JPS6033852A - Casting mold for ingot making - Google Patents

Abstract

PURPOSE:To improve the contact between a casting and water-cooled copper plates and to cast a steel ingot having no internal defects in the stage of casting the steel ingot with an upward expanded casting mold consisting of long-side plates and short-side plates by attaching the water-cooled copper plates to the inside of the long-side plates and making the same movable toward the inside. CONSTITUTION:Water-cooled copper plates 10A are attached to the inside of the long- side plates 8 of a casting mold formed of the long-side plates 8 and short-side plates 12 so as to expand upward at an angle theta on the double molding boards 2B on a molding board 2A. A clearance 11 is provided between the bottom end thereof and the boards 2B and is kept closed with asbestos, etc. A molten steel 32 is cast by bottom pouring through a pouring pipe 4 and a runner 6 into the casting mold. The molten steel begins to solidify from the surface in contact with the boards 2B and the plates 10A and forms a solidified shell 34. The steel ingot shrinks on progressing of the solidification and a clearance is made between the shell 34 and the plates 10A and therefore the plates 12 are moved upward to form a spacing from the plates 8. The plates 8 are pressed by hydraulic cylinders 30 to bring the plates 10A into contact with the solidified shell at all times. The decrease in the cooling speed of the steel ingot is obviated and the steel ingot having no internal defects such as reverse V segregation, porosity, etc. is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mold for making ingots, and more particularly to an assembly mold for manufacturing steel ingots for extremely thick plates.

Conventionally, large flat steel ingots for extra-thick plates were made from ordinary cast iron atll.
Alf so-called 1 1- 6JI&y+h sweet 1'! -11L&
& i + / Shi7 11k W Although ingots were made using &, the following drawbacks could not be avoided. In other words, a gap is generated between the solidified shell and the inner wall of the mold due to thermal contraction of the solidified shell at a relatively early stage after pouring molten steel, so heat removal by the mold is suppressed and the time until solidification is completed is only extended. Instead, reverse segregation occurs inside the steel ingot, and furthermore, it is almost impossible to prevent the formation of voids, which are usually called "zaku", in the center of the steel ingot.

Conventionally, the following measures have been taken to prevent internal defects in these steel ingots. (a) Method using a wide mold 1) Attach a heat insulating material to the feeder frame at the top of the mold and supply a sufficient amount of feeder.

However, although method (a) has the effect of making the solidification profile formed by the solidification interface more concave when the center of the steel ingot solidifies, it is still far from being sufficient, and it does nothing to prevent inverted V segregation. It has the disadvantage of being ineffective.

In method (b), the solidification of the upper part of the steel ingot is delayed, so the solidification profile at the center of the steel ingot is made more concave, and ′! Although it has the effect of preventing shrinkage cavities that occur in the final stage of solidification from penetrating into the copper ingot, it is not sufficient to prevent "zaku", and
It is simply impossible to prevent segregation. Furthermore (a),
Even if the method (b) is used in conjunction with the conventional molding equipment, the effect of preventing "zaku" and inverted V segregation in the steel ingot is still insufficient.

Thus 1 Steel ingots manufactured by the conventional ingot-forming method using ordinary molds generally exhibit reverse ■ segregation when the thickness of the steel ingot exceeds 500 to 600 mm, and as the thickness of the steel ingot further increases, reverse ■ segregation occurs. The area of the band becomes wider and the roughness defects become noticeable, and the roughness is not compressed even by forging or rolling, and remains as a void defect in the finished product.

In order to prevent the above-mentioned drawbacks and to prevent or reduce reverse segregation and grain defects, an ingot forming method using an internal water-cooled copper plate pressing method has been proposed. The basic idea is to use an internal water-cooled copper plate mold, and to respond to the heat shrinkage of the steel ingot that occurs as solidification progresses, the long side of the mold surface is moved so that the mold is always in contact or pressure contact with the steel ingot. Speed up the solidification rate of steel ingots.

At the same time, combined with the effect of the upper wide mold, it is possible to make the solidification blob of the steel ingot into a more concave shape.

