JPS5949103B2 - Continuous metal casting method - Google Patents

Description

[Detailed description of the invention] The present invention relates to a continuous metal casting method.

More specifically, the present invention relates to an improvement in the so-called hot-top casting process, ie, a process for continuous casting of metals using articulated insulated refractory baths and forced cooling molds.

Billets (for extrusion) are materials for drawing metals, such as aluminum and aluminum alloys.

Slabs (for rolling), wire bars (for rolling and drawing), etc. are generally manufactured by continuous casting, particularly by vertical semi-continuous water-cooled casting (so-called vertical continuous casting).

In this case, in order to increase productivity, it is common to use a large number of molds to obtain a large number of ingots at the same time, so-called multiple casting.

Particularly in this case, control of the molten metal level in each mold is directly related to product quality and casting yield and is important, but this depends in large part on equipment management and operator skill.

Conventionally, a float method as shown in FIG. 1 has generally been adopted for the above-mentioned level control.

In Figure 1, 1 is a casting furnace, 2 is a launder (molten metal trough)
, 3 is a distribution board, 4 is a molten metal supply pipe, 5 is a float (floating type molten metal valve), and 6 is a forced cooling mold.

The mold 6 is cooled by cooling water that is introduced from the cooling lower and jetted inward from the cooling water spout 8.

The molten metal 9 is supplied from the casting furnace 1 through the long tube 2 to the distribution board 3, from there it is introduced into the mold 6 through the pipe 4, and moves downward while forming the columnar body 10.

The upper part 11 of the columnar body 10 remains molten metal, but the lower part is sequentially cooled and solidified by the inner wall of the mold 6 and the jetted cooling water, and an ingot 12 is produced.

The level control of the molten metal 11 in the mold 6, that is, the control of the supply rate of the molten metal from the pipe 4, is performed by the float 5 which floats on the surface of the molten metal and acts as a valve. It is difficult to save labor because it requires manpower to attach and detach the float, repair it, and manage operations during casting.

In addition, from the perspective of ingot quality, generally speaking, the lower the molten metal surface in the mold is, the smoother the casting surface will be, and the better the surface quality will be.However, if the molten metal surface, that is, the operating level of the float, is too low, the float This results in poor properties and problems in stable casting.

Furthermore, since a float is used, there is a great risk that foreign substances such as oxides will be caught in the ingot.

On the other hand, hot-top casting is a new technology that is expected to save labor and improve ingot quality and casting yield in semi-continuous casting, and has been researched and developed at home and abroad for about 15 years. It continued.

In the hot top casting method, a molten metal receiving tank (header box) made of an insulating refractory material is installed on top of a shallow mold (short mold) that has the length necessary for solidification, and the launder is removed from the casting furnace. The molten metal is fed from the distribution panel to each header at a horizontal level without any steps, and solidification progresses.

Therefore, in this method, the casting speed can be increased due to the short mold, and the lack of use of floats results in labor savings and improved ingot quality.

FIG. 2 generally illustrates the hot top casting process.

In Fig. 2, 21 is a casting furnace, 22 is a launder, 23
2 is a molten metal receiving tank, and 24 is a forced cooling mold.

The cooling water that cools the mold 24 from inside is jetted inward from the cooling water spout 25.

The molten metal 26 is supplied from the casting furnace 21 to the molten metal receiving tank 23 via the launder 22.

Although a distribution board is not shown in Fig. 2, in the case of multiple casting, the launder itself may be configured to branch out and supply molten metal directly to multiple molten metal receiving tanks, or the launder A unique distribution board may be provided at the tip of the molten metal receiving tank to supply molten metal to a plurality of molten metal receiving tanks.

The molten metal supplied into the receiving tank 23 forms a reservoir 27 therein and forms columnar bodies 28 while moving downward.

The upper part of the columnar body 28 continues to remain molten metal in the reservoir in the receiving tank 23, but the lower part is sequentially cooled and solidified by the cooling water jetted from the inner wall of the mold 24 and the cooling water spout 25, and an ingot 29 is formed. generate.

The first person to invent the hot top casting method was T.
He proposed the Isomet Process as a crack-free casting method, and added a device similar to the hot-top casting method (Journa).
l of The In5titude of Meta
ls.

92.305 (1963)).

Since then, various technologies related to hot top casting methods have been proposed both domestically and internationally (for example, U.S. Patent No. 2983
No. 972, No. 3212142, British Patent No. 1389
No. 784, Special Publication No. 48-44607, Special Publication No. 49-2
No. 3740, JP-A-50-79429, JP-A-51-
148620, etc.).

