JPH08117947A - Method for heating and transporting half molten metal - Google Patents

Abstract

PURPOSE: To improve a heat retaining property and moldability in a method for heating and transporting half molten metal which heats a metallic blank to a half molten state, then maintaining the blank in this temp. state as far as possible and supplying the blank to a post stage for a die casting sleeve, etc. CONSTITUTION: The metallic blank M in a solid phase state is housed into a ceramic vessel 7 freely attachably and detachably installed on a stand 5 which is freely movable forward, backward, upward and downward. This vessel 7 is positioned in the central part at the axial center of an induction heating coil 12. The vessel 7 is heated for the required period of time to make the metallic blank M into the half molten state; thereafter, the stand 5 is moved and the vessel 7 is clamped and tilted to pour the half molten metal into the die casting sleeve 20.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for heating / conveying a semi-molten metal in which a metal material is heated in a semi-molten state, transferred to a predetermined die cast sleeve and poured.

[0002]

2. Description of the Related Art The thixocasting method has the advantages of less casting defects and segregation than conventional casting methods, a uniform metallographic structure, a long mold life, and a short molding cycle.
This is a technology that has been drawing attention recently. This method is characterized in that a metal material heated to a semi-molten state is injection-molded in a mold cavity, and there is a constraint that an appropriate temperature range is extremely narrow in consideration of product quality and moldability. In many cases, temperature control needs to be controlled within plus or minus 3 ° C. Regarding the transportation of metal material after it has been heated to a semi-molten state, (a) grasp the metal material directly with a robot for transportation. And transfer to a predetermined position. (B) It is conveyed by a jig that is previously heated by another heater. For example, detailed consideration is required to prevent temperature drop.

[0003]

However, (a)
This method has the drawback that the temperature of the metal material tends to drop during transportation and stable molding cannot be performed.Also, even if the amount of liquid phase is small, the strength of the heating material is low. When doing so, there is a problem that a defect occurs or the gripped portion and the portion below it are separated. Further, in the case of a material having a high proportion of liquid phase at the molding temperature, the strength of the metal material itself is low, the shape at room temperature cannot be maintained, and it is impossible from the beginning to grab it with a robot. On the other hand, in the method of (b), it is necessary to preheat the jig with another heater in advance, which is not only complicated but also the operating cost is high.

[0004]

In order to solve the above-mentioned problems, in the present invention, a container made of ceramics is detachably installed on a pedestal which can move back and forth and can move up and down. After accommodating the metallic material in a phase state, positioning the container at the center of the axial center of the induction heating coil, and energizing the induction heating coil for a required time to semi-melt the metallic material in the container, The gantry was moved to grip and tilt the container to pour the metal material in the container into the die-cast sleeve. According to the second aspect of the present invention, a solid-state metal material is housed in a ceramics container that is detachably installed on a platform that can be moved back and forth, moved up and down, and tilted. The metal material in the container is moved and tilted after the metal material in the container is semi-molten by energizing the induction heating coil for a required time while being positioned in the center of the shaft core of The structure was such that the molten metal was poured into the die-cast sleeve. Furthermore, in the third invention, when the metal material is heated by using the induction heating coil, an inert gas for preventing oxidation is injected into the container that houses the metal material. Further, in the fourth invention,
The induction heating method was low-frequency high-current low-frequency induction heating.

[0005]

In the present invention, the metal material in the solid state is housed in the container on the pedestal and is placed in the central portion of the axis of the induction heating coil, and then heated for a required time until it becomes a semi-molten state. The gantry is moved and the gantry is tilted as it is, or the container on the gantry is held by another means and tilted, and the metal material in the container is poured into the die-cast sleeve. In the case of a metal material that easily oxidizes, heating work using an induction heating coil by flowing inert gas, SF ₆ gas, or a mixed gas of SF ₆ gas and CO ₂ gas into the container to prevent oxidation. Prevents the oxidation of the semi-molten metal inside. Also,
Since the induction heating is low frequency induction heating with low voltage and high current,
It is safe without the risk of electric shock death and the equipment cost and power consumption are reduced.

