WO2018034164A1

WO2018034164A1 - Vertical-type continuous casting method

Info

Publication number: WO2018034164A1
Application number: PCT/JP2017/028263
Authority: WO
Inventors: 佳文木村
Original assignee: 昭和電工株式会社
Priority date: 2016-08-18
Filing date: 2017-08-03
Publication date: 2018-02-22
Also published as: JP2018027559A; JP6785091B2

Abstract

The present invention provides a vertical-type continuous casting method whereby the peel depth due to peeling of an ingot is minimized and yield is enhanced, and it is possible to decrease the frequency of mold replacement and reduce cost. A vertical-type continuous casting method for performing continuous casting while supplying lubrication oil into a casting space from a top internal peripheral surface of a mold, using a vertical-type continuous casting device having a vertical-type continuous casting mold having a vertical cylindrical casting space and a pouring member provided with a pouring hole having an inside diameter smaller than the diameter of the casting space as a pouring hole for pouring molten metal into the casting space from above, wherein, in a stage prior to the start of continuous casting, the lubrication oil is supplied into the casting space from a mold internal surface, a variation in the supply rate of lubrication oil in a circumferential direction inside the casting space is measured, and the canter axis position of the pouring hole is offset relative to the center axis position of the casting space in accordance with the variation so as to be closer to a side where the supply rate of lubrication oil is greater, and continuous casting is subsequently performed.

Description

Vertical casting method

The present invention relates to a vertical continuous casting method such as a gas pressure hot top continuous casting method for various metals such as an aluminum alloy, and in particular, to obtain a continuous cast material with good surface quality while supplying lubricating oil. Is related to the technology.
It is about.
This application claims priority based on Japanese Patent Application No. 2016-160564 for which it applied to Japan on August 18, 2016, and uses the content here.

Conventionally, a continuous casting method is often used as a casting method for various metals such as aluminum and aluminum alloys. In the continuous casting method, in order to prevent seizure between the mold and the ingot surface, lubricating oil is generally supplied to the upper part (above the oil level) in the mold. Among various continuous casting methods, as a vertical continuous casting method mainly for non-ferrous metals, for example, as shown in Patent Document 1, a gas is blown on the molten metal surface in addition to lubricating oil, A gas pressure hot top continuous casting method has been developed, in which continuous casting is performed while being pressurized with gas, and has been put into practical use.

FIG. 1 shows an outline of a general example of a vertical continuous casting apparatus 1 for continuously casting a bar having a circular cross section by applying a gas-pressing hot top continuous casting method.
In FIG. 1, a vertical continuous casting apparatus 1 is generally for pouring a mold 3 having a hollow casting space 3 A having a vertical columnar shape and a molten metal 5 such as a molten aluminum alloy into the mold 3. The pouring member 7 is used.

The pouring member 7 is made of a refractory material for pouring the molten metal 5 introduced from a melting furnace or a molten metal holding furnace (not shown) into the mold 3, and is made of metal from the melting furnace or the molten metal holding furnace. A molten metal passage 7 B that guides the molten metal 5 to the mold 3 is provided, and a tip (lower end) thereof is a pouring port 7 A that opens vertically downward toward the upper end opening of the mold 3. The mold 3 is formed with a pressurizing gas passage 9, a lubricating oil passage 11, and a cooling water passage 13 in order from the top so as to surround the vertical cylindrical hollow casting space 3 A. A gas outlet 9A of the pressurizing gas passage 9 is opened at the upper end of the inner wall 3B of the mold 3 (vertical cylindrical inner wall defining the casting space 3A), and lubrication is provided below the gas outlet 9A. A lubricant discharge port 11A of the oil passage 11 is open. Further, a cooling water outlet 13A is formed in the lower part of the inner wall 3B of the mold 3 to discharge the cooling water guided from the cooling water passage 13 toward the ingot 15 in the casting space 3A.

Here, the pouring port 7A of the pouring member 7 is arranged so that the horizontal cross section is circular and the vertical center axis O1 coincides with the vertical center axis O2 of the casting space 3A of the mold 3. Is normal. The inner diameter _{D 1} of the pouring port 7A is smaller than the inner diameter D2 (diameter of the casting space 3A) _{D 2} of the mold 3. Therefore, the lower surface (lower end surface of the pouring member 7) of the peripheral portion of the pouring port 7A in the pouring member 7 protrudes inward (close to the central axis) from the inner peripheral position of the space at the upper end of the casting space 3A. become. In other words, when viewed from the casting space 3A side, the lower surface of the peripheral edge of the pouring port 7A overhangs in a bowl shape on the inner side in the horizontal direction at the upper end of the casting space 3A. Therefore, the portion of the peripheral edge of the pouring port 7A that protrudes to the inside of the casting space is hereinafter referred to as a flange portion 7B. The overhang distance (horizontal direction distance from the inner edge of the casting mold 3 to the inner edge of the pouring gate 7A: overhang amount) L is the total length of the casting space 3A in the general operation of the vertical hot top continuous casting. Usually, it is almost uniform in the circumference.

