JPH08155629A - Casting device with induction coil and induction coil - Google Patents

Abstract

PURPOSE: To provide a casting device advantageous to the improvement in the durability of an induction coil and extention in the service life of the same by avoiding the oxidation of the induction coil by a high temperature. CONSTITUTION: In a casting device equipped with a die 1 with a cavity for forming a product, a molten metal container holding molten metal, a stoke 28 supplying the molten metal to the cavity of the die 1, and an induction coil arranging chamber 20, an induction coil 3 winding almost coaxially around the stoke 28 is provided. A heat insulating sleeve 5 is almost coaxially arranged between the induction coil 3 and the stoke 28, and through-holes 21 and 22 supplying outdoor air to the induction coil arranging chamber 20. The induction coil 3 is constituted by laminating gold-plated layer and ceramics layer successively on a coil main body 30 made of a copper pipe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a casting device having an induction coil and an induction coil. The present invention can be applied to, for example, a low pressure casting device, a gravity casting device, and a high pressure casting device.

[0002]

2. Description of the Related Art Conventionally, a gas burner method or an electric resistance heater method has been adopted as a mode for heating a mold or the like in a casting apparatus. However, the gas burner method has a problem that the working environment is deteriorated by the exhaust gas after the combustion gas is burned. Further, there is a problem that soot and carbon monoxide are generated due to incomplete combustion. More stable Hi-
Temperature control by Lo control is difficult. Further, according to the electric resistance heater method, since electricity is used as power, there are advantages that unnecessary exhaust gas is not generated, temperature adjustment is easy, and the like. However, it is not always sufficient for use in a casting machine.

Further, a method of induction heating with an induction coil can be considered. However, the induction coil has a problem that it tends to be oxidized at a high temperature when the ambient temperature is high. High temperature oxidation is disadvantageous in ensuring the required performance of the induction coil.
Further, the oxide layer obtained by oxidizing the surface layer of the induction coil gradually comes off as the usage period becomes longer. In this case, the problem of short circuit in the induction coil arises via the oxide layer that has come off.
Further, the induction coil may come into contact with the machine die base of the casting apparatus via the peeled oxide layer to cause electric leakage.

A technique for cooling the induction coil with cooling water has also been conventionally disclosed (Japanese Utility Model Laid-Open No. 6-34858). According to this, the temperature rise of the induction coil can be suppressed.

[0005]

However, water cooling of the induction coil may be disadvantageous. For example, FIG. 6 shows an example in which an induction coil is applied to a low pressure casting device. In FIG. 6, molten metal 1
A stalk 104 as a hot water supply pipe is immersed in a holding container 102 such as a furnace holding 00, and an induction coil 106 is arranged around the stalk 104 substantially coaxially. Then, air is supplied from the pressurizing port 102a to hold the holding container 102.
The atmospheric pressure is increased to push up the molten metal in the stalk 104, and the pushed molten metal is supplied to the cavity of the mold. As can be understood from FIG. 6, in the low-pressure casting apparatus, the molten metal 100 is formed below the induction coil 106.
Is located. Therefore, cooling the induction coil 106 with cooling water is not preferable because it may induce a steam explosion.

In such a case, the induction coil 106 is likely to reach a high temperature due to heat radiation or heat conduction. Therefore, with use, high-temperature oxidation of the induction coil 106 is likely to occur. The present invention has been made in view of the above circumstances, the common problem of each claim, by avoiding the high temperature oxidation of the induction coil, the durability of the induction coil is improved, a casting device advantageous for long life, To provide an induction coil.

