JP2012040590A - Centrifugal casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To allow heating of a die to be inhibited and lowering of cooling speed to be reduced, even when molten metal is formed by performing induction heating above the die, in a centrifugal casting apparatus.SOLUTION: The centrifugal casting apparatus 1 includes: an induction heating coil 7 for obtaining the molten metal 10 by induction heating of a metallic material; the die 4 which has a cavity 4c in which casting is performed by injecting the molten metal 10 and a molten metal inlet 4a for injecting the molten metal 10 to the cavity 4c, and in which the molten metal inlet 4a is arranged below the induction heating coil 7; and electromagnetic shielding 5 which is provided between the induction heating coil 7 and the die 4. The electromagnetic shielding 5 is provided at least in an area outside in a radial direction from an internal circumference of the minimum coil of the die 4 side of the induction heating coil 7 in view of a direction along the center axis Oof the induction heating coil 7.

Description

  The present invention relates to a centrifugal casting apparatus.

Conventionally, a centrifugal casting apparatus that performs casting by pouring a molten metal into a rotating mold is known. For example, Patent Document 1 describes a rotary mold used in such a centrifugal casting apparatus.
As a technique for obtaining a molten metal, electromagnetic induction heating is known in which a metal material is heated by generating a magnetic field by passing a high-frequency current through an induction heating coil. As a method of injecting molten metal by electromagnetic induction heating into the centrifugal casting machine, electromagnetic induction heating is performed above the mold, and when the molten metal is formed, induction heating is stopped, so that the molten metal is poured into the mold. There is known a system in which a metal melt is poured into a mold by dropping it at an inlet.

JP 2008-126313 A

However, the centrifugal casting apparatus using the conventional induction heating as described above has the following problems.
The mold used for the centrifugal casting apparatus needs to be made of a material that can quench the molten metal so that the molten metal is solidified during rotation. For this reason, a metal mold | die is comprised with a metal material like the technique of patent document 1, for example.
Moreover, in the centrifugal casting apparatus using induction heating, if the molten metal is cooled too much during the fall of the molten metal, the fluidity in the mold deteriorates, so it is necessary to place the induction heating coil near the mold. There is.
For this reason, in the conventional centrifugal casting apparatus using induction heating, a part of the magnetic flux generated by the induction heating coil leaks to the mold, so that the mold is heated during induction heating. As a result, there is a problem that the cooling rate of the molten metal injected into the mold is reduced and solidification takes time.
In addition, for example, when casting an amorphous alloy as described in Patent Document 1, it is necessary to rapidly cool at a cooling rate equal to or higher than a constant rate. Therefore, when the mold is heated by induction heating, There is also a problem that the mold configuration is complicated because the mold must be forcibly cooled by flowing cooling water into the mold.

  The present invention has been made in view of the above problems, and even when induction heating is performed above a mold to form a molten metal, the heating of the mold can be suppressed, and the cooling rate is lowered. An object of the present invention is to provide a centrifugal casting apparatus capable of reducing the above.

  In order to solve the above problems, a centrifugal casting apparatus of the present invention includes an induction heating coil for obtaining a molten metal by electromagnetic induction heating of a metal material, a cavity for injecting the molten metal to perform casting, and the cavity A molten metal injection port for injecting the molten metal, the molten metal injection port disposed below the induction heating coil, and an electromagnetic wave provided between the induction heating coil and the mold A shield, and the electromagnetic shield is provided at least in a region radially outside the smallest coil inner circumference on the mold side of the induction heating coil as viewed from the direction along the central axis of the induction heating coil. The configuration is as follows.

  In the centrifugal casting apparatus of the present invention, the induction heating coil is an induction floating heating coil that induces and floats the molten metal, and the electromagnetic shield is the coil as viewed from a direction along a central axis of the induction heating coil. It is preferable to have a through-hole through which the molten metal passes while being provided in a region radially inward from the inner periphery.

  In the centrifugal casting apparatus of the present invention, it is preferable to include a shield moving mechanism that moves at least a part of the electromagnetic shield in the radial direction of the induction floating coil with respect to the mold.

  In the centrifugal casting apparatus of the present invention, it is preferable that a low permeability layer having a lower relative permeability than the electromagnetic shield is provided between the electromagnetic shield and the mold.

  In the centrifugal casting apparatus having the low magnetic permeability layer of the present invention, it is preferable that the electromagnetic shield is fixed on the mold through the low magnetic permeability layer.

  In the centrifugal casting apparatus having the low magnetic permeability layer of the present invention, it is preferable that the low magnetic permeability layer has a heat insulating layer that suppresses heat transfer from the electromagnetic shield.

  In the centrifugal casting apparatus of the present invention, it is preferable that the electromagnetic shield is disposed on the induction heating coil side with respect to the middle between the induction heating coil and the mold.

  Moreover, in the centrifugal casting apparatus in which the electromagnetic shield of the present invention is disposed on the induction heating coil side with respect to the middle between the induction heating coil and the mold, the electromagnetic shield is disposed on the mold side of the electromagnetic shield. It is preferable that a low permeability layer having a lower relative permeability than that of the shield is provided.

  According to the centrifugal casting apparatus of the present invention, since the magnetic flux leaking from the induction heating coil to the mold side can be shielded by the electromagnetic shield, the mold is used even when the metal melt is formed by induction heating above the mold. The temperature rise can be suppressed, and the effect of reducing the cooling rate can be achieved.

It is a typical fragmentary sectional view showing the composition of the centrifugal casting device concerning a 1st embodiment of the present invention. It is typical sectional drawing which shows the structure of the centrifugal casting apparatus which concerns on the 1st Embodiment of this invention. It is AA sectional drawing in FIG. It is a typical magnetic force line figure for demonstrating the effect | action of an electromagnetic shield. It is typical sectional drawing which shows the structure of the centrifugal casting apparatus which concerns on the 2nd Embodiment of this invention. FIG. 6 is a B view in FIG. 5. It is typical sectional drawing which shows the structure of the centrifugal casting apparatus which concerns on the 3rd Embodiment of this invention. It is CC sectional drawing in FIG. It is typical sectional drawing which shows the principal part of the centrifugal casting apparatus which concerns on the 1st modification of the 3rd Embodiment of this invention. It is typical sectional drawing which shows the principal part of the centrifugal casting apparatus which concerns on the 2nd modification of the 3rd Embodiment of this invention. It is typical sectional drawing which shows the structure of the centrifugal casting apparatus which concerns on the 4th Embodiment of this invention. FIG. 12 is a view as viewed in FIG. 11 and a view as viewed in FIG. 11 when the mold is rotating.

