JPH0159340B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention involves melting metal scraps, particularly scraps of refractory metals such as titanium, zirconium, or their alloys, with an electron beam or plasma electron beam in a vacuum melting furnace, or by melting metal scraps using a consumable electrode. The present invention relates to a method of manufacturing an ingot by melting an electrode made from the metal scrap as a consumable electrode in a type arc melting furnace. [Prior Art] Conventionally, metal scraps, particularly scraps of refractory metals such as titanium, zirconium, or alloys thereof, are melted to produce ingots.
Chips or small lumps of scrap fed into the hearth of a vacuum melting furnace are melted by an electron beam or plasma electron beam, and the molten metal collected in the hearth is transferred to a water-cooled mold and solidified into cast metal. Either the lump is pulled out from below the mold, or by the consumable electrode arc melting method, the consumable electrode made from the metal scrap is suspended in a water-cooled copper crucible, and a direct current arc is applied between the tip and the molten metal in the copper crucible. As a result, the electrode itself was gradually melted from its tip and dropped into a copper crucible to form a molten metal pool, and the molten metal pool was solidified from below to produce ingots. However, in the former method of manufacturing ingots, which uses electron beams or plasma electron beams in a vacuum melting furnace, it is necessary to sort the scraps in advance according to their size. Since only scrap can be processed, the work is time-consuming and the range of scrap that can be processed is limited.The present inventors first investigated the problem of heavy impurities in metal scrap, such as tungsten carbide-based carbide. As an ingot manufacturing method that can be advantageously applied when tool chipping fragments are present, the metal scrap is packed into a bottomed tube made of the same material as the metal scrap, and the tube is hearthed in a vacuum melting furnace. While held horizontally above, the tube material is melted by heating it with an electron beam or plasma electron beam sequentially from the bottom end to the other end, and the molten metal thus generated is allowed to fall into the hearth. After collecting the molten metal in the hearth, the supernatant of the molten metal is injected into a water-cooled mold by overflow and solidified.
60-120158), and metal scrap produced by heating with the electron beam or plasma electron beam as an ingot manufacturing method that can also reduce power consumption if heavy impurities are not mixed in the metal scrap. We have proposed a method (Japanese Patent Application No. 120157/1986) in which molten metal from scrap is directly dropped into a water-cooled mold and solidified in the water-cooled mold. In the manufacturing method of ingots that are melted into electrodes, scraps are first sorted by size, and then larger items are welded together in the atmosphere using an argon seal to make electrodes. The lumps are optionally pressed with titanium sponge to make briquettes, which are welded together to make electrodes, and the medium-sized lumps between the above two are crushed into fine particles. After that, briquettes are made by pressing with titanium sponge at will, and then welded together to make electrodes, so there is a problem that it takes a lot of time and effort to make consumable electrodes. The present inventors first placed bottomed tubes made of the same material as the metal scraps filled with the metal scraps in a consumable electrode type arc melting furnace, with their bottoms facing each other, and placed them on a water-cooled mold. A method of melting the metal scrap by generating an arc between the tubes packed with the metal scrap while holding the metal scrap horizontally, and causing the molten metal thus generated to fall into a water-cooled mold and solidify (particularly 1986-120159). [Problems to be Solved by the Invention] All of the above ingot manufacturing methods use a tube with a bottom for stuffing metal scraps, and when stuffing scraps into such a tube, the scraps must be placed on one side. Since it can only be supplied through a narrow opening, the filling process is troublesome, and since the pipe is open at only one end, it is difficult to visually check the filling state of the metal scrap packed inside the pipe. Moreover, depending on the size and shape of the scrap, large voids can easily form inside the pipe, so the overall filling rate is
Not only is it low (about 50 to 60%), but it is also impossible to pack the scrap uniformly, so when melting with an electron beam or plasma electron beam in a vacuum melting furnace, the amount of heat that must be supplied to each part of the pipe during melting changes, making it difficult to adjust the melting rate to a constant value, and in the case of consumable electrode type arc melting, it is difficult to stably obtain a uniform arc. [Findings based on research] Therefore, the inventors of the present invention have conducted various studies in order to solve such problems. (1) Instead of the bottomed tubular member for filling the metal scrap, the present inventors have found that: If a top-opening box material is formed by cutting a tube material with a polygonal cross section in the axial direction, this box material allows scraps to be stuffed from above, making the stuffing process easier. Furthermore, not only can the filling condition of the entire inside of the box material be determined visually, but also scraps can be supplied from above throughout the entire box material, making it extremely easy to evenly distribute scraps inside the box material. (2) The material of the box material is If the material is not the same as that of the metal scrap, the box material melted together with the scrap and mixed into the ingot will change its composition, but if the variation is within an allowable range, the material of the box material will be the same as that of the metal scrap. It has been found that even if the material of the box material is not the same as that of the metal scrap, it is sufficient if the material of the box material contains one or more of the same components as those of the metal scrap. [Means for Solving the Problems] This invention was invented based on the above knowledge, and it provides a method for producing ingots by melting metal scrap in a vacuum melting furnace or a consumable electrode type arc melting furnace. With the aim of performing melting operations easily, stably, and efficiently, metal scrap is melted in a vacuum melting furnace or consumable electrode type arc melting furnace, and the resulting molten metal is solidified in a water-cooled mold. In the method for producing an ingot from the metal scrap, the ingot contains one or more of the same components as the metal scrap,
A top-opening box material having a shape formed by cutting a tube material with a polygonal cross section in the axial direction, and having partition members at both ends or one end, or having no partition members at both ends. The metal scrap packed in the metal scrap is heated by an electron beam or a plasma electron beam from one end to the other while being held horizontally in the vacuum melting furnace, or in the consumable electrode type arc melting furnace. Combine an even number of metal scraps, hold them horizontally with their ends facing each other, and generate an arc between these ends to melt the metal scrap together with the box material, and the resulting molten metal. The molten metal is solidified by directly dropping it into a water-cooled mold, or by once storing the molten metal in a hearth and then dropping its supernatant liquid into the water-cooled mold by overflow.