When continuously casting an aluminum alloy or the like by such a vertical continuous casting apparatus 1, the molten metal 5 is poured from above into the casting space 3 A of the mold 3 from the pouring gate 7 A of the pouring member 7. The mold 3 is cooled as a whole by the cooling water flowing through the cooling water passage 13, and the molten metal 5 starts to solidify from a position in contact with the inner surface of the mold, and is further cooled and solidified by the cooling water sprayed from the cooling water outlet 13A. Then, for example, a round bar-shaped ingot 15 is continuously drawn below the mold 3 to perform continuous casting.

During continuous casting, lubricating oil is supplied from the lubricating oil discharge port 11A to the upper end portion of the casting space 3A, and pressurized gas such as air is supplied from the gas outlet 9A. The molten oil and the pressurized gas are surrounded by the molten metal surface 5A of the unsolidified molten metal 5 in the mold, the upper inner wall surface 3B of the mold 3, and the flange 7B around the pouring port of the pouring member 7. A triangular corner space 17 is formed. The corner space 17 is sometimes referred to as a gas reservoir because it is pressurized. By supplying the lubricating oil as described above, seizure of the ingot surface against the inner surface of the mold is prevented. Furthermore, by performing gas pressurization together with the supply of lubricating oil, the contact area and contact friction between the initial solidification start site of the molten metal in the mold and the inner surface of the mold are reduced, and thereby smooth continuous casting (bar-shaped ingot 15 Smooth descent) and an ingot having a good surface property (cast surface) can be obtained.

Incidentally, irregularities called ripples often occur on the surface (cast surface) of the ingot obtained by continuous casting. FIG. 2 schematically shows the appearance of the round bar-shaped ingot 15 in which the ripple 19 is generated, and a longitudinal section in the vicinity of the ingot surface in which the ripple 19 is generated is schematically shown in an enlarged manner in FIG. Generally, the ripple 19 is generated in such a manner that a concave portion and a convex portion extend along the circumferential direction of the round bar-shaped ingot 15 and the concave and convex shape is periodically repeated in a wave shape in the casting direction.

Since a reverse segregation layer exists inside such a ripple, if the ingot with the ripple remaining is subjected to a subsequent process such as extrusion or forging, not only the surface properties deteriorate, but also surface defects occur. It becomes easy. The above-mentioned hot press casting using the gas pressurization method, although the degree of ripple is small compared to the normal continuous casting that does not perform gas pressurization and only supplies lubricating oil, it completely generates ripples. It is difficult to suppress this, and it is inevitable that a certain amount of ripple occurs. Therefore, the ingot after continuous casting is generally subjected to a post-process after removing a rippled ingot surface layer by peeling (peeling).

Japanese Patent No. 2707283

As described above, in gas-pressed vertical hot top continuous casting and other vertical continuous casting using lubricating oil, peeling is generally performed to remove ripples on the surface of the cast ingot. . In peeling, the skin peeling depth from the surface is determined in advance, and the surface layer is removed over the entire circumference of the bar-shaped ingot at the skin peeling depth.

By the way, in an actual continuous casting operation, the depth of the concave portion of the ripple usually varies greatly in the circumferential direction and the length direction of the bar-shaped ingot. Therefore, the peeling depth at the peak is set based on the deepest portion of the concave portion of the ripple so that the ripple is completely removed over the entire circumference and the entire length of the bar-shaped ingot. For example, in the example of FIG. 3, the depth of each recess 19 A due to the ripple 19 is large on the right side of FIG. 3 and small on the opposite side of 180 ° (left side of FIG. 3). Here, the recess depth of the portion with the largest recess depth on the right side of FIG. 3 is Pmax1, the recess depth of the portion with the greatest recess depth on the left side of FIG. 3 is Pmax2, and Pmax1 and Pmax2 Let the difference be P _q .
In this case, the peeling is based on the position where the depth of the concave portion on the right side of FIG. 3 is the largest (the portion where the concave portion depth is Pmax1), and the ripple and the resulting reverse segregation layer are completely removed at that location as well. the peeling depth P _0, then set slightly larger than Pmax1, in the peeling depth P _0, the entire circumference of the ingot 15, performs peeling over the entire length.

In this case, conversely, on the side where the recess depth in the ingot 15 is small (left side in FIG. 3), the ingot surface layer is wasted at a depth P ₀ that is much larger than the maximum recess depth Pmax2 on that side. It will be removed. That is, an extra portion corresponding to the difference P _q in the maximum recess depth is removed. Such a tendency becomes more prominent as the variation in the ripple depth in the circumferential direction increases.
This means that, in total, the amount of material removed by peeling is unnecessarily large, and the actual situation is that the product yield is adversely affected.

In addition, continuous casting with a mold is repeated many times, and when the variation in the recess depth of the ripple becomes remarkably large and the maximum value of the recess depth becomes remarkably large, the useful life of the mold is exhausted. For example, the casting mold of the continuous casting apparatus is generally replaced (updated) with a new one without being used thereafter. Therefore, the degree of variation in the recess depth of the ripple is one guideline for the mold renewal time in continuous casting. If the variation in the ripple depth becomes large at an early stage, the mold replacement frequency must be increased. Therefore, the actual situation is that the cost of continuous casting must be increased.

