JPS5865548A - Continuous casting method - Google Patents

Abstract

PURPOSE:To prevent the sweating phenomena of ingots and to improve the quality and performance of the ingots by controlling casting conditions in such a way that the thickness of the ingots removed from molds have the nearest possible thickness of the inside dimensions of the molds. CONSTITUTION:In a continuous casting device which charges molten metal through a charging nozzle 7 into a continuous mold 5 formed by putting an endless belt 3 between a rotary wheel 1 for casting provided with a hollow groove on the circumferential surface and a rotary wheel 2 for guiding and bringing a belt 2 into moving contact with the circumferential surface in a part of the wheel 1 by means of a push roll 4, cools and solidifies the molten metal in the mold 5 by injecting water from a cooling zone 6 provided in the outside part of the mold 5, and coiling the resultant ingot 8 with a coiler 13 through hot rolling mills 12, the thickness of the ingot 8 is measured with a thickness measuring device 9, and the flow rate of the cooling water from the zone 6 is controlled by keeping the other casting conditions constant so as to control the thickness of the ingot 8 to >=98.8% the thickness of the inside dimensions of the mold 5.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a continuous casting method for continuously producing ingots by pouring molten metal into a mold formed by a rotating wheel for 1IllIIJi and an endless belt.
It is useful for improving the quality and performance of ingots by preventing the sweating phenomenon of ingots.

In general, from a mold rotating ring with a concave groove on the circumference of the gold material, and a metal endless bell that comes into contact with a part of the circumferential surface,
MU is continuously formed, molten metal is poured into the 1111M from one end, cooling water is injected around the mold to cool and solidify it, the ingot is continuously taken out from the other end of the mold, and it is heated continuously. Manufactured using inter-rolling and cold wire drawing. In this kind of casting work, fs11! The molten metal poured into the mold loses a large amount of heat due to the heat capacity of the mold itself at the initial stage, and forms solid grain (hereinafter referred to as skin) on the inner surface of the mold, and at the same time, due to the solidification and contraction of the skin, the mold A void is created at the junction, resulting in a similar shape that is smaller than the frill shape in the mold.Next, the cooling water sprayed around the mold cools it through the mold, solidifies the entire area, and becomes an ingot, which is continuous from the other end of the mold. Target #/cIiL is issued.

The voids caused by solidification shrinkage are a physical phenomenon that continues to increase while the ingot i1& in the mold decreases, and g! pJiII'i# This method reduces the heat transfer ability between the mold and the ingot, and heat extraction from the skin becomes insufficient, causing a sweating phenomenon that reduces the quality of the ingot.
The sweating phenomenon occurs when the high-temperature skin immediately after solidification re-melts locally due to internal high-temperature heat, and internal melting and low-melting-point components in the skin, i.e., unsolidified metal, melt onto the skin surface due to internal static pressure. These sweating areas are brittle and when the degree of sweating exceeds a certain limit, rolling occurs during hot rolling, significantly reducing the quality of the rolled material, and the subsequent If it causes a wire breakage accident even in the wire drawing process of
Otherwise, the product's mechanical performance may deteriorate or fluctuate, resulting in a negative impact on productivity and quality.

In order to prevent this sweating phenomenon, conventionally, casting conditions such as molten metal pouring temperature, casting speed, mold temperature f (cooling water amount), etc. are held constant during casting, but sweating occurs in the early stages of casting. The air gap is about 1/100 to 1/10 m5, and since casting is done dynamically, the condition of contact between the mold and the lump, that is, the heat extraction capacity of the mold, is constantly changing. There was a phenomenon of sweating.

In view of this, as a result of various studies, the present invention has developed a continuous casting method that prevents the sweating phenomenon. A method in which a mold is continuously formed using a belt, molten metal is poured into the mold from one end, cooling water is injected around the mold to cool and solidify the molten metal, and the ingot is taken out from the other end of the mold,
It is characterized by measuring the thickness of the taken out ingot and controlling the casting conditions so that the thickness is as close as possible to the dimensional thickness inside the mold. In other words, continuous casting under constant casting conditions. As a result of investigating the relationship between the thickness of the ingot and the number of defects caused by sweating on the surface of the ingot, it was found that the larger the thickness of the ingot, the fewer the number of defects. For example, Figure 1 shows the relationship between the ingot thickness and the number of defects caused by perspiration when continuously casting No. It can be seen that the number of defects decreases when @ Mayu ingot thickness (
tm) The casting factor that affects K is the pouring temperature (c'rc)
and the mold temperature (MTtl:), which have a relationship according to the following empirical formula.

tm(7X1G-Kano'+50X10-4MT+71.6
76) However, IT indicates the ingot temperature CC).

