During the production of large pipes using a bending press, a gap remains between the longitudinal edges of the bent steel plate. With the Graebener continuous root tacking machine, the gap can be ideally adjusted before tacking the open-seam pipe. For this purpose, the pipe ends (longitudinal edges) are pushed together in a controlled way.
The pipe is run through the machine and is guided by rollers in all four directions. The upper and lateral rollers can be adjusted by hydraulic cylinders. The rollers are adjusted against each other so as to push the longitudinal edges of the open-seam pipe together. Hence, an accurate and optimum tack-welding process is guaranteed.
The welding gap is detected using a 2D laser scanner which processes the data accordingly. This leads to a constant gap welding which is an ideal basis for the subsequent continuous tacking process.
Machines for diameters from 280 to 2,134 mm (11 to 84 inches) are available.