JP2019072729A - Lower ingot making method - Google Patents

Abstract

To ensure prevention of entrainment of an in-die agent into molten steel during lower ingot making.SOLUTION: This lower ingot making method is characterized in that the bottom inner diameter of a cast 6 is set to 1000-2000 mm, and when molten steel is injected from the bottom inlet 5 of the cast 6, a runner 3 has a horizontal runner 4 which faces a horizontal direction in the bottom of the cast 6 and the inlet 5 which communicates with the horizontal runner 4 and faces a vertical direction and through which the molten steel is injected into the cast 6, the inlet 5 has a tapered diameter-expanded part 5a diameter-expanded upward at the end of the runner on the cast 6 side, the injection flow rate of the molten steel per inlet 5 is set to 1.5-3.0 t/min., a relationship between the inner diameter D1 [mm] of the horizontal runner 4 and the inner diameter D2 [mm] of the inlet 5 on the lower end side of the diameter-expanded part 5a satisfies (6.437×W+0.741×D1-10.849≤D2≤D1), a deviation amount d between the center of the inner diameter D2 and the center of the inner diameter D1 satisfies (0.08×D1≤d≤0.5×D1), the tapered angle θ of the diameter-expanded part 5a satisfies (2°≤θ≤8°), and the inner diameter D0 of the inlet 5 satisfies 1.8×D1≤D0≤2.5×D1.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a steel ingot by pouring a molten steel into the mold in a pouring manner to produce a steel ingot.

Conventionally, there are two types of ingot making methods for producing steel ingots using molds, from the difference in the pouring direction of molten steel, the "down pouring method" and the "up pouring method". The upper pouring method is a method of pouring molten steel from the ladle directly into the mold from the top of the mold.
On the other hand, the “down pouring method” was provided at the bottom of the mold through the horizontal runner from the runner vertically provided along the vertical direction at the end of the runner, and was directed vertically This is a method in which molten steel is poured from the lower side into the mold from the inlet so as to be ejected upward.

By the way, in the above-described “under pouring method” ingot-making method (hereinafter referred to as “in-pour-in-placement method”), the purpose is usually to prevent oxidation of molten steel, keep warm of molten steel, and prevent seizure of mold and solidified shell. In the mold, add a powdery mold interior agent (also called coating material or powder) to start casting.
However, in the case of the downward casting forging method in which the molten steel is ejected upward from the injection port at the mold bottom, the inward mold agent added into the mold is caught in the molten steel by the upward injection flow generated in the mold at the beginning of casting. May be trapped in the ingot.

If such an in-mold agent is involved in the molten steel, the in-mold agent may be trapped in the solidified shell of the bottom of the steel block, which may cause inclusion defects due to the in-mold agent. There is.
As a method of preventing such entrapment of the in-mold agent, there is a method of reducing the pouring speed of the molten steel at the initial stage of casting. However, at the initial stage of molten steel injection, since the temperature of the runner brick decreases, if the injection speed of molten steel is lowered, the molten steel solidifies inside the runner, and the solidified molten steel causes the runner to run. There is a risk of causing clogging.

Therefore, in order to solve the above-mentioned problems, in the conventional under cast and ingot method, means as shown in the following Patent Documents 1 to 4 are provided to prevent the entrapment of the in-mold agent.
For example, in Patent Document 1 in the pouring method of the molten metal under pouring system, the molten metal surface in the mold is stabilized during pouring without decreasing the pouring speed, and slags and non-metals are intervened. The mold-forming agent covering the surface of the hot water is suppressed by the molten steel that jets upward from the injection port while suppressing the inclusion of the material into the molten metal, and a portion of bare water called eyeball is generated and oxidized in the molten steel. It is an object of the present invention to improve the quality of a metal ingot by reducing the dispersion of non-metallic inclusions in the metal ingot which causes the quality of the metal ingot to be reduced.

  Specifically, in the pouring pipe used for the pouring method of the down pouring method, the pouring pipe which is a path of the molten metal which is in communication with the discharge port from the molten metal transport container and supplies the molten metal to the mold; One or more swirling flow forming means for forming a swirling flow in the molten metal is provided, and the flow velocity upward of the molten metal at the pouring pipe end decreases, and the discharge port by the centrifugal effect generated by the swirling flow By the diffusion of the molten metal from the metal, the fluctuation of the surface of the molten metal becomes smaller and becomes stable, and the phenomenon of rising up to the center part of the mold is greatly reduced to suppress the generation of eyes.

  According to Patent Document 2, when argon gas is used as the seal gas, the surface of the molten steel in the mold for the lower casting block is significantly fluctuated by the inclusion of the seal gas, and the molten steel in the mold for casting block is The surface of the molten steel is swayed or popped up on the surface of the molten steel, causing large fluctuations in the surface of the molten steel. As a result, the surface of the formed steel ingot becomes double skin, or the covering material covering the surface of the molten steel is wound and solidified to cause dents and roughening on the surface of the steel ingot etc. The purpose is to prevent the deterioration of the surface of the steel ingot.

  Specifically, in the pouring method in which molten steel is poured into horizontal casting channels on the left and right sides connected to the outlets provided on the left and right side walls of the lower end portion of the pouring pipe and poured down to the casting mold The molten steel is passed through a molten steel induction plate consisting of a helical swirling plate provided in the runner near the outlet to generate a swirling flow in the molten steel flowing through the runner, and it is poured into the mold for the lower casting block and rolled up. This is a pouring method in which bubbles of seal gas are dispersed and poured, and it is said that this method improves the surface texture of steel ingot.

  In Patent Document 3, bubbles of seal gas wound in the injection pipe are collected at the center of the runner by making the molten steel flowing in the runner a swirling flow, and a plurality of inflows into the casting mold for the lower casting are By dispersing it in the casting mold, the fluctuation of the surface of the molten steel in the casting mold is reduced, and the surface of the steel ingot is deteriorated and the surface of the molten steel is covered in the casting mold. The purpose is to prevent the entrapment of the covering material.

  Specifically, when flowing the molten steel from the ladle through the pouring pipe to the runner for the lower casting block, the molten steel is allowed to flow and drop from the upper inlet of the pouring pipe disposed vertically. In this case, a step is provided at the lower end of the injection tube, and the flow of molten steel is switched from vertical drop at the step and directed to the end of the step, and a downward drop provided at the end of the step The pipe section directs the flow of molten steel to the lower part in the direction of the pitting pipe section, and further, the outlet of the molten metal is disposed on the side wall of the pitting pipe section at the end of the step section located lower and closest to the extension of the bottom surface of the step section. By flowing molten steel in the horizontal direction runner, a swirling flow is generated in the runner, which is said to improve the surface surface of the steel ingot.

Patent Document 4 relates to a sub-casting apparatus for simultaneously producing a plurality of ingots by a plurality of sub-casting molds installed on a large surface plate, and more specifically, simultaneously producing ingots having different heights. The purpose is.
Specifically, when the molten metal is supplied into the injection pipe with the slide valves provided on the large surface plate in the open state, the molten metal passes through the horizontal runner in the large surface, and further Through a vertical runner in a double base plate, and simultaneously supplied into a plurality of molds on a large base plate. Then, the slide valve is closed in order from the molten metal in the mold having reached a predetermined level to shut off the runner in the double surface plate. Thereby, it is supposed that different height ingots can be manufactured by one large surface plate and one injection pipe.

Moreover, although it is not a supply technique of a molten metal like patent document 1-patent document 4, there also exists a technique which prevents entrapment of the in-mold agent by suppressing argon gas movement to a casting_mold | template.
In the case of a regular sub-casting block, between the funnel provided at the upper end of the injection pipe and the ladle, shut off with argon gas etc. to avoid oxidation of molten steel in the atmosphere and increase of inclusions Measures have been taken to prevent the infiltration of the atmosphere. However, since this argon gas does not dissolve in the molten steel, depending on the inner diameter of the injection pipe, the argon gas caught in the molten metal is brought into the mold through the injection pipe and the runner, and bubbles form in the molten steel in the mold. To rise. During the ascent, the bubble diameter of the argon gas increases as the static pressure of the molten steel decreases and the temperature increases toward the upper part of the mold (the time to float in the mold is as short as 2 to 3 seconds, so the growth of the bubble diameter (The influence of static pressure on the molten steel is considered to be greater than the influence of temperature)), when the bubbles of argon gas, which has become large, burst at the surface of the molten metal in the mold, the surface of the molten steel greatly vibrates and the vibration is large. And mold will be rolled up.

  Therefore, in Patent Document 5, the inner diameter of the injection pipe is increased to suppress migration of argon gas taken into the molten metal to the mold, thereby preventing vibration of the surface of the molten metal accompanying burst of bubbles of argon gas, Prevents the entrapment of the in-mold agent caused by the melt surface disorder.

JP 2007-216295 A JP, 2008-264816, A JP 2008-254058 A Japanese Patent Application Laid-Open No. 7-124699 Japanese Patent Laid-Open No. 2000-223260

By the way, in the conventional sub-casting ingot method, in order to suppress the inclusion of slags and non-metallic inclusions into the molten metal, there is a method of enlarging the inner diameter of the vertically oriented inlet, which is provided at the mold bottom. Proposed.
However, in the conventional techniques such as Patent Documents 1 to 4, the relationship between the injection port and the injection flow rate of molten steel is unknown. For example, if the inner diameter of the inlet is too large, the refractory provided at the inlet will need to be large, which will increase the cost of the refractory.

  There is also proposed a method of expanding the inner diameter toward the upper part of the injection port, that is, a method of providing a taper-shaped enlarged diameter portion which spreads upward to the injection port. Since the flow is separated from the inner peripheral wall of the inlet and the injection rate of molten steel does not decrease, the jet flow is not weakened. That is, the flow of molten steel into the mold does not diffuse. In addition, if the diameter-expanded portion is expanded, a large amount of refractory is required to be provided in the entire injection port, the cost of the refractory increases.

Therefore, the inventors of the present invention conducted intensive studies on the diffusion of the jet flow into the mold.
As a result, it has been found that the flow of molten steel, in particular the flow of molten steel as it swirls, is greatly involved in the diffusion of the jet flow.
By the way, in patent document 1, in order to give a swirling flow to the flow of molten steel, although the refractory which is made to act as a swirling wing is used in the runner, there is a possibility of the mixture of a fragment by breakage of the refractory. is there. Specifically, the spiral swirling vane may be broken by the impact of the injection flow, and the crushed material may be brought into the mold and taken into the molten steel to become an inclusion defect.

Therefore, if the thickness of the refractory acting as a swirling vane is increased in order to prevent breakage, the temperature rise of the refractory (swinging feather) in the initial stage of molten steel injection is delayed, so the temperature of the molten steel tends to decrease. There is a possibility that the injection flow (melted steel) will solidify inside and cause clogging of the runner at the turning wing.
In Patent Document 2, a swirling flow is to be imparted to the injection flow by means of a helical swirl plate provided in the injection pipe at a location distant from the mold injection port, but a large steel ingot is sought. In the case of manufacturing the above, if there is a distance from the spiral pivot plate to the mold, that is, the spiral pivot plate is far from the mold, the effect of imparting the swirl flow to the injection flow is weakened.

  In addition, the spiral swirl plate may be broken by the impact of the injection flow, and the crushed material may be brought into the mold and taken into the molten steel to cause inclusion defects. Therefore, if the thickness of the refractory acting as a swirling vane is increased in order to prevent breakage, the temperature rise of the refractory (swinging feather) in the initial stage of molten steel injection is delayed, so the temperature of the molten steel tends to decrease. There is a possibility that the injection flow (melted steel) will solidify inside and cause clogging of the runner at the turning wing.

In Patent Document 3, a swirling flow is to be imparted to the injection flow by the step portion provided in the injection pipe at a position distant from the mold injection port, but a large steel ingot is produced. In this case, if there is a distance from the step to the mold, that is, the step is far from the mold, the effect of imparting a swirling flow to the injection flow is weakened.
Also, when applying the technology of Patent Document 3 to the conventional inflow pouring and forming method, usually, the cast iron injection tube holding cylinder and the surface plate are modified to hold the refractory of the injection tube, that is, the mold Since it is necessary to remodel significantly, it leads to the cost increase of the production of steel ingots.

  In Patent Document 4, since the slide valve is operated at the final stage of molten steel injection, the diffusion of the injection flow into the mold in the initial stage of molten steel injection is not affected. That is, this technique is different from the object of the present invention because it has no effect of diffusing the jet flow into the mold. Even if the slide valve is operated at the initial stage of molten steel injection, the center of the horizontal runner and the mold inlet do not shift, so that the swirl flow does not occur and the effect is not expressed. In addition, the possibility of hot water leakage from the slide valve and the cost of the refractory due to the provision of the slide valve increase.

  Therefore, in the present invention, in view of the above problems, the flow rate of the molten steel to be injected into the mold is first defined when injecting the molten steel flowing through the horizontal runner into the mold from the injection port provided at the mold bottom. Keep the inside diameter of the inlet at least equal to or less than the inside diameter of the horizontal runner, and shift the center of the inlet from the center of the horizontal runner. Moreover, the enlarged diameter part made into the predetermined opening angle is provided in the inlet. In this way, a swirling flow can be imparted to the injection flow, and the injection flow can be injected so as to spread along the enlarged diameter portion, and the inclusion of the in-mold agent in the molten steel can be prevented to some extent .

