JPS6012270A - Adjusting method of casting temperature - Google Patents

Abstract

PURPOSE:To obtain an excellent casting in the stage of pouring molten copper from a holding furnace into a casting mold by reading the temp. rising speed of spouts provided before and behind the holding furnace and controlling the temp. of the molten copper to be supplied into the casting mold. CONSTITUTION:A temp. detector is attached to a spout 2 which conducts the copper melted in a shaft furnace 1 to a holding furnace 3 and/or a spout 4 which conducts the molten copper from the furnace 3 to a tundish 5, etc. The temp. rise DELTAt deg.C at the time DELTAH is then measured. A copper wire calculated preliminarily to meet the measured DELTAt/DELTAH is supplied to a molten metal well 6 in accordance with the change in the speed of a pinch roll 9 driven by a motor 8, thereby controlling the temp. of the molten copper to be supplied into the casting mold.

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 possible to efficiently produce high-quality castings by controlling the temperature.

By the way, a schematic diagram of the process from melting copper to casting is shown in Fig. 1.

That is, the copper melted in the shaft furnace 1 passes through the first gutter 2 and enters the holding furnace 3, where hot water is stored and the amount and temperature of the casting hot water are approximately adjusted. The molten metal flows through a gutter 4 to a ladle or tundish 5, where the amount and pool of molten metal are finely adjusted and supplied to a casting machine (not shown) for casting.

However, 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. After the copper is poured into the mold, sushi-shaped crystal growth can be seen as shown in Figure 2.However, it is desirable that the casting temperature be as low as possible without degrading the casting surface in terms of quality.
In order to maintain good quality of the cast 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 or the like.

Further, if the casting temperature is, for example, 1i20° C. or lower, the casting temperature is too low, and there is a risk that gas may not be completely removed from the cast product and cavities may be formed.

In other words, the temperature of the copper coming out of the shaft furnace will be lower if the melting is good, and higher if the melting is poor.
The temperature at which the copper melts differs depending on the size of the electric steel.

That is, the raw materials melted in a shaft furnace include electric steel, bar steel, and steel, and there are also various brands of electric copper, and they have different shapes.

For this reason, the melting speed of copper differs depending on the raw material copper, and the temperature of the copper melting p1 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 dissolved, and a tundish or ladle size corresponding to the size of the tundish or ladle is installed in each furnace to measure the temperature of the hot water. Although the combustion valve of the holding furnace was opened and closed, the current situation is that temperature differences of up to 60°C still occur, and this can cause various problems such as roughening of the casting surface and embrittlement of the casting. A problem remained.

The present invention has been made in order to solve this further drawback of the conventional art.

That is, the explanation will be as follows with reference to Figure 3 of the present invention.

The copper melted in the shaft furnace passes through the first gutter 2 and is transferred to the holding furnace 3.
At the beginning of the process, hot water is stored in the tank, the amount and temperature of the casting hot water are approximately adjusted, and the water is passed through the first hot water pool 7, the second hot water pool, and the gutter 4 to the tundish or water tank 5. It has become. 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 in order to increase the response speed.If the temperature fluctuation is large, it is recommended 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, read the line of temperature increase by △t℃ in △H time, and set the motor (
The temperature is controlled by changing the speed of the pinch rolls 9 driven by direct current (DC) 8 so that the required amount of copper wire is continuously supplied.

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

In addition, when the temperature decreases significantly, the opening degree of the rotary nozzle 11 of the nozzle 10 attached to the holding furnace 3 is automatically adjusted by a signal given to the DC motor 12, and the burner 10 is What is necessary is to perform control in accordance with the gradient of the gas amount τthH.

The preferred means for controlling temperature is a microcomputer.
It is to take advantage of. Figure 4 is a complete flowchart.

According to this jL, for example, when setting the hot water temperature k1120℃ and controlling the upper limit value i + 5℃ and the lower limit value to -3℃, the working time, △H waiting time temperature 1ro, and current temperature. The predicted temperature °r2 9611 hours after the current time is calculated from fTt.

- The temperature drop when a certain amount of copper wire is inputted as a correction material xg (xm if the wire diameter is fixed) has been experimentally confirmed and input into the microcomputer, so
When there is a possibility that the predicted temperature T2 after the ΔH waiting time exceeds the control limit of +5°C, a predetermined high-speed signal is applied to the motor 8 that drives the pinch roll 9 made of copper wire that is the temperature correction material. , to maintain a predetermined temperature range. 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 copper wire, which is the temperature correction material, to reduce or stop the supply of copper wire. to control the temperature within the specified range. By doing this, there is no need for Iruma to be placed directly near the holding furnace for temperature control, and it is only necessary to watch a single image projected on a cathode ray tube connected to the computer. .

If the temperature drops abnormally, a computer signal is used to send a signal to the motor 12 to open the rotary nozzle 11 of the nozzle 10 attached to the holding furnace 3 and raise the temperature. A more preferred operation is to also control the amount of gas in the toner to correspond to the slope of the island.

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 suppressed to 20°C, whereas the conventional method generates a temperature of 50°C or more. It will be understood that the conventional method produces defects on the surface of the ingot.

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

Here, the number of defects on the surface of the ingot is 10 when inspected with an eddy current flaw detector.
~When you catch a signal of 20 earthquakes, score 1 point at '5c, and 2 points.
3 points are given when a signal of 0 to 30 is caught, and 30
When a signal of W or more is caught, it is evaluated as 5 points,
Ingot 10! The correlation with the forging temperature was investigated by displaying the number of defects on the ingot.When the casting temperature is between 1120℃ and 1140℃, the number of surface defects on the ingot is It can be said that this proves that the method according to the present invention shown in FIG. 5 is an extremely superior method.

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. This makes it possible to provide a cast product that is significantly superior to conventional ones.

[Brief explanation of drawings]

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. Figure 4 is a flowchart of the present invention. Figure 5 is a graph of casting temperature versus working time between the method of the present invention and the conventional method. Figure 6 is a graph of casting temperature versus number of surface defects in ingots. 1...Shaft furnace, 2 ...First gutter, 3...Holding furnace, 4...
・Second gutter, 5... tundish or shidol, 6.
...Second water reservoir, 7...First water reservoir, 8...DC motor, 9...Vinch roll, 10...Nono-ner, 11...Rotary nozzle , 12... DC motor agent Patent attorney Mamoru Takeuchi Figure 2

Claims (1)

[Claims] When the copper melted in the shaft furnace is led to the holding furnace and poured into the mold from the tundish or caster, a temperature detector is installed in one or both of the gutter located before and after the holding furnace to keep the temperature at ΔH. The temperature rise Δt°C during the waiting time is read, and the speed change of the pinch roll, which is driven by a motor, moves a pre-calculated amount of copper wire at the hot water tank just before the gutter at the end of the holding furnace. and supply accordingly.
A method for regulating a casting temperature, characterized in that the temperature of molten steel supplied to a casting machine is thereby controlled.