Copper contact jaw and method for production thereof

Abstract

The present application relates to a copper contact jaw (1) for an electrical smelting unit, which can be attached to an electrode carrying arm (2) of the smelting unit and via which an electrode of the smelting unit can be electrically conductively connected to the electrode carrying arm (2), having a main body (4) with a rear face (5) and an opposite front face (6), a first end face (9) and a second, axially opposite end face (10), and at least one first and one second side face (11a, 12a); two contact faces (7, 8) arranged on the front face (6) of the main body (4), which contact faces are mirror-symmetrical and extend axially along the main body (4); and a cooling channel system having a coolant inlet opening (13) and a coolant outlet opening (14) and a plurality of cooling channels (15) which extend axially and radially through the main body (4).

Description

[0001] The present invention relates to a copper contact jaw for an electrical melting unit, in particular an electric arc furnace, which can be attached to an electrode support arm of the melting unit and via which an electrode of the melting unit can be electrically conductively connected to the electrode support arm, as well as to a method for producing the copper contact jaw according to the invention.

[0002] Contact jaws of this type have long been known from the state of the art, for example from the Korean laid-open specification KR 200 441 093 Y1 or from the German laid-open specification DE 34 43 574 A1 as well as from the German laid-open specification DE 10 2004 005 051 A1.

[0003] Such contact jaws, made of pure copper, are manufactured by first preparing a rolled or forged copper blank and then machining it to create holes for water cooling. Due to the size of a contact jaw, which can, for example, be 750 mm long, 600 mm wide, and 150 mm thick, deep-hole drilling remains a technical challenge. For this reason, large drill diameters of at least 24 mm are currently used, with the holes typically being drilled into the contact jaw via the opposite end faces so that the holes meet in the center. The two openings can then be sealed by welding with a copper plug or using threaded plugs.

[0004] When welding copper, the material to be welded must typically be uniformly preheated to a temperature of approximately 600 °C, which is energy- and time-intensive. Temperatures exceeding 1200 °C then arise at the weld points, leading to local recrystallization of the microstructure and, consequently, a loss of the original hardness acquired by the forging or rolling process. Even sealing with threaded plugs or similar means cannot be guaranteed permanently due to the high ambient temperatures in the unit.

[0005] Against this background, the present invention is based on the object of providing a copper contact jaw for an electrical melting unit, in particular for an electric arc furnace, which is improved compared to the prior art, as well as a method for producing such a copper contact jaw which is improved compared to the prior art. Description of the invention

[0006] According to the invention, the object is achieved by a copper contact jaw having the features of patent claim 1 and by a method having the features of patent claim 9.

[0007] According to the invention, the copper contact jaw, which can be attached to an electrode support arm of the melting unit and via which an electrode of the melting unit can be electrically connected to the electrode support arm, comprises a base body with a rear surface, which usually faces an electrode arm, and an oppositely arranged front surface, which usually faces an electrode, a first end surface and a second, axially opposite end surface, which in the installed state then faces the melt in the melting unit, as well as at least a first and a second side surface; two contact surfaces arranged on the front surface of the base body, which are mirror-symmetrical to one another and extend axially along the base body;and a cooling channel system with a coolant inlet opening and a coolant outlet opening, as well as a plurality of cooling channels extending axially and radially through the base body, wherein the cooling system comprises at least ten individual cooling channels. Similarly, the method according to the invention for producing a copper contact jaw provides that, first, a forged or rolled copper contact jaw blank is provided, which comprises a base body with a rear surface and an oppositely arranged front surface, a first end surface and a second, axially opposite end surface, at least a first and a second side surface, and two contact surfaces arranged on the front surface of the base body, which contact surfaces are mirror-symmetrical to one another and extend axially along the base body;wherein a coolant inlet opening, a coolant outlet opening and a plurality of cooling channels running axially and radially through the base body are then introduced mechanically, preferably by means of deep hole drilling;

