JPH116016A - Induction heating device for aluminum billet and die casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a device which accurately heats an aluminum billet supplied into a die casting machine to a prescribed temp. SOLUTION: Plural coils C1 ... are arranged in series and horizontal state and gaps K1 ... restraining magnetic interference, the formed among these coils, and an electric power frequency adjusting device for supplying into individual coil or in each set of plural pieces of coils, is arranged and rails 3 are arranged so as to horizontally support a tray 4 in the longitudinal direction and in the crossing direction of the coils. The supplied aluminum billet W is made to lay in the horizontal direction on the tray 4 under no roll-moving condition and further, a shifting device for shifting the trays 4 supporting the aluminum billet W in the series state, is arranged.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for induction heating an aluminum billet to be supplied to an aluminum die casting step and the like, and a die casting apparatus subsequent to the induction heating apparatus.

[0002]

2. Description of the Related Art Among various die-casting products, aluminum die-casting products are widely used because of high accuracy and high productivity, especially for automobile parts, in order to reduce the weight. When the molten aluminum alloy is supplied to the die casting machine in this die casting process, air and gas are entrained while moving in the mold, and pinholes are generated by the gas released from the molten aluminum itself, As a result, there is a problem that the strength of the product is reduced. Therefore, in this casting process, it is a problem how to release the gas. For this purpose, a method in which the pressure in the mold is reduced to release the gas is generally adopted.

[0003] When a molten aluminum alloy is cast as described above, there is an essential disadvantage that the strength of the product is reduced by sucking gas. Therefore, a semi-solid molding method for supplying an aluminum billet in a semi-molten state to a die casting machine has been proposed in order to prevent this drawback.

In this semi-solid molding method, an aluminum billet having a dendrite structure adjusted to a specific state is heated to a semi-molten state and supplied to a die-casting machine. The aluminum in the state flows in a laminar flow state, so that the flow between the layers is restricted, and the entrainment of gas is substantially prevented as compared with the die casting step in which the aluminum is pressed into the mold in a molten state as described above. It is possible to increase the strength of the product.

[0005] In order to use the aluminum semi-solid molding method, a casting material having an outer peripheral portion having a dadelite on the outer periphery of a main portion is used, and heating is performed to a semi-molten state in which a solid phase and a liquid phase coexist. A method of converting the dendrite into a spherical solid phase by raising the temperature of the outer peripheral portion preferentially over the main portion, specifically adopting a primary and secondary induction heating step, wherein the frequency of the primary induction heating step is Has been proposed in Japanese Patent Application Laid-Open No. 8-157975.

Further, a coil is wound around the outer periphery of the cylindrical heating chamber,
Furthermore, a slide rail is laid on the bottom of this cylindrical heating chamber,
An apparatus in which a receiving tray is extended to the slide rail at an outlet portion and is disposed so as to be able to be separated from and contacted by a driving means is disclosed in Japanese Patent Application Laid-Open No. Hei 8-
No. 85826.

[0007]

The method of die-casting an aluminum alloy in a semi-molten state is effective for improving the strength and quality of a cast product by casting while preventing the occurrence of pinholes in the cast product. It is a way.

However, the method of heating a casting material described in Japanese Patent Application Laid-Open No. 8-157975 has a problem that the heating time must be separately three minutes in the first stage and four minutes in the second stage. Further, in order to put this method to practical use, the problem that the mechanism for inserting and discharging the aluminum billet into and from the coil must be complicated.

Further, the billet induction heating apparatus for semi-solid processing proposed in Japanese Patent Application Laid-Open No. 8-85826 uses a single coil, so that a slight change in temperature causes slight changes in the temperature of aluminum billets, especially Since the state of the solid phase and the state of the liquid layer change, there is an essential problem that the heating control at a low temperature and in the semi-molten state cannot be separated for the aluminum billet.

In addition, a billet induction heating device for semi-molten processing proposed in Japanese Patent Application Laid-Open No. 8-12771 is arranged such that one coil is disposed horizontally and a billet moving in the coil is heated while rotating. ing. When the billet is rotated in the heating step in this way, the internal structure of the molten metal at the time of reheating, particularly the size of dendrites, changes, and the metal structure in a semi-molten state is destroyed. Further, it is extremely difficult to accurately control the temperature of the aluminum billet having delicate characteristics by electromagnetic induction heating using one coil as described above.