[0006]

Embodiments of the present invention will be described below in detail with reference to the drawings. 1 to 4 relate to an embodiment of the present invention, FIG. 1 is an overall configuration diagram of a heating / transporting robot, FIG. 2 is an explanatory diagram showing the principle of induction heating, and FIG. 3 is an explanatory diagram of a heating / transporting process of a metal material. FIG. 4 is a vertical cross-sectional view of a container for injecting an inert gas. FIG. 1 shows a heating / transporting robot 100 used in the present invention, which comprises an air cylinder 4 mounted on a trolley 3 having wheels 2 reciprocally movable on two parallel traveling rails 1. A pedestal 5 that can be raised and lowered is erected. A rotatable plate 5A, which is rotatable via a pin joint 5a, is arranged on the gantry 5, and is tiltably held by an air cylinder 5B. A ceramic container 7 is placed on the frame 5 and a spring 6a is interposed therebetween. A holding mechanism 6 for holding the container 7 is provided on the upper surface of the rotary plate 5A, and the container 7 is detachably attached. The metal material M is stored in the container 7 attached to the rotary plate 5A, and the container 7 is preliminarily moved by the lateral movement of the carriage 3 traveling and the upward movement of the piston rod 4a of the air cylinder 4 to raise the container 7. The induction heating coil 10 is installed in a predetermined position in the induction heating device 10 having a spiral induction heating coil 12 with a vertical axis.
It is heated by induction heating by energizing 2 to be in a semi-molten state at a predetermined temperature.

FIG. 2 shows the principle of induction heating. When an alternating current is passed through the induction heating coil 12 connected to the AC power source B, an alternating magnetic field D is generated in the object C to be heated. Then, an eddy current E due to an electromagnetic induction action is induced in the object to be heated. 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 this eddy current E is related to the frequency of the current passed through the induction heating coil 12. 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., and normally a 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 induction 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 preparing 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, high-frequency heating may be used in consideration of the fact that the temperature of the molten aluminum or the molten magnesium, which is a metal material often used in the present invention, is 700 ° C., which is a relatively low temperature. In conventional high frequency heating, low frequency induction heating that does not require water cooling, which is indispensable as a measure against thermal burnout of the induction heating coil, is adopted, and the induction heating coil is stopped from being a copper pipe that is difficult to bend, and it is usually marketed. We decided to use a flexible covered electric wire as an induction heating coil. Therefore, the adopted frequency is 50Hz
Alternatively, the normal commercial frequency of 60 Hz is used. Working voltage is 1
The AC power source 40 of 00V is dropped to 25V by the transformer 50, and the value of the current flowing through the conducting wire is about 360A. In the induction heating device 10 of the present invention which employs low frequency heating by such a low voltage and high current, the temperature of the induction heating coil 12 is relatively low at about 60 to 80 ° C. and is the object to be heated. The metal material M can be heated and heated up to about 600 to 750 ° C.

The container 7 in which the metal material M which has been heated in this way and is in a semi-molten state is accommodated therein is lowered from the inside of the induction heating coil 12 and is moved laterally as shown in the process procedure of FIG. After moving and returning to the position of FIG. 1, the rotary plate 5A is tilted by the operation of the air cylinder 5B, and the metal material M is transferred into the tilted die-cast sleeve 20 shown in the figure, whereby a series of Finish the heating / transporting process. In the embodiment shown in FIG. 1, the container 7 is laterally moved, raised, heated, lowered, laterally moved and tilted by the power means of the gantry 5 provided on the carriage 3 (that is, the air cylinder 4, the air cylinder 5B, etc.). However, among these, the tilting of the container 7 may be performed by a tilting mechanism having a separately provided gripping means for the container 7. Also,
In the embodiment of FIG. 1, the container 7 is arranged with the axis centered in the vertical direction, but it is also possible to dispose the container 7 with the axis sideways. In this case, it is convenient that the axial center direction of the induction heating coil 12 of the induction heating device 10 is also horizontal.

FIG. 4 shows a semi-molten state during or after heating.
In order to prevent oxidation of the metal material M of
A lid 7A that can be rotated is provided, and the inert gas injection pipe 8 is attached to the lid 7A.
Attached to the container 7 so that an inert gas can be injected into the container 7.
It is a thing. N as an inert gas₂Gas, CO₂Moth
Gas, Ar gas or SF₆Gas or SF₆Gas and CO ₂
A mixed gas of gases can be used. Also, induction heating device
Reference numeral 10 denotes a temperature sensor (not shown) provided on the inner wall of the container 7.
The temperature of the metal material M measured by
The controller should turn on so that the temperature (for example 700 ° C) is reached.
Automatic control for ON-OFF control of power supply interruption
It is convenient to do so. In addition, the induction heating coil 12
Uses a conventional induction heating coil copper tube for high-frequency induction heating
Do not use a commercially available insulated wire as a conductor.
If you use it, you can directly connect it to the hot water supply pipe
Since it can be wound manually, it is very easy to install.
You. Also, the induction heating coil 12 uses a conductive wire instead of a copper tube.
Then, since it is a covered electric wire, it is safe and workers should pass it.
Even if it comes into contact with a bare wire during electricity
The current value flowing through the human body is approximately 12 mA (human body resistance value 21
00 ohms) and lethal electric shock (50 mA for 3 seconds)
Since it is below, there is little risk of electrocution, so safety is high.
Also, since we did not need expensive equipment such as a frequency switch,
Equipment costs are small.

