JP2005134296A - Method and instrument for measuring amount of inclusion in molten aluminum - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an inclusion measuring instrument which measures quickly and easily an inclusion in a molten aluminum with excellent reproducibility, and is usable for process control in a production field. <P>SOLUTION: A friction coefficient is low in an inner face of a crucible 26 and the inner face of the crucible 26 has an excellent mold releasing property, because a mold release layer 40 of high heat resistance is formed at least in the inner face of the crucible 26. The molten aluminum is hardly deposited and left thereby on the inner face of the crucible 26, when pressure-filtrating the molten aluminum in the crucible 26. An end point of the pressure filtration is clear, and dispersion in a measuring operation is hardly generated among measuring persons, even when the plurality of measuring persons operates the inclusion measuring instrument 10, since substantially all the molten aluminum fed into the crucible 26 is pressure-filtrated by a filter 44 to enhance separation of the inclusion from the molten aluminum. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a method for measuring the content of inclusions present in a molten metal such as aluminum or an aluminum alloy, and a measuring apparatus therefor.

Generally, in a molten aluminum or aluminum alloy (hereinafter referred to as “aluminum molten metal”), non-metallic inclusions such as Al ₂ O ₃ , MgAl ₂ O ₄ and MgO and other impurities (hereinafter simply referred to as “inclusions”). ) Are mixed, and these inclusions cause defects such as hard spots during casting.

  In addition, aluminum (hereinafter referred to as “Al”) has about one-third of the energy required for remelting when electrolytically refining Al ore and is a metal suitable for recycling. The proportion of scrap used as a casting raw material is increasing, but it is known that the molten metal obtained by melting this Al scrap has more inclusions than those using new ingots. ing.

  Therefore, in order to improve the quality of cast products and avoid troubles in post-processing steps, it is necessary to quickly and accurately grasp the amount of inclusions in the molten aluminum currently used in each manufacturing process at the foundry. There is.

  For this reason, conventionally, when casting Al or Al alloy castings, inclusions in molten aluminum are measured by a pressure filtration method. With this pressure filtration method, when the molten aluminum is pressure filtered with a filter, the change over time in the weight of the molten aluminum (that is, the filtration curve) is obtained, and the cleanliness of the molten aluminum is measured by comparing this with a reference. In addition, the filtered filter and Al remaining thereon are cut and polished, and the type and amount of inclusions are analyzed metallurgically using an optical microscope. According to this method, it is possible to know not only the amount of inclusions in the molten aluminum but also the type of inclusions.

  However, in this pressure filtration method, various instruments are used for analysis, and the analysis operation is complicated and the analysis takes time. Therefore, it is not suitable for fine process control at the time of Al dissolution at the Al casting site. There was a problem that there was.

  As a technique that can solve such a problem, a glass fiber filter is attached to one end of a pipe body of a predetermined length, and one end of the pipe body to which this filter is attached is inserted into a molten aluminum pipe. A technique for measuring the amount of inclusions in a molten aluminum by applying a vacuum at a predetermined pressure from the other end of the body to suck the molten aluminum into the tube and measuring the length of the sucked molten aluminum is known. (For example, refer to Patent Document 1).

  According to this technique, the amount of inclusions in the molten aluminum can be relatively and easily compared.

  However, in order to know exactly how much inclusions are present in the molten aluminum, there is a problem that a calibration curve must be prepared separately to determine the amount. In other words, this technique cannot uniquely determine the amount of inclusions in the molten aluminum. For this reason, there has been a problem that measurement values are likely to vary among measurers and reproducibility is not so good. Such a problem can be similarly applied to the pressure filtration method described above.

In addition, the equipment used at the manufacturing site needs to be durable enough to withstand the hard work, but with this technology, the measuring device is composed of an elongated tube made of glass or the like. The body breaks and becomes unusable. Therefore, there is a problem in durability when used at the manufacturing site.
JP 2001-174451 A (page 2-4, FIG. 2)

  Therefore, the main problem of the present invention is to provide an inclusion amount measuring device in molten aluminum that can quickly and easily measure the amount of inclusions in molten aluminum with high reproducibility and can be used for process management at the manufacturing site. is there.

