JPH0225268A - Detection of run-out - Google Patents

Abstract

PURPOSE:To surely detect the run-out in a suction casting method, etc., by continuously detecting the molten metal surface height in a furnace at the time of pouring and detecting the run-out in accordance with the detection of the abnormality in the fall of the molten metal surface. CONSTITUTION:The means for detecting the molten metal 4 surface height such as IR distance meter 14 is provided to the upper part of the side wall of the melting furnace 2 and is connected to a vacuum pump 11. The molten metal 4 in the furnace 2 is sucked and poured into a cavity 9 through a stoke 13 when the pressure in the chamber is reduced by the vacuum pump 11. The fall of the molten metal surface ceases when the molten metal is filled in the cavity 9. Detection and decision are made that the pouring amt. exceeds the volume of the cavity 9 from the fall of the continuously detected fall of the molten metal surface height when the run-out arises at this time. The distance meter 14 stops the vacuum pump 11 immediately in this way. The run-out amt. is, therefore, minimized and the damage of the casting device by the run-out molten metal is prevented.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is applicable to a method such as a suction method, a low pressure method, or a reduced pressure method, in which power is supplied by the pressure difference between the inside of a furnace such as a melting furnace or a holding furnace and the inside of a chamber. The present invention relates to a method for detecting the occurrence of leakage when performing the warming method.

In conventional techniques such as the vacuum casting method or the low-pressure casting method, the molten metal in the furnace is injected into the cavity by the pressure difference created by reducing the pressure in the cavity or increasing the pressure in the furnace. Even after the injected molten metal fills the cavity, it is common to maintain the pressure difference for a certain period of time to create a feeder effect and prevent the occurrence of sinking, etc., but leakage may occur. As a result, the leaked molten metal will be constantly replenished from inside the furnace, so if the leak is not detected and the filling process is not stopped immediately, the leaked molten metal will become suspended and damage the Shijo equipment. There was a risk. In particular, in suction molding, it was difficult to detect leakage from the mold because mold 1 was housed in the mold chamber.

The conventional 39 in 8 of this suction poetic method or decompression N method
As a leakage detection method, for example, Japanese Patent Application Laid-Open No. 61-2860
There is a method described in Publication No. 53. This detects the exhaust temperature during depressurization in the Suction Poetry Method or the Decompression Poetry Method, and determines whether the temperature of the exhaust gas or the temperature above the exhaust temperature exceeds the temperature in the mold. A humidity level that cannot be exceeded when the hot water is not being poured is preset, and it is determined whether or not the exhaust temperature during pouring exceeds the set temperature, thereby detecting whether or not hot water is leaking.

Another method for detecting temperature in the suction casting method or the reduced pressure y method is to arrange two or more detection conductors in the chamber or mold, and when a leak occurs, a short circuit occurs between these detection conductors. Therefore, there is a method of detecting the short circuit and detecting the leakage.

Three problems that the invention attempts to solve However, of the two well-described leakage detection methods, the former
This method detects leakage based on abnormally high exhaust temperature or abnormally fast rise in exhaust temperature, but if the same mold is repeatedly soaked, the mold temperature will gradually rise. Therefore, the humidity of the exhaust air increases, and when a high mold temperature is required, the mold must be preheated to a high temperature before casting, making it difficult to detect abnormalities in the exhaust temperature.
Also, if a certain amount of molten metal does not leak out before the exhaust temperature rises, an abnormality can be detected. 9) There was a problem that the amount of deformation increased.

In the latter case, in order to be able to accurately detect a 1g leak no matter where in the mold a leak occurs, it is necessary to provide a large number of detection conductors corresponding to various locations in the mold. However, the +14 construction of the mold and Buyamba,
There are limits to the locations where the detection conductor can be installed and the number of electric wires that can be installed, and there is a problem in that leaks occurring in locations where the detection conductor is not installed cannot be detected.

This invention was made against the above-mentioned technical background.
The purpose of this invention is to provide a detection method that can quickly and reliably detect leakage in suction casting, low-pressure packing, vacuum casting, or the like.