The present invention has been made against the background of the above circumstances, and it is possible to minimize the peeling depth by peeling to the ingot, thereby improving the yield, and moreover, the mold replacement frequency can be made higher than before. It is an object of the present invention to provide a vertical continuous casting method that can reduce the cost of continuous casting by reducing the cost.

In order to improve the yield by minimizing the peeling depth by peeling against the ingot, it was considered effective to reduce the variation in the circumferential direction of the recess depth of the ripple.
Then, when the cause of the variation in the depth of the concave portion of the ripple was examined, the variation in the circumferential direction of the supply amount of the lubricating oil supplied to the upper part of the casting space of the vertical continuous casting mold was the circumferential direction of the ripple concave portion. It was found to correlate with variation.

That is, as a tendency of variation in the amount of lubricating oil supplied in the circumferential direction, the direction in which the amount of lubricating oil is maximum and the direction in which the amount of lubricating oil is maximum in the horizontal plane is almost opposite to the direction of the center axis of the casting space (180 ° direction). On the other hand, as a tendency of the appearance of ripples in the bar-shaped ingot by vertical continuous casting, the recess depth is maximum in a certain direction in the horizontal plane with respect to the central axis position of the bar-shaped ingot, Tend to be minimal on the opposite side. In general, the larger the amount of lubricating oil supplied, the greater the effect of preventing seizure, but the more likely the ripple is generated (the unevenness of the ripple is increased).

Accordingly, the present inventors investigated the relationship between the variation in the circumferential direction of the mold circumferential direction of the lubrication oil supply amount and the variation in the circumferential direction of the recess depth of the ingot ripple. It has been found that the ripple recess depth is large on the side with a large amount of ripple, and the ripple recess depth is small on the side with a small amount of lubricating oil supply, or almost no ripple occurs.

From these results, it became clear that the circumferential variation in the depth of the concave portion of the ripple is mainly caused by the circumferential variation in the lubricating oil supplied to the upper part of the mold during continuous casting.
Here, variations in the circumferential direction of the lubricant supply amount are caused by errors in the dimensions of each part of the manufactured mold, thermal deformation of the mold over time, and the like. In practice, it is extremely difficult to eliminate the problem.

Therefore, a measure to avoid the variation in the circumferential direction of the lubricant supply amount from causing the variation in the depth of the concave portion of the ripple while allowing the lubricant supply amount to vary in the circumferential direction itself is considered. It was. In other words, instead of eliminating the circumferential variation of the lubricant supply amount itself, the variation in the circumferential direction of the lubricant amount does not affect the variation in the depth of the concave portion of the ripple while allowing the variation to exist. I thought about doing so.

Further, as a result of repeated examination by the inventors, the amount of lubricating oil supplied is adjusted by adjusting the position of the pouring port with respect to the casting space of the mold according to the variation in the circumferential direction of the amount of lubricating oil supplied into the casting space. It has been found that even if there is a variation in the circumferential direction, the variation in the circumferential direction of the ripple recess depth can be reduced.

That is, before the start of casting after pouring a molten metal into the casting space, the circumferential variation in the amount of lubricating oil supplied is measured, and the horizontal direction relative to the pouring port and the mold is determined according to the variation. By adjusting the position, specifically, by adjusting the horizontal relative position so that the pouring port is brought closer to the side where the lubricating oil supply amount is large, there is a variation in the lubricating oil supply amount. However, it has been found that the variation in the recess depth of the ripple can be reduced, and the present invention has been completed.

Therefore, the present invention provides each aspect described in the following (1) to (7).

(1) A vertical continuous casting mold having a vertical cylindrical casting space, and a pouring port for pouring molten metal from above into the casting space, the diameter of which is smaller than the diameter of the casting space In a vertical continuous casting method in which continuous casting is performed while supplying lubricating oil from the upper inner peripheral surface of the mold into the casting space, using a vertical continuous casting apparatus having a pouring member provided with a pouring spout,
Before the start of continuous casting by pouring molten metal into the casting space, lubricating oil is supplied into the casting space from the inner surface of the mold, and variation in the amount of lubricating oil supplied in the circumferential direction within the casting space is reduced. Measuring, and
Depending on the circumferential variation in the amount of lubricating oil supplied, the pouring member is placed on the casting space so that the center axis position of the pouring port is closer to the side where the lubricating oil supply amount is larger than the center axis position of the casting space. And relatively offset in the horizontal direction,
And then casting the molten metal into the casting space and performing continuous casting.

In the above (1), vertical continuous casting means continuous casting in which a continuous casting ingot is continuously drawn vertically downward from a mold. Further, offset means that the position is shifted.

(2) In the vertical continuous casting method of (1) above:
A vertical continuous casting method in which an offset amount of the center axis position of the pouring spout with respect to the center axis position of the casting space is determined in accordance with the circumferential variation of the lubricating oil supply amount measured before the start of casting.