  According to the first aspect of the present invention, “a crucible in which a high heat-resistant release layer (40) is formed on at least an inner surface thereof and a filter (44) is attached to an opening (26b) provided on the bottom surface thereof ( 26) Prepare molten aluminum in the crucible (26), pressurize the molten aluminum in the crucible (26), filter the whole amount with a filter (44), and measure the amount of inclusions by the weight difference between the molten aluminum before and after filtration. '' This is a characteristic method for measuring the amount of inclusions in molten aluminum.

  The invention described in claim 2 is an apparatus for carrying out the method for measuring the amount of inclusions in the molten aluminum according to claim 1, wherein “at least the inner surface has a high heat-resistant release layer (40)”. And a crucible (26) provided with an opening (26b) on the bottom surface thereof, and a filter that is attached to the opening (26b) of the crucible (26) and filters the molten aluminum contained in the crucible (26) ( 44), a pressurizing means for pressurizing the molten aluminum contained in the crucible (26), and a measuring instrument (14) for measuring the weight of the molten aluminum before and after filtration. This is an apparatus for measuring the amount of inclusions in a molten metal (10).

  In the inclusion amount measuring method and the inclusion amount measuring apparatus (10) of the present invention, since the high heat-resistant release layer (40) is formed on at least the inner surface of the crucible (26), the inner surface of the crucible (26) Low coefficient and good releasability. Therefore, when the molten aluminum is put into the crucible (26) and the molten aluminum is pressure filtered through the filter (44) attached to the opening (26b) at the bottom of the crucible (26), the crucible (26) There is little molten aluminum adhering to or remaining on the inner surface, and almost all of the molten aluminum charged in the crucible (26) can be filtered. Also, almost all of the molten aluminum charged in the crucible (26) is pressure filtered with a filter (44) so that the molten aluminum and inclusions are completely separated. It is clear that even when a plurality of measurers operate the inclusion amount measuring apparatus (10), the measurement operations of the measurers are unlikely to vary. Therefore, the amount of inclusions in the molten aluminum can be measured accurately and with good reproducibility regardless of the number of measurements and the difference of the measurer.

  Furthermore, almost all of the molten aluminum charged in the crucible (26) can be pressure filtered, and the amount of inclusions can be easily determined by the difference in weight of the molten aluminum before and after filtration, so there is no need to create a calibration curve, etc. The amount of inclusions in the molten aluminum can be measured quickly and easily.

  Since the inclusion amount measuring device (10) does not include a fragile member such as an elongated tube, the device has high durability and can sufficiently withstand use at the manufacturing site.

  The invention described in claim 3 is characterized in that, in the inclusion amount measuring device (10) in the molten aluminum according to claim 2, "the release layer (40) is made of boron nitride". Thus, a strong release layer (40) having high heat resistance equal to or higher than the temperature of the molten aluminum can be formed.

  According to the present invention, since the heat-resistant release layer is formed on at least the inner surface of the crucible, the molten aluminum is less likely to adhere to the inner surface of the crucible and remains almost the same as the molten aluminum charged in the crucible. The whole amount can be filtered. In addition, since almost the entire amount of the molten aluminum charged in the crucible is pressure filtered with a filter, the end point of the pressure filtration is clear and the measurement operation of each measurer is unlikely to vary. Therefore, the amount of inclusions in the molten aluminum can be measured accurately and with good reproducibility regardless of the number of measurements and the difference of the measurer.

  Furthermore, since the amount of inclusions in the molten aluminum can be easily determined from the weight difference between the molten aluminum before and after filtration, it is not necessary to prepare a calibration curve or the like, and it can be measured quickly and easily.

  And since a fragile member is not included in the inclusion amount measuring apparatus, the durability of the apparatus is high and it can sufficiently withstand the use at the manufacturing site.