Means for Solving the Problems As a means for solving the above problems, the method of the present invention involves pouring molten metal in a furnace such as a melting furnace or a holding furnace using a pressure difference between the inside of the furnace and the inside of a mold cavity. In the method of detecting leakage in the casting method, the height of the molten metal level in the furnace, which changes with time, is continuously detected, and it is detected from the amount of drop in the molten metal level that the amount of poured molten metal exceeds the volume of the cavity. The feature is that if this happens, it is determined that there is a hot water leak.

Operation According to the above method, the volume of the cavity and the volume of the stalk are determined in advance, and the relationship between the amount of poured metal and the drop in the level of the melt in the furnace is determined, and the wet surface in the furnace is When it detects that the amount of poured metal exceeds the volume of the cavity based on the amount of descent of the I-irradiation surface, it is determined that a leak has occurred, and the pouring is stopped and the inside of the cavity and The molten solid in the stalk is returned to the furnace.

Embodiment Hereinafter, an embodiment in which the water leakage detection method of the present invention is applied to a case where Y-type suction is induced in an intake manifold made of aluminum alloy will be described with reference to FIGS. 1 to 4.

FIG. 1 shows a suction casting apparatus used in the method of this embodiment, and the casting apparatus 1 is equipped with a melting furnace 2 and a forming part 3, and the melting furnace 2 has an inner surface formed vertically. 5, an aluminum alloy 4 is stored inside it.

On the other hand, the M-building part 3 includes a surface plate 5 installed horizontally above the melting furnace 2, a sand mold 6 placed on the surface plate 5 with the mouth 6a facing downward, and the sand mold 6. It has a chamber 7 that airtightly covers the periphery of the sand mold 6, and a core 9 is formed in the sand mold 6 between it and the core 8. Also on the side of chamber 7! A pressure reduction hole 10 is formed in the upper part, and a pipe 12 from a vacuum pump 11 is connected to this pressure reduction hole 10. Further, the opening 6a communicating with the cavity 9 of the sand mold 6 is provided vertically by immersing the dismount side into the melting hole 4 in the melting furnace 2, and is provided so as to pass through the fixed path 5 in the vertical direction. A steel stalk 13 is connected and laid down. Furthermore, an infrared distance meter 14 is provided at the upper part of the side gate of the melting furnace 2 so as to face perpendicularly to the surface of the molten metal 4. gland 15
is wired, and when the infrared distance meter 14 detects a drop in the hot water level by a predetermined amount or more, it sends a signal via this lead guard 15, and at the same time as stopping the vacuum pump 11, the depressurized chamber 7 is immediately moved. It is designed to be opened to the atmosphere.

Next, a case will be described in which sand mold suction casting is actually performed using the IJ a device 1 configured as described above.

The volume of the cavity 9 of the sand mold 6 is 2220 cI.
I, the volume inside the stalk 13 from the melt level in the melting furnace 2 to the cavity 9 was 4020 d, and the area of the measured surface of the melting furnace 2 was 2830 ut. Also, the amount of drop in the hot water level per shot calculated from these values is 2.
．． 2 crn, and if we graph the change in the height of the water during pouring, with the height of the hot water level on the x-axis and the pouring time on the y-axis, we get something like Figure 2.

That is, when the vacuum pump 11 is operated to reduce the pressure in the chamber 7, the sand mold 6 housed in the chamber 7 is
Since the pressure inside the cavity 9 is reduced, the molten metal 4 in the melting furnace 2 is sucked through the stalk 13 and injected into the cavity 9, and as the pouring time elapses, the surface measurement gradually decreases and the area I is reached. ), when the molten metal fills the furnace 9 at time A, the level of the molten metal stops decreasing. The surface measurement descent ff1H at this point i is calculated as -2.2cxr. Next, with the cavity 9 filled with molten metal, the pressure inside the chamber 7 is continued to be reduced for a certain period of time (section 2) to provide a feeder effect and to check for leakage.

At this time, if there is no leakage, the hot water level will not fall and will remain at a constant level, and if wet leakage occurs, the hot water level will drop roughly, making it difficult to detect bulk leakage. can.

After a certain period of time has elapsed, at time B, the vacuum pump 11 is stopped, the reduced pressure is released, and the inside of the chamber 7 is opened to atmospheric pressure.
The molten metal in the part directly above the molten metal (I) and the molten metal in the stalk 13 descends and returns to the melting furnace 2, so that the level of the molten metal in the melting furnace 2 rises (section I[[)]. Also, during the next casting, changes in the molten metal level are detected using this molten metal level as a new reference.

