JPH0655254A - Mechanism for detecting leakage of molten metal in suction casting device - Google Patents

Abstract

PURPOSE:To prevent malfunction of a detector for leakage of molten metal. CONSTITUTION:The detector 40 for leakage of molten metal in a suction casting device is provided with one pair of insulation coating electrodes 30, 32 arranged along the lower end of an inner side surface of a chamber 14 so as to surround a mold 12. Then the insulation coating electrodes 30, 32 are connected to the detector body 40k to measure electric resistance between both electrodes 30, 32. At the time of generating the leakage of the molten metal, the molten metal flowing out from the mold is brought into contact with the insulation coating electrodes 30, 32 and vinyl films 30h, 32h of the insulation coating electrodes 30, 32 are melted with heat of this molten metal, and each electrode is mutually brought into contact with the other electrode and the electric resistance is made to be low. Further, in the case of generating no leakage of the molten metal, the vinyl films 30h, 32h of the insulation coating electrodes 30, 32 are not melted and both electrodes 30, 32 are held in the condition of insulation from the outsides as they are. Therefore, it is prevented that the leakage of the molten metal is decided by some disturbance even in the case of generating no leakage of the molten metal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction method in which a mold is covered with a chamber and the space in the chamber is depressurized to indirectly depressurize the cavity in the mold to suck molten metal into the cavity. The present invention relates to a molten metal leak detection mechanism for a casting device.

[0002]

2. Description of the Related Art In a suction casting method, a cavity in a mold is depressurized to generate a pressure difference between the cavity and a melting furnace for storing the molten metal, so that the molten metal in the melting furnace is formed into a cylindrical shape. Aspirate into the cavity through the stalk.
And, even after the molten metal is filled in the cavity, by maintaining the pressure difference between the cavity and the melting furnace for a certain time,
It has a feeder effect to prevent shrinkage cavities.
However, when the molten metal leaks due to cracking of the mold, improper alignment, etc., the molten metal is continuously sucked due to the pressure difference between the cavity and the melting furnace, and a large amount of molten metal leaks out. In particular, in the suction casting method, the chamber is covered with the mold, and the space in the chamber is decompressed to indirectly decompress the cavity in the mold. Therefore, the appearance of the mold cannot be visually confirmed from the outside, and it has been difficult to detect molten metal leak.

In order to solve the above-mentioned problem, a technique for detecting molten metal leakage in the suction casting method is disclosed in Japanese Utility Model Laid-Open No. 2-32358.
It is described in Japanese Patent Publication No. This method for detecting molten metal leakage sets a stalk (made of a conductive material) for guiding the molten metal to the sprue of the mold in a state of being electrically insulated from the mold surface plate, and further setting a chamber in the mold. The electric resistance between the stalk and the chamber is monitored in the covered state. That is, since the stalk is set in an electrically insulated state with respect to the mold surface plate, the stalk and the chamber are also kept in an electrically insulated state. Therefore, even during casting, the electric resistance between the chamber and the stalk has a large value when the molten metal is not leaking. On the other hand, when the molten metal leaks from the mold, the molten metal accumulates on the mold surface plate, and the chamber and the stalk are connected by the molten metal. Therefore, the electric resistance between the chamber and the stalk becomes small. Therefore, if the electric resistance between the chamber and the stalk is equal to or less than a predetermined value, it can be determined that the molten metal is leaking. In addition, actually, when a constant voltage is applied between the chamber and the stalk, the electric resistance is converted into a current value and detected.

[0004]

However, in the conventional method for detecting molten metal leakage, the problem of the material of the insulating material mounted between the stalk and the mold surface plate causes a reliable insulation between the stalk and the chamber. Sometimes you can't. Therefore, an electric current may flow between the chamber and the stalk even when the molten metal has not leaked. Further, since the electric circuit for detecting the leakage of molten metal is not insulated from the outside, a current leaked from the melting furnace may flow between the chamber and the stalk. Therefore, it may be erroneously determined as a molten metal leak even though the molten metal has not leaked. A technical object of the present invention is to cover a pair of electrodes for detecting leakage of water with an insulating coating, and the insulating coating is melted only when the molten metal comes into contact with the electrodes,
By electrically connecting both electrodes, the molten metal leak detector does not operate except the molten metal leak, and the reliability of the molten metal leak detection device is improved.

[0005]

The above-mentioned problems can be solved by a molten metal leak detection mechanism of a suction casting apparatus having the following structures. That is, the molten metal leak detection mechanism of the suction casting device according to the present invention covers the mold with a chamber, and decompresses the space in the chamber to indirectly decompress the cavity in the mold, and to melt the molten metal into the cavity. In a molten metal leak detection mechanism of a suction casting apparatus that sucks in, a plurality of insulating coating electrodes arranged along the lower end of the inner side surface of the chamber so as to surround the mold, and each of the insulating coating electrodes And a connection state detecting means for detecting that the electrode portions are electrically connected to each other.

