JP4217560B2 - Aluminum alloy continuous casting rod manufacturing equipment - Google Patents

Description

The present invention relates to apparatus for producing A aluminum alloy continuously cast bar.

  In general, horizontal continuous casting of metal produces a cylindrical, prismatic or hollow column-shaped long ingot from a molten metal through the following process. That is, the molten metal contained in the tundish for storing the molten metal is placed almost horizontally through the refractory passage and enters the forcedly cooled cylindrical mold, where it is cooled to the outside of the molten metal main body. A solidified shell is formed on the surface. A coolant such as water is directly radiated to the ingot drawn from the mold, and the ingot is continuously drawn while solidification of the metal proceeds to the inside of the ingot. Such a horizontal continuous casting of metal inevitably has a difficult point in principle.

  The first difficult point is that the mold is installed so that the central axis is almost horizontal, so that the molten metal in the mold is pressed against the inner wall below the mold by gravity, so that the cooling effect in the mold is reduced. An imbalance of the cooling effect occurs, which works strongly at the bottom and weakly at the top. As a result, the final solidification position shifts upward from the central axis of the continuous casting rod, so that an ingot having a homogeneous structure cannot be obtained.

  And the second difficult point is that lubricating oil for preventing seizure of the molten metal to the mold wall is injected from the inner peripheral wall of the inlet end of the mold. The lubricating oil is pushed up from the lower wall surface to the upper wall surface due to the difference in gravity between the upper surface and the lower surface of the ingot. In addition, the decomposition gas generated by heating the lubricating oil also rises to the upper wall surface, and the lubrication interface existing between the molten metal and the solidified surface constituting the outer peripheral surface of the ingot is inhomogeneous. It is to become. Since the molten metal and the mold wall are in contact with each other below the mold as described above, there is no substantial clearance between the solidified shell and the mold wall, and the molten metal and the ingot outer peripheral surface are in contact with the inner surface of the mold. If the lubricating oil does not flow between the solidified surface and the molten metal seizes on the inner surface of the mold, the solidified shell is broken and the unsolidified molten metal flows out. Tearing work becomes impossible. On the other hand, since the lubricating oil is excessive in the upper part of the mold, the molten metal is not sufficiently cooled by the mold, and the unsolidified molten metal is blown out from the upper part of the ingot.

Several solutions have been proposed in the past to overcome this essential problem in the horizontal continuous casting of metal. For example, in order to avoid excessive supply of lubricating oil to the upper part of the mold, a method of providing pores and grooves on the inner wall surface of the mold has been proposed.
Japanese Patent Publication No. 8-32356

  However, since the adjustment of conditions such as the injection amount of the lubricating oil, the casting speed, and the casting temperature in the tundish are very delicate, the conventional method including the proposal of the above-mentioned Patent Document 1 is particularly an actual manufacturing operation. Since these conditions are complicatedly related to the management, it is difficult to suppress fluctuations in the casting surface of the continuous cast bar, and as a result, seizure, breakout, pits and the like that cause casting defects are likely to occur.

The present invention provides an aluminum alloy continuous cast bar manufacturing apparatus that manufactures a high quality aluminum alloy continuous cast bar while suppressing defects in the casting surface and occurrence of breakout in view of the above-described situation in conventional horizontal continuous casting. To do.

The present invention is as follows.
(1) a molten aluminum alloy is supplied from the dissolve furnace, after the solidification ingot casting section having a cylindrical mold and cooling means, substantially horizontally at the lead driver this solidified ingot from the cylindrical mold In an aluminum alloy continuous cast bar manufacturing apparatus that pulls out and manufactures an aluminum alloy continuous cast bar, a detection unit that detects the range of the Si-rich structure formed on the aluminum alloy continuous cast bar drawn from the cylindrical mold, and this detection A determination unit that compares the detection signal from the detection unit with a predetermined determination condition, and the detection signal from the detection unit falls within a predetermined determination condition based on the determination signal from the determination unit The apparatus for producing an aluminum alloy continuous cast bar characterized by comprising a control unit for controlling the melt temperature of the melting furnace, the cooling means for the casting part, and the drawing speed of the drawing drive part.
( 2 ) The above-mentioned ( 1) , characterized in that a Ca insertion unit controlled by the control unit is provided so that the detection signal from the detection unit falls within a preset determination condition based on the determination signal from the determination unit. The manufacturing apparatus of the aluminum alloy continuous casting rod described in 1.).
( 3 ) An analysis unit that outputs a Ca amount measurement data signal obtained by composition analysis of the cast aluminum alloy continuous cast bar to the determination unit is provided, and the control unit includes the Ca amount measurement data signal and preset determination conditions. Based on the determination signal from the determination unit that compares with the above, the Ca charging unit is controlled so that the amount of Ca falls within a predetermined determination condition. The aluminum alloy continuous cast bar according to ( 2 ) above, Manufacturing equipment.

According to the present invention, it is possible to cast an aluminum alloy continuous cast bar having a Si-rich textured portion having a thickness of 20 μm or more on the surface of a side surface having an angle at the center (center angle) of at least 30 degrees or more.
Then, the Si-rich structure formed on the upper surface of the aluminum alloy continuous cast bar is seized and suppresses breakout, whereby the aluminum alloy continuous cast bar can be stably cast.

The aluminum alloy continuous cast bar manufactured using the aluminum alloy continuous cast bar manufacturing apparatus of the present invention will be described.
The aluminum alloy continuous cast bar manufactured by the apparatus of the present invention uses a cylindrical mold that is held so that the central axis is substantially horizontal (substantially horizontal is the lateral direction) and is provided with forced cooling means. Manufactured by a horizontal continuous casting method, the diameter can be in the range of 10 mm to 100 mm. Although it is possible to deal with other than the above diameter range, industrially post-process plastic processing, for example, forging, roll forging, drawing processing, rolling processing, impact processing, etc. are made small and inexpensive. For this reason, the diameter is preferably in the range of 10 mm to 100 mm. When casting by changing the diameter, it can be handled by exchanging with a removable cylindrical mold having an inner diameter corresponding to the diameter, and changing the melt temperature and casting speed accordingly. Change the cooling water and lubricating oil settings as necessary.

