Tool and Tool Guide Design for Shear Cutting of Tubes

―Research on Shear Cutting of Thin-walled Square Tubes (2nd report)―

Abstract

A cutting tool is designed for the shear cutting of thin-walled tubes. Cutting force is evaluated by changing cutting parameters such as shear strength, wall thickness, punch top angle and side length, and is found to be similar to that used in the shearing of flat sheets with a shear angle. Surface strain is observed during cutting and is found to vary depending with cutting conditions, which affects punch distortion. To prevent this deformation, the gap between the punch and the guide should be zero, which cannot be easily achieved using a conventional punch guide. To achieve zero clearance easily, a new guide using rollers is developed. This roller guide is always in contact with the punch, which is also available for cutting rectangular tubes. When designing the punch guide without distortion of the punch, a punch with a thickness of 2mm for a wall thickness of 2.3mm and another punch with a thickness of 1mm for a wall thickness of 1.6mm are available. This leads to a reduction in the amount of cut scraps.