METODO ED APPARATO PER LA CREAZIONE DI UNO STRATO SUPERFICIALE CON COMPOSIZIONE ALTERNANTESI

A method comprises feeding two or more, if necessary, alloying materials and simultaneously changing the ratio thereof. The ratio of the alloying materials is changed at the moment of transition from one section to the other one having different composition, the ratio being changed to such extent that the length of the transition portion is as small as possible. The time of transition is determined depending on the weld pool volume, rate of surfacing, cross section of the layer being built up, amount of the alloying elements both the required and the real one. Determining the time of transition for carrying out the method of the invention is disclosed in term of a preferred embodiment. An apparatus for carrying out the method of the invention is characterized in that it includes an adder-differentiator link, a voltage limiter, a switching device and an aperiodical link. The aperiodical link is a simulator of the weld pool. It has an input connected to a control unit which controls the operation of an alloying material feeding device, and is connected through the switching device to the voltage limiter to receive an output signal proportional to the surfacing parameters. The aperiodical link is also connected with two outputs of a surfacing parameters regulating unit for providing an output signal of the voltage limiter in accordance with the surfacing parameters.