JPH10202356A - High frequency induction vacuum casting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high frequency induction vacuum casting apparatus which can introduce in a low cost. SOLUTION: A crucible 7 providing a copper pipe 15 in a case 1 is arranged and a mold 31 is inserted into an insert recessed part 17 in a supporting base member 19. A suction tube 21 is fitted to the supporting base member 19 so as to open a hole at the bottom surface part 23 in the insert recessed part 17, and a vacuum pump 27 is connected with the suction tube 21. An insert plug 39 is connected with an AC 100 V electric source for commerce to make the apparatus under working state.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting apparatus for casting a molded article of a noble metal such as a ring from a metal material.

[0002]

2. Description of the Related Art In order to cast small noble metal and small dental metal, first, a solidified metal material (metal) must be heated and melted. Usually, the ingot is heated and melted by storing the ingot in a crucible around which a high-frequency heating coil is wound and applying a high-frequency alternating current to the high-frequency heating coil to generate an eddy current in the ingot. The molten metal obtained by melting the metal is filled into the molding cavity of the mold and molded, but the inside of the mold is evacuated using a vacuum pump to spread the molten metal to every corner of the molding cavity. Often.

[0003]

In a high-frequency vacuum casting apparatus equipped with a crucible wound with a high-frequency heating coil and a vacuum pump, a large alternating current is applied to the high-frequency heating coil to melt the metal in a short time. In addition, since a high-voltage power supply (power supply such as 200 V AC) is used to strongly evacuate the inside of the mold using a vacuum pump having a large suction force, the introduction cost of the apparatus is increased.

Therefore, an object of the present invention is to provide a high-frequency vacuum casting apparatus which can be introduced at a low cost.

[0005]

In order to achieve this object, a high-frequency vacuum casting apparatus according to the present invention comprises a case, a crucible for containing a metal material accommodated in the case, and an outer periphery of the crucible. A high-frequency heating coil for melting the metal material accommodated in the crucible, and a mold having a molding cavity that is housed in the case and filled with the metal material melted in the crucible, A high-frequency vacuum casting apparatus comprising: a support base member having a fitting recess in which the mold is fitted; and suction means provided with a suction pipe communicating with the inside of the mold fitted to the support base member. Further, an AC 100 V power supply is used as a power supply for the high-frequency heating coil and the suction means. Since this high-frequency vacuum casting apparatus can use commercial power, it can be introduced and used in ordinary households and small offices. Commercial AC100V
Since the frequency of the power supply is 50/60 Hz (low frequency), a frequency converter (preferably a vacuum tube oscillator) is connected between the high-frequency heating coil and a commercial AC 100 V power supply to reduce the frequency of the alternating current flowing through the high-frequency heating coil. 10kHz
To 500 kHz. Normally, a support base member of the suction means is arranged in the case, and a suction pipe opening to the fitting recess of the support base member extends outside the case and is connected to a vacuum pump. When the vacuum pump is driven, the fitting recess side of the support base member is sucked through the suction pipe, and in this fitting recess, a mold formed to have air permeability in many cases is fitted and supported. Therefore, the inside of the mold cavity of the mold is sucked. The mold is usually placed in the case in an upright state, that is, with the sprue positioned upward and the lower side fitted and supported in the fitting recess of the support base member.
The crucible is also usually placed in the case in an upright state, that is, with the opening positioned upward, but the opening is close to the gate of the mold so that the molten metal can be poured into the gate. It is configured to be tiltable.