As shown in FIGS. 1 (a) and 1 (b), the aluminum alloy continuous cast rod (101) according to the present invention has an angle [center angle (103)] at the center (102) of 30 degrees or more (preferably 40). A band-shaped Si-rich structure (104 Is an aluminum alloy continuous cast bar. This belt-like Si-rich structure (104) is preferable because it can suppress the ejection of the unsolidified molten metal due to friction with the mold surface and does not hinder the plastic processing in the subsequent process. However, if the central angle (103) is less than 30 degrees and the thickness (102) is less than 20 μm, the above effect cannot be obtained sufficiently. In addition, the angle at which the Si-rich structure portion (104) is formed is preferably large, but the casting conditions become so severe.

In the present invention, the Si-rich structure and its thickness are defined as follows.
First, in order to obtain the thickness, for example, the tissue is observed by the following method.
(A) Sampling location / method / pretreatment of sample Randomly withdraw the sample from the manufactured aluminum alloy continuous casting rod (101), and 2 mm from the side surface corresponding to the upper part of the mold of the aluminum alloy continuous casting rod (101) A sample piece (306) (see FIG. 3B) having a square to 5 mm square is cut out. This sample piece (306) is sliced into thin pieces with a microtome to obtain a sample for observation of a cross section in the radial direction. The microtome is used because the observation surface corresponds to the very surface of the ingot, and normal cutting causes sag on the observation surface, so that good observation cannot be performed. If this can be overcome, other means may be used. .
Similarly, a small piece is cut out from each side of the side surface in the circumferential direction and used as a sample.

(B) Measuring device / measuring conditions Using an FE-AES (field emission Auger electron microscope) device, the element distribution of Al or Si in the radial cross section is obtained. As the FE-AES apparatus, for example, MICROLAB-310F (manufactured by VG) can be used. The observation conditions are, for example, acceleration voltage: 10 kV, sample current: 0.8 nA to 2.7 nA, and magnification: x1000.

  A field emission Auger electron microscope was used for surface observation, but it can also be measured with a secondary electron microscope or EPMA.

(C) How to read the thickness and other information of the Si-rich structure portion The image of the field emission Auger electron microscope image of the sample piece (306) taken from the aluminum alloy continuous casting rod (101) in FIG. A schematic diagram is shown in FIG. On the field emission Auger electron microscope image, the area occupancy of primary crystal α-Al (303) is determined for an arbitrary 10 μm square area from the ingot surface to the ingot center, and the area is less than 50%. Is the Si-rich microstructure (104), and the width of the region from the ingot surface to the center of the ingot is the thickness (302) of the Si-rich microstructure (104).
Here, the area ratio of the primary crystal α-Al (303) calculated from the point calculation method for the region specified as described above from the obtained field emission Auger electron microscope image is defined as the area occupation ratio.

The average particle diameter of Si particles the average diameter of the Si particles of Si-rich tissue section read by the image processing from the field emission Auger electron microscope image (104) (304), included in the fine Si tissue And

In the aluminum alloy continuous cast rod (101) according to the present invention, as shown in FIG. 3 (c), a fine Si structure containing primary α-Al (303) having a cross-sectional area area occupancy of less than 50%. It is preferable that When the area occupancy of the primary crystal α-Al (303) is less than 50%, the formed structure has a higher hardness than portions other than the fine Si structure, and the stable operability of casting is further improved. Is preferred.

  The average particle diameter of Si particles contained in the fine Si structure is preferably 0.1 μm to 5 μm. When the average particle size is in the above range, the formed fine Si structure makes the solidified shell formed on the side surface of the aluminum alloy continuous casting rod stronger and can suppress the ejection of unsolidified molten metal due to friction with the mold surface. preferable. Moreover, since it does not become an obstacle of the plastic processing of a post process, it is preferable. The surface having a fine Si structure has a metallic luster.

The aluminum alloy continuous casting rod according to the present invention can suppress the occurrence of seizing of the ingot on the inner surface of the mold, tearing of the ingot, or blowing out of the molten aluminum alloy during a long casting operation. As a result, the frequency of adjustment of operating conditions such as the amount of lubricating oil supplied and the casting speed can be suppressed, and stable operation can be performed.

The action mechanism can be estimated as follows.
Since the aluminum alloy continuous cast bar according to the present invention has a Si-rich textured portion with a thickness of 20 μm or more on the surface of the side surface having an angle at the center (center angle) of 30 degrees or more, the surface hardness is a conventional aluminum alloy continuous. It is relatively hard compared to the cast bar. As a result, it can be considered that the solidified shell becomes stronger with respect to the contact resistance between the ingot and the inner wall of the mold, and casting defects such as seizure hardly occur. Moreover, the part which has fine Si structure | tissue has a metallic luster, and the hardness of the part is high compared with the other part. It is considered that the upper part of the cylindrical mold held almost horizontally is insufficiently cooled because the lubricating oil is in an excessive state. When the Si-rich structure is formed in the part corresponding to this part of the aluminum alloy continuous cast bar, the solidification state above the mold, that is, the upper part of the ingot is stable, and the blowout of the unsolidified molten metal can be suppressed. Can think.

In the aluminum alloy continuous cast bar according to the present invention, Ca is 0.003% by mass or more (more preferably 0.003% by mass to 0.05% by mass, and further preferably 0.006% by mass or more, that is, 0.006%. It is preferable to contain it. This is because the hardness of the ingot surface can be made harder. As a result, the effect of the above-described action can be further enhanced.

The aluminum alloy continuous cast bar according to the present invention is used as a material for post-process plastic processing, for example, forging, roll forging, drawing, rolling, impact processing and the like. Alternatively, it is used as a material for machining such as bur machining and drilling. In this case, after casting, the fine Si structure is removed by peeling as needed before the post-process. At this time, the aluminum alloy continuous cast bar according to the present invention can be processed without any problem because the Si-rich structure does not have a significant difference in hardness compared to a cutting tool used for peeling processing, such as a cutting tool. Rather, since the chips are divided at the Si rich structure, it is possible to suppress processing troubles such as the chips entangled with the cutting tool. As a result, the aluminum alloy continuously cast rod of the present invention will become what machinability is improved, finished state of the peeling process becomes favorable, forging of forging process in the subsequent step is improved, dimensional accuracy quality Improvement of mold life and mold life. At this time, the aluminum alloy continuous cast rod is peeled on the surface, and as a result, the surface roughness Rmax is 50 μm or less, and no tool mark defect remains on the surface. Here, the tool mark defect is a scratch that is detected by an appearance inspection and is generated when a chip or the like is inserted into a cutting tool such as a cutting tool used in a peeling process.