Here, when we investigated the difference in W4 from the calculated value obtained by actually suctioning and pouring molten metal into the sand mold 6 that does not leak, we found that the amount of descent of the molten metal level in the melting furnace 2 is At time A, when it was filled with water, it descended to 2.5 cm. This is melting furnace 2
It is thought that some of the molten metal adhered to and remained on the inner surface of the side wall, so the amount of descent was greater than in Keitan m.

Therefore, if the allowable amount of leakage from the sand mold 6 is 5007, then the lower I4M of the open surface for 500 cit is approximately 0.
27J, the amount of drop in the hot water level H for detecting a leak from the amount of drop in the hot water level is set to 2.7 ctn, and a sand mold 6 with a hole 16 of diameter 311#I drilled in the cavity 9 is used. By actively generating heat and moisture, the casting apparatus 1 performs casting at a depressurizing speed = 100 mmHU/
When testing the ability to detect leakage, the height of the hot water level changed as shown in the graph shown in Figure 4. As a result, the pouring progresses and the amount of water level drop decreases to H value (2,7
When the infrared range finder 14 detects that the distance ca) has been exceeded,
The construction equipment 1 detects the occurrence of leakage and turns on the vacuum pump 11.
At the same time, the inside of the chamber 7 was opened to the atmosphere, and the gushing was immediately stopped. In addition, the leakage Φ that occurred until the casting device 1 detected the lagoon leakage and stopped pouring at this time was 630.
It was ci. The reason why this amount of molten metal leaked exceeded the set ej leakage tolerance value of 500 ul was because the molten metal had a capacity of 9.
This is because many leaks occurred before the tank was completely filled. Further, although more molten metal leaked than the allowable value, there was no damage to the chamber 7, constant M5, etc. of the casting apparatus 1, and recovery for the next casting was easy.

Next, for comparison with this example, when casting was carried out under the same conditions as in conventional suction casting with supplementary prevention of leakage, no leakage was detected. , 15,000 cal of molten metal leaked into Chanhuff,
As a result, the chamber 7, the edict 5, and the stalk 13 of the casting apparatus 1 could no longer be reused.

In addition, in the above embodiment, an example was explained in which the leakage detection method was applied to sand mold suction casting.
It can be carried out in almost the same way when performing other low-pressure casting or reduced-pressure molding.

As described in detail, the seepage/leakage detection method of the present invention detects the layer temperature in a furnace such as a melting furnace or a holding furnace using a pressure difference between the inside of the furnace and the inside of a mold cavity. In the wetness detection method, the height of the molten metal level in the furnace that changes as the molten metal is poured is continuously detected, and if it is detected from the amount of drop in the molten metal level that the IM exceeds the volume of the cavity, leakage is detected. This makes it possible to accurately detect the occurrence of 1i11 leakage and stop pouring, thereby minimizing molten metal leakage and preventing damage to the casting equipment due to leaked molten metal. be able to.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the method of the present invention. Figure 1 is an explanatory diagram showing a casting device used to carry out the method of the present invention, and Figure 2 is an illustration of the casting surface at high tide. Figure 3 is a cross-sectional view of a sand mold with holes drilled to generate mm deviation, Figure 4 is the surface of the leakage when leakage occurs during actual casting. It is a graph showing changes. DESCRIPTION OF SYMBOLS 1... Support equipment, 2... Melting furnace, 5... Surface plate, 6... Sand mold, 7... Chamber, 9... Cavity, 11... Vacuum pump, 13...・Stoke, 14-0° infrared rangefinder. Applicant Toyota Motor Corporation v. J. Shin Co., Ltd. Agent Patent Attorney Yutaka 1) Substitution (1 other person) Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a method for detecting leakage in a casting method in which molten metal is poured into a furnace such as a melting furnace or a holding furnace by using the pressure difference between the inside of the furnace and the inside of a mold cavity, the molten metal level in the furnace changes as the metal is poured. A hot water leak detection method characterized by continuously detecting the height and determining a hot water leak when it is detected from the amount of drop in the hot water level that the amount of poured metal exceeds the volume of a cavity.