JPH07214271A - Device for supplying molten magnesium - Google Patents

Abstract

PURPOSE:To provide a molten magnesium supplying device provided with a molten metal supplying pipe heating device inexpensive in equipment cost and capable of executing safe and simple treatment. CONSTITUTION:This molten magnesium supplying device 1 is provided with an electric-conductive metal-made molten metal supplying pipe 14 arranged at the outside of a furnace and wound with a coated electric conductive lead wire 30 in spiral state and the molten metal pipe heating device 100 consisting of a transformer 50 for AC electric source 40, program setter 70, temp. indicating and regulating meter 80 and controller 60, and executing low frequency induction heating with low voltage and high current by conducting the electric power to the lead wire 30. Thus the heating coil is simply fabricated.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnesium hot water supply apparatus, and more particularly to a magnesium hot water supply apparatus provided with a heating apparatus for a hot water supply pipe by low frequency induction heating.

[0002]

2. Description of the Related Art Conventionally, an inert gas is supplied into a melting furnace as shown in FIG. 3 to prevent the oxidation of molten magnesium, and an injection piston 6 in an injection sleeve 5 is lowered to remove a fixed amount of molten magnesium. A magnesium hot water supply device 1 has been proposed in which it is supplied into a die casting sleeve 20 of a die casting machine via a hot water supply pipe 10. In this apparatus, solidification of molten magnesium at 650 to 700 ° C. during hot water supply is prevented, and a heater 18 is attached over the entire length of the outer periphery of the hot water supply pipe 14 outside the furnace where the molten magnesium is smoothly guided to the die casting sleeve 20 to keep heating and heat. Alternatively, the hot water supply pipe 14 outside the furnace was heated by a gas burner to raise the temperature.
However, since the flame of gas rises from the lower side to the upper side when heating the outside hot water supply pipe 14 with the gas burner, the heating from the lower side is easy, but the heating from the upper side is difficult. However, it is difficult to uniformly heat the outer circumference of the hot water supply pipe 14 outside the furnace by either manual heating work or fixed equipment, resulting in poor workability and thermal efficiency. Further, in the heater 18 that is wound by a nichrome wire or the like,
There are many breaks at the joints such as nichrome wire during winding work,
Also, there were many disconnections during use, which hindered maintenance.
In order to solve such a problem, in recent years, a method of heating a hot water supply pipe based on the principle of induction heating has been tried.

[0003]

However, in order to inductively heat the hot water supply pipe outside the furnace, it is necessary to wind a heating coil, through which an alternating current is passed in order to form an alternating magnetic flux, around the outer circumference of the hot water supply pipe in a non-contact manner. Yes, and for rapid heating, high voltage, high current, high frequency (150-1000)
Since the induction heating is performed at 0 Hz), conventionally, a copper pipe is used to prevent thermal burnout of the heating coil, and cooling water or cooling air is passed through the inside of the heating coil to cause abnormal heating of the heating coil (1000 to 2000
℃) had to be prevented. However, since the hot water supply pipe outside the furnace has a plurality of curved points and is often bent in a complicated curved shape depending on the arrangement of the hot water supply device and the die casting sleeve of the die casting machine that follows it, the heating coil (copper pipe) is often used. It is very difficult to wind the hot water supply pipe around the thyristor inverter (150 to 1000) as a power source for generating high frequency for high frequency induction heating.
0 Hz), a vacuum tube oscillator (100 to 500 kHz), a transistor inverter, etc. are required, and there has been a problem that the initial payment (equipment cost) of the heating device for the hot water supply pipe becomes expensive. Further, there is a risk of steam explosion of molten magnesium due to leakage of cooling water from the joint portion of the copper pipe which is the heating coil, and there was a safety problem as well as an electric shock accident to the heating coil.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a heating device for hot water supply pipes which solves the above problems, reduces equipment costs, and has higher safety. In a magnesium hot water supply apparatus for supplying molten magnesium stored in a melting furnace through a hot water supply pipe communicating with the outside, the hot water supply pipe is made of a conductive metal, and the outer circumference of the hot water supply pipe is covered with a conductor of a covered electric wire. In addition to winding the coil in a spiral shape, a transformer that converts the AC voltage to a low voltage, a program setting device that sets the connection and disconnection of energization, and a temperature instruction adjustment that receives the detection signal of the temperature sensor arranged on the outer peripheral surface of the hot water supply pipe And a temperature indicator controller and a controller connected to the program setter, the hot water supply box performing low frequency induction heating by energizing the conducting wire of low voltage and high current. Those having a heating device flop.

