JPH0767598B2 - Semi-continuous casting method for branched ingots - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION “Object of the Invention” The present invention relates to a semi-continuous casting method of hot-top casting of a branched cross-section ingot, and in semi-continuous casting of the branched cross-section ingot, cracking or the like occurs in the ingot. It is intended to provide a method capable of accurately casting a superior ingot having a branched cross-section, which is appropriately prevented.

(Industrial field of application) Casting technology for Y-shaped, V-shaped, T-shaped, etc. branched cross-section ingots.

(Prior Art) Castings and forged products are used for aircraft, vehicles, industrial machines, precision instruments, and the like. Cast products have inferior toughness compared to forged products, and it is difficult to keep up with recent weight reductions. On the other hand, forged products have high toughness and can be made even lighter, but if the product shape is complicated, it requires multiple steps for forging and the product yield is poor, and the billet obtained by continuous casting is close to the product. It has been attempted to forge an extruded material obtained by extrusion molding into a final product into a final product, but an extrusion step is required and both methods are costly.

For this reason, in recent years, a method has been proposed in which a forging material having a shape close to that of a product is semi-continuously cast and cut into a required length is used. For example, Japanese Patent Laid-Open No. 2-179336
In the gazette, when a metal material having a cross section of a plurality of arm shapes is cast by a continuous casting method, if there is a bent portion in the arm shape, the bent portion of the arm shape hugs the mold smoothly due to thermal contraction during cooling. Since continuous casting cannot be performed, when performing level pore casting of the metal material having the above-mentioned arm shape by the hot top casting method, a rough-shaped material having a plurality of arm shapes extending in a radial line without a bent portion is cast, and then at least one piece is cast. It is disclosed that the radial arm is bent and then forged into a predetermined shape.

Note that hot-top casting is a method in which a heat insulating header is provided on the upper part of the water-cooled mold and the molten metal is supplied to this part and the pedestal of the ingot is lowered, and casting is performed while applying cooling water to the ingot.
According to this method, the depth of the water-cooled mold can be made shallow and the supplied molten metal can be rapidly solidified, so that the mechanical properties of the product are stable, and it is also adopted in the above-mentioned JP-A-2-179336. is there.

In the hot-top casting method, there is a method of using a float as a method of supplying the molten metal into the above-described heat insulating header. However, if the float is small, the molten metal surface and the supply amount are not stable and the ingot of any cross-sectional shape is formed. It is not suitable for casting and is not general in the shape of the ingot. For this reason, a method is disclosed in which the level of molten metal is supplied from the side of the heat insulating header as disclosed in Japanese Patent Laid-Open No. 2-179336.

(Problems to be Solved by the Invention) However, in the case of the conventional method as described above, cracks occur at the base portion of the branched extension and cold shut occurs at the tip of the extension, and in any case, It is impossible to accurately cast a superior ingot having a branched cross section.

"Structure of the Invention" (Means for Solving the Problems) The present invention was devised through repeated studies to solve the problems in the conventional devices as described above, and is as follows.

When semi-continuously casting a ingot having a cross-section having a plurality of extending portions by a hot-top casting method, the molten metal is placed at a position corresponding to the base between the extending portions in the mold at substantially the same level as the molten metal surface in the mold. A semi-continuous casting method of a branched cross-section ingot, characterized in that the molten metal is introduced and is distributed and supplied to the introduced molten metal by urging a flow direction force toward the extending direction of the extending portion.

(Examples) Explaining specific embodiments of the present invention as described above, the inventors of the present invention applied, for example, as a method for mass-producing the undercarriage member of an automobile as described above according to the cross section of those members. We have repeatedly studied the direct semi-continuous casting of cross-section members. That is, typically, a semi-continuous casting of an ingot having a Y-shaped cross section by a casting equipment as shown in FIG. 4, a hot top portion 2 is provided for a mold 1, and a molten metal is injected by a gutter 3, The ingot 6 in which the solidified shell 4 is formed in the mold 1 is received by the ingot receiving stand 7 and drawn out, and cooling water 8 is poured from the mold 1 to the outer surface of the ingot 6 for rapid cooling. However, when such semi-continuous casting was carried out, as shown in FIG. 5, it was inevitable that cracks 17 were formed along the casting direction at the base 18 of each extending portion 16 in the ingot 6. Therefore, in order to prevent such cracking, if the casting is performed at a low speed or the molten metal temperature is set to a low temperature, the casting surface at the tip of the extended portion becomes cold shut, and the ingot structure may not be preferable. I was known.

