JP3145142B2 - Ingot dissolution method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for dissolving an ingot, and more particularly to a method suitable for dissolving an ingot made of a metal material such as titanium or a titanium alloy having a very high temperature activity.

[0002]

2. Description of the Related Art In melting metals, a crucible made of calcium oxide, yttrium oxide or the like is usually used. Specifically, an ingot of a metal material is put into a crucible, heated and melted by a burner or the like, and the molten metal in the crucible is cast into a mold.

[0003]

However, when a metal material ingot is melted using a crucible, a problem occurs in that the crucible and the metal material react with each other to oxidize the metal material.

Further, the ingot cannot be heated uniformly, and a temperature difference occurs in the molten metal. That is, the temperature of the molten metal portion in contact with the crucible is high, the temperature of the central portion of the upper surface of the molten metal is low, and it is not possible to obtain a molten metal having a uniform temperature.

[0005] Under such circumstances, the structure of the cast product becomes non-uniform, and the quality is actually deteriorated.
In particular, when a material such as titanium or a titanium alloy having a very high temperature activity is melted and precision casting is performed, the quality of a precision casting product is remarkably deteriorated due to a very active reaction.

SUMMARY OF THE INVENTION The present invention has been made in view of such circumstances, and has as its object to provide an ingot in a state of being floated in the air so as not to react with other members. Accordingly, it is an object of the present invention to provide a method of melting an ingot that can perform melting by high-frequency induction heating and can uniformly heat the ingot without causing a temperature difference in the molten metal.

In order to achieve the above object, the present invention provides: (A) a high-frequency induction heating coil having a spiral shape so as to surround an outer periphery of a metal cylindrical body having a plurality of slits extending radially in a radial direction; Along with disposing, the axis of the cylindrical body and the high-frequency induction heating coil are arranged in the vertical direction,
And an upper portion of the cylindrical body is connected to the high-frequency induction heating coil.
So that it protrudes above the topmost winding
And the center of the ingot is the high-frequency induction heating coil.
Arranging the ingot so as to be located above a center height position ; and (B) supplying a required high-frequency current to the high-frequency induction heating coil to cause an electromagnetic force to act on the ingot , thereby causing the ingot to operate. Is the upper end surface of the cylindrical body
And the lowermost part is inside the hollow part of the cylindrical body.
Place the ingot at a height such that it is located at
Because the steps levitated in the air, to the ingot under this state until dissolved immediately before temperature uniformly high-frequency induction heating (preheating) while the ingot caused the rotation in the upper portion of the cylindrical body, (C A) lowering the high-frequency current supplied to the high-frequency induction heating coil to lower the high-frequency induction-heated ingot into the hollow portion of the upper portion of the cylindrical body so as to lower the upper end surface of the cylindrical body and the high-frequency induction heating coil; Levitate in the space area between the uppermost turn of the
Accordingly, a step of floating and melting the ingot, whose rotation has been stopped, by the high-frequency induction heating coil to obtain a spherical molten metal is sequentially performed.

[0008]

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows an apparatus for carrying out a melting method according to the present invention, which shows a floating and melting apparatus 2 for an ingot 1 made of a metal material such as a titanium alloy. The apparatus 2 includes a copper cylindrical body 3 for accommodating the ingot 1 in the internal space, a spiral high-frequency induction heating coil 4 arranged to surround the outer periphery of the cylindrical body 3,
And a high-frequency power supply 5 for supplying a high-frequency current (power) to the power supply.

The above-mentioned cylindrical body 3 has a plurality of slits 7 extending radially in the radial direction, as shown in FIG. At the lower end of the cylindrical body 3, the segments 3a are connected to each other. A cooling water passage 3b is formed inside each segment 3a, and one end of the cooling water passage 3b is connected to the water pipe 8 and the other end is connected to the drain pipe 9. On the other hand, the high-frequency induction heating coil 4
Similarly, the cooling water is supplied to the hollow portion to cool the coil 4 itself.

As shown in FIG. 1, the cylindrical portion 3 and the high-frequency induction heating coil 4 are arranged coaxially with each other, and their axes are arranged along a vertical direction (up-down direction) . The upper portion 3c of the cylindrical portion 3 is arranged so as to protrude above the uppermost winding portion 4a of the high-frequency induction heating coil 4.

On the other hand, a mold 11 having a molding cavity 10 is arranged below the flotation melting apparatus 2, that is, below the hollow portion of the cylindrical body 3 (see FIG. 1). ).

Next, the ingot 1 is
The operation and action at the time of dissolving is described.

First, a columnar ingot 1 as shown in FIG. 3 is placed on a ceramic mounting table (not shown), and the mounting table is raised, whereby the ingot 1 is transferred into the hollow portion of the cylindrical body 3 and the high frequency the center height H ₁ of the induction heating coil 4 disposed above (see FIGS. 1 and 4). Then, a required high-frequency current is supplied from the high-frequency power supply 5 to the coil 4, whereby the ingot 1 is levitated in the air as shown in FIG.