[0005]

According to the present invention, a normal covered electric wire is wound around a hot water supply pipe which is passed through when the high temperature molten magnesium melted inside the magnesium hot water supply device is discharged to the outside to energize the hot water supply pipe at a low frequency. The temperature of the hot water supply pipe is maintained at the same temperature as molten magnesium (about 700 ° C.) and the molten magnesium is discharged without lowering the temperature. Further, after the discharge of molten magnesium corresponding to the amount of hot water supplied for one shot is completed, the temperature can be automatically controlled by the attached program setting device or controller so as to maintain the set temperature until the next shot.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 relate to an embodiment of the present invention,
FIG. 1 is an overall longitudinal sectional view of a magnesium water heater, and FIG. 2 is an explanatory view showing the principle of induction heating. In FIG. 1, a magnesium hot water supply device (hereinafter referred to as a hot water supply device) 1 is an upright cylindrical melting pot 2 that is housed inside a melting furnace 3 and has a lid 4, and is vertically installed inside the melting pot 2. An injection sleeve 5 having an injection piston which is open at both ends and is slidable inside;
A hot water supply pipe 10 that has an opening 10a at one end and is connected orthogonally to the lower end of the injection sleeve 5 and extends outside the furnace, and a molten magnesium (hereinafter referred to as molten metal) 8 to the opening 10a of the hot water supply pipe 10 communicate with each other. It is composed of a suction valve 7 for shutting off and a check valve 25 in the middle of the hot water supply pipe 10. The injection piston 6 and the piston rod 1 are on the lid 4.
The injection cylinder 11 connected via 2 and the valve cylinder 16 connected via the suction valve 7 and the valve rod 17 are stacked and fixed, and injection for injecting the inert gas into the melting furnace 2 is performed. A tube 9 is attached. The injection sleeve 5 forms a pressurizing chamber for taking out the molten metal 8 in the melting pot 2 to the outside of the furnace, closes the suction valve 7 and lowers the injection piston 6 to fill the molten metal in the hot water supply pipe 10. 8a is conveyed to the outside of the furnace via the hot water supply pipe 10, is discharged into the die casting sleeve 20 near the outside of the furnace via the hot water supply pipe 14 of the hot water supply pipe 10 and the outlet portion 15, and is advanced by the die casting piston 21. It is poured into a die of a die casting machine (not shown).

On the other hand, the hot water supply pipe 1 outside the furnace hot water supply pipe 1
4 is a pipe diameter of 40 to 50 m, such as an alloy steel pipe for piping (STPA) or a carbon steel pipe for high temperature piping (STPT).
m, a steel pipe having a wall thickness of about 4 to 6 mm is used, the circumference of which is insulated by a heat insulating material 26 and a conductor wire 30 such as a covered electric wire insulated around the outer circumference is wound in a coil shape, and both ends thereof are controlled by the controller 6
Connect to 0. On the other hand, the AC power supply 40 has a commercial frequency (50
(Or 60 Hz), the voltage is dropped to 25 V by the transformer 50 and connected to the controller 60. The temperature indicating controller 80 is connected to the temperature sensor 80 a provided on the outer peripheral surface of the hot water supply pipe 14 and then to the controller 60. In addition, the controller 60 compares the heating condition of the hot water supply pipe 14 input to the program setting device 70 in advance with the actual measured temperature transmitted from the temperature indicating controller 80, and then the AC temperature is adjusted according to the instruction. Power on 40
-OFF control is performed to control the temperature of the hot water supply pipe 14 outside the furnace. The above conducting wire 30, transformer 50, controller 6
0, the program setting device 70, the temperature indicating controller 80, etc. are collectively referred to as the hot water supply pipe heating device 100.

