Oblique/Curved Tube Necking Formed by Synchronous Multipass Spinning
Advanced Manufacturing Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba 305-8564, Japan
Daitoh Spinning Co. Ltd., Oura-Town 370-0603, Japan
Author to whom correspondence should be addressed.
Metals 2020, 10(6), 733; https://doi.org/10.3390/met10060733
Received: 28 April 2020 / Revised: 25 May 2020 / Accepted: 28 May 2020 / Published: 2 June 2020
(This article belongs to the Special Issue Latest Hydroforming Technology of Metallic Tubes and Sheets)
In this paper, we propose a method of forming a tube into an oblique/curved shape by synchronous multipass spinning, in which the forming roller reciprocates in the radial direction in synchrony with the rotation angle of the spindle while the roller moves back and forth along the workpiece in the axial direction to gradually deform a blank tube into a target shape. The target oblique/curved shape is expressed as a series of inclined circular cross sections. The contact position of the roller and the workpiece is calculated from the inclination angle, center coordinates, and diameter of the cross sections, considering the geometrical shape of the roller. The blank shape and the target shape are interpolated along normalized tool paths to generate the numerical control command of the roller. By this method, we experimentally formed aluminum tubes into curved shapes with various radii of curvature, and the forming accuracy, thickness distribution, and strain distribution are examined. We verified that the curved shapes with the target radii of curvature can be accurately realized.