[0006]

According to the present invention, a plurality of insulating coating electrodes are arranged along the lower end of the inner surface of the chamber so as to surround the mold. Therefore, if a molten metal leak occurs during casting, the molten metal leaked from the mold comes into contact with the insulating coated electrode.
The heat of the molten metal melts the insulating coating of the insulating coated electrodes, and the respective electrode portions are connected to each other by the molten metal. Then, the connection state detecting means detects the state in which the respective electrode portions are electrically connected to each other. Further, since the insulating coating electrode is wired so as to surround the mold, it is possible to reliably detect at which position of the mold the leakage of the molten metal occurs. On the contrary, if the molten metal does not leak, the insulating coating of the insulating coated electrode is not melted and is kept as it is. Therefore, each electrode portion is maintained in a state of being insulated from the outside. Therefore, for example, a leakage current from a melting furnace or the like does not flow into the electrode portion, and a molten metal leak is not erroneously determined even though the molten metal leak does not occur. Therefore, the reliability of the molten metal leak detection mechanism is improved.

[0007]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A molten metal leak detector of a suction casting apparatus according to an embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a vertical sectional view of a suction casting apparatus 10 equipped with a molten metal leak detector 40 according to the present embodiment, FIG. 2 is a sectional view of an essential part of FIG. 1, and FIG. 3 is a state in which molten metal leakage occurs. 1 is a partial cross-sectional view of the suction casting device 10. Suction casting device 10
As shown in FIG. 1, is equipped with a mold 12 and a surface plate 16 for mounting an airtight chamber 14 covering the mold 12. The surface plate 16 is a flat plate made of iron and formed into a rectangular shape in plan view, and also serves as a bottom plate of the airtight chamber 14, and a through hole 16k is formed at a predetermined position. Then, the cylindrical stalk 20 is inserted into the through hole 16k. Here, a flange portion 20f is formed at the upper end of the stalk 20, and the stalk 20 is positioned by being supported by the surface plate 16 from below. Further, the space between the through hole 16k and the stalk 20 is sealed by a sealing material 19.

The mold 12 is composed of an upper mold 12a and a lower mold 12b. By combining the molds 12a and 12b, a cavity 12k is formed inside the mold 12.
Is formed. Further, the lower mold 12b is formed with a sprue 12y in a central longitudinal direction, and the mold 12 is positioned on the surface plate 16 so that the sprue 12y is connected to the flange portion 20f of the stalk 20. It The mold 12 positioned on the surface plate 16 is covered with an airtight chamber 14. The airtight chamber 14 is manufactured in a box shape, and a decompression port 14p connected to a vacuum pump (not shown) is formed on the upper surface thereof.
Further, at the lower end of the side wall of the airtight chamber 14, the sealing material 1
5 is attached, and the inside of the airtight chamber 14 is kept airtight with the airtight chamber 14 placed on the surface plate 16.

Outside the upper part of the airtight chamber 14,
A detector body 40k of the leak detector 40 is installed. Further, inside the airtight chamber 14, a pair of insulating coating electrodes 30 and 32 are arranged in parallel along the lower end of the side surface so as to surround the mold 12. As shown in FIG. 2, the insulating coated electrodes 30 and 32 are formed by covering the outer circumferences of the iron electrodes 30s and 32s with vinyl coatings 30h and 32h. With this structure, the electrodes 30s and 32s are formed.
, And the electrodes 30s and 32s and the airtight chamber 14 are completely insulated from each other. Then, the insulating coating electrodes 30 and 32 are connected to the detector main body 40k by insulating coating conductive wires 40 and 42. The detector body 40k is
The electric resistance R between the insulation-coated electrodes 30 and 32 is measured, and a constant voltage is applied between the insulation-coated electrodes 30 and 32 in order to convert the electric resistance R into a current value for measurement. ing. That is, each insulation-coated electrode 30, 32
If the spaces are completely insulated (R = ∞), the electrodes 30, 3
2. No electric current flows in the electric circuit constituted by the insulating coated conductors 40 and 42 and the detector main body 40k. On the contrary, when the electrodes 30 and 32 are connected by the molten metal, a current corresponding to the electric resistance of the molten metal flows in the electric circuit. That is, the detector body 40k functions as a connection state detecting means for detecting the electrical connection state between the electrodes 30s and 32s. When the detector main body 40k detects the connection state between the insulating coating electrodes 30 and 32, the detector main body 40k issues an alarm, stops the vacuum pump, and opens the airtight chamber 14 to the atmosphere.