FIG. 2 shows the principle of induction heating. When an alternating current is passed through a heating coil A connected to an AC power source B, an alternating magnetic field D is generated in an object to be heated C placed therein. ,
An eddy current E is induced in the object to be heated by an electromagnetic induction action.
The heating method using the Joule heat of the eddy current E is induction heating, and the object to be heated needs to be a conductive substance. The depth of the heating layer due to the eddy current E is related to the frequency of the current flowing through the heating coil A. If the frequency is high, the heating layer concentrates on the surface, and if the frequency is low, it penetrates to the inside. This is a phenomenon called the skin effect of alternating current, and the heating frequency is selected in consideration of the purpose of heating, the size of the object to be heated, etc. Normally, the commercial frequency (50 or 60 Hz) to 500 kHz is used. A heating device to which induction heating is applied is used for thermal processing such as forging, extrusion, rolling, brazing and welding, and for heat treatment such as quenching, tempering, normalizing and annealing. Both total heating and local heating are possible by selecting the heating frequency and the heating coil. The induction furnace used for melting metals is capable of rapid melting and also utilizes the electromagnetic stirring action of the molten metal, which is effective for adjusting the components and degassing. Depending on the frequency, it can be divided into a low-frequency furnace and a high-frequency furnace, but the high-frequency furnace is overwhelmingly predominant due to the nature of metal melting. In the present invention, in consideration of the fact that the molten magnesium temperature is a relatively low temperature of 700 ° C., low frequency induction heating that does not require water cooling, which is indispensable as a measure against thermal burnout of the heating coil in the conventional high frequency heating, is adopted. The heating coil was stopped from being a copper tube that is difficult to bend, and a commercially available bendable covered electric wire that is usually commercially available was used as the heating coil. Therefore, the adopted frequency is 50Hz or 6
The normal commercial frequency is 0 Hz. As for the working voltage, the AC power source 40 of 100V is dropped to 25V by the transformer 50, and the current value flowing through the conducting wire is about 360A. In the hot water supply pipe heating apparatus 100 of the present invention that employs low frequency heating with such a low voltage and high current, the temperature rise of the conductor 30 is 60 to 80.
The outside-furnace hot water supply pipe 14, which is an object to be heated, can be heated to a temperature of about 600 to 750 ° C. at a relatively low temperature of about 0 ° C.

In the magnesium hot water supply apparatus 1 of the present invention constructed as described above, the hot water supply pipe heating device 100 is energized to preheat the outside hot water supply pipe 14 before the operation of the melting furnace 3, and the temperature sensor 80a. Thus, the operation starts when the outside hot water supply pipe 14 reaches a predetermined target temperature (700 ° C.). Then, during the operation, the controller 60 automatically controls the ON / OFF control of the power supply interruption so that the target temperature is input to the program setting unit 70 in advance. In the present invention, a commercially available insulation-coated electric wire can be used as a conducting wire without using a conventional copper coil of a heating coil for high-frequency induction heating, so that the conducting wire can be directly used for a hot water supply pipe having a large degree of bending. As it can be wound, it is very easy to install. In addition, since the conductor wire 30 is a covered electric wire, it is safe, and even if the worker comes into contact with the bare conductor wire while energized, the voltage is as low as 25V, and the current value flowing to the human body is about 12 mA (human body resistance value 2100 ohms. ), Which is less than the lethal electric shock (50 mA for 3 seconds), the risk of electrocution is small and the safety is high. Moreover, since expensive equipment such as a frequency switch is not required, the equipment cost is small.

[0010]

In the magnesium hot water supply apparatus of the present invention, since the hot water supply pipe is low-frequency, high-current, low-frequency induction heated, the construction of the heating coil (coated wire) is simple and the equipment cost is low. . In addition, the safety of electric shock accidents is much higher than before. Further, since the temperature control of the hot water supply pipe can be automatically controlled by a simple ON-OFF control, the operation control is easy.

[Brief description of drawings]

FIG. 1 is an overall vertical cross-sectional view of a magnesium water heater according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the principle of induction heating according to the embodiment of the present invention.

FIG. 3 is an overall vertical sectional view of a conventional magnesium water heater.

[Explanation of symbols]

 1 Magnesium Hot Water Supply Device 2 Melting Pan 3 Melting Furnace 4 Lid 5 Injection Sleeve 6 Injection Piston 7 Suction Valve 8 Molten Magnesium 9 Inert Gas Injection Pipe 10 Hot Water Supply Pipe 10a Opening 11 Injection Cylinder 12 Piston Rod 14 External Hot Water Supply Pipe 15 Pipe outlet 18 Heater 20 Die-casting sleeve 21 Die-casting piston 25 Check valve 26 Insulation material 30 Conductor wire 40 AC power supply 50 Transformer 60 Controller 70 Program setting device 80 Temperature indicator controller 80a Temperature sensor 100 Hot water supply pipe heating device A Heating coil B AC Power source C Heated object D Alternate magnetic flux E Eddy current

Claims (1)

[Claims] 1. A magnesium hot water supply device for supplying molten magnesium stored in a melting furnace through a hot water supply pipe communicating with the outside, wherein the hot water supply pipe is made of a conductive metal and is provided on the outer periphery of the hot water supply pipe. In addition to winding the conductor of the covered wire in a spiral shape, it receives a detection signal from a transformer that converts the AC voltage to a low voltage, a program setting device that sets the disconnection of energization, and a temperature sensor that is installed on the outer surface of the hot water supply pipe. And a temperature indicator controller and a controller connected to the program setter, and magnesium equipped with a heating device for a hot water supply pipe that conducts low-frequency high-current low-frequency induction heating by energizing the conductor. Water heater.