However, deterioration of the mold surface skin by bubbles of argon gas sent to the mold can not be prevented only by means such as Patent Document 1 to Patent Document 4 described above, and it is possible to prevent the in-mold agent from being involved. It is not enough.
In this respect, the technique of Patent Document 5 mentioned above makes the inside diameter of the injection pipe thicker to make it difficult for argon gas to flow into the mold, but if the inside diameter of the injection pipe is unnecessarily thick, the steel solidified in the injection pipe becomes a product As it can not be used as a waste, it may be scrapped, which may lower the yield. In addition, since the refractory amount of the injection pipe is also increased, the initial investment of the facility may be increased. Therefore, the increase in the inner diameter of the injection pipe is preferably as small as possible.

Further, although the technique of Patent Document 5 considers the inner diameter of the injection pipe, it does not consider the inner diameter of the runner at all. Therefore, depending on the inner diameter of the runner, argon gas may flow into the mold.
Furthermore, the entrapment of the in-mold agent is particularly likely to also affect the entrapment of the in-mold agent at the beginning of casting, in other words, at the mold bottom, but considering the initial state of casting, the inner diameter of the injection pipe or runner Patent Document 5 does not mention at all how to make

  The present invention has been made in view of the above-mentioned problems, and it is possible not only to weaken the jet flow into the mold by providing a swirling flow to the injection flow but also to relate the inner diameter of the injection pipe to the inner diameter of the runner. In addition, the disturbance of the surface of the molten metal when the bubbles of argon gas burst at the surface of the molten metal is surely suppressed, and the inclusion of the in-mold agent does not occur in the entire range from the bottom of the mold to the top, and inclusion defects are reduced. It is an object of the present invention to provide an undercast forging method capable of producing high quality steel.

In order to achieve the above object, the following technical measures are taken in the present invention.
In the subcast ingot forming method according to the present invention, while pouring the molten steel through the runner from the inlet provided at the mold bottom to the mold whose inner diameter of the mold bottom is made 1000 mm to 2000 mm, pouring and forming the lower mass of the molten steel The runner has a horizontal runner facing in the horizontal direction at the bottom of the mold, an inlet communicating with the horizontal runner and facing in the vertical direction, and injecting the molten steel into the mold. The injection port has a tapered enlarged diameter portion that is expanded upward at the mold-side end of the runner, and the injection flow rate W of molten steel per injection port is 1.5 It injects so that it may be set to -3.0t / min, and the relationship between the inner diameter D1 [mm] of the horizontal runner and the inner diameter D2 [mm] of the inlet at the lower end side of the enlarged diameter portion is the formula (1 Meet the range shown in),
6. 437 × W + 0.741 × D1-10.849 ≦ D2 ≦ D1 (1)
However, W: Injection flow rate of molten steel per mold [t / min]
The amount of deviation d between the center of the inner diameter D2 and the center of the inner diameter D1 satisfies the range indicated by the equation (2),
0.08 × D1 ≦ d ≦ 0.5 × D1 (2)
The taper angle θ of the diameter-increasing portion with respect to the vertical direction satisfies the range indicated by equation (3),
2 ° ≦ θ ≦ 8 ° (3)
Assuming that the inner diameter of the injection pipe for supplying molten steel from the ladle to the horizontal runner is D0 [mm], the equation (4) is provided between the inner diameter D0 of the injection pipe and the inner diameter D1 of the horizontal runner. The relationship shown by is established
1.8 × D1 ≦ D0 ≦ 2.5 × D1 (4)
It is characterized by

  According to the present invention, not only the swirling flow is applied to the injection flow to weaken the jet flow into the mold, but also the relationship between the inner diameter of the injection pipe and the inner diameter of the runner is defined. It is possible to reliably suppress the disturbance of the surface of the molten metal at the time of rupture at the surface of the molten metal, and produce a high quality steel with no inclusion of the in-mold agent in the entire range from the bottom of the mold to the top. it can.

It is the model which showed the outline of the casting_mold | template and runner which are equipped with the under casting and forging apparatus. It is a schematic diagram of the water model which showed the lower casting forging apparatus provided with the conventional injection pipe and runner. It is a schematic diagram of the water model which showed the lower casting forging apparatus provided with the injection pipe and runner of this invention. It is the figure which showed typically the outline of the runner of this invention, Comprising: It is a figure which showed the outline of a horizontal runner, a pouring pipe, and an enlarged diameter part typically. When the pouring flow rate W is changed, it is the graph which showed the change of the number of ultrasonic defects in the bottom part of a steel ingot. It is the graph which showed the relationship between the pouring flow rate W in the lower part of a mold, and the amount level variation 2 (sigma) of hot water surface variation in the water surface directly on the inlet. When the pouring flow rate W is changed, it is the graph which showed the change of the number of ultrasonic defects in the top part of a steel ingot. It is the graph which showed the relationship between the pouring flow rate W in the upper part of a casting_mold | template, and water surface fluctuation amount 2 (sigma) in the water surface directly on the inlet. The situation of water surface fluctuation in the mold at the early stage of water injection assumed to be molten steel using the conventional nozzle and the mold at the early stage of water injection assumed to be molten steel using the improvement nozzle (invention) It is the image which compared and showed the condition of the water surface fluctuation in the inside. It is the graph which showed the result of having measured the water level change in the mold bottom part in the center part in a mold, when the water considered as molten steel using a conventional nozzle was poured. It is the graph which showed the result of having measured the water level change of the mold bottom at the end in a mold, when the water considered as molten steel using a conventional nozzle was injected. It is the graph which showed the result of having measured the water level change of the mold bottom in the central part in a mold, when the water considered as molten steel was injected using the improvement nozzle (swirling flow addition). It is the graph which showed the result of having measured the water level change of the mold bottom at the end in a mold, when the water considered as molten steel was injected using the improvement nozzle (swirl flow addition). It is the graph which showed the water surface fluctuation of the mold bottom in the mold inner-part center part at the time of using the conventional nozzle, and the relation of water surface height (corresponding to Drawing 9, Drawing 10). It is the graph which showed the water surface fluctuation of the mold bottom in the mold inner-part center part at the time of using an improvement nozzle (swirling flow addition), and the relation of water surface height (corresponding to Drawing 11 and Drawing 12). It is the figure which showed the shape of the conventional nozzle and the improvement nozzle (this invention) (only the inside of a refractory is shown). The situation of the water surface fluctuation of the upper part in the mold of the water regarded as molten steel using the injection pipe (D0 / D1 = 1.39) with a narrow inside diameter, the injection pipe with a wide inside diameter (the present invention) (D0 / D1 = 2.5) It is an image which showed the condition of the water level change of the upper part in a mold which used and looked like molten steel. The result of measuring the water surface fluctuation at the center of the upper part of the mold when water, which is assumed to be molten steel, is injected using an injection nozzle (D0 / D1 = 1.39) with a narrow inner diameter and using the improvement nozzle (invention) It is a graph shown. The result of measuring the water surface fluctuation at the upper end in the mold when water, which is assumed to be molten steel, is injected using an injection pipe (D0 / D1 = 1.39) with a narrow inner diameter and using the improvement nozzle (invention) It is a graph shown. The results of measuring the water surface fluctuation at the center of the upper part of the mold when water, which is regarded as molten steel, is injected using a large-diameter injection pipe (D0 / D1 = 2.5) and the improved nozzle (invention) It is a graph shown. The result of measuring the water surface fluctuation at the upper end in the mold when water, which is regarded as molten steel, is injected using a large-diameter injection pipe (D0 / D1 = 2.5) and the improved nozzle (invention) It is a graph shown. Using a thin injection tube (D0 / D1 = 1.39) with a narrow inner diameter, when water was poured into molten steel using a conventional nozzle (given only swirl flow), the water surface fluctuation at the top of the mold immediately above the injection port was measured It is the graph which showed the result. The result of measuring the water level fluctuation at the top of the mold directly above the injection port when water with a large internal diameter is injected using a large injection pipe (D0 / D1 = 2.5) and the improved nozzle (invention) is used. Is a graph showing The relationship between the injection flow rate W of molten steel per mold and the inner diameter D2 of the injection port when the variation 2σ of the surface level at the bottom of the mold does not exceed 32 mm in the case of the inner diameter D1 = 56 mmφ of the horizontal runner It is a graph shown. The relationship between the injection flow rate W of molten steel per mold and the inner diameter D2 of the injection port when the variation 2σ of the surface level at the bottom of the mold does not exceed 32 mm in the case of the inner diameter D1 = 64 mmφ of the horizontal runner It is a graph shown. The relationship between the injection flow rate W of molten steel per mold and the inner diameter D2 of the injection port when the variation 2σ of the surface level at the inner bottom of the mold does not exceed 32 mm when the inner diameter D1 of the horizontal runner = 72 mmφ It is a graph shown. The relationship between the injection flow rate W of molten steel per mold and the inner diameter D2 of the injection port when the variation 2σ of the surface level at the inner bottom of the mold does not exceed 32 mm when the inner diameter D1 of the horizontal runner is 80 mmφ. It is a graph shown. It is the graph which showed the relationship between the gradient a of the straight line which shows the internal diameter D1 of a horizontal runner, and a lower limit in FIGS. 23-26, and the segment b. The relationship between the ratio (d / D1) of the center displacement amount and the water surface fluctuation 2σ at the bottom of the mold in the case where the inner diameter D1 of the horizontal runner is 64 mm, the inner diameter D2 of the inlet is 56 mm, and the taper angle θ is 4 ° Is a graph showing The relationship between the ratio (d / D1) of the center displacement amount and the water surface fluctuation 2σ at the bottom of the mold in the case where the inner diameter D1 of the horizontal runner is 72 mm, the inner diameter D2 of the inlet is 60 mm, and the taper angle θ is 4 ° Is a graph showing The diameter expansion of the inlet in the case of the displacement d of the center of the inner diameter D1 of the horizontal runner and the center of the inner diameter D2 of the inlet d = 6.4 mm with the inner diameter D1 of the horizontal runner = 64 mm and the inner diameter D2 of the inlet = 56 mm It is the graph which showed the relationship between taper angle (theta) of a part, and water surface fluctuation amount 2 (sigma) of a mold bottom part. The diameter expansion of the inlet in the case of the displacement d of the center of the inner diameter D1 of the horizontal runner and the center of the inner diameter D2 of the inlet d = 6.4 mm with the inner diameter D1 of the horizontal runner = 72 mm and the inner diameter D2 of the inlet = 60 mm. It is the graph which showed the relationship between taper angle (theta) of a part, and water surface fluctuation amount 2 (sigma) of a mold bottom part. In the case of the displacement d of the center of the inner diameter D1 of the horizontal runner and the center of the inner diameter D2 of the injection hole d = 6.4 mm, the horizontal diameter of the injection conduit is horizontal and horizontal It is the graph which showed the relationship between the ratio (D0 / D1) of runner internal diameter, and water surface fluctuation amount 2 (sigma) of the mold upper part. In the case of the displacement d of the center of the inner diameter D1 of the horizontal runner and the center of the inner diameter D2 of the inlet d = 6.4 mm, the horizontal diameter of the horizontal runner is horizontal with the inner diameter of the injection tube It is the graph which showed the relationship between the ratio (D0 / D1) of runner internal diameter, and water surface fluctuation amount 2 (sigma) of the mold upper part. It is the figure which showed the outline of the template typically. It is the figure which showed typically the outline of the experiment apparatus which imitated the lower casting ingot apparatus used by water model experiment. It is the figure which showed typically the method to measure the water surface fluctuation | variation in a casting_mold | template.

Hereinafter, an embodiment of the submersible forging method according to the present invention will be described with reference to the drawings.
The embodiment described below is an example embodying the present invention, and the configuration of the present invention is not limited by the specific example.
According to the lower casting and forming method of the present invention, the molten steel 7 is passed through the runner 3 from the injection port 5 provided at the bottom of the mold 6 with respect to the mold 6 whose inner diameter at the bottom of the mold 6 is 1000 mm to 2000 mm. Under pouring and forming the molten steel 7 while pouring.

Now, there are two types of ingot making methods for producing a steel ingot using the mold 6 from the difference in the pouring direction of the molten steel 7 into the “down pouring method” and the “up pouring method”. The upper pouring method is a method of pouring the molten steel 7 from the ladle 9 directly into the mold 6 from the opening at the top of the mold 6.
On the other hand, in the “down pouring method”, as shown on the left side of FIG. 1, molten steel 7 is injected from the ladle 9 into the injection pipe 2 provided along the vertical direction, and the molten steel 7 is directed horizontally. It is provided on the bottom (plate) of the mold 6 via the horizontal runner 4 and sent to the inlet 5 facing vertically, and the molten steel 7 is spouted from the inlet 5 from the lower side. , Pouring into the mold 6.

  As shown in FIG. 1, the lower casting forging equipment 1 used in the lower casting forging method of the present invention is a horizontal runner 4 that faces horizontally in the bottom of the mold 6. And an inlet 5 (vertical runner) for injecting the molten steel 7 into the mold 6 while communicating with the horizontal runner 4 and facing in the vertical direction, and the inlet 5 in the runner 3 At the end portion on the mold 6 side, there is provided a tapered enlarged diameter portion 5a which is expanded upward.

The sub-casting and forming equipment 1 of the present embodiment is directed to an ingot mold 6 having a pouring amount of 40 t to 80 t for one mold of the mold 6, and the inner diameter of the bottom of the mold 6 from the plate thickness and rolling ratio of extremely thick products. Is set to 1000 mm to 2000 mm.
Moreover, in the subcast ingot mass method of this embodiment, the injection flow rate W of the molten steel 7 per piece of the inlet 5 is 1.5 t / min to 3.0 t / min. The molten steel 7 is injected into the mold 6 so as to be min.