These proposals are very good, but [because the solidification yield of one block is different between the upper and lower parts, the long side mold surface has a structure in which the inclination angle can be changed freely, and when the inclination angle is changed, the long side side The structure must be such that the copper plate and surface plate do not rotate. In the case of large-sized steel ingots, the length of the long-side mold (one side) alone is about 10M, so it is extremely difficult to support this weight and satisfy the above conditions. However, the current situation is that the process equipment has not been developed.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide an ingot-making mold that can prevent or extremely reduce internal defects in steel ingots, particularly reverse segregation and grain defects.

The gist of the present invention is as follows.

That is, a set of long-side molds having a tapered upper part,
A water-cooled copper plate inscribed in the long-side mold with a gap from the upper surface of the surface plate, a pair of short-side molds sandwiched between the long-side mold and the water-cooled copper plate, and an upper end of the long-side mold that penetrates horizontally. a long side support shaft that supports the upper wide taper so as to be freely adjustable; a suppression device that presses the long side mold from the outside to the inside;
A guide post that guides the short side mold vertically via a support fitting, and a short side lifting device that moves the short side mold upward along the guide post. This is a mold for making ingots.

The details of the invention will be explained with reference to the illustrated embodiments.

FIG. 1 is a plan view of an embodiment of the present invention during bottom pouring and ingot making;
Figure 2 is a sectional view taken along the line ■-■ in Figure 1, and Figure 3 is ll1.
- It is a sectional view taken along the line III. The mold according to the present invention is installed on the double surface plate 2B provided on the surface plate 2A, and is cast from the injection pipe 4 via the runner 6 provided in the surface plates 2A and 2B. That's right. The long-side mold 8 and the water-cooled copper plate 10A inscribed therein are placed on the surface plate 2B at an upper wide angle θ, and a gap 11 is provided between the upper surface of the surface plate 2B and the lower end of the water-cooled copper plate 10A. The short side mold 12 is provided in a state where it is held between the long side mold 8 and the water-cooled copper plate 10A, and the short side mold 12 is supported by a support fitting 16 that can slide up and down on the guide post 14. 18, it can be raised and lowered. In this embodiment, the water-cooled copper plate 10B is also attached to the short side mold 12;
If the thickness of the steel ingot is small, the water-cooled copper plate jOB can be omitted, making the water-cooled structure unnecessary. A side plate 20 for the long-side mold 8 is erected on the surface plate 2A, and holds the long-side support shaft 24 horizontally via a bearing 22. The long side support shaft 24 passes through the upper end of the long side mold 8 and extends through the spherical bearing 26 provided on the long side support shaft 24 and the spherical bearing 28 provided on the long side mold 8. Since the side support shaft 24 supports the long side mold 8, the long side mold 8 can be freely tilted and the upper wide taper θ can be freely adjusted. Further, since the spherical seat 26 is attached to the long side support shaft 24 so as to be movable laterally, the long side mold 8 can also be moved in the axial direction. Furthermore, since the gap 11 is ensured from the beginning as described above between the lower end of the water-cooled copper plate 10A on the long side and the top surface of the surface plate 2B, interference between the water-cooled copper plate 10A and the surface plate 2B does not occur during tilting. . however.

This gap 11 must be filled with a refractory material such as asbestos during injection to prevent steel leakage during injection of molten steel. Further, a hydraulic cylinder 30 is installed on the side plate 20 as a suppressing device for pressing the long-side mold 8 from the outside to the inside.

Next, the procedure of the ingot making operation using the mold according to the present invention will be explained. From injection pipe 4 to surface plate 2A.

When the molten steel 32 is supplied to the mold according to the present invention via the runner 6 provided in the runner 2B, the molten steel 32 first solidifies from the inner wall of the mold and from the surface plate 2B side, as in the case of a normal mold. As shown schematically in FIG. 2, the solidified shell 34
is formed, and at the same time, a void is generated between the solidified shell 34 and the water-cooled copper plate 10A. This phenomenon usually occurs within 2 to 3 minutes after the molten steel injection is completed.
Happens in minutes.