(3) In the vertical continuous casting method of any one of (1) and (2),
In measuring the variation in the amount of lubricating oil supplied in the circumferential direction in the casting space, the casting space is divided into a plurality of regions at equal intervals in the circumferential direction, and the amount of lubricating oil flowing into each region within a predetermined time is determined. A vertical continuous casting method that measures the variation in the amount of lubricant supplied in the circumferential direction in the casting space by weighing and comparing the amount of lubricant flowing into each region.

(4) In the vertical continuous casting method of (3),
In measuring the variation in the amount of lubricating oil supplied in the casting space in the casting space, the lubricating oil has a bottomed vertical cylindrical shape with an open top and is divided into a plurality of regions in the circumferential direction by partition walls. A vertical continuous casting method in which a quantity variation measuring container is fitted into a mold and the amount of lubricating oil flowing into each region of the quantity variation lubricating container is measured within a predetermined time.

(5) In the vertical continuous casting method of any one of (1) to (4),
In continuous casting by pouring a molten metal into the mold, a pressurized gas is supplied together with lubricating oil from the upper inner peripheral surface of the mold into the casting space to perform gas pressurized hot top continuous casting. Mold continuous casting method.

(6) In the vertical continuous casting method of any one of (1) to (5),
A vertical continuous casting method in which the molten metal is a molten aluminum or aluminum alloy.

(7) In the vertical continuous casting method of any one of (1) to (6),
A vertical continuous casting method in which a vertical cylindrical mold is used as the mold and a round bar-shaped ingot having a circular cross section perpendicular to the axial direction is continuously cast.

According to the vertical continuous casting method of the present invention, it is possible to reduce the variation in the recess depth of the ripple in the ingot in the circumferential direction of the mold, so that the peeling depth at the peeling against the ingot is reduced and the yield is reduced. Improvement can be achieved, and the frequency of continuous casting can be reduced by reducing the frequency of mold replacement as compared with the prior art.

It is a longitudinal cross-sectional view which shows the outline | summary of the gas pressurization type vertical hot top continuous casting apparatus as an example of a vertical casting apparatus. It is a figure for demonstrating an example of the generation | occurrence | production state of the ripple in the conventional continuous casting ingot, and is a typical enlarged view of the cross section of a continuous casting ingot. It is a longitudinal cross-sectional view which expands and shows the part III in the ingot of FIG. It is a rough plan view showing an example of the lubricating oil amount variation measuring container used in the embodiment of the present invention. It is a longitudinal cross-sectional view which shows typically the state which incorporated the lubricating oil amount dispersion | variation measuring container shown by FIG. 4 in the continuous casting apparatus shown in FIG. It is a longitudinal cross-sectional view of the continuous casting apparatus according to FIG. 1 which shows an example of the state which adjusted the position of the pouring gate by applying the continuous casting method of this invention. It is a schematic diagram which shows the ratio of the lubricating oil amount of each area | region of the mold peripheral direction in an Example, and the condition of the offset of the pouring member based on it. It is a graph which shows the relationship between the amount of lubricating oil of each area | region of the casting_mold | template circumferential direction in an Example, and the recessed part depth ratio of the ripple in each ingot part corresponding to each area | region.

Hereinafter, embodiments of the vertical continuous casting method of the present invention will be described in detail. Note that the embodiments described below are merely examples, and the present invention is of course not limited to these embodiments. In addition, in the drawings used in the following description, in order to make the features easy to understand, the characteristic portions may be enlarged for convenience, or non-specific details may be omitted, and the dimensions of each component may be omitted. The ratio is not always the same as the actual one. In addition, the materials, dimensions, and the like exemplified in the following description are examples, and the present invention is not limited to them, and can be appropriately changed and implemented without changing the gist thereof.

Here, an example will be described in which a round bar-shaped ingot having a circular cross section is cast by applying to a gas pressure hot top continuous casting method in which a pressurized gas is supplied together with lubricating oil onto the oil surface in the mold. . As the continuous casting apparatus, it is assumed that the casting apparatus already described with reference to FIG. 1 is used, and the elements described with reference to FIG. 1 will be described using the same reference numerals as those in FIG.

In carrying out the continuous casting method of the present embodiment, in the stage before the casting is started into the mold, that is, before the molten metal is injected into the mold, the variation in the lubricant supply amount in the mold circumferential direction (in the horizontal plane) Measure the variation. That is, it is measured to which part (region) in the circumferential direction with respect to the central axis of the mold a large amount of lubricating oil is supplied and how much variation in the amount of lubricating oil is supplied.

As a specific method for measuring the circumferential variation in the amount of lubricating oil supplied, for example, a lubricating oil amount variation measuring container 21 as shown in FIG. 4 is fitted in the casting space 3A of the mold 3 as shown in FIG. And measure.

The lubricating oil amount variation measuring container 21 has a bottomed vertical cylindrical shape with an open upper surface that fits into the casting space 3A of the mold 3 as a whole (according to the shape of the casting space 3A in this embodiment). In the weighing container 21, a plurality of (for example, eight) partition walls 23 along the vertical direction and along the radial direction are equally spaced in the circumferential direction (examples of FIGS. 4 and 5). Is formed at intervals of 45 °. The spaces between the adjacent partition walls 23 are opened upward, and are divided areas Z1 to Z8 for receiving the lubricating oil flowing out from the lubricating oil blowing hole 11A into the casting space 3A.

