JPS61159132A - Inspection of quantity of inclusion in molten metal - Google Patents

Abstract

PURPOSE:To evaluate the quantity of inclusion in a molten metal by operating a selector valve to suck the molten metal into a suction cylinder floated on the surface of the molten metal by a float and determining the depth and time of sinking of the device in this stage. CONSTITUTION:The suction cylinder 4 in which the molten metal 8 is sucked and contained is provided to the refractory float 6 floated on the surface of the molten metal 8 to be inspected and a molten metal introducing pipe 10 attached with a filter 12 is provided to the top end which extends downward from the lower part of said cylinder and is inserted into the molten metal 8. A vacuum buffer tank 2 which can maintain the prescribed degree of vacuum is provided to the upper part of the cylinder 4 and is communicated with the cylinder 4 via the selector valve 24. The molten metal suction device made into such constitution is floated on the surface of the molten metal 8 to be inspected. The valve 24 is operated to communicate the tank 2 with the cylinder 4. The molten metal 8 is sucked into the cylinder 4 through an introducing pipe 10 by the vacuum suction effect of the tank 2. The depth at which the molten metal suction device sinks into the molten metal 8 and the time when said device sinks therein are determined. The quantity of the inclusion in the molten metal 8 is evaluated from the measured values.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for inspecting the amount of inclusions in molten metal, particularly molten aluminum, and particularly to a method that can quickly and easily inspect the amount of inclusions. be.

(Prior art) In general, molten metal (molten metal) before casting, which is obtained by melting metal raw materials such as ingots and scrap, contains various inclusions. It is necessary to remove inclusions from such molten metal so as not to degrade the quality of products manufactured by processing such as , forging, extrusion, etc. Examples of such inclusions include oxides of aluminum and magnesium, suspended non-metallic particles such as refractory particles, etc. in molten aluminum, and these inclusions should be removed as much as possible. This is considered the most important control item in the casting molten metal processing process.

However, such inclusions in molten metal usually have a size of several μm.
Since many of the inclusions are in the range of ~ several tens of microns, and the amount thereof is small, there are inherent problems in collecting such inclusions and quantitatively understanding their abundance.

Conventionally, testing methods for determining the amount of inclusions in molten metal include, for example, sucking or pressurizing the molten metal using a standard filter, concentrating the inclusions on the filter, and observing the cross section of the filter. Or check the degree of clogging of the filter.
There is a method of detecting the suction pressure loss as a change in the weight of the suction molten metal, and in Japanese Patent Publication No. 59-288325, according to the method of detecting the weight of the suction molten metal, a predetermined vacuum pump is connected to the suction cylinder, and an appropriate A method of detecting the weight of the molten metal in the suction cylinder by suctioning and holding the molten metal into the suction cylinder through a suction pipe provided with a filter member has been studied.

(Problem) However, although the method disclosed in Japanese Patent Publication No. 59-28832 has the advantage of being able to relatively quantitatively determine the amount of inclusions, it requires a fairly large device;
There are some drawbacks in terms of operability and quick evaluation of the amount of inclusions.In addition, there are problems with the handling of the vacuum pump gauge and weight detection device, which are limited in their handling. Since it is used in a direct connection, there is a problem in that the degree of vacuum within the suction cylinder tends to vary with each measurement.

(Solution Means) Here, the present invention was made to solve this problem, and its feature is that a refractory float floating on the surface of the molten metal to be inspected is A suction cylinder for sucking and storing molten metal is provided, and a molten metal introduction pipe extending downward from the lower part of the suction cylinder and inserted into the molten metal is provided, and a predetermined filter is attached to the tip of the molten metal introduction pipe. A molten metal suction device is manufactured by using a molten metal suction device in which a vacuum buffer tank that can maintain a predetermined degree of vacuum is provided on the top of a suction tube, and the buffer tank and the suction tube are communicated via a switching valve. is floated on the surface of the molten metal to be inspected, and the buffer tank and the suction cylinder are brought into communication by the switching operation of the switching valve. The molten metal is sucked into the molten metal, the amount of sinking of the molten metal suction device into the molten metal and the sinking time are determined, and the amount of inclusions in the molten metal is evaluated from the obtained sinking amount and sinking time. That's what I did.

(Effects of the Invention) According to the method of the present invention, a predetermined suction tube is floated on the surface of the molten metal using a fire-resistant float, and the molten metal is sucked into the suction tube by operating the switching valve. Since the amount of sinking of the device and its sinking time are determined to evaluate the amount of metal inclusions in the molten metal, the molten metal suction device according to the present invention can be installed anywhere as long as there is space to float it. It has the advantage of being able to be used, and also being able to completely evaluate the amount of inclusions on the spot, and being able to be used separately from the vacuum pump system, and using a small and compact device. becomes possible.