The reason for defining the injection flow rate W of the molten steel 7 in such a range is as follows. That is, the present invention uses a water model experiment described later to confirm whether or not entrapment of the in-mold agent occurs. In this water model experiment, the experiment was performed with the range of the injection flow rate Q _M (subscript M represents a model) of water corresponding to the molten steel 7 per injection port 5 as 7 L / min to 13 L / min. Did.

Therefore, when the water injection flow rate Q _M of this water model experiment is converted to the injection flow rate Q _R (the subscript R represents the actual machine) of the molten steel 7 per injection port 5 in the actual machine, the molten steel 7 The injection flow rate W of 1.5 t / min to 3.0 t / min. That is, in the present invention, in the range of 1.5 t / min to 3.0 t / min of the injection flow rate W of the molten steel 7 per injection port 5, the relationships of the following formulas (1) to (4) hold And

In addition, since the pouring amount per 1 set of the molds 6 which this invention makes object is 40-80t as mentioned above, the range of casting time can also be prescribed | regulated to about 14 minutes-50 minutes.
As shown in FIG. 3, in the present embodiment, the relationship between the inner diameter D1 [mm] of the horizontal runner 4 and the inner diameter D2 [mm] of the inlet 5 at the lower end side of the enlarged diameter portion 5a is It is assumed that the range shown in) is satisfied.

6. 437 × W + 0.741 × D1-10.849 ≦ D2 ≦ D1 (1)
However, W: injection flow rate of molten steel per mold [t / min].
More specifically, the injection flow rate W of the molten steel 7 per mold 6 is a horizontal runner where the molten steel 7 injected from the nozzle provided at the bottom of the ladle 9 into the injection pipe 2 is branched and enters the mold The flow rate of the molten steel 7 injected into the inside is controlled by the slide valve provided at the nozzle, and the flow rate of the molten steel 7 is controlled.

Here, the diffusion of the injection flow (jet flow) into the mold will be described.
As shown in FIG. 1A, in the horizontal runner 4 and the inlet 5, the center of the horizontal runner 4 and the center of the inlet 5 are shifted at the portion where the flow of the molten steel 7 switches from the horizontal direction to the vertical direction. The vortices (swirling flow) are imparted to the pouring flow, and the spouting flow to which the swirling flow is imparted spreads along the tapered shape in the enlarged diameter portion 5a, whereby the jet flow (pouring flow) into the interior of the mold 6 The present inventors have learned that it is possible to weaken That is, it has been found that the flow of molten steel, in particular the flow of molten steel so as to swirl, is greatly involved in the diffusion of the jet flow.

The right view of FIG. 1A is an enlarged view of a portion A of a mold shown in the left view of the same view, and is a view in which the enlarged diameter portion 5a of the injection port 5 is provided.
As shown in the equation (1), when the inner diameter D2 of the inlet 5 is set to the same diameter as the inner diameter D1 of the horizontal runner 4 or a small diameter, and the centers of the horizontal runner and the inlet are shifted by a predetermined amount, A swirling flow is imparted to the flow, and an effect of spreading to the upper side of the mold 6 is developed.

However, when the inner diameter D2 of the inlet 5 is set to a diameter larger than the inner diameter D1 of the horizontal runner 4 (does not satisfy the equation (1)), the difference occurs between the center of the inlet 5 and the center of the horizontal runner 4 Generation of the vortex will be weakened. That is, no swirling flow is imparted to the injection flow.
On the other hand, if the inner diameter D2 of the inlet 5 is set to a diameter smaller than the value of the left side of the equation (1) (does not satisfy the equation (1)), the inner diameter of the inlet 5 becomes too thin. The upward flow velocity of the injection flow spouting into the nozzle increases, and the dispersion effect of the injection flow due to the generation of vortices disappears.

As for the lower limit value of the inner diameter D2 of the inlet 5, as the injection flow rate W of the molten steel 7 increases, it is necessary to increase the inner diameter D2 of the inlet 5 accordingly. Further, also by the diameter expansion of the inner diameter D1 of the horizontal runner 4, it is necessary to make the inner diameter D2 of the inlet 5 larger.
Further, in the present embodiment, the shift amount d [mm] of the center of the inner diameter D2 of the inlet 5 and the center of the inner diameter D1 of the horizontal runner 4 satisfies the range shown by the equation (2).

0.08 × D1 ≦ d ≦ 0.5 × D1 (2)
The shift amount d between the center of the inner diameter D2 of the inlet 5 and the center of the inner diameter D1 of the horizontal runner 4 is, for example, as shown in the arrow AA of FIG. 1B. The vertical axis (central axis) including the center is the amount shifted in the horizontal direction with respect to the vertical axis (central axis) including the center of the inner diameter D1 of the horizontal runner 4.

That is, the center of the inner diameter D2 of the inlet 5 and the center of the inner diameter D1 of the horizontal runner 4 are not aligned in the vertical direction.
The reason for setting the equation (2) is that if the deviation amount d between the center of the inner diameter D2 of the inlet 5 and the center of the inner diameter D1 of the horizontal runner 4 becomes smaller than (0.08 × D1) There is almost no occurrence of That is, if the equation (2) is not satisfied, the swirl flow is not imparted to the injection flow. Hereinafter, it is simply referred to as the center deviation amount d.

In addition, when the amount of deviation d at the center becomes larger than (0.5 × D1), the area of the joint between the refractory brick provided in the inlet 5 and the refractory brick provided in the horizontal runner 4 becomes It will decrease and the flow rate of the injection flow to the inlet 5 will increase. That is, if the equation (2) is not satisfied, the dispersion effect of the injection flow due to the generation of the vortex disappears.
Furthermore, in the present embodiment, the opening angle θ of the enlarged diameter portion 5a having a shape that opens upward in the injection port 5, that is, the taper angle θ of the enlarged diameter portion 5a in the vertical direction is It is supposed to satisfy the range shown.

2 ° ≦ θ ≦ 8 ° (3)
As the reason for setting the equation (3), when the molten steel 7 is injected into the mold 6, it is necessary to lower the injection flow rate and inject so as not to blow too much into the mold 6. As a countermeasure, as shown in FIG. 1B, the inside diameter of the injection port 5 provided with bricks in the periphery is made wider as it goes upward. That is, the enlarged diameter portion 5 a is provided in the injection port 5.

If the taper angle θ of the enlarged diameter portion 5a provided in the injection port 5 is 2 ° or more, the height of the raised portion is reduced.
However, if the taper angle θ is greater than 8 °, the injection flow is separated from the inner peripheral wall of the enlarged diameter portion 5a and does not spread along the taper angle. That is, if the equation (3) is not satisfied, the dispersion effect of the injection flow due to the generation of the vortex disappears.

Furthermore, in the present embodiment, when the inner diameter of the injection pipe 2 for supplying the molten steel from the ladle 9 to the horizontal runner 4 is D0 [mm], the inner diameter D0 of the injection pipe 2 and the inner diameter of the horizontal runner 4 The relationship shown by equation (4) is established between D1 and D1.
1.8 × D1 ≦ D0 ≦ 2.5 × D1 (4)
The reason for setting Formula (4) is to prevent Ar gas caught in the injection pipe 2 from being brought into the mold 6 while preventing cost increase and yield decrease.

  That is, when the inner diameter D0 of the injection pipe 2 is less than 1.8 times the inner diameter D1 of the horizontal runner 4 in the injection flow rate range of 1.5 t / min to 3.0 t / min, the injection pipe 2 is smaller than the horizontal runner 4 Since it becomes thin, the downward flow of the molten metal in the injection pipe 2 becomes large, and Ar gas caught in the injection pipe 2 may be brought into the mold 6. Further, even if the inner diameter D0 of the injection pipe 2 is larger than 2.5 times the inner diameter D1 of the horizontal runner 4, the effect of preventing Ar gas entrapment is almost the same. Refractory materials become large and cost increases. In addition, the yield will be deteriorated by the amount of steel in the injection pipe 2.

Next, the sub-casting method according to the present invention will be specifically described.
First, the determination of the limit value of the inclusion of the in-mold agent 8 into the molten steel 7 by the injection flow will be described.
As shown in FIG. 4, when the lower casting mass of 70 t steel ingot is performed using the nozzle 20 of the conventional shape, the injection flow rate (pouring flow rate) W of the molten steel 7 per injection port 5 In the case of 1.4 t / min or less, no ultrasonic defect was particularly recognized. However, when the injection flow rate W of the molten steel 7 per injection port 5 is 1.5 t / min or more, ultrasonic defects due to the inclusion of the in-mold agent 8 were observed at the bottom of the steel ingot. The ultrasonic defects were evaluated by an ultrasonic test in which a steel ingot was rolled to a thickness of 40 mm, and the number of ultrasonic defects generated in a range corresponding to 500 mm upward from the bottom of the steel ingot was measured.

The measuring equipment used in the ultrasonic test is as follows.
For the flaw detector, a digital ultrasonic flaw detector of model number UI-25 (manufactured by Ryoden Shonan Electronics Co., Ltd.) was used, and for a flaw detector, model number 2C30N was used. In addition, the flaw detection sensitivity was set using a standard test piece (STB-G V15-2.8 (JIS)) at a ridge echo height of 80%.
Further, as shown in FIG. 5, the number of ultrasonic defects was also measured for the top portion by the ultrasonic test, as in the case of the bottom portion of the steel ingot described above. That is, at the late stage of casting, when the surface of the molten metal rises and reaches just below the pouring portion of the mold, argon gas bubbles caught in the molten metal expand and burst at the maximum. At this time, the surface fluctuation due to the bubble burst is also maximized. Therefore, with respect to the top portion of the steel ingot, the ultrasonic test was evaluated by an ultrasonic test in which the upper portion of the steel ingot was rolled to a thickness of 40 mm and the number of ultrasonic defects was measured. In addition, the top part of a steel ingot is a range corresponded to 1800-2200 mm from a mold bottom part.

  Also at the top of the steel ingot, ultrasonic defects due to the inclusion of the in-mold agent 8 were observed. That is, when the injection flow rate (pouring flow rate) W of molten steel 7 per injection port 5 is 1.4 t / min or less, ultrasonic defects are not particularly recognized, but the injection flow rate (pouring flow rate) W is If it is larger than 1.4 t / min, ultrasonic defects will be recognized. From this, it is judged that no ultrasonic defects due to the inclusion of the in-mold agent 8 will occur if the injection flow rate (pouring flow rate) W is set to 1.4 t / min or less at the bottom and the top of the steel ingot. .

On the other hand, if a water model experiment to be described later is performed, it is possible to investigate the relationship between the pouring flow rate to the mold and the amount 2σ of fluctuation in the surface of the water immediately above the inlet.
For example, FIG. 5 shows the relationship between the bottom portion of steel ingot, in other words, the molten metal surface fluctuation amount 2σ obtained by converting the injection flow rate in the water model test into the pouring flow rate in an actual machine at the initial stage of casting. Referring to FIG. 5, the fluctuation amount of the water surface increases with the increase of the pouring flow rate. Here, since the flow rate of the injection port 5 in which the ultrasonic defect did not occur is 1.4 t / min or less from the result of FIG. 3, the pouring flow rate draws a boundary line of 1.4 t / min in the figure, If we look at the value of the amount of fluctuation 2σ of the water surface, where is less than 1.4 t / min, the value of 2σ is 32 mm. Therefore, it was judged that ultrasonic defects do not occur (the problem of entrapment of the in-mold agent does not occur) when the fluctuation amount 2σ of the water surface height is 32 mm or less.

  Further, similarly to FIG. 5, FIG. 6 also shows the relationship between the pouring flow rate and the surface level variation 2σ within the range equivalent to 1800 to 2200 mm from the top of the steel ingot, in other words, from the bottom of the mold 6. . Looking at FIG. 6, similarly to FIG. 5, when looking at the value of the fluctuation amount 2σ of the water surface at which the pouring flow rate is 1.4 t / min or less, the value of 2σ is 32 mm. From this fact, there is no concern that ultrasonic defects will occur when the water surface height variation amount 2σ is 32 mm or less at the bottom of the steel ingot or at the top of the steel ingot, and the problem of mold entrapment is also included. I decided not to occur.

In the actual casting, the in-mold agent 8 is in the form of powder, is wrapped in a plastic bag, and is wrapped with a thick paper (a paper material used for thick envelopes) from above the plastic bag. It is Such an in-mold agent 8 wrapped in a bag, paper or the like is tied with a wire and is hung from the upper end of the mold 6 by a chain.
As such a mold internal agent, one having a component composition as shown in Table 1 can be used, for example. The in-mold agent of Table 1 is powdery and softens at 1090 to 1210 ° C. The softening of the in-mold agent means the case where the powder on the surface of the sample disappears and is in a bulging state when heated in a refractory container made of alumina.

Before pouring the molten steel 7, the mold interior agent 8 wrapped in a bag, paper or the like is set at a position 100 mm to 200 mm above the bottom of the mold 6. Then, when the molten steel 7 is injected into the mold 6, the in-mold agent 8 is heated by the heat of the molten steel 7, the cardboard and the vinyl are heated and burnt first, and then the in-mold agent 8 falls into the mold 6. It will be.
In such a procedure, the powdery in-mold agent 8 is added to the mold 6 to start casting.

In addition, the water model experiment described above was conducted in the manner as shown below. In addition, about this water model test result, it has shown using the pouring flow volume, the amount of hot water surface variation, and length which were converted into the real machine.
First, a method of measuring the water surface fluctuation 2σ will be described.
In the measurement of the water surface fluctuation amount 2σ, the water surface fluctuation in the container simulating the mold 6 is performed by the ultrasonic displacement sensor 10. As points to measure the water surface fluctuation 2σ, the position immediately above the injection port 5, and the injection port 5 (a position 820 mm away from the inner wall of the mold 6) and the middle position of the mold 6 wall (from the inner wall of the mold 6) And two points (center and end in the mold 6).