Such a lubricating oil amount variation measuring container 21 is fitted into the mold 3 so that its upper end is located below the lubricating oil blowing hole 11A, and in this state, the lubricating oil supplied to the lubricating oil passage 11 in a steady operation state is supplied. Lubricating oil is supplied at an oil flow rate, and the lubricating oil is discharged into the mold 3 from the lubricating oil discharge hole 11A. Then, after the discharge of the lubricating oil is continued for a certain time (for example, 1 minute), the measuring container 21 is detached from the mold 3 and the amount of lubricating oil flowing into each of the regions Z1 to Z8 is measured. It is possible to measure the variation in the amount of lubricant supplied in That is, the direction of variation in the lubricant supply amount (maximum / minimum direction of the lubricant supply amount) and its degree (the difference between the maximum lubricant amount and the minimum lubricant amount among the lubricant amounts in each segment area) ).

Here, as described above, as the tendency of variation in the amount of lubricating oil in the circumferential direction of the mold, as described above, the portion where the lubricating oil amount is the largest and the smallest portion, and the opposite side with respect to the center position of the casting space Therefore, in each of the regions Z1 to Z8 in which the lubricating oil amount is measured as described above, the region where the lubricating oil amount is maximum (for example, the region Z6) and the minimum region (for example, the region Z2) are cast. Usually, the space is symmetrical with respect to the central axis O ₂ of the space 7A.

After measuring the variation in the circumferential direction of the lubricant supply amount as described above, the relative position adjustment of the pouring member 7 with respect to the mold 3 in the horizontal plane is performed according to the direction and degree of the variation. That is, in the normal continuous casting operation, as described with reference to FIG. 1, the vertical central axis O ₁ of the pouring port 7A of the pouring member 7 is the vertical central axis O ₂ of the casting space 3A of the mold 3. While setting the teeming member 7 so as to coincide with, in the present embodiment, for example, FIG. 6, as shown in FIG. 7, a pouring port center axis O ₁ of 7A is a vertical central axis of the casting space 3A The pouring member 7 is adjusted in position with respect to the mold 3 so as to be shifted (offset) by a predetermined distance L _{OFF in the} horizontal direction with respect to O ₂ . Here, the distance L _OFF is referred to as an offset amount. Here, the offset direction is the side where the amount of lubricating oil is large according to the direction of variation in the amount of lubricating oil supplied. That is, in the example of FIG. 6, assuming that the amount of lubricating oil on the left side of the drawing is large, the center axis O ₁ of the pouring port 7A is positioned on the left side with respect to the vertical center axis O _{2 of the} casting space 3A. , Offset.

Further, the offset amount L _OFF may be set according to the degree of variation in the lubricating oil supply amount. The specific offset amount L _OFF may be determined experimentally in accordance with the measured variation in the lubricant supply amount so that the variation in the lubricant supply amount is minimized. Here, the lubricating oil supply amount is in the maximum direction, the projection distances of the eaves portion 7B of the teeming member 7 (overhang) and L _p, in the lubricating oil supply amount is smallest direction, eaves teeming member 7 Assuming that the overhang distance (overhang amount) of the portion 7B is L _q , according to the experiments by the present inventors, when the number of area divisions is 8 (that is, when the area interval is 45 °), The ratio (L _p : L _q ) of the overhang distance (overhang amount) of the flange 7B of the pouring member 7 between the direction in which the lubricating oil supply amount is maximum and the minimum direction is approximately the amount of lubricating oil supply in the above direction. It has been found that by setting the offset amount L _OFF so as to be inversely proportional to the ratio, the variation in the lubricating oil supply amount can be suppressed to substantially zero.

For example, among the regions Z1 to Z8 divided into eight regions, the region with the largest lubricating oil supply amount is Zmax, the lubricating oil supply amount to the region Zmax is Qmax, the region with the smallest lubricating oil supply amount is Zmin, Let Qmin be the amount of lubricating oil supplied to the zone Zmin. For the overhang distance (overhang amount) L of the flange 7B, when the pouring port 7A is offset to the region Zmax side, the overhang amount on the region Zmax side is Lp, and the overhang amount on the region Zmin side is If Lq, the offset amount L _OFF is expressed by the following equation (1):
L _OFF = (L _q −L _p ) / 2 (1)
It is represented by Therefore, the overhang amounts L _p and L _q are _expressed by the following equation (2):
L _q : L _p = Qmax: Qmin (2)
By setting the offset amount L _OFF so that is satisfied, it has been found that the variation in the lubricant supply amount can be suppressed to substantially zero.

