Real‐time top‐face vision based control of weld pool size

Top‐face control of weld penetration in TIG welding is required for fully automated systems to overcome variations in the welding process and fixturing systems.

This paper presents a system based upon based on the real‐time vision measurement and control of the upper surface or “topface” weld pool size. The primary objective has been to demonstrate the feasibility of using vision‐based image processing to provide measurements and the subsequent control of upper bead weld geometrical properties during the weld formation or molten phase and correlate this to the backface weld bead size.

Vision based measurement of the upper surface of the weld pool can be used, in real‐time, to control the weld pool size. This allows more uniform weld penetration to be achieved in the presence of disturbances.

The system requires that the pool edges can be accurately identified using a correlation method. This requires images with good contrast between the weld pool and the workpiece.

The system is applicable to both continuous and pulsed TIG welding.

A novel reference feature correlation‐based image analysis algorithm has been developed that may be configured to operate with a number of different welding processes. The issues of system integration, i.e. interfacing the system with legacy welding equipment are also discussed.