Therefore, first, the hydraulic pressure of the hydraulic cylinder 30 of the long-side mold 8 holding the short-side mold 12 is slightly relaxed, and the short-side mold 12 is moved slightly upward by the short-side lifting device 18 on the short side. Thereafter, the long-side mold 8 is operated via the hydraulic cylinder 30 in a direction that reduces the gap. At this time, the long side mold 8 is suspended via the spherical seat 26, and the water-cooled copper plate 1
Since a gap 11 is secured between the lower end of 0A and the upper surface of the surface plate 2B, the long side mold 8 can freely change the inclination angle θ and press the long side surface of the steel ingot without biting the surface plate 2B. can. Even after the suppression operation of the long side mold 8 is completed, voids will still occur, so it is necessary to repeat the above operation.
The finer the pitch of this operation, the more the water-cooled copper plate 10
Contact between A and the surface of the steel ingot can be maintained continuously, and the solidification rate of the steel ingot can be increased.

Further, in some cases, by raising the short side mold 12 sufficiently and controlling the pressure of the hydraulic cylinder 30 on the long side, it is possible to maintain constant contact between the long side water-cooled steel plate 10A and the surface of the steel ingot. .

As described above, the ingot forming mold of the present invention has a large long side mold 8.
Since the upper wide taper is freely adjustable and pivots, the contact between the water-cooled copper plate 10A and the surface of the steel ingot is smooth and solidification is rapid, minimizing inverted V segregation and roughness that occurs in the center of the steel ingot. We were able to produce an excellent steel ingot with very few internal defects.

Example Molten steel having a composition as shown in Table 1 was poured into a mold according to the present invention having a shape as shown in Table 2, and the mold was 950 days thick x 2500 m wide.
A steel ingot with a weight of approximately 45 cavities and a length of 2600 mm was manufactured.

Table 1 After pouring the molten steel, during the solidification process, the hydraulic cylinder of the long-side mold was activated to press the water-cooled copper plate against the solidified steel ingot repeatedly seven times. As a result, almost no reverse segregation, which normally occurs in steel ingots, was observed, and the roughness at the center of the steel ingot was significantly reduced to a maximum of 60% compared to conventional molds.

As is clear from the above embodiments, the present invention enables the short-side mold to move upward, supports the long-side mold in a freely adjustable upper wide taper, and suppresses the mold into a solidified steel ingot. In the case of normal molds, it is possible to prevent the formation of voids between the solidified shell and the inner wall of the mold, and the solidified shell and the inner wall of the mold are in close contact with each other until solidification is complete, which accelerates the solidification rate of the steel ingot. Combined with the effect of the upper wide mold, the occurrence of reverse segregation inside the steel ingot and the occurrence of cracks in the center, which could not be avoided in the past, are prevented or minimized, making it the #1 internal defect. We were able to produce a steel ingot of extremely high quality, and we were able to fully demonstrate its excellent effects, especially in large flat copper ingots made of extremely thick plates.

[Brief explanation of the drawing]

FIG. 1 is a plan view showing the configuration of an ingot-forming mold according to the present invention.
Figure m2 is a sectional view taken along line U-II in Figure 1. FIG. 3 is a sectional view taken along the line ■--■ in FIG. 1. 2 (2A, 2B)...Surface plate, 8...Long side mold. 10 (IOA, l0BI... Water-cooled copper plate. 11... Gap, 12... Short side mold. 14... Guide post, 16... Supporting metal fittings. 18... Short side lifting device, 20. ... Side plate. 22... Bearing, 24... Long side support shaft. 26... Spherical seat, 28... Spherical bearing. 30... Hydraulic cylinder. Agent: Takeshi Nakaji, patent attorney Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) A set of long-side molds having a tapered top. A water-cooled copper plate inscribed in the long-side mold with a gap from the top surface of the surface plate, a pair of short-side molds held between the long-side mold and the water-cooled copper plate, and an upper end of the long-side mold held horizontally. a long side support shaft that penetrates through the upper wide die and is adjustable and pivotally supported by the upper wide die; a suppressor that presses the long side mold from outside to the inside; and a suppression device that guides the short side mold vertically via a support fitting. With guidebost. A mold for making an ingot, comprising: a short-side lifting device that moves the short-side mold upward along the guide post.