  Embodiments of the present invention will be described below with reference to the accompanying drawings. In all the drawings, even if the embodiments are different, the same or corresponding members are denoted by the same reference numerals, and common description is omitted.

[First Embodiment]
A centrifugal casting apparatus according to a first embodiment of the present invention will be described.
FIG. 1 is a schematic partial sectional view showing the configuration of a centrifugal casting apparatus according to the first embodiment of the present invention. FIG. 2 is a schematic cross-sectional view showing the configuration of the centrifugal casting apparatus according to the first embodiment of the present invention. 3 is a cross-sectional view taken along line AA in FIG.
In addition, since each drawing is a schematic diagram, the shape and dimension are exaggerated (the following drawings are also the same).

The schematic configuration of the centrifugal casting apparatus 1 of the present embodiment includes an induction heating coil 7, a mold 4, an electromagnetic shield 5, and a radiation thermometer 9, as shown in FIGS. Or it is accommodated in the chamber 2 which can be adjusted to the low pressure atmosphere in which the inert gas was inject | poured.
The induction heating coil 7 is for obtaining a molten metal 10 (see FIG. 2) by electromagnetic induction heating of a metal material for centrifugal casting, and a refrigerant flow path 7c for passing a refrigerant such as water is provided therein. A coil winding portion is formed by winding the metal tube. Further, at the upper end and the lower end of the coil winding portion, an upper wiring portion 7a and a lower wiring portion 7b made of the same metal tube are extended to the side of the coil winding portion.
The center axis O ₁ of the coil winding part of the induction heating coil 7 _(hereinafter referred to simply as the central axis O ₁ of the induction heating coil 7), in the present embodiment are arranged along the vertical axis.
The upper wiring portion 7 a and the lower wiring portion 7 b are connected to the induction heating coil support portion 8, which is a support member erected in the vertical direction from the bottom surface of the chamber 2 on the side of the induction heating coil 7.
That is, although illustration is omitted, inside the induction heating coil support portion 8, a connector portion that is provided outside the chamber 2 and is electrically connected to a power source portion that supplies a high-frequency current, A pipe line connecting part for connecting the refrigerant flow path 7c is provided in a refrigerant circulation part that is provided outside and circulates the refrigerant in the refrigerant flow path 7c. The upper wiring part 7a and the lower wiring part 7b are connected to the connector part. And is mechanically connected to the pipe connecting portion.
Although the material of the metal tube which comprises the induction heating coil 7 is not specifically limited, In this embodiment, the copper tube is used as an example.

In the present embodiment, the induction heating coil 7 uses an induction floating heating coil that can obtain a molten metal 10 by electromagnetic induction heating of a metal material and can induce and float the molten metal 10 inside the induction heating coil 7.
The structure of the coil winding part of the induction heating coil 7 is connected to the end part of the upper wiring part 7a, and the upper coil part 7A wound in a spiral shape whose diameter increases from the upper side to the lower side, and the upper coil part 7A. The lower coil portion 7B wound in a spiral shape opposite to the upper coil portion 7A, the lower end portion of the upper coil portion 7A, and the lower coil It comprises a winding direction reversing part 7C that connects the upper end part of the part 7B. A lower wiring portion 7b is connected to the lower end portion of the lower coil portion 7B.
With such a configuration, the winding diameter of the coil winding portion of the induction heating coil 7 has a maximum outer diameter _Dmax at the lower end of the upper coil portion 7A or the upper end of the lower coil portion 7B, as shown in FIG. The diameter of the inner circumference of the coil at the upper end of the upper coil portion 7A is D _A (where D _A <D _max ), and the diameter of the inner circumference of the coil at the lower end of the lower coil portion 7B is D _B (where D _B <D _max ). In the present embodiment, D _A > D _B.

As shown in FIG. 2, the mold 4 has a disk-like shape having a cavity 4 c for injecting the molten metal 10 for casting and a molten metal inlet 4 a for injecting the molten metal 10 into the mold 4. It is a member, and below the induction heating coil 7, the mold upper surface 4d is arranged along the horizontal plane.
Melt inlet 4a, in this embodiment, it consists of a vertical hole portion in the center of the plan view of the mold top surface 4d of the die 4 has a circular opening with a diameter D _0. The diameter D of the molten metal inlet 4a ₀ is a diameter smaller than the diameter D _B of the inner circumference coil of the lower end of the lower coil portion 7B.
The cavity 4c is provided in an appropriate shape according to the shape of the molded product, and is disposed on the side of the molten metal injection port 4a. The cavity 4c is communicated with the inside of the molten metal inlet 4a by a tubular molten metal channel 4b extending in the radial direction of the mold 4 from the center of the molten metal inlet 4a.
Note that FIG. 2 is a schematic diagram, and the mold 4 is drawn as a single member. However, since the molded product solidified in the cavity 4c is removed, it can be divided into a plurality of mold members. It is like that.

  As a material of the mold 4, an appropriate metal that can be used for centrifugal casting can be employed. In this embodiment, copper (relative magnetic permeability: 0.999991) is used as an example.

In addition, the mold 4 is connected to the rotation drive unit 3 that is rotated around the rotation center axis O ₂ along the vertical axis by a motor (not shown) provided outside the chamber 2 at the center position on the lower surface side. . The rotation center axis O ₂ of the rotation drive unit 3 is aligned with the center axis O ₁ of the induction heating coil 7.
For this reason, when the mold 4 is rotated around the rotation center axis O ₂ by the rotation drive unit 3, the molten metal injection port 4 a is rotated in a state coaxial with the center axis O ₁ of the induction heating coil 7.
The rotation speed of the rotation drive unit 3 can be varied in the range of 0 rpm to 10000 rpm.

