JPH0123656Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a casting device for hollow billets, which has a uniform structure called a shell zone and a uniform structure that does not cause perspiration, and inner and outer surfaces of the hollow billet made of aluminum or the like. The object is to provide a device that can appropriately obtain ingots.

Hollow billets for aluminum metals are extremely useful in obtaining various hollow shapes by further extrusion processing, and have been carried out in various ways in the past. However, in the conventional method for obtaining such a hollow billet, there is a rapid cooling effect from the surface of the ingot using a metal mold, a slow cooling effect due to the formation of air gaps due to contraction caused by the rapid cooling, and a further cooling effect on the ingot at the bottom of the mold. It is well known that a non-uniform structure called a shell zone occurs on the surface of an ingot (including the inner circumferential surface) due to the three-stage cooling effect of the quenching effect of direct cooling water. can be,
Also, the occurrence of sweating is inevitable. However, when the hollow billet is subjected to further extrusion processing to produce the desired product, such defects such as shell zones get caught up in the mold material, etc., and appear as streaks and surface patterns due to the difference in structure, resulting in poor strength. Otherwise, the appearance of the product inevitably deteriorates. However, multistage cooling as described above is an inevitable phenomenon in continuous casting technology using this type of water-cooled mold, and a technology for effectively solving this problem has not yet been established.

This invention was devised after repeated studies in view of the above-mentioned actual circumstances. In other words, as a result of many practical studies and speculations on obtaining an ingot without shell zones or sweating as described above, the inventors of the present invention have developed a multi-stage method for heat removal (cooling) at least in steady casting conditions. We have come to the conclusion that it is important not to do this, and that it is necessary to form a constant cooling relationship that does not change until the metal structure is completed by solidification.
Therefore, the present invention was devised to continuously cast a hollow billet in order to realize such a relationship. One of the basic embodiments of the invention is as shown in FIG. A molten metal such as aluminum is supplied to the space, and is received on a pedestal installed at the bottom of the space, thereby reducing the cooling effect of the pedestal and the water-cooled mold 1.
The molten metal is solidified on the pedestal by the cooling effect of the core 4, and the ingot 10 is pulled out from the mold 1 and the core 4 by lowering the pedestal. The cooling water 12 from the mold 1 is applied to the outer surface of the mold to achieve rapid cooling, which is similar to what has been generally known in the past. In the casting equipment, the water-cooled mold 1
A cast surface body 2 made of graphite is used in the middle or upper part of the inner surface of the mold, and a heat insulating material 3 is interposed between the graphite cast surface body 2 and the water-cooled mold 1. Similarly, for the core 4 attached with the support 5, a graphite core body 4 is used, and this graphite core body 4 is placed in the direction in which the ingot 10 is pulled out from the cast surface body 2. It is assumed that the ingot 1 has a long extension, and at least under steady operation conditions, the ingot 1
The solidification start points 8 and 9 of 0 are obtained in the graphite cast surface body 2 and the graphite core body 4 in the water-cooled mold 1, and the cooling water 1 for the ingot 10 as described above is
2, the lower part of the water-cooled mold 1 extends slightly from the cast surface body 2, and a water injection nozzle is formed in this part.

In the device shown in FIG. 1, a float 11 is positioned above the molten metal supply area formed between the water-cooled mold 1 and the core body 4 as described above, and the molten metal 6 is supplied through the float 11. Furthermore, although the molten metal 6 surface is controlled to a constant height, if the float 11 is interposed between the water-cooled mold 1 and the core 4 and the molten metal is directly supplied, the float 11
Since it is not possible to obtain a thin-walled hollow ingot 10 depending on the size of the ingot, if a thin-walled hollow ingot is to be obtained, it can be carried out as shown in FIG. That is, the core 4 is provided on a mounting body 13 made of a fireproof heat insulating material, and the hot water supply port 14 is formed in a part of the mounting body 13.
The float 11 is set in the three parts as the hot water supply area, and the other configuration is the same as that shown in FIG. A thin hollow ingot can be obtained by being received on the member 13 and then introduced between a water-cooled mold and a core.

Further, as shown in FIG. 3, a top part body 15 made of a refractory heat insulating material is provided on the water-cooled mold 1, and a setting part of the float 11 is formed in a part of the part 15.
The molding area formed between the core and the core may be supplied with hot water from the outside, and the same relationship as in the case of FIG. 2 may be formed.

Furthermore, whereas the ingots 10 shown in Figs. 1 to 3 described above are shaped and drawn out in the vertical direction, the present invention also allows the ingots 10 to be shaped and drawn out laterally. , its mode is as shown in FIG. That is, a water-cooled mold 1 in which a graphite cast surface body 2 as described above is attached to one side of a molten metal reservoir 16 with a heat insulating material 3 interposed therein, and a graphite core 4 are placed on both sides. The molten metal in the molten metal reservoir 16 is supplied from the molten metal inlet 17, and even if the molten metal is supplied, formed and drawn out sideways in this way, the structural relationship is shown in Figures 1 to 3. By making the pull-out direction similar to that shown in Fig. 3, the effects of the present invention can be obtained.