A specific method for adjusting the position of the pouring member 7 relative to the mold 3 is not particularly limited. For example, the pouring member 7 is attached to the mold 3 held at a fixed position. It is assumed that the support member is supported by a support member that can be adjusted in the X and Y directions in the horizontal plane, and the support member is moved in the X and / or Y direction according to the direction to be adjusted. That's fine. Alternatively, a connecting member such as a bolt for connecting the pouring member 7 and the mold 3 and its receiving part are provided with play so as to be movable in the X and Y directions in the horizontal plane in the non-fixed state. A structure may be used, and the pouring member 7 may be moved and adjusted in that state, and then connected and fixed.

As described above, the variation in the amount of lubricating oil supplied in the circumferential direction is measured, and the positional relationship between the pouring port 7A and the casting space 3A is adjusted according to the direction and magnitude of the variation (the central axis O ₁ of the pouring port is set). after offset) to the central axis O ₂ of the casting space, and pouring the molten metal into the casting space 3A from actually sprue 7A in this state, to start the continuous casting. The bar-shaped ingot 15 obtained in this way has little variation in the recess depth of the ripple in the circumferential direction. That is, on the side where the amount of lubricant supplied is large, the depth of the concave portion of the ripple is smaller than when the offset is not performed. On the other hand, on the side where the lubricating oil supply amount is small, the recess depth of the ripple tends to be larger than when not offset, but it is normal that the concave portion depth on the side where the lubricating oil supply amount is large is not exceeded. .

Therefore, by offsetting, the variation in the circumferential direction of the recess depth of the ripple can be reduced, and the maximum recess depth can be kept small. Therefore, also in peeling against an ingot, it is possible to reduce the skin peeling depth, minimize the amount of metal that is removed unnecessarily, and improve the product yield.

In addition, even if the mold is used for continuous casting without being offset, and the maximum recess depth of the ingot ripple is remarkably large, and it is conventionally determined that the useful life has been exhausted, If the offset is used in this way for continuous casting, the maximum recess depth of the ripple can be reduced, so that it can be used thereafter. That is, it is possible to extend the mold update time.

Here, the reason why the depth of the concave portion of the ripple can be reduced by moving the position of the pouring port 7A of the pouring member 7 to the side where the lubricating oil supply amount is large (offset) is not necessarily clear. but pouring port 7A the position of the center axis O ₁ of the center of the injection flow of molten metal from the pouring port 7A in other words, if it is offset relative to the position of the central axis O ₂ of the casting space 3A, in a mold The supply amount distribution of the supplied molten metal is not uniform in the horizontal plane, and a relatively large amount of the molten metal is supplied to the offset side. As a result, the metal flow velocity (lowering speed) at the contact surface when the molten metal comes into contact with the inner wall of the mold and initial solidification is started increases on the offset side. For this reason, even if the amount of the lubricating oil on the offset side is large, it is considered that ripples are less likely to occur or the depth of the concave portion of the ripples can be suppressed.

In the above-described embodiment, the casting space 3A is divided into eight regions at 45 ° intervals in the circumferential direction. However, the number of regions is not limited to eight, and the main points are divided into two or more regions. do it. However, in general, it is preferable to divide into even-numbered areas of 4 or more so as to be an axis target.

Further, the means for measuring the amount of lubricating oil in a plurality of divided areas in the casting space is not limited to the lubricating oil amount variation measuring container 21 as described above, and various means can be used.

Further, in the above-described embodiment, a round bar-shaped ingot having a circular face is continuously cast using a mold 3 having a cylindrical casting space 3A. However, the vertical continuous casting method of the present invention is used. Can also be applied to a case where a bar-shaped ingot having a square cross section is continuously cast using a mold having a rectangular cylindrical casting space.

The metal to which the vertical continuous casting method of the present invention can be applied is not particularly limited, and can be applied to all metals that can be continuously cast. For example, pure aluminum, various aluminum alloys, especially Al-- The present invention can be applied to Si-based (4000-based) eutectic alloys or hypereutectic alloys, 1000-7000 aluminum alloys, copper, copper alloys, and the like.

Furthermore, in the above-described embodiment, the gas pressurized vertical hot top continuous casting method has been described. However, the present invention is not limited to this, and can be applied to all vertical continuous casting methods in which casting is performed while supplying lubricating oil.

Examples of the present invention will be described below. The following examples are for clarifying the operation and effects of the present invention, and it is needless to say that the conditions described in the examples do not limit the technical scope of the present invention.

[Experimental Example 1]
FIG. 1 shows a hypereutectic Al—Si based alloy (mass%, Si: 14% Si, Cu: 4.5%, Mg: 0.55%, P: 0.01%, the balance being substantially Al). When continuous casting into a round bar-shaped ingot having a diameter of 64 mm was performed by the gas-pressurized vertical hot top continuous casting apparatus as shown in Fig. 1, the area was divided into 8 regions Z1 to Z8 by 45 ° before the start of casting. The lubricating oil variation measuring container 21 was set in the mold 3 as shown in FIG. The pouring port 7A has an inner diameter of 42 mm, and the casting mold 3 has an inner diameter (diameter of the casting space 3A) of 64 mm. Therefore, the center axis O ₁ of the pouring port 7A is aligned with the center axis O ₂ of the casting space (ie, not offset). The length (overhang amount) L of the flange portion 7B of the pouring member in the state) is 11 mm. Further, the lubricating oil variation measuring container 21 is a bottomed vertical cylindrical shape made of acrylic resin having an outer diameter of 64 mm and a height of 100 mm, and the thickness of the partition wall and the outer peripheral wall is 0.5 mm. In this state, the lubricating oil is supplied for 1 minute so that the total supply amount becomes 3.0 cc / min, and the lubricating oil accumulated in each region Z1 to Z8 of the measuring container 21 is sucked out by the dropper, and each region Z1 to Z8 is discharged. The amount of lubricating oil flowing into the tank was examined.