The electromagnetic shield 5 is a member for electromagnetically shielding the mold 4 by trapping magnetic lines (magnetic flux) in the electromagnetic field generated during induction heating by the induction heating coil 7. In this embodiment, as shown in FIG. 3, it consists of a perforated disk provided with a circular through-hole 5a in the center.
The outer diameter of the electromagnetic shielding 5 D ₂ is the maximum outer diameter D _max or more induction heating coils 7. The inner diameter D ₁ of the through-hole 5a is smaller in diameter than the large diameter and the diameter D _B of the inner circumference coil of the lower end of the lower coil portions 7B, than the inner diameter D ₀ of the molten metal inlet 4a.

Moreover, in this embodiment, the electromagnetic shield 5 is comprised with the electromagnetic steel plate whose relative permeability is 3.9 as an example. However, the material of the electromagnetic shield 5 can employ | adopt the appropriate material whose relative magnetic permeability is higher than the metal mold | die 4, and is not limited to an electromagnetic steel plate.
Examples of suitable materials for the electromagnetic shield 5 include SUS304 (relative magnetic permeability: 1.007 to 1.8), SKD61 (relative magnetic permeability: 2000 to 7000), permalloy (ratio) depending on the material of the mold 4. Magnetic permeability: 14000-45000), nickel (relative magnetic permeability: 600), MnZn ferrite (relative magnetic permeability: 2000), pure iron (relative magnetic permeability: 200000), cobalt (relative magnetic permeability: 270) and the like. it can.
Note that “electromagnetic shield” is distinguished from “electromagnetic shield” composed of a conductive net or plate to trap energy waves such as radio waves, light, and X-rays, and is also referred to as “magnetic field shield”. be called.

The electromagnetic shield 5 is supported in the horizontal direction by a bar-shaped electromagnetic shield support member 6 extending laterally from the induction heating coil support portion 8, and the through hole 5 a is interposed between the induction heating coil 7 and the mold 4. Is disposed at a position passing through the rotation center axis O ₂ of the rotation drive unit 3.
The material of the electromagnetic shield support member 6 is preferably a material having a lower relative permeability than that of the electromagnetic shield 5 so that the magnetic field distribution by the induction heating coil 7 is not greatly affected.

The radiation thermometer 9 measures the temperature of the molten metal 10 that is inductively suspended inside the induction heating coil 7 based on the intensity of the radiated light from the molten metal 10. In the present embodiment, radiation light that is fixed to the inner wall portion of the chamber 2 at the side of the floating position of the molten metal 10 and passes through the gap between the windings of the induction heating coil 7 can be received.
Thus, in this embodiment, since the electromagnetic shield 5 does not cover the side of the induction heating coil 7 at the floating position of the molten metal 10, the temperature of the molten metal 10 from the side of the induction heating coil 7 is measured by the radiation thermometer 9. Measurements can be made.

Next, the operation of the centrifugal casting apparatus 1 will be described focusing on the action of the electromagnetic shield 5.
FIG. 4 is a schematic magnetic field diagram for explaining the operation of the electromagnetic shield.

In order to perform casting with the centrifugal casting apparatus 1, a metal material necessary for forming is placed inside the induction heating coil 7, and the induction heating coil 7 is made to flow through the refrigerant flow path 7 c of the induction heating coil 7. A high frequency current is passed through the induction heating coil 7 while cooling. At this time, the amount of metal material, the outer diameter is set to be smaller amount than the inner diameter D ₀ of the molten metal inlet 4a when it is melted.
Thereby, a magnetic field is generated around the induction heating coil 7, the metal material is induction heated, and the molten metal 10 is formed.
In the induction heating coil 7, the upper coil portion 7A and the lower coil portion 7B have opposite coil winding directions, and thus the upper coil portion 7A and the lower coil portion 7B generate magnetic fields in opposite directions. Thus, the melt 10 receives repulsive force from these magnetic fields are induced suspended in the position of the boundary between the upper coil portion 7A and a lower coil portion 7B on the center axis O ₁ of the induction heating coil 7.

On the other hand, the operator starts the rotation of the rotation driving unit 3 so that the number of rotations reaches a predetermined value before the molten metal 10 reaches a predetermined molding start temperature.
Next, the operator cuts off the high frequency current to the induction heating coil 7 when the temperature of the molten metal 10 measured by the radiation thermometer 9 reaches the molding start temperature.
Thereby, the magnetic field by the induction heating coil 7 disappears, and the molten metal 10 that has lost its buoyancy falls freely.
The molten metal 10 passes through the inner circumference of the through hole 5a of the electromagnetic shield 5 through the inner circumference of the coil on the lower end side of the lower coil portion 7B, and falls into the molten metal inlet 4a.
The molten metal 10 that has fallen into the molten metal inlet 4a is urged radially outward by centrifugal force, and is filled into the cavity 4c through the molten metal flow path 4b. During this time, the molten metal 10 is cooled in contact with the mold 4 and solidifies in the cavity 4c along the shape of the cavity 4c.
When all the molten metal 10 in the cavity 4c has been cooled below the solidification temperature, the rotational drive unit 3 is stopped, the mold 4 is disassembled, and the molded product is demolded.
The centrifugal casting with the centrifugal casting device 1 is thus completed.

