US2897585A - Method for removal of the current supply bolts from aluminum electrolysis furnaces - Google Patents

Description

Aug. 4, 1959 G. BODEWEIN 2,897,585 METHOD FOR REMOVAL OF THE CURRENT SUPPLY BOLTS FROM ALUMINUM ELECTROLYSVIS FURNACES Filed June 6, 1955 Inventor:

United States Patent IVIETHOD FOR REMOVAL OF THE CURRENT SUP- PLY BOLTS FROM ALUlViINUM ELECTROLYSIS FURNACES Gerhard Bodewein, Grevenbroich-Orken (Lower Rhine), Germany, assignor to Vereinigte Aluminium-Werke A.-G., Bonn, Germany, a corporation of Germany The invention relates to the anodes used in aluminum electrolysis furnaces. In the operation of these furnaces continuously operative anodes made of pre-burnt artificial carbon blocks are used which must be continuously replaced according to their consumption.

With this purpose in view lateral cylindrical or conic bolts generally made of iron are employed, which enable the support of the anodes and the supply of current to the same. The anodes are lowered into the electrolyte in conformity with their consumption; they are submerged with their lower part into the molten electrolyte having a temperature of about 950 C.

The bolts are entered into the upper portion of the anode block and removed from the same as soon as they reach the vicinity of the hot electrolyte and the danger of their destruction arises.

The removal of these bolts from the anodes is difiicult since the latter in the moment of this removal are quite near to the electrolyte and are heated to approximately 700 C. Moreover, it must be kept in mind that these bolts are mostly held in a downwardly inclined direction towards the anode.

These bolts are for their removal pulled from the anodes by hydraulic means or by Withdrawal devices provided with screw threads; attempts have been made to apply rotation to the bolts during their removal.

The devices are based upon the fact that the withdrawal devices for the bolts are supported upon the anode itself, the latter serving as an abutment; however, the known bolt removal methods and devices meet'with great difficulty mainly caused by the inclined position of the bolts and the high operating temperature which exerts an enormous strain upon the service personnel.

It is the main object of this invention to eliminate these difiiculties and to facilitate the removal of the anode holding bolts from the anodes of the aluminum producing electrolysis furnaces.

It is also an object of the invention to facilitate the cooperation of the service personnel.

With these objects in view the invention will now be described morev in detail and with reference to the attached drawing showing a vertical sectional view of the 7 aluminum electrolysis furnace and its bolt removal device.

As apparent from the drawing, a current contact forming bolt 3 is entered into the anode 1, the latter reaching into the molten electrolyte 2. A hollow drill 4 is entered upon and surrounds the contact bolt 3 to be removed from the anode 1. The drill 4 upon rotation serves to produce a cylindrical gap surrounding contact bolt 3. The tubular drill 4 at its operative end preferably provided with hard cutters, not shown in the drawing; the drill is actuated by motor 5, which may be driven by compressed air or electricity. The device can be operated without difficulty and the hollow drill 4 is automatically centered. Cooperation by the service personnel is restricted to the forward movement of the drill 4. The drill creates after a few minutes of revolution a bore having a width of 5 to 10 millimeters around the contact bolt 3, which permits an easy removal thereof from the anode 1.

The device is for its manipulation provided with handles 6, and the tubular drill 4 with openings 7 for the removal of the powder created by the rotation of the drill 4.

The application of the device is, as follows:

The hollow drill 4 is pushed over the protruding end of bolt 3 and set in rotation by the motor 5. The rotating tubular drill 4 is guided by the contact bolt 3 and therefore needs only to be pressed forward to enter into the anode 1 until the depth of the contact bolt 3 is reached and the latter is completely freed. The produced fines are removed through openings 7 of the tubular drill 4.

It will be apparent to those skilled in the art that the novel principles of the invention disclosed herein in connection with specific exemplification thereof will suggest various other modifications and application of the same. It is accordingly desired that in construing the breadth of the appended claim they shall not be limited to the specific exemplification of the invention described herein.

Having thus described the invention, what I claim as new and desire to be secured by Letters Patent is as follows:

In a method for withdrawing a bolt having a portion embedded in a pre-burned continuous anode of an aluminum electrolysis furnace with the aid of a hollow drill driven by an electric motor having arms, the steps comprising selecting a hollow drill having an internal diam eter slightly larger than said bolt, whereby the drill may be telescoped over the bolt and be guided and centered by the bolt, positioning said drill to surround said bolt and driving said drill with said motor, and muscularly feeding said drill by axially directed pressure applied to said arms, whereby said drill will remove all of the material surrounding throughout the external periphery of said bolt thereby freeing the bolt from its embedment, applying the muscular feed forces and simultaneously a mo mentum compensating force to the arms in such a relationship that an average adult muscular force will be suflicient to counteract the rotary momentum generated by the drilling and transmitted to the arms, and subsequently manually removing the bolt freed from its embedment.

References Cited in the file of this patent UNITED STATES PATENTS

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