DE3319769C1

DE3319769C1 - Compound electrode for arc furnaces

Info

Publication number: DE3319769C1
Application number: DE19833319769
Authority: DE
Inventors: Luciano 4130 Moers Ambrosi; Friedrich Dr.-Ing. 4020 Mettmann Nordmeyer; Ludger Dr.-Ing. 4300 Essen Zangs; Klaus Dr.-Ing. 4044 Kaarst von Ploetz
Original assignee: Mannesmann AG
Current assignee: Vodafone GmbH
Priority date: 1983-05-27
Filing date: 1983-05-27
Publication date: 1984-11-22

Abstract

In a compound electrode for arc furnaces, which comprises a metallic, cooled upper electrode section and at least one lower graphite electrode section, the sections are mechanically joined by a nipple and the electrical connection is made through the end faces of the electrode sections. In order to construct a nipple joint so that it can withstand high tensile and compression loadings, high temperatures and high thermal shock stresses and has a low coefficient of thermal expansion, it is proposed that the nipple (2) is composed of ceramic materials having an Al2O3 content of more than 90%, a density of about 3 kg/dm<3> and a thermal conductivity of less than 30 W/mK. <IMAGE>

Description

Patentansprüche: 1. Zusammengesetzte Elektrode für Lichtbogenöfen, die aus einem metallischen, gekühlten oberen Elektrodenabschnitt und mindestens einem unteren Elektrodenabschnitt aus Graphit besteht, wobei die mechanische Verbindung der Abschnitte durch einen Nippel und die elektrische Verbindung durch die Stirnflächen der Elektrodenabschnitte erfolgt, d a -durch gekennzeichnet, daß der Nippel (2) aus elektrisch isolierendem keramischem Werkstoff mit einem A12O3-Gehalt von mehr als 90% besteht.Claims: 1. Compound electrode for electric arc furnaces, that of a metallic, cooled upper electrode section and at least a lower electrode section made of graphite, the mechanical connection the sections through a nipple and the electrical connection through the end faces of the electrode sections takes place, d a - characterized in that the nipple (2) Made of electrically insulating ceramic material with an A12O3 content of more than 90%.

2. Zusammengesetzte Elektrode nach Anspruch 1, dadurch gekennzeichnet, daß der Nippel (2) in den unteren Elektrodenabschnitt (1) eingeschraubt ist und die mechanische Verbindung zwischen den Elektrodenabschnitten durch eine im Inneren des oberen Elektrodenabschnittes angeordnete, den oberen Nippelkonus umschließenden Aufnehmer (3) erfolgt, der mit einer Zugvorrichtung (5, 6, 11) in Eingriff steht und in einem Führungsring (7) des oberen Elektrodenabschnittes ($) geführt ist. 2. Composite electrode according to claim 1, characterized in that that the nipple (2) is screwed into the lower electrode section (1) and the mechanical connection between the electrode sections by an inside of the upper electrode section, which surrounds the upper nipple cone Sensor (3) takes place, which is in engagement with a pulling device (5, 6, 11) and is guided in a guide ring (7) of the upper electrode section ($).

3. Zusammengesetzte Elektrode nach den Ansprüchen 1 und 2, dadurch gekennzeichnet, daß der Nippel (2) in den Aufnehmer (3) eingeschraubt ist Die Erfindung betrifft eine zusammengesetzte Elektrode für Lichtbogenöfen gemäß dem Oberbegriff des Patentanspruchs 1. 3. Composite electrode according to claims 1 and 2, characterized characterized in that the nipple (2) is screwed into the transducer (3). The invention relates to a composite electrode for electric arc furnaces according to the preamble of claim 1.