Next, with reference to FIG. 4, the difference by the presence or absence of the electromagnetic shield 5 is demonstrated about the magnetic force line around the induction heating coil 7 at the time of induction heating.
FIG. 4 schematically shows the distribution of the lines of magnetic force generated in the vertical cross section including the central axis O ₁ when the half (right half in the figure) of the electromagnetic shield 5 of this embodiment is omitted.
The magnetic field distribution generated around the upper coil portion 7A is substantially bilaterally symmetric, but the magnetic field distribution generated around the lower coil portion 7B differs depending on the presence or absence of the electromagnetic shield 5.
When the electromagnetic shield 5 is disposed, as shown in the left half of the figure, the magnetic lines M ₁ and M ₂ extending vertically downward from the inner peripheral portion of the lower coil portion 7B are compared with the inner surface of the through-hole 5a. It penetrates into the inside of the electromagnetic shield 5 having a large magnetic permeability, exits from the outer peripheral side surface of the electromagnetic shield 5, and moves toward the upper end side of the lower coil portion 7B.
Thereby, the magnetic force line distribution which circulates the inner peripheral side and outer peripheral side of the lower coil part 7B is formed.
Since the electromagnetic shield 5 has a higher relative permeability than the mold 4, the magnetic field lines passing through the vicinity of the electromagnetic shield 5 almost enter the electromagnetic shield 5 and hardly reach the mold 4 below the electromagnetic shield 5. . That is, the mold 4 is electromagnetically shielded by the electromagnetic shield 5 against the magnetic field formed by the lower coil portion 7B.

As a result, the mold 4 is hardly subjected to induction heating by the magnetic field of the lower coil portion 7B, and the temperature before induction heating is substantially maintained while the induction heating of the molten metal 10 continues.
Therefore, after the induction heating is finished, the molten metal 10 that has dropped into the molten metal inlet 4a is rapidly cooled at a cooling rate (temperature decrease per unit time) according to the temperature difference between the temperature of the molten metal 10 and the temperature of the mold 4. Will be. For this reason, the molten metal 10 solidifies quickly.

In this embodiment, the outer diameter of the electromagnetic shield 5, an induction maximum outer diameter D _max of the heating coils 7 _(shown in Figure 3 circularly C ₂₎ above, the lower end portion of the inner diameter of the through hole 5a is lower coil portion 7B Is smaller than the diameter D _B (indicated by a circle C ₁ in FIG. 3) of the inner circumference of the coil. For this reason, when viewed from the direction along the central axis O ₁ , the electromagnetic shield 5 is located in a range where it overlaps the coil winding portion of the induction heating coil 7, and a high electromagnetic shielding effect is obtained.
Further, when the electromagnetic shield 5 is arranged on the induction heating coil 7 side from the middle between the induction heating coil 7 and the mold 4, a good electromagnetic shielding effect can be obtained even if the electromagnetic shield 5 is a small size. Can do.

On the other hand, when the electromagnetic shield 5 is not arranged, as shown in the right half of the figure, the magnetic lines of force M ₃ and M ₄ extending vertically downward from the inner peripheral portion of the lower coil portion 7B are the mold 4 And a part of the magnetic flux of the induction heating coil 7 leaks into the mold 4. For this reason, an eddy current is generated inside the mold 4 due to the intruding lines of magnetic force, and the mold 4 is heated by the Joule heat. That is, the mold 4 is subjected to induction heating.

As a result, while the induction heating of the molten metal 10 continues, the mold 4 is also gradually induction heated. Thereby, the temperature of the mold 4 rises.
For this reason, when the molten metal 10 falls to the molten metal inlet 4a, the temperature of the mold 4 is higher than that of the centrifugal casting apparatus 1 of the present embodiment. The difference is smaller than that of the present embodiment, and the cooling rate is reduced.
When the cooling rate decreases, the time required for solidification of the molten metal 10 becomes longer, and the molding time becomes longer. In addition, for example, when a cooling rate of a certain speed or more is required as in the case of casting an amorphous alloy, there is a possibility that the amorphousness varies.

  Thus, according to the centrifugal casting apparatus 1, since the magnetic flux leaking from the induction heating coil 7 to the mold 4 side can be shielded by the electromagnetic shield 5, induction heating is performed above the mold 4 so that the molten metal 10 is formed. Even in the case of forming, the temperature rise of the mold 4 can be suppressed, and the decrease in the cooling rate can be reduced.

[Second Embodiment]
Next, a centrifugal casting apparatus according to the second embodiment of the present invention will be described.
FIG. 5 is a schematic cross-sectional view showing a configuration of a centrifugal casting apparatus according to the second embodiment of the present invention. FIG. 6 is a view as seen from B in FIG.

  As shown in FIGS. 5 and 6, the centrifugal casting apparatus 1 </ b> A of this embodiment is replaced with an electromagnetic shield 12, a low-permeability instead of the electromagnetic shield 5 and the electromagnetic shield support member 6 of the centrifugal casting apparatus 1 of the first embodiment. A magnetic layer 11 is provided. Hereinafter, a description will be given centering on differences from the first embodiment.

Electromagnetic shield 12 is made of the same material as the electromagnetic shield 5 has the same outer diameter of the die 4, holes through hole 12a is provided with similar internal diameter D ₁ and the through-hole 5a in the center autumn It is a member formed in a disk shape, and is fixed on the upper surface 4 d of the mold 4 with the low magnetic permeability layer 11 interposed therebetween.
Examples of the method for fixing the electromagnetic shield 12 to the mold 4 include fastening with screws at the outer periphery, adhesion, and brazing.
In particular, when a screw is used to fasten the mold 4, an alumina ceramic screw having a low relative permeability is suitable in order to prevent magnetism from leaking from the electromagnetic shield 5 to the mold 4 via the screw. .
The low magnetic permeability layer 11 is for magnetically separating the electromagnetic shield 12 and the mold 4 fixed on the mold 4 by preventing magnetic field lines from leaking from the electromagnetic shield 12 to the mold 4 side. It is made of a material having a relative permeability lower than that of the electromagnetic shield 12 at least. The larger the difference between the relative permeability of the electromagnetic shield 12 and the relative permeability of the low permeability layer 11, the better.
The shape of the low permeability layer 11 has the same outer diameter of the mold 4, the central portion to the molten metal inlet 4a and the through hole 11a is perforated disk-shaped provided with an inner diameter D ₀ similar It is said. For this reason, in this embodiment, the low magnetic permeability layer 11 is provided so as to cover the entire upper surface 4 d of the mold 4.
As a material of the low magnetic permeability layer 11, a material having a relative magnetic permeability of 1.05 or less is suitable. Examples of such materials include alumina (Al ₂ O ₃ ), aluminum nitride (AlN), silicon carbide (SiC), boron nitride (BN), silicon nitride (Si ₃ N ₄ ), aluminum (Al), copper (Cu) etc. can be mentioned. Moreover, the low magnetic permeability layer 11 may be comprised from the air layer.

