JPH05214459A - Method and device for levitation heating of lump metal - Google Patents

Abstract

PURPOSE:To prevent scattering of molten metal resulted from the rotation onto the surroundings by uniformly achieving the high frequency induction heating of the lump metal in the levitation condition, and melting the metal lump immediately before the lump metal is melted by the high frequency induction heating under the condition where the rotation of the lump metal is stopped. CONSTITUTION:The intensity of the eddy current flowing in the surface of a lump metal 9 is partially differentiated by generating the variation in the magnetic field generated in a cylindrical body 11 by using the metallic cylindrical body 11 where the sharing ratio of slits 16 in the circumferential direction is differentiated. Then, the condition where the lump metal 9 is heated in the in-air float heating manner while the lump metal being rotated and the condition where the lump metal is heated in the levitation heating manner while the lump metal being stopped are selectively switched by adjusting the relative rotative position of the cylindrical body 11 relative to a high frequency induction heating coil 12.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for floating and heating a metal lump in the air, and its apparatus, and more particularly, it is suitable for use as a melting method and a melting apparatus in precision casting of titanium or titanium alloy having extremely high temperature activity. It is a thing.

[0002]

2. Description of the Related Art When heating (melting) a metal mass, especially a metal mass such as titanium having high high temperature activity, to a high temperature, high frequency induction is performed in a floating state in the air so as not to contact with other members and cause a reaction. Most ideal is heating. Therefore, the present applicant previously proposed the airborne levitating heating device 1 shown in FIGS. 9 and 10.

When heating a metal ingot using this apparatus 1, the metal ingot 2 to be heated is formed of a metal cylindrical body 4 in which a plurality of slits 3 having equal widths are formed at equal intervals. Electromagnetic force directed upward to the metal ingot 2 by supplying a high-frequency current from the high-frequency power source 6 to the spiral high-frequency induction heating coil 5 arranged in the hollow portion and surrounding the outer periphery of the cylindrical body 4. Is applied to perform high-frequency induction heating under a floating condition in the air.
When performing precision casting, the metal ingot 2 is heated and melted and cast into a mold.

The mechanism of heating and melting the metal ingot 2 will be described below. That is, when a high frequency current (Jo) is passed through the high frequency induction heating coil 5, a magnetic flux (Φ) generated by the high frequency current (Jo) acts on the metal mass 2 through the slit 3 of the cylindrical body 4, and the metal mass 2 An induced current (Je) flows (see FIGS. 9 and 11). As a result, the metal ingot 2 is Joule heated. At this time, the metal block 2
An electromagnetic force (F) is generated in the metal ingot 2 by the interaction between the induced current (Je) flowing on the surface of the and the magnetic flux (Φ), and the direction of this electromagnetic force (F) is the cylindrical body 4 according to Fleming's left-hand rule.
The direction is upward (diagonally upward) with respect to the direction toward the axis center of. That is, the induced current (Je) is in the direction along the circumferential direction of the cylindrical body 4, and the direction of the magnetic flux (Φ) at the upper end side position of the cylindrical body 4 on which the metal mass 2 is placed is shown by an arrow H in FIG. Because it can be bent like this. Therefore, the upward component force (Fu) acts as a levitation force on the metal block 2,
As a result, the metal ingot 2 is held in a state of being levitated in the air in the vicinity of the upper end of the cylindrical body 4 and is subjected to high frequency induction heating. The magnitude of the electromagnetic force (F) depends on the induced current (J
The value is proportional to the product of e) and the magnetic flux density (B).

[0005]

In the aerial levitation heating device 1 having such a configuration, the magnetic flux generated from the high frequency induction heating coil 5 is not uniform in the winding direction (circumferential direction), and the magnetic flux of each part is not uniform. The densities are different. In particular,
Since the currents flowing through the lead portions 5a and 5b of the coil 5 are in opposite directions, the magnetic flux density near these lead portions 5a and 5b is relatively small, and the magnetic flux near the coil body portion 5c facing the lead portions 5a and 5b is relatively small. The density is relatively high.
Further, since the coil 5 is spirally wound, its uppermost winding portion is inclined with respect to the horizontal plane. Therefore, the induced current (eddy current) flowing in the surface portion of the metal ingot 2 adjacent to the uppermost side of the winding portion and the magnetic flux density acting on the surface portion are different from the surface opposite to the surface portion (the winding portion). Is larger than the surface portion of the metal ingot 2 corresponding to the lowermost portion), and the electromagnetic force generated on the surface portion is larger than the surface portion on the opposite side.

As described above, since the electromagnetic force acting from the high frequency induction heating coil 5 on each surface of the metal ingot 2 is different, this causes the metal ingot 2 to rotate at a high speed in a certain direction around the horizontal axis. While being (rotated), it is uniformly induction heated.