[0007]

A casting apparatus equipped with an induction coil according to the present invention comprises a mold having a cavity for forming a product, a molten metal container for holding molten metal, and a molten metal held in the molten metal container. In a casting apparatus including a hot water supply pipe having a hot water supply passage for supplying a metal mold to a mold cavity, and an induction coil placement chamber surrounding the hot water supply pipe, the casting device is held in the induction coil placement chamber and wound around the hot water supply pipe. An induction coil,
A heat insulating member arranged between the induction coil and the hot water supply pipe; and gas supply means for supplying a cooling gas to the induction coil arrangement chamber to bring the cooling gas into contact with the induction coil in the induction coil arrangement chamber. It is characterized by that.

The induction coil of the present invention comprises a coil body made of a conductive material, a gold plating layer laminated on the outer surface of the coil body, and a ceramic layer laminated on the outer surface of the gold plating layer. It is a feature.

[0009]

According to the casting apparatus of the present invention, the molten metal held in the molten metal container is supplied to the mold cavity through the molten metal supply pipe. The molten metal supplied to the cavity is
It solidifies and becomes a product. When an alternating current is applied to the induction coil, an induction current flows through the molten metal of the hot water supply pipe, or an induction current flows through the hot water supply pipe when the hot water supply pipe is conductive. The temperature of the molten metal supplied to the cavity through the hot water supply pipe is maintained by the Joule heat accompanying the induced current.

The heat radiation and heat conduction from the molten metal at high temperature are suppressed by the heat insulating member, and the overheating of the induction coil is suppressed. Since the cooling gas sent from the gas supply means to the induction coil placement chamber contacts the induction coil, overheating of the induction coil can be suppressed in this sense as well. According to the induction coil of the present invention, since the gold plating layer is laminated on the coil body, direct contact between the coil body and air can be suppressed. Furthermore, since the gold plating layer has excellent thermal conductivity, local heat unevenness in the coil body is avoided.

[0011]

Embodiments of the present invention will be described below. In this example, water cooling of the induction coil is stopped and air cooling is performed.
The overall configuration according to this embodiment is basically the same as the configuration shown in FIG. FIG. 1 schematically shows a main part of a casting apparatus according to this embodiment. A mold 1 as a mold is fixed to a steel machine die base 2 of a casting device. Mold 1
Comprises a cavity forming a product. Below the mold 1, a molten metal container similar to the molten metal container 102 of the prior art shown in FIG. 6 is arranged. In the machine die base 2 located below the die 1, an induction coil placement chamber 20 is formed by being divided by a board 20x. A stalk 28 as a hot water supply pipe is vertically arranged so as to pass through the induction coil placement chamber 20. The stalk 28 is made of steel and has a hot water supply passage 28 t for supplying the aluminum-based molten metal of the molten metal container to the cavity of the mold 1. Stoke 28 in some cases
May be composed mainly of a refractory material or mainly composed of a refractory material.

The induction coil 3 is placed in the induction coil placement chamber 20.
Are arranged almost coaxially with the stalk 28. A heat insulating sleeve 5 as a heat insulating member is arranged between the induction coil 3 and the stalk 28 substantially coaxially. Therefore, heat transfer such as heat radiation from the stalk 28 to the induction coil 3 is
It can be suppressed. The heat insulating sleeve 5 is formed by binding an aggregate of ceramic fibers such as alumina with a binder.

The induction coil 3 is constructed by using a coil body 30 formed by winding a pipe made of a conductive material (eg, copper, copper alloy) into a coil shape. here,
The pipe diameter D1 of the pipe forming the coil body 30 is 6
About 10 mm, the coil diameter D2 of the coil body 30 is 1
The distance L1 between the coil portions that are vertically adjacent to each other is set to about 50 to 200 mm and about 3 to 10 mm. However, these values are appropriately changed according to the type of the casting apparatus and the like, and are not limited to the above values. In the present embodiment, the pipe hole 3 of the pipe forming the induction coil 3
The water cooling mode in which cooling water is supplied to f is abolished, and compressed air is sent to the pipe hole 3f from unillustrated pressure feeding means (for example, factory air source, compressor, pump, etc.), whereby the induction coil 3 is forcedly air-cooled. There is.