In addition, when the material of the electromagnetic shield 12 is a material having a large eddy current loss, the low magnetic permeability layer 11 is preferably made of a material having a lower thermal conductivity than the electromagnetic shield 12.
For example, when an electromagnetic steel plate is employed as the electromagnetic shield 12, the electromagnetic steel plate generates heat due to an eddy current generated in the electromagnetic steel plate. For this reason, as the low magnetic permeability layer 11, for example, a material having a low thermal conductivity such as alumina is used to give the low magnetic permeability layer 11 a function as a heat insulating layer. It is preferable to suppress heat transfer to the mold 4.
Note that when the electromagnetic shield 12 is made of a material that is difficult to be heated due to low eddy current loss, such as ferrite, for example, since the heat generation due to the eddy current hardly occurs, the low permeability layer 11 has a specific permeability. The material may be selected only by the magnitude of the magnetic susceptibility. For example, a material having a high thermal conductivity such as aluminum may be adopted.

According to the centrifugal casting apparatus 1A, centrifugal casting can be performed in the same manner as the centrifugal casting apparatus 1 of the first embodiment.
The magnetic field generated by the induction heating coil 7 when performing induction heating enters the electromagnetic shield 12 that rotates together with the mold 4 and is trapped. Further, since the electromagnetic shield 12 and the mold 4 are magnetically separated by interposing the low permeability layer 11 between them, the magnetic lines of force emitted from the electromagnetic shield 12 are transmitted through the low permeability layer 11. The mold 4 does not enter.
For this reason, the temperature rise of the metal mold | die 4 can be suppressed similarly to the said 1st Embodiment, and the fall of a cooling rate can be reduced.

Moreover, in this embodiment, since the electromagnetic shield 12 is being fixed on the metal mold | die upper surface 4d of the metal mold | die 4 through the low magnetic permeability layer 11, the rigidity of electromagnetic shield 12 itself may be low. For this reason, even if it is the magnitude | size which substantially the whole mold upper surface 4d covers, plate | board thickness can be made thin, the arrangement space of a thickness direction can be reduced, and material cost can be reduced.
Thus, in this embodiment, since the thin electromagnetic shield 12 can cover substantially the entire upper surface 4d of the mold, the distance between the induction heating coil 7 and the mold 4 is compared with that of the first embodiment. In addition, the mold 4 can be electromagnetically shielded satisfactorily.

Moreover, in this embodiment, since the distance of the induction heating coil 7 and the metal mold | die 4 can be approached compared with the said 1st Embodiment, the fall distance of the molten metal 10 is reduced compared with the said 1st Embodiment. can do.
For this reason, the temperature drop during the fall of the molten metal 10 can be reduced, and the temperature of the molten metal 10 in the induction heating coil 7 can be lowered. As a result, the molten metal 10 can be obtained in a shorter time.
In addition, since the height of the chamber 2 can be further reduced as compared with the first embodiment, the chamber 2 can be downsized and the time required for adjusting the atmosphere in the chamber 2 can be shortened.
Thus, in this embodiment, since the formation time of the molten metal 10 can be shortened or the atmosphere adjustment time of the chamber 2 can be shortened, the molding efficiency can be improved.

Further, since the electromagnetic shield 12 is fixed on the mold 4, the positional relationship between the through-hole 12 a and the molten metal injection port 4 a is fixed, and by positioning when the mold 4 is connected to the rotation drive unit 3. , also the positioning of the center axis O ₁ of the induction heating coil 7 and the through hole 12a are performed simultaneously.

Moreover, since the fall distance of the molten metal 10 can be shortened, the molten metal 10 can be reliably dropped in the molten metal inlet 4a. Moreover, the splash of the molten metal 10 can be reduced.
Moreover, since the through-hole 12a can be formed in the vicinity of the molten metal injection port 4a, the size of the through-hole 12a can also be made the same size as the molten metal injection port 4a (D ₁ = D ₀ ). For this reason, the efficiency of an electromagnetic shield can be improved.

  In addition, when a material having low thermal conductivity is adopted as the low magnetic permeability layer 11, the low magnetic permeability layer 11 functions as a heat insulating layer, and therefore the temperature rise of the mold 4 due to heat conduction from the electromagnetic shield 12 is also increased. Can be reduced.

[Third Embodiment]
Next, a centrifugal casting apparatus according to the third embodiment of the present invention will be described.
FIG. 7 is a schematic cross-sectional view showing a configuration of a centrifugal casting apparatus according to the third embodiment of the present invention. 8 is a cross-sectional view taken along the line CC in FIG.

  As shown in FIGS. 7 and 8, the centrifugal casting apparatus 1 </ b> B of the present embodiment includes an electromagnetic shield 13 instead of the electromagnetic shield 5 of the centrifugal casting apparatus 1 of the first embodiment. Hereinafter, a description will be given centering on differences from the first embodiment.

Electromagnetic shield 13 is made of the same material as the electromagnetic shield 5, the inner diameter _{D 3 (however, D B <D 3 <D} max) from the upper opening 13a having a lower opening 13b with an inner diameter _{D 1} (through It is a member formed in a tubular shape whose inner diameter of the circular tube is gradually reduced. In the present embodiment, as an example, as shown in FIG. 7, a shape in which the inner diameter of the tube is reduced at a constant rate and the inner surface of the tube is conical is employed.
Electromagnetic shield 13 is, together with the central axis of the inner peripheral surface is aligned with the center axis O ₁ of the induction heating coil 7 is arranged at a position covering the lower end side of the coil winding of the lower coil portion 7B from the lower side, the outer The part is supported by the electromagnetic shield support member 6 extended from the induction heating coil support part 8.
In the present embodiment, the electromagnetic shield 13 is disposed closer to the induction heating coil 7 than the middle between the induction heating coil 7 and the mold 4, and is closer to the induction heating coil 7 than the mold 4.