  Therefore, it is possible to provide an apparatus for measuring the amount of inclusions in molten aluminum that can quickly and easily measure the amount of inclusions in the molten aluminum and that can be used for process management at the manufacturing site.

  The inclusion amount measuring device (10) of one embodiment of the present invention shown in FIG. 1 is a device that measures the amount of inclusions in molten aluminum quickly and easily with good reproducibility. , Measuring instrument (14) and control device (16).

  The measuring device body (12) is for pressure filtration of a molten aluminum prepared by melting an Al metal, or a molten aluminum directly collected from a manufacturing process, and a rectangular frame (18), The pressure filtration device (20) mounted on the upper part of the frame (18) and the aluminum melt pressure-filtered by the pressure filtration device (20) are detachably attached to the lower part of the frame (18). And a molten metal tray (22). A caster (18a) is attached to the bottom surface of the frame (18) so that the measuring device main body (12) can move.

  The pressure filtration device (20) includes a casing (24), a crucible (26), a filter unit (28), and the like.

  The casing (24) is a rectangular casing made of a heat-resistant material such as metal, and an upper opening (24a) and a lower opening (24b) are provided on both upper and lower surfaces thereof. A crucible (26) is detachably attached to the casing (24) from the upper opening (24a), and a filter unit (28) is provided between the lower opening (24b) and the crucible (26). Is intervening.

  Further, around the crucible (26) attached in the casing (24), a heater (30) for heating or keeping the crucible (26) at a predetermined high temperature is disposed, and the crucible ( A heat insulating material (not shown) is filled in the casing (24) excluding the portion where the heater (26) and the heater (30) are attached.

  Further, the upper opening (24a) of the casing (24) includes a lid (32) for sealing the upper part of the crucible (26) attached in the casing (24), a fixing clamp (34) and a fixing handle. A gas pipe (38) for press-fitting air or inert gas (for example, nitrogen) into the crucible (26) is attached to the lid (32). It has been. The gas pipe (38) is connected to a gas supply source such as a gas cylinder (not shown) and a compressor that pressurizes and supplies the gas, including these devices connected to the gas pipe (38), It functions as a “pressurizing means” as a whole.

  The crucible (26) is a substantially cylindrical container made of a highly heat-resistant material such as graphite and having an open top surface. The crucible (26) accommodates molten aluminum in the interior or melts the Al ingot introduced into the interior. To prepare a molten aluminum (see FIG. 2).

  In the lower part of the crucible (26), a reduced diameter part (26a) whose side wall is tapered toward the center of the bottom surface is formed, and an opening (26b) is provided in the bottom center part. . With such a structure, when the molten aluminum accommodated in the crucible (26) is subjected to pressure filtration, the molten metal is easily collected into the opening (26b).

  The entire inner surface of the crucible (26) is covered with a release layer (40) formed of a thin film such as boron nitride. Here, the boron nitride (boron nitride; BN) forming the release layer (40) is a chemically stable substance having excellent stability at a high temperature of 700 ° C. or higher and thermal shock resistance, and is a solid lubricant. It functions as. By providing such a release layer (40), it is possible to prevent the molten aluminum accommodated in the crucible (26) from adhering to the inner wall of the crucible (26).

  As a method of forming the release layer (40) made of boron nitride on the inner surface of the crucible (26), boron nitride dispersed in a solvent and a high heat-resistant binder such as alumina cement are put in the crucible (26). Examples thereof include a method of forming a release layer (40) by uniformly spraying and then evaporating the solvent.

  A thermocouple (not shown) for measuring the temperature of the molten aluminum accommodated in the crucible (26) is attached to the crucible (26).

  The filter unit (28) is attached to the opening of the crucible (26) described above, and is for filtering the molten aluminum contained in the crucible (26) to capture inclusions, as shown in FIG. Further, it is composed of a lower member (42), a filter (44), and an upper member (46).