Here, the principle of levitating the ingot 1 will be briefly described as follows. That is, as the high-frequency current J ₀ flows through the high-frequency induction heating coil 4 in the direction indicated by the arrow in FIG. 1, the magnetic flux φ is generated around the axis of the cylindrical body 3 by the high-frequency current J ₀ . The magnetic flux φ penetrates and acts on the ingot, and a high-frequency induced current _Je flows on the surface of the ingot 1 in the illustrated direction. The high frequency induction current J _e heats the surface of the ingot 1 with Joule heating.

On the other hand, an electromagnetic force F is generated on the surface of the ingot 1 due to the interaction between the induced current J _e flowing on the surface of the ingot 1 and a magnetic flux near the surface (magnetic flux having a magnetic flux density B). This electromagnetic force F is proportional to the product of the induced current _Je and the magnetic flux density B, and its direction is the direction indicated by the arrow in FIG. 1 according to Fleming's left-hand rule.

[0017] The electromagnetic force F, the force F _c towards the axis of the cylindrical body 3, is a component force in a force F _u to levitate ingot 1. The buoyancy force _Fu is generated over the entire surface of the ingot 1 and levitates the ingot 1.
As a result, the ingot 1 is ideally heated in a non-contact state with other members while being levitated in the air.

In this case, the cylindrical ingot 1
As shown in FIG. 4, the circular end faces 1a, 1b are directed toward the inner peripheral surface side of the cylindrical body 3, and these circular end faces 1a, 1b are
The opposite ends 1c and 1d of 1b are arranged on the same horizontal line. That is, the longest portion L (see FIG. 3) of the ingot 1 is arranged horizontally.

Further, in the present embodiment, levitation heating is performed in a state where the ingot 1 is rotated by electromagnetic force. That is, when the height position of the ingot 1 with respect to the cylindrical body 3 is adjusted by adjusting the magnitude of the high-frequency current supplied to the high-frequency induction heating coil 4, the ingot 1 rotates around the horizontal axis N. Specifically, the center O (or the horizontal axis N ingot 1) of the ingot 1 by allowed to increase the high-frequency current is arranged above the upper end surface position of H ₂ cylinder 3 as shown in FIG. 5, and When the lowermost end portion P of the ingot 1 is disposed in the hollow portion of the cylindrical body 3, the ingot 1 rotates around the horizontal axis N.

It is presumed that such rotation is caused by the following operation. That is, ingot 1
Receives the largest electromagnetic force from the uppermost winding portion of the high-frequency induction heating coil 3. The high-frequency induction heating coil 3 has a spiral shape, and the uppermost winding portion 4a is inclined with respect to the horizontal plane. ing. Therefore, the induced current flowing on the surface of the ingot 1 adjacent to the uppermost side of the winding part 4a and the magnetic flux density acting on the surface are different from the surface on the opposite side (corresponding to the lowermost part of the winding part). (The surface of the ingot 1), so that the electromagnetic force generated on said surface is always greater than on the opposite surface. Such a force relationship affects the lower portion of the ingot 1 in the hollow portion of the cylindrical body 3, and a force in one direction acts on the ingot 1 as a rotational force. As a result, ingot 1
Is uniformly heated by high-frequency induction while being rotated about its horizontal axis N.

[0021] Incidentally, when the center O of the ingot 1 is below the upper end surface position of H ₂ cylinder 3, an electromagnetic force in one direction to a portion of the ingot 1 in the hollow portion of the cylindrical body 3 acts Also, no rotation about the horizontal axis N occurs. This is presumed to be due to the holding force acting to levitate and hold the ingot 1 in the hollow portion of the cylindrical body 3. Further, when levitate lowest point of the ingot 1 above said upper end surface position H _2, but the ingot 1 is thus spilled from the cylindrical body 3 without levitation state is maintained, which is of the cylindrical body 3 It is presumed that this is because the magnetic flux in the outside cannot be held at a position above the cylindrical body 3 because it is not uniform.

Thus, when the ingot 1 is subjected to high-frequency induction heating in a state of being levitated and rotated, the ingot 1 is heated.
Is heated uniformly. Ingot 1 is rotated like this
The reason for uniform heating is as follows
This is to obtain the effect. That is, a cylinder, a rectangular parallelepiped,
Levitate an ingot in the shape of a cube, etc. in the usual way
In the case of high-frequency induction heating, (a) the corner of the ingot 1
It is placed closest to the inner circumferential surface, resulting extremely intensive magnetic flux at the corners of the (b) ingots 1
Due to the two phenomena, only the corner of ingot 1
Is heated and melted, and the melted part is
Like spilling from other parts that are not heated
It will be a defect. However, as in the present invention,
Rotate the ingot to rotate each of the ingots under that condition.
Part is preheated uniformly, and then the main heating is applied
In this way, the problems described above can be eliminated.
You.

After uniformly heating the ingot 1 to the temperature immediately before melting, the high-frequency current supplied to the high-frequency induction heating coil 4 is reduced to a predetermined value. As a result, the electromagnetic force acting on the ingot 1 is weakened, so that the ingot 1 is lowered vertically downward and floats in the hollow portion of the upper portion 3c of the cylindrical body 3 as shown in FIG.