When a high frequency current is applied to the induction coil 3, an alternating magnetic flux is generated, which causes an induction current in the stalk 28 and the molten metal in the stalk 28, and the stalk 28 and the molten metal in the stalk 28 are heated by induction. It If the positional relationship between the induction coil 3 and the mold 1 is prescribed, the mold 1
Induction heating can be expected. The machine die base 2 has through holes 21, 2 for communicating the induction coil placement chamber 20 with the outside air.
2 is formed. The through hole 21 is the induction coil placement chamber 2
On the upper side of 0, the through hole 22 is located on the lower side of the induction coil placement chamber 20. This is for ensuring the heat convection in the vertical direction by utilizing the through holes 21 and 22 and discharging the hot air in the induction coil placement chamber 20 to the outside. The through holes 21 and 22 function as gas supply means for supplying outside air to the induction coil placement chamber 20. A plurality of upper through-holes 21 are formed because they easily function as exhaust holes due to thermal convection. A plurality of through holes 22 may also be formed.

As shown in FIGS. 2 and 3, a gold plating layer 33 is laminated on the entire area of the coil body 30 which constitutes the induction coil 3. The gold plating layer 33 is coated by electroplating. The thickness of the gold plating layer 33 can be appropriately selected, but can be set to, for example, about 0.5 μm or more. Due to the electroplating treatment, the inner surface of the pipe hole 3f of the coil body 30 is also covered with the gold plating layer 33. However, considering the price and the like, the gold plating layer 33 may not be coated on the inner surface of the pipe hole 3f by masking or the like.

According to the usual gold plating treatment, as a pretreatment, an intermediate plating layer such as nickel plating is laminated, and then gold plating treatment is performed to laminate the gold plating layer 33 to increase the strength of the gold plating layer 33. In the embodiment, in order to avoid high temperature oxidation of the intermediate plating layer of nickel or the like, the gold plating layer 33 is formed on the coil body 30 without stacking the intermediate plating layer.
Directly laminated to.

In order to increase the strength of the gold plating layer 33, the exposed surface of the coil body 30 is sandblasted as a roughening treatment before the gold plating treatment, and the gold plating layer 3
The adhesiveness of 3 was improved. Instead of sandblasting, shot or grid blasting may be performed. Although the gold plating layer 33 can prevent high-temperature oxidation of the coil body 30, the gold plating layer 33 has a problem that it is easily scratched. Further, in order to avoid a short circuit between pipes constituting the coil body 30 and an electric leakage, a ceramic layer 35 having a low thermal conductivity and a large electric resistance is laminated on the outer peripheral surface of the gold plating layer 33.

In this case, the procedure was as follows. That is,
A mixture of ceramic powder particles having low thermal conductivity and this heat-resistant paint, using a heat-resistant paint (Tyranno Coat: Ube Industries, Ltd.) containing a silicon-based binder (Tyranno polymer: Ube Industries, Ltd.) as a main component. Was applied to the gold-plated layer 33 by a brush coating method, and this was dried and fired (at 300 ° C. for 30 minutes) to form a ceramic layer 35. The mixture is not applied to the inner surface of the pipe hole 3f of the coil body 30.

In general, a material having a low thermal conductivity has a large electric resistance due to its physical properties, and a metal oxide corresponds to this. Therefore, as the ceramic powder particles, ZrO
₂ , SiO ₂ , TiO ₂ , Al ₂ O ₃ , MgO, CaO
It is preferable to use the single product or a composite oxide thereof. When the main chain of the polycarbosilane skeleton is a reticulated organosilicon polymer in which the main chain of the polycarbosilane skeleton is cross-linked, the above heat-resistant paint (tyrannocoat) is directly applied to the induction coil 3 to form a laminated film In addition, since the coating film starts to soften at about 300 ° C., the coating film may be broken when used alone. Further, since the Tyranno coat film can generally be made as thin as 0.1 to 0.3 mm, it is still easily scratched and its heat insulating property is not so large. However, since the above heat-resistant paint (Tyranno coat) has good adhesion and adhesiveness to the induction coil 3, the present inventor has considered using it as a binder. Therefore, in order to prevent scratches and to secure heat insulation, 70% to 90% of the above-mentioned ceramic powder particles are mixed with 10% to 30% of Tyranno coat in wt% to form a mixture to form the ceramic layer 35. .