  In addition, the aluminum alloy continuous cast bar exhibits an extremely smooth casting surface including a portion having a strong metallic luster at the upper part of the outer peripheral surface, so that there is no cavity defect inside the ingot and a good forging material It can be.

The aluminum alloy continuous cast rod according to the present invention can also obtain mechanical characteristics that can withstand forming processing as a subsequent step by performing an appropriate heat treatment without performing peeling processing.

An example of the apparatus of the present invention and a manufacturing method using the apparatus will be described.
As the horizontal continuous casting method used in the present invention, a known horizontal continuous casting method can be used. For example, a gas is applied to the inner wall surface of a cylindrical mold that is held so that the central axis is substantially horizontal and has a forced cooling means. Supplying one or more fluids selected from the liquid lubricant and the thermally decomposed gas, and supplying a molten aluminum alloy containing Si to one end of the cylindrical mold to form a columnar metal melt main body. An ingot formed by solidifying the columnar metal melt main body with a cylindrical mold can be a horizontal continuous casting method in which the ingot is drawn from the other end of the cylindrical mold.

FIG. 2 shows an example of the vicinity of the mold of the aluminum alloy continuous cast bar manufacturing apparatus of the present invention.
The tundish (250) and the refractory plate so that the molten alloy (255) stored in the tundish (250) is supplied to the cylindrical mold (201) through the refractory plate (210). A cylindrical body (210) and a cylindrical mold (201) are arranged. The cylindrical mold (201) is held so that the mold center axis (220) is substantially horizontal. The cylindrical mold (201) has a forced cooling means inside the cylindrical mold (201) and a solidified at the outlet of the cylindrical mold (201) so that the molten alloy (255) becomes a solidified ingot (216). A forced cooling means for the ingot (216) is provided. In FIG. 2, a cooling water shower device (205) is provided as an example of means for forcibly cooling the solidified ingot (216). In the vicinity of the outlet of the cylindrical mold (201), a drawing drive device (not shown) is installed so that the forcibly cooled solidified ingot (216) is drawn at a constant speed and continuously cast. ing. Furthermore, a synchronized cutting machine (not shown) for cutting the drawn aluminum alloy continuous cast bar into a predetermined length is provided.

As shown in FIG. 2, the cylindrical mold (201) is held so that the mold center axis (220) is substantially horizontal, and the mold wall surface is passed through the cooling water (202) into the mold cooling water cavity (204). A forced cooling means for the mold that forms the solidified shell on the surface of the columnar metal melt (215) filled in the cylindrical mold (201) by cooling and removing heat from the surface in contact with the cylindrical mold (201); A forced cooling means for discharging the cooling water from the cooling water shower device (205) so as to directly apply the cooling water to the solidified ingot (216) at the end of the mold outlet side to solidify the columnar metal melt (215) in the mold. It is a cylindrical mold. Furthermore, the cylindrical mold (201) is connected to the tundish (250) through a refractory plate-like body (210) at one end opposite to the jet port of the cooling water shower device (205). In FIG. 2, cooling water for forcibly cooling the cylindrical mold (201) and cooling water for forcibly cooling the solidified ingot (216) are supplied via the cooling water supply pipe (203). Cooling water can be provided separately for each.
It is preferable that the forced cooling means of the cylindrical mold (201) and the cooling water shower device (205) can each be controlled by a control signal.

  Contact between the cylindrical mold (201) and the refractory plate-like body (210) from the position where the extended line of the central axis of the jet port of the cooling water shower device (205) hits the surface of the cast solid ingot (216) The length to the surface is referred to as an effective mold length (see symbol L in FIG. 4), and the effective mold length L is preferably 15 mm to 70 mm. This is because a Si-rich structure having a thickness of 20 μm or more is sufficiently formed on the surface of the side surface having an angle (center angle) of 30 degrees or more at the center of the aluminum alloy continuous cast bar. If the effective mold length L is less than 15 mm, casting is impossible because a good film is not formed. If the effective mold length L exceeds 70 mm, there is no effect of forced cooling, and solidification by the mold wall becomes dominant, and a cylindrical mold ( 201) and the molten alloy (255) or solidified shell increase in contact resistance, which is not preferable because casting becomes unstable, such as cracking in the casting surface or tearing inside the mold.

  The material of the cylindrical mold (201) is preferably one or a combination of two or more selected from aluminum, copper, or alloys thereof. A combination of materials can be selected in terms of thermal conductivity, heat resistance, and mechanical strength.

Further, a mold in which a permeable porous material (222) having self-lubricating property is loaded in a ring shape on the surface of the cylindrical mold (201) that contacts the molten alloy (255) is preferable. The ring shape is a state in which the entire inner wall surface (221) of the cylindrical mold (201) is attached in the circumferential direction. The permeability of the permeable porous material (222) is 0.005 [L / (cm ² × min)] to 0.03 [L / (cm ² × min)] [more preferably 0.007 [L / ( cm ² × min)] to 0.02 [L / (cm ² × min)]. It is preferable that The thickness of the permeable porous material (222) to be attached is not particularly limited, but is preferably 2 mm to 10 mm (more preferably 3 mm to 8 mm). This is because a Si-rich structure having a thickness of 20 μm or more is sufficiently formed on the surface of the side surface having an angle (center angle) of 30 degrees or more at the center of the aluminum alloy continuous cast bar. As the permeable porous material (222), for example, graphite having an air permeability of 0.008 [L / (cm ² × min)] to 0.012 [L / (cm ² × min)] can be used. Here, the air permeability is obtained by measuring the air flow rate per minute of air having a pressure of 2 (kg / cm ² ) with respect to a test piece having a thickness of 5 mm.

