Automatic machine for the production of single, double and triple chains already welded in the machine. This is a very versatile machine, with possibility of changing from curb to cable by means of a simple quick mechanism or from right to left curb, so as facilitating the production of two chains with identical pitch, suitable to the subsequent coupling in Bismark. The new, patented welding system allows an evenly distributed welding over 100% of the wire section, wire lubrication, reduction in gas consumption, longer life of the nozzle and the use of a simple, efficient welding nozzle cleaner, which ensures considerable autonomy. The machine comes complete with the second airblower, chain density sensor, electronic speed regulator with brake, electronic wire stretcher, electronic darkening screen and adjustable halogen lamp.