TWI Industrial Member Report Summary 873/2007
By S J Mulligan
Vision-based systems are employed industrially for remote monitoring of arc welding processes in mechanised applications. The main difficulty encountered by operators is the high intensity of light emitted by the arc, which prevents good visibility of the metal transfer and weld pool and makes automated control of the process difficult.
High-speed video systems are too expensive for the majority of industrial users. TWI, in cooperation with the University of Liverpool, has developed a vision system for monitoring arc welding processes based on a low-cost CMOS camera. The total cost of the vision system equipment is approximately £3,000 (July 2006 prices), excluding the cost of the illumination equipment. The system uses a narrow bandpass filter that is tailored to the illumination source, and control of aperture and exposure settings to limit the amount of arc light reaching the camera sensor.
This report describes a programme of work carried out to evaluate the performance of the low-cost vision system using a continuous wave (CW), high power neodymium-doped yttrium aluminium garnet (Nd:YAG) laser source for illuminating the weld pool. The system was used to observe the tungsten inert gas (TIG) and metal active gas (MAG) arc welding processes.
- Evaluate the performance of a low-cost vision system using CW Nd:YAG laser illumination.
- Observe weld pool and metal transfer phenomena in TIG welding.
- Observe metal transfer in MAG welding.