Initial situation:

Compensation of thermal warping during welding

It is well known that thermal warping of welded components is caused by the heat generated in the course of the welding process. Deviations of the welding path are possible in all three directions, so that the process does not take place at the optimum position of the gap, and also the geometrical shape of the object finally may change. This problem results in reduced stability, rework cost and even rejections. Remedy by inline welding seam correction on the basis of QuellTech laser scanners proves to be a meaningful approach.

Particular challenges

In classical systems weld seam correction is established by means of mechanical guide pins – but these items are often subjected to wedging or break, as the width of the gap, due to the thermal warping and distortion, is not constant. Precise adaptation of the welding current is difficult, because the mechanical welding guide does not deliver height information. The same holds for the guide pins: Due to the absence of transmitted geometrical data, welding current, travel speed and wire feed cannot be adapted to the circumstances, e.g. a modified gap width. As manual welding in industrial application is meanwhile considered to be obsolete, the stringent quality requirements for automated processes must be met. In recent applications, sensor equipment to be integrated to 100% inline is mandatory.

QuellTech solution

The QuellTech Seamtracking solution is based on 2D Laser Line Sensors, which inline record the geometrical and position data in X, Y and Z immediately in front of the process. QuellTech has furthermore developed a seam tracking software for analysis of captured data and transmission of correction values directly to robot and weld controller. The customer is free to configure his proper solution by means of the QuellTech modules, select a convenient laser wave length and laser power class. Furthermore, the sensors may be immunized against process light. For use on glowing metal surfaces, coolers are available. Laser scanner can be protected from spatter by easily exchangeable protection windows. QuellTech laser scanners are able to cover different ranges from zero gap seams up to extended multilayer weldments with a gap width above 100 mm. Solutions are available even for extreme deep gap geometries.

Benefits for clients and users

Thanks to the modular design, the QuellTech seam tracking solution offers a maximum of flexibility for users. For each welding process, an optimum configuration can be found, taking into consideration robot type, seam geometry and available space. Note that universal solutions often entail technical compromise limiting the capacities of the system. Deep gap tracking for pipeline welding for example cannot be established on the basis of a standard sensor. Therefore a large selection of particularly tailored configurations is comprised in the product portfolio of QuellTech.

A further benefit of QuellTech sensors is their small form factor, so that even in the case of narrow spaces, a powerful solution can be integrated. In the case of difficult access to a gap, the beam path can be adapted by deflection mirrors. Instruments with very high resolution are available as well, intended for example for seam tracking of zero gaps or very small welding or soldering seams.