JPS6072645A - Apparatus for producing hollow billet - Google Patents

Abstract

PURPOSE:To prevent the inside surface crack and other defects of a hollow billet and to stabilize and smooth casting by attaching a graphitic body via a refractory heat insulating or heat holding material to the cast surface of a water- cooled casting mold for a core. CONSTITUTION:A core is concentrically attached by means of a support 5 to the center of a metallic casting mold 1 of a water cooling type which is opened at the top and bottom. This core is formed by attaching a graphitic cast surface body 3 via a refractory heat insulating or heat holding material 4 to the upper part of a water cooled metallic core 2 and extending the bottom of the core 2 under said body. The cooling water supplied into the core through a pipe 6 is discharged 10 toward the inside surface of a billet 12 and cools the billet 12 together with the cooling water 10 of the mold 1. The solidification start point is therefore positioned to a substantially high point on the outside of the billet 12 while the solidification start point 9 is positioned below the inside surface of the billet 12, by which the tensile stress in the central part of the wall thickness of the hollow billet 12 is relieved and the billet 12 free from internal surface crack and other defects is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hollow billet manufacturing apparatus, which eliminates cracks and other defects in the equipment for completely continuous casting of hollow billets, and effectively eliminates metal leakage. The aim is to ensure smooth operation of the plant.

When continuously casting hollow billet gold in a metal bath, such as aluminum, a metal water-cooled core is placed entirely within the outer casting enamel, and a continuous V is cast from the bottom of the water-cooled core.
It is common practice to apply cooling water to the inner surface of the hollow billet that is drawn out after CQ construction, but with this method, hot side n tends to occur in the casting process. Therefore, it is known that the yield is low. In other words, with the method described above, an L is formed from the inner and outer peripheries of the hollow billet at the same time, and the middle part of the wall solidifies later, and the shrinkage at the middle part of the wall during solidification occurs first. The valley shells on the inner and outer periphery sides that are formed by the grooves are constrained, and a force acts on the early middle part of the wall, and this tensile stress is applied to the middle part of the wall thickness. The temperature is increased by exceeding the hot rolling temperature.
Such a pattern f1. will normally propagate to the inner shell. Therefore, it has been proposed to use graphite in the core and not to cool it from the inner periphery.In other words, since the inner shell does not form, the constraint by the inner periphery shell is removed, making it difficult to generate 90%. be. However, the results of a detailed study of methods that do not cool internally in this way have shown that the wall thickness of the hollow billet is approximately 60 rpm (for example, 1 liter of metal will be generated if it exceeds 60 rpm). In other words, it was confirmed that metal 19 occurred frequently at the start of casting, making it impossible to achieve smooth casting. Molten metal is supplied and cooled from the @ mold, lower mold, and core to form a shell in the parts that contact these parts, and then the lower mold is lowered and when casting starts, the shell in contact with the core is generally the lower part. It will separate from the core formed by taking the taper so that it is slightly thinner, but when it separates from the core of such an inner peripheral shell, the molten metal in the upper part of the shell will flow into the gap created by the separation, or Otherwise, a part of the thin inner peripheral shell would melt again and cause the bath water to flow out, causing metal leakage, and in any case, stable continuous casting would not be possible. Become.

The present invention was devised after repeated studies in view of the above-mentioned circumstances, and a core is provided in the center of a mold with open upper and lower sides concentrically with the mold. The lower die is lowered while supplying the molten metal into the space formed by the core to continuously cast the cooled and solidified hollow billet, wherein the gear shift in the core at least when the core is in the fixed position. The entire surface is made of a graphite member, and a water-cooled mold is continuously formed below such a graphite member, and a heat insulating material is provided between the water-cooled mold and the graphite member. We propose an apparatus for producing billets with a core formed by inserting them into the core.

That is, to explain the specific embodiment of the present invention shown in the attached drawings, the one shown in FIG. The entire core is attached to the top of the water-cooled metal core 2, with a graphite cast surface body 3 attached to the top of the water-cooled metal core 2 via a fireproof or heat-insulating material 4, and below that, the water-cooled metal core 2 is attached. Only the bottom part of the frame extends. Cooling water is supplied to the core 2 by a cooling water supply vibro, and a hollow billet 1 is drawn out from a nozzle formed at the bottom of the core 2.
Cooling water 10 is discharged onto the inner surface of the mold 1, cooling the billet 12 together with the cooling water 10 from the bottom nozzle in the mold 1, and thus the metal supplied to the space between the mold 1 and the core 2 as described above. In the bath water 7, solidification start points 9, 9a are formed at the positions shown in the figure, that is, on the inner surface of the billet 120, the start points 9 are located considerably below the graphite body 3.
is at position 1-, whereas on the outer surface of billet 12, which is exposed to all the light from the water cooling effect in mold 1, solidification starts at point 9a.
will take a sufficiently high position.

Note that the casting in the graphite member 3 is formed into an appropriate tapered shape so that the billet 12 can be punched out easily.

In addition, as shown in the figure, in order to obtain a through-cut for attachment to the core 2, a stepped portion 2a is formed on the core 2, and the lower end of the graphite body 3 is slightly fitted together with the fireproof insulating material 4 to lock it. You can also.

Another embodiment of the present invention is shown in FIG. 2, in which a discharge hole 11 is formed in the center of the bottom of the water-cooled metal core 2 to discharge cooling water. The bottom nozzle in the one shown is replaced. In some cases, as shown in Fig. 3.4, the VC1 water-cooled metal core 2 may be short and flat, and 3 graphite cast surface bodies may be set on top of the VC1, as shown in Figure 3.4.
As shown in the diagram, it is necessary to install all the i-insurance systems. Furthermore, it is more effective to apply -C as a lubricant to the graphite member 3 as described above, such as molybdenum disulfide powder, boron nitride powder, or carbon black graphite powder. Effective adhesion can be obtained by kneading the mixture with wax, rapeseed oil, etc. and applying it.