It is preferable to use the cylindrical mold (201) in which the permeable porous material (222) is attached to 5 to 15 mm of the effective mold length L. This is because a Si-rich structure having a thickness of 20 μm or more is sufficiently formed on the surface of the side surface having an angle (center angle) of 30 degrees or more at the center of the aluminum alloy continuous cast bar. Refractory steel plate-like member (210), the tubular mold (201), preferably disposed O-ring (213) on the mating surface of the permeable porous material (222).

  The shape of the inner wall of the radial cross section of the cylindrical mold (201) may be a triangle, a rectangular cross-sectional shape, or a shape having an irregular cross-sectional shape having no symmetry axis or plane of symmetry, in addition to a circular shape. Or when forming a hollow ingot, what hold | maintained the core inside the casting_mold | template may be used. The cylindrical mold (201) is a cylindrical mold with both ends open, and an alloy is formed from one end to the cylindrical interior via a pouring port (211) drilled in the refractory plate-like body (210). The molten metal (255) enters, and the solidified ingot (216) is pushed out or pulled out from the other end.

  The inner wall surface of the mold is formed at an elevation angle of 0 degrees to 3 degrees (more preferably 0 degrees to 1 degree) with the mold center axis (220) toward the drawing direction of the solidified ingot (216). If the elevation angle is less than 0 degrees, the solidified ingot (216) receives resistance at the mold exit when it is pulled out from the cylindrical mold (201). On the other hand, if it exceeds 3 degrees, casting becomes impossible. The contact with the molten metal (215) becomes insufficient, and the heat removal effect from the molten alloy (255) or the solidified shell to the cylindrical mold (201) is reduced, resulting in insufficient solidification. As a result, remelting skin is generated on the surface of the ingot, or there is a high possibility that it may lead to casting trouble such as unsolidified molten alloy (255) being ejected from the end of the mold.

The tundish (250) includes a molten metal inflow portion (251) that receives the molten aluminum alloy adjusted to a prescribed alloy component by an external melting furnace or the like, a molten metal holding portion (252), and an outflow portion to the cylindrical mold (201). (253). Tundish (250) is maintained at a liquid level (254) of the tubular mold (201) a position higher than the upper surface of the molten alloy (255), and, in the case of multiple-casting, the cylindrical mold ( 201), the molten alloy (255) is stably distributed. The molten alloy (255) held in the molten metal holding part (252) in the tundish (250) is poured into the cylindrical mold (201) from the pouring port (211) provided in the refractory plate-like body (210). It is hot water.
The melting furnace or tundish (250) is preferably provided with a Ca charging device capable of controlling the charging amount with a control signal.

Refractory steel plate-like member (210) is provided for separating the tundish and (250) and a cylindrical mold (201), can be used a material having a refractory thermal insulation, for example, (Corporation) Examples include Nichias Lumiboard, Fosseco Insular, and Ibiden Fiber Blanket Board. The refractory plate-like body (210) has a shape that can form the pouring gate (211). One or more pouring gates (211) can be formed in a portion where the refractory plate-like body (210) protrudes inward from the inner wall surface (221) of the cylindrical mold (201).

  Reference numeral 208 denotes a fluid supply pipe for supplying fluid. The fluid can include a lubricating fluid. The fluid may be any one or two or more fluids selected from gas and liquid lubricant. The gas and liquid lubricant supply pipes are preferably provided separately. The fluid pressurized and supplied from the fluid supply pipe (208) is supplied to the gap between the cylindrical mold (201) and the refractory plate (210) through the annular passage (224). It is preferable that a gap of 200 μm or less is formed at a portion where the cylindrical mold (201) faces the refractory plate-like body (210). The gap is large enough to allow the fluid to flow out to the inner wall surface (221) of the cylindrical mold (201) so that the molten alloy (255) is not inserted. In the form shown in FIG. 2, the annular passage (224) is perforated on the outer peripheral surface side of the permeable porous material (222) attached to the cylindrical mold (201), and the pressure applied to the fluid. Is transmitted to the entire surface of the permeable porous material (222) that penetrates the inside of the permeable porous material (222) and contacts the molten alloy (255), and is applied to the inner wall surface (221) of the cylindrical mold (201). Supplied. In some cases, the liquid lubricant is heated to be decomposed gas and supplied to the inner wall surface (221) of the cylindrical mold (201).

  As a result, lubrication between the permeable porous surface of the cylindrical mold (201) and the outer peripheral surface of the columnar metal melt (215) main body and the solidified shell outer peripheral surface can be improved. By attaching the permeable porous material (222) in a ring shape, a better lubricating effect can be obtained, and a Si-rich structure with a thickness of 20 μm or more on the surface of the side surface with a central angle (central angle) of 30 degrees or more. An aluminum alloy continuous casting rod having a portion can be easily cast.

  The corner space (230) is formed by any one or more selected from the supplied gas, liquid lubricant, and gas decomposed from the liquid lubricant.

A manufacturing method using the apparatus of the present invention will be described.
In FIG. 2, the molten alloy (255) in the tundish (250) passes through the refractory plate (210), and the cylindrical mold (201) held so that the mold center axis (220) is substantially horizontal. ) And forcedly cooled at the outlet of the cylindrical mold (201) to become a solidified ingot (216). Since the solidified ingot (216) is drawn at a constant speed by a drawing drive device installed near the outlet of the cylindrical mold (201), it is continuously cast into an aluminum alloy continuous cast bar. The drawn aluminum alloy continuous cast bar is cut into a predetermined length by a synchronous cutting machine.

  At this time, the composition of the component and the temperature of the molten metal were set so that the surface of the side surface having a center angle (center angle) of 30 degrees or more had a Si-rich structure having a thickness of 20 μm or more. To do. Thereby, it is considered that the state of the solidification interface (217) of the molten columnar metal (215) is stabilized and the state of the corner space (230) is stabilized, and as a result, a stable casting operation can be performed. The effective mold length L of the cylindrical mold (201) can be set so as to have a Si-rich textured portion on the surface of the side surface having a central angle of 30 degrees or more.