Since the suction pressure is obtained using a vacuum buffer tank, the initial pressure setting is highly reproducible, a constant suction force is always obtained, and there is little variation in the degree of vacuum inside the container. It is possible to demonstrate this.

(Specific Description of Configuration) Hereinafter, in order to clarify the present invention more specifically, the configuration of the present invention will be described in detail with reference to the drawings.

First, FIG. 1 shows a molten metal suction device suitably used in the present invention, in which the molten metal suction device consists of two chambers: an upper vacuum buffer tank 2 and a lower suction cylinder 4. The suction cylinder 4 is housed in a fireproof and heat-insulating float 6 made of lightweight asbestos or the like, so that it can be floated on the surface of a predetermined molten metal 8 to be inspected, such as A1 or its alloy molten metal. . and,
A molten metal introduction pipe 10 is provided that extends downward from the bottom of the suction tube 4 through the flow) 6 and is inserted into the molten metal 8. At the tip of this molten metal introduction pipe IO, porous graphite or A filter holder 14 having a filter 12 made of ceramics or the like is attached. Note that containers made of metal materials such as graphite or stainless steel may be used as the containers constituting the vacuum buffer tank 2 and the suction tube 4, but if the suction tube 4 is made of metal, an appropriate container may be used. It is desirable to line the inner surface with a refractory heat insulating material 16.

On the other hand, the upper vacuum buffer tank 2 is connected to the connecting pipe 18.
The vacuum buffer tank 2 can be detachably connected to a vacuum system such as a vacuum pump through the vacuum buffer tank 2, and the interior of the vacuum buffer tank 2 can be maintained at a predetermined degree of vacuum by opening and closing the valve 20. Note that the degree of vacuum within the buffer tank 2 is detected by a vacuum pressure gauge 22. Further, a switching valve 24 is provided at the bottom of the vacuum buffer tank 2, and its valve body is operated by a rod 28 that is raised and lowered by a rod lifting device (solenoid, etc.) 2 and the inside of the lower suction cylinder 4 can be communicated or disconnected. A heat insulating layer 30 made of a breathable fireproof heat insulating material is formed on the lower surface of the vacuum puffer tank 2, and a metal layer 30 is formed on the bottom surface of the vacuum puffer tank 2 so as to be located at least in a portion of this heat insulating layer that covers the opening of the switching valve 24. A mesh 32 is positioned. This metal mesh 32 is for preventing the molten metal 8 drawn into the suction cylinder 4 from entering the vacuum buffer tank 2 through the switching valve 24 due to the vacuum suction action of the vacuum buffer tank 2.

When inspecting the amount of inclusions in the molten metal 8 using a vacuum suction device with such a configuration, first close the switching valve 24 by operating the rod lifting device 26 to cut off communication with the suction cylinder 4, and then Open the valve 18 and lower the pressure inside the vacuum buffer tank 2 to a predetermined pressure P1 through the connecting pipe 18 using a suitable vacuum pump. The pressure at this time is read by the pressure gauge 22. When the predetermined pressure P is reached, the valve 20 is closed. While maintaining the predetermined degree of vacuum, the molten metal suction device can be moved freely and set at a location where the amount of inclusions is to be measured.

Then, at the intended measurement location, the molten metal introduction pipe 10 of the molten metal suction device is inserted into the molten metal 8, and the filter holder 14 at the tip thereof is immersed in the molten metal 8 to be sufficiently preheated. At this time, the pressure P2 in the suction cylinder 4 increases due to thermal expansion of the internal air, but the expansion is exhausted through the filter 12, and the pressure becomes approximately equal to atmospheric pressure: Po.

Then, in this state, when the rod lifting device 26 is operated and the switching valve 24 is opened to connect the vacuum puffer tank 2 and the suction cylinder 4, the pressure crab P in these containers becomes as shown in the following equation. be.

V++Vt α+1 However, α”V+ /Vz; Tank volume ratio β=Pl/P
t; Pressure ratio Note that the suction pressure: P has different values depending on the type of filter 12. Further, α is related to the size of the device, but is generally preferably 1 to 3, while β is related to the air permeability of the filter 12 used. Furthermore,
When P is less than I Torr, β-1/760<<
1, it can also be approximated as PP,/(α+1).

