JPS5811296B2 - Non-contaminating casting methods and equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a casting method and apparatus for encapsulating the pouring metal flow with non-oxidizing gas in the casting process of steel ingots, billets, and castings to prevent atmospheric pollution of the molten metal. .

Conventionally, as a method for preventing atmospheric pollution of molten steel in the casting process, as shown in FIG. The pouring stream 9 is encapsulated with non-oxidizing gas and cast.

However, in these methods, the ejected non-oxidizing gas spreads widely, so in order to create a preferable non-oxidizing atmosphere (for example, less than 0.8 parts oxygen in the atmosphere) near the pouring flow 9, a large amount of non-oxidizing gas is required. It is economically disadvantageous because sexual gas must be blown out.

In addition, in order to create a non-oxidizing atmosphere in the space (injection pipe, runner, mold) through which the pouring stream 9 should pass, a non-oxidizing gas is applied to the space through which the pouring stream 9 should pass for a relatively long period of time before pouring. It is necessary to keep gushing water continuously, and the waiting time before pouring becomes long.
The heat loss of the molten metal in the ladle is large.

Furthermore, the structure of the bottom groove of the ladle 10 is complicated, and the ladle 10 and the injection pipe 1 must be placed as close as possible in order not to reduce the non-contamination effect, which is very bad from the viewpoint of casting workability.

As a result of various studies in view of the above-mentioned circumstances, the inventors of the present application have found that when casting in the atmosphere, oxidation of the molten metal occurs near the molten metal surface in the injection pipe, where the flow of the molten metal entrains oxidizing gases such as the atmosphere, and violently stirs just below the molten metal surface. The inventors have discovered that the gas-liquid reaction is accelerated by the reaction of gas and liquid, leading to the present invention.

That is, the gist of the present invention is as follows: (1) Using an injection pipe equipped with a toric body having a gas outlet between the injection pipe funnel and the injection pipe brick, a non-oxidizing gas is introduced from the gas outlet into the interior of the injection pipe brick. A non-contaminating casting method characterized by injecting oxidizing gas and pouring the metal in a non-oxidizing gas atmosphere.

(2) A non-contaminating casting device characterized by comprising a torus having a gas outlet between the injection pipe funnel and the injection pipe brick, and a conduit for introducing non-oxidizing gas into the torus.

(3) The non-contaminating casting apparatus according to claim 2, wherein the gas outlet is a torus made of a porous refractory material.

(4) The non-contaminating casting apparatus according to claim 2, which is a toric body having a single ejection port.

(5) The non-contaminating casting apparatus according to claim 2, characterized in that it is a toric body having a plurality of ejection ports.

The object of the present invention is to provide an effective non-oxidizing casting method and apparatus that has extremely good casting workability and enables a reduction in the amount of non-oxidizing gas emitted.

The toric body having a spout according to the present invention is not limited to an integral body, but also includes a toric body having a toroidal shape formed by incorporating divided bodies.

Moreover, any shape of the jet nozzle may be used without any problem in the present invention.

Next, the present invention will be explained in detail with reference to the drawings.

FIG. 2 is a schematic diagram showing one embodiment of the non-contaminating casting apparatus of the present invention, in which a gas conduit 7 is arranged on top of the injection pipe bricks 2 stacked from below in the same way as in ordinary atmospheric casting. A torus 5 with an outlet 6 is loaded.

Then, the injection pipe funnel 3 is left standing to complete the assembly.

Before pouring the molten metal into the mold, in order to create a non-oxidizing atmosphere in the space through which the molten metal passes, non-oxidizing gas (
For example, Ar gas, etc.) is ejected.

Since the timing of the start of gas ejection can be selected independently of the operation of the ladle, when the ladle for pouring molten metal is transported above the pouring pipe 1, the molten metal passes through the pouring pipe so that pouring is possible immediately. The space is already in a favorable non-oxidizing atmosphere, there is no need to wait for the ladle before pouring, and furthermore, the non-oxidizing gas is ejected directly into the injection pipe brick 2, so there is less wasteful diffusion of gas. , the gas replacement effect is good with a small flow rate of gas, and the non-contamination effect is also good.