Based on these relationships, the present invention manufactures a healthy ingot without sweating by continuously controlling the scooping conditions for the thickness of the ingot. To set the groove, insert a metal endless belt between the fixed casting rotary wheel α) and the guide rotary wheel (2).
), and the bell l) is brought into contact with a part of the circumferential surface of the rotating ring α) by the pusher roll (4), and the # type (5) is continuously formed to cool the circumference of the chain part a (S). The molten metal is poured into the Is-type cavity from the pouring nozzle 6) K provided at one end of the casting mold (5) by spraying water around the mold (5) and cooling and solidifying it. , the ingot (8) is continuously taken out from the other end of the caster ff1 (5) and measured by the thickness measuring device 6)K.
The ingot thickness = f is measured throughout the process, and the casting conditions are controlled so that the thickness is as close as possible to the cast m (S)@IM,p thickness. In the diagram, (10) and (11) are the pinch rolls installed before and after the thickness measuring device e), (12) is the hot rolling device, and (1) is the pinch roll installed before and after the thickness measuring device e).
3) Showing the shrine and temple removal device・As for controlling the casting conditions, the pouring temperature, casting speed, and/or mold temperature (cooling water amount) are controlled by Nairinota@Pouring temperature l.
This is influenced only by the casting speed. - As the casting speed increases, the time required for the molten metal to flow from the holding furnace etc. to the pouring section becomes shorter, and during this time, the atmosphere or transfer machine etc. KIIk The amount of heat absorbed decreases and #l in the pouring part
The hot water temperature rises and the pouring temperature becomes higher. However, in normal operation, the casting speed is kept constant, so the pouring section IIt is kept at ±2 relative to the set temperature without being affected by the above.
Therefore, it is desirable to control the 1llI type temperature, that is, the amount of cooling water. Mold temperature occurs between the mold and the skin! 2! The amount of voids (thickness) changes from K, so if you reduce the amount of cooling water and raise the mold temperature, the amount of voids will decrease, the thickness of the ingot will increase, and the degree of contact between the mold and the skin will improve. A healthy skin is formed by controlling the solidification shrinkage and the sweating phenomenon is prevented. As an ingot thickness measuring device, for example, as shown in Fig. 3, the same structure as 1 (14) K! Cylinder (15) fixed at 1 itu [W? A guide roll (18) is rotatably attached to one end of a horizontally fixed shaft (17X) on the upper part of the arad (16). Even if the trajectory changes up and down, the cylinder (
15) and the shaft (17). The end of the shaft (17) opposite to the guide roll (1B) (
20), an arm (21) having the end (20) as a fulcrum;
The arm (21) is set perpendicular to the axis (17) and horizontally.
) with one end attached to the cylinder (15) (22
) It is connected with a K spring (23), and the other end of the arm (21) is pushed upward.
1) At the other end: A reference shaft (24) is fixed parallel to the shaft (17), and a guide roll (18) is fixed at one end of the reference shaft (24).
) A rotatable lower detection roll (25) is installed on the same orbit as the lower detection roll (25). Directly above the lower detection roll (25) is a reference shaft (
The upper detection roll (26) is attached to the horizontal axis (27) parallel to the upper detection roll (24).
) is rotatably mounted, and the reference axis (24) and horizontal axis (27
) A support mechanism (28) is installed between the shafts (24) and (27) to maintain vertical parallelism, and the support mechanism (28) is fixed at right angles to the reference shaft (24) by 1 mm. A differential displacement needle (29) is installed parallel to the support mechanism (28) between the reference axis (24) and the horizontal axis (27), and the upper detection roll (26) and the lower unloading roll (25), that is, a potential proportional to the change in the thickness of the # lump is generated.

According to the above-mentioned ingot thickness measuring device, as shown in FIG. Or even if a combination of these changes occurs, the guide roll (18) will always remain in one block (8).
Both upper and lower detection rolls (25) (26) (
D It is possible to accurately measure the thickness of the ingot (8) by keeping the contact point with the ingot (8) at right angles to the longitudinal direction of the ingot (2). In this case, φ) indicates an upward change, (C) indicates a downward change, and (middle indicates an upward change).

The present invention improves the quality of the ingot by controlling the casting conditions, especially the amount of cooling water, so that the thickness of the ingot taken out from the mold is 99.2% or more outside the above measurements, thereby preventing the sweating phenomenon of the ingot. , (is intended to improve productivity.

Hereinafter, the implementation of the present invention will be explained.

Using the ingot thickness measuring device shown in Fig. 3, a continuous casting experiment of HT-SS-Mg alloy was carried out using the continuous casting method shown in Fig. wX2.

