JPH04105753A - Continuous casting method - Google Patents

Abstract

PURPOSE:To improve cold-workability by working a cast billet with continuous casting in the specific rolling reduction ratio at the specific temp. CONSTITUTION:In the continuous casting by cooling and solidifying molten metal 8 in a casting furnace 2 in a mold 1 for continuous casting, which opens both ends and is fitted while connecting with the casting furnace 2, to make the cast billet 3 and continuously drawing this cast billet 3 with pinch rolls 5, 6, which set in front of the mold 1, the rolling reduction working having >=15% rolling reduction ratio is executed to the cast billet 3 produced from the mold 1 with the pinch rolls 5, 6 at the recrystallizing temp. or higher of the produced cast billet. By this method, the cast billet having rich cold- workability and being unnecessary to heat treatment, such as soaking, is obtd.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a continuous casting method that can easily produce an ingot with excellent cold workability.

[Conventional technology and its issues]

A continuous casting method in which a mold with both ends open is installed in communication with a casting furnace, and the molten metal supplied from the casting furnace is cooled and solidified in the mold to form an ingot, which is continuously pulled out by pinch rolls. is widely used for casting metal materials such as copper and aluminum.

Incidentally, the ingots produced by the above-described continuous casting method are generally small in size, and therefore cold processing such as wire drawing is performed in subsequent steps.

However, the produced ingot has a cast structure in which alloying elements and impurity elements are segregated, so if it is cold-worked as it is, defects such as orange cracks and cracks will occur, and in the case of hard-to-work materials such as phosphor bronze, cold-working The ingots broke during processing and could not be processed at all, so a so-called soaking process was performed to heat the ingots for a long time before cold working.

However, this soaking treatment is not only disadvantageous in terms of energy, but also significantly reduces productivity, and there has been a strong demand for improvement measures.

[Means to solve problems]

The present invention was made in view of the above situation, and an object of the present invention is to provide a continuous casting method in which the casting structure is destroyed and an ingot with excellent workability can be obtained.

That is, the present invention cools and solidifies molten metal in a casting furnace in a continuous casting mold with both ends open, which is installed in communication with the casting furnace, to form an ingot, and the ingot is poured into an ingot at the front of the mold. In a continuous casting method in which the ingot is continuously drawn out using arranged pinch rolls, the ingot produced from the mold has an area reduction rate of 15%.
The method of the present invention is characterized in that the above surface-reducing process is performed using the pinch rolls at a temperature higher than the recrystallization temperature of the produced ingot. At a temperature higher than the recrystallization temperature of the ingot, the ingot is rolled down with an area reduction of 5% or more using pinch rolls for drawing out the ingot to destroy the cast structure of the ingot and improve cold workability. However, according to this method, since the temperature of the produced ingot is originally high, it is easy to bring the ingot to a temperature higher than the recrystallization temperature, and the reduction of the ingot is Since it is carried out using pinch rolls for pulling out lumps, it is advantageous in terms of equipment.

In the method of the present invention, methods for setting the temperature of the produced ingot to a temperature higher than the recrystallization temperature include a method in which the length of the mold is shortened and the ingot is produced at a high temperature, and a method in which the ingot is produced at a high temperature with the length of the mold shortened. There is a method of reheating the ingot by placing an ingot heater at the outside of the mold, but in any case, a heater or cooler is installed around the outside of the mold to make it possible to control the mold temperature. It is preferable to be able to freely control the temperature of the mass.

The reason for limiting the area reduction rate of the produced ingot to 15% or more and the reduction temperature to a temperature equal to or higher than the recrystallization temperature of the produced ingot in the method of the present invention is that even if any of the conditions are absent, This is because the casting &lI weave of the obtained ingot is not destroyed and the cold workability is not improved.

The method of the present invention will be specifically explained below with reference to the drawings.

FIG. 1 is an explanatory side view showing an embodiment of a continuous casting apparatus used in the method of the present invention. In the figure, 1 is a mold, 3 is an ingot, and 5.6 is a pinch roll.

A mold 1 with both ends open is connected to a casting furnace 2 at two ends thereof, and a cooler 4 is provided around the outer periphery of the mold 1. Further, in front of the mold 1, two pinch rolls 5 and 6 whose shafts are mounted horizontally or vertically are arranged, respectively, and an ingot heater 7 is arranged between the mold 1 and the pinch rolls 5.

The molten metal 8 supplied from the casting furnace is cooled and solidified in the mold 1 cooled by the cooler 4 to become an ingot 3, and this ingot 3 is heated to a predetermined high temperature in the ingot heater 7. After being heated, it is pulled out and rolled down by pinch rolls 5 and 6.

