RU2331679C2 - Method of production of consumable electrode - Google Patents

Abstract

FIELD: metallurgy.

SUBSTANCE: invention refers to special electrometallurgy, particularly to fabricating of pressed consumable electrodes made out of high reactive metals and alloys, for example of titanium ones, with further remelting. According to this method reinforcing bars are installed into a hollow container, then, in batches, loose charge is loaded into the container and jointly pressed with a compression-ram. As reinforcing bars, long-length wastes of remelted metal are used, which are fixed in the electrode at pressing of the first and the last batch of charge, while at pressing the intermediary batches of charge the reinforcing bars are continuously fed into a gap between the container and the compression-ram and they are pressed into the surface layer of the electrode with formation of continuous reinforcing bars along the length; the reinforcing bars are made as a package composed out of thin sheet long length wastes. As pressing goes the reinforcing bars are pressed into the electrode by spiral, and the start angle of different bars is set either the same or different. This invention reduces labour input at production of consumable electrodes, increases their mechanical strength, facilitates including of long length wastes into the electrode composition omitting their preliminary processing.

EFFECT: reduction of labour input at production of consumable electrodes and increase of their mechanical strength.

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Description

The invention relates to the field of special electrometallurgy, namely to the manufacture of extruded consumable electrodes, mainly from titanium and its alloys, for subsequent remelting.

There is a method of producing a consumable electrode for vacuum arc remelting (VDP) by pressing portions of lump and bulk charge materials through a cone feed matrix (see Titanium alloys. Melting and casting of titanium alloys. Edited by V.I.Dobatkin. M.: Metallurgy ", 1978, p. 265-271).

This method is quite productive and allows you to involve in the composition of the electrode various types of return charge waste after their appropriate processing.

The disadvantage of this method is the weak mechanical connection between the components of the charge, which with an increase in the size of the electrode leads to a decrease in its strength, destruction during transportation and during remelting, creates emergency situations in vacuum arc furnaces, and causes the marriage of ingots and electrodes, thereby reducing the yield of metal.

Closest to the technical nature of the claimed invention is a method of producing a consumable electrode for a VDP, including the manufacture of charge components of a given size, and part of the charge is made in the form of reinforcing bars of limited length, portioned loading of reinforcing bars and bulk and bulk components of the charge into the container and the subsequent joint pressing with periodic fixation of the rods (RU 2264887, C22B 9/20, 11.27.2005) - prototype.

This method allows you to slightly increase the strength of the electrode and increase the proportion of returnable waste in it.

The disadvantage of this method is the complexity of the implementation and the great complexity.

The reinforcing bars used must have well-defined geometric dimensions, in particular length and thickness. The length of the reinforcing bars is set not less than the total length of the pressing perimeters and the upper conical part of the container (and when pressing the last portion of the charge, not exceeding the pressing dimensions) and not more than the total length of the perimeters of the entire electrode and the upper conical part of the container. Otherwise, either underutilization of the entire length of the rods or their shortage is possible. Periodic fixation of the rods leads to the fact that the rods with a thickness of less than 3 mm during the reverse stroke of the stamp are torn and practically when pressed on presses with a force of 2500-10000 tf, the rods should be at least 8-10 mm thick.

Special manufacture of such rods is associated with significant labor costs. In addition, the installation of the rods before each loading, their periodic fixation and the need to give them a certain configuration by idling the press stamp leads to a decrease in the productivity of the electrode pressing process.

The high complexity of the method is not justified by an increase in the strength of the electrode, since in such places at the places of passage (along the end surface of the blocks) of the bottom of the molded rods, the adhesion forces between the blocks are weakened, which leads to the fall of unmelted pieces of the charge into the molten metal bath during the melting of the electrode.

The combination of these disadvantages limits the possibility of industrial application of the known method.

The problem to which this invention is directed is to reduce the complexity of manufacturing a pressed electrode and increase its strength due to the use of long production waste as reinforcing bars.

The problem is solved in that in the method for producing a consumable electrode for subsequent remelting, comprising installing reinforcing rods from the waste of remelted metal in a hollow container, portioning the bulk charge into the container and pressing them together with a press stamp, according to the invention, lengthy waste is used as reinforcing rods which are fixed in the electrode when pressing the first and last portion of the mixture, and when pressing intermediate portions of the mixture, the reinforcing bars are continuously ayut into the gap between the container and the press stamp and is pressed into the surface of the electrode layer to form a continuous electrode along the length of reinforcing bar, wherein the reinforcing bars operate as a package assembled from thin sheet wastes.

In addition, the reinforcing bars are pressed into the electrode in a spiral as they are pressed, and the helix of different rods is set equal or different.

When pressing intermediate blocks of the electrode, long reinforcing bars are pressed into the electrode mainly in its surface layer, providing high-quality adhesion of the charge components along the end surfaces of the blocks and additionally strengthening the peripheral connection of the blocks.

