How to weld a chassis manually

1 MANUALLY OR AUTOMATED?

If the construction of a chassis (pipe cutting, bending and welding) was entirely manual in the past, in recent years, large companies have been able to invest in automated machinery. In particular, the welding is the “key step” in the realisation of the chassis, significantly affecting its performance, as well as its duration. Automated or “manual” welding are, currently, the two main approaches to manufacturing chassis. IPK, a company that manufactures the OK1 and Prague chassis, has returned to manual welding after a period in which it manufactured the chassis using an automated system.

2 PROS AND CONS

The reason why IPK is welding manually is mainly to have better control of each individual welding by its skilled workers, who can correct defects. Furthermore, according to IPK, welding using automated machinery resulted in poor quality consistency, due to current fluctuations that generated different intensities in the welding of tubes. These reasons, however, are disputed by those who use automatic welding, who, to the contrary, consider the fact of being able to have welding repeatability and consistency, with absolute precision thanks to the computerisation of the various phases, a strong point.

3 HAND WELDING, TUBE BENDING ROBOT

IPK believes in manual welding, but it uses automated machines for the phases before welding, such as cutting and, above all, the bending of tubes. The new IPK automated machinery allows absolute precision, with tolerance to a tenth of a degree in the bend. The system is electrically operated, and therefore excludes hydraulic systems that depend on oil temperature (colder at the beginning of processing, especially in winter months). The machine has an energy recovery system (a bit like electric and hybrid cars), it works on 11 axes and several masks (female housings for tubes) for tubes with a diameter of 28-30-32 mm. A core is used during the processing, in other words a cylindrical element for filling tubes, of variable diameter depending on the size of the tube, which is positioned before the bending point and avoids the tube being crushing.
The new machine can achieve the same bending even when the tube material changes, recognising the elasticity of the steel that is used. It is a closed gripper system, that is, the tube to be bent is gripped along its length, but pushed from the end, so as not to strain the material.