However, these conventional methods have not fully solved problems such as seizure phenomenon, wavy casting surface (ripple), or sweating casting surface, and have the disadvantage that the appearance of the ingot is poor compared to the float method. There is.

A technique called the gas pressurization method has recently attracted attention as a hot-top casting technique (for example, Japanese Patent Application Laid-Open No. 53-1
5222, etc.).

The gas pressurization method is a method in which gas at a pressure close to the hydrostatic pressure of the molten metal is introduced directly below the molten metal receiving tank, entraining lubricating oil in the oil sump and supplying it to the inner wall of the mold, Compared to conventional hot-top casting, the joining point of the mold, molten metal, and lubricant moves downward, reducing the effective mold length.
It has the characteristic that a good ingot surface can be obtained.

However, in order to perform stable casting in the gas pressurization method, it is necessary to minimize fluctuations in the molten metal level in the molten metal receiving tank, and it is also necessary to supply gas uniformly into the mold, so it is especially necessary to perform multiple casting. This is considered to be accompanied by difficulties in terms of equipment and operation.

The following may be considered to be the cause of the deterioration of the appearance of the ingot in the conventional hot top casting method as described above.

(a) The casting speed is faster than in the float method, and the contact friction between the molten metal and the mold is increased due to the feeding effect of the molten metal in the receiving tank, making uniform supply of lubricating oil even more important. However, due to the structure of casting equipment, it is difficult to supply lubricating oil uniformly.

(b) In the combination of the molten metal receiving tank and the mold, if the lower end surface of the inner periphery of the molten metal receiving tank extends inward from the extension of the inner peripheral surface of the mold to form an overhang part, due to its structure. The molten metal tends to accumulate directly under the overhang, and the molten metal tends to enter the lubricating oil supply groove and solidify in this area.

The inventors of the present invention focused on the structure of the mold, the shape of the molten metal receiving tank, and the lubricant supply method based on the consideration of the drawbacks of these conventional techniques and their causes, and as a result of repeated studies,
The present invention was achieved by discovering that a good ingot can be obtained by a specific combination thereof.

That is, an object of the present invention is to provide hot-top casting with good workability and good ingot quality. It is composed of a forced cooling mold which is coaxially arranged and whose inner wall forms a substantially vertical surface and whose upper and lower ends are open, and a coolant jetting means for jetting the coolant inwardly under the mold. Using a vertical continuous casting device, the molten metal is fed into the receiving tank to form a pool therein, and is moved downward while forming a columnar body, and the columnar body is sequentially applied to the inner wall of the mold and the above-mentioned mold. In a method that includes generating a columnar ingot by cooling it by contacting with a coolant, at least the vicinity of the lower end of the receiving tank is stretched such that the inner wall thereof is located inside the extension surface of the inner wall of the mold. The lower end of the projecting part protrudes downward to cover the upper part of the inner wall of the mold to form a short cylindrical hanging part, and the inner peripheral surface of the hanging part extends downward. The outer circumferential surface forms a narrow gap with the inner wall of the mold, and the upper part of the inner wall of the mold covered with the hanging part forms a slope. Abstract: A method for continuous metal casting, characterized in that a lubricant supply port is open, and lubricant is forcibly supplied from there, passing through the gap and covering the entire circumference of the inner wall of the mold. That is.

Hereinafter, the present invention will be explained in more detail with reference to the drawings showing examples of embodiments of the present invention.

FIG. 3 is a vertical sectional view schematically showing an example of a vertical continuous casting apparatus used in the method of the present invention and a state in which continuous casting is performed using the same.

In Fig. 3, 31 is a launder or distribution board, 32 is a molten metal receiving tank made of an insulated refractory, 33 is a forced cooling mold, 34 is a coolant inlet, and 35 is for spouting the coolant that has passed through the mold inward. This is the coolant outlet.

Typically, water is used as the coolant.

The mold 33 is made of a thermally conductive material such as metal (for example aluminum) or graphite, and its inner wall 36 forms a substantially vertical surface with open top and bottom ends.

Since the cross-sectional shape of the inner wall defines the desired cross-sectional shape of the ingot, it is circular when obtaining a cylindrical ingot, and a corresponding polygon when obtaining a prismatic ingot. shall be.

In these cases, a hollow ingot can be obtained by installing a suitable core further inside the inner wall of the mold.

The vicinity of the upper end of the inner wall of the mold 33 protrudes over the entire circumference to form a protrusion 37 .