By the way, when the suction operation of the molten metal 8 is started by communicating the two upper and lower chambers by operating the switching valve 24,
The molten metal 8 enters the suction cylinder 4 through the filter 12, and inclusions in the molten metal 8 are captured by the filter 12.

As the amount of molten metal in the suction cylinder 4 increases, the entire molten metal suction device gradually sinks into the molten metal 8. That is, by sucking up the molten metal 8 from the state shown in FIG. 2(a) into the suction cylinder 4, the state shown in FIG. 2(b) is achieved.
As shown in , it will sink by a height of 1.

At this time, when the amount of inclusions in the molten metal 8 is small, the amount of inclusions captured by the filter 12 is small, so the molten metal 8N passing through the filter 12 is not suppressed, and the suction tube 4
Since the amount of molten metal sucked up into the molten metal 8 increases, the device settles in a short time. However, if there is a large amount of inclusions in the molten metal 8, the amount of inclusions is captured by the filter 12, and the filter 12 In order to reduce the amount of molten metal sucked into the suction cylinder 4 through the suction tube 12, the sedimentation speed is slow, and in severe cases, the sedimentation may stop due to clogging.

Therefore, the amount of inclusions in the molten metal 8 is determined by the sinking behavior of the molten metal suction device described above, in other words, the time it takes for this device to sink to a certain distance: Ito, or the certain time t0 of this device. It can be evaluated based on the sinking amount = 1. Incidentally, in Figure 3(a),
A certain distance 2l.

An example is shown in which the amount of inclusions in the molten metal 8 is evaluated by determining the sinking time t until but,
It is shown. In those examples, curve A to curve C
As the temperature increases, the amount of inclusions in the molten metal 8 increases.

Incidentally, the amount of sinking (l) of such a molten metal suction device can be determined by appropriate known means, such as adding a scale to the float 6,
This can be easily measured by measuring the amount of depression of the device from the reference plane. Also, the molten metal 8 sucked up into the suction tube 4
will be discharged by opening the valve 20 and removing the filter holder 14. In particular, in the case of the molten metal suction device having the above structure, since the suction tube 4 is surrounded by the float 6 made of fireproof heat insulating material, the suction tube is kept in a molten metal state for a considerable period of time. This also prevents problems due to solidification of the suction tube. In the case of the above-mentioned apparatus, it is also possible to remove the apparatus main body from the float 6 and evaluate the amount of inclusions as a change in the weight of the suction cylinder, as in the conventional method.

Thus, according to the invention, the molten metal suction device used is separate from the vacuum pump system and is therefore easy to handle, small and compact, and such a vacuum suction device can be floated. If there is space, it can be used anywhere, and the amount of inclusions can be completely evaluated on the spot. This method has excellent advantages such as good reproducibility of pressure settings, constant suction force, and less variation in the degree of vacuum inside the container unlike conventional methods.

It should be noted that the present invention is not to be construed as being limited to the above-mentioned specific examples, and may be implemented in various modified forms without departing from the spirit thereof. It goes without saying that such embodiments are also included in the scope.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an example of a molten metal suction device suitably used in the present invention, and FIGS. 2(a) and (b) are
FIG.
) and (b) are the subduction time and subduction amount (
It is a graph showing the relationship between (distance). 2: Vacuum buffer tank 4: Suction cylinder 6: Float 8: Molten metal 10: Molten metal introduction pipe 12: Filter 14: Filter holder 24: Switching valve
26: Rod lifting device 28: Rod 3
0: Heat insulation layer 32: Metal mesh Applicant: Sumitomo Light Metal Industries, Ltd. Figure 2 (a) (b) Figure 3 (a) (b) Time

Claims (1)

[Claims] A refractory float floating on the surface of the molten metal to be inspected is provided with a suction tube into which the molten metal is sucked and contained, and the suction tube extends downward from the bottom of the suction tube and is inserted into the molten metal. A molten metal introduction pipe with a predetermined filter attached to the tip is provided, and a vacuum buffer tank that can maintain a predetermined degree of vacuum is provided above the suction tube, and a switching valve is connected between the buffer tank and the suction tube. Floating the molten metal suction device on the surface of the molten metal to be inspected using a molten metal suction device communicated through the molten metal suction device, and communicating the buffer tank and the suction cylinder by switching operation of the switching valve, sucking the molten metal into the suction cylinder through the molten metal introduction pipe by the vacuum suction action of the buffer tank, and determining the sinking amount and sinking time of the melt suction device into the molten metal;
A method for inspecting the amount of inclusions in molten metal, which comprises evaluating the amount of inclusions in the molten metal from the obtained sinking amount and sinking time.