[0008] The cooling channel system, which comprises a coolant inlet opening, a coolant outlet opening, and a plurality of cooling channels running axially and radially through the base body, achieves improved heat dissipation due to the increased number of cooling channels. Furthermore, the cooling channels, due to their much smaller diameter compared to the prior art, can be placed closer to the highly stressed contact surfaces, thereby significantly improving their cooling effect. In terms of production technology, the copper contact jaw according to the invention no longer requires welding. This ensures that the material does not undergo recrystallization and thus retains the structure established during the forging or rolling process, thus ensuring longer service life. Secondly, a second mechanical processing step, including setup time, is eliminated, which also reduces production costs.

[0009] Further advantageous embodiments of the invention are specified in the dependent claims. The features listed individually in the dependent claims can be combined with one another in a technologically expedient manner and can define further embodiments of the invention. Furthermore, the features specified in the claims are further specified and explained in the description, where further preferred embodiments of the invention are presented.

[0010] The cooling system comprises at least ten, preferably at least twenty, more preferably at least thirty, even more preferably at least forty, and most preferably at least fifty individual cooling channels.

[0011] Advantageously, the plurality of cooling channels are formed in the base body and fluidically connected to one another in such a way that they can be supplied with a coolant via a single central coolant inlet opening and a single central coolant outlet opening.

[0012] According to the method according to the invention, the one to three large holes of at least 24 mm in diameter are replaced by a multitude of small, fluidically connected deep holes. The multitude of cooling channels ensures the required cooling water flow rate of, for example, 5000 L / h. Furthermore, the multitude of cooling channels, which are formed by a single-sided, open deep hole, allows them to be positioned in the copper contact jaw in such a way that the threaded plugs used to close the openings are not directly exposed to the radiant heat of a melt when the copper contact jaw is in use.

[0013] Preferably, each of the cooling channels has a diameter in the range of 4.0 to 16.0 mm, more preferably a diameter in the range of 5.0 to 14.0 mm, even more preferably a diameter in the range of 6.0 to 12.0 mm, and most preferably a diameter in the range of 6.00 to 10.0 mm. In a particularly preferred embodiment, the diameter of each deep hole and thus of each cooling channel is 8.0 mm.

[0014] In a further advantageous embodiment, the plurality of cooling channels is formed from a plurality of cooling channel groups, each of which extends axially or radially through the base body of the copper contact jaw. In this context, it is particularly preferred that each of the plurality of cooling channel groups comprises at least two, preferably at least three, more preferably at least four or more cooling channels. In a particularly preferred embodiment, each of the plurality of cooling channel groups comprises four cooling channels. By combining the plurality of cooling channels into individual groups, the manufacturing process can be further simplified, since several deep-hole bores can be created in a single work step.

[0015] In a further aspect, the present invention also relates to an electric melting unit, in particular an electric arc furnace, comprising an electrode support arm and a copper contact jaw according to the invention arranged on the electrode arm. Figure name

[0016] The invention and the technical environment are explained in more detail below with reference to the figures. It should be noted that the invention is not intended to be limited by the exemplary embodiments shown. In particular, unless explicitly stated otherwise, it is also possible to extract partial aspects of the facts explained in the figures and combine them with other components and findings from the present description and / or figures. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. The same reference numerals denote the same objects, so that explanations from other figures can be used as a supplement if necessary. They show: Fig. 1a / 1b shows an embodiment of the copper contact jaw according to the invention in a perspective view, Fig. 2 to 6 different sectional views of the Figure 1shown copper contact jaw, and Fig. 7 a variant of an electrode arm comprising the copper contact jaw. In the Figures 1a and 1b A variant of a copper contact jaw 1 according to the invention is shown in two different perspective views. The present copper contact jaw 1 consists of pure forged copper (99.98 wt.%) and is intended for use in an electrical melting unit, such as an electric arc furnace. Such a melting unit or the electric arc furnace can have one or more electrode support arms 2 (see Figure 7 ), to the distal end of which the copper contact jaw 1 is attached. An electrode of the melting unit, such as a graphite electrode, is electrically connected to the electrode support arm 2 via the copper contact jaw 1 and a fastening means 3. Usually, the Electrode (not shown) is fixed to the electrode support arm 2 via the fastening means 3.