A lubricant supply port is opened at the lower end surface 38 of the protrusion 37, and lubricant is forcibly supplied from the port by a pump, a fluid pressure device, etc., so as to cover the entire circumference of the mold inner wall 36.

The arrangement of the lubricant supply ports is not particularly limited, and they may be opened continuously (i.e., in an annular shape) over the entire circumference of the mold inner wall, or discontinuously (with many small holes) over the entire circumference. You may do so.

However, in the latter case, it is desirable that the intervals between the discrete supply ports are not too large so that the supplied lubricant covers the entire circumference of the inner wall of the mold as uniformly as possible.

Note that the mold does not necessarily have a protruding portion near the upper end of the inner wall, and the lubricant supply port may also be opened not in the lower end surface of the protruding portion but in the vertical surface of the upper portion of the inner wall of the mold.

However, as will be described later, it is preferable to have the above protrusion in order to align the molten metal receiving tank and the mold, and if there is a protrusion, it is better to open the lubricant supply port on the lower end surface of the protrusion. This is preferable because uniform supply to the inner wall surface of the mold can be carried out more easily.

The molten metal receiving tank 32 is made of an insulating refractory material such as asbestos fiber, diatomaceous earth, or quartz (known by trade names such as Marinite and Masrock).
The mold 33 is manufactured by the mold 33, and is installed in a continuous manner on top of the mold 33.

The structure of the upper part of the molten metal receiving tank is not particularly limited other than having an inlet for receiving the molten metal supplied from the launder or distribution board, and may have a structure in which multiple receiving tanks are fused to form one distribution board. You can do something.

However, the molten metal receiving tank must be open at its lower end and positioned such that at least its lower portion is in coaxial relationship with the mold.

In FIG. 3, the lower inner wall 39 of the receiving tank 32 is arranged coaxially with the inner wall 36 of the mold 33.

Further, in this coaxial relationship, the lower inner wall 39 of the receiver is located inside the (extended surface of) the inner wall 36 of the mold.

That is, the vicinity of the lower end of the receiving tank 32 forms an overhang above the mold 33.

Now, one of the structural features of the molten metal receiving tank 32 used in the method of the present invention resides in its hanging portion 40.

The hanging part 40 has a cylindrical shape that protrudes downward in a short manner so that the lower end of the projecting part covers the upper part of the inner wall 36 of the mold.

Therefore, the inner circumferential surface 41 of the hanging portion 40 forms an inclined surface that gradually expands downward, and the hanging portion 40
The outer peripheral surface 42 of the mold 33 has a narrow gap between the inner wall 36 of the mold 33.

Since there is such a narrow gap between the hanging portion 40 and the mold 33, it is not always easy to arrange them coaxially, that is, to align the receiving tank 32 and the mold 33.

However, since the protruding part 37 is provided near the upper end of the inner wall of the mold 33 so as to partially fill the gap, the above-mentioned problem can be easily achieved by fitting the hanging part 40 with the inner periphery of the protruding part 31. Alignment is performed.

Further, one of the features of the casting apparatus used in the method of the present invention is that a lubricant supply port is opened in the upper part of the inner wall of the mold covered with the hanging part, that is, in the upper part of the inner wall of the mold located in the gap. It consists in being.

In the mold shown in FIG. 3, the lubricant supply port is located at the protrusion 37.
Although the lubricant supply port is opened at the lower end surface 38 of the lubricant supply port, the position of the lubricant supply port is not limited thereto, as described above.

The lubricant is guided to the lubricant supply port by a forced supply mechanism (not shown) such as a pump or a hydraulic device, and is pushed out from there into the mold, passing through the gap and spreading around the entire circumference of the inner wall 36 of the mold. Lubricate the inner wall of the mold.

The form of ingot production in the continuous casting method of the present invention is not particularly different from that in the conventional hot top casting method described above with reference to FIG.

Molten metal 43 is supplied from a casting furnace (not shown) through a launder or distribution plate 31 into the molten metal receiving tank 32, forms a molten metal reservoir 44 therein, and moves downward while forming columnar bodies 45.

The upper part of the columnar body 45 continues to remain molten metal in the reservoir 44 in the receiving tank 32, but the lower part is sequentially cooled and solidified by the coolant jetted from the inner wall 36 of the mold and the coolant spout 35, and becomes an ingot 46. is generated.

4 to 6 show a preferred example of a combination of the molten metal receiving tank 32 and the forced cooling mold 33 of the type shown in FIG. 3, with particular emphasis on the lubricant supply path.