According to experiments conducted by many of the present inventors, upon reheating of an aluminum billet having thixotropic properties, a semi-molten state, for example, a solid phase of about 2 just before melting of aluminum.
In the case of 0 to 60%, when the molten metal in the aluminum billet is stirred by an electromagnetic force as an external force, the dendrite in the solid phase of the internal structure is destroyed and the crystal structure changes. As described above, in a die casting machine, it is necessary to inject aluminum into a mold in an appropriate laminar flow state, but it is difficult to obtain an appropriate laminar flow state during casting in this state.

On the other hand, in the induction heating of the aluminum billet, in a low frequency region of 1000 Hz or less, the depth of penetration of the induced current is large, so that the soaking effect is large. However, in this frequency range, a strong electromagnetic stirring force is generated, which makes it difficult to destroy the crystal structure in the aluminum billet and heat the billet to a semi-molten state.

The higher the frequency, the smaller the electromagnetic stirring force, but the shallower the depth of the induced current. Therefore, by setting the latter half frequency higher than the first half frequency in which the billet is heated to the semi-molten state, it becomes possible to perform heating with good heat uniformity and without breaking the crystal structure. By setting the frequency to several hundreds Hz in the rapid heating part, and adopting a frequency three to four times thereafter, the influence of mutual interference of the coils on the thyristor inverter can be minimized.

For example, in Japanese Unexamined Patent Application Publication No. 8-1271, the coils are arranged horizontally, but a single coil is employed and the work itself is configured to rotate. However, reheating an aluminum billet containing a specific thixotropic dendrite by this method has a problem that an unstable molten metal cannot be supplied into a mold in a laminar flow state.

When a plurality of aluminum billets are heated in a single coil, the heating state greatly changes between a low temperature state and a semi-molten state state. Cannot be heated to exactly the temperature at which

Therefore, the present inventor has conducted induction heating as a pre-process for supplying a semi-molten aluminum alloy into a die of a die-casting machine without breaking as much as possible the solid-state dendrite contained in the semi-molten casting material. It is an object of the present invention to provide an apparatus and a die casting apparatus in which the apparatus is arranged in a preceding stage.

[0017]

Means for Solving the Problems An induction heating apparatus for an aluminum billet according to the present invention for achieving the above object is constituted as follows. 1) An apparatus for induction heating an aluminum billet having a solid phase dendrite structure adjusted to an internal structure, in which a plurality of coils are arranged in series and horizontally, and a gap for suppressing magnetic interference is provided between the coils. A frequency adjusting device is provided for adjusting the frequency of power to be supplied to the individual coil or the set of the plurality of coils, and a tray is supported inside the coil horizontally in the transverse direction and the longitudinal direction of the coil. The aluminum billet to be supplied is arranged so that the supplied aluminum billet is not affected by the electromagnetic force and is laterally placed on the fire-resistant tray without rolling. A transfer device is provided for moving the tray supporting the aluminum billet in series.

2) The plurality of coils are divided into at least a first stage and a second stage, and a low frequency power is supplied to the first stage coil and a higher frequency power is supplied to the second stage coil. It is configured. 3) The frequency of the preceding coil is several hundred Hz,
Further, the frequency of the latter coil is set to be several thousand Hz.

4) The aluminum billet to be induction-heated is
After reheating, a material having thixotropic properties is used as a casting material. 5) The tray on which the aluminum billet is to be placed is made of a non-magnetic refractory such as silicate-based heat-resistant material, mica ceramics, or alumina-based porcelain. A guide member having a guide surface in the longitudinal direction of the bottom surface is provided. A concave portion for supporting the aluminum billet in a horizontal direction is provided, and a grip portion of a robot arm is provided on a side surface.

6) The heating rate of the aluminum billet in the preceding stage is as follows:
5 to 10 ° C./sec, and the subsequent heating rate is 0.5 to 1.0 ° C./sec.
Each is adjusted to seconds. 7) In the die casting apparatus of the present invention, a plurality of coils are arranged in series and horizontally in order to induction heat an aluminum billet having a solid phase dendrite structure adjusted to the internal structure, and magnetic interference is generated between the coils. A frequency adjusting device is provided for forming a gap for suppressing the power supply and adjusting the frequency of electric power supplied to the individual coil or the set of the plurality of coils, and a tray is provided inside the coil in a transverse direction and a longitudinal direction of the coil. The rails are arranged so that they are supported horizontally, and the supplied aluminum billet has the property of being unaffected by electromagnetic force and is placed sideways on a fire-resistant tray without rolling. An aluminum billet induction heating device further provided with a transfer device for moving the tray supporting the aluminum billet in series, and the induction heating device A device to load the aluminum billet into the die-casting machine from the final coil while being placed on the tray, a device to return the empty tray to the front side of the first coil, and a mechanism to supply the aluminum billet and place it on the center of the tray It is composed of

