Verfahren zur Sicherung der Schraubverbindung zwischen Kohle- oder Graphitelektroden

摘要

In a method of producing a screw connection to a carbon or graphite electrode which is resistant against loosening, a moulding comprising 20 to 95% of a refractory, inflatable, heat-hardening and cokable resin and 80 to 5% fillers is provided in a bore or recess in a threaded nipple of the electrode or in a member into which the nipple is screwed, said recess being lined with a thin, insulating layer, for example of paper, and the nature of the resin being such that the moulding expands on heating to produce a resilient, locking engagement between the said member and the said nipple. Fig. 1 shows a longitudinal section through a screw connection between an electrode and an electrode socket. Screw-threaded nipple a is engaged in is placed in a recess in a, the moulding consisting of phenol-Novolak hexamethylene tetramine resin and finely ground fillers, e.g. graphite, coke and/or silicon carbide, the mixture having been homogenized in a dry mixer before pressing. Lining d is of paper. Alternatively, the mixture may be moistened with solvent, e.g. methyl or ethyl alcohol, homogenized and kneaded and placed in the recess before being shaped. Leavening agents and plasticizing agents, e.g. pitch, may be added to the pressed or kneaded mixture. Further adhesiveness may be supplied by coating the free and face of the moulding with viscous resin, say phenol-resol or pitch. In Fig. 2 the connection has been heated, moulding c enlarging and growing against the wall of b, but still having play relative to a, owing to gap e resulting from the coking of d.