Although not shown in the figure, the ingot thickness was measured by installing an ingot temperature control device in front of the pinch roll (10) to control the ingot temperature to 450±5°C. The cooling zone (6) of Mano Mold is divided into seven parts (6-
1)(6-2)...(6-7)L... The amount of cooling water in the final cooling zone (6-7) was increased or decreased. Other casting conditions are as follows, and the thickness of the ingot is 49.6-
Pouring temperature 700±2℃ Casting speed f
12.5 liters/-cooling water amount (6-1)
~(6-6) 55-hour cooling water temperature
18-25℃ In-mold thickness 50■ The thickness of the ingot taken out after a while is continuously determined by a thickness measuring device, and the ingot thickness is displayed once every 5 minutes. Displayed on the board - When the worker sees this, the Ili value is 49.
7■ Below, for example, in the case of TF49.65m, the water volume in the final cooling zone should be about 3.8m//hr or about 2.8j/hr [
◎As a result, the ingot temperature decreased from 130℃ to 145℃
The thickness of the ingot rose to 49.7cm and the ingot thickness recovered to 49.7cm. In this way, the relationship between the amount of cooling water in the final cooling zone, the thickness of the ingot, and the temperature of the ingot was investigated. The results are shown in FIG.

Next, continuous casting was carried out for a long time in the same manner based on the above casting experiment #C. As a result, the ingot thickness was 49.61~49
．． It was possible to control it within the range of 92-. We also investigated the number of defects in the obtained ingots based on the sweating phenomenon.
The results are compared with the number of defects in ingots cast under constant conventional casting conditions and shown in Figure 6 (A) Number of defects in ingots continuously cast by the method of the present invention; Fi
As can be seen from the figure, the average number of defects in the conventional method (by the conventional method) was 53 points, while the present invention With the method, the average number of defect points (ri) has been significantly reduced to 24 points.In contrast to the conventional method, where the variation in the number of defect points is very large, with the method of the present invention, the variation in the number of defect points is small. Understand - In the example, 10 shows an example in which the ingot thickness was controlled so that the sum was 49.6 cm or more, but based on Fig. 1, the ingot thickness: #49.4 ■When the number of defects is more than #i
Since there were no similar problems with 80 or less and the quality of the product, the ingot thickness was 49.4 mm for the mold internal dimension of 50 mm, and the ratio should be controlled to Δ, which is the sum of 98.8 mm or more. .

In the above, the thickness of the ingot was continuously measured and displayed, and the amount of water in the final cooling zone was manually increased or decreased, but the method is not limited to this and may be controlled automatically. Furthermore, although the explanation has been made regarding the continuous production of A4 alloy, the present invention is not limited to this and can be applied to all metals and alloys.

As described above, according to the present invention, it is possible to significantly improve the quality of the ingot by preventing the sweating phenomenon, improve productivity by improving cracking during rolling processing, wire breakage during stretching processing, etc., and further reduce the mechanical properties of the product. It can improve the effects and fluctuations, etc., and has a significant industrial effect.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing the relationship between the thickness of an ingot continuously cast by a conventional method and the number of defects, Fig. 2 is an explanatory diagram showing an example of the method of the present invention, and Fig. 3 is an explanatory diagram showing an example of the method of the present invention. An example of the original bed diagram and iris diagram ←) to (d) show the operating state 11 of the measuring device shown in Figure 3, where (a) shows the ingot running normally, and (b) shows the top and bottom. If the displacement is parallel to , (e) ij is displaced downward, (d) ti is displaced upward 1! Fig. 5 is an explanatory diagram showing the relationship between the amount of cooling water in the final cooling zone, the ingot temperature K, and the ingot thickness in the method of the present invention. FIG. 3 is an explanatory diagram showing the change over time in the number of defects in a cast piece. l・・・・・・Rotating wheel for mold 2・・・・・・・・・・Guide wheel 41---Hearing・Fish roll 3 Iris・・・・・・・・・・-...Gold 4 Endless belt 5...
...... Mold 6 ...... Cooling zone 8 -----...
...Ingot 9...--Ingot thickness measuring device 12...
...Continuous rolling mill 13... Winder 18... Guide rolls 25, 26...
・Detection roll 29...Differential displacement needle Fig. 4

Claims (1)

[Scope of Claims] (1) A mold is continuously formed by a rotary mold ring having a concave groove on its circumference and a metal endless belt that comes into contact with the peripheral surface of the ring, and a mold is continuously formed inside the mold. In the method of pouring molten metal from two ends of the mold, spraying cooling water around the base to cool and solidify the molten metal 1k, and taking out a lump from the other end of the mold, the thickness of the taken out ingot is kept constant, A continuous casting method in which the casting conditions are controlled so that the thickness is as close as possible to the internal thickness of the mold.Q) All casting conditions except the amount of cooling water are kept constant The continuous casting method according to claim 1, in which the amount of cooling water is controlled by controlling the amount of cooling water. Continuous casting method according to item 2. (4) The upper surface of the ingot cast from the mold is brought into contact with the lower fJK detection roll, and a differential displacement needle is provided at both a-rules, and at least one of both rolls is provided with an ingot according to the displacement of the ingot. Claims 1, 2, or 3, in which the ingot thickness is measured by attaching a following guide and holding the contact points of both rolls with the ingot directly in the longitudinal direction of the ingot. The continuous casting method described.