Metallurgical apparatus – Means treating a continuum of work – With heating means
Patent
1992-03-09
1993-10-12
Kastler, Scott
Metallurgical apparatus
Means treating a continuum of work
With heating means
266103, C21D 596
Patent
active
052518817
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to methods and devices for thermally treating metal wires. Such methods and devices permit, for instance, the perlitization of steel wires so as to obtain a fine perlitic structure at a high speed, for instance at least equal to 15 m/second.
From SU Patent A-1 224 347, it is known to effect a perlitization treatment by passing a steel wire over smooth capstans placed in the ambient air so as to effect this treatment at a substantially higher speed than in a conventional lead patenting installation and without having the drawbacks of said lead technique which reside, in particular, in the dangers to health and the protection of the environment. Experience shows that the method described in that patent leads to the obtaining of products having a definitely poorer value in use than that which can be obtained with lead patenting. As a matter of fact, the cooling curve contains a substantial area of recalescence, for example a rise in temperature of 50.degree. C. for wires having a diameter of 3 mm. This substantial recalescence is due to the poor heat transfer coefficient between the wire and the capstan, which leads to a large difference in temperature between the wire and the capstan when the thermal power peak caused by the transformation of austenite into perlite takes place. Now, the presence of recalescence above 20.degree. C. during the heat treatment does not make it possible to obtain a high value in use of the wires, particularly when they are of large diameters.
European Patent Application A-275 864 describes a method for the heat treatment of metal wires by passing them over disks having grooves within an enclosure in which a protective gas is contained, the heating of the wires being obtained directly by irradiation.
U.S. Pat. No. 2,965,368 describes a method for the heat treatment of metal wires by passing them through grooves of capstans which are heated on the inside, the wires being reeved crosswise on these capstans in contact with a protective gas.
SUMMARY OF THE INVENTION
The object of the invention is to propose a method and an apparatus which permit the thermal treatment of a metal wire by passing the wire over capstans so as simultaneously to have a high speed of passage of the wire and a good thermal exchange between the wire and the capstan.
Accordingly, the invention relates to a method which permits the thermal treatment of at least one metal wire by means of capstans, in which the wire is passed over at least two heat-conducting capstans having grooves, the wire being reeved, crossed in these grooves, the width of the grooves being slightly greater than that of the wire, a gas in the grooves being in contact with the wire and the capstans; this method being characterized by the following features: arranged between the capstans and at least one part, this gas being in contact with the capstans and the part, said heat-conducting part being located outside the capstans, by circulating a heat-exchange fluid other than the gas in contact with the part so that heat exchanges take place, on the one hand, between the gas and the part and, on the other hand, between the part and the fluid; adjusted as a function of the thermal treatment to be carried out.
The invention also relates to a device which permits the thermal treatment of at least one metal wire by means of capstans, the device having at least two heat-conductive capstans with grooves, the device furthermore having means which make it possible to pass the wire in the grooves of the capstans, the wire being reeved, crossed in these grooves, the width of the grooves being slightly greater than that of the wire, and a gas, within the grooves, in contact with the wire and the capstans; the device being characterized by the following features: these means comprising: in contact with the part; the capstans and the part; hand, between the gas and the part and, on the other hand, between the part and the fluid; layer of gas between the capstans and the part as a function of the
REFERENCES:
patent: 2965368 (1960-12-01), McIlvried
patent: 3021128 (1962-02-01), Jonason
patent: 4012028 (1977-03-01), Dunaevsky et al.
patent: 4062528 (1977-12-01), Olivero
patent: 4919395 (1990-04-01), Ritter et al.
Compagnie Generale des Etablissements Michelin - Michelin & Cie
Kastler Scott
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