It is preferable that the cast surface of the above-mentioned cast surface body 2 has an appropriate taper, and this taper is set to 4 degrees or more, preferably about 7 to 15 degrees. A similar taper is applied to the cast surface of the core 4, but this core is preferably hollow in order to reduce its heat capacity. Furthermore, by spraying solid powder such as boron nitrite powder or carbon black on the cast surface, the surface of the ingot can be made even better, and this is especially effective when using low-density graphite. . At the start of casting, by appropriately selecting the casting temperature T, the casting speed V, and the amount of cooling water W, the solidification start point is located at a part that protrudes downward from the cast surface body 2, and the cooling water after the start is The solidification start point 8 can be moved to the cast surface body 2 by the cooling capacity, but at the time of this start, the solidification start point 8 is moved to the part of the water-cooled mold 1 that protrudes downward from the cast surface body 2.
is positioned, and after the start, the V or W can be adjusted and transferred to the graphite region of the part 2, and thereafter it can be maintained in the graphite region for casting. A preferable position of the solidification starting point 8 is about 5 mm from the end of the cast surface body 2 on the drawer side.

To explain the function of the present invention as described above, the cast surface body 2 made of graphite is blocked from the cooling effect from the water-cooled mold 1 by the heat insulating material 3, and the core 4 is made of graphite. It is clear that almost no cooling effect can be obtained because the hollow ingot billet 10 is cooled mainly by the cooling water 12.
The solidification starting points 8 and 9 are formed at a predetermined distance from the injection position of the cooling water 12, that is, the casting surface body 2
On the side, it is close to the hot water supply part, and on the side of the core 4, it is far away, and the solidification front 7 is inclined as shown in the figure. The structure in the mass 10 becomes uniform, and the occurrence of shell zones in the conventional method described above can be precisely avoided. In addition, when an ingot is formed using such a single-stage cooling capacity, and pultrusion molding is performed under lubricated conditions using the inner and outer graphite parts, sweating and other surface deterioration phenomena occur on both the inner and outer surfaces of the ingot 10. Therefore, the casting work can be carried out smoothly.

To explain a specific example of casting using the device according to the present invention, a second molding with an inner diameter of 224 mm and a depth of 80 mm is described.
At the top of an aluminum water-cooled mold 1 as shown in the figure, there is an inner diameter of 200 mm, a depth of 60 mm, and a thickness of 10 mm.
A graphite cast surface body 2 with a 9° taper on the inner surface is fixed using glass cloth felt as a heat insulating material 3, and a mounting body made of Marilite as shown in FIG. 2 is attached. 1
In a facility in which a core 4, which is a graphite ring with a depth of 50 mm and an outer diameter of approximately 144 mm and a taper of 9 degrees on the outer surface, is set concentrically, aluminum is placed in the hot water reservoir above the core.
-Supplying 5% Mg alloy molten metal via a float,
A hollow billet with an outer diameter of approximately 209 mm and an inner diameter of approximately 136 mm was cast. The lubricant used was wax mixed with carbon black.

The results of casting under the conditions of casting temperature 700℃, casting speed 120mm/min, and cooling water flow rate 90/min/mold show that the inner and outer surfaces of the hollow billet are much smoother than those made using the conventional method, and furthermore, macrostructure observation shows that It was possible to obtain a product in which no shell zone was required in either the inner or outer surface layer, and no reverse segregation layer was observed.

In addition to the above, casting was performed using the equipment shown in Figure 3. However, since the core has a small diameter, a solid core was used instead of hollow. That is, a copper hot-top mold with an inner diameter of 73 mm and a height of 30 mm has an inner diameter of 53 mm and a height of
The cast surface body 2 is made of a heat insulating material 3 made of glass cloth felt with a diameter of 20 mm and an internal taper of 9 degrees.
Fixed through, and upper outer diameter 25mm, tapered
A 9° graphite core 4 was installed concentrically, and JIS A6061 alloy was cast in this equipment using a level bore method to supply hot water, and a hollow billet with an outer diameter of 57 mm and an inner diameter of 21 mm was cast. The casting temperature is
The temperature was 680°C, the casting speed was 250 mm/min, the amount of cooling water was 50/min/mold, and the lubricant used was a mixture of boron nitride, carbon black, and wax. The inner and outer surfaces of the obtained ingot were much smoother than those produced by the conventional method, and no shell zone or reverse segregation layer was observed.

According to the present invention as explained above, it is possible to smoothly cast a hollow billet of excellent quality without a shell zone or reverse segregation layer, and with no perspiration or other surface deterioration. It is a device that can sufficiently improve the structure, strength, or surface properties of various products obtained by using the method, and is a highly effective device from an industrial perspective.

[Brief explanation of drawings]

The drawings show embodiments of the invention,
FIG. 1 is a sectional view showing one example of a device according to the invention, and FIGS. 2 to 4 are similar sectional views showing other embodiments thereof. However, in these drawings, 1 is a water-cooled mold,
2 is a graphite cast surface body, 3 is a heat insulating material, 4 is a graphite core, 6 is a molten metal, 7 is a solidification front, 8 and 9 are solidification start points, 10 is an ingot, 11 is a float, 12 is cooling water, 13 is a mounting body, 15 is a top body, and 16 is a molten metal reservoir.

Claims (1)

[Scope of utility model registration request] A concentric core is placed in a water-cooled mold that supplies hot water from one end and draws an ingot from the other end, and the water-cooled core is placed on the outer surface of the ingot drawn from between the water-cooled mold and the core. In a device that achieves rapid cooling by pouring cooling water from a mold, a graphite cast surface body is provided by interposing a heat insulating material on the inner surface of the water-cooled mold, and the core is made of graphite. In addition, the graphite core body is made to extend further in the ingot drawing direction than the above-mentioned cast face body, so that the solidification start point on the inner and outer surfaces of the ingot in a steady operating state is the same as the cast face body and the graphite core body. A hollow billet casting device characterized in that the core is located in the graphite region.