The composition of the molten alloy (255) of the aluminum alloy stored in the tundish (250) will be described.
The composition contains 7 mass% to 14 mass% (more preferably 8 mass% to 13 mass%, more preferably 12 mass% to 13 mass%) of Si, and 0.003 mass% or more of metal Ca (more preferably). Is preferably 0.003% by mass to 0.04% by mass, and more preferably 0.003% by mass to 0.03% by mass. As other components, Fe is 0.1% by mass to 0.5% by mass, Cu is 2.0% by mass to 9.0% by mass, Mn is 0% by mass to 0.5% by mass, and Mg is 0.2% by mass. It is preferable that it is mass%-1.0 mass%.

  In particular, those containing 8% by mass to 13% by mass of Si have excellent mechanical properties and improved wear resistance due to hard Si because Al and Si in the ingot constitute a fine layered structure. This is preferable.

Here, the relationship between the content of Ca in the alloy and the amount added will be described.
When Ca inevitably mixed is present, the Ca amount appearing in the value obtained by analysis as the content in the alloy is (1) Ca inevitably mixed from the raw material (the mixed source is mainly used as the raw material). Metal Si.) And (2) Ca added to the molten metal. For example, what is detected in an ingot without addition of Ca is Ca inevitably mixed from the raw material, and when added, the difference from that is the amount of added Ca.

  In the present invention, the amount of Ca contained in the alloy is preferably 0.003% by mass or more. In particular, the amount of Ca to be added is more preferably 0.003% by mass or more. The total value of the added Ca amount and the inevitable Ca amount in the ingot is preferably 0.004% by mass or more, and more preferably 0.004% by mass to 0.05% by mass, and 0.005% by mass to 0%. More preferably, it is 0.05 mass%. This is because formation of the Si-rich structure is promoted and Si particles in the ingot are refined, so that mechanical characteristics are improved.

  Since unavoidably mixed Ca is included in the raw material metal Si, it is considered to be in the form of calcium silicate, while the added Ca does not form an oxide in the molten aluminum alloy. Since it is considered to exist, in order to promote the formation of the Si-rich structure part and to refine the Si particles in the ingot, the amount of Ca to be added is 0.003% by mass or more, more preferably 0.003. It is thought that it is preferable that it is mass%-0.03 mass%.

  The added Ca is preferably metallic Ca having a purity of 99.9% by mass or more. The shape is preferably granular for work. After completing the component adjustment for elements other than Ca, granular Ca is introduced into the molten metal. In order to prevent oxidation at the time of charging, it is preferable to load in a state wrapped with aluminum foil.

  The composition ratio of the alloy components of the ingot can be confirmed, for example, by a method using a photoelectric photometric emission spectroscopic analyzer (device example: PDA-5500 manufactured by Shimadzu Corporation, Japan) as described in JIS H 1305.

  The difference between the height of the liquid level (254) of the molten alloy (255) stored in the tundish (250) and the height of the upper inner wall surface (221) of the cylindrical mold (201) is 0 mm to 250 mm. (More preferably 50 mm to 170 mm). This is because the castability is stable because the pressure of the molten alloy (255) supplied into the cylindrical mold (201) and the lubricating oil and the gas in which the lubricating oil is vaporized are suitably balanced. This is because an aluminum alloy continuous cast bar having a Si-rich microstructure having a thickness of 20 μm or more on the surface of the side surface of 30 ° or more can be easily produced. By providing a level sensor to measure and monitor the height of the liquid level (254) of the molten alloy (255) in the tundish (250), the difference is accurately managed and maintained at a predetermined value. can do.

  As the liquid lubricant, vegetable oil which is a lubricating oil can be used. For example, rapeseed oil, castor oil, salad oil can be mentioned. These are preferable because they have a small adverse effect on the environment.

  The lubricating oil supply rate is preferably 0.05 mL / min to 5 mL / min (more preferably 0.1 mL / min to 1 mL / min). This is because a Si-rich structure having a thickness of 20 μm or more is sufficiently formed on the surface of the side surface having an angle (center angle) of 30 degrees or more at the center of the aluminum alloy continuous cast bar. If the supply amount is too small, a breakout of the solidified ingot (216) occurs due to insufficient lubrication, and if the supply amount is excessive, the excess is mixed into the solidified ingot (216) and becomes an internal defect. is there.

  The casting speed, which is the speed at which the solidified ingot (216) is drawn from the cylindrical mold (201), is preferably 200 mm / min to 1500 mm / min (more preferably 400 mm / min to 1000 mm / min). This is because a Si-rich microstructure having a thickness of 20 μm or more is sufficiently formed on the surface of the side surface having an angle (center angle) of 30 degrees or more at the center of the aluminum alloy continuous cast bar. This is because deterioration does not occur and the ingot structure can be made fine and uniform by a large cooling rate.

  The amount of cooling water discharged from the cooling water shower device (205) is preferably 5 L / min to 30 L / min (more preferably 25 L / min to 30 L / min) per mold. If the amount of cooling water is too small, the formation of a Si-rich structure having a thickness of 20 μm or more on the surface of the side surface having an angle (center angle) of 30 ° or more at the center of the aluminum alloy continuous cast rod becomes insufficient, resulting in breakout. Or the surface of the solidified ingot (216) may be remelted to form a non-uniform structure and remain as an internal defect. On the other hand, if the amount of cooling water is excessive, the heat removal from the cylindrical mold (201) is too large, and casting becomes impossible.

  The average temperature of the molten alloy (255) flowing from the tundish (250) into the cylindrical mold (201) is 600 ° C. to 750 ° C. (more preferably 640 ° C. to 680 ° C.). This is preferable because a Si-rich structure having a thickness of 20 μm or more is sufficiently formed on the surface of the side surface having a corner (center angle) of 30 ° or more at the center of the casting rod. If the temperature of the molten alloy (255) is too low, a coarse crystallized product is formed in the cylindrical mold (201) and before, and is taken into the solidified ingot (216) as an internal defect. On the other hand, if the temperature of the molten alloy (255) is too high, a large amount of hydrogen gas is taken into the molten alloy (255) and taken into the solidified ingot (216) as porosity, resulting in internal defects. .

