This invention relates to a method for teem-welding metals, preferably light metals, particularly aluminium and its alloys. The invention further relates to a nozzle arrangement for use in an embodiment of the method.
In certain industries, for example in the electrolytic smelting of aluminium, the series welding of workpieces of comparatively large dimensions is an important cost factor. Of particular interest in this connection is the joining of busbars, cables or flexible electric conductors of large cross-section to carry the high currents which are used in electrolytic smelting.
A method previously in common use for such teem-welding is the through-flow method, in which the molten metal which is used for the teem-welding process, is caused to flow through the casting mould long enough to achieve the desired melting of the workpiece or workpieces. This method required a very much larger quantity of metal than that needed for the actual weld. For this reason, the method is laborious in practice, and further, costly on account of the large volume of metal which has to be melted and handled, including its transportation before and after the making of the teem-weld. In spite of this, teem-welding by the through-flow method has been very widely used for the purposes under discussion herein.
A second well-known method which should also be mentioned, is the so-called thermit welding method. This is an exothermic welding process, and is based on the fact that the metal is melted by means of the reaction heat which is developed on the ignition of a special welding powder mixture. A highly overheated melt results and is introduced into the casting mould which is usually made of graphite, and which surrounds the ends of the workpieces which are to be joined together. This method is used, for example, for joining railway lines etc., but is fairly expensive on account of the special powder mixture used.