Development and Evaluation of Curved Synchronous Die-Less Spinning(Machine Elements, Design and Manufacturing)

Products formed by metal spinning have been inherently limited to straight-axis and circular-sectional shapes. In this study, we succeeded in making curved-axis and non-axisymmetric shells by synchronizing the roller motion in the axial and radial direction with the rotation of the spindle axis, and without using forming dies. A hemi-spherical head tool and straight/inclined-shape mandrels are designed for a use of general purpose. A numerically-controlled spinning machine moves the tool along a spiral trajectory on the surface of the product. The trajectory is calculated from the desired shape considering contact with the tool. Curved cones up to 60 degree bended and curved non-axisymmetric shapes are experimentally formed from aluminum sheet. An equation is proposed to estimate the wall thickness of products, based on curved shear deformation model. It is verified that the model nearly coincides with measured thicknesses of products. Twisting distortion of the product shape is suppressed by switching direction of the spindle rotation alternately.