FIG. 5 is a schematic configuration diagram of an example of the aluminum alloy continuous cast bar manufacturing apparatus 501 of the present invention.
The manufacturing apparatus 501 has a configuration shown in FIG. 2, a melting furnace 502 that generates molten aluminum alloy, a Ca charging device 503 that supplies Ca into the melting furnace 502, and a molten aluminum alloy from the melting furnace 502. The casting apparatus 504, the aluminum alloy continuous casting rod 101 cast by the casting apparatus 504, the drawer drive device 505 for pulling out the casting apparatus 504, and the Si formed on the surface of the aluminum alloy continuous casting rod 101 cast by the casting apparatus 504 A detection unit 506 that detects the range of the rich structure portion and outputs a detection signal; an analysis unit 507 that analyzes the composition of the aluminum alloy continuous casting rod 101 cast by the casting apparatus 504 and outputs a Ca amount measurement data signal; The set judgment condition is compared with the output signals from the detection unit 506 and the analysis unit 507, and the comparison judgment signal is compared. A determination unit 508 for outputting, based on this output, such as a determination unit 508, so as to be within a preset determination condition, and a control unit 509 for controlling each unit. The analysis unit 507 can be omitted. The control units 509 can be arranged in a distributed manner.

  The melting furnace 502 includes a heater (not shown) and a temperature detector (not shown), and the heater is controlled by the control unit 509 so that the temperature in the furnace is maintained at a predetermined temperature. Thus, the temperature in the furnace is detected and output to the control unit 509. Although not shown, each charging device (not shown) for supplying a metal for generating a molten aluminum alloy excluding Ca to the melting furnace 502 is provided. Each charging device and Ca charging device 503 are provided with a charging mechanism (not shown) and a charging amount detector (not shown), and each charging mechanism is controlled by the control unit 509 to melt each metal. At the same time, the input amount is detected by the input amount detector and output to the control unit 509. The casting apparatus 504 includes a lubrication unit (not shown), each cooling unit (not shown), and each temperature detector (not shown). The lubrication unit and each cooling unit are controlled by the control unit 509. As a result, the molten aluminum alloy is cooled to form an aluminum alloy continuous casting rod 101, and the temperatures in the tundish and the cylindrical mold are detected by each temperature detector and output to the control unit 509. Further, the drawing drive device 505 includes a speed detector that detects the drawing speed, and is controlled by the control unit 509 so that the aluminum alloy continuous casting rod 101 is pulled out from the casting device 504, and the speed detector (not shown). The drawing speed is detected and output to the control unit 509.

For example, the detector 506 may be any detector as long as it is a detector that can detect the difference between the Si rich structure portion of the aluminum alloy continuous casting rod 101 and other portions, and can detect the difference. Can do. For example, since the surface of the Si-rich tissue portion has gloss or the roughness of the surface is different, for example, a detector that detects reflectance, surface roughness, etc. is used to detect them. Can be mentioned. In particular, it is preferable to use a detector such as an optical type, an ultrasonic type, or a capacitance type because it can detect without contact. Since the detector detects the range of the Si-rich structure, it must have a function of covering the entire surface of the aluminum alloy continuous cast rod 101 to be inspected having the above properties or scanning the inspection range. is there.
From the detection unit 506, a detection signal corresponding to the detection position of the Si rich structure portion of the aluminum alloy continuous casting rod 101 and the detection result of the surface property is output and sent to the determination unit 508.

  A determination condition is set in the determination unit 508 in advance, and is compared with the detection signal related to the Si-rich tissue portion from the detection unit 506 or compared with the analysis result from the analysis unit 507, that is, the Ca amount measurement data signal. To do. For example, it is possible to perform processing for determining a region where a difference occurs in the surface property detection result as a boundary between the Si-rich tissue part and another part and detecting the range of the Si-rich tissue part. Further, the determination unit 508 has a control function of comparing and determining the determination condition and the detection signal and feeding back a control signal (casting condition adjustment signal) for controlling the casting condition based on the comparison determination result to the control unit 509. Yes.

The signal processing, determination processing, and condition setting processing may use analog signals or digital signals.
As the determination condition for the Si-rich microstructure, a reflectance or surface roughness in a range corresponding to a central angle of 30 degrees or more of the surface of the side surface of the aluminum alloy continuous cast rod 101 can be used as described above.

  Examples of casting control targets include the temperature of the molten aluminum alloy and the casting speed. Therefore, based on the detection signal of the aluminum alloy continuous casting rod 101 cast by the casting device 504 detected by the detection unit 506, for example, by increasing the temperature of the molten aluminum alloy, the range of the portion having the glossy portion is widened. Can do. The reason is presumed that the temperature difference between the molten aluminum alloy temperature and the solidification temperature gives a difference in the solidification state, and as a result, the formation of the glossy part can be controlled. It is estimated that the casting speed has a similar effect. The temperature of the molten aluminum alloy can be adjusted by controlling the heating temperature of the melting furnace 502, the warming heating during the supply to the tundish, the warming heating in the tundish, and the like. The casting speed can be adjusted by using a device capable of adjusting the forced cooling of the mold, the amount of cooling water from the cooling water shower device, the drawing speed of the drawing drive device 505, and the molten aluminum alloy temperature.

It is preferable to add a Ca addition amount to the casting control object because the degree of freedom in setting the casting conditions increases. As a means for adding Ca, as shown in FIG. 5, by adding a Ca charging device 503 to each charging device (not shown) for charging the raw material into the melting furnace 502, the input amount of the raw material and Ca Can be easily controlled in combination. The effect is estimated to be because the solidification temperature is lowered by the addition of Ca and the temperature difference between the molten metal temperature and the solidification temperature can be changed, so that the difference in the solidification state can be given, and as a result, the formation of the glossy part can be controlled. The Even if Ca is added directly to the tundish, the same effect can be obtained.
In order to manage the Ca addition amount with higher accuracy, an analysis unit 507 is provided to transfer data of the Ca amount measurement result obtained by composition analysis of the cast product to the determination unit 508, and the determination result of the range of the Si rich structure portion It is preferable to control the molten metal temperature, casting speed, and Ca addition amount based on the data on the Ca addition amount. This is because the range of the Si-rich microstructure can be controlled by ensuring that the Ca addition amount is 0.003% by mass or more.
As the composition analysis method, any method can be used as long as it can detect Ca, and the analysis can be performed from the surface immediately after casting, or the sample can be taken and measured offline. The thing whose measurement time is less than 1 hour is preferable. An example of the Ca content measurement is emission spectroscopy analysis.