According to the centrifugal casting apparatus 1B, centrifugal casting can be performed as in the first embodiment.
A magnetic field generated by the induction heating coil 7 when performing induction heating enters the electromagnetic shield 13 and is trapped.
For this reason, the temperature rise of the metal mold | die 4 can be suppressed similarly to the said 1st Embodiment, and the fall of a cooling rate can be reduced.

  In addition, according to the centrifugal casting apparatus 1B, the electromagnetic shield 13 has a shape that covers the lower side of the lower coil portion 7B and also covers the side, and is thus disposed horizontally below the induction heating coil 7. Compared with the electromagnetic shield 5 of the first embodiment, the magnetic force lines generated on the outer peripheral side of the lower coil portion 7B can be more efficiently penetrated. For this reason, the magnetic field generated by the lower coil portion 7B can be easily confined in the vicinity of the lower coil portion 7B, and the magnetic flux leaking to the mold 4 can be further reduced.

Moreover, since the electromagnetic shield 13 covers the lower end portion and the side of the lower coil portion 7B, when the molten metal 10 that has fallen to the molten metal injection port 4a jumps up, the high-temperature molten metal 10 that has jumped up becomes lower coil. It has a function of a protective member for preventing the portion 7B from adhering.
That is, when the molten metal 10 that jumps up on the surface of the lower coil portion 7B adheres, the adhered molten metal 10 is subjected to induction heating and remelted, and a hole is made in the surface of the lower coil portion 7B, so that the refrigerant leaks. There is a risk of release. In the present embodiment, the molten metal 10 that has bounced up is blocked by the electromagnetic shield 13 and does not adhere to the lower coil portion 7B, so that such a problem can be prevented.

[First Modification]
Next, a first modification of the present embodiment will be described.
FIG. 9 is a schematic cross-sectional view showing the main part of a centrifugal casting apparatus according to a first modification of the third embodiment of the present invention.

As shown in FIG. 9, the centrifugal casting apparatus 1 </ b> C of this modification includes an electromagnetic shield 13 </ b> A instead of the electromagnetic shield 13 of the third embodiment. Hereinafter, a description will be given focusing on differences from the third embodiment.
The electromagnetic shield 13A is provided with a low permeability layer 13c on the outer peripheral side surface of the electromagnetic shield 13 of the third embodiment.
The material of the low magnetic permeability layer 13c can be the same material as that of the low magnetic permeability layer 11 of the second embodiment.

  According to this modification, the electromagnetic shield 13A includes the electromagnetic shield 13 on the inner peripheral side and the low magnetic permeability layer 13c on the outer peripheral side, so that the electromagnetic shield 13 and the mold are compared with the third embodiment. 4 can be separated magnetically. For this reason, the electromagnetic shield 13A and the induction heating coil 7 can be brought closer to the mold 4 side. Therefore, for the same reason as described in the second embodiment, the chamber 2 can be downsized and the molding efficiency can be improved as compared with the third embodiment.

  Moreover, it is preferable to employ ceramics having heat resistance such as alumina, aluminum nitride, silicon carbide, boron nitride, and silicon nitride as the low magnetic permeability layer 13c. In this case, even if the high-temperature molten metal 10 that jumps up adheres to the low magnetic permeability layer 13c, heat is not easily transmitted to the electromagnetic shield 13, so the electromagnetic shield 13 does not melt and the durability of the electromagnetic shield 13A is improved. can do.

[Second Modification]
Next, a second modification of the present embodiment will be described.
FIG. 10: is typical sectional drawing which shows the principal part of the centrifugal casting apparatus which concerns on the 2nd modification of the 3rd Embodiment of this invention.

As shown in FIG. 10, the centrifugal casting apparatus 1D of the present modification has a low magnetic permeability layer 11 and an electromagnetic shield 12 on the mold 4 of the third embodiment as in the second embodiment. Is fixed. Hereinafter, a description will be given focusing on differences from the third embodiment.
According to this modification, in the centrifugal casting apparatus 1B of the second embodiment, since the electromagnetic shield 13 is further provided, the mold 4 is more reliable than the second and third embodiments. Shielded electromagnetically.
And by providing the electromagnetic shield 13, it can prevent adhering to the lower coil part 7B, even if the molten metal jumps up similarly to the said 3rd Embodiment.

[Fourth Embodiment]
Next, a centrifugal casting apparatus according to the fourth embodiment of the present invention will be described.
FIG. 11: is typical sectional drawing which shows the structure of the centrifugal casting apparatus which concerns on the 4th Embodiment of this invention. Fig.12 (a) is D view in FIG. FIG.12 (b) is D view in FIG. 11 at the time of rotation of a metal mold | die.

  As shown in FIGS. 11 and 12A, the centrifugal casting apparatus 1E of the present embodiment is similar to the centrifugal casting apparatus 1A of the second embodiment in that an electromagnetic shield plate 15 (electromagnetic shield) and a shield retracting mechanism 16 are used. (Shield moving mechanism). Hereinafter, a description will be given focusing on differences from the second embodiment.

The electromagnetic shield plate 15 is made of the same material as the electromagnetic shield 12 and is a disc member having an outer diameter D ₄ (where D ₄ > D ₁ ), and the side portion is connected to the shield retracting mechanism 16.
The shield retracting mechanism 16 has a position where the electromagnetic shield plate 15 is disposed on the electromagnetic shield 12 fixed to the mold 4 so as to cover the entire through-hole 12a (hereinafter referred to as a first position), and a radial direction. It moves between a position (hereinafter referred to as a second position) where the entire through-hole 12a is opened by retracting to the outside.

