynamometer or load cell. In the literature, table-type force dynamometer [7,8, has mostly been used which is mounted between the machine bed and ISF fixture. The force exerted by the forming tool on the component can be simply measured by a load cell, and the measured data can be recorded with the help of data acquisition system, charge amplifier and PCbased environment (Fig.…”

“…The tool trajectory design is very important which has a direct impact on the forming force and processing time in the ISF process. Tool path determines the feasibility of safe forming of the components [7,8]. Commercial computeraided manufacturing (CAM) packages offer different types of tool paths for manufacturing applications.…”