[0017] As shown by the Figures 1 to 6As shown, the copper contact jaw 1 comprises a base body 4 with a rear surface 5 facing an electrode arm 2 and a front surface 6 arranged opposite the rear surface 5 and then facing the electrode. In order to achieve sufficiently high electrical contact between the electrode and the copper contact jaw 1, the front surface 6 has two contact surfaces 7, 8, each comprising a concave indentation, which extend axially along the base body 4 and are mirror-symmetrical to one another. It should be noted that, as an alternative to the embodiment variant shown here, the front surface 6 can also be formed by a continuous concave surface configuration. In this case, the two contact surfaces 7, 8 form an integral part of the latter.

[0018] Furthermore, the base body 4 comprises a first end face 9, a second end face 10 arranged axially opposite the first end face 9 and facing the melt in the installed state, as well as two side faces 11a, 11b, 12a, 12b.

[0019] According to the invention, the copper contact jaw 1 comprises a cooling channel system with a coolant inlet opening 13, a coolant outlet opening 14 and a plurality of cooling channels 15 which extend through the base body 4 in the axial and radial directions.

[0020] In the present embodiment, the coolant inlet opening 13 and the coolant outlet opening 14 are arranged in an upper third, viewed in the axial direction, and thus in a region facing the first end face 9, so that they are not directly exposed to the radiant heat of the melt during use. As can also be seen from the illustrations, the copper contact jaw 1 each has a single and thus central coolant inlet opening and coolant outlet opening 13, 14, which are fluidly connected to the plurality of cooling channels 15.

[0021] In the embodiment shown, the plurality of cooling channels 15 are formed from a plurality of individual cooling channel groups 16 to 30, each of which extends axially 16, 18, 20, 22, 24, 26, 28, 30 or radially 17, 19, 21, 23, 25, 27, 29 through the base body 4 and is thus arranged alternately with one another. Each of the cooling channel groups 16 to 30 consists in the present case of four individual cooling channels 15, each of these individual cooling channels 15 being formed by a separate deep hole drilled through a corresponding surface 5, 9, 11a, 11b, 12a, 12b in the base body 4. In other words, each of the cooling channels 15 is formed by a deep hole open on one side, which is subsequently closed by threaded plug screws (not shown).

[0022] A coolant, for example water, introduced via the central coolant inlet opening 13 therefore initially flows via the four individual channels 15 of the first group 16 in the direction of the second end face 10 (see arrow 31 in Figure 2 ). The coolant is then fed to the cooling channels 15 of the third group 18 via the four channels 15 of the second group 17 (see arrow 32 in Figure 2 ), through which it flows through the copper contact jaw 1 in the direction of the first end face 9 (see arrow 33 in Figure 2 ). The coolant then flows via the four channels 15 of the fourth group 19 to the channels 15 of the fifth group 20, via which it flows through the copper contact jaw 1 again in the direction of the second end face 10 (see arrows 34, 35 in Figure 4 ). As can be seen from the Figures 4 and 5As can also be seen, the coolant then flows via the four channels 15 of the sixth group 21, which are arranged centrally in the axial direction and run in the radial direction, into the cooling channels 15 of the seventh group 22, via which it flows through the copper contact jaw 1 in the direction of the second end face 9 (see arrow 36 in Figure 5 and arrow 37 in Figure 2 ). The coolant flows from the in the following four channels 15 of the eighth group 23 Figure 2 shown left copper contact jaw half into the radially opposite right copper contact jaw half (see arrow 38 in Figure 2 ), in which it flows through the individual groups 24 to 30 in the opposite direction to the left copper contact jaw half, as shown by the arrows 39 to 43 in the Figures 2 , 3 and 5 is shown.