8) An engaging portion for engaging with a robot hand is provided on a side surface of the tray, and the robot hand is engaged with the engaging portion to receive an aluminum billet on the tray and load the aluminum billet into a die casting machine. During this time, a device is provided to hold the aluminum billet horizontally.

[0022]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a side view of an induction heating device 1A for an aluminum billet. An aluminum billet preparation / supply unit 2 for cutting an aluminum rod and supplying the same to the induction heating coil unit 1 is disposed at the front of the induction heating coil unit 1. A guide rail 3 is provided for guiding the aluminum billet supplied from the aluminum billet preparation / supply unit 2 onto a tray from the inlet 1a to the outlet 1b of the induction heating coil unit 1.

The aluminum billet preparation / supply unit 2 includes a guide unit 2b for guiding the aluminum rod B at a lower portion of the frame 2a.
And a cutting machine 20 for cutting this into a predetermined length, and the aluminum billet W obtained by cutting is placed on the tray 4,
A device 2d for supplying the inside of the induction heating coil unit 1 is provided. And the inlet 1a of the induction heating coil unit 1
And stoppers 1c and 1d are provided at the outlet 1b. 2e is an operation panel.

FIG. 2 is a side sectional view of a main part of the induction heating coil unit 1, and FIG. 3 is a front sectional view of the same, showing a first coil C ₁ , a second coil C ₂ , a third coil C ₃ , and a fourth coil. coil C _4, 5
Coil C ₅ and the sixth coil C ₆ are provided horizontally in series centered axis. A gap K ₁ between these coils for preventing the influence of electromagnetic induction of the adjacent coils.
K ₂ , K ₃ , K ₄ , and K ₅ are provided, respectively. The inner circumference of the coil C is protected by a heat-resistant plate Cb.

[0025] The two guide rails 3 for guiding the tray 4 between the inlet 1a and the outlet 1b is extended through said coil C ₁ -C ₆ horizontally. The guide rail 3 is configured to engage with guide portions 4p and 4q provided in parallel with the lower surface of the tray 4.

The guide portion 4p uses a ceramic plate formed in a plate shape as a guide surface, and linearly contacts the arc surface of the top surface of the guide rail 3. The other guide portion 4q has a U-shaped ceramic plate, and is configured to linearly contact two places on the top surface of the guide rail 3 and guide along the guide rail 3 of the tray 4. Have been.

The tray 4 is not electromagnetically affected by non-magnetic refractories such as calcium silicate-based heat-resistant materials, mica-based ceramics, and alumina-based ceramics, and has heat resistance. As shown in FIG. 7, a concave portion 4d for supporting the aluminum billet W is formed on the upper surface, receiving surfaces 4e, 4e formed on the left and right sides of the concave portion 4d, and a peripheral edge portion 4f raised in a dish shape. Concave portions 4g for engaging the arm of the robot are formed on the surface.

The aluminum billet W is a material having a solid-state dendrite structure controlled in the internal structure. Specifically, the aluminum billet W is made into a spheroid by changing the aluminum α phase into the spheroid which receives the least heat. Is a cylindrical material for aluminum casting that can maintain the shape of a billet even in a semi-molten state in which a liquid phase and a liquid phase coexist.
See literature such as 36298.

The aluminum billet W placed on the tray 4 having the above-mentioned structure has various dimensions. For example, an aluminum billet having a diameter of 76.2 mm and a length of 150 to 200 mm is employed. The dimensions of the aluminum billet W are determined from the size of the final product and the capability of the die-casting machine. Further, the winding diameter of the coil C is determined from the dimensions of the tray 4 and the relationship between the guide rail 3 and the heat-resistant plate Cb.

In short, the aluminum billet W is placed on the tray 4.
Is placed in the coil C of the heating induction coil unit 1 in a state where it is placed, the dimensions of each part of the tray 4 are adjusted so that the center line of the aluminum billet W substantially coincides with the center line of the coil C. decide.