  The lower member (42) is a short cylindrical member formed of a heat insulating material. A through hole (42a) through which the molten aluminum passes is formed at the center of the lower member (42), and the inner diameter of the through hole (42a) is increased in the through hole (42a). The filter fitting hole (42b) and the upper member fitting hole (42c) are continuously provided in this order toward the upper end surface of the lower member (42).

  The filter (44) is a disc-shaped porous body formed of a high heat-resistant material such as porcelain, ceramics, quartz, graphite and alumina and having an outer diameter substantially the same as the inner diameter of the filter fitting hole (42b). Yes, only the inclusions in the molten aluminum are captured by pores having a diameter of about 50 μm to 200 μm, and the molten aluminum is allowed to pass through.

  The upper member (46) is a disk-shaped member that is formed of the same heat insulating material as the lower member (42) and has an outer diameter that is substantially the same as the inner diameter of the upper member fitting hole (42c). Is provided with a through hole (46a) having an inner diameter slightly smaller than the outer diameter of the filter (44).

  The measuring instrument (14) is a balance for measuring the weight of the molten aluminum after being pressure filtered by the Al metal or molten aluminum and the filter (44) put into the crucible (26).

  The control device (16) is connected to the measuring device main body (12) and the measuring device (14) via a wiring (not shown), and controls the temperature of the heater (30) and the pressure increase / decrease in the crucible (26) by the pressurizing means. A rectangular main body (16a) in which a control circuit such as a relay (not shown) is stored, and a main body for storing or displaying measurement data of a measuring instrument (14) and a sensor (not shown) And a display / operation panel (16b) installed on the upper surface. As with the measurement device main body (12), a caster (16c) is also attached to the bottom surface of the control device (16) so that it can move.

  Next, when the amount of inclusions in the molten aluminum is measured using the above-described inclusion amount measuring apparatus (10) of the present invention, first, as shown in FIG. After the filter (44) is fitted into the filter fitting hole (42b) of 42), the upper member (46) is fitted into the upper member fitting hole (42c) to assemble the filter unit (28).

  Subsequently, the filter unit (28) is attached to the position of the lower opening (24b) in the casing (24), and the crucible (26) is attached to the upper surface of the filter unit (28). At this time, the opening (26b) of the crucible (26) communicates with the lower opening (24b) of the casing (24) via the filter (44).

  Subsequently, a predetermined amount of Al ingot or molten aluminum (4 kg in this embodiment) is weighed and put into the crucible (26), and the lid (32) is attached to the upper surface of the crucible (26) for fixing. The lid (32) is fixed to the upper surface of the casing (24) by the clamp (34) and the fixing handle (36) to seal the crucible (26), and the heater (30) is controlled by the control device (16). Then, the crucible (26) is heated so that the inside of the crucible (26) has a predetermined temperature higher than the melting point of Al (specifically, about 670 ° C. or higher).

  Subsequently, when the temperature in the crucible (26) is stabilized at a predetermined set temperature, the control device (16) controls the pressurizing means, and the air is passed through the inert gas pipe (38) into the crucible (26). Alternatively, an inert gas is injected and almost all of the molten aluminum in the crucible (26) is pressure filtered at a predetermined pressure. Here, the pressurizing pressure in the crucible (26) is set so that inclusions captured by the filter (44) do not flow out of the filter (44). Then, the molten aluminum passes through the filter (44) and is stored in the molten metal tray (22), and inclusions are captured in the filter (44).

  Then, the amount of inclusions is quantified by measuring the weight of the molten aluminum accumulated in the molten metal receiving tray (22) with a measuring instrument (14) and obtaining the weight difference between the molten aluminum before and after pressure filtration.

  Table 1 shows the results of repeatedly measuring the amount of inclusions in the same lot of commercially available AD12.1 alloy defined by JIS H2118 using the inclusion amount measuring apparatus (10) of the present invention. The test was performed under the conditions of a measurement sample weight of 4 kg, a molten metal temperature of 710 ° C., and a pressure in the crucible (26) of 0.07 MPa. Moreover, in all the inclusion amount measurement examples shown below, the quantified amount of inclusion is shown as a residue ratio, that is, a weight ratio (% by weight) of inclusions in the entire molten aluminum.