In this example, the mixture was laminated by one brush application. Generally 0.3 to 0.
8mm coating can be secured, and by overcoating 1.5 ~
The thickness could be increased to 2.0 mm, and the ceramic layer 35 having heat insulation and durability could be formed. This thickness is not limited to the above value. If necessary, the mixing ratio of the Tyranno coat and the ceramic powder particles and the particle size of the ceramic powder particles can be selected. The means for laminating the mixture to form the ceramic layer 35 is not limited to brush coating, and can be appropriately changed by a spray method, a dipping method, or the like.

The mounting structure of the induction coil 3 is shown in FIG. As shown in FIG. 4, the mounting portion 3i of the induction coil 3 around which a pipe having a pipe hole is wound is provided with a holding hole 70a of a coil support 70 made of an electrically insulating material (for example, a sintered body such as silicon nitride or alumina). While fitting the coil holder 70 into the mounting hole 72h of the metal mounting board 72, the crimp terminal 74 made of steel is applied to the mounting board 72 in that state, and the bolt 76 made of steel is screwed on. As a result, the coil holder 70 is attached to the metal mounting board 72, and the induction coil 3
Is held on the mounting board 72. Therefore, the mounting board 72 functions as an induction coil holding means.

In this state, the power feeding line 39 functioning as a power feeding means is electrically connected to the induction coil 3 so that power can be fed from the power feeding device to the induction coil 3. In the present embodiment, the safety of the entire circuit is improved by applying the mixture even in the connection area between the induction coil 3 and the power supply line 39. By the way, conventionally, the ambient temperature of the space 20r of the induction coil placement chamber 20 is about 500 °.
It is about C, and the induction coil 3 becomes a high temperature due to heat radiation and heat conduction of the molten metal as described above. This is because it is affected by high-temperature molten metal in the stalk 28, heat radiation from the high-temperature stalk 28 itself, heat conduction and the like. Further, in the present embodiment, the water cooling mode of cooling the induction coil 3 is abolished and switched to the air cooling mode of cooling the induction coil 3, so that the space 20r of the induction coil placement chamber 20 is more likely to be heated. Therefore, in this embodiment, the heat load on the induction coil 3 is a severe condition.

Therefore, in this embodiment, as can be understood from FIG. 1, the heat insulating sleeve 5 is arranged between the stalk 28 and the induction coil 3 as described above, and the stalk 28 and the stalk 2 are arranged.
The heat conduction and the heat radiation from the molten metal of No. 8 are enhanced.
As a result, the ambient temperature of the space 20r outside the heat insulating sleeve 5 was lowered to about 350 ° C. Further, in this embodiment, through holes 21 and 22 are provided above and below the machine die base 2. Therefore, the heated air is easily exhausted from the upper through hole 21 due to the thermal convection phenomenon. When exhausted, fresh outside air having a low temperature enters the induction coil placement chamber 20 through the through hole 22 on the lower side, so that the induction coil placement chamber 20 is prevented from rising in temperature and outside air having a low temperature is fed to the induction coil 3. Since it is in contact with, it is possible to suppress the temperature rise of the induction coil 3.