In the present embodiment, the schematic configuration of the shield retracting mechanism 16 is such that the rotating support shaft 16c fixed to the mold 4 and protruded upward from the electromagnetic shield 12 can be rotated on the electromagnetic shield 12 by the rotating support shaft 16c. And an L-shaped arm 16a disposed at one end of the electromagnetic shield plate 15 and having the other end disposed radially outside the electromagnetic shield 12 and the mold 4, and fixed to the other end of the L-shaped arm 16a. And a coil spring 16f that applies a moment about the rotation support shaft 16c in a direction in which the weight 16b approaches the side surface of the mold 4.
Further, a stud 16d that locks one end of the coil spring 16f is provided upright on the L-shaped arm 16a between the rotation support shaft 16c and the weight 16b.
Further, on the mold 4, a stud 16 e that locks the other end of the coil spring 16 f and a stopper 16 g that restricts the position of the L-shaped arm 16 a that receives a moment from the coil spring 16 f in the rotational direction, respectively. And is provided in a state of protruding upward from the electromagnetic shield 12.
As shown in FIG. 12A, the position of the stopper 16g is such that when the rotation of the mold 4 is stopped, the stopper 16g receives a moment from the coil spring 16f and rotates clockwise in the figure. The electromagnetic shield plate 15 that regulates the position and is fixed to the L-shaped arm 16a is provided so as to be positioned at the first position.

  According to the centrifugal casting apparatus 1E, while the rotation drive unit 3 is stopped and the rotation of the mold 4 is stopped, the electromagnetic shield plate 15 is positioned at the first position as shown in FIG. Is done. As a result, the entire through-hole 12 a is covered with the electromagnetic shield plate 15. Therefore, since the mold upper surface 4d of the mold 4 is covered with either the electromagnetic shield 12 or the electromagnetic shield plate 15 including the melt inlet 4a, the entire upper surface side of the mold 4 is electromagnetically shielded. Yes.

On the other hand, when the rotation drive unit 3 is driven and rotation of the mold 4 is started, centrifugal force F acts on the weight 16b as shown in FIG. This centrifugal force F causes the counterclockwise moment shown in the figure to act on the L-shaped arm 16a with respect to the rotating support shaft 16c. The L-shaped arm 16a rotates. Here, the coil spring 16f constitutes an urging means for urging the weight 16b radially inward against the centrifugal force acting on the weight 16b during rotation.
Therefore, by appropriately setting the spring constant of the coil spring 16f, the electromagnetic shield plate 15 can be moved to the second position when the mold 4 reaches a certain rotational speed.
Therefore, the molten metal 10 can be passed through the through-hole 12a.
Moreover, if the rotation drive part 3 is stopped and rotation of the metal mold | die 4 is stopped, the electromagnetic shielding board 15 will move to a 1st position with the elastic restoring force of the coil spring 16f.

In order to perform casting with the centrifugal casting apparatus 1E, first, the molten metal 10 is formed by performing induction heating of the metal material in a state where the rotation driving unit 3 is stopped.
At this time, since the entire upper surface side of the mold 4 is electromagnetically shielded, it is possible to reliably prevent the magnetic lines of force from entering the mold 4 through the molten metal inlet 4a. As a result, the temperature rise of the mold 4 due to induction heating can be reliably prevented.
Next, when the molten metal 10 reaches the vicinity of the molding start temperature, the rotation driving unit 3 starts to rotate and the mold 4 is rotated. When the mold 4 reaches a certain number of revolutions, the electromagnetic shield plate 15 moves to the second position, so that the upper part of the through-hole 12a is opened.
When the molten metal 10 reaches the molding start temperature and the upper part of the through-hole 12a is opened, induction heating is stopped and the molten metal 10 is dropped.
Hereinafter, similarly to the second embodiment, after the molten metal 10 is solidified, the molded product can be removed.

According to the centrifugal casting apparatus 1E, the temperature increase of the mold 4 due to the leakage of magnetic flux during induction heating can be further suppressed as compared with the second embodiment, so that the decrease in the cooling rate can be further reduced. it can.
Further, since the shield retracting mechanism 16 moves the electromagnetic shield plate 15 by the centrifugal force acting on the weight 16b as the mold 4 rotates, the shield retracting mechanism 16 needs to have a dedicated power source and control means. There is no. This simplifies the apparatus configuration.
Further, in the centrifugal casting apparatus 1E, for example, even if the metal material fails to be inductively floated due to troubles of the apparatus, and the metal material or the molten metal in the middle of heating falls, the electromagnetic shield plate 15 causes these metal materials or The molten metal in the middle of heating does not enter the molten metal inlet 4a. For this reason, since it is not necessary to clean the inside of the metal mold | die 4 or to reset the metal mold | die 4, it becomes easy to redo shaping | molding.

In the description of the first embodiment, the electromagnetic shield 5 is a region radially outward from the smallest coil inner periphery on the mold 4 side when viewed from the direction along the central axis O ₁ (see FIG. together provided radially outward) than circle C ₁ of 3, described in the example in which the electromagnetic shield 5 is provided in the radially inner region than the inner circumference of the smallest coil of the mold 4.
Electromagnetic shield 5, at least when viewed from the direction along the center axis O _1, if positioned radially outer region than the peripheral within the smallest coil of the die 4 side due to the lower coil section 7B Magnetic field lines can penetrate the electromagnetic shield 5. Therefore, it may be an inner diameter D ₁ of the through-hole 5a as a configuration in which greater than the inner diameter D _B of the inner periphery of the smallest coil of the mold 4.
The electromagnetic shield 5, when viewed from the direction along the center axis O _1, the maximum outer diameter D _max of the induction heating coil 7 to the outer diameter, the inner periphery of the smallest coil of the die 4 side inner diameter D _B More preferably, it is provided in a range that overlaps the ring-shaped region having an inner diameter.
The same applies internal diameter D ₁ of the through hole 12a in the other embodiments.

  In the description of the first embodiment, the electromagnetic shield 5 has been described as an example in which the shape of the electromagnetic shield 5 is an annular shape. However, the electromagnetic shield 5 is a perforated plate having a polygonal inner periphery and outer periphery. May be. In this case, it is more preferable if the polygonal shape is rotationally symmetric with respect to the central axis.

