JPH04182046A - Semi-continuous casting method for branched cross sectional cast ingot - Google Patents

Abstract

PURPOSE:To prevent the development of a crack by introducing a molten metal to be a cast ingot into an extending base part and supplying the metal to the extending direction of an extending part. CONSTITUTION:After aligning a cast ingot receiving base 7 to the prescribed position in a mold while ascending this, the molten metal is filled up into the mold through a pouring hole 10 and further a molten metal distributor 9, and the introduced molten metal is cooled with the mold 1 and the case ingot receiving base 7, and after forming a solidified shell, a lifting device is continuously lowered to start the casting. The solidified shell 4 developed with cooling by the mold 1 is further effectively cooled with cooling water 8 to form the long solidified cast ingot 6. By this method, the cast ingot having uniform crystal grains and good surface without occurring the crack, is obtd.

Description

Detailed Description of the Invention [Object of the Invention] The present invention relates to a semi-continuous casting method for branched cross-section ingots, and appropriately prevents the occurrence of cracks in the ingot during semi-continuous casting of branched cross-section ingots. The present invention aims to provide a method that can accurately cast an ingot with an excellent branched cross section.

(Industrial application field) Casting technology for branched cross-section ingots such as Y-shape, Y-shape, and T-shape.

(Prior Art) Castings and forgings are used in aircraft, vehicles, industrial machinery, precision instruments, and the like. Cast products have inferior toughness compared to forged products, making it difficult to keep up with recent weight reduction efforts. - Dispersed forged products have high toughness and can be further reduced in weight, but if the shape of the product is complex, multiple steps are required for forging and the product yield is poor.
Attempts have also been made to extrude a billet obtained by continuous casting into a shape close to the product and forge the resulting extruded material into the final product, but both methods require an extrusion process and are expensive. Become.

For this reason, in recent years a method has been proposed in which forging materials are semi-continuously cast in a shape similar to the product and then cut into required lengths. For example, JP-A-2-179
Publication No. 336 states that when casting a metal material whose cross section has multiple arm shapes by continuous casting, if the arm shape has a bent part, the bent part of the arm shape hugs the mold due to heat shrinkage during cooling and becomes smooth. Since it is not possible to continuously cast the above-mentioned arm-shaped metal material using the hot-top casting method, a rough-shaped material having a plurality of arm shapes extending in radial lines with no bends is cast, and then at least one It is disclosed that the radial arms of the book are bent and then forged into a predetermined shape.

In Ho-notonbu casting, a heat insulating hood is installed at the top of the water-cooled mold, molten metal is supplied to this part, the ingot holder is lowered, and cooling water is poured over the ingot while casting. Since the depth of the water-cooled mold can be made shallow and the supplied molten metal can be rapidly solidified, the mechanical properties of the product are stabilized, and as mentioned above, this method is also adopted in JP-A-2-179336.

In the true top casting method, there is a method of using a float to supply the molten metal into the above-mentioned insulated header, but if the float is small, the situation and supply amount are unstable, making it difficult to cast ingots of any cross-sectional shape. The shape of the ingot is not versatile. For this reason, a method of supplying molten metal at a level from the side of a heat insulating header as disclosed in the above-mentioned Japanese Unexamined Patent Publication No. 2-179336 has been used.

(Problems to be Solved by the Invention) However, in the case of the conventional method as described above, cracks occur at the base of the branched extension, and a cold shut occurs at the tip of the extension. It is not possible to accurately cast an award-winning branched cross-section ingot.

"Structure of the Invention" (Means for Solving the Problems) The present invention has been devised after repeated studies to solve the problems of the conventional products as described above, and is as follows.

When semi-continuously casting an ingot having a plurality of extending sections in cross section, molten metal is introduced into the mold at a position corresponding to the base between the extending sections at approximately the same level as the surface of the molten metal in the mold, and at the same time A semi-continuous casting method for a branched cross-section ingot, characterized in that a flow direction force directed in the extending direction of the extending portion is distributed and supplied to the extending portion.

(Example) To explain the specific implementation S of the present invention as described above, the present inventors have developed a method for mass-producing automobile suspension members as described above, for example, based on cross-sections of those members. We have repeatedly investigated the possibility of directly obtaining a cross-sectional member by semi-continuous casting. That is, typically, an ingot with a Y-shaped cross section is semi-continuously cast using casting equipment as shown in FIG. The ingot 6 with a solidified shell 4 formed in the mold 1 is received by an ingot holder 7 and pulled out, and cooling water 8 is poured from the mold 1 onto the outer surface of the ingot 6 to rapidly cool it. However, when such semi-continuous casting is carried out, cracks along the casting direction inevitably occur at the base 18 of each extension 16 in the ingot 6, as shown in FIG. Therefore, if the casting speed is lowered or the molten metal temperature is lowered to prevent such cracks, the casting surface at the tip of the extension will become a cold shaft, and the structure of the ingot will not be favorable. I found out.

As a result of further experimental research into the causes of such cracks, it was found that cracks are most likely to occur where the flow of molten metal supplied from the end of the mold hits the mold on the opposite side, especially in the hot water area. Furthermore, when the structure of the cross section of the ingot where the crack occurred was observed, the thickness of the coarse cell layer was thinner and there were fewer floating crystals in the area where the crack occurred compared to the tip of the extension. Based on these facts, the inventors deduced that cracks occur because the temperature of the solidified shell in the part of the mold that comes into contact with the flow of hot water is so high that it becomes weak and cannot withstand the solidification shrinkage force in the ingot. However, in order to prevent the above-mentioned cracks, the inventors conducted a number of experiments and studied the ingot, and as a result, they introduced molten metal, which will become the ingot, into the base of the extension, and poured it in the direction of extension of the extension. It has been discovered that the cracking can be prevented by supplying the material in the opposite direction.