The present invention provides a method for manufacturing the ingot. [Specific structure and operation of the invention] Hereinafter, the specific structure and operation of the present invention will be explained. 1. Box material The box material filled with scraps melts together with the scraps and mixes into the ingot, which affects the material of the ingot, so it is most preferable that the material of the box material be the same as the scrap material. Usually, scraps with slightly different materials are mixed and processed, and there is a certain tolerance range for the composition of the ingot that becomes the product. The fluctuation of
The material of the box material does not necessarily have to be the same as the material of the scrap, as long as the composition does not fall outside the range of composition required for the ingot, and variations in the composition of the ingot due to such mixing may affect the composition of the ingot. Within this range, it is sufficient to make the material of the box material contain one or more of the same components as those of the metal scrap. The box material used in this invention may have any shape in cross section, that is, it may have any shape as long as the cross section is a polygon with some sides missing. Usually, a box material 1 with a U-shaped cross section as shown in Fig. 4 is used because it is easy to manufacture and handle.
is conveniently used. For example, the plate-shaped partition members 1a, 1a shown in FIG. This is to prevent scrap from falling out of the box material until it is supplied to the container and melted.
This partition member may be of any type as long as it prevents such spillage.For example, if the size of the scrap is large to a certain extent, it may be made of a net shape, a lattice shape, or a slit shape. If there is no risk of scraps spilling out, this partition member may be provided only at one end of the box material, or its attachment may be omitted altogether. Although this box material can be manufactured by any method, it is generally advantageous to manufacture it by welding and assembling plates obtained by descaling after hot rolling. In manufacturing, it not only allows the use of narrower plates than circular pipes, but also has the advantage of not requiring hot rolling or heat treatment, which must be carried out under strict temperature control. (2) Casting method In this invention, which manufactures ingots from metal scraps, various types of castings are applied to the box material 1 having the partition member 1a, as shown in side views in FIGS. (i) In the vacuum melting furnace, hold the scraps horizontally on the water-cooled mold 3 (Fig. 1) or the hearth 4 (Fig. 2), and heat the scraps S without sorting. When the metal scrap S is gradually introduced from one end into the zone 5 heated to a high temperature by the electron beam or plasma electron beam 2,
After melting together with the box material 1 into the water-cooled mold 3, as shown in FIG. 1, or melting down into the hearth 4, as shown in FIG. 2, to form a pool of molten metal 6, The supernatant of this molten metal 6 overflows from the hearth 4 into the water-cooled mold 3 and forms a pool of molten metal 6 above the water-cooled mold 3, while the molten metal 6 is cooled and solidified by the water-cooled mold 3 below. Ingot 7
(ii) a box material 1 packed with the scrap S;
are arranged horizontally on a water-cooled mold 3 with their ends facing each other, as shown in FIG. 3, and when an arc 8 is generated between them as consumable electrodes, both electrodes are formed. The metal scrap S melts down into the water-cooled mold 3 together with the box material 1, forming a pool of molten metal 6 above the water-cooled mold 3, while below it the molten metal 6 is cooled and solidified by the water-cooled mold 3. An ingot 7 is formed. In addition, in this method, as described in the above (i), after the molten metal 6 is once collected in the hearth 4, the supernatant may be allowed to fall into the water-cooled mold 3 by overflow, and such a hearth can be used. The method used is advantageously used to remove heavy impurities such as tungsten carbide contained in scrap, while the previously described method without hearth is
If there is no risk of such impurities being mixed into the scrap, it is advantageously used as a method of reducing power consumption. In this invention, the box material may be arranged in any manner as long as the melted raw material does not slip or roll down from the box material during the melting operation. As used herein, the term "horizontal" refers not only to completely horizontal, but also to a substantially horizontal, sideways position, which naturally includes the above meaning. After the partition member 1a that prevents the scraps from falling out melts down, some of the scraps packed in the box material remain undissolved during the melting process and are placed in the water-cooled mold 3 or the hearth. Scraps may fall into the molten metal pool formed in step 4, but because of their relatively small size, such scraps easily fall into the molten metal pool heated by the electron beam or plasma electron beam or arc. dissolve in In this invention, the number of box materials to be processed at a time is not necessarily one or one pair. For example, in order to increase productivity, a plurality of box materials may be fed into the heating zone 5 at the same time, or two or more pairs of box materials may be processed at a time. The consumable electrodes may be placed opposite each other to generate an arc 8 between them. The present invention is particularly advantageously applied to the production of ingots from scraps of refractory metals such as titanium, zirconium, or their alloys, but it can also be applied to scraps of other metals by heating with an electron beam or plasma electron beam. It goes without saying that the present invention can be applied to any metal scrap suitable for melting by vacuum melting or consumable electrode arc melting. [Examples and effects based on the examples] Next, the present invention will be explained with reference to examples. It has a shape as shown in Fig. 4, and has a width:
350mm x height: 600mm x length: 2400mm x board thickness: 3mm
A pure titanium box material with a partition member having dimensions of
Minimum: 5 mm square to maximum: -4% V composition:
Packed with titanium alloy scraps of various dimensions up to approximately 150mm x 150mm x 400mm (weight 35Kg). The total weight of the scrap at this time was 1,600 kg, and the filling rate reached 74%. This was placed horizontally in a plasma beam melting furnace as shown in Figure 1, under vacuum (0.01 mmHg), and the plasma output:
Diameter: 440mm x irradiated with plasma electron beam under conditions of 500KW, box material advancement speed: 2cm/min
A cylindrical ingot with dimensions of length: 2100 mm and weight of approximately 1.4 tons was produced. In this melting operation, the ingots were packed uniformly into the box material at a high filling rate as described above, so the melting rate could be easily adjusted to a constant level, and therefore the melting operation could be controlled. This made it easier to use, shortened work time, and reduced power consumption. The component analysis values of the scrap used in this example and the obtained ingot were as shown in Table 1.