表１が示すように、本発明の介在物量測定装置(10)を用いて同一ロットつまり同じＡｌ合金中に含まれる介在物量を繰返し測定した場合、得られる測定値にバラツキが少なく、再現性のよいことがうかがえる。

As Table 1 shows, when the amount of inclusions contained in the same lot, that is, the same Al alloy is repeatedly measured using the inclusion amount measuring apparatus (10) of the present invention, the obtained measurement values have little variation and reproducibility. I can see good things.

  Further, FIG. 3 shows that the ingot sample is cast by adding a predetermined amount of Dalai powder (cutting powder) equivalent to AD12.1 alloy to commercially available AD12.1 alloy of the same lot, and the inclusion amount measuring apparatus (10) of the present invention It is the result of using and measuring the amount of inclusions in the ingot sample. The test was performed under the conditions of a measurement sample weight of 4 kg, a molten metal temperature of 712 ° C., and a pressure in the crucible (26) of 0.07 MPa.

  As shown in FIG. 3, the amount of inclusions in the molten aluminum increases with an increase in the amount of added dairy powder, indicating that there is a high correlation between them.

  As described above, in the inclusion amount measuring apparatus (10) of the present invention, since the high heat-resistant release layer (40) is formed on at least the inner surface of the crucible (26), aluminum is formed on the inner surface of the crucible (26). The molten metal hardly adheres and remains, and almost all of the molten aluminum charged in the crucible (26) can be filtered.

  In addition, since almost all of the molten aluminum charged in the crucible (26) is pressure filtered with the filter (44), the end point of the pressure filtration is clear, and the measurement operation of each measurer varies. Not likely to occur. Therefore, the amount of inclusions in the molten aluminum can be measured accurately and with good reproducibility regardless of the number of measurements and the difference of the measurer.

  Furthermore, since the amount of inclusions in the molten aluminum can be easily determined from the weight difference between the molten aluminum before and after filtration, it is not necessary to prepare a calibration curve or the like, and it can be measured quickly and easily.

  Since the inclusion amount measuring device (10) does not include a fragile member, the device has high durability and can sufficiently withstand use at the manufacturing site.

  In the above example, the crucible (26) is formed of a high heat-resistant material such as graphite, and the release layer (40) made of boron nitride is provided on the entire inner surface. The entire crucible (26) may be formed of boron nitride without providing (40) separately. That is, as long as the crucible (26) has heat resistance capable of accommodating the molten aluminum and the surface layer on the inner surface functions as a solid lubricant, the aspect may be any.

  Moreover, although the case where the measuring instrument (14) is provided independently is shown, this measuring instrument (14) may be interposed between the lower part of the frame (18) and the molten metal tray (22). By disposing the measuring instrument (14) at such a position, it becomes possible to obtain a change with time in the filtration weight of the molten aluminum accompanying pressure filtration, that is, a filtration curve.

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to the examples.

  Prepare the same lot of commercially available AD12.1 alloy specified in JIS H2118 as a test sample, and use the above-mentioned inclusion amount measuring device (10) to measure a sample weight of 4 kg, a molten metal temperature of 710 ° C., and a crucible (26). Under the condition of pressure and pressure of 0.07 MPa, the amount of inclusions in the molten aluminum was measured three times, and the average value, standard deviation, and coefficient of variation were calculated. The obtained results are shown in Table 2.

[Comparative example]
The crucible (26) has the same conditions and methods as in the above-described embodiment, except that no crucible (26) is coated on the inside, that is, a crucible (26) formed only of graphite not forming the release layer (40). Was used to measure the amount of inclusions in the molten aluminum, and the average value, standard deviation, and coefficient of variation were calculated. The obtained results are shown in Table 2.