After the above measurement, the alloy was actually continuously cast at a casting speed of 280 mm / min. At the time of continuous casting, the lubricating oil is supplied so that the total supply amount is 3.0 cc / min as in the above measurement, and at the same time, air is used as a pressurized gas and air is introduced at a pressure of 0.1 MPa. While adjusting the valve appropriately, gas was pressurized.

The depth of the concave portion of the ripple on the surface of the obtained bar-shaped ingot was measured, and the variation in the circumferential direction of the depth of the ripple concave portion was examined. That is, the depth of the ripple concave portion is examined for each portion in the ingot circumferential direction corresponding to each of the regions Z1 to Z8, and the ratio (ripple concave portion depth ratio) Rd to the concave portion depth of the portion having the largest concave portion depth is determined. Asked.

Such an experiment is performed using a large number of molds having various different usage histories (mainly different number of times of use), and an example of a mold having the smallest variation in the depth of the concave portion of the ripple is shown in each of the regions Z1 to Z8. Table 1 shows the amount of lubricating oil and the ratio (ripple recess depth ratio) Rd of the ripple recess depth of each part of the ingot corresponding to each region to the recess depth of the part having the largest recess depth.
On the other hand, with respect to the example of the mold in which the variation in the depth of the concave portion of the ripple is the smallest, regarding the relationship between the lubricating oil amount and the ratio to the concave portion depth of the portion having the largest concave portion, the lubrication in each of the regions Z1 to Z8 Table 2 shows the amount of oil and the ratio (ripple recess depth ratio) Rd of the ripple recess depth of each part of the ingot corresponding to each region to the recess depth of the part having the largest recess depth.

As shown in Table 1, in the mold having a small variation in the lubricating oil amount in each of the regions Z1 to Z8, the variation in the ripple recess depth ratio Rd is small. On the other hand, as shown in Table 2, in the mold in which the variation in the lubricating oil amount in each of the regions Z1 to Z8 is large, the variation in the ripple recess depth ratio Rd is large, and the lubrication oil amount and the ripple recess depth ratio That the Rd magnitude is correlated, that is, the recess depth ratio Rd is the largest in the region Z6 where the amount of lubricating oil is the largest, and the ripple recess depth ratio Rd is the smallest in the region Z2 where the amount of lubricating oil is the smallest. It was confirmed. From these results, it is apparent that the variation in the circumferential direction of the lubricant supply amount affects the variation in the recess depth of the ripple.

[Example 2]
Further, for the example shown in Table 2 of Experimental Example 1 (an example in which the variation in the ripple recess depth ratio Rd was large), the pouring port of the pouring member was based on the measurement results in Table 2 before restarting continuous casting. The position adjustment (offset) of was performed as follows.

The amount of lubricating oil in each region Z1 ~ Z8 shown in Table 2, if indicated by the overall ratio lubricating oil supply amount to the (3.0cc / min) (the lubricating oil flow ratio) _{R q,} expressed as shown in FIG. 7 . In this example, the amount of lubricating oil in the region Z6 is the largest, from where the lubricating oil of the region Z2 opposite the least, the center position O ₁ of the pouring port 7A toward the side of the region Z6, internal angle region Z6 It was decided to adjust so as to be moved (offset) along the center line S.

State that has not been offset length of each direction of the eaves portion in (pouring port 7A center axis O ₁ state that coincides with the center axis O ₂ of the casting space 3A of) (overhang) L, the present embodiment Is 11 mm, and therefore, when offset is performed with the offset amount L _OFF , the overbar hang amount L _p (unit: mm) on the maximum lubricant amount side and the overbar hang amount L _q on the minimum lubricant amount side (unit: mm) mm) is L _p = 11−L _OFF (3)
L _q = 11 + L _OFF (4)
It is represented by Also as shown in FIG. 7, the lubricating oil amount ratio R _q of the lubricating oil up to the region Z6 0.16, the amount of lubricating oil ratio R _q of the lubricating oil smallest area Z2 a 0.09, these When the value of the lubricating oil amount ratio is converted into the lubricating oil amount in each region by the total lubricating oil supply amount (3.0 cc / min), the lubricating oil amount Qmax in the maximum lubricating oil region Z6 is 0.48 cc / min. The lubricating oil amount Qmin in the minimum lubricating oil region Z2 is 0.27 cc / min. Therefore, if the numerical values of these lubricating oil amounts Qmax and Qmin are substituted,
(11 + L _OFF ) :( 11−L _OFF ) = 0.48: 0.27 (5)
It becomes. From this equation (5)
L _OFF = 3.08mm (6)
The value of is obtained.
Therefore, the center axis O ₁ of the pouring port 7A is offset by L _OFF = 3.08 mm along the center line S of the inner angle of the region Z6 on the side of the region Z6 with respect to the center axis O ₂ of the casting space 3A. In addition, the position of the pouring member 7 was moved and adjusted. The position of the central axis of the pouring port 7A after movement adjustment is denoted by reference symbol O ₁ '.