FIG. 4 is a longitudinal cross-sectional view similar to FIG.
-42 are the same as in FIG.

Reference numeral 51 denotes a heat insulating part for insulating the upper inner wall of the mold 33 on the back side of the hanging part 40, and is hollow or made of a suitable heat insulating material.

Reference numeral 52 denotes a lubricant inlet, which is provided at one or more locations on the outer periphery of the mold 33.

Reference numeral 53 denotes a lubricant reservoir, which is provided inside the mold 33 over the entire circumference (in an annular shape).

54 is a lubricant flow path.

The protruding portion 37 is provided with vertical narrow grooves that serve as lubricant flow paths at short intervals over the entire circumference.

FIG. 5 is a partial cross-sectional view of the mold 33 shown in FIG. 4, taken along line A-A', where the lubricant supply path is located.

6 is a perspective view showing the shape of the inner wall of the mold 33 shown in FIG. 4 near the upper end thereof.

In FIGS. 5 and 6, 55 is the above-mentioned vertically oriented narrow groove.

4-6, lubricant is introduced into lubricant reservoir 52 by a force-feeding mechanism (not shown) and lubricant reservoir 53.
from which the lubricant channel 54 and the vertical narrow groove 5 are filled.
5, it is pushed out from the lubricant supply port at its lower end into the gap on the back side of the hanging part 40, and then spreads around the entire circumference of the inner wall 36 of the mold to lubricate it.

Like this in the lubricant supply route? By providing a lubricant reservoir and a lubricant reservoir, the amount of lubricant supplied to the entire circumference of the inner wall of the mold can be made more uniform.

In the present invention, a molten metal receiving tank having a cylindrical hanging portion having an inclined inner circumferential surface is used, which achieves the following effects.

(2) Since the lubricant supply port is covered by the hanging portion, molten metal is prevented from entering the supply port.

■ The hanging part covers the upper inner wall of the mold, which has poor cooling efficiency, and prevents solidification in this area, improving the appearance of the ingot.

■ The sloping inner surface of the hanging part allows the molten metal to flow smoothly and solidify steadily.
The appearance of the ingot is improved.

If the inner circumferential surface is not a sloped surface, the molten metal tends to accumulate directly under the hanging portion, and solidification in this portion results in poor appearance of the ingot.

■ Since the molten metal receiving tank is fitted onto the mold, it is easy to replace.

Therefore, the quality of the ingot can be optimized by appropriately changing the length of the hanging portion depending on the molten metal composition and the size of the ingot.

In this case, the length of the hanging portion is preferably selected based on the effective mold length.

The effective mold length is defined as the distance from the lower end surface of the hanging portion of the molten metal receiver to the location where the coolant hits the ingot.

Generally, good results can be obtained by increasing the effective mold length as the amount of alloy components in the alloy composition increases and the size of the ingot increases.

The preferred angle of inclination of the inner peripheral surface of the hanging part depends on the composition of the molten metal, the size of the ingot, etc., and its optimum value should be determined experimentally. angle is 80
'Good results can be obtained by setting the angle more preferably in the range of 50 to 70 degrees.

Furthermore, in the hot top casting method, which uses a casting device in which the lower end of the inner circumferential surface of the molten metal receiving tank extends further inward than the inner wall of the mold, it is known that the width of the extension affects the quality of the ingot. .

For example, in the method disclosed in Japanese Patent Publication No. 49-23740, it is stated that wavy casting surface (Ritz) is prevented by suppressing the overhang width to 3.1 mm or less and adjusting the casting speed. ing.

However, in the casting apparatus used in the present invention, the flow of the molten metal is smoothed by the sloped surface on the inner periphery of the hanging part, so the restrictions on the overhang width are more relaxed, and an appropriate casting speed can be selected. In this case, an ingot without a wavy casting surface can be obtained even when the protruding width at the lower end of the hanging portion is large, for example, 5 mm.

Next, the lubricant supply conditions in the method of the present invention will be explained.

Generally, in the hot top casting method, unlike the float method, the upper end of the mold is closed by molten metal, and therefore it is known that the lubricant supply method needs to be devised.

Inventive method? In this case, a method is adopted in which the lubricant is forcibly and automatically supplied from the outside, but the following points should be kept in mind in this case.

■ The lubricant should be supplied as evenly as possible to the inner wall surface of the mold.

■ The lubricant supply port and molten metal should not come into contact.

