Laser bending can result from the localised heating of a material. There are three mechanisms for bending, temperature gradient (TGM), buckling and upsetting. Each method is determined by the gradient of compression created by the distribution of heat through the material’s thickness. Laser forming is an asymmetric process with many variables. Much effort has been made to understand the mechanisms and variables in isolation. The understanding of the mechanisms and the effects of process parameters are the vehicle by which forms can be investigated. The most influential factors of forming are; line configuration, part geometry and sequence. This paper aims to explore these variables in order to define a range of forming abilities for tube.
Tubes can be manipulated by all three mechanisms, however the most potent method is upsetting. Upsetting generates homogenous compression through the material’s thickness, which results in a shortening of a given section This method has been mostly used for forming spatial parts i.e.: bowls, or to bend tubes about a single axis. Principles for tube forming can be developed with support from sheet bending knowledge: process, line configuration and sequence techniques. Selective bending around the section, can create complex profiles with a fluidity difficult to achieve by other methods and arduous by hand. When trying to create a pattern to produce a specific form there is a need to translate the physical loss into compression of the material. This negotiates the required loss of surface area. Process knowledge can then be applied to derive a possible configuration and sequence.
The asymmetric quality of the process poses problems for sheet forming. The heating solution for a given shape is hard to determine, due to the prominence of the first bend, and its affect on the bending direction and efficiency of subsequent lines within the pattern. With tube forming work is along directional axes, and forming tends to be cumulative. This asymmetry has some positive advantages for tube forming, in that the cross plane compression can be manipulated by the process parameters to produce a volume of compression that equates to the required surface loss.