When casting using the above method, cracks will not occur at the base of the extension if the temperature of the molten metal at the base of the extension is the same or the temperature of the molten metal at the tip of the extension is slightly higher, and if the molten metal is thicker. Since the flow does not directly hit the mold at the base of the extension, the solidified shell at the base of the extension is stronger and more uniform than the solidified shell at the extension, preventing cracks and preventing the molten metal from forming at the tip of the extension. It is thought that the temperature of the casting surface at the tip of the extension part will not become cold shut due to the high temperature. Moreover, by doing so, the entrainment of the ingot during continuous casting can be reduced and smooth continuous casting can be realized.

Example 1 One of the casting apparatuses for implementing the present invention based on the above study results is as shown in FIG. 1, and casts an ingot having a V-shaped cross section with two extensions. As a casting device, the plan view of the same figure (a) and A-A in the figure (a) of the same figure
The mold is configured as shown in the vertical cross-sectional view through 1, and includes a mold 1 forcibly cooled by cooling water, a hot top part 2 made of a fireproof heat insulating material on the upper part of the mold l, and a mold located on the hot top 2a. It consists of a molten metal distributor 9 that straightens and supplies molten metal to the mold 1 in the extending direction of each extending portion, and an ingot holder 7 connected to a lifting device at the lower part of the mold 1. The molten metal is introduced from the pouring port 10 provided on the real top at almost the same level as the gutter, and the molten metal is rectified by the molten metal rectifying plate 11 and the real top part in the direction of extension of the extension part, and is then supplied in a horizontal direction. , prevent the molten metal from directly hitting the base part of the ingot extension part of the mold 1.

In casting, first the ingot holder 7 is raised and placed in a predetermined position in the mold, and then the molten metal flows from the spout 10 and further passes through the molten metal distributor 9 to fill the mold. After heat is removed 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 heat removal in the mold 1 is further effectively removed by cooling water 8, and a long solidified ingot 6 is formed.

Using the above-mentioned casting equipment, J
Casting of IS6061 alloy was carried out. As a comparative example, the same JIS6061 alloy was cast without the molten metal rectifying plate 11 as described above removed.

Table 1 The following Table 2 summarizes the casting results as described above.

Table 2 Example 2 As another specific example of the present invention, the casting device used by the present inventors is as shown in FIG. This is a casting device for casting an ingot with a cross-section of A cooled mold 1, a hot top part 2 made of a refractory heat insulating material above the mold 1, and a molten metal distribution system in which the molten metal supplied to the mold is rectified by a rectifying plate 11 in the direction of extension of each extension part. It is the same as that shown in FIG. 1 in that it has a container 9 and an ingot pedestal 7 connected to a lifting device at the bottom. The molten metal is introduced from the spout 10 provided on the real top 2 at almost the same level as the gutter, and is rectified by the molten metal rectifying plate 11 placed on the distributor 9 at the base of the extension.
As shown in Figure 1, the flow of molten metal is supplied horizontally in the direction of extension of each extension, and the flow of molten metal is prevented from directly hitting the base portion of the ingot extension of mold 1. Same as in case.

In addition, the same procedure was carried out using a continuous casting machine to obtain slabs with a T-shaped cross section as shown in Fig. 3, but in this case as well, the extensions on both sides were as shown in Fig. 2. Y
Since it was only perpendicular to the shape, continuous casting could be carried out smoothly in exactly the same way as in Example 2 described above, and no cracking occurred.

"Effects of the Invention" According to the present invention as described above, a branched cross-section ingot with a complex 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 uniform. It is possible to properly obtain cast bodies with good casting surface, no cracking, and provide efficient and low-cost casting material suitable for parts for various mechanical devices, so it is industrially effective. This is a great invention.

[Brief explanation of drawings]

The drawings show the technical contents of the present invention, and FIGS. 1 to 3 are a plan view of a casting apparatus for carrying out the method of the present invention, a longitudinal cross-sectional view taken along a cutting line in the plan view, and FIG. Figure 4 shows a plan view and a longitudinal cross-sectional view of a conventional casting device.
FIG. 5 is an end view of a conventionally cast body. In these drawings, 1 is the mold, 2 is the hot top part, 3 is the gutter, 4 is the solidified shell, 5 is the solidified interface, 6 is the ingot, 7 is the ingot pedestal, 8 is the cooling water, and 9 is the molten metal. In the distributor, 10 is a spout, and II is a current plate. Patent applicant Nippon Light Metal Co., Ltd.
Nikkei Giken Co., Ltd. Inventor Sugi 1)
Kundo Sagisaka
Sakae Yoshi-(Nar＼r11un【ゝ(DO-Q
Figure 2 (α) Figure 3 (α) 9-・Molten metal distributor ￥4 diagram

Claims (1)

[Claims] When semi-continuously casting an ingot having a plurality of extending sections in cross section, molten metal is introduced into the mold at a position corresponding to the base between the extending sections at approximately the same level as the surface of the molten metal in the mold, and at the same time A semi-continuous casting method for a branched cross-section ingot, characterized in that a flow direction force directed in the extending direction of the extending portion is distributed and supplied to the extending portion.