In the above, the reason why two pinch rolls are arranged is because it is assumed that the round bar-shaped produced ingot will be made into a round bar shape even after being rolled down by the pinch rolls, and when the produced ingot has a rectangular cross section. etc., even one pinch roll can be made into a round bar shape.

[Effect]

In the method of the present invention, the produced ingot is pressed down at a temperature higher than the recrystallization temperature of the produced ingot by pinch rolls for drawing out the ingot to destroy the cast structure, so the obtained ingot is cold-processed. It is rich in properties and does not require heat treatment such as soaking.

Also, since the ingot produced from the mold is originally at a high temperature,
It is easy to bring the ingot to tJ4# above the recrystallization temperature, and the ingot is rolled down using pinch rolls for drawing out the ingot, which is advantageous in terms of equipment.

【Example〕

The present invention will be explained in detail below using examples.

Example 1 Using the continuous casting apparatus shown in Fig. 1, the drawing time was 0.2 s.
ec, stop time 0.8 sec, withdrawal speed 40mm/w
Oxygen-free copper ingots were continuously cast using an intermittent drawing method.

The diameter of the produced ingot and the amount of reduction by the pinch rolls were varied, and the reduction temperature was adjusted to a predetermined temperature by a heater placed in front of the mold. Note that a graphite mold was used as the mold.

The obtained ingot was then processed into a 2.6mm ingot by cold wire drawing.
Defects were investigated using an eddy current flaw detector using a φ wire rod.

Furthermore, the wire was drawn to an ultra-fine wire of 50-φ, and the amount of wire drawn per wire breakage was determined. The results are shown in Table 1 along with the main manufacturing conditions.

As is clear from Table 1, products manufactured using the method of the present invention (N01-6)
It was confirmed that the 2.6 mmφ material had a small number of defects and had good wire drawability as an ultra-fine wire. Among them, the higher the rolling temperature or the rolling ratio, the better the wire drawability was obtained. In addition, when the structures of the ingots were observed, they all had recrystallized structures in which the casting structures were destroyed.

On the other hand, the comparative products Nα7 to Nα9 had a large number of defects in the 2.6 mmφ material, and the ultra-fine wires had frequent disconnections and were inferior in wire drawability. This is because in the former two cases, the reduction rate by the pinch rolls was less than 15%, and in the latter case, the reduction temperature was below the recrystallization temperature of the produced ingot, so in both cases the casting structure was not sufficiently destroyed. be.

When the structures of the ingots were observed, a considerable amount of casting structure remained in all of them.

Example 2 In Example 1, the withdrawal speed of the ingot withdrawal condition was set to 30+w.
A phosphor bronze ingot (8% tin, 0.25% phosphorus, balance copper) was produced in the same manner as in Example 1, except that the thickness was changed to m/l 1 inch.

The obtained ingot was drawn to a diameter of 4.8 mm, and its quality was examined using an eddy current flaw detector.

The results show the main manufacturing conditions They are also listed in Table 2.

As is clear from Table 2, the product produced by the method of the present invention (N.

10 to 1.5) had few defects and had good quality. As in Example 1, the number of defects in the 4.8 mmφ material tended to decrease as the rolling reduction rate or rolling temperature increased.

On the other hand, the comparison method product has a low rolling reduction (Nctl, 61
7) Or because the rolling temperature is below the recrystallization temperature (Nα18),
In all cases, the casting structure was not destroyed and many defects occurred in the 4.81φ material.

The above description has been made of the case of intermittent drawing of oxygen-free copper or phosphor bronze, but the method of the present invention can also be applied to the casting of metal materials such as brass and aluminum alloy, or to continuous drawing without stopping. It is effective.

[Effects] As described above, according to the method of the present invention, an ingot with excellent cold workability can be efficiently produced, and a remarkable effect is produced industrially.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of main parts showing an example of an embodiment of an apparatus for carrying out the method of the present invention. 1...mold, 2...casting furnace, 3...ingot,
4...Cooler, 5,6...Pinch roll, 7
... Ingot heater, 8... Molten metal.

Claims (1)

[Claims] The molten metal in the casting furnace is cooled and solidified into an ingot in a continuous casting mold with both ends open and connected to the casting furnace, and the ingot is continuously cast by pinch rolls placed in front of the mold. In the continuous casting method, the ingot produced from the mold is subjected to surface reduction processing with an area reduction rate of 15% or more using the pinch rolls at a temperature equal to or higher than the recrystallization temperature of the produced ingot. Continuous casting method.