[0006] The fitting recess is usually formed of a bottom portion and a peripheral wall portion, and the lower side of the mold is usually fitted and supported in the peripheral wall portion so that the lower surface abuts on the bottom portion. Normally, the suction tube is opened at the center of the bottom of the fitting recess to suck the inside of the mold cavity from the lower surface, and if a large vacuum pump using a high voltage is used, the lower portion of the mold and the fitting recess are removed. Although the inside of the molding cavity can be sufficiently evacuated even if the hermeticity between them is somewhat low, if a vacuum pump with a weak suction power using a commercial AC100V power supply is used, the lower side of the mold is required. The vacuum cannot be satisfactorily vacuumed unless the seal between the part and the fitting recess is sufficiently secured, more specifically, the sealing between the lower surface of the mold and the bottom of the fitting recess. It may not reach the end in the cavity. In order to ensure sufficient sealing between the lower surface of the mold and the bottom portion of the fitting recess, an irregular fitting shape may be formed between the lower surface of the mold and the bottom portion of the fitting recess. For example, a convex portion may be formed on the lower surface of the mold, and a concave portion into which the convex portion fits may be formed at the bottom of the fitting concave portion. However, such a configuration makes the molding operation of the mold extremely difficult. Therefore, an inner taper is formed at the connection point between the bottom portion and the peripheral wall portion of the fitting recess, and an outer taper is formed on the outer periphery of the lower surface of the mold so as to abut the inner taper to enhance the sealing between the mold and the fitting recess. Is a good idea. The contact surface between the lower surface of the mold and the bottom portion of the fitting recess is bent at the tapered portion, so that the sealing performance can be improved.

When a large alternating current is applied to a high-frequency heating coil using a high-voltage power supply, large Joule heat is generated in the metal material in the crucible.
When a current of 15 A or 20 A is passed using a power supply, the metal material cannot be sufficiently melted in a short time unless the crucible shape is designed to improve the heating efficiency.
In order to improve the heating efficiency, first, it is necessary to increase the inner diameter of the crucible to increase the area of the metal accommodated in the crucible. In addition, it is necessary to ensure good heat conduction by adjusting the electromagnetic stirring force acting on the metal material in the crucible. Therefore, when the crucible is filled with a solidified metal material in order to obtain a molten metal material to be filled in the molding cavity of the mold, the upper end position of the solidified metal material is set to be less than half the crucible height. preferable. The predetermined amount of solidified metal material contained in the crucible has a low height and therefore a large area. The direction of the electromagnetic stirring force is reversed between the upper side and the lower side, with the center in the height direction of the crucible as the sakai. Therefore, if the metal material is half or less of the crucible height, uniform and efficient heating is possible because there is no possibility that a stirring force in which directions are reversed in the upper and lower sides acts on the metal material in the crucible. .

[0008]

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

FIG. 1 is a view showing the entire configuration of a high-frequency vacuum casting apparatus according to the present invention.

The case 1 comprises a case body 3 having a circular cross section and a lid 5 for sealingly closing the top opening of the case body 3, and a crucible 7 having an upper surface opening is disposed inside the case body 3. ing. In the crucible 7, a mounting portion 11 protruding downward from the lower surface 9 is rotatably mounted on a distal end portion of a rod-shaped support member 13 extending in a horizontal direction from an upper portion of the inner peripheral surface of the case body 3, and can be tilted or rocked. The copper tube coil 15 (high-frequency heating coil) is wound around the outer periphery (see also FIG. 2). Case body 3
A support base member 19 having a fitting recess 17 of an upper surface opening is fixed to the inner bottom surface, and a suction tube 21 extends downward from the support base member 19. The upper end of the suction tube 21 penetrates through the center of the support base member 19 and opens at the bottom portion 23 of the fitting recess 17. The lower side of the upper end of the suction tube 21 extends outward through the bottom of the case body 3. , A valve 25 and a vacuum pump 27. Support base member 1
The lower part of a mold 31 (for lost wax) having a sprue portion 29 formed on the upper surface thereof is fitted into and supported by the fitting recess 17 of 9. The mold 31 is connected to the sprue portion 29 and is used for a ring. A plurality of molding cavities 33 are configured. In the drawing, reference numeral 35 denotes an air intake pipe to which the electromagnetic valve 37 is connected, 39 denotes a plug inserted into a commercial AC 100 V power supply, and 41 denotes a viewing window.