That is, when using the apparatus of the present invention as described above, since the inner surface of the hollow billet is cast by the graphite cast surface body 3 through which the fireproof insulation or heat insulating material 4 is entirely interposed, the inner surface of the hollow billet is equivalent to or equal to the thick middle part where solidification is slow. The inner surface of the billet solidifies later than that, and the restraining force by the inner shell decreases, so the tensile stress associated with solidification shrinkage in the middle part of the wall thickness is relaxed ε-
A preferable hollow billet can be obtained in which no cracks occur in the intermediate wall thickness portion, and therefore no internal cracks occur. Moreover, if a gap is created between the graphite part 3 forming the casting surface and the inner peripheral shell formed when the part 3 is still in a cold state, such as when starting fishing fishing, Also, in the early stage of metal discharging, the metal that is about to leak is quickly subjected to the quenching effect by the water-cooled mold part below it, and therefore, the gap between the metal and the inner peripheral shell is properly closed in the state of oozing metal. Therefore, at least the leaked metal will not flow downward from the core water-cooled mold part.

To explain a specific example of operation using the device V of the present invention as described above, in the central part of an aluminum water-cooled chest mold 1 with an inner diameter of 285 MΩ and a depth of 70 wLl, there is an upper end with an outer diameter of 125 m + nZ reaching the lower part. A graphite cast surface body 3 with a 9° taper and a depth of about 60 mm and a depth of about 4 to 5 mm is attached via a fireproof insulation material 4 made of glass cloth felt. The water-cooled aluminum water-cooled core 2 of 102wnL3 is exposed to a depth of 2oIIIm below the graphite cast surface body 3, and in this core 2, as shown in Fig. ('ft p' water is discharged onto the inner surface of the hollow metal billet 12, and cooling water is simply discharged from the bottom of the core 2 as shown in Fig. 2, and the discharged cooled water is supplied to the inner surface of the billet 12. t'LA5 for each thing that has been prevented from being
056 alloy (AA-5% Mg) was continuously cast.

The casting temperature was 700°C and the casting speed was 90mm/
min, and the amount of cooling water supplied from the water-cooled mold 1 to the outer surface of the billet 12 is 50 t/min/n o u
td, but even in the case of ih]f'L, it was possible to stably obtain a hollow billet of approximately 85 mm in thickness with no cracks on the inner surface and a very smooth thickness.

In addition, as a comparative example of the present invention, only a graphite core with an outer diameter of 125 mm at the upper end, a die-cut bar with a downward angle of 9 degrees, a depth of 100 mm, and a thickness of about 5 bars was used. In the case where the mold was installed in the water-cooled casting m1, metal leakage from between the mold and the core was investigated immediately after the start of casting, and various tests were conducted to prevent metal leakage, but casting was not possible.

According to the present invention as described above, a core is provided in the center of a water-cooled mold that is open at the top and bottom, concentrically with the mold,
While supplying molten metal into the space formed between the seven-year-old mold and the core, the lower mold is lowered completely, and the
In the case where the hollow billet cooled and solidified between the A type and the core is completely continuously cast, the entire cast surface of the core at least during steady casting is made of graphite through a refractory insulation or heat insulating material. Since the hollow billet is formed from a single piece, during the above-described continuous casting, the inner surface of the hollow billet forms a shell simultaneously with or after the middle lb-thick wall part of the hollow billet. Therefore, it is possible to obtain a good hollow billet with no cracks or other defects on the inner surface, and a water-cooled mold is placed below the graphite body as described above. Since it was made of cedar BSR in the early stages of rust formation, a part of the shell formed on the cast surface of the graphite part, and the shell solidified and shrunk, or when the hollow billet was pulled out and separated from the cast surface, the shell formed. Even if a gap occurs between the shell and the cast surface, the heat from the bath water regenerates, and part of the shell melts again, causing the molten metal to leak, the quenching effect of the water-cooled mold prevents the molten metal from leaking accurately at the initial stage of leakage. It can solidify and completely prevent outflow, and therefore enables stable and smooth casting even at the start of casting, and these factors together make it possible to solidify and completely prevent outflow. This invention is industrially very effective because it allows for good and stable casting even if there is a problem.

[Brief explanation of drawings]

The drawings show embodiments of the present invention, and FIG. 1 is a sectional view showing one example of the device according to the invention, and FIG. 2 is a sectional view showing another example thereof. ,1
2 is the water-cooled mold, 2 is the water-cooled mold for the core, 28 is the stepped part, 3
4 is a graphite cast surface body, 4 is a refractory material [heat material, 5 is a support, 6 is a cooling water supply pipe, 7 is a molten metal, 9 and 9a are solidification start points, 10 is a cooling water, and 12 is a hollow billet. It shows. Patent Applicant Nippon Light Metal Co., Ltd. Inventor Name Oro 1) Renma Masaru Sugiyama Maki 1 Ichigo Sakae Yoshitodo Ichi Kawa Masazo Agent Patent Attorney Usugawa −zu゛”′−= −Goko / Enji 2Z Prison ♂ Enjian 4 Country

Claims (1)

[Claims] A core is placed concentrically with the mold in the center of the mold, which is open at the top and bottom, and the lower mold is fully lowered while supplying molten metal into the space formed between the mold and the core. The hollow billet gold that has been cooled and solidified between the mold and the core is continuously cast on the lower mold, and the casting surface of the core at least during steady casting is covered with a graphite member. and a water-cooled mold is provided below the graphite member, and a core is formed by interposing a fireproof insulation or heat insulating material between the water-cooled mold and the graphite member. hollow billet manufacturing equipment.