Further, when the high-frequency induction heating is continued under the floating state, the ingot 1 reaches a predetermined melting temperature and starts to melt from its surface portion. When the molten metal is completely melted to the inside of the ingot 1, the molten metal tends to have a minimum volume due to its surface tension. As a result, the molten metal remains in a floating state in the hollow portion above the cylindrical portion 3 as shown in FIG. It becomes a spherical molten metal 1 '.

Thereafter, when the molten metal 1 'reaches the required casting temperature, the supply of the high-frequency current to the high-frequency induction heating coil 4 is stopped. As a result, the electromagnetic force acting on the ingot 1 disappears, so that the molten metal 1 ′ falls naturally under its own weight and is cast into the molding cavity 10 of the mold 11.

Floating and melting apparatus 2 for ingot 1 as described above
According to this, since the ingot 1 can be melted in a non-contact state with other members, the molten metal 1 'of the ingot 1 is ideally heated and melted without causing a reaction. Moreover, the cylindrical body 3
The ingot 1 is uniformly preheated to a temperature just before melting under a floating / rotating state at a position above the ingot, so that the melting of the ingot 1 in the hollow portion of the upper portion 3c of the cylindrical body 3 is caused by temperature It will be performed in a very short time without any difference. Therefore, the molten metal is cast into the mold 1 without causing a reaction and without causing a temperature difference.
1, and a cast product having a uniform structure and good quality can be obtained.

The embodiment of the present invention has been described above.
The present invention is not limited to the embodiments described above, and various modifications and changes can be made based on the technical idea of the present invention. For example, the shape of the ingot 1 to be melted need not be a cylinder, but may be a square pillar, a cube, or a rectangular parallelepiped. The material of the ingot 1 is not limited to titanium or a titanium alloy, but may be iron, steel, stainless steel, aluminum, or the like. In addition, cylindrical body 3
After melting the ingot 1 of various shapes in the hollow portion of the upper part 3c, the high-frequency current supplied to the high-frequency induction heating coil 4 is gradually reduced to solidify the molten metal 1 'to obtain a spherical ingot. Good.

[0028]

As above, according to the present invention, the present invention is, after uniformly high-frequency induction heating until dissolution temperature immediately before the ingot levitation-rotation state at the upper end portion of the cylindrical body with a slit, high frequency
To reduce the high-frequency current supplied to the wave induction heating coil.
With this, the ingot is lowered into the hollow portion of the upper portion of the cylindrical body and heated and melted , thereby obtaining a spherical molten metal . Therefore, the ingot can be melted without reaction by levitation heating. At the same time, a molten metal having no partial temperature difference in the molten metal can be obtained. As a result, it is possible to prevent non-uniformity in the structure of the cast product obtained from the above-described molten metal, and to manufacture a high-quality cast product.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing a flotation melting apparatus for performing an ingot melting method according to the present invention.

FIG. 2 is a plan view of the device.

FIG. 3 is a perspective view of an ingot to be melted.

FIG. 4 is a cross-sectional view showing a state where an ingot is levitated in a hollow portion of a cylindrical body.

FIG. 5 Floats the ingot at a position above the cylindrical body.
It is sectional drawing which shows the situation heating in a rotation state.

FIG. 6 shows a preheated ingot placed on the upper part 3 of the cylindrical body.
It is sectional drawing which shows the state which descended in the hollow part of c.

FIG. 7 is a sectional view showing a state in which an ingot is heated and melted in a hollow portion of the upper portion 3c to obtain a spherical molten metal.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ingot 1 'Molten metal 2 Floating and melting apparatus 3 Cylindrical body 3c Upper part 4 High frequency induction heating coil 4a Uppermost winding part 7 Slit N Horizontal axis L Longest part

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C22B 1/00-61/00 F27B 14/06 F27D 11/06 H05B 6/32

Claims (1)

(57) [Claims] (A) A spiral high-frequency induction heating coil is provided so as to surround the outer periphery of a metal cylinder having a plurality of slits extending radially in the radial direction, The axis of the induction heating coil is arranged in the vertical direction, and the upper part of the cylindrical
Project above the topmost winding of the wave induction heating coil
So that the center of the ingot is the high frequency induction
Arranging the ingot so as to be located above the center height position of the heating coil; and (B) supplying a required high-frequency current to the high-frequency induction heating coil to apply an electromagnetic force to the ingot. By acting, the center of the ingot is closer to the upper end face of the cylindrical body.
And the lowermost part is inside the hollow part of the cylindrical body.
Place the ingot at a height such that it is located at
Because the steps of levitated in the air, to uniformly high-frequency induction heating the ingot up to the solubility immediately before the temperature under the state in the state of the ingot caused the rotation in the upper portion of the cylindrical body, (C) the high-frequency By reducing the high-frequency current supplied to the induction heating coil, the high-frequency induction-heated ingot is lowered into the hollow portion of the upper portion of the cylindrical body, and the upper end surface of the cylindrical body and the uppermost end of the high-frequency induction heating coil Levitate in the space area between the side turns,
A step of floating and melting the ingot, whose rotation has been stopped, with the high-frequency induction heating coil to obtain a spherical molten metal, sequentially performing a method of melting the ingot.