JPH0245544B2 - CHUZOONDONOCHOSETSUHOHO - Google Patents

Description

Detailed Description of the Invention Shaft furnaces are widely used as copper melting furnaces because of their excellent thermal efficiency during melting. It is necessary to efficiently produce high-quality cast bars by controlling the temperature.

By the way, FIG. 1 shows a schematic diagram of the process from melting copper to casting.

That is, the copper melted in the shaft furnace 1 is transferred to the first gutter 2.
The hot water enters the holding furnace 3, where the hot water is once stored, and the casting hot water amount and hot water temperature are roughly adjusted here.The hot water then passes through the second gutter 4 to the ladle or tundish 5, where the hot water amount and pool are slightly adjusted. It is adjusted, supplied to a casting machine (not shown), and cast.

By the way, when casting using this method, there is a large variation in temperature at the pouring point, resulting in a temperature difference of up to 60°C. The copper poured into the mold then shows streak-like crystal growth as shown in Figure 2, but it is desirable to keep the casting temperature as low as possible within a range that does not deteriorate the casting surface in terms of quality, to ensure good casting. In order to maintain the quality of the product, it is necessary for a worker to be present at the first gutter 2 and to adjust the temperature by filling it with metal, etc.

Further, if the casting temperature is, for example, 1120° C. or lower, the casting temperature is too low, and there is a risk that gas may not be able to escape from the cast product and cavities may form.

In other words, the temperature of the copper coming out of the shaft furnace is lower if it melts well, and higher if it melts poorly, but the temperature of the copper that melts differs depending on the size of the electrolytic copper.

That is, the raw materials melted in the shaft furnace include electrolytic copper, rod copper, scrap copper, etc., and electrolytic copper also comes in various brands and has different shapes.
For this reason, the melting speed of copper differs depending on the raw material copper, and the temperature of the melted copper also differs.

Therefore, the size of the holding furnace and the size of the tundish or ladle are determined according to the amount of copper melted, and a burner corresponding to the size of the tundish or ladle of the furnace is installed, and the temperature of the hot water is measured while the holding furnace burns. Although the valves were opened and closed, there was still a temperature difference of up to 60°C, which caused problems such as roughening of the casting surface and embrittlement of the casting. be. The present invention has been made to solve these conventional drawbacks.

That is, the present invention will be explained as follows with reference to FIG.

Copper melted in the shaft furnace passes through the first trough 2 and enters the holding furnace 3, where the hot water is once stored and the amount and temperature of the casting molten metal are roughly adjusted. It is designed to reach a tundish or ladle 5 via a basin 6 and a gutter 4. Here, a temperature detector is attached to the arrow part of the first gutter 2 or the second gutter 4 to measure the temperature of the water. In this case, it is preferable to use a sheathed thermocouple as the temperature detector to increase the response speed, and if the temperature fluctuations are large, it is better to attach thermometers to both the first gutter 2 and the second gutter 4. It can be said that it is preferable.

Next, by installing this thermometer, △t℃ at △H time
The speed of the pinch roll 9, which is driven by a motor (DC) 8, is adjusted so as to read the line of temperature increase by 300 mL and supply the second sump 6 with copper wire calculated in advance to match Δt/ΔH. The temperature is controlled by the change so that the required amount of copper wire is continuously supplied at all times.

Of course, as an applied operation of the present invention, if the increase value of △t/△H is significantly large, it is possible to increase the cooling effect by using multiple supply lines or thickening the supply copper wire. .

In addition, if the temperature decreases significantly, the rotary valve 11 of the burner 10 attached to the holding furnace 3
The opening degree of the DC motor 12 may be automatically adjusted by a signal given to the DC motor 12, and the gas amount of the burner 10 may be controlled in accordance with the gradient of Δt/ΔH.

A preferred means of temperature regulation is through the use of a microcomputer. FIG. 4 shows the flowchart.