FIG. 8 shows the water surface fluctuation state when water assumed to be the molten steel 7 was injected into the container (the mold 6) with the injection flow rate W of the molten steel 7 per mold of the mold 6 being 2.46 t / min. In addition, FIG. 8 is a verification image which imaged the water surface fluctuation | variation in the casting_mold | mold 6 in the early stage of casting. The inner diameter ratio (D0 / D1) obtained by dividing the inner diameter D0 of the injection pipe 2 by the inner diameter D1 of the horizontal runner is 1.39.
The left image in FIG. 8 shows that the conventional nozzle 20 (inside diameter D1 of horizontal runner D = 72 mm.phi., Inside diameter D2 of the inlet 5 = 72 mm.phi.) Without eccentricity (no deviation between the center of D2 and the center of D1) or diameter expansion. It is the image which showed the condition of the water surface variation in the casting_mold | mold 6, when using the left figure of FIG. 15).

The right image in FIG. 8 shows the improved nozzle 5 (horizontal runner) of the present invention (having an enlarged diameter portion 5 a) by narrowing the inlet 5 and expanding the eccentricity (there is a gap between the center of D 2 and the center of D 1) The water surface in the mold 6 when using the inner diameter D1 of 4 = 72 mmφ, the inner diameter D2 of the inlet 5 = 60 mmφ, the shift amount d of the center = 6.4 mm, the taper angle θ = 4 ° (see the right figure in FIG. 15) It is the image which showed the condition of change.
Referring to FIG. 8, an improvement nozzle (an improved nozzle having an enlarged diameter portion 5 a which is eccentric to the center of the inner diameter D 2 of the inlet 5 with respect to the center of the inner diameter D 1 of the horizontal runner 4 and expanded upward) By using the injection port 5) of the invention, it can be seen that the buildup of the injection flow immediately above the nozzle is reduced at the initial stage of the injection of the molten steel 7. That is, when the injection port 5 of the present invention is used, as described later, even if the inside diameter ratio (D0 / D1) obtained by dividing the inside diameter D0 of the injection pipe 2 by the inside diameter D1 of the horizontal runner is less than 1.8, Water surface fluctuations can be reduced.

FIG. 9 shows the result of measuring the water surface fluctuation at the central portion in the mold 6 when the water assumed to be the molten steel 7 was injected using the conventional nozzle 20. FIG. 10 shows the result of measuring the water surface fluctuation at the end portion in the mold 6 when the injection of water assumed to be the molten steel 7 is performed using the conventional nozzle 20.
FIG. 11 shows the result of measurement of water surface fluctuation at the center of the mold 6 when water assumed to be the molten steel 7 was injected using the improvement nozzle 5. FIG. 12 shows the result of measuring the water surface fluctuation at the end of the mold 6 when the improvement nozzle 5 is used to inject water regarded as the molten steel 7. The experimental conditions in FIGS. 9, 10, 11, and 12 are the same as in the case of the verification image shown in FIG.

  As shown in FIG. 11, when the injection of water regarded as molten steel 7 is carried out using the improvement nozzle 5, the result is compared with the result of the injection of water regarded as molten steel 7 using the conventional nozzle 20 shown in FIG. Thus, it can be seen that the water level fluctuation particularly in the center of the mold 6, that is, just above the inlet 5 is reduced. Moreover, when FIG. 10 and FIG. 12 are compared, also in the edge part in the casting_mold | mold 6, it turns out that the water surface fluctuation | variation is smaller when the improvement nozzle 5 is used.

That is, when the center of the inner diameter D2 of the inlet 5 is eccentric to the center of the inner diameter D1 of the horizontal runner 4 and the enlarged diameter portion 5a is expanded upward, the effect of suppressing the water surface fluctuation is remarkable. It is.
Subsequently, a method of measuring the water surface fluctuation amount 2σ at each water surface height in the mold 6 by the injection flow spouted from the injection port 5 will be described.
The fluctuation of the water surface immediately above the inlet 5 was measured at intervals of 0.1 sec (corresponding to 0.2 sec in an actual machine). On the other hand, the water surface fluctuation measured at the middle position between the inlet 5 and the mold 6 wall is measured at intervals of 0.1 sec (corresponding to 0.2 sec in actual equipment), and the rising speed of the water surface is obtained from the time averaged value. The water surface position (the distance from the bottom of the mold 6) was determined.

In addition, the surface level variation 2σ is twice the standard deviation σ of the difference between the instantaneous height of the water surface immediately above the inlet 5 that is fluctuating rapidly and the average value of the water surface position at each time measured at the mold end. And
FIG. 13 shows an example of the relationship between the water surface fluctuation directly above the inlet and the water surface height from the bottom of the mold 6 when using the conventional nozzle 20 (see FIG. 15 left drawing) (FIGS. 9 and 10) Correspondence). FIG. 14 shows an example of the relationship between the water surface fluctuation amount immediately above the inlet and the water surface height from the bottom of the mold 6 when the improvement nozzle 5 (see FIG. 15 right drawing) is used (FIGS. 11 and 12) Correspondence).

As shown in FIG. 14, when the molten steel 7 is injected using the improvement nozzle 5, it is understood that the water surface fluctuation is significantly reduced compared to the use of the conventional nozzle 20 shown in FIG. 13. Since there are some variations in the experimental results, an average of 2σ was obtained from the results repeated three times for each experimental condition, and the effect of the nozzle (injection port 5) was evaluated using the 2σ as the amount of water surface fluctuation.
Next, the relationship between the inner diameter D1 of the horizontal runner 4, the inner diameter D2 of the injection port 5, the injection flow rate W of the molten steel 7 per mold 6 and the amount of fluctuation of molten metal level 2σ will be described. Hereinafter, in the case of the water model, it is also simply referred to as the hot-water level variation 2σ.

  When a water model experiment is conducted, the condition in which eccentricity and diameter expansion are performed so that the amount of molten metal fluctuation 2σ in the water surface height just above the injection port 5 becomes 32 mm or less in the mold 6 (center The injection flow rate W of molten steel 7 per mold 6 or horizontal runner 4 even if the improvement nozzle d of the amount of deviation d = 6.4 mm and the taper angle θ = 4 ° of the enlarged diameter portion 5 a) is used. It has been found that depending on the values of the inner diameter D1 and the inner diameter D2 of the injection port 5, the surface level fluctuation amount 2σ of the water level just above the injection port 5 does not necessarily satisfy 32 mm or less.

Therefore, a verification experiment was performed by changing the injection flow rate W of the molten steel 7 per mold 6 and the inner diameter D1 of the horizontal runner 4 and the inner diameter D2 of the injection port 5.
In this verification experiment, the injection flow rate Q _{M of} water was changed to 7 L / min, 9 L / min, 11 L / min, and 13 L / min. When this value is converted into an actual machine, the injection flow rate W of the molten steel 7 per one mold 6 corresponds to 1.57 t / min, 2.02 t / min, 2.46 t / min, and 2.91 t / min.

23 to 26 show the results of the above-mentioned verification experiment.
FIG. 23 shows the injection flow rate W of molten steel 7 per mold 6 and the inner diameter D2 of the injection port 5 when the molten metal level variation 2σ does not exceed 32 mm in the case of the internal diameter D1 = 56 mmφ of the horizontal runner 4. It is the graph which showed the relation. FIG. 24 shows the injection flow rate W of molten steel 7 per mold 6 and the inner diameter D2 of the injection port 5 when the molten metal level variation 2σ does not exceed 32 mm in the case of the inner diameter D1 = 64 mmφ of the horizontal runner 4. It is the graph which showed the relation.

  FIG. 25 shows the injection flow rate W of molten steel 7 per mold 6 and the inner diameter D2 of the injection port 5 when the molten metal level variation 2σ does not exceed 32 mm when the internal diameter D1 of the horizontal runner 4 is 72 mmφ. It is the graph which showed the relation. FIG. 26 shows the injection flow rate W of molten steel 7 per mold 6 and the inner diameter D2 of the injection port 5 when the molten metal level variation 2σ does not exceed 32 mm when the inner diameter D1 of the horizontal runner 4 is 80 mmφ. It is the graph which showed the relation.

In FIG. 23 to FIG. 26, the case where the surface level variation 2σ is 32 mm or less due to the injection flow spouted from the injection port 5 is indicated by ○, and the other case is indicated by x There is.
Here, an apparatus configuration of the lower casting and ingot forming apparatus 1 for casting a steel ingot will be described.
As shown in FIG. 34, the sub-casting and forming apparatus 1 has a refractory material disposed inside a cast iron disc called a surface plate, and a cast iron injection pipe 2 which is long in the vertical direction. Are arranged, and one or more cast iron ingot cases (mold 6) are arranged on the side of the box. In the present embodiment, one in which one mold 6 is disposed on the side of the injection pipe 2 is taken as an example.

In order to lead the molten steel 7 injected from the injection pipe 2 to the mold 6, a horizontal runner 4 whose flow path is directed in the horizontal direction is provided in a surface plate which is a bottom of the mold 6. The horizontal runner 4 is a refractory pipe connecting between the injection pipe 2 disposed substantially at the center of the platen and the injection port 5 provided at the center of the bottom of the mold 6 of each mold 6.
The horizontal runner 4 is made of brick such as chamotte, and the inner diameter of the brick is defined as the inner diameter D1 [mm]. Further, the inlet 5 (vertical runner) is also made of brick such as chamotte, and the inner diameter of the brick at the lower end of the enlarged diameter portion 5a is defined as the inner diameter D2 [mm].

Next, the derivation process of equation (1) showing the relationship between the inner diameter D1 [mm] of the horizontal runner 4 and the inner diameter D2 [mm] of the inlet 5 on the lower end side of the enlarged diameter portion 5a will be described.
FIGS. 23 to 26 show the results of verification experiments in the case where the inner diameter D1 of the horizontal runner 4 is 56 mmφ, 64 mmφ, 72 mmφ, and 80 mmφ. In FIG. 23 to FIG. 26, the values of the gradient a and the segment b of the straight line equation (showing the relationship between the inner diameter D2 of the inlet 5 and the injection flow rate W of molten steel 7 per mold 6) showing the lower limit are It changes with the value of the internal diameter D1 of the horizontal runner 4.

The relationship between the values of the gradient a and the intercept b and the inner diameter D1 of the horizontal runner 4 is as shown in FIG.
Referring to FIG. 27, the gradient a is hardly affected by the inner diameter D1 of the horizontal runner 4 and has a substantially constant average value of 6.437. On the other hand, the intercept b is shown by the relationship of b = 0.7407 × D1−10.849. Therefore, the lower limit (left side of the equation (1)) of the inner diameter D2 of the inlet 5 is defined as follows.

6.437 × W + 0.741 × D1-10.849
From the above results, the range of the inner diameter D2 of the injection port 5 in which the amount of molten metal surface variation 2σ is 32 mm or less is the formula (1).
6. 437 × W + 0.741 × D1-10.849 ≦ D2 ≦ D1 (1)
From these results, the upper limit of the inner diameter D2 of the injection port 5 is equal to or less than the inner diameter D1 of the horizontal runner 4 regardless of the injection flow rate W of the molten steel 7 per mold 6. Further, the lower limit of the inner diameter D2 of the injection port 5 increases with the increase of the injection flow rate W of the molten steel 7 per mold 6 and is expressed by the equation (1).

That is, as the injection flow rate W of the molten steel 7 per mold 6 increases, the inner diameter D2 of the injection port 5 needs to be increased so that the molten metal surface variation 2σ becomes 32 mm or less.
The same relationship was shown when the values (W, D1, D2) were in the optimum range, even if the center displacement amount d was 6.4 mm and the taper angle θ was 4 °.
D2 = 6.437 × W + 0.741 × D1-10.849
Subsequently, the relationship between the center shift amount d and the hot water level variation 2σ, that is, the derivation process of the equation (2) will be described.

  The inside diameter D1 of the horizontal runner 4 = 64 mm, the inside diameter D2 of the injection port 5 = 56 mm, and the taper angle in a range where the injection flow rate W of the molten steel 7 per mold 6 is equivalent to 1.57-2.91 t / min in a real machine In the case of θ = 4 °, the center displacement amount d is varied in the range of 0 to (0.5 × D1), that is, 0 to 32 mm, and the center displacement amount ratio (d / D1) The relationship of the fluctuation 2σ was investigated. An example of the surveyed result is shown in FIG.

  In addition, the inner diameter D1 of the horizontal runner 4 = 72 mm, the inner diameter D2 of the inlet 5 = 60 mm, in the range where the injection flow rate W of the molten steel 7 per mold 6 is equivalent to 1.57-2.46 t / min in an actual machine. In the case of the taper angle θ = 4 °, the ratio (d / D1) of the central deviation amounts by changing the central deviation amount d in the range of 0 to (0.5 × D1), that is, 0 to 36 mm; FIG. 29 shows an example of the result of investigation of the relationship between the surface level fluctuation amount 2σ.

Referring to FIG. 29, in the case where the injection flow rate W of molten steel 7 per one mold of casting mold 6 is 2.91 t / min, the formula for inner diameter D1 of horizontal runner 4 = 72 mm and inner diameter D2 of injection port 5 = 60 mm I excluded because I did not satisfy 1).
In either case of FIG. 28 and FIG. 29, the surface level variation 2σ decreases as the ratio (d / D1) of the center offset amount increases. Further, when the ratio (d / D1) of the center displacement amount is 0.08 or more, the hot water surface fluctuation amount 2σ, which is the limit value of the entrapment of the in-mold agent 8, becomes 32 mm or less.