However, when the metal block 2 is rotated, when the metal block 2 is heated and melted, the molten metal may be scattered around by the centrifugal force accompanying the rotation. If such a situation occurs, not only will the loss of the material (the metal block 2) be caused, but also the melting operation will be accompanied by a great risk.

The present invention has been made to solve the above problems, and an object of the present invention is to impart uniform heat to a metal block by rotating it until just before the melt temperature reaches the melting temperature. An object of the present invention is to provide a method for floating and heating in the air, which can stop the rotation of a metal ingot immediately before reaching it, and an apparatus therefor.

[0009]

In order to achieve the above-mentioned object, in the airborne levitating heating method of the present invention, the outer circumference of a metallic cylindrical body having a plurality of slits radially extending in the radial direction is formed. Inside the hollow portion of the cylindrical body by coaxially surrounding it with a high-frequency induction heating coil, arranging the axes of the cylindrical body and the high-frequency induction heating coil along the vertical direction, and supplying a high-frequency current to the high-frequency induction heating coil. By applying an electromagnetic force directed upward to the metal mass in the method of performing high frequency induction heating while levitating the metal mass in the air, using a metal cylindrical body made different in the occupation ratio of the slit in the circumferential direction, By adjusting the relative rotational position of the cylindrical body with respect to the high-frequency induction heating coil, a state of floating and heating in the air while rotating the metal block is obtained. Rolling is stopped so that switch selectively to the state of airborne heat.

Further, in the aerial levitation heating apparatus of the present invention,
(A) A metal cylindrical body having a plurality of slits radially extending along a radial direction and having different occupancy ratios of the slit portions in the circumferential direction along the circumferential direction, ) A high frequency induction heating coil which is arranged so as to coaxially surround the outer periphery of the cylindrical body and whose axis is arranged along the vertical direction, and (c) a high frequency which supplies a high frequency current to the high frequency induction heating coil. And a rotation driving means for rotating and driving the cylindrical body with respect to the high frequency induction heating coil about an axis, and (d) a relative rotation position of the cylindrical body with respect to the high frequency induction heating coil. By adjusting, the metal ingot in the hollow portion of the cylindrical body is selectively rotated or stopped to be floated and heated in the air.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 shows an aerial levitation heating apparatus 10 for carrying out the aerial levitation heating method according to the present invention. This apparatus 10 includes a copper cylindrical body 11 for accommodating a metal mass 9 to be heated in an internal space (hollow portion), and a spiral high-frequency induction heating coil 12 arranged so as to surround the outer circumference of the cylindrical body 11. And a high frequency power supply 13 for supplying a high frequency current (electric power) to the coil 12.

The above-mentioned cylindrical body 11 is, as shown in FIG.
It has a plurality of slits 16 extending radially along the radial direction, and the slits 16 in the circumferential direction of the cylindrical body 11 are provided.
Occupancy ratios (arrangement ratios) of the parts are made different along the circumferential direction. That is, in this example, the plurality of slits 16 are formed at equiangular intervals, and the width L _{1 of the} slit 16a formed in one half 11a of the cylindrical body 11 and the other of the cylindrical body 11 are equal to each other. Half part 11b
The widths L _{2 of the} slits 16b formed in ₁ are different from each other (L ₁ > L ₂ ).

Then, each segment 1 between the slits 16
7 are connected to each other at the lower end of the cylindrical body 11. Further, the cooling water passage 1 is provided inside each segment 17.
8 is formed, and one end of the cooling water passage 18 is connected to the water guide pipe 19 and the other end is connected to the drainage pipe 20.

On the other hand, the high frequency induction heating coil 12 is formed by spirally winding a copper pipe. Cooling water is supplied to the hollow portion of the high frequency induction heating coil 12 and the lead portions 12a, 12b.
A high-frequency current is supplied from the high-frequency power source 13 via the. The coil 12 is a cylindrical body 11.
The coil 12 and the cylindrical body 11 are arranged so as to coaxially surround the outer periphery thereof, and the axes of the coil 12 and the cylindrical body 11 are aligned in the vertical direction.

Although not shown, the cylindrical body 11 is not shown.
Is rotated about its axis, whereby the slit 16a of the cylindrical body 11 with respect to the high frequency induction heating coil 12 is
A rotary drive mechanism for adjusting the relative position of 16b is provided.