As described above, in this embodiment, the through holes 21 and 22 are formed.
The ambient temperature of the space 20r outside the heat insulating sleeve 5 is about 30 by actively performing the heat convection phenomenon utilizing
Could be reduced to 0 ° C. Therefore induction coil 3
It is advantageous for suppressing high temperature oxidation and prolonging the service life. Further, in this embodiment, since the heat insulating sleeve 5 having a low magnetic permeability is arranged substantially coaxially with the induction coil 3, the heat insulating sleeve 5 and the induction coil 3 are substantially parallel to each other. Therefore, it is possible to prevent the heat insulating sleeve 5 from blocking the magnetic flux generated in the induction coil 3, which is advantageous for induction heating of the stalk 28 and the like.

In addition, the following effects can be expected in this embodiment. Since induction heating can now be applied to low-pressure casting and gravity casting under severe conditions, it is possible to maintain stable mold temperature conditions and molds in the casting equipment and the mold 1 where heat retention and heating are required. The temperature setting of can now be adjusted. As a result, it is possible to improve the quality (reduce the defect rate, eliminate the specific defect that has occurred conventionally).

Further, since the heating of the mold 1 can be achieved by the induction heating by the induction coil 3, by using the induction heating by the induction coil 3 and the preheating burner together in the mold preheating process before the start of the casting process, The preheating time of 1 was shortened by about 60%. Further, by utilizing the preheating of the coating mold for coating the mold 1, oxidation of the surface of the mold 1 can be suppressed, and the life of the coating mold applied to the cavity surface of the mold 1 can be reduced. I was able to double it. Through these measures, we were able to improve the operating rate.

(Other Embodiments) In this embodiment, the induction coil 3 is used.
As a countermeasure against the short circuit and the electric leakage, the coil body 30 made of a copper pipe is coated with a mixture of a heat-resistant paint (tyranno coat) and ceramic powder to form the ceramic layer 35, but the invention is not limited to this. A form in which a heat-resistant cement layer is laminated on the coil body 30 may be used. In some cases, a form in which a heat resistant resin layer is laminated may be considered. Even in this case, the gold plating layer 33 is effective.

Further, as in another embodiment shown in FIG. 5, an air supply device 81 for supplying a cooling gas to the induction coil arrangement chamber 20 of the machine die base 2 is provided and the induction coil arrangement chamber 20 is exhausted. The exhaust device 82 may be installed. The air supply device 81 and the exhaust device 82 can improve the release of hot air from the induction coil placement chamber 20, and can further contribute to the prevention of high-temperature oxidation of the induction coil 3. As the cooling gas, air, or an inert gas such as nitrogen or argon gas can be used in some cases. Use of an inert gas can further contribute to prevention of high temperature oxidation of the induction coil 3. Air supply device 81 and exhaust device 82
Also functions as a gas supply unit that supplies the cooling gas to the induction coil placement chamber 20. At least one of the air supply device 81 and the exhaust device 82 may be provided.

Further, in addition to the heating conditions by the induction coil 3, if the cooling conditions by the cooling gas through the through passages 21 and 22 are appropriately combined, it becomes possible to perform fine mold temperature control. The induction coil 3 described above is
The present invention can be applied not only to the casting device used for low pressure casting but also to a gravity casting device, a high pressure casting device and the like. Further, it can be applied to a heat treatment apparatus such as an induction hardening apparatus that uses induction heating, a welding apparatus that uses induction heating, and a hot forging apparatus.

Besides, the present invention is not limited to the embodiments described above and shown in the drawings. For example, the molten metal is not limited to aluminum type, but can be applied to cast iron, cast steel, magnesium type, etc., and the mold is a sand type. However, the material of the coil body is not limited to copper, but other conductive materials such as steel may be used.
Further, the coil body is not limited to the pipe shape, and may be a solid shape having no pipe hole, and the roughening treatment applied to the coil body for improving the adhesion of the gold plating layer may be an etching treatment. It can be appropriately selected as necessary within the range not deviating from.