FIG. 4 shows stoppers 1c and 1d provided at the entrance 1a and the exit 1b of the heating induction coil unit 1, respectively. When the tray 4w on which the aluminum billet W is placed is supplied, (A) As shown in the figure, the stoppers 1c and 1d are pivoted down and the tray 4 on which the unheated aluminum billet W is placed.
It is assumed that w can move on the rail 3 and be supplied.

Further, 4 ₁ to 4n is heated induction coil 1
The tray 4 supporting the aluminum billet W being accommodated therein and being heated is shown, and 4w is the tray 4 on which the aluminum billet W at the receiving position is placed.

The two stoppers 1 as shown in FIG.
When c and 1d are lowered from the upper surface of the guide rail 3, the trays 4a to 4a on which the aluminum billet W is placed are placed.
n is advanced by the pusher 22 (FIG. 1) by a distance corresponding to one, and a new tray 4w is supplied to the rightmost portion, and the frontmost tray 4a is pushed out from the outlet portion 1b. In this case, it is preferable that the tray 4a is operated so as to advance more than one tray and to keep a distance for the stopper 1d to move.

When the foremost tray 4a on which the aluminum billet W is mounted is sent out as described above, the stoppers 1c and 1d are rotated as shown in FIGS. 4n and 4w are located at predetermined positions in the heating induction coil unit 1, that is, the first to sixth coils C ₁ in FIG.
It is positioned in the middle portion in the longitudinal direction of -C _6. In this state, the aluminum billet W placed on the trays 4b to 4w
Is configured to position in the diametrical direction of the center of the coil C ₁ -C _6, in the longitudinal direction of the intermediate position, it will be supported in a horizontal state.

In the state shown in FIG. 3C, the aluminum billet W can be substantially uniformly induction-heated. After the aluminum billet is induction-heated at a predetermined frequency for a predetermined period of time, As shown in FIG. 1A, one newly heated aluminum billet W is supplied from the inlet 1a.
FIG. 8 is a perspective view showing a series of devices including an aluminum billet cutting device 20, an aluminum billet induction heating device 1A, and a die casting machine 40. The aluminum billet cutting device 20 mounts a large number of aluminum bars B on a gantry 21. Then, the aluminum billets W are cut one by one by the saw-tooth-type cutting machine 20a to the predetermined length to form short aluminum billets W.

The cut billet W rises from the cutting level to the coil entrance level by the lifter 2c,
By rotating the coil by 0 degrees, the direction of the coil entrance coincides with the longitudinal direction of the billet. Then, the aluminum billet W is placed on the tray 4 by the billet supply device 2d, and the supply pusher 2
It is transported to the position 2 and transferred on it. A stopper 1c is located in front of the supply pusher 22.
Induction heating coil unit 1 of aluminum billet induction heating device 1A
At the entrance 1a.

A billet handling robot 30 is provided on the side of the aluminum billet induction heating device 1A.
1 is rotated and moved up and down, and the main body is also turned. The aluminum billet W, which is delivered from the outlet 1b of the heating coil unit 1 and is induction-heated to a predetermined temperature, is
Arm 31 is inserted into recess 4g (FIG. 5) provided on the side of tray 4.
The aluminum billet W heated in a semi-molten state is supplied to the supply port 42 of the plunger sleeve 41 of the die casting machine 40 by being engaged with and gripped by a hand 32 attached to the die casting machine 40. Die casting machine 4
The aluminum billet W supplied to the mold 4 is closed by a plunger that moves inside the plunger sleeve 41.
3 and die-cast.

The tray 4 emptied by supplying the aluminum billet W to the die casting machine 40 as described above
The billet is transferred to the tray cleaning device 50 by 1, where predetermined cleaning is performed, and the billet cutter 20 returns to the position 1 a for receiving the cut billet W.

The apparatus according to the present invention comprises a central portion in the longitudinal direction of the induction heating coil portion 1 in which a plurality of coils are arranged in series as shown in FIG. 2 and a center of the coil shown in FIG. The aluminum billet W is supplied in a state where it is supported with its center aligned, and the coil is energized for induction heating for a predetermined time while maintaining this state.

As shown in FIG. 2, the six coils C _{1 to} C ₆
In the induction heating coil unit 1 composed of
In ₁ -C ₂ and subsequent state coil C ₃ is partitioned into two groups of -C _6, so the power of different frequencies are supplied via the control panel 36 and a thyristor inverter 34, 35 I have.