When this apparatus is used, an aluminum alloy continuous cast bar having a Si-rich structure having a thickness of 20 μm or more on the surface of the side surface having a center angle (center angle) of at least 30 degrees or more can be easily produced.
And the Si rich structure part formed in the upper surface of an aluminum alloy continuous cast bar is seized, and an aluminum alloy continuous cast bar can be manufactured stably by suppressing breakout.
In addition, the manufacturing method of the aluminum alloy continuous casting rod using this apparatus is controlled by controlling the temperature difference between the molten metal temperature and the solidification temperature, or the temperature difference between the molten metal temperature and the solidification temperature and pulling out from the cylindrical mold. By controlling the drawing speed of the aluminum alloy continuous cast bar, it is possible to easily produce an aluminum alloy continuous cast bar having a Si-rich structure having a thickness of 20 μm or more on the side surface having a central angle of at least 30 degrees or more. it can.
And the Si rich structure part formed in the upper surface of an aluminum alloy continuous cast bar is seized, and an aluminum alloy continuous cast bar can be manufactured stably by suppressing breakout.

Next, examples of the present invention will be described, but the present invention is not limited to the examples.
[Examples 1 to 4]
0.003 mass% (Example 1), 0.006 mass% (Example 2), 0.01 mass% (Example 3), 0.03 of metal Ca in an aluminum alloy containing 12 mass% of Si The alloy melt added by mass% (Example 4) was continuously cast into a billet having a diameter of 30 mm using the apparatus shown in FIG. The permeable porous template using graphite permeability 0.01 [L / (cm ² × min)]. The casting conditions are as follows.
(1) Level difference between the melt level in the tundish and the upper surface of the mold inner wall: 150 mm
(2) Lubricating oil: rapeseed oil (3) Lubricating oil supply rate: 0.2 mL / min (4) Casting speed: 900 mm / min (5) Cooling water supply rate: 25 L / min (6) Melt temperature average in tundish : 660 ° C

[Comparative Example 1]
Horizontal continuous casting was performed under the same conditions as in Example 1 except that the addition of metal Ca was not performed.

For Example 1 to Example 4 and Comparative Example 1, FIG. 6 shows the state of casting trouble frequency (the number of trouble occurrences in 30-minute units) on the horizontal axis with the operation time as the horizontal axis. Casting troubles indicated a break in casting operation due to breakout or chigile. Immediately after the casting operation was stopped, the mold was changed and restarted.
In FIG. 6, a broken line (circle white broken line) 6A is Example 1, a broken line (triangular white broken line) 6B is Example 2, a broken line (square white broken line) 6C is Example 3, and a broken line (asterisk). A broken line 6D shows Example 4, and a broken line (black circle broken line) 6E shows Comparative Example 1.

  In each of Examples 1 to 4, the casting state was stabilized in 100 operations in each actual operation, and the occurrence of operation troubles such as blowing of molten alloy and tearing could be reduced. The obtained aluminum alloy continuous cast bar exhibited an extremely smooth casting surface including a portion having a strong metallic luster at the upper part of the outer peripheral surface, and no cavity defect was present inside the ingot.

  When the structure of this metallic luster portion was observed, it was found that it exhibited a fine Si structure containing primary α-Al having an area occupancy of less than 50%.

  In the casting of Comparative Example 1, the casting state was unstable and the surface state of the casting surface was fluctuated in a total of 100 operations in actual operation. The aluminum alloy continuous casting rod seizes to the inner surface of the mold, the aluminum alloy continuous casting rod tears, or the molten alloy blows out from the mold due to tearing. It was necessary to adjust at least one of the above, and the production efficiency was poor. In addition, when the surface of the obtained aluminum alloy continuous casting rod was observed with the naked eye, a periodic scaly pattern was observed on the upper casting surface, and large and small seizures were observed on the lower casting surface, indicating an abnormal surface condition. It affected deep inside the ingot.

  Regarding Examples 1 to 4 and Comparative Example 1, the analysis results of the alloy composition are shown in Table 1, and the measurement results of the Si-rich microstructure are shown in Tables 2 and 3.

[Examples 5 to 8]
0.003 mass% (Example 5), 0.006 mass% (Example 6) of metal Ca in an aluminum alloy containing 12 mass% Si, 4 mass% Cu, and 0.5 mass% Mg, The molten metal added with 0.01% by mass (Example 7) and 0.03% by mass (Example 8) was continuously cast into billets having a diameter of 50 mm using the apparatus shown in FIG. The permeable porous template using graphite permeability 0.01 [L / (cm ² × min)]. The casting conditions are as follows.
(1) Level difference between the melt level in the tundish and the upper surface of the mold inner wall: 170 mm
(2) Lubricating oil: rapeseed oil (3) Lubricating oil supply rate: 0.3 mL / min (4) Casting speed: 900 mm / min (5) Cooling water supply rate: 30 L / min (6) Melt temperature average in tundish : 660 ° C

[Comparative Example 2]
Horizontal continuous casting was carried out under the same conditions as in Example 5 except that no metal Ca was added.

For Examples 5 to 8 and Comparative Example 2, FIG. 7 shows the operating time on the horizontal axis and the state of casting trouble frequency on the vertical axis.
In FIG. 7, a broken line (round white broken line) 7A is Example 5, a broken line (triangular white broken line) 7B is Example 6, a broken line (square white folded line) 7C is Example 7, and a broken line (asterisk). A broken line 7D shows Example 8, and a broken line (black broken line) 7E shows Comparative Example 2.

The results of continuous casting in Example 5 to Example 8 were good, with the casting defects reduced drastically as in Example 1. In a total of 100 castings, the casting state was extremely stable, and operational troubles such as blowing and tearing of molten alloy could be reduced.