It should be noted that when the ratio (d / D1) of the center displacement amount is smaller than 0.08, the hot water level fluctuation amount 2σ becomes large because the occurrence of vortices (swirling flow) hardly occurs.
On the other hand, when the ratio (d / D1) of the displacement amount at the center becomes larger than 0.5, the refractory brick disposed in the inlet 5 and the refractory brick disposed in the horizontal runner 4 The area of the joint decreases, the flow velocity of the molten steel 7 to the injection port 5 increases, and the surface level fluctuation 2σ increases.

In addition, also in actual casting, if the center displacement amount d is made larger than (0.5 × D1), significant modification of the surface plate portion of the mold 6 is required, which causes problems of labor and cost.
That is, if the center shift amount d is in the above-mentioned range, the horizontal runner 4 and the periphery of the inlet 5 are only slightly remodeled, so that the labor and cost can be largely reduced.
In addition, when the ratio (d / D1) of the center deviation amount is less than 0.08, the hot water level fluctuation amount 2σ becomes large.

Based on the above results, the same results as described above were obtained when the taper angle θ of the expanded diameter portion 5a is implemented under the condition satisfying the formula (1) in the range of 2 ° to 8 °.
Therefore, in addition to the above conditions, if the center shift amount d satisfies the equation (2), the hot water level variation 2σ can be set to 32 mm or less.
0.08 × D1 ≦ d ≦ 0.5 × D1 (2)
Furthermore, the relationship between the taper angle θ of the enlarged diameter portion 5a and the amount of fluctuation of molten metal surface 2σ, that is, the derivation process of the equation (3) will be described.

The injection flow rate W of molten steel 7 per mold 6 is in the range of 1.57 to 2.91 t / min in an actual machine, the inner diameter D1 of the horizontal runner 4 = 64 mm, the inner diameter D2 of the injection port 5 = 56 mm, and the center displacement amount In the case of d = 6.4 mm, the taper angle θ of the enlarged diameter portion 5a was changed between 0 ° and 12 °, and the relationship between the taper angle θ and the surface level variation 2σ was investigated. An example of the surveyed result is shown in FIG.
In the case where the injection flow rate W is in the range of 1.57 to 2.46 t / min in a real machine, the inner diameter D1 of the horizontal runner 4 = 72 mm, the inner diameter D2 of the injection port 5 = 60 mm, and the center deviation d = 6.4 mm, The taper angle θ of the enlarged diameter portion 5a was changed between 0 and 12 °, and the relationship between the taper angle θ and the amount of fluctuation of molten metal surface 2σ was investigated. An example of the surveyed result is shown in FIG.

Referring to FIG. 31, when the injection flow rate W of molten steel 7 per mold of casting mold W = 2.91 t / min, the formula for inner diameter D1 of horizontal runner 4 = 72 mm and inner diameter D2 of injection port 5 = 60 mm, I excluded because I did not satisfy 1).
In either case of FIGS. 30 and 31, as the taper angle θ becomes larger (open), the amount of fluctuation of molten metal surface 2σ becomes smaller. Further, when the taper angle θ is 2 ° or more, the hot-water level fluctuation 2σ, which is the limit value of the entrapment of the in-mold agent 8, is 32 mm or less. In addition, when the taper angle θ becomes larger than 2 °, the surface level variation 2σ decreases.

On the other hand, when the taper angle θ is less than 2 ° and more than 8 °, the surface level variation 2σ becomes larger than 32 mm.
Based on the above results, the same results as described above can be obtained when the taper angle θ of the enlarged diameter portion 5a is implemented under the condition satisfying the expressions (1) and (2) in the range of 2 ° to 8 °. The
Therefore, if the equation (1) and the equation (2) are satisfied and the relationship of the equation (3) is satisfied, it is possible to set the molten metal surface variation 2σ to 32 mm or less.

2 ° ≦ θ ≦ 8 ° (3)
When the enlarged diameter portion 5a is provided on the upper side of the injection port 5 and the taper angle θ is in the above range, a vortex is wound on the flow of the molten steel 7 flowing from the horizontal runner 4 into the injection port 5 It was observed that the swirling flow (injection flow) spreads upward in the injection state, that is, the swirl flow is applied to the injection flow, and in the injection port 5 (the enlarged diameter portion 5a) (for example, FIG. See the right figure of).

However, even if the other test conditions are within the condition range of this test (water model test), if the taper angle θ exceeds 8 °, the flow (vortex) of molten steel 7 has the inlet 5 wall (diameter increase) Since it does not separate from the tapered inner wall surface of the portion 5a and does not spread, that is, the eddy current does not spread along the enlarged diameter portion 5a, the amount of fluctuation of molten metal surface 2σ increases.
Although Formula (1)-Formula (3) mentioned above provided swirling flow with respect to the injection flow, and were prevented from being caught in the mold in the mold, the lower cast mass of the present invention The method also defines the relationship of equation (4) in order to suppress the movement of bubbles of argon gas caught in the molten metal to the mold side.

Next, the relationship between the inner diameter D0 of the pouring pipe 2 for supplying molten steel from the ladle to the horizontal runner and the inner diameter D1 of the horizontal runner, that is, the derivation process of the equation (4) will be described.
In FIG. 16, the injection flow rate W of the molten steel 7 per mold 6 was 2.46 t / min, and the situation of the water surface fluctuation when water regarded as the molten steel 7 was injected into the container (mold 6) was shown. FIG. 16 is a verification image obtained by imaging the water surface fluctuation in the mold 6 when the inner diameter of the injection tube 2 is changed.

  The left image in FIG. 16 shows the case where a narrow conventional injection pipe is used such that the inner diameter ratio (D0 / D1) obtained by dividing the inner diameter D0 of the injection pipe 2 by the inner diameter D1 of the horizontal runner is 1.39. It is the image which showed the condition of the water surface fluctuation in a mold. The nozzle for supplying the molten metal to the mold is the improved nozzle 5 of the present invention (inside diameter D1 of horizontal runner 4 = 72 mmφ, inside diameter D2 of injection port 5 = 60 mmφ, center deviation d = 6.4 mm, taper angle In the injection pipe 2, a small diameter (conventional injection pipe 2) having an inner diameter D0 of 100 mm was used.

  The right side image in FIG. 16 shows the case where a thick injection pipe 2 according to the present invention is used such that the inside diameter ratio (D0 / D1) obtained by dividing the inside diameter D0 of the injection pipe 2 by the inside diameter D1 of the horizontal runner is 2.5. It is the image which showed the condition of the water surface fluctuation in the mold 6. The nozzle for supplying the molten metal to the mold is the improved nozzle 5 of the present invention (inside diameter D1 of horizontal runner 4 = 72 mmφ, inside diameter D2 of injection port 5 = 60 mmφ, center deviation d = 6.4 mm, taper angle The injection pipe 2 is a large diameter (invention pipe 2 according to the present invention) having an inner diameter D0 of 180 mm.

  Referring to FIG. 16, by using a thick injection pipe 2 (injection pipe 2 of the present invention) having a large internal diameter ratio to the internal diameter D1 of horizontal runner 4 of 2.5, in the later stage of molten steel injection, directly above the nozzle It can be seen that the rise of the injection flow is decreasing. That is, the use of the large diameter injection pipe 2 of the present invention can reduce the water surface fluctuation in the mold (during casting upper part) in the late stage of casting.

FIG. 17 shows the result of measurement of water surface fluctuation at the upper center of the mold 6 when the molten steel 7 is moved to the mold using the conventional injection pipe 2 having a narrow inner diameter. FIG. 18 shows the result of measurement of water surface fluctuation at the upper end in the mold 6 when the molten steel 7 is moved to the mold using the conventional injection tube 2 having a narrow inner diameter.
FIG. 19 shows the result of measuring the water surface fluctuation at the upper central portion in the mold 6 when the molten steel 7 is moved to the mold using the injection pipe 2 of the present invention having a large inner diameter. FIG. 20 shows the result of measurement of water surface fluctuation at the upper end in the mold 6 when the molten steel 7 is moved to the mold using the injection pipe 2 of the present invention having a large inner diameter. The experimental conditions in FIGS. 17, 18, 19, and 20 are the same as in the case of the verification image shown in FIG.

  As shown in FIG. 19, when the molten steel 7 is moved to the mold using the injection pipe 2 of the present invention, compared to the result of moving the molten steel 7 to the mold using the conventional injection pipe 2 shown in FIG. In particular, it can be seen that the water surface fluctuation at the center of the mold 6, that is, immediately above the inlet 5 is reduced. Moreover, when FIG. 20 and FIG. 18 are compared, it turns out that a water surface fluctuation | variation is smaller also at the edge part in the casting_mold | template 6 also when this invention injection pipe 2 is used.

That is, water surface fluctuation can be effectively suppressed by using the large diameter injection pipe 2 with which the inside diameter ratio (D0 / D1) is 1.80 or more.
When the amount of water surface fluctuation at each water surface height in the upper part of the mold 6 is measured by the same method as in FIGS. 13 and 14 described above, results as shown in FIGS. 21 and 22 can be obtained.
FIG. 21 shows an example of the relationship between the water surface fluctuation amount and the water surface height from the mold bottom when using the conventional injection pipe (inner diameter ratio = 1.39) (corresponding to FIGS. 17 and 18). FIG. 22 shows an example of the relationship between the water surface fluctuation amount and the water surface height from the bottom of the mold 6 when using the improved injection pipe 2 (inside diameter ratio = 2.5) (corresponding to FIGS. 19 and 20) .

  As shown in FIG. 22, it can be seen that when the molten steel 7 is moved to the mold using the improved injection pipe 2, the water surface fluctuation is significantly smaller than in the case of using the conventional injection pipe shown in FIG. . In addition, although the measured value is described only to the water surface height from the mold 6 bottom in FIG. 22 to 2200 mm, the applicant confirms that the water surface fluctuation is very small even at the water surface height of 2200 mm or more. .

Next, the derivation process of equation (4) showing the relationship between the inner diameter D0 [mm] of the injection pipe 2 and the inner diameter D1 [mm] of the horizontal runner 4 will be described.
The injection flow rate W of molten steel 7 per mold 6 is in the range of 1.57 to 2.91 t / min in an actual machine, the inner diameter D1 of the horizontal runner 4 = 64 mm, the inner diameter D2 of the injection port 5 = 56 mm, and the center displacement amount In the case of d = 6.4 mm and taper angle θ = 4 ° of enlarged diameter portion 5a, the inner diameter ratio (inner diameter D0 of injection pipe 2 / inner diameter D1 of horizontal runner) is changed between 1.60 to 2.80, and the inner diameter ratio And, the relationship between the amount of hot water fluctuation 2σ was investigated. An example of the surveyed result is shown in FIG.

  In addition, the injection flow rate W is in the range of 1.57 to 2.46 t / min in the actual machine, the inner diameter D1 of the horizontal runner 4 = 72 mm, the inner diameter D2 of the injection port 5 = 60 mm, the center deviation d = 6.4 mm, the enlarged diameter portion In the case of the taper angle θ = 4 ° of 5a, the inner diameter ratio (inner diameter D0 of injection pipe 2 / inner diameter D1 of horizontal runner) is changed between 1.40 and 2.50, and the inner diameter ratio and the molten metal surface fluctuation 2σ I investigated the relationship. An example of the surveyed result is shown in FIG.

In either case of FIG. 32 and FIG. 33, as the inner diameter ratio is larger (opened), the amount of liquid level fluctuation 2σ is smaller. In addition, when the inside diameter ratio is 1.80 or more, the hot-water level fluctuation 2σ, which is the limit value of the entrapment of the in-mold agent 8, is 32 mm or less. Further, even if the inside diameter ratio is larger than 2.50, the amount of fluctuation of molten metal level 2σ is already sufficiently reduced, and a new decrease hardly occurs.
On the other hand, if the inside diameter ratio is less than 1.80 and exceeds 2.50, the molten metal level variation 2σ will be greater than 32 mm, or the injection tube 2 with a large inside diameter will be adopted even though the effect can not be expected. Is not preferable because it causes

Based on the above results, casting is performed under conditions that satisfy the relationship of equation (1) to equation (3) with the relationship of equation (4) that sets the inside diameter ratio to 1.8 or more and 2.5 or less. If implemented, the molten metal surface variation 2σ can be set to 32 mm or less, and it is possible to cast an ingot with no inclusion of the in-mold agent from the early casting stage to the late casting stage and having almost no ultrasonic defects.
1.8 × D1 ≦ D0 ≦ 2.5 × D1 (4)
[Example]
In the following, examples of water model experiments carried out according to the subcast-in-lump method of the present invention and comparative examples carried out for comparison with the present invention will be described.

First, the definition of the experimental conditions and parameters of the water model experiment will be described.
Water model experiments were performed using a 1⁄4 scale model.
As for the similarity condition, the Froude number Fr is matched.
Fr = V / (gL) ^0.5
However, V: flow velocity [m / s], L: length [m], g: gravitational acceleration [m / s ² ]
Assuming that the fluid flow velocity is V, the representative dimension is L, the kinematic viscosity is ν, the fluid viscosity is Fr, the Reynolds number is Re, and the gravity acceleration is g, as well known, for similar conditions of water model experiments. It becomes a formula to show.

Fr = V / (g × L) ^0.5
Re = LV / ν
Then, when the equation of motion is made dimensionless, “(inertial term) + (viscous term) / Re + (external force term) = 0” is obtained, and Fr is substituted for the external force term by (1 / Fr ² ). As Re becomes larger, (the viscosity term) / Re becomes smaller, Re is eliminated from the equation of motion.