As one example, the preceding coils C ₁ -C ₂
At a frequency of 530 Hz and a magnetic field strength of about 2200 AT / c
m (ampere-turns / cm) to the coils C ₃ -C
₆ , and about 750 AT / cm at a frequency of 2150 Hz.

As described above, the center of the aluminum billet W is aligned with the center of the induction heating coils C _{1 to} C ₆ as shown in FIG. 3, and at the intermediate position in the longitudinal direction of the induction heating coil as shown in FIG. By energizing both the coils with the aluminum billet W positioned, the aluminum billet W is uniformly heated in two stages to a temperature suitable for die casting, for example, around 570 ° C.

In this heating step, the aluminum billet W
As shown in FIG. 3, the aluminum billet W is kept lying on the tray 4 so as not to roll, so that the aluminum billet W can be deformed even if heated to a temperature just before melting. In addition, as described above, the billet handling robot 30 is supplied to the die casting machine 40 within the turning operation range of the robot 30, and good die casting is performed without gas or air being entrained in the metal layer.

In the induction heating step, the rate of temperature rise of the aluminum billet W of the preceding induction heating coils C ₁ -C ₂ is 5
By heating the aluminum billet W immediately before the stable melting of the tissue by controlling the rate of temperature rise of the induction heating coils C _{3 to} C ₆ in the range of 0.5 to 1.0 ° C./sec.
Then, it can be supplied to the die casting machine 40. Although not shown in detail, the individual induction heating coils C _{1 to} C ₆
In addition, it is also possible to supply power consisting of individual currents at individual frequencies.

In addition, in the induction heating, the temperature uniformity during the heating greatly affects the temperature distribution in the final stage. An electric soaking furnace must be specially added.

To make the temperature at the time of supplying the heated billet to the die casting machine appropriate and uniform,
It is a place that greatly contributes to the properties of the final product, and by designing the coil length and the interval between adjacent coils in each heating step to match the billet length, the induction heating device of the present invention adds an It has been confirmed that there is no need to perform the above, and an extremely excellent effect is exhibited.

Further, by providing the coil with terminals (tap) at an appropriate winding pitch, the actual coil length can be changed without changing the coil itself according to the change in billet length. It can correspond to the length of the billet to be heated. Moreover, even if the diameter of the billet is changed by configuring so that the upper and lower positions of the guide rail 3 with respect to the induction heating coil can be changed,
Precise temperature control can be performed by accurately aligning the center of the billet with the center of the coil.

[0048]

The induction heating apparatus for an aluminum billet according to the present invention is an apparatus for induction-heating an aluminum billet having a solid phase dendrite structure controlled in an internal structure, wherein a plurality of coils are arranged in series and horizontally. A gap for suppressing magnetic interference is formed between the coils, and a frequency adjusting device for adjusting the frequency of electric power supplied to each of the individual coils or a set of a plurality of coils is provided. In this state, the rails are arranged so as to be horizontal in the transverse and longitudinal directions of the coil, and the supplied aluminum billet is not affected by electromagnetic force and does not roll sideways on a fire-resistant tray. The aluminum billet is provided with a transfer device for moving a center position of the coil in a transverse direction and a longitudinal direction of the coil.

Therefore, the aluminum billet can easily perform fine temperature control in the radial direction and the longitudinal direction, and the aluminum billet heated to an accurate temperature can be supplied to the die casting machine. The aluminum billet supplied to the heated die casting machine as described above will flow in a laminar flow in the mold, and the amount of gas and air involved is small, so the structure is uniform and the strength of the die cast product is high. Can be cast.

[Brief description of the drawings]

FIG. 1 is a side view showing an induction heating device and an aluminum billet supply device according to the present invention.

FIG. 2 is a side sectional view showing a relationship between an induction heating coil, a tray, and an aluminum billet.

FIG. 3 is a cross-sectional view showing a relationship with a tray or the like across the honor heating coil shown in FIG. 3;

FIG. 4 is an explanatory diagram showing a relationship between a tray arranged in an induction heating coil and a stopper, and FIG. 4A shows a state before one heated billet is moved, and FIG. () Shows the state immediately after the end of the movement, and FIG. (C) shows the state in which both sides of the aluminum billet arranged in the induction heating coil are fixed by stoppers.

FIG. 5 is a sectional view of a tray.

