JPS61245960A - Dripping type casting device - Google Patents

Abstract

PURPOSE:To obtain easily and quickly a billet and ingot consisting of prescribed comps. with a titled device which melts electrodes by the arc between a pair of the electrodes by providing a means for supplying an additive for component adjustment to the arc. CONSTITUTION:A pair of the electrodes 11 are installed to face each other horizontally apart at a spacing of an adequate length and electric current is supplied to the electrodes 11 by which the arc 12 is formed between the electrodes 11. The opposed ends of the electrodes 11 are melted by the arc 12 and fall in the form the liquid drops 13 into a casting mold 15. The liquid drops are solidified and the ingot 18 is obtd. The bar-shaped additive 14 contains the additive component for the purpose of forming the product having the prescribed compsn. by being added to the basic compsn. of the electrodes 11 and is continuously dropped and supplied by a suitable supplying device in the region right above the arc 12. The bottom end of the additive 14 is melted by the heat of the arc 12 and falls in the form of the liquid drops 13 like the opposed ends of the electrodes 11. The concn. of the easily evaporatable component is thereby adjusted to the prescribed value with high accuracy and the ingot consisting of the prescribed compsn. is easily and quickly obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a dropping casting apparatus capable of producing slabs and ingots having a fine crystal structure.

[Conventional technology]

Generally, slabs or ingots, which are intermediate materials for metal products, are manufactured by pouring molten metal into a continuous casting mold or an ingot mold and solidifying it.

However, in this technique, completely molten metal is cast into a mold, so the produced slab or ingot has a relatively large crystal grain size in its solidified structure. For this reason, when applying a reduction to the slab etc. in order to ensure mechanical properties, if a large reduction is applied, cracks will occur in the slab etc. Therefore, it is necessary to apply the reduction blade in multiple steps, but this requires a long processing time and also requires a large amount of thermal energy, resulting in high processing costs. The sensitivity to cracking due to the coarsening of the crystal grain size of the solidified structure is particularly remarkable in N1-based super heat-resistant alloys, and the manufacturing process becomes extremely complicated when manufacturing this type of alloy.

In order to eliminate these shortcomings in general casting technology, VADER (Vacuum Arc Doubt) has recently been developed.
A casting technology called 1@Electrode Remelting (vacuum arc two-electrode melting) method has been proposed (Japanese Unexamined Patent Publication No. 165271/1982).
In this method, as shown in Figure 4, an arc of 2
is formed and the opposing ends of electrode 1 are melted. The droplets 4 of the molten metal fall into the mold 3, are cooled by the mold 3, and solidify to produce an ingot 5.

In this case, the molten metal droplet 4 is slightly cooled in the process of falling from the electrode 1 into the mold 3, and becomes a semi-molten state. Therefore, the semi-molten metal 6 in the mold 3 solidifies in a state where the solid-liquid coexisting phase exists uniformly, so that the crystal grain size of the solidified structure of the ingot 5 is small. Therefore, even if a large reduction is applied, cracks will not occur in the ingot.

[Problem that the invention seeks to solve]

However, in conventional drip casting equipment, it is necessary to manufacture electrodes with the same composition as the ingot to be manufactured in advance, and preparing such electrodes for various steel types takes a lot of time and effort. This is a loss of thermal energy, which increases costs. Further, during the melting of the electrode, the evaporation of the component contained in the electrode (the component may evaporate, and the concentration of the component in the manufactured ingot may fall below a predetermined value).

[Failure to solve the problem]

This invention was made in view of such circumstances, and
It is possible to easily and quickly produce slabs and ingots having a fine crystal structure and a predetermined composition, and
It is an object of the present invention to provide a dropping casting device that can adjust the concentration of components that easily evaporate to a predetermined value with high precision.

The drip casting device according to the present invention includes a mold, a pair of electrodes, an arc forming means for forming an arc between the electrodes to melt the electrodes and causing the droplets to fall into the mold, and a component adjusting device for the arc. and an additive supply means for continuously supplying the additive and melting it by arc heat.

〔Example〕

Embodiments of the present invention will be specifically described below with reference to the accompanying drawings. FIG. 1 shows a dropping casting apparatus according to an embodiment of the present invention. A pair of electrodes 11 made of a metal whose composition includes the basic components of the ingot to be manufactured are installed horizontally facing each other at an appropriate length interval. This electrode 1
1 is supplied with current, and an arc 12 is formed between the electrodes 11. This arc 12 causes the opposing end of the electrode 110 to melt and drop as a droplet 13.

The rod-shaped additive 14 contains additive components to be added to the basic composition of the electrode 1 to obtain a predetermined product composition. (not shown) so that it is continuously supplied downward. The lower end of the continuously falling additive material 14 is melted by the heat of the arc 12, and falls as a droplet 13 in the same way as the opposite end of the electrode 11.

The droplets 13 produced by melting the electrode 11 and the additive material 14 fall into the mold 15. The mold 15 has a cylindrical shape with a bottom when producing an ingot with a circular cross section, or a rectangular cylindrical shape with a garden when producing an ingot with a rectangular cross section. It is made of refractory materials such as Note that it is also possible to configure the mold 15 with a water-cooled copper casting wall.

A coil 16 with a vertical winding axis is installed so as to surround the mold 15, and this coil J6 is supported by appropriate support means so as to be movable up and down. coil 22
1 is connected to a high frequency power source (not shown) that supplies a high frequency current with a frequency of, for example, 200 kHz.