Then, as a result of further experimental research on the cause of such cracks, it was found that the positions of the cracks were large where the flow of the molten metal supplied from the end of the mold hits the mold on the opposite side, particularly in the boundary of the molten metal. Further, when the structure of the cross section of the ingot in which cracking occurred was observed, the location of cracking was such that the thickness of the coarse cell layer was thinner and the floating crystals were smaller than at the tip of the extending portion. From these facts, the present inventors presumed that cracking occurs because the temperature of the solidified shell in the mold portion in contact with the flow of the hot molten metal becomes weak and cannot withstand the solidification shrinkage force in the ingot. However, in order to prevent the cracks as described above, the inventors conducted a number of experiments and examined the ingot, and introduced the molten metal to be the ingot into the extension base, and in the extension direction of the extension. It was discovered that the above cracks can be prevented by supplying it toward the surface.

When casting by the above method, cracking does not occur at the base of the extension part because the temperature of the melt at the extension part and the base part of the extension part are the same or the tip of the extension part becomes slightly higher, and the hot melt Flow does not directly hit the mold at the base of the extension part, the solidified shell at the base of the extension part is stronger and more uniform than the solidified shell at the extension part to prevent cracking and the molten metal at the tip of the extension part It seems that the casting surface at the tip of the extension does not become cold shut due to the higher temperature. Further, in this way, the squeeze of the ingot is reduced in continuous casting, and smooth continuous casting can be realized.

Example 1 One of the casting apparatuses for carrying out the present invention based on the above-described examination results is as shown in FIG. 1, and casts a V-shaped ingot having a cross section having two extending portions. As a casting apparatus, a plan view of FIG. 1A and an AA ′ in FIG.
The mold 1 is constructed as shown in a vertical cross section through the mold 1 and is forcibly cooled by cooling water, the hot top part 2 made of a fireproof heat insulating material on the upper part of the mold 1 and the mold 1 on the hot top 2a. A molten metal distributor 9 is provided to rectify and supply the molten metal to the extending direction of each extending portion, and an ingot pedestal 7 connected to an elevating device below the mold 1. The molten metal is introduced from the pouring port 10 provided on the hot top at almost the same level as the gutter surface, and is rectified in the extending direction of the extending portion by the molten metal straightening plate 11 and the hot top, and is supplied in a substantially horizontal direction. ,
The molten metal is prevented from directly hitting the base portion of the ingot extending portion of the mold 1.

For casting, first, the ingot pedestal 7 is raised to match a predetermined position in the mold, and then the molten metal is filled from the pouring port 10 through the molten metal distributor 9 to fill the inside of the mold. After being heated by the mold 1 and the ingot pedestal 7 to form a solidified shell, the elevating device is continuously lowered to start casting. The solidified shell 4 generated by the heat removal in the mold 1 is more effectively removed by the cooling water 8 to form a long solidified ingot 6.

Using the casting equipment as described above, JI shown in Table 1 below.
Casting of S6061 alloy was performed. The same JIS 60 as a comparative example
The 61 alloy was cast by removing the molten metal straightening plate 11 as described above.

The casting results as described above are summarized in Table 2 below.