[Comprehensive effect of the invention]

As is clear from the above explanation, according to the present invention, it becomes extremely easy to pack scraps into the box material that is the scrap holding member, and the scraps can be uniformly filled into the box material. In the vacuum melting method using an electron beam or plasma electron beam, the melting rate can be easily adjusted to a constant value, and in the consumable electrode type arc melting method, a uniform arc can be stably obtained. The melting operation can be easily controlled, and scraps can be packed into the box material at a high filling rate, so industrially useful effects such as increased melting efficiency and workability can be obtained.

[Brief explanation of drawings]

Figures 1 to 3 are explanatory diagrams drawn from the side to show the main points of this invention, and Figures 1 and 2 show a vacuum melting method using an electron beam or plasma electron beam as a heating source. , FIG. 3 shows a consumable electrode type arc melting method, and FIG. 4 is a perspective view showing an example of a box material used in the present invention. In the figure: 1... Box material, 2... Plasma beam, 3... Water-cooled mold, 4... Hearth, 5... Heating zone, 6... Molten metal, 7
...Ingot, 8...Arc, S...Scrap.

Claims (1)

[Scope of Claims] 1. A method for manufacturing an ingot from metal scrap by melting the metal scrap in a vacuum melting furnace and solidifying the resulting molten metal in a water-cooled mold to form an ingot, comprising: It has a shape formed by cutting in the axial direction a tube material that contains one or more of the same components as the constituent components of the metal scrap and has a polygonal cross section, and has a partition member at both ends or one end, Alternatively, a top-opening box material with no partition members at either end filled with metal scraps is held horizontally in the vacuum melting furnace, and an electron beam or plasma electron beam is applied from one end to the other. By heating with a beam, the metal scrap is melted together with the box material, and the resulting molten metal is dropped directly into a water-cooled mold, or the molten metal is temporarily stored in a hearth and the supernatant is allowed to overflow. A method for manufacturing the ingot, characterized in that the molten metal is solidified by dropping it into a water-cooled mold. 2. A method for manufacturing an ingot from the metal scrap by melting the metal scrap in a consumable electrode type arc melting furnace and solidifying the molten metal thereby produced in a water-cooled mold to form an ingot. It has a shape formed by cutting a tube material having a polygonal cross section in the axial direction, and has a partition member on both ends or one end, or In the consumable electrode arc melting furnace, an even number of the metal scraps packed in a top-opening box material without any partition members are assembled, and their ends are held horizontally with their ends facing each other; An arc is generated between these ends to melt the metal scrap together with the box material, and the resulting molten metal is dropped directly into a water-cooled mold, or after this molten metal is once stored in a hearth. , characterized in that the supernatant is allowed to fall into a water-cooled mold by overflow, and the molten metal is solidified.
A method for producing the ingot.