A specific example of the apparatus 10 is as follows. (1) Material of ingot: Steel (S-45C) (2) Shape: Spherical, diameter 43mmφ Weight, 300g (5) Distance from top of coil to top of cylinder: 15m
m (6) High frequency heating condition (a) Preheating condition (non-floating state) (a) Frequency: 10 KHz (b) Output: 10 kW (c) Heating time: 8 seconds (b) Floating heating condition (a) Frequency: 10 KHz (B) Output: 28 kW

Next, the operation and action of the apparatus 10 for floating and heating the metal ingot 9 in the air will be described.

First, the metal mass 9 to be heated is placed on a mounting table (not shown), and the metal mass 9 is placed from below the cylindrical body 11 to the cylindrical body 1.
It is transferred into the hollow portion of No. 1 and placed at the levitation heating start position corresponding to the uppermost end of the high frequency induction heating coil 12. Then, a high-frequency current is supplied from the high-frequency power source 13 to the coil 12, and the metal ingot 9 is levitated by the vertical component force of the electromagnetic force generated with the high-frequency current. On the other hand, at the same time, by operating a transfer mechanism (not shown), the mounting table for the metal mass 9 is moved below the cylindrical body 11 and moved to a position deviating from the position directly below the cylindrical body 11.

Then, by adjusting the high-frequency current supplied to the high-frequency induction heating coil 12, the horizontal axis of the metal ingot 9 is arranged above the upper end surface 11c of the cylindrical body 11 and a part of the metal ingot 9 is formed in the cylindrical body. The metal ingot 9 is levitated in the air at a position arranged in the hollow portion 11 and high-frequency induction heating is performed at this position.

At this time, as shown in FIG. 1, the half portion 11b of the cylindrical body 11 provided with the narrow slit 16b is made to face the lead portions 12a and 12b of the high frequency induction heating coil 12, and the wide slit 16a is provided. The cylindrical body 1 is provided such that the half portion 11a of the cylindrical body 11 provided with the coil body 11 faces the coil body portion 12c corresponding to the lead portions 12a and 12b.
Place 1 By doing so, a relatively large electromagnetic force acts obliquely upward on the surface of the metal lump 9 facing the coil body portion 12c than the surface of the metal lump 9 facing the lead portions 12a and 12b. Is rotated at a high speed in the direction of arrow A in FIG.

When the arrangement of the cylindrical body 11 with respect to the high frequency induction heating coil 12 is completely opposite to the state shown in FIGS. 1 and 2, that is, the state is changed by 180 ° as shown in FIGS. 3 and 4. Slits 16a and 16
Depending on the selection condition of the width b, the direction of rotation of the metal ingot 9 is the direction of arrow B, which is the opposite of the direction of arrow A, as shown in FIG.

Under this condition, the metal ingot 9 is uniformly heated in a rotating state and immediately before the metal ingot 9 reaches the melting temperature, a rotation drive mechanism (not shown) is activated to move the cylindrical body 11 around its axis, for example. Approximately 90 ° (This rotation angle is determined by the slit 16a,
16b width and arrangement interval, inclination angle of the high frequency induction heating coil 12 with respect to the cylindrical body 11, and lead portions 12a, 1
It depends on conditions such as the arrangement of 2b. ) Only rotate.
As a result, as shown in FIG. 5, the wide slit 16a of the cylindrical body 11 is arranged corresponding to the portion 12d between the lead portion 12a and the coil body portion 12c, and the narrow slit 16b of the cylindrical body is formed in the portion 12d. It is arranged corresponding to the facing portion 12e. With such an arrangement relationship, the magnitude of the electromagnetic force acting on the surface of the metal ingot 9 becomes equal and the forces acting in the rotation direction are offset, so that the rotation of the metal ingot 9 is stopped.

Under this condition, high-frequency induction heating is continued to heat the metal ingot 9 to a melting temperature or higher to bring it into a molten state. Along with this, the molten metal 9'becomes completely spherical due to its surface tension (see FIG. 6).

Then, the supply of the high frequency current to the high frequency induction heating coil 12 is cut off. Along with this, the electromagnetic force (levitation force) acting on the molten metal 9'disappears, so that the molten metal 9'falls naturally and is cast into a mold (not shown). Then, the molten metal 9'cast in the mold is naturally cooled, and a precision cast product having a predetermined shape is obtained.

According to the apparatus 10 as described above, the metal ingot 9 is heated in the solid state while being rotated in the solid state until the melting temperature is reached, so that the whole metal ingot 9 can be heated uniformly. Immediately before melting, the rotation of the metal ingot 9 is stopped by adjusting the relative rotational position of the cylindrical body 11 with respect to the high-frequency induction heating coil 12, so that the molten metal 9 ′ may be scattered around. Occurrence can be prevented. Further, the rotation speed of the metal ingot 9 during heating can be arbitrarily adjusted by adjusting the rotation position of the cylindrical body 11.