In Re> 4000 or more, it is usually considered as a turbulent flow region, and Fr number approximation can be used. In the range specified in the present invention, since Re> 5000, a turbulent flow region is obtained, and the Fr number approximation is applied.
About the structure of the experiment apparatus which imitated the lower casting ingot apparatus 1 used by water model experiment, it is as follows.

As shown in FIG. 35, the experimental apparatus 1 is in communication with the injection pipe 2 facing in the vertical direction, the horizontal runner 4 in communication with the injection pipe 2 and facing in the horizontal direction, and the horizontal runner 4 It consists of a container 5 imitating a mold 6 in communication with the inlet 5 (vertical runner) facing in the vertical direction and capable of storing water regarded as the molten steel 7.
Water imitating molten steel 7 is injected into the injection pipe 2 from the funnel portion 2a provided at the upper portion of the injection pipe 2 while surrounding air is taken in. This is the same situation even in a real machine, and in order to prevent the oxidation of the molten steel 7, an argon gas atmosphere is established between the ladle 9 and the funnel portion 2a.

In an actual machine, a state where argon gas is caught in the injection pipe 2, the horizontal runner 4, the injection port 5 and the mold 6 by the injection flow from the ladle 9 is also realized by a water model experiment. I am doing it.
The container imitating the mold 6 is an upper spread mold, which is one-fourth the size of a 70 t steel ingot mold in an actual machine, and is manufactured by a transparent resin mold. The dimensions of the container 6 are a bottom surface: 412 mmφ, an upper surface: 500 mmφ, a height from the bottom surface to the lower end of the pouring portion: 665 mm, and a height from the bottom surface to the top of the injection pipe 2a 1060 mm.

  The inner diameter D0 of the injection pipe 2 is 25 mm, 30 mm, 32 mm, 33 mm, 35 mm, 40 mm, 45 mm. In addition, when it converts into a real machine, it corresponds to 100 mmφ, 120 mmφ, 128 mmφ, 132 mmφ, 140 mmφ, 160 mmφ, 180 mmφ. The injection tube 2 is a Teflon (registered trademark) tube processed or coated with Teflon (registered trademark), and the funnel portion 2a is attached to the upper portion.

The horizontal runner 4 had a length of 443 mm, and a plurality of inner diameters D1 of 14 mmφ, 16 mmφ, 18 mmφ, and 20 mmφ were prepared and used. When converted to a real machine, the length corresponds to 1772 mm, and the inner diameter D1 corresponds to 56 mmφ, 64 mmφ, 72 mmφ, and 80 mmφ.
As the injection port 5, a plurality of bores having inner diameters D2 of 10 mmφ, 11 mmφ, 12 mmφ, 13 mmφ, 14 mmφ, 15 mmφ, 16 mmφ, 17 mmφ, 18 mmφ, 19 mmφ, 20 mmφ, 21 mmφ were used. In addition, it corresponds to 40 mmφ, 44 mmφ, 48 mmφ, 52 mmφ, 60 mmφ, 64 mmφ, 68 mmφ, 72 mmφ, 76 mmφ, 80 mmφ, 84 mmφ in terms of actual equipment.

About the ratio (d / D1) of the gap | deviation amount of a center, it was set as 0, 0.05, 0.08, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6. Further, the taper angle (opening angle) θ of the enlarged diameter portion 5a is 0 °, 2 °, 4 °, 6 °, 8 °, 10 °, 12 °.
As for the length L1 of the vertical portion 5b of the inlet 5, a plurality of pieces such as 15 mm, 22.5 mm, and 35 mm were prepared and used. In addition, it will correspond to 60 mm, 90 mm, and 140 mm when converted to a real machine. Moreover, about length L 2 of the enlarged diameter part 5a, several things, such as 72.5 mm, 65 mm, and 52.5 mm, were prepared and used. In addition, it will correspond to 290 mm, 260 mm, and 210 mm when converted to a real machine.

From the above, (length L1 of vertical portion 5b + length L2 of enlarged diameter portion 5a) is 87.5 mm at maximum, which corresponds to 350 mm in actual equipment.
In addition, in this experiment, although (L1 + L2) is implemented in the case of 350 mm, if it is inferred from the generation method of the eddy current (injection flow + swirling flow), (L1 + L2) is about 500 mm, It is considered that the same function and effect as the present invention can be obtained.

The inlet 5 is provided in one place in the mold 6 (container).
The injection flow rate W of the molten steel 7 per injection port 5 is as follows.
The injection flow rate Q _{M of} water regarded as molten steel 7 per injection port 5 in the water model experiment was 7.0 L / min, 9.0 L / min, 11.0 L / min, 13.0 L / min. In addition, when converted to a real machine, the injection flow rate W of the molten steel 7 per one mold of the mold 6 corresponds to 1.57 t / min, 2.02 t / min, 2.46 t / min, and 2.91 t / min.

The procedure of converting the water model flow rate Q _M [L / min] into the injection flow rate W [t / min] of molten steel 7 per mold 6 in a real machine was converted by Froude number approximation.
The Froude number Fr is expressed by the following equation.
Fr = V / (g × L) ^0.5
However, V: water flow velocity [m / s], L: representative length [m], g: gravitational acceleration [m / s ² ]
The Froude number of the actual machine in ingot under pouring and casting is matched with the Froude number of water model experiment.

The representative dimensions of the actual machine and the representative dimension ratio of the water model experiment are set to 4: 1. That is, in the case of a 1⁄4 scale model, it is necessary to make (V / L ^0.5 ) the same value from the viewpoint of Froude number coincidence.
Assuming that the scale is 1 / λ (= 1/4), it is shown as follows. Here, the subscript R indicates a real machine, and the subscript M indicates a model.
V _R / L _R ^0.5 = V _M / L _M ^0.5
V _M / V _R = L _M ^0.5 / L _R ^0.5 = 1 / λ ^0.5 = 1/4 ^0.5 = 0.5
V _M = 0.5 V _R
Therefore, when the flow velocity V _M in a 1⁄4 scale water model experiment is 0.5 times the flow velocity V _{R in} the actual machine, the Fr number agreement can be obtained.

Also, assuming that the injection flow rate of the molten steel 7 per injection port 5 is Q and the time is T, it is shown as follows.
T _R = L _R / V _R
T _M = L _M / V _M
T _R = T _M · L _R / L _M · V _M / V _R = T _M λ ^0.5
Q _M / Q _R = (L _M ³ / T _M ) / (L _R ³ / T _R ) = λ ⁻³ · λ ^0.5 = λ ^−2.5
From the above results, the injection flow rate Q _{M of} water regarded as molten steel 7 per injection port 5 in the water model experiment is the injection flow rate Q _R of molten steel 7 per injection port 5 in an actual machine. It becomes 1/4 ^2.5 = 0.0313 times.

In addition, the injection flow rate Q _M [L / min] of molten steel 7 per injection port 5 in the water model experiment is compared with the injection flow rate W [t / min] of molten steel 7 per mold 6 in an actual machine. In the case where the specific gravity of the molten steel 7 is 7 t / m ³ , the formula (A) is obtained.
W = 7 × Q _M /(0.0313×10 ³ ) = 0.224 × Q _M (A)
In the water model test, an electromagnetic flowmeter is attached to the pipe 2b before injecting water regarded as the molten steel 7 from the funnel portion 2a, and the electromagnetic flowmeter measures the molten steel 7 per injection port 5 The injection flow rate Q _{M of} water was estimated.

About the measurement method of the surface level variation in the mold 6 (container), about 200 mm from the bottom of the mold 6 about the measurement of the mold bottom at a position just above the injection port 5 and 50 mm (200 mm in actual machine) from the mold 6 wall The ultrasonic displacement sensor 11 was placed above (about 800 mm in the actual machine) and about 675 mm (about 2700 mm in the actual machine) from the bottom of the mold 6 for measurement of the top of the mold.
In addition, about the measurement of the above-mentioned change of a surface, it is an ultrasonic type displacement which consists of a sensor head 11a (product number: UD-310) and an amplifier unit 11b (product number: UD-300) manufactured by Keyence Corporation. The measurement was performed using two sensors, and the measurement data was stored in the data logger 12.

Tables 2 to 16 show examples of water model experiments carried out according to the subcast ingot method of the present invention and comparative examples carried out to compare with the present invention.
Tables 2 to 5 show the influence of the injection flow rate W of the molten steel 7 per one mold of the mold 6, the inner diameter D1 of the horizontal runner 4 and the inner diameter D2 of the injection port 5 in the actual machine on the melt surface fluctuation 2σ. The effects of the inner diameter ratio (D0 / D1) are summarized. The length L1 of the vertical portion 5b is 60 mm, the length L2 of the enlarged diameter portion 5a is 290 mm, the taper angle θ is 4 °, and the center deviation d is 6.4 mm or 7.2 mm.

  Regarding Experiment No. 2 in Table 2, the injection flow rate W of the molten steel 7 per one mold 6 in an actual machine is 1.57 t / min. Further, since the inner diameter D1 of the horizontal runner 4 is 56.0 mm and the inner diameter D2 of the inlet 5 is 44.0 mm, the inequality (D2 ≦ D1) on the right side of the equation (1) is satisfied. Further, since the left side of the equation (1) is calculated to be 40.7 mm, D2 becomes 44.0 mm or less, and the relationship of the equation (1) is satisfied. In other words, Experiment No. 2 satisfies the equation (1).

In addition, since the gap | deviation amount d of a center is 6.4 mm, Experiment No. 2 is satisfying | fulfilling Formula (2). Further, since the taper angle θ is 4 °, the experiment number 2 satisfies the equation (3).
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 56.0 mm, the inner diameter ratio is 100/56 = 1.79, and the inner diameter ratio is the lower limit of equation (4) Is less than 1.80. That is, Experiment No. 2 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The results similar to those of Experiment No. 2 are the experiment Nos. 2, 3, 4, 5, 8, 9, 10, 11, 15, 16, 17, 22, 23, 26, 27, 28, 29, 30 in Table 2. And so on.

On the other hand, for Experiment No. 19, since the left side of Formula (1) is calculated to be 49.4 mm, the left side of Formula (1) exceeds D2 = 40.0 mm, and thus Formula (1) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 41.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also 1.79, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

  The same results as those of Experiment No. 19 are obtained for Experiment Nos. 1, 6, 7, 12, 13, 14, 18, 19, 20, 21, 24, 25, 31 and so on in Table 2, and The fluctuation control effect is not good.

  Regarding Experiment No. 34 in Table 3, the injection flow rate W of molten steel 7 per one mold 6 in an actual machine is 2.02 t / min. In addition, since the inner diameter D1 of the horizontal runner 4 is 64.0 mm and the inner diameter D2 of the inlet 5 is 52.0 mm, the experiment number 34 satisfies the inequality (D2 ≦ D1) on the right side of the equation (1). Further, since the left side of the equation (1) is calculated to be 49.6 mm, the left side of the equation (1) becomes 52.0 mm or less, and the experiment number 34 satisfies the relationship of the equation (1).

In addition, since the gap | deviation amount d of a center is 6.4 mm, Experiment No. 34 is satisfying | fulfilling Formula (2). Further, since the taper angle θ is 4 °, the experiment No. 34 also satisfies the equation (3).
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 64.0 mm, the inner diameter ratio is 100/64 = 1.56, and the inner diameter ratio is the lower limit of equation (4) Is less than 1.80. That is, the experiment No. 34 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as those of Experiment No. 34 are also obtained for Experiment Nos. 35, 36, 37, 42, 43, 44, 49, 50, 51, 54, 55, 56, 57, 58 and so on in Table 3.

On the other hand, for the experiment number 46, since the left side of the equation (1) is calculated to be 55.3 mm, D2 = 44.0 mm is exceeded, so the equation (1) is not satisfied. As a result, the amount of molten metal surface variation 2σ at the bottom of the mold becomes 40.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also 1.56, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

  The same results as those of Experiment No. 46 are obtained for Experiment Nos. 32, 33, 38, 39, 40, 41, 45, 47, 48, 52, 53, 59 and so on in Table 3. The suppression effect is not good.

  Regarding Experiment No. 64 in Table 4, the injection flow rate W of molten steel 7 per one mold 6 in an actual machine is 2.02 t / min. In addition, since the inner diameter D1 of the horizontal runner 4 is 72.0 mm and the inner diameter D2 of the inlet 5 is 68.0 mm, the experiment number 64 satisfies the inequality (D2 ≦ D1) on the right side of Equation (1). Further, since the left side of Formula (1) is calculated to be 55.5 mm, D2 = 68.0 mm or less, and the experiment number 64 satisfies the inequality on the left side of Formula (1). That is, the experiment number 64 will satisfy the relationship of Formula (1).

In addition, since the gap | deviation amount d of the center is 6.4 mm, Formula (2) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 72.0 mm, the inner diameter ratio is 100/72 = 1.39. Less than. That is, the experiment number 64 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as in this experiment No. 64 are for experiment Nos. 61, 62, 63, 65, 69, 70, 71, 72, 77, 78, 79, 82, 83, 84, 85, 86, 87, etc. Is also obtained.

On the other hand, for the experiment number 74, since the left side of the equation (1) is calculated to be 61.2 mm, D2 = 52.0 mm is exceeded, so the equation (1) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 39.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also 1.56, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

  The same result as the experiment No. 74 is obtained for the experiment Nos. 60, 66, 67, 68, 73, 75, 76, 80, 81, 88, etc. It has become nothing.