In the third embodiment, the example in which the pipe inner diameter of the electromagnetic shield 13 is reduced at a constant rate has been described. However, the ratio of the reduced diameter may be changed in the axial direction.
Moreover, the tube shape of the electromagnetic shield 13 is not limited to a shape whose diameter is reduced downward in the axial direction, and an appropriate cross-sectional shape that covers the lower side and the side of the lower end portion of the induction heating coil 7 is adopted. Can do.
Further, the electromagnetic shield 13 may be a bottomed tubular member having a bottom surface on the lower side, and a shape in which a through hole is provided at the center of the bottom surface to form the lower opening 13b.
Further, in FIG. 7, the electromagnetic shield 13 is drawn so as to cover the side of the lowermost coil winding of the lower coil portion 7B, but the upper opening 13a is further extended upward to form a plurality of steps. It is good also as a shape which covers the side of this coil winding. As long as the measurement by the radiation thermometer 9 is not disturbed, it may be provided in a shape that covers the entire side of the lower coil portion 7B.

  In the description of the second modification of the third embodiment, the centrifugal casting apparatus 1D has been described as an example in which the electromagnetic shield 13 and the electromagnetic shield 12 are provided. When the shielding effect is obtained, the electromagnetic shield 13 may be replaced with a member formed of a material having a low relative permeability, and may simply be a protective member that protects the lower coil portion 7B from the splash of the molten metal 10.

In the description of the fourth embodiment, the example in which the rotation of the mold 4 is stopped at the start of induction heating has been described. However, the electromagnetic shield plate 15 acts on the weight 16b to cause the electromagnetic shield plate 15 to pass through the through-hole 12a. Alternatively, the mold 4 may be rotated at a speed that does not deviate from the position where the electromagnetic shield is covered, and the electromagnetic shield plate 15 may be moved to the second position by accelerating the rotation immediately before finishing the induction heating.
Moreover, when the moving time from the first position to the second position can be made shorter than the dropping time of the molten metal 10, the induction heating is finished and the rotation is started or accelerated at the same time. Good.

  In the description of the fourth embodiment, the example in which the weight 16b moves along the radially outer side and the circumferential direction by rotating and moving by centrifugal force has been described. However, the weight 16b and the coil spring 16f are replaced with each other. It is good also as a structure arrange | positioned along the radial direction on the metal mold | die 4, and the weight 16b and the electromagnetic shielding board 15 slide-moving along a radial direction.

In the description of the fourth embodiment, the shield retracting mechanism 16 is an example in which the electromagnetic shield plate 15, which is a part of the electromagnetic shield, moves so as to retract from the molten metal inlet 4 a of the mold 4. explained.
However, the shield moving mechanism is configured to move all of the electromagnetic shield arranged between the mold and the induction heating coil in the radial direction of the induction heating coil with respect to the mold and retract from the mold. Also good.
For example, in the first embodiment, the electromagnetic shield 5 is replaced with a disk-shaped electromagnetic shield from which the through-hole 5 a is deleted, and the electromagnetic shield is replaced with the electromagnetic shield support member 6 in the radial direction of the induction heating coil 7. A manipulator for advancing and retreating may be provided as a shield moving mechanism, and the entire electromagnetic shield may be retracted from the molten metal inlet 4a by the shield moving mechanism immediately before the molten metal 10 is dropped. In addition, it is more preferable to make the outer diameter of the electromagnetic shield coincide with the outer diameter of the mold 4 because the entire mold 4 can be electromagnetically shielded as in the fourth embodiment.

  In the above description of each embodiment, the induction heating coil 7 is an induction floating heating coil. However, the induction heating coil that does not float the molten metal is used to form the molten metal in the crucible and start forming. It is good also as a structure which drops the molten metal which reached temperature from a crucible.

  In addition, all the constituent elements described in the above embodiments and modifications can be implemented in appropriate combination within the scope of the technical idea of the present invention.

DESCRIPTION OF SYMBOLS 1, 1A, 1B, 1C, 1D, 1E Centrifugal casting apparatus 3 Rotation drive part 4 Mold 4a Molten metal injection port 4c Cavity 4d Mold upper surface 5, 12, 13, 13A Electromagnetic shield 5a, 12a Through-hole 7 Induction heating coil 7A Upper coil part 7B Lower coil part 10 Molten metal 11, 13c Low magnetic permeability layer 11a Through-hole 13b Lower-side opening (through-hole)
15 Electromagnetic shield plate (electromagnetic shield)
16 Shield retraction mechanism (shield movement mechanism)
16b spindle 16f coil spring F the centrifugal force _{M 1, M 2, M 3} , M 4 field lines _{O 1} the center axis _{O 2} rotation axis

Claims (8)

An induction heating coil for obtaining a molten metal by electromagnetic induction heating of a metal material;
A mold for injecting the molten metal to perform casting and a molten metal inlet for injecting the molten metal into the cavity, and a mold in which the molten metal inlet is disposed below the induction heating coil;
An electromagnetic shield provided between the induction heating coil and the mold,
The electromagnetic shield is provided at least in a region radially outside the smallest coil inner circumference on the mold side of the induction heating coil as viewed from the direction along the central axis of the induction heating coil. Centrifugal casting equipment. The induction heating coil is an induction floating heating coil that induces and floats the molten metal,
The electromagnetic shield is provided in a region radially inward from the inner circumference of the coil when viewed from the direction along the central axis of the induction heating coil, and has a through-hole through which the molten metal passes. The centrifugal casting apparatus according to claim 1. The centrifugal casting apparatus according to claim 1, further comprising a shield moving mechanism that moves an arrangement position of at least a part of the electromagnetic shield in a radial direction of the induction floating coil with respect to the mold. The centrifugal casting apparatus according to any one of claims 1 to 3, further comprising a low permeability layer having a relative permeability lower than that of the electromagnetic shield between the electromagnetic shield and the mold. . The centrifugal casting apparatus according to claim 4, wherein the electromagnetic shield is fixed on the mold through the low magnetic permeability layer. The centrifugal casting apparatus according to claim 4, wherein the low magnetic permeability layer has a heat insulating layer that suppresses heat transfer from the electromagnetic shield. The centrifugal casting apparatus according to claim 2, wherein the electromagnetic shield is disposed closer to the induction heating coil than an intermediate between the induction heating coil and the mold. The centrifugal casting apparatus according to claim 7, wherein a low permeability layer having a lower relative permeability than that of the electromagnetic shield is provided on the mold side of the electromagnetic shield.

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