In the drop casting apparatus configured as described above, first, when electricity is applied between the electrodes 11 to form an arc 12, the opposite end of the electrode J1 melts and droplets 13 of molten metal fall. When the additive 14 is lowered at an appropriate speed at the same time as the arc 12 is formed, the lower end of the additive 14 is melted by the heat of the arc 12 and falls as a droplet 13. This droplet 1
3 is air-cooled before falling from the arc 12 into the mold 15, and is cast into the mold 15 in a semi-molten state. This semi-molten metal 17 is cooled and solidified by the mold 15 in a state in which a solid-liquid coexisting phase exists uniformly in the casting history 5. Therefore, the crystal grain size of the solidified structure of the obtained ingot 18 is small.

In this case, the power applied to the electrode 11 may be adjusted to
Adjust the melting rate of additive 14 and the cross-sectional area of electrode 1
By adjusting the feed rate of lowering mold 1
The composition of the ingot can be adjusted to a predetermined product composition by appropriately mixing the amount of the electrode 11 cast into the ingot 5 and the amount of the additive 14.

If the temperature of the semi-molten metal 17 in the mold 15 is too low, uniform alloying may become difficult. In this case,
A high frequency current is supplied to the coil 16, and the coil 16 is moved upward to match the position of the meniscus of the semi-molten metal 17. As a result, the semi-molten metal 17 in the mold 5
The meniscus portion of the electrode 11 is heated by high frequency induction.
Alloying with the basic composition and the additional components of the additive 14 is easy, and a homogeneous ingot without segregation can be obtained.

FIG. 2 is a schematic diagram of the electrode surroundings of a dropping casting apparatus according to a second embodiment of the present invention. The additive 14 is disposed so as to fall continuously between a pair of horizontally opposed electrodes 11, and a DC power supply 19 is connected between each electrode 11 and the additive 14 with the electrode 1 at a positive potential. is connected. In this embodiment, a DC power supply 1 is provided between each electrode 11 and the additive 14.
9 is formed, each electrode 11 and additive 1
The end opposite to 4 is melted by arc 20. The electrode 11 and additive 14 thus melted become droplets 13 and are cast into a mold 15 as in the first embodiment (see FIG. 1).

Next, a third embodiment of the present invention will be described based on FIG. A hopper 21 is installed above the electrode 11 having a basic composition, and in this hopper 421 is added powder or lumps containing additional ingredients to be added to the basic composition to make a predetermined product composition. agent 22 is stored.

This additive 22 is cut out in a predetermined amount from the hopper f2 and dropped into the arc 12 formation area between the electrodes 11 by an appropriate guide means 23.

In the drip casting device configured in this way,
An arc 12 is formed between the electrodes 11, and at the same time as the arc 12 is formed, the additive 22 is supplied from the hopper 421 to the arc 12.
drop into the area.

As a result, the additive 22 is melted by the heat of the arc 12, becomes a droplet 13 together with the molten droplet of the electrode 11, and forms a droplet 15 in the mold 15.
fall inside. This droplet 13 is cooled by a mold 15 to produce an ingot 18, as in the first embodiment.

In each of these embodiments, the electrode 11 uses a metal with a basic composition containing basic components applicable to various steel types, and additives 14.22 are added to the electrode with this basic composition to form an ingot. Metals containing additives are used to make the steel into a predetermined composition of various steel types. However, when producing ingots containing components that are particularly prone to evaporation, additive 1
A metal containing this easily evaporable component may be used as 4.22, and the evaporation loss may be compensated for by melting the additive 14.22.

Although each of the embodiments described above relates to an ingot type casting apparatus, it is also possible to apply the present invention to a continuous casting type casting apparatus that continuously draws slabs. In this case, there is no need to move the high-frequency heating coil 16 upward, and it is sufficient to provide it at a fixed meniscus position.

Yet again. Although this embodiment relates to a drop casting apparatus using the VADER method, it goes without saying that the present invention is not limited to the VADER method and can be applied to other drop casting techniques.

〔Effect of the invention〕

According to this invention, for various steel types, by simply preparing electrodes made of metals with basic compositions and adjusting the type and supply amount of additives, slabs and slabs with desired product compositions can be produced.
Since an ingot can be obtained, it is not necessary to prepare electrodes having various compositions depending on the steel type, and slabs and ingots having fine crystal grains can be easily and quickly produced.

Furthermore, steel types that have components that easily evaporate can be manufactured by using additives containing these components to replenish the evaporation loss of such components.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing a dropping casting apparatus according to a first embodiment of the present invention, FIG. 2 is a schematic diagram showing a dropping casting apparatus according to a second embodiment of the invention, and FIG. 3 is a schematic diagram showing a dropping casting apparatus according to a second embodiment of the invention. Third part of this invention
FIG. 4 is a schematic diagram showing a dropping casting device according to the embodiment, and FIG. 4 is a schematic diagram showing a conventional dropping casting device. 11... Electrode, 12... Arc, 13... Droplet,
14.22...Additive, 15...Mold, 17...
Semi-molten metal, 18... ingot.

Claims (1)

[Claims] A mold, a pair of electrodes, an arc forming means for forming an arc between the electrodes to melt the electrodes and causing the droplets to fall into the mold, and continuously supplying additives for composition adjustment to the arc. 1. A dropping casting device, comprising: additive supply means for melting by arc heat.