  Regarding Experiment No. 93 in Table 5, the injection flow rate W of molten steel 7 per one mold 6 in an actual machine is 2.02 t / min. Further, since the inner diameter D1 of the horizontal runner 4 is 80.0 mm and the inner diameter D2 of the inlet 5 is 76.0 mm, Experiment No. 93 satisfies the inequality (D2 ≦ D1) on the right side of the equation (1). Further, since the left side of the equation (1) is calculated to be 61.4 mm, D2 = 76.0 mm or less, and the experiment number 93 satisfies the inequality on the left side. That is, the experiment number 93 will satisfy the relationship of Formula (1).

In addition, since the gap | deviation amount d of the center is 7.2 mm, Formula (2) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 80.0 mm, the inner diameter ratio is 100/80 = 1.25. Less than. That is, the experiment number 93 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as those of Experiment No. 93 are also obtained for Experiment Nos. 90, 91, 92, 94, 98, 99, 100, 101, 105, 106, 107, 108 and the like of Table 5.

On the other hand, for the experiment number 103, since the left side of the equation (1) is calculated to be 67.2 mm, D2 = 60.0 mm is exceeded, so the equation (1) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 38.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also lower than the lower limit value of 1.25 (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

The same result as the experiment No. 103 is obtained also for the experiment Nos. 89, 95, 96, 97, 102, 104, 109, etc. in Table 5, and the effect of suppressing the fluctuation of the surface level is not good. .
Tables 6 and 7 show the influence of the injection flow rate W of the molten steel 7 per unit of the mold 6, the inner diameter D1 of the horizontal runner 4 and the inner diameter D2 of the injection port 5 in the actual machine on the melt surface fluctuation 2σ. The effects of the inner diameter ratio (D0 / D1) are summarized. The length L1 of the vertical portion 5b is 90 mm, the length L2 of the enlarged diameter portion 5a is 260 mm, the taper angle θ is 4 °, and the center deviation d is 6.4 mm or 7.2 mm.

  Regarding Experiment No. 202 in Table 6, the injection flow rate W of the molten steel 7 per one mold 6 in an actual machine is 1.57 t / min. In addition, since the inner diameter D1 of the horizontal runner 4 is 64.0 mm and the inner diameter D2 of the inlet 5 is 48.0 mm, the experiment number 202 satisfies the inequality (D2 ≦ D1) on the right side of Equation (1). Further, since the left side of the equation (1) is calculated to be 46.7 mm, D2 = 48.0 mm or less, and the experiment number 202 satisfies the inequality on the left side. That is, the experiment number 202 will satisfy the relationship of Formula (1).

In addition, since the gap | deviation amount d of the center is 6.4 mm, Formula (2) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 64.0 mm, the inner diameter ratio is 100/64 = 1.56, which is the lower limit of Equation (4), 1.80. Less than. That is, the experiment number 202 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as those of Experiment No. 202 are also obtained for Experiment Nos. 203, 204, 205, 206, 210, 211, 212, 213, 218, 219, 220, 225, 226, 227 and the like in Table 6.

On the other hand, for the experiment number 222, since the left side of the equation (1) is calculated to be 55.3 mm, D2 = 44.0 mm is exceeded, so the equation (1) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 41.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also 1.56, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

  The same results as those of Experiment No. 222 are obtained for Experiment Nos. 201, 207, 208, 209, 214, 215, 216, 217, 221, 223, 224, 228, etc. The suppression effect is not good.

  Regarding Experiment No. 233 in Table 7, the injection flow rate W of the molten steel 7 per one mold 6 in an actual machine is 1.57 t / min. In addition, since the inner diameter D1 of the horizontal runner 4 is 80.0 mm and the inner diameter D2 of the inlet 5 is 72.0 mm, the experiment number 233 satisfies the inequality (D2 ≦ D1) on the right side of the equation (1). Further, since the left side of the equation (1) is calculated to be 58.5 mm, D2 = 72.0 mm or less, and the experiment number 233 satisfies the inequality on the left side. That is, the experiment number 233 will satisfy the relationship of Formula (1).

In addition, since the gap | deviation amount d of the center is 7.2 mm, Formula (2) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 80.0 mm, the inner diameter ratio is 100/80 = 1.25. Less than. That is, the experiment number 233 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as those of Experiment No. 233 are shown in Experiment No. 230, 231, 232, 234, 235, 238, 239, 240, 241, 242, 246, 248, 249, 253, 254, 255, 256 of Table 7. And so on.

On the other hand, for the experiment number 251, since the left side of the equation (1) is calculated to be 67.2 mm, D2 = 60.0 mm is exceeded, so the equation (1) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 39.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also lower than the lower limit value of 1.25 (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

Results similar to those of Experiment No. 251 are obtained also for Experiment Nos. 229, 236, 237, 243, 244, 245, 250, 252, 257, etc. in Table 7, and the effect of suppressing the fluctuation of the surface level is not good It has become.
Tables 8 and 9 show the influence of the injection flow rate W of the molten steel 7 per one mold of the mold 6, the inner diameter D1 of the horizontal runner 4 and the inner diameter D2 of the injection port 5 in the actual machine on the melt surface fluctuation 2σ. The effects of the inner diameter ratio (D0 / D1) are summarized. The length L1 of the vertical portion 5b is 140 mm, the length L2 of the enlarged diameter portion 5a is 210 mm, the taper angle θ is 4 °, and the amount of deviation of the center d is 6.4 mm or 7.2 mm.

  Regarding Experiment No. 302 in Table 8, the injection flow rate W of the molten steel 7 per one mold 6 in an actual machine is 1.57 t / min. Further, since the inner diameter D1 of the horizontal runner 4 is 64.0 mm and the inner diameter D2 of the injection port 5 is 48.0 mm, the experiment number 302 satisfies the inequality (D2 ≦ D1) on the right side of the equation (1). Further, since the left side of the equation (1) is calculated to be 46.7 mm, D2 = 48.0 mm or less, and the experiment number 302 satisfies the inequality on the left side. That is, the experiment number 302 will satisfy the relationship of Formula (1).

In addition, since the gap | deviation amount d of the center is 6.4 mm, Formula (2) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 64.0 mm, the inner diameter ratio is 100/64 = 1.56, which is the lower limit of Equation (4), 1.80. Less than. That is, the experiment number 302 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same result as the experiment No. 302 is obtained also for the experiment Nos. 303, 304, 305, 306, 310, 311, 312, 313, 318, 319, 320, 325, 326, 327 in Table 8.

On the other hand, for the experiment number 322, since the left side of the equation (1) is calculated to be 55.3 mm, D2 = 44.0 mm is exceeded, so the equation (1) is not satisfied. As a result, the amount of variation in molten metal surface 2σ at the bottom of the mold becomes 42.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also 1.56, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

  The same results as those of Experiment No. 322 are obtained for Experiment Nos. 301, 307, 308, 309, 314, 315, 316, 317, 321, 323, 324, 328, etc. The suppression effect is not good.

  Regarding Experiment No. 333 in Table 9, the injection flow rate W of the molten steel 7 per one mold 6 in an actual machine is 1.57 t / min. Further, since the inner diameter D1 of the horizontal runner 4 is 80.0 mm and the inner diameter D2 of the inlet 5 is 72.0 mm, the experiment number 333 satisfies the inequality (D2 ≦ D1) on the right side of the equation (1). Further, since the left side of the equation (1) is calculated to be 58.5 mm, D2 = 72.0 mm or less, and the experiment number 333 satisfies the inequality on the left side. That is, the equation (1) is satisfied.

In addition, since the gap | deviation amount d of the center is 7.2 mm, Formula (2) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 80.0 mm, the inner diameter ratio is 100/80 = 1.25. Less than. That is, the experiment number 333 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The results similar to this experiment No. 333 are the experiment Nos. 330, 331, 332, 334, 335, 338, 339, 340, 341, 342, 346, 347, 348, 353, 354, 355, 356 of Table 9. And so on.

On the other hand, with regard to Experiment No. 351, since the left side of Formula (1) is calculated to be 67.2 mm, D2 = 60.0 mm is exceeded, and thus Formula (1) is not satisfied. As a result, the amount of molten metal surface variation 2σ at the bottom of the mold becomes 40.0 mm, which greatly exceeds 32 mm.
In addition, the inside diameter ratio is also lower than the lower limit value of 1.25 (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.

The same results as those of Experiment No. 351 are obtained also for Experiment Nos. 329, 336, 337, 343, 344, 345, 350, 352, 357, etc. of Table 9, and the effect of suppressing the fluctuation of the surface level is not good. It has become.
Tables 10 and 11 summarize the influence of the center deviation amount d and the influence of the inner diameter ratio (D0 / D1) on the surface level variation 2σ. The length L1 of the vertical portion 5b is 60 mm, the length L2 of the enlarged diameter portion 5a is 290 mm, and the taper angle θ is 4 °, which is constant.

For Experiment No. 406 in Table 10, the inner diameter D1 of the horizontal runner 4 is 64.0 mm. Moreover, it is 0.08xD1 = 5.12 mm and is 0.5xD1 = 32 mm. The shift amount d of the center is 25.6 mm, which satisfies the equation (2).
In the actual machine, the injection flow rate W of the molten steel 7 per one mold of the mold 6 is 1.57 t / min, and the inner diameter D2 of the injection port 5 is 56.0 mm. Moreover, the left side of Formula (1) is calculated with 46.7 mm. Thereby, the equation (1) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.

However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 64.0 mm, the inner diameter ratio is 100/64 = 1.56, which is the lower limit of Equation (4), 1.80. Less than. That is, the experiment number 406 does not satisfy the equation (4).
Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.

The results similar to those of this experiment No. 406 are the same as the experiment Nos. 403, 404, 405, 407, 411, 35, 412, 413, 414, 415, 423, 420, 421, 422, 423, 427, 49 in Table 10. , 428, 429, 430, 431 and so on.
On the other hand, for the experiment number 425, the center shift amount d is 0 mm, that is, “no shift”, and of course the formula (2) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 47.0 mm, which greatly exceeds 32 mm.

In addition, the inside diameter ratio is also 1.56, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.
The same results as those of Experiment No. 425 are obtained also for Experiment Nos. 401, 402, 408, 409, 410, 416, 417, 418, 424, 426, 432, etc. Is a bad thing.

For Experiment No. 439 in Table 11, the inner diameter D1 of the horizontal runner 4 is 72.0 mm. Further, 0.08 × D1 = 5.76 mm and 0.5 × D1 = 36 mm. The shift amount d of the center is 36.0 mm, which satisfies the equation (2).
In the actual machine, the injection flow rate W of molten steel 7 per mold 6 is 1.57 t / min, the inside diameter D2 of the injection port 5 is 60.0 mm, and the left side of the equation (1) is calculated to be 52.6 mm. Ru. Thereby, the equation (1) is satisfied. Further, since the taper angle θ is 4 °, the equation (3) is satisfied.

However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 72.0 mm, the inner diameter ratio is 100/72 = 1.39. Less than. That is, Experiment No. 439 does not satisfy Formula (4).
Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.

The same results as those of Experiment No. 439 are shown for Experiment Nos. 55, 435, 436, 437, 438, 62, 443, 445, 446, 447, 69, 451, 452, 453, 454, 455, etc. Is also obtained.
On the other hand, about experiment number 448, the internal diameter D1 of the horizontal runner 4 is 72.0 mm. Further, 0.08 × D1 = 5.76 mm and 0.5 × D1 = 36 mm. The center displacement amount d is 43.2 mm, and the expression (2) is not satisfied. As a result, the molten metal surface variation 2σ is 38.0 mm, which greatly exceeds 32 mm. That is, the effect of suppressing the fluctuation of the surface of the mold at the bottom of the mold is not expressed.

In addition, the inside diameter ratio is also 1.39, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all.
The same results as those of Experiment No. 448 are obtained for Experiment Nos. 433, 434, 440, 441, 442, 449, 450, 456, etc. in Table 11, and the effect of suppressing the fluctuation of the surface level is not good. ing.

  Tables 12 and 13 summarize the influence of the taper angle θ of the diameter-increasing part 5a and the influence of the inner diameter ratio (D0 / D1) on the surface level variation 2σ. The length L1 of the vertical portion 5b is 60 mm, the length L2 of the enlarged diameter portion 5a is 290 mm, and the amount of deviation d of the center d is 6.4 mm.

For the experiment number 502 in Table 12, the taper angle θ is 2 °, which satisfies the equation (3).
In the actual machine, the injection flow rate W of the molten steel 7 per mold 6 is 1.57 t / min. Further, the inner diameter D1 of the horizontal runner 4 is 64.0 mm, and the inner diameter D2 of the inlet 5 is 56.0 mm. Moreover, the left side of Formula (1) is calculated with 46.7 mm. Thereby, the equation (1) is satisfied. Further, since the center shift amount d is 6.4 mm, the equation (2) is satisfied.

However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 64.0 mm, the inner diameter ratio is 100/64 = 1.56, which is the lower limit of Equation (4), 1.80. Less than. That is, the experiment number 502 does not satisfy the equation (4).
Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.

Similar results to this experiment No. 502 are also obtained for experiment Nos. 28, 503, 504, 508, 35, 509, 510, 514, 42, 515, 516, 520, 49, 521, 522, etc. in Table 12. There is.
On the other hand, with regard to Experiment No. 506, since the taper angle θ is 12 °, the equation (3) is not satisfied. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 45.0 mm, which greatly exceeds 32 mm. That is, the suppression effect of the surface fluctuation is not expressed.