In particular, in the apparatus shown in FIG. 2, which is an embodiment of the apparatus of the present invention, the gas flow ejected horizontally from the ejection port 6 flows into the injection pipe 1.
They collide with each other near the central axis of the bricks and blow out upwards, and the air is not drawn into the injection tube brick 2, resulting in an even better replacement effect.

Normally, at an argon gas flow rate of 20 ONl/min, a preferable non-oxidizing atmosphere in which the oxygen content in the injection tube 1 is less than 0, s% can be obtained within 20 seconds.

Next, the features of the present invention will be explained in more detail with reference to examples.

Example 1 Molten steel of SCM21 produced in an arc furnace was poured by the normal atmospheric casting method and the method shown in FIG. 2, which is an embodiment of the present invention method, and the molten steel and steel ingot were Figure 5 shows the results of examining the changes in nitrogen and oxygen.

In the figure, the mark indicates the method of the present invention, and the mark ○ indicates the conventional atmospheric casting method.

As is clear from the figure, in the process up to the pouring process, there is almost no change in both nitrogen and oxygen in the conventional atmospheric casting method and the method of the present invention. In contrast, the values of both nitrogen and oxygen were high, and in particular, the value of oxygen was nearly double, whereas the method of the present invention showed a tendency to show slightly lower values after pouring.

From these results, it was found that sealing the atmosphere at the injection pipe entrance, which is the method of the present invention, is more effective in preventing contamination of the molten metal during pouring.

Example 2 In order to compare the conventional non-contamination casting method shown in FIG. 1 with the method of the present invention shown in FIG. 2, the oxygen concentration at the bottom of the injection tube, the argon gas flow rate, and the distance between the ladle and the injection tube were We investigated the relationship between

The results are shown in FIG.

The circle mark in the figure indicates the method of the present invention (the distance between the ladle and the injection pipe is irrelevant);
The mark MU indicates that the distance between the ladle and the injection pipe is 75 mm using the conventional method, and the mark Δ indicates that the distance between the ladle and the injection pipe is 150 mm using the conventional method.

As is clear from the figure, in the conventional method, the argon gas flow rate must be as large as 100 ONl/min in order to achieve the oxygen concentration at the bottom of the injection tube to 1st factor when the distance between the ladle and the injection tube is reduced to 75 mm. However, according to the method of the present invention, it has been found that the oxygen concentration at the bottom of the injection tube can reach as high as 0.8 by ejecting argon gas at a flow rate of only 14 ONl/min.

As described above, the present invention is an economical and effective non-contaminating casting method and apparatus with good casting workability and gas consumption of 115 or less compared to the conventional method, and is an invention of great industrial value. .

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a conventional non-contamination casting method. FIG. 2, FIG. 3, and FIG. 4 are diagrams showing one embodiment of the device of the present invention. FIG. 5 is a diagram showing changes in oxygen and nitrogen in molten steel and steel ingots. FIG. 6 is a diagram showing the argon gas flow rate and the oxygen concentration at the bottom of the injection tube. 1... Injection pipe, 2... Injection pipe brick, 3... Injection pipe funnel, 4... Injection pipe brick pressing sand, 5... Torus, 6...
Jet nozzle, γ...Gas conduit, 8...1 Non-oxidizing gas, 9...
...Pouring flow, 10...Ladle, 11...Gas blowing device, 12
...Distance between ladle and injection pipe, 13 ...Tundaishu, 1
4... Tandate nozzle, 15... Water cooling mold.

Claims (1)

[Scope of Claims] 1. In the process of casting molten metal, an injection pipe equipped with a torus having a gas outlet between the injection pipe funnel and the injection pipe brick is used, and the inside of the injection pipe brick is used from the gas outlet to the inside of the injection pipe brick. A non-contamination casting method characterized by injecting non-oxidizing gas into the liquid and pouring the metal in a non-oxidizing gas atmosphere. 2. A non-contamination casting device comprising a torus having a gas outlet between the injection pipe funnel and the injection pipe brick, and a conduit for introducing non-oxidizing gas into the torus. 3. The non-contamination casting apparatus according to claim 2, wherein the gas outlet is a torus made of a porous refractory material. 4. The non-contaminating casting apparatus according to claim 2, which is a toric body having a single spout. 5. The non-contamination casting apparatus according to claim 2, which is a toric body having a plurality of ejection ports.