As described above, the stalk 2 is attached to the surface plate 16.
When 0, the mold 12 and the airtight chamber 14 are set, the preparation for casting is completed. Then, when the preparation for casting is completed, the platen 16 descends and the tip of the stalk 20 is dipped into the molten metal stored in the melting furnace 18 by a predetermined dimension. When the tip of the stalk 20 is immersed in the molten metal of the melting furnace 18, the inside of the airtight chamber 14 is depressurized by a vacuum pump. As a result, the inside of the cavity 12k of the mold 12 arranged in the airtight chamber 14 is indirectly decompressed, and the molten metal in the melting furnace 18 is sucked into the cavity 12k through the stalk 20. Then, in order to have a pushing effect even after the cavity 12k is filled with the molten metal, the airtight chamber 1 is kept until the molten metal is solidified.
The pressure reduction in 4 is continuously performed. By giving the effect of the molten metal in this way, it is possible to prevent the occurrence of casting defects such as shrinkage cavities. Mold 1 after the prescribed solidification time
When the molten metal in 2 solidifies, the airtight chamber 14 is opened to the atmosphere, the unsolidified molten metal in the sprue 12y and the stalk 20 is returned to the melting furnace 18, and the casting is completed.

Next, the operation of the molten metal leak detector 40 of the suction casting apparatus according to this embodiment will be described. During casting, cracks or the like occur in the mold 12 due to some cause, and as shown in FIG.
When the molten metal leak occurs, the insulating coating electrodes 30 and 32 of the molten metal leak detector 40 arranged so as to surround the casting mold 12,
The leaked molten metal comes into contact. Molten metal is insulation coated electrodes 30,3
Upon contact with 2, the vinyl coatings 30h and 32h of the insulating coated electrodes 30 and 32 are melted by the heat of the molten metal. Further, the molten metal comes into contact with the iron electrodes 30s and 32s of the insulating coated electrodes 30 and 32, so that both electrodes 30
The s and 32s are mutually connected by a molten metal. That is,
The electrodes 30 and 32 are electrically connected to each other, and the electrodes 30s and 32s and the insulating conductor 4 are electrically connected.
Current flows through an electric circuit formed by the detectors 0 and 42 and the detector main body 40k, and leakage of molten metal is detected. When the leak of the molten metal is detected, the detector main body 40k gives an alarm, stops the vacuum pump, and opens the inside of the airtight chamber 14 to the atmosphere. As a result, casting is stopped and the molten metal in the stalk 20 is returned to the melting furnace 18. Therefore, the molten metal does not continuously leak from the mold 12.

As described above, according to the present embodiment, since the insulating coating electrodes 30 and 32 of the molten metal leak detector 40 are arranged along the lower end of the inner side surface of the airtight chamber 14 so as to surround the mold 12. No matter which direction the molten metal leaks, the molten metal leak can be reliably detected. Further vinyl coating 30h, 32
As long as h is not melted, the insulation of the insulating coated electrodes 30 and 32 is ensured, so that the leakage current from the melting furnace 18 does not flow into the electrodes 30s and 32s. Therefore, the molten metal leak is not erroneously determined even though the molten metal leak does not occur, and the reliability of the molten metal leak detector 40 is improved. Further, since the space between the mold 12 and the airtight chamber 14 is generally set to be small, it is possible to detect the molten metal leak only by leaking a small amount of the molten metal.

[0013]

According to the present invention, when there is no molten metal leakage, each electrode portion is kept in an insulated state, so that leakage current from the outside does not flow into the electrode portion and the molten metal leakage does not occur. There is no misjudgment. Also,
It is possible to reliably detect where the molten metal leaks in the mold. Therefore, the reliability of the hot water leak detection mechanism is improved, and unmanned hot water leak monitoring can be performed. Further, since the detection mechanism is simple, the cost can be reduced and the device can be downsized.

[Brief description of drawings]

FIG. 1 is an overall sectional view of a suction casting apparatus according to an embodiment of the present invention.

FIG. 2 is a detailed view of a main part of FIG.

FIG. 3 is a cross-sectional view of a main part of the suction casting device in a state where melt leakage has occurred.

[Explanation of symbols]

 12 Mold 14 Airtight Chamber 16 Surface Plate 20 Stoke 18 Melting Furnace 30 Insulation Coated Electrode 32 Insulation Coated Electrode 40 Hot Water Leakage Detector 40k Detector Main Body (Conduction State Detection Means)

Front page continued (72) Inventor Masao Nakayama 1 Toyota Town, Toyota City, Aichi Prefecture, Toyota Motor Corporation (72) Inventor Hiromi Munakata 1 Toyota Town, Toyota City, Aichi Prefecture Toyota Motor Corporation (72) Invention Yoshihiko Sugimoto, Toyota Town, Toyota City, Aichi Prefecture

Claims (1)

[Claims] 1. A molten metal leak detection of a suction casting device for covering a mold with a chamber and decompressing a space in the chamber to indirectly decompress the cavity in the mold to suck molten metal into the cavity. In the mechanism, a plurality of insulating coating electrodes arranged along the lower end of the inner side surface of the chamber so as to surround the mold, and respective electrode portions of the insulating coating electrodes are electrically connected to each other. And a connection state detecting means for detecting such a situation.