FIG. 6 is a plan view of the tray of FIG. 5;

FIG. 7 is a side sectional view of the tray of FIG. 5;

FIG. 8 is a perspective view showing the overall arrangement of the apparatus shown in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1A Aluminum billet induction heating device 1 Induction heating coil part 1a Inlet part 1b Outlet part 1c, 1d Stopper 2 Aluminum billet preparation / supply part 2a Frame 2b Guide part 2c Lifter 2d supply device
2e Operation panel 3 Guide rail 4 Tray 4d Recess 4
e Receiving surface 4f Peripheral edge 4g Recess 4p, 4q Guide 20 Aluminum billet cutting device 21 Mount 22
Supply pusher 30 Die casting machine 31 Billet handling robot 50 Tray cleaning device 34, 35 Thyristor inverter

Continued on the front page (72) Inventor Hirokatsu Matsuura 3-1-1, Tamano, Tamano-shi, Okayama Prefecture Mitsui Engineering & Shipbuilding Co., Ltd. (72) Inventor Seiichi Kitamura 3-1-1, Tamano-shi, Tamano-shi, Okayama Mitsui Engineering & Shipbuilding Tamano Office Co., Ltd.

Claims (8)

[Claims] 1. An apparatus for induction heating an aluminum billet having a solid-phase dendrite structure controlled in an internal structure, wherein a plurality of coils are arranged in series and horizontally, and magnetic interference is suppressed between the coils. A frequency adjusting device that adjusts the frequency of the power supplied to each of the individual coils or sets of the plurality of coils is provided, and the inside of the coil is horizontal in the transverse direction and the longitudinal direction of the coil. The rails are arranged so as to support the tray, and the supplied aluminum billet is placed on the tray, which is not affected by electromagnetic force and has fire resistance, in a horizontal direction and does not roll. An induction heating device for an aluminum billet, further comprising a transfer device for moving a tray supporting the aluminum billet in series. 2. The method according to claim 1, wherein the plurality of coils are divided into at least a first stage and a second stage. A low frequency power is supplied to a first stage coil, and a higher frequency power is supplied to a second stage coil. The aluminum billet induction heating device according to claim 1, which is configured. 3. The frequency of the preceding coil is several hundreds of hours.
z, and the frequency of the subsequent coil is several thousand
3. The aluminum billet induction heating device according to claim 2, wherein the frequency is Hz. 4. The aluminum billet induction heating apparatus according to claim 1, wherein the aluminum billet to be subjected to induction heating has thixotropic characteristics after reheating. 5. The tray is made of a non-magnetic refractory such as calcium silicate-based heat-resistant material, mica-based ceramics, or alumina-based porcelain, has a guide portion formed in the longitudinal direction of the bottom surface, and has an aluminum billet in the center of the upper surface. 2. A tray for an induction heating device according to claim 1, wherein a concave portion for supporting the arm is provided, and a grip portion for a robot arm is provided on a side surface. 6. The heating rate of the aluminum billet in the preceding stage is 5 to 5.
2. The induction heating apparatus for an aluminum billet according to claim 1, wherein the heating rate in the subsequent stage is adjusted to 0.5 to 1.0 [deg.] C./sec. 7. An apparatus for induction heating an aluminum billet having a solid-phase dendrite structure adjusted to an internal structure, wherein a plurality of coils are arranged in series and horizontally, and magnetic interference is suppressed between the coils. A frequency adjusting device that adjusts the frequency of electric power supplied to each of the individual coils or sets of the plurality of coils is provided, and the inside of the coil is horizontally arranged in the transverse direction and the longitudinal direction of the coil. The rail is arranged so as to support the tray, and the supplied aluminum billet has a characteristic not affected by electromagnetic force, and is placed on the tray having fire resistance in a horizontal and non-rolling state. And an aluminum billet induction heating device further provided with a transfer device for moving the tray supporting the aluminum billet in series, and a final device of the induction heating device. A device that transfers an aluminum billet from a coil to a tray while loading it on a tray, a device that returns an empty tray to the front side of the first coil, and a mechanism that places the aluminum billet at the center of the tray And a die casting apparatus. 8. An engaging portion for engaging with a robot hand is provided on a side surface of a tray, and the robot hand is engaged with the engaging portion to receive an aluminum billet on the tray and load the aluminum billet into a die casting machine. 8. The die casting apparatus according to claim 7, further comprising a device for horizontally holding the posture of the aluminum billet.