Formability of Materials with Small Tools in Incremental Forming
- PDF / 2,665,178 Bytes
- 9 Pages / 595.276 x 790.866 pts Page_size
- 97 Downloads / 226 Views
Chinese Journal of Mechanical Engineering Open Access
ORIGINAL ARTICLE
Formability of Materials with Small Tools in Incremental Forming Hongyu Wei1, G. Hussain2*, X. Shi3, B. B. L Isidore4, Mohammed Alkahtani5,6 and Mustufa Haider Abidi6
Abstract Single point incremental forming (SPIF) is an innovative sheet forming process with a high economic pay-off. The formability in this process can be maximized by executing forming with a tool of specific small radius, regarded as threshold critical radius. Its value has been reported as 2.2 mm for 1 mm thick sheet materials. However, with a change in the forming conditions specifically in the sheet thickness and step size, the critical radius is likely to alter due to a change in the bending condition. The main aim of the present study is to undertake this point into account and develop a relatively generic condition. The study is composed of experimental and numerical investigations. The maximum wall angle (θmax) without sheet fracturing is regarded as sheet formability. A number of sheet materials are formed to fracture and the trends correlating formability with normalized radius (i.e., R/To where R is the tool-radius and To is the sheet thickness) are drawn. These trends confirm that there is a critical tool-radius (Rc) that maximizes the formability in SPIF. Furthermore, it is found that the critical radius is not fixed rather it shows dependence on the sheet thickness such that Rc = βTo, where β varies from 2.2 to 3.3 as the thickness increases from 1 mm to 3 mm. The critical radius, however, remains insensitive to variation in step size ranging from 0.3 mm to 0.7 mm. This is also observed that the selection of tool with R < Rc narrows down the formability window not only on the higher side but also on the lower side. The higher limit, as revealed by the experimental and FEA results, diminishes due to excessive shearing because of in-plane biaxial compression, and the lower limit reduces due to pillowing in the bottom of part. The new tool-radius condition proposed herein study would be helpful in maximizing the formability of materials in SPIF without performing experimental trials. Keywords: Incremental forming, Critical tool-radius, Formability curve, Finite element analysis 1 Introduction Single point incremental forming (SPIF) is an innovative sheet-forming technique economically well suited for low batch production and prototyping. In fact, this process contrary to traditional press forming operations [1] does not employ dedicated set of tooling in order to perform three-dimensional shaping. The blank is held at the periphery in a clamping rig, and a simple sphericalend tool tightened in a spindle of CNC milling machine follows a predefined path to produce the target shape in a series of loops. These features render SPIF a very *Correspondence: [email protected] 2 Faculty of Mechanical Engineering, GIK Institute of Engineering Sciences & Technology, Topi 23460, Pakistan Full list of author information is available at the end of the article
flexible proc
Data Loading...