  Further, the hardness of the portion having a strong metallic luster formed on the upper surface of the casting surface was measured. The hardness of the ingot surface of Examples 5 to 8 to which metal Ca was added was relatively higher than that of Comparative Example 2 to which no metal Ca was added. In addition, the hardness of the metallic luster part seen in the one added with the metal Ca is higher than that of the other part, and this is formed in the part where the cooling is insufficient due to excessive lubrication above the mold. It is thought that the blowout from was able to be suppressed.

  When the structure of this metallic luster portion was observed, it was found that it exhibited a fine Si structure containing primary α-Al having an area occupancy of less than 50%.

  On the other hand, in the casting of Comparative Example 2, the casting state was unstable and the surface condition of the casting surface was varied in 100 times of casting. The aluminum alloy continuous casting rod seizes to the inner surface of the mold, the casting rod is broken, or the molten alloy blows out from the mold due to the tearing. The production efficiency was poor. In the case of no addition of metal Ca in Comparative Example 2, the upper casting surface has a periodic scaly pattern, and the structure cannot confirm the Si-rich structure and is not different from the structure inside the ingot. It was.

  For Examples 5 to 8 and Comparative Example 2, the analysis results of the alloy composition are shown in Table 1, and the measurement results of the Si-rich microstructure are shown in Tables 2 and 3.

  Table 4 shows the measurement results of the average particle diameter of the Si particles contained in the fine Si structures of Examples 1 to 8.

[Examples 9 to 12]
The air permeability is 0.008 [L / (cm ² × min)] (Example 9), 0.012 [L / (cm ² × min)] (Example 10), 0.001 [L / (cm ² × min)] (Example 11), 0.1 [L / (cm ² × min)] (Example 12), except that the permeable porous material was used. Casting was carried out.
In Examples 9 and 10, the same results as in Example 5 were obtained. In Example 11, there was no sudden increase in trouble to stop the operation, but the lubrication effect was insufficient, and seizure occurred on the surface of the casting surface, the ingot was broken, and the operation was unstable. It was. In Example 12, there was no sudden increase in troubles to stop the operation, but the lubricating oil became excessive, resulting in hot water coming out due to insufficient cooling, inclusion of inclusions in the casting surface or ingot, and operation. There was a tendency to become unstable.

It is explanatory drawing of the aluminum alloy continuous casting rod which concerns on this invention, (a) is the external appearance schematic of an aluminum alloy continuous casting rod, (b) is the cross-sectional schematic of the radial direction of an aluminum alloy continuous casting rod. It is a principal part schematic sectional drawing of an example of the manufacturing apparatus of this invention. It is explanatory drawing of Si rich structure of the aluminum alloy continuous casting rod which concerns on this invention, (a) is explanatory drawing of sampling of the sample piece from the cross section of the radial direction of an aluminum alloy continuous casting rod, (b) is the element of a sample piece An enlarged schematic diagram showing an example of a distribution map image, (c) is an enlarged schematic diagram showing another example of an element distribution map image of a sample piece. It is explanatory drawing of the effective mold length of the cylindrical mold in the manufacturing apparatus of FIG. It is a schematic block diagram which shows an example of the manufacturing apparatus of the aluminum alloy continuous casting rod of this invention. It is a graph which shows the data of Example 1-Example 4 of the aluminum alloy continuous cast bar concerning this invention. It is a graph which shows the data of Example 5-Example 8 of the aluminum alloy continuous cast bar concerning this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 Aluminum alloy continuous casting rod 102 Center of aluminum alloy continuous casting rod 103 Center angle 104 Si rich structure part 201 Cylindrical mold 202 Cooling water 203 Cooling water supply pipe 204 Mold cooling water cavity 205 Cooling water shower apparatus 208 Fluid supply pipe 210 Fire resistance Product-made plate-like body 211 Pouring port 213 O-ring 215 Columnar metal melt 216 Solidified ingot 217 Solidification interface 220 Mold central axis 221 Inner wall surface of cylindrical mold 222 Permeable porous material 224 Annular passage 230 Corner space 250 Tundish 251 Molten inflow portion 252 Molten holding portion 253 Outflow portion to cylindrical mold 254 Liquid surface level of molten alloy 255 Alloy molten metal 302 Thickness of Si-rich microstructure 303 Primary α-Al
304 Si particles 306 Sample piece 501 Manufacturing device 502 Melting furnace 503 Ca charging device 504 Casting device 505 Drawer drive device 506 Detection unit 507 Analysis unit 508 Determination unit 509 Control unit L Effective mold length

Claims (3)

The molten aluminum alloy supplied from the melting furnace is made into a solid ingot at a casting part equipped with a cylindrical mold and a cooling means, and then this solidified ingot is drawn almost horizontally from the cylindrical mold by a pulling drive part to obtain an aluminum alloy. In an aluminum alloy continuous cast bar manufacturing apparatus for manufacturing continuous cast bars,
A detection unit for detecting the range of the Si-rich structure formed on the aluminum alloy continuous casting rod drawn from the cylindrical mold;
A determination unit for determining by comparing a detection signal from the detection unit with a predetermined determination condition;
Control for controlling the molten metal temperature of the melting furnace, the cooling means of the casting part, and the drawing speed of the drawing drive part so that the detection signal from the detecting part falls within preset judgment conditions based on the judgment signal from the judging part provided the parts,
An apparatus for producing an aluminum alloy continuous cast bar characterized by the above. Based on the determination signal from the determination unit, according to claim 1, the detection signal from the detection portion is provided with a Ca-up unit controlled by the control unit so as to be within a preset determination condition, it is characterized by Aluminum alloy continuous cast bar manufacturing equipment. An analysis unit is provided that outputs a Ca amount measurement data signal obtained by composition analysis of a cast aluminum alloy continuous cast bar to the determination unit,
The control unit controls the Ca insertion unit based on a determination signal from the determination unit that compares the Ca amount measurement data signal with a predetermined determination condition, so that the Ca amount falls within the predetermined determination condition . The apparatus for producing an aluminum alloy continuous cast bar according to claim 2 .