Since the rods are not fixed in this case, the possibility of their rupture during the course of the press stamp is excluded. This allows you to use as reinforcing rods packages collected their thin-sheet (from 0.1 to 3.0 mm thick) production waste without their preliminary relationship with each other. The sliding of the inner layers of the packet relative to the outer ones in the pressing direction, which occurs during the forward stroke of the stamp, causes the adhesion of the individual layers of the packet in this section. Due to this, the possible destruction of one or more inner layers of the package during the reverse stroke of the stamp does not violate the overall integrity of the reinforcing multilayer rod.

The essence of the proposed method is illustrated by drawings.

Figure 1 shows a General view of the container before pressing the next portion of the mixture with the reinforcing bar in the form of a bag, recruited from long-sheet thin waste; figure 2 shows the container during pressing the mixture of reinforcing bars with a press fitting in a spiral, α is the angle of approach of the spiral.

Example 1 (FIG. 1)

A consumable electrode was made for a VDP with a diameter of 220 mm, a length of 1,500 mm by pressing on a horizontal hydraulic press with a force of 5 thousand tonnes, using a reinforcing bag with a length of 3400 mm, a width of 50 mm, a thickness of 10 mm and a thickness of individual strip bands of 0.1-3.0 mm

Through a loading funnel 1 into the conical cavity 2 of the container 3, bounded by the upper flat end of the previously pressed electrode 4, lay a multi-layer reinforcing bar 5, made in the form of a package, recruited from long-length sheet-metal wastes of sheet-rolled production.

After the rod 5 is deformed, the first portion 6 of the charge is poured into the container and pressed with a stamp with a figured washer 7. In this case, the reinforcing bar is fixed in the first block 8 of the electrode 9. Two diametrically opposite sections of the reinforcing bar protrude into the cavity of the container, creating an additional rigid connection of the pressed block with the next portion portion.

After removing the stamp from the cavity of the container, the next portion of the charge is poured into it and it is pressed together with the reinforcing bar. In this case, the rod is in a free, unfixed state. In the direct course of the press stamp and compression of the reinforcing bar, the thin strips forming it slide relative to each other in the pressing direction, which helps to maintain the overall integrity of the bar. The pressing process is continued until a consumable electrode of the required length is obtained. The ends of the reinforcing bar are fixed in the last portion of the electrode during pressing by a stamp with a flat washer 10.

Example 2 (figure 2)

A consumable electrode was made for a VDP with a diameter of 490 mm and a length of 5500 mm by pressing on a vertical hydraulic press with a force of 10 thousand tf using reinforcing bars with dimensions of 8 × 60 × 7500 mm.

In the conical cavity of the container 3, bounded by the upper flat end of the previously pressed electrode (not shown), three reinforcing rods 5 are set in the form of a strip at a spiral angle α = 15 °.

After installing the rods in the container 3, a portion of a pre-mixed lump and bulk mixture 6 of a predetermined fractional and chemical composition is poured. The filled charge 6 together with the rods 5 is pressed with a stamp with a figured washer 7, fixing the rods in the first block of the electrode.

Next, filling the portion of the mixture and its joint pressing with long reinforcing bars is carried out analogously to example 1.

Changing the angle of inclination of the reinforcing bar relative to the axis of the electrode as it is pressed, the pitch of the spiral is regulated, ensuring the optimal content of sheet trim in the total volume of the charge.

The advantages of the proposed method for producing consumable electrodes in comparison with the prototype are as follows:

- Reduces the complexity by eliminating the preliminary processing of waste and eliminating a number of operations from the direct process of pressing the electrode.

- Increases the mechanical strength of the electrode due to the elimination of areas of weak adhesion of the blocks (on the end surfaces).

- It provides the possibility of non-waste involvement in the composition of the electrode of lengthy production wastes without their preliminary processing.

- Expanding the technological capabilities of the method by varying the type and method of pressing in reinforcing bars.

- The cost of manufacturing 1 ton of consumable electrode is reduced.

Claims (3)

1. A method of producing a consumable electrode for subsequent remelting, comprising installing reinforcing rods in a hollow container, portioning the bulk charge into the container and pressing them together with a press stamp, characterized in that lengthy remelted metal wastes are used as reinforcing rods, which are fixed in the electrode when pressing the first and last batches of the charge, and when pressing the intermediate batches of the mixture, the reinforcing bars are continuously fed into the gap between the container and the stamp they are pressed into the surface layer of the electrode with the formation of continuous reinforcing bars along the length of the electrode. 2. The method according to claim 1, characterized in that the use of reinforcing bars in the form of a package recruited from long-sheet thin waste. 3. The method according to claim 1 or 2, characterized in that the reinforcing bars are pressed into the electrode in a spiral as they are pressed, and the angle of approach of the spiral of different reinforcing bars is set the same or different.

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