Example 2 As another specific example of the present invention, the casting apparatus used by the present inventors is as shown in FIG. 2, which has three Y-shaped extending portions. FIG. 1A is a plan view and FIG. 1B is a vertical cross-sectional view taken along the line AA ′ of the casting apparatus for casting an ingot having a cross section, which is forcibly cooled by cooling water. A mold 1 and a hot top 2 made of a refractory heat insulating material on the upper part of the mold 1 and a molten metal distributor 9 which rectifies and supplies the molten metal supplied to the mold in the extending direction of each extending portion with a rectifying plate 11. And having an ingot pedestal 7 connected to the lifting device at the bottom is the same as in FIG. The molten metal is introduced from the pouring port 10 provided in the hot top 2 at almost the same level as the level of the gutter, and is rectified by the molten metal rectifying plate 11 placed on the distributor 9 at the base of the extension part, and is almost spread out. It is the same as in the case of FIG. 1 that the molten metal is supplied in the horizontal direction toward the extending direction of the outlet so that the molten metal does not directly impinge on the base corresponding portion of the ingot extending of the mold 1. is there.

Regarding casting, first, the ingot cradle 7 is raised to a predetermined position in the mold 1, the molten metal is poured, and the molten metal is distributed through the molten metal distributor 9 to fill the inside of the mold 1. 1 and the ingot cradle 7 are deheated to form a solidified shell, and then the elevating device is continuously lowered to start continuous casting.
The solidified shell 4 generated by being deheated in the mold is more effectively deheated by the cooling water 8 from the mold 1, and a long solidified ingot 6 is obtained.
It is also the same as in the case of FIG.

However, the JIS6061 alloy prepared separately for casting by the apparatus shown in FIG. 2 as described above is as shown in Table 3 below. For comparison, in the apparatus shown in FIG.
Similarly, the apparatus shown in FIG. 4 from which the straightening vane 11 was removed was also continuously cast.

Thus, the JI according to the present invention example and the comparative example as described above
Table 4 below summarizes the casting conditions and the results of the S6061 alloy.

That is, none of the ones produced by the method of the present invention were cracked, and smooth continuous casting was possible to obtain each casting having a smooth casting surface, whereas cracks were generated in the comparative example, Casting was not obtained smoothly, the casting surface was not favorable, and cold shut occurred.

In addition to the above-mentioned ones of Examples 1 and 2, the inventors of the present invention also carried out the same with a continuous casting apparatus for obtaining a slab having a T-shaped cross section as shown in FIG. Also in this case, since the extending portions on both sides are only right-angled with respect to the Y-shaped one as shown in FIG. 2, it is possible to perform continuous casting smoothly just as in the case of the second embodiment. It was possible and there was no cracking.

"Effects of the Invention" According to the present invention as described above, a branched cross-section ingot having a complicated cross-sectional structure is smoothly cast as a deformed ingot, the crystal grains in the ingot are made uniform, and the distribution of floating crystals is made uniform. Since it is possible to provide a cast material that is suitable as a melting member for various machinery and equipment, and is capable of appropriately obtaining a cast body that does not cause cracking and also has a good casting surface, and that is industrially effective. It is a great invention.

[Brief description of drawings]

The drawings show the technical contents of the present invention, and FIGS. 1 to 3 are respectively a plan view of a casting apparatus for carrying out the method of the present invention and a vertical sectional view taken along a cutting line in the plan view. FIG. 4 is a plan view and a vertical sectional view of a casting apparatus according to the conventional method, and FIG. 5 is an end view of a cast body according to the conventional method. However, in these drawings, 1 is a mold, 2 is a hot top part, 3 is a gutter, 4 is a solidified shell, 5 is a solidification interface, 6 is an ingot, 7 is an ingot pedestal, 8 is cooling water, and 9 is molten metal. A distributor, 10 is a pouring port, and 11 is a current plate.

Claims (1)

[Claims] 1. When semi-continuously casting an ingot having a plurality of extending portions in a cross section by a hot top casting method, the molten metal is at a level approximately the same as the molten metal surface in the mold, and the base portion between the extending portions in the mold. A semi-continuous casting method for a branched cross-section ingot, characterized in that the molten metal is introduced into a position corresponding to the above position and a flow direction force in the extending direction of the extending portion is applied to the introduced molten metal for distribution and supply.