Aus der DE-OS 27 39 483 ist eine derartige zusammengesetzte Elektrode bekannt, deren oberer Abschnitt - der aus Metall besteht - gekühlt ist. Dieser bleibende Abschnitt ist mittels eines Nippels mit dem Graphitelektrodenabschnitt verbunden, wobei dieser als doppelter Konus ausgebildet und in beide Abschnitte eingeschraubt ist. Der Nippel besteht aus demselben Material wie der untere Elektrodenabschnitt, also aus Graphit. Im Inneren des oberen Elektrodenabschnittes wird die Kühlflüssigkeit so geführt, daß der Nippel ebenfalls ausreichend gekühlt wird. From DE-OS 27 39 483 such a composite electrode is known whose upper section - which consists of metal - is cooled. This permanent one Section is connected to the graphite electrode section by means of a nipple, this being designed as a double cone and screwed into both sections is. The nipple is made of the same material as the lower electrode section, So made of graphite. The cooling liquid is inside the upper electrode section guided so that the nipple is also adequately cooled.

Diese Kühlung ist von besonderer Bedeutung, da es insbesondere im Bereich der Annippelung oft zu Schachtelbrüchen kommt, die den Ofenbetrieb sehr schädigen. This cooling is of particular importance because it is particularly important in the The nipple area often results in box breaks, which greatly affects the operation of the furnace damage.

Aufgabe der Erfindung ist es, die Nippelverbindung so auszubilden, daß sie hohen Zug- und Druckbelastungen, hohen Temperaturen und Temperaturwechselbeanspruchungen standhalten kann, sowie einen geringen Wärmedehnungskoeffizienten aufweist. The object of the invention is to design the nipple connection so that they are high tensile and compressive loads, high temperatures and thermal shock loads can withstand, and has a low coefficient of thermal expansion.

Gelöst wird diese Aufgabe erfindungsgemäß durch die im Kennzeichen des Patentanspruchs 1 angegebenen Merkmale. This object is achieved according to the invention by means of the characteristics of claim 1 specified features.

Eine vorzugsweise Weiterbildung ergibt sich aus den A preferred development results from the

Claims

Subclaims.

The invention uses a ceramic nipple, i.e. an electrical one insulating material. The prerequisite for this training of the nipple was previously made statement that the optimal current flow at the electrodes does not go over the nipple, but over the close-together end faces of the electrode sections.

The previous nipples consisted of electrically conductive materials such as Graphite or made of metal. Since with the electrical conductivity also the thermal conductivity speed increases, these nipples - as described above - had to be strongly cooled. In the nipple according to the invention made of ceramic material, which also does not go through Current flow is heated immediately, this is no longer necessary, so that the entire Structure of the electrode, in particular that of the remaining section, is significantly simplified can be.

The invention is intended below with reference to that shown in the drawing Embodiment are explained, this being a longitudinal section through the Shows transition area of the electrode sections.

The nipple 2 is with the electrode 1 and the metal receiving part 3 each connected via a conical thread in a form-fitting and force-fitting manner. Also the outside of the transducer 3 is conical in the example shown.

Via the pull rod 11, the claws 5, the transducer 3 and the nipple 2, the electrode 1 is firmly attached to the end face of the water-cooled electrode section 8 tightened.

Due to the poor thermal conductivity of the ceramic, there is a need for cooling of the receiving part 3 is no longer required in intensive form for reasons of strength, because the ceramic acts like an insulation between electrode 1 and receiving part 3. In the example shown, only simple cooling fins 10 are provided.

The cooling water flows through the space 9, which is between the double-walled Sheath of the metal electrode 8 extends.

The gripping claws 5, which are guided in the guide ring 7, attack the pulling head 4 of the transducer 3. They are articulated with a claw head 6, to which the pull rod 11 is connected.

By pulling the rod 11 axially, the transducer 3 is connected to the nipple 2 as well as the electrode 1 pulled up.

The contact between the electrode 8 and the graphite electrode 1 comes about on the support surface 12.

The nipple consists of a ceramic material, namely a Refractory concrete with an Al203 content of more than 90% and a density of approx. 3 kg / dm3 and a thermal conductivity less than 30 W / mK.