表２より、実施例では、測定データの変動係数が小さく、３回行なった介在物量の測定データ間でバラツキが極めて少ない、つまり再現性の高いことがうかがえる。これに対し、比較例では、測定データの変動係数が大きく、実施例に比べて、３回行なった介在物量の測定データ間でバラツキが大きい。また、同一試料を用いたにもかかわらず、比較例のほうが実施例よりも残渣率すなわちアルミニウム溶湯中の介在物量が多い結果となっている。

From Table 2, it can be seen that in the example, the variation coefficient of the measurement data is small, and there is very little variation between the measurement data of the amount of inclusions performed three times, that is, the reproducibility is high. On the other hand, in the comparative example, the coefficient of variation of the measurement data is large, and the variation between the measurement data of the amount of inclusions performed three times is large compared to the example. Even though the same sample was used, the comparative example had a higher residue rate, that is, the amount of inclusions in the molten aluminum than the example.

  Such a difference is caused by the presence or absence of the release layer (40) on the inner surface of the crucible (26). That is, in the embodiment, since the release layer (40) is provided on the inner surface of the crucible (26), when the molten aluminum in the crucible (26) is pressure-filtered, the molten aluminum becomes the wall surface of the crucible (26). It is possible to filter almost the entire amount of molten aluminum charged in the crucible (26). On the other hand, in the comparative example, since the release layer (40) is not provided on the inner surface of the crucible (26), when the molten aluminum in the crucible (26) is pressure-filtered, the molten aluminum is converted into the crucible (26). The total amount of molten aluminum that has adhered to and remains on the wall of the steel and put into the crucible (26) cannot be completely filtered. Therefore, the variation between the measurement data is increased, and the molten aluminum remaining on the wall surface of the crucible (26) is counted as inclusions, so that the amount of inclusions is measured more than in the example.

  Thus, the inclusion amount measuring apparatus (10) of the present invention can measure the amount of inclusions in the molten aluminum with high accuracy and good reproducibility.

  If the present invention is not only a molten aluminum but a molten metal for die casting having a melting point lower than that of Al, the amount of inclusions mixed therein can be measured quickly and easily with good reproducibility.

It is a block diagram which shows the inclusion amount measuring apparatus of one Example of this invention. It is a perspective view which shows the crucible and filter unit of one Example of this invention. It is a correlation test graph which shows the correlation with the amount of added Dalai powder and a residue rate.

Explanation of symbols

(10) ... Inclusion amount measuring device
(12) ・ ・ ・ Measurement device body
(14) ・ ・ ・ Weighing instrument
(16) ... Control device
(18) ・ ・ ・ Frame
(20) ... Pressure filtration device
(22) ... Molten saucer
(24) ... Casing
(26) ・ ・ ・ Crucible
(26b) ・ ・ ・ Opening
(28) ・ ・ ・ Filter unit
(30) ・ ・ ・ Heater
(32) ... Lid
(34) ・ ・ ・ Fixing clamp
(36) ・ ・ ・ Fixing handle
(38) ・ ・ ・ Gas piping
(40) ・ ・ ・ Releasing layer
(42) ・ ・ ・ Lower member
(44) ・ ・ ・ Filter
(46) ... Upper member

Claims (3)

Preparing a molten aluminum in a crucible in which a heat-resistant release layer is formed at least on the inner surface and a filter is attached to an opening provided on the bottom surface;
Pressurize the molten aluminum in the crucible and filter the whole amount with the filter,
A method for measuring the amount of inclusions in a molten aluminum, wherein the amount of inclusions is measured by the difference in weight of the molten aluminum before and after filtration. A crucible having a heat-resistant release layer formed at least on the inner surface thereof and an opening provided on the bottom surface thereof;
A filter that is attached to the opening of the crucible and filters the molten aluminum contained in the crucible;
A pressurizing means for pressurizing the molten aluminum contained in the crucible;
An apparatus for measuring the amount of inclusions in molten aluminum, comprising a measuring instrument for measuring the weight of the molten aluminum before and after filtration.   The said amount of release layer is comprised with the boron nitride, The inclusion amount measuring apparatus in the molten aluminum of Claim 2 characterized by the above-mentioned.

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