(Supplementary Note) The following technical idea can be understood from the above-described embodiments. The induction coil according to claim 2, wherein the coil body of the induction coil has a pipe hole, and a gold plating layer is laminated on the inner peripheral surface of the pipe hole. This also improves the prevention of high temperature oxidation on the inner peripheral surface of the pipe hole. Therefore, the wear of the inner peripheral surface of the pipe hole is reduced and avoided. Therefore, when a gas such as compressed air is flowed through the pipe hole to cool the induction coil, it is advantageous to reduce the flow resistance of the gas. Furthermore, since the gold forming the gold plating layer is a good conductor of heat, it can also contribute to ensuring the cooling performance from the inner surface of the induction coil by the gas flowing through the pipe hole. The induction coil as described above, wherein a ceramic layer is not laminated on the gold plating layer laminated on the inner peripheral surface of the pipe hole.

This is advantageous for reducing the flow resistance of the gas flowing through the pipe hole and for ensuring the flow passage cross-sectional area of the pipe hole.

[0033]

According to the casting apparatus of the present invention, overheating of the induction coil due to heat radiation and heat conduction from the molten metal can be suppressed by the heat insulating member. Further, since the cooling gas from the gas supply means is sent to the induction coil arrangement chamber and contacts the induction coil, overheating of the induction coil is suppressed. Therefore, high-temperature oxidation of the induction coil can be reduced or avoided, which is advantageous for improving the durability and extending the life of the induction coil.

According to the induction coil of the present invention, the gold plating layer laminated on the coil body can suppress the direct contact between the coil body and the high temperature air, and can reduce or avoid the high temperature oxidation of the induction coil. Further, the gold that constitutes the gold plating layer is a good conductor of heat and has excellent thermal conductivity, which is advantageous for avoiding local heat unevenness of the coil body and for suppressing local overheating of the coil body. Is. Therefore, it is more advantageous to suppress high temperature oxidation in the coil body.

Further, since gold forming the gold plating layer is also a good electric conductor, it is advantageous for ensuring the conductivity of the induction coil and the induction heating property of the induction coil.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view schematically showing a main part of a casting device.

FIG. 2 is a diagram showing a planar form of an induction coil.

FIG. 3 is a sectional view of a main part of an induction coil.

FIG. 4 is a configuration diagram showing a mounting structure of an induction coil.

FIG. 5 is an enlarged sectional view schematically showing a main part of a casting apparatus according to another example.

FIG. 6 is an enlarged sectional view schematically showing a casting device according to a conventional technique.

[Explanation of symbols]

In the figure, 1 is a mold (mold), 102 is a molten metal container, 20 is an induction coil arrangement chamber, 21 and 22 are through holes (gas supply means), 28 is a stalk (hot water supply pipe), 3 is an induction coil, 3
Reference numeral 0 is a coil body, 33 is a gold plating layer, 35 is a ceramic layer, and 5 is a heat insulating sleeve (heat insulating member).

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location H05B 6/42 (72) Inventor Toyoharu Mukai 254 Hongo-cho, Hamamatsu City, Shizuoka Prefecture IC Electric Denki Co. ) Inventor Tsujihiko Yasuda 230 Okita-machi, Nakamura-ku, Nagoya-shi, Aichi Chubu Sukegawa Kogyo Co., Ltd.

Claims (2)

[Claims] 1. A mold provided with a cavity for forming a product, a molten metal container for holding molten metal, and a hot water supply passage for supplying the molten metal held in the molten metal container to the cavity of the mold. In a casting apparatus comprising a hot water supply pipe and an induction coil arrangement chamber surrounding the hot water supply pipe, an induction coil held in the induction coil arrangement chamber and wound around the hot water supply pipe, the induction coil and the hot water supply pipe And a gas supply means for supplying a cooling gas to the induction coil placement chamber to bring the cooling gas into contact with the induction coil in the induction coil placement chamber. A casting machine equipped with an induction coil. 2. An induction coil comprising a coil body made of a conductive material, a gold plating layer laminated on the outer surface of the coil body, and a ceramic layer laminated on the outer surface of the gold plating layer.