In order to cast a ring, first, a base metal 43 such as gold or platinum is accommodated in the crucible 7 with the lid 5 opened, and the lid 5 is closed. As shown in detail in FIG.
3 is formed in a chip shape, and the chip-shaped metal 4
3 is accommodated in the crucible 7 as long as a molten metal filling the molding cavity 33 of the mold 31 is obtained (FIG. 2 is a diagram showing details of the crucible 7). Since the inner diameter of the crucible 7 is large, the upper ends of the chip-shaped base metals 43 stacked in the crucible 7 are located slightly below the center of the crucible 7 in the height direction. Next, an electric current is applied to the copper tube coil 15 to melt the metal 43. When the metal 43 is melted, the vacuum pump 27 is driven and the case 1 is opened via the valve 25 and the mold 31 in the open state.
The inside has been evacuated. When the bullion 43 melts,
As shown in FIG. 3, the crucible 7 is tilted and the molten metal is
The molten metal that has flowed into the sprue portion 29 of the first sprue portion 29 is sucked by the vacuum pump 27 and filled into the molding cavity 33 (FIG. 3 is a diagram showing the tilted state of the crucible 7). At the same time as the crucible 7 is tilted, the electromagnetic valve 37 opens, and air is drawn into the case 1 from the air suction pipe 35. An inner taper 47 is formed at a connection point between the bottom surface portion 23 and the peripheral wall surface portion 45 of the fitting recess 17, and an outer taper 49 is formed on the outer periphery of the lower end of the mold 31 so as to abut the inner taper 47. The degree of sealing between the bottom (lower surface) of the mold 31 and the bottom portion 23 of the fitting recess 17 is high, and the vacuum pump 27
To effectively prevent the case 1 from being evacuated. The inclination of the inner taper 47 and the outer taper 49 is 30 to 60 degrees (preferably 45 degrees),
The length is 2.5 mm to 4.5 mm (preferably 3.0 m
m to 4.0 mm). The inner taper 47 and the outer taper 49 have the same inclination and the same length.

[0012]

As described above, the high-frequency vacuum casting apparatus of the present invention can reduce the cost of the apparatus itself,
In addition, other introduction costs are low.

[Brief description of the drawings]

FIG. 1 is a view showing the entire configuration of a high-frequency vacuum casting apparatus according to the present invention.

FIG. 2 is a diagram showing details of a crucible.

FIG. 3 is a diagram illustrating a tilted state of a crucible.

[Explanation of symbols]

 Reference Signs List 1 case 7 crucible 15 copper tube coil (high-frequency heating coil) 17 fitting recess 19 support base member 21 suction tube 31 mold 33 molding cavity

Claims (4)

[Claims] 1. A case and a case contained in the case.
A crucible for accommodating the metal material, a high-frequency heating coil wound around the outer periphery of the crucible and melting the metal material accommodated in the crucible, and housed in the case and melted in the crucible A mold having a molding cavity filled with the metal material, and a support base member having a fitting recess into which the mold is fitted, and communicating with the inside of the mold fitted into the fitting recess of the support base member. A high-frequency vacuum casting apparatus comprising: a suction unit provided with a suction tube; and A is a power supply for the high-frequency heating coil and the suction unit.
A high-frequency vacuum casting apparatus using a C100V power supply. 2. The fitting recess of the support base member,
It is formed from a bottom part and a peripheral wall part, and an inner taper is formed at a connection point between the bottom part and the peripheral wall part,
The high-frequency vacuum casting apparatus according to claim 1, wherein an outer taper is formed on an outer periphery of an end portion of the mold so as to be in contact with the inner taper. 3. A case and a case accommodated in the case.
A crucible having an open upper surface for accommodating a solidified metal material, a high-frequency heating coil wound around the outer periphery of the crucible for melting the solidified metal material contained in the crucible, and tilting the crucible An inclining means, a gas-permeable mold formed in the case and having a sprue on the upper surface for receiving a molten metal material flowing out of the crucible tilted, and a molding cavity formed with a molding cavity connected to the sprue; A support base member formed with a fitting recess into which a side portion is fitted; a suction pipe connected to the support base member, communicating with the inside of the mold supported by being fitted into the fitting recess; and connected to the suction pipe. A vacuum pump, comprising: a fitting portion of the support base member, wherein the fitting recess is formed from a bottom surface portion and a peripheral wall surface portion; A high-frequency vacuum casting apparatus, wherein an inner taper is formed at a connection point with a peripheral wall portion, and an outer taper is formed on an outer periphery of a lower end portion of the mold so as to contact the inner taper. 4. The crucible according to claim 1, wherein when the molten metal material is contained in the molding cavity of the mold to receive the molten metal material, an upper end position of the metal material is less than half the crucible height. 4. The high-frequency vacuum casting apparatus according to claim 1, wherein the housing portion has a large diameter.