[0023] In the present embodiment, the copper contact jaw 1 has an axial length of 750 mm, a width of 600 mm, and a thickness of 150 mm. The individual cooling channels 15 were created using a deep-hole drill with a diameter of 8.0 mm, allowing a minimum flow rate of 5000 L / h to be achieved across the entire cooling channel system.

[0024] As can be seen particularly from the illustrations in the two Figures 1a / 1b As can be seen, all deep-hole bores are spaced as far as possible from the second end face 10, which in use faces the melt, so that the threaded plug screws, by means of which the individual openings of the deep-hole bores are closed, are not directly exposed to the radiant heat of the melt. Reference symbol

[0025] 1Copper contact jaw 2Electrode support arm 3Fastening means 4Base body 5Rear surface 6Front surface 7Contact surface 8Contact surface 9First end surface 10Second end surface 11aSide surface 11bSide surface 12aSide surface 12bSide surface 13Coolant inlet opening 14Coolant outlet opening 15Cooling channels 16Axial cooling channel group 17Radial cooling channel group 18Axial cooling channel group 19Radial cooling channel group 20Axial cooling channel group 21Radial cooling channel group 22Axial cooling channel group 23Radial cooling channel group 24Axial cooling channel group 25Radial cooling channel group 26Axial cooling channel group 27Radial cooling channel group 28Axial cooling channel group 29Radial cooling channel group 30Axial cooling channel group 31Arrow 32Arrow 33Arrow 34Arrow 35Arrow 36Arrow 37Arrow 38Arrow 39Arrow 40Arrow 41Arrow 42Arrow 43Arrow

Claims

1. Copper contact jaw (1) for an electric smelting unit, preferably for use in an electric smelting unit, which jaw can be mounted on an electrode support arm (2) of the smelting unit and by way of which jaw an electrode of the smelting unit is electrically conductively connectible with the electrode support arm (2), comprising a base body (4) with a rear surface (5) and an oppositely arranged front surface (6), a first end surface (9) and a second, oppositely arranged end surface (10), as well as at least one first side surface and at least one second side surface (11a, 12a), two contact surfaces (7, 8) which are arranged on the front surface (6) of the base body (4) and are formed to be mirror-symmetrical with respect to one another and which extend axially along the base body (4), a cooling channel system with a coolant inlet opening (13) and a coolant outlet opening (14) as well as a plurality of cooling channels (15) which extend axially and radially through the base body (4), characterised in that the cooling system comprises at least ten individual cooling channels.

2. Copper contact jaw (1) according to claim 1, wherein each of the cooling channels (15) has a diameter in the range of 4.0 to 16.00 mm, preferably a diameter in the range of 5.0 to 14.00 mm, more preferably a diameter in the range of 6.0 to 12.00 mm.

3. Copper contact jaw (1) according to claim 1 or 2, wherein each of the cooling channels (15) is formed by a deep-hole bore open at one end.

4. Copper contact jaw (1) according to any one of the preceding claims, wherein the plurality of cooling channels (15) is formed from a number of cooling channel groups (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30), which each extend axially or radially through the base body (4) of the copper contact jaw (1).

5. Copper contact jaw (1) according to claim 4, wherein each of the plurality of cooling channel groups (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30) comprises at least two, preferably at least three, cooling channels (15).

6. Copper contact jaw (1) according to claim 4 or 5, wherein each of the cooling channels (15) of each cooling channel group (16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30) is formed by a deep-hole bore.

7. Copper contact jaw (1) according to any one of the preceding claims, wherein the coolant inlet opening (13) and a coolant outlet opening (14) are arranged in the rear surface (5) and at an end facing the first end surface (9).

8. Electric smelting unit, particularly an electric arc furnace, comprising an electrode support arm (2) as well as a copper contact jaw (1), which is arranged at the electrode arm (2), according to any one of the preceding claims.

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