■ Since the lubricant flows through narrow passages with high resistance, it needs to have a somewhat low viscosity, but from the perspective of lubricating ability, it is better to have a high viscosity, so there must be an appropriate viscosity range.

■ If the amount of lubricant supplied is too low, seizure will occur, and if it is too much, the cooling ability of the mold will be impaired and a sweating casting surface will occur, so there must be an appropriate range of supply amount.

■ No residue is generated due to the reaction between the lubricant and the molten metal.

These points depend on the molten metal composition, casting speed, and other casting conditions, and therefore, the optimal lubricant supply conditions should be determined experimentally for each specific casting object.

However, within the scope of the studies conducted by the present inventors regarding the casting of ordinary aluminum or aluminum alloy by the method of the present invention, it has been found that the following conditions are suitable.

As a lubricant, for example, a viscosity of 1 to 3000 cP (20°C
), various lubricating oils can be used, such as mineral oil, animal and vegetable oils (castor oil, rapeseed oil, turpentine oil), silicone oil, and graphite powder-animal oil slurry (trade name Rubix). Castor oil is the best choice.

A suitable feed rate of the lubricant is 6 x 10'' to 1.8 x 10-'' cc/ expressed in feed amount per unit surface area of the ingot.
The range is crit.

[This means that when a billet with a diameter of 2547/lr/l is cast at a casting speed of 95 mm1-, 0.5 to 1.4 CC/l is cast.
Corresponds to the supply rate of ynMr.

] The arrangement of the lubricant supply port in the gap on the side of the hanging part of the molten metal receiving tank can take various arrangements as described above as long as the lubricant can be uniformly supplied onto the inner wall of the mold. Particularly advantageous is a system in which a vertical narrow groove is provided in the protruding part of the mold, and the lower end of the groove is used as a lubricant supply port, as shown in FIGS.

In this case, the protrusion width of the protrusion 37 is 27n11t or less, more preferably 0.5m or less, and the installation interval (pitch) of the vertical grooves 55 is 20m or less, more preferably 10m.
It is desirable that it be less than m.

In this case, since the vertically oriented narrow grooves 55 are covered by the hanging portions 40, molten metal will not enter the narrow grooves.

Even if the mold does not have the above-mentioned protruding parts, in order to supply lubricant sufficiently uniformly to the contact points between the inner wall of the mold and the molten metal without the molten metal entering the lubricant supply port, it is necessary to The width of the gap between the mold and the inner wall of the mold is desirably 2u or less, more preferably 0.5 myrtJJ or less.

As previously mentioned, the effect of using a molten metal receiving tank with a hanging part is that the appearance of the ingot is improved by preventing solidification near the upper end of the mold, but even in this case, the hanging part structure and casting Depending on the combination of conditions, lubricant supply conditions, etc., there is a risk that heat extraction, ie, cooling, will occur through the path between the inner wall of the mold and the lower part of the lubricant, and solidification will begin in the hanging part.

This corresponds to substantially increasing the effective mold length, and the skin quality of the ingot deteriorates.

One way to improve this situation is to provide a heat insulator in the upper part of the mold located on the back side of the hanging part to alleviate the cooling from the mold.

This is the heat insulating part 51 previously explained in connection with FIGS. 4 and 5. In this case, the temperature of the hanging part increases compared to the case without the heat insulating part, and the wavy casting surface (ripples) is caused. The shape is improved and the epidermal segregation layer is also improved.

Next, specific embodiments of the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to the following Examples unless the gist thereof is exceeded.

Example 1 Casting equipment of the type shown in Figures 4 to 6 (without heat insulation part)
was used to cast billets of various aluminum and aluminum alloys.

The length of the hanging part of the molten metal receiving tank is changed according to the molten metal composition and the ingot diameter, and the optimum values of the actual mold length (-mold length one hand length) and casting speed are determined to obtain an ingot with a smooth surface. selected.

The values obtained and the quality of the ingots obtained under the conditions are shown in Table 1.

In addition, in the above-mentioned casting apparatus, the inclination angle of the inner circumferential surface of the hanging part of the molten metal receiving tank (with respect to the horizontal plane) is 60 degrees, the overhang width of the lower end of the hanging part is 5 mm, and the width of the gap between the outer periphery of the hanging part and the inner wall of the mold is It was 0.5 mm.

Also, castor oil is used as a lubricant, and the supply amount is 1. Ox 10-3 cc/i.

Example 2 Billets of aluminum 6063 alloy were cast using casting equipment of the type shown in Figures 4 to 6 (with and without heat insulation).