The container 7 is made of ceramics such as alumina. The reason why the container 7 is made of ceramics is
Only the metal material M in the container 7 is heated by induction heating,
Moreover, the container 7 whose temperature has been raised by the heat has a good heat retaining property during transportation. The material of the container 7 is not limited to alumina, and any ceramic material may be used as long as it does not react with metal or is difficult to store or discharge.

Table 1 is a comparison of the transportability and formability by the method of the present invention compared with the conventional example, using various alloys as metal materials, and actually heating / transporting and forming.

[0013]

[Table 1]

According to Table 1, in the example of the present invention, the temperature just after heating and the temperature just before inserting the sleeve are almost the same, so that the moldability is good. Further, since it is contained in the container, it is easy to carry regardless of the form and strength of the material. On the other hand, in the case of being left in the atmosphere during transportation, in the comparative example, No. Except for 10, the temperature drop is large and the liquid phase rate is low, so the moldability is poor. In addition, No. In the No. 10 alloy, since the liquid phase amount at the eutectic temperature is large, it is difficult to convey. No. 6, No. 7, No. In No. 9, the strength of the material is weak and the conveyance is somewhat difficult. From the results in Table 1, it can be seen that the method of the present invention has good heat retention of the temperature of the semi-molten metal, and accordingly the moldability is improved accordingly.

[0015]

As is apparent from the above description, in the method for heating and transporting a semi-molten metal according to the present invention, it is possible to move a metal material in a solid state up and down, and if necessary, horizontally and rotationally. Insert it into a ceramic container installed on a pedestal, insert the pedestal into the center of the induction heating coil from below, and raise the container to a position where the upper end of the material does not exceed the upper end of the coil. After heating the material in the container to a semi-molten state for a period of time, the cradle is lowered or lifted to tilt the container on the cradle, which is outside the coil, on the sleeve, and the material in the container is tilted. By inserting into a slanted die-cast sleeve, a semi-molten molded product of high quality can be obtained more easily than in the conventional method. Also,
When low-frequency high-current low-frequency induction heating is used, the safety of electric shock accidents is higher than before, the heating coil (covered wire) construction is simple, and the equipment cost is low and the power consumption is low. The consumption is also reduced.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a heating / transporting robot 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 explanatory view of a heating / conveying step of the metal material according to the embodiment of the present invention.

FIG. 4 is a vertical sectional view of a container for injecting an inert gas according to an embodiment of the present invention.

[Explanation of symbols]

 1 Running Rail 2 Wheels 3 Bogie 4 Air Cylinder 4a Piston Rod 5 Stand 5A Rotating Plate 5B Air Cylinder 5a Pin Joint 6 Grasping Mechanism 7 Container 7A Lid 8 Inert Gas Injection Pipe 10 Induction Heating Device 12 Induction Heating Coil (Heating Coil) 20 Die-cast sleeve 22 Plunger

Claims (4)

[Claims] 1. A solid-state metal material is housed in a ceramic container that is detachably installed on a pedestal that can move back and forth and that can move up and down, and the container is a shaft of an induction heating coil. After being positioned in the center of the core, the induction heating coil is energized to turn the metal material in the container into a semi-molten state, and then the gantry is moved to grip and tilt the container to move the inside of the container. A method for heating and transporting semi-molten metal by pouring metal material into the die-cast sleeve. 2. A metal core in a solid state is housed in a ceramics container which is detachably installed on a pedestal that can be moved back and forth, vertically moved, and tilted, and the shaft core of the induction heating coil is stored. After being positioned at the center, the induction heating coil is energized to turn the metal material in the container into a semi-molten state, and then the gantry is moved and tilted to die-cast the metal material in the container. A method for heating and transporting semi-molten metal that is poured into the interior. 3. The semi-molten metal according to claim 1, wherein when the metal material is heated by using an induction heating coil, an inert gas for preventing oxidation is injected into a container for containing the metal material. Heating / transporting method. 4. The method of heating / conveying a semi-molten metal according to claim 1, wherein the induction heating method is low-frequency high-current low-frequency induction heating.