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, a plurality of slits 16 in the cylindrical body 11
The arrangement configuration of can be variously changed. That is, as shown in FIG. 7, the widths of the slits 16 are all the same, and the arrangement intervals of the slits 16 in the circumferential direction of the cylindrical body 11 are made different, and the arrangement ratio of the slits (the entire circumference of the cylindrical body 11 is On the other hand, the ratio occupied by the slit 16) may be changed along the circumferential direction. Further, as shown in FIG. 8, the slits 16 whose width gradually changes may be arranged at equal angular intervals.

[0029]

As described above, according to the method and apparatus of the present invention, by rotating the metal cylindrical bodies having different occupying ratios of the slits in the circumferential direction and arranging them at the predetermined positions,
High-frequency induction heating is performed by selectively switching the metal mass floating in the air to the rotation or rotation stop state, so that uniform heating under the rotation state can be performed and immediately before melting. It is possible to prevent the molten metal from scattering by stopping the rotation. Therefore, according to the present invention, the metal ingot can be heated (melted) with a simple device at a uniform temperature without contacting with other members while ensuring the safety of work, and a high-quality cast product. Etc. can be obtained.

[Brief description of drawings]

FIG. 1 is a plan view of an aerial levitation heating apparatus according to the present invention.

2 is a cross-sectional view of the device shown in FIG.

FIG. 3 is a plan view of the airborne heating apparatus showing a state in which the cylindrical body is arranged at a position rotated by 180 ° from the position shown in FIG.

4 is a cross-sectional view of the device shown in FIG.

5 is a plan view of the aerial levitation heating apparatus showing a state in which the cylindrical body is arranged at a position rotated by approximately 90 ° from the position shown in FIG. 1. FIG.

6 is a cross-sectional view of the device shown in FIG.

FIG. 7 is a plan view showing a modified example of a slit provided in a cylindrical body.

FIG. 8 is a plan view showing another modified example of the slit provided in the cylindrical body.

FIG. 9 is a cross-sectional view of an aerial levitation heating device including cylindrical bodies in which slits having the same width are provided at equal intervals.

FIG. 10 is a plan view of the device shown in FIG.

FIG. 11 is a sectional view showing a part of the above-mentioned cylindrical body by cutting out.

[Explanation of symbols]

9 metal block 10 slits L ₁ levitation heating device 11 the cylindrical body 12 of the wide high-frequency induction heating coil 16 slits 16a slit 16b narrow, L ₂ slit width

Claims (5)

[Claims] 1. A high-frequency induction heating coil coaxially surrounds the outer circumference of a metal cylindrical body in which a plurality of slits radially extending in the radial direction are formed, and the axes of the cylinder and the high-frequency induction heating coil. Is arranged along the vertical direction, and by applying a high-frequency current to the high-frequency induction heating coil, an electromagnetic force is applied upward to the metal mass in the hollow portion of the cylindrical body, and the high-frequency wave is generated while levitating the metal mass in the air. In the method of performing the induction heating, using a metal cylinder made of different occupancy ratio of the slit in the circumferential direction, by adjusting the relative rotational position of the cylinder with respect to the high-frequency induction heating coil, the metal It is characterized in that it can be selectively switched between the state of floating and heating in the air while rotating the mass and the state of floating and heating in the air by stopping the rotation. A method for floating and heating a metal block in the air. 2. Up to just before the melting temperature of the metal ingot, the metal ingot is levitationally heated in a rotating state, and the metal ingot is stopped in rotation just before reaching the melting temperature, and thereafter stopped in rotation. The method for airborne levitating and heating of a metal ingot according to claim 1, wherein melting is performed by air levitating and heating under a state. 3. (a) A metal cylinder having a plurality of slits radially extending along a radial direction and having different occupancy ratios of the slit portions in the circumferential direction along the circumferential direction. A body, and (b) a high-frequency induction heating coil arranged so as to coaxially surround the outer circumference of the cylindrical body and having an axis extending in the vertical direction, and (c) a high-frequency induction heating coil. A high-frequency power source for supplying an electric current; and (d) a rotation driving unit that rotationally drives the cylindrical body around the axis with respect to the high-frequency induction heating coil, respectively. By adjusting the relative rotational position, the metal ingot in the hollow portion of the cylindrical body is selectively put into a rotating state or a rotation-stopped state to be floated and heated in the air. Levitation heating device. 4. The metal ingot according to claim 3, wherein the widths of the plurality of slits are all the same, and the arrangement intervals of the plurality of slits in the circumferential direction are partially different. Levitation heating method. 5. The aerial of metal ingot according to claim 3, wherein the plurality of slits are arranged at equal intervals in the circumferential direction, and the widths of the plurality of slits are partially different. Levitation heating method.