Billet diameter is 177 dragons, casting speed is 135 mm/mi
n, the actual mold length was 251ftlt.

In the above casting apparatus, the angle of inclination of the inner circumferential surface of the hanging part of the molten metal receiving tank (with respect to the horizontal plane) is 60°, the overhang width of the lower end of the hanging part is 5 degrees, and the width of the gap between the outer layer of the hanging part and the inner wall of the mold is 0. .5
It was mm.

Also, castor oil is used as a lubricant, and the supply amount is as follows:
Based on the ingot surface area: 1. OX 10-3cc/cy
It was tt.

Comparing those with and without insulation, the temperature of the drooping part increased by 40 to 70°C in the case with insulation, and as shown in Table 2, improvements in ripple shape and skin segregation layer were observed. Ta.

[Brief explanation of the drawing]

FIG. 1 is a vertical sectional view schematically showing a float method casting apparatus and a casting state. FIG. 2 is a vertical sectional view schematically showing a casting apparatus and casting state of a general hot top casting method. FIG. 3 is a vertical cross-sectional view schematically showing an example of a casting apparatus and a casting state in the hot-top casting method according to the present invention. 4 to 6 are schematic diagrams showing a preferred example of a casting apparatus used in the method of the present invention, in which FIG. 4 is a partial vertical sectional view showing a combination of a molten metal receiving tank and a forced cooling mold, and FIG. 5 is a mold FIG. 6 is a partial perspective view showing the shape of the upper end of the inner wall of the mold. 1: Casting furnace, 2: Launder, 3: Distribution board, 5: Float, 6: Mold, 9: Molten metal, 12: Ingot, 21: Casting furnace, 2
2: launder, 23: molten metal receiving tank, 24: mold, 25: cooling water spout, 26: molten metal, 27: molten metal reservoir, 29: ingot,
32: Molten metal receiving tank, 33: Mold, 35: Coolant spout, 3
7: Projection part, 40: Drooping part, 43: Molten metal, 44: Molten metal reservoir, 46: Ingot, 51: Heat insulation part, 53: Lubricant reservoir, 54:
Lubricant channel, 55: narrow groove.

Claims (1)

[Scope of Claims] 1. A molten metal receiving tank made of an insulating refractory with an open bottom end, and a molten metal receiving tank made of a heat insulating refractory material, which is disposed coaxially with the bottom of the receiving tank and has an inner wall substantially forming a vertical surface, and has an open top and bottom end. A vertical continuous casting device is used, which is composed of a forced cooling mold, and a coolant jetting means for spouting coolant inward under the mold, and the molten metal is supplied into the receiving tank. A method that includes forming a columnar ingot while forming a reservoir and moving the columnar body downward, and sequentially bringing the columnar body into contact with the inner wall of the mold and the coolant to cool it, thereby producing a columnar ingot. At least near the lower end of the receiving tank is formed with an overhang such that the inner wall thereof is located inside the extension surface of the inner wall of the mold, and the lower end of the overhang is above the inner wall of the mold. A short cylindrical hanging part is formed by protruding downward so as to cover the mold. A lubricant supply port is formed in the upper part of the inner wall of the mold, which is covered with the hanging part, and the lubricant is forcibly supplied from there. A method for continuous metal casting, characterized in that the entire inner wall of the mold is covered through the gap. 2. The method for continuous metal casting according to claim 1, characterized in that the lubricant supply port consists of a large number of horizontal small holes provided at short intervals around the entire upper circumference of the inner wall of the mold. How to do it. 3. In the method for continuous casting of metal according to claim 1, the inner wall of the mold protrudes near the upper end so as to fill the gap between the outer circumferential surface of the hanging portion of the receiving tank and the inner wall of the mold. A circumferential protruding portion is formed, and the protruding portion is provided with a large number of vertically oriented narrow grooves that serve as lubricant passages at short intervals, and the lower end of the narrow groove serves as the lubricant supply port. A method characterized by: 4% allowance In the method for continuous metal casting according to any one of claims 1 to 3, the lubricant is supplied from the forced supply mechanism to the lubricant supply port through the lubricant reservoir in the mold. A method characterized by being guided. 5. The continuous metal casting method according to claim 4, characterized in that the lubricant is led from the lubricant reservoir to the lubricant supply port through a horizontal groove in the mold. 6. The continuous metal casting method according to any one of claims 1 to 5, characterized in that a heat insulating part is provided in the upper part of the mold located on the back side of the hanging part. .