In addition, the inside diameter ratio is also 1.56, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all.
The same results as those of Experiment No. 506 are obtained also for Experiment Nos. 501, 505, 507, 511, 512, 513, 517, 518, 519, 523, 524 and the like in Table 12, and the effect of suppressing water level fluctuation Is a bad thing.

For the experiment number 528 in Table 13, the taper angle θ is 8 °, which satisfies the equation (3).
In the actual machine, the injection flow rate W of the molten steel 7 per mold 6 is 1.57 t / min. Further, the inner diameter D1 of the horizontal runner 4 is 72.0 mm, and the inner diameter D2 of the inlet 5 is 60.0 mm. Moreover, the left side of Formula (1) is calculated with 52.6 mm. Thereby, the equation (1) is satisfied. Further, since the center shift amount d is 6.4 mm, the equation (2) is satisfied.

However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 100.0 mm and the inner diameter D1 of the horizontal runner is 72.0 mm, the inner diameter ratio is 100/72 = 1.39. Less than. That is, the experiment number 528 does not satisfy the equation (4).
Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.

Similar results to Experiment No. 528 are also obtained for Experiment Nos. 526, 55, 527, 532, 62, 533, 534, 538, 69, 539, 540, etc. in Table 13.
On the other hand, for the experiment number 525, since the taper angle θ is 0 °, the equation (3) is not satisfied. That is, it does not have the enlarged diameter part 5a. As a result, the amount of variation of molten metal surface 2σ at the bottom of the mold becomes 44.0 mm, which greatly exceeds 32 mm.

In addition, the inside diameter ratio is also 1.39, which is lower than the lower limit value of equation (4). Therefore, the movement of bubbles of argon gas to the mold side can not be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface can not be expected at all. Therefore, the suppression effect of the hot water level fluctuation is not good.
The same results as those of Experiment No. 525 are obtained for Experiment Nos. 529, 530, 531, 535, 536, 537, 541, 542, etc. in Table 13, and the effect of suppressing the fluctuation of the surface level is not good. ing.

  The effects of the inner diameter ratio (D0 / D1) are summarized in Table 14, Table 15, and Table 16. Specifically, Table 14, Table 15, and Table 16 show the experimental numbers 3, 9, 15, 28, 35, 42, 49, 55, 62, 69, in which the effect of suppressing the variation of the surface level of the upper part of the mold is not sufficient. In FIG. 10, the inner diameter ratio is changed by changing the inner diameter D0 of the injection tube 2 to 100 mm, 120 mm, 128 mm, 132 mm, 140 mm, 160 mm, and 180 mm.

The experimental numbers 544 in Table 14 are the same as the experimental numbers 3 except for the inner diameter D0 of the injection pipe, and thus the formulas (1) to (3) are satisfied.
Furthermore, when the inside diameter ratio is calculated, since the inside diameter D0 of the injection pipe 2 is 128.0 mm and the inside diameter D1 of the horizontal runner is 56.0 mm, the inside diameter ratio is 128/56 = 2.29, and the lower limit of Expression (4) is 1.80. It becomes above. That is, the experiment number 544 satisfies the equation (4).

Therefore, with regard to Experiment No. 544, the movement of the bubbles of argon gas to the mold side can be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface becomes good. That is, a sufficient effect of suppressing the fluctuation of the molten metal surface is obtained.
Similar results to this experiment No. 544 are also obtained for experiment Nos. 543, 545, 546, 549, 550, 551, 552, 555, 556, 557, 561, 562, 563, 564, 565, etc. in Table 14. And the effect of suppressing the fluctuation of the surface is good.

On the other hand, as for Experiment No. 547, Equations (1) to (3) are satisfied as in Experiment No. 3.
However, when the inside diameter ratio is calculated, since the inside diameter D0 of the injection pipe 2 is 160.0 mm and the inside diameter D1 of the horizontal runner is 56.0 mm, the inside diameter ratio is 160/56 = 2.86, which is the upper limit of 2.50 in equation (4). Over. That is, the experiment number 547 does not satisfy the equation (4).

In addition, about experiment number 547, it can suppress reliably that the bubble of argon gas moves to the casting_mold | template side, and the control effect of a hot water surface fluctuation becomes favorable. However, since the inner diameter D0 of the injection pipe 2 is larger than necessary and the manufacturing cost is increased, the overall result is rejected.
The same result as this experiment No. 547 is obtained also for the experiment Nos. 548, 553, 554, 559, 560, 566 etc. in Table 14, and although the effect of suppressing the fluctuation of the surface level is good, the manufacturing cost is not good. It has become a thing.

The experiment No. 570 in Table 15 is the same as the experiment No. 35, and thus the formulas (1) to (3) are satisfied.
Furthermore, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 140.0 mm and the inner diameter D1 of the horizontal runner is 64.0 mm, the inner diameter ratio is 140/64 = 2.19, which is the lower limit of 1.80 of equation (4). It becomes above. That is, the experiment number 570 satisfies the equation (4).

Therefore, with regard to Experiment No. 570, the movement of bubbles of argon gas to the mold side can be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface becomes good. That is, a sufficient effect of suppressing the fluctuation of the molten metal surface is obtained.
The same results as in this experiment No. 570 are as in Experiment No. 567, 568, 569, 571, 573, 574, 575, 576, 577, 579, 580, 581, 582, 583, 587, 588, 589, 590 in Table 15. And the like, and the effect of suppressing the fluctuation of the surface level is good.

On the other hand, as for Experiment No. 572, Formulas (1) to (3) are satisfied as in Experiment No. 35.
However, when the inside diameter ratio is calculated, since the inside diameter D0 of the injection pipe 2 is 180.0 mm and the inside diameter D1 of the horizontal runner is 64.0 mm, the inside diameter ratio is 180/64 = 2.81, which is the upper limit of 2.50 in equation (4). Over. That is, the experiment number 572 does not satisfy the equation (4).

In the case of Experiment No. 572, movement of bubbles of argon gas to the mold side can be surely suppressed, and the effect of suppressing the fluctuation of the surface of the molten metal becomes good. However, since the inner diameter D0 of the injection pipe 2 is larger than necessary and the manufacturing cost is increased, the overall result is rejected.
The same results as those of Experiment No. 572 are also obtained for Experiment Nos. 578 and 584 in Table 15, and the like, and although the effect of suppressing the fluctuation of the surface level is good, the manufacturing cost is not good.

Furthermore, as for Experiment No. 585, Formulas (1) to (3) are satisfied as in Experiment No. 55.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 120.0 mm and the inner diameter D1 of the horizontal runner is 72.0 mm, the inner diameter ratio is 120/72 = 1.67, and the lower limit of Expression (4) is 1.80. Less than. That is, the experiment number 585 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as those of Experiment No. 585 are also obtained for Experiment Nos. 55, 586, 62, 591, 592, 69, 597, 598, 99, 603, 604, etc. Results are inadequate.

Since the experiment number 593 in Table 16 is the same as the experiment number 62, the equations (1) to (3) are satisfied.
Furthermore, when the inside diameter ratio is calculated, since the inside diameter D0 of the injection pipe 2 is 132.0 mm and the inside diameter D1 of the horizontal runner is 72.0 mm, the inside diameter ratio is 132/72 = 1.83, which is the lower limit of 1.80 of equation (4). It becomes above. That is, the experiment number 593 satisfies the equation (4).

Therefore, with regard to Experiment No. 593, the movement of the bubbles of argon gas to the mold side can be reliably suppressed, and the effect of suppressing the fluctuation of the molten metal surface becomes good. That is, a sufficient effect of suppressing the fluctuation of the molten metal surface is obtained.
The same results as those of Experiment No. 593 are obtained also for Experiment Nos. 594, 595, 596, 599, 600, 601, 602, 607, 608, etc. of Table 16, and the effect of suppressing the fluctuation of the surface level is good. It has become.

On the other hand, as for Experiment No. 592, Formulas (1) to (3) are satisfied as in Experiment No. 62.
However, when the inner diameter ratio is calculated, since the inner diameter D0 of the injection pipe 2 is 128.0 mm and the inner diameter D1 of the horizontal runner is 72.0 mm, the inner diameter ratio is 128/72 = 1.78. Less than. That is, the experiment number 592 does not satisfy the equation (4).

Therefore, although the hot water level fluctuation is suppressed to a certain extent by the effect of the swirling flow, the movement of the argon gas to the mold is not reliably suppressed, and the effect of suppressing the hot water level fluctuation is not sufficient. It has become.
The same results as those of Experiment No. 592 are obtained for Experiment Nos. 62, 591, 69, 597, 598, 93, 603, 604, 605, 606, etc. in Table 16, and the effect of suppressing the water level fluctuation is not obtained. It is a satisfactory result.

Since the water level fluctuation at the upper part of the mold is affected by whether the argon gas bubbles taken in from the injection pipe move into the mold, the length L1 of the vertical straight part 5b of the injection port and the enlarged diameter part 5a The length L2 does not affect the surface level fluctuation at the top of the mold.
That is, according to Tables 2 to 16, if Formulas (1) to (4) defined in the present invention are satisfied, the length L1 of the vertical portion 5b and the diameter-increased portion 5a There is no effect of changing the length L2.

  In summary, according to the sub-casting method of the present invention, when the molten steel 7 flowing through the horizontal runner 4 is injected into the mold 6 from the injection port 5 provided at the bottom of the mold 6, the injection port 5 The flow rate W of the molten steel 7 injected into the mold 6 from one of them is defined as 1.5 to 3.0 t / min, and the inner diameter D2 of the injection port 5 is at least (6.437 × W + 0.741 × D1−10.849), horizontal The diameter of the runner 4 is less than or equal to D1, and the center of the inlet 5 is shifted from the center of the horizontal runner 4 to be within (0.08 × D1) or more and (0.5 × D1) or less. When the taper angle θ of 5a is in the range of 2 ° ≦ θ ≦ 8 ° and the inner diameter of the horizontal runner 4 is D1, the inner diameter D0 of the injection pipe 2 is 1.8 × D1 ≦ D0 ≦ 2.5 × D1. It is about keeping it as it is.

  According to the present invention, the injection is performed by setting the inner diameter D2 of the inlet 5 to at least the inner diameter D1 of the horizontal runner 4 and shifting the center of the inner diameter D1 of the horizontal runner 4 and the center of the inner diameter D2 of the inlet 5 It is possible to impart a swirling flow to the flow, that is, to promote the generation of vortices, and the injected flow is injected along the enlarged diameter portion 5a having a prescribed taper angle θ, thereby making the molten steel As well as preventing the inclusion of the in-mold agent 8 added to the initial stage of the injection 7 into the molten steel 7, it is possible to reduce inclusion defects and produce high quality steel.

Further, by providing the enlarged diameter portion 5a having a prescribed taper angle in the injection port 5, the injection flow can be diffused into the mold 6 without using a special refractory.
In addition, when the molten metal is injected from the ladle into the injection pipe 2, it is possible to suppress the argon gas entering the molten metal from moving into the mold through the horizontal runner, and the bubbles of argon gas are on the surface of the molten metal It is possible to reliably suppress the disturbance of the surface of the molten metal at the time of rupture, and to produce a high quality steel in which inclusion agents are not involved in the entire range from the bottom of the mold to the upper part and inclusion defects are reduced.

It should be understood that the embodiments disclosed herein are illustrative and non-restrictive in every respect.
In particular, in the embodiment disclosed this time, matters not explicitly disclosed, such as operating conditions and conditions, various parameters, dimensions of components, weights, volumes, etc., deviate from the range normally practiced by those skilled in the art. It is not necessary for the person skilled in the art to use values that can easily be assumed.

1 Sub-casting ingot machine
2 Injection pipe 2a Funnel part 2b Piping before injecting water into the funnel part 3 runner 4 horizontal runner 5 inlet (improvement nozzle, vertical runner)
5a Expanded diameter portion 5b Vertical portion 6 Mold (container)
7 Molten steel (water)
8 internals 9 ladle 10 ultrasonic displacement sensor 11 ultrasonic displacement sensor 11a sensor head 11b amplifier unit 12 data logger 20 conventional nozzle inlet

Claims (1)

When pouring and processing molten steel through a runner from the injection port provided at the mold bottom to the mold whose inner diameter is 1000 mm to 2000 mm, the casting and forming of the bottom of the molten steel is performed.
The runner has a horizontal runner facing in the horizontal direction in the mold bottom, and an inlet communicating with the horizontal runner and facing in the vertical direction, and injecting the molten steel into the mold.
The injection port has a tapered enlarged diameter portion which is expanded upward, at an end on the mold side of the runner.
The injection is performed so that the injection flow rate W of molten steel per injection port is 1.5 to 3.0 t / min,
The relationship between the inner diameter D1 [mm] of the horizontal runner and the inner diameter D2 [mm] of the inlet at the lower end side of the enlarged diameter portion satisfies the range indicated by the equation (1),
6. 437 × W + 0.741 × D1-10.849 ≦ D2 ≦ D1 (1)
However, W: Injection flow rate of molten steel per mold [t / min]
The amount of deviation d between the center of the inner diameter D2 and the center of the inner diameter D1 satisfies the range indicated by the equation (2),
0.08 × D1 ≦ d ≦ 0.5 × D1 (2)
The taper angle θ of the diameter-increasing portion with respect to the vertical direction satisfies the range shown by equation (3)
2 ° ≦ θ ≦ 8 ° (3)
Assuming that the inner diameter of the injection pipe for supplying molten steel from the ladle to the horizontal runner is D0 [mm], the equation (4) is provided between the inner diameter D0 of the injection pipe and the inner diameter D1 of the horizontal runner. The relationship shown by is established
1.8 × D1 ≦ D0 ≦ 2.5 × D1 (4)
Down-casting method characterized in that.