After offsetting in this way, continuous casting was performed again under the same conditions as in Experimental Example 1.
The depth of the concave portion of the ripple on the surface of the obtained bar-shaped ingot was measured, and the variation in the circumferential direction of the depth of the ripple concave portion was examined. That is, the depth of the ripple concave portion is examined for each portion in the ingot circumferential direction corresponding to each of the regions Z1 to Z8, and the ratio of the concave portion depth of each portion to the concave portion depth in the portion having the largest concave portion depth (ripple The recess depth ratio Rd) was calculated. The value is indicated by a one-dot chain line in FIG. 8 as “ripple concave depth ratio Rd−1 after offset”.

Note that the ripple recess depth ratio Rd of each part in the case of continuous casting without being offset is indicated by a broken line in FIG. 8 as “ripple recess depth ratio Rd-2 before offset”.
Further, the amount of lubricating oil in each of the regions Z1 to Z8 is indicated by a solid line in FIG.

As apparent from FIG. 8, in the continuous casting of a state that has not been offset, in correlation with the large variation in the amount of lubricating oil, but the variation of the ripple recess depth was large, the pouring port of the L _{OFF = 3.} By continuously casting in a state offset by 08 mm toward the region Z6, variation in the ripple recess depth could be remarkably reduced.

Therefore, by offsetting the pouring spout as described above, it becomes possible to reduce the peeling depth in peeling against the ingot, and as a result, the amount of material removed by peeling is reduced and the product yield is increased. It becomes possible.

Also, as the variation in the circumferential direction of the concave portion of the ripple becomes smaller, the time until the maximum value of the concave portion of the ripple is judged to require mold renewal is delayed, and as a result, the frequency of mold replacement is also reduced. Therefore, the cost increase of continuous casting can be suppressed.

3 ... mold, 3A ... casting space, 7 ... teeming member, 7A ... sprue, 11A ... lubricant discharging port, 15 ... ingot, 21 ... lubricating oil amount variation measuring container, O 1 _... sprue central axis, O ₂ ... Center axis of casting space, L _OFF ... Offset amount.

Claims

A vertical continuous casting mold having a vertical cylindrical casting space, and a pouring port for pouring molten metal from above into the casting space, the pouring port having a diameter smaller than the diameter of the casting space In a vertical continuous casting method in which continuous casting is performed while supplying lubricating oil into the casting space from the upper inner peripheral surface of the mold using a vertical continuous casting apparatus having a pouring member provided,
Before the start of continuous casting by pouring molten metal into the casting space, lubricating oil is supplied into the casting space from the inner surface of the mold, and variation in the amount of lubricating oil supplied in the circumferential direction within the casting space is reduced. Measuring, and
Relative to the circumferential direction variation of the lubricating oil supply amount, the center axis position of the pouring port is relative to the casting space so as to be closer to the side where the lubricating oil supply amount is larger than the central axis position of the casting space. The step of automatically offsetting,
And then casting the molten metal into the casting space and performing continuous casting.
2. The vertical continuous type according to claim 1, wherein an offset amount of the center axis position of the pouring port with respect to the center axis position of the casting space is determined according to a size of a circumferential variation in a lubricant supply amount measured before the start of casting. Casting method.
To measure the variation in the amount of lubricating oil supplied in the circumferential direction in the casting space, the casting space is divided into multiple regions at equal intervals in the circumferential direction, and the amount of lubricating oil flowing into each region within a predetermined time is measured. Then, the variation of the lubricating oil supply amount in the circumferential direction in the casting space is measured by comparing the lubricating oil inflow amount into each region, and the vertical continuation according to any one of claims 1 and 2 Casting method.
In measuring the variation in the amount of lubricating oil supplied in the casting space in the casting space, the amount of lubricating oil having a bottomed vertical cylinder with an open top and divided into a plurality of regions in the circumferential direction by partition walls 4. The vertical continuous casting method according to claim 3, wherein the variation measuring container is fitted into a mold and the amount of lubricating oil flowing into each region of the lubricating oil amount variation measuring container within a predetermined time is measured.
In continuous casting by pouring a molten metal into the mold, a pressurized gas is supplied from the upper inner peripheral surface of the mold into the casting space together with lubricating oil to perform gas pressurized hot top continuous casting. The vertical continuous casting method according to any one of claims 1 to 4.
The vertical continuous casting method according to any one of claims 1 to 5, wherein the molten metal is a molten aluminum or aluminum alloy.
The vertical continuous casting method according to any one of claims 1 to 6, wherein a vertical cylindrical shape is used as the mold, and a round bar-shaped ingot having a circular cross section perpendicular to the axial direction is continuously cast. .