According to this, for example, if the water temperature is set to 1120℃,
When controlling the upper limit to +5℃ and the lower limit to -3℃, the working time, the temperature T ₀ before △H time, and the current temperature T ₁ from the current △H
The predicted temperature T ₂ after the time is calculated.

On the other hand, the temperature drop when xg (xm if the wire diameter is fixed) of a certain copper wire as a correction material is input into the microcomputer has been experimentally confirmed and entered, so When the predicted temperature T ₂ is likely to exceed the control limit of +5°C, use a pinch roll 9 of copper wire, which is the temperature correction material mentioned above.
Give a predetermined high-speed signal to the motor 8 that drives the
Ensure that the temperature is within the specified temperature range. In addition, if the temperature is predicted to drop and reach the lower limit, a signal is sent to the motor 8 that drives the pinch roll 9 of the copper wire, which is the temperature correction material, to reduce or stop the supply of copper wire. temperature control within the specified range. By doing this, there is no need for humans to be placed directly near the holding furnace to control the temperature, and they only have to watch the image displayed on the cathode ray tube connected to the computer. If the temperature drops abnormally, a signal from the computer is used to open the rotary valve 11 of the burner 10 attached to the holding furnace 3 and send a signal to the motor 12 to raise the temperature, thereby reducing the amount of gas in the burner by △t. A more preferable operation is to use control in accordance with the gradient of /ΔH.

Next, an example of variation in casting temperature between the method according to the present invention and the conventional method is shown in a graph as shown in FIG.

That is, according to the method of the present invention, the maximum width of the temperature difference is 20
℃ compared to 50℃ using conventional methods.
It will be understood that the quality of the cast copper produced by the method of the present invention is superior since temperatures above .degree. C. are produced, whereas those produced by the conventional method produce defects on the surface of the ingot.

Next, the relationship between the casting temperature and the number of surface defects in the ingot was investigated and a graph is shown in FIG. 6.

Here, the number of defects on the surface of an ingot is measured using an eddy current flaw detector, and one point is scored when a signal of 10 to 20 mm is caught, three points are scored when a signal of 20 to 30 mm is caught, and a signal of 30 mm or more is scored as one point. The evaluation is given as 5 points when caught, and the correlation with casting temperature is investigated by displaying the number of defects per 10 m of ingot. It is clearly shown that the number of surface defects in the ingot is the lowest, and it can be said that this proves how superior the method according to the present invention shown in FIG. 5 is.

As described above, according to the present invention, the temperature control before and after the holding furnace can be automatically performed using relatively simple means so that the temperature is within a certain controlled temperature range. Therefore, it is possible to provide a cast product that is significantly superior to that of the conventional method.

[Brief explanation of the drawing]

Fig. 1 is a schematic explanatory diagram of a conventional copper casting process, Fig. 2 is a cross-sectional view of copper poured into a mold, and Fig. 3 is a schematic explanatory diagram of a copper casting process showing an example of the present invention. FIG. 4 is a flowchart of the present invention, FIG. 5 is a graph of casting temperature versus working time for the method of the present invention and a conventional method, and FIG. 6 is a graph of casting temperature versus the number of surface defects in an ingot. 1...Shaft furnace, 2...First gutter, 3...Holding furnace, 4...Second gutter, 5...Tundish or ladle, 6...Second sump, 7...First gutter Hot water reservoir, 8...DC motor, 9...pinch roll,
10...Burner, 11...Rotary valve, 1
2...DC motor.

Claims (1)

[Claims] 1. Leading copper melted in a shaft furnace to a holding furnace,
When pouring metal into a mold from a tundish or ladle, a temperature detector is attached to one or both of the troughs located before and after the holding furnace to read the temperature rise Δt°C in time ΔH. A pre-calculated amount of copper wire corresponding to △t/△H is supplied to the pool just before the casting machine in accordance with the speed change of the pinch roll driven by the motor. A method for adjusting casting temperature, characterized in that the temperature of molten copper is controlled.