JP2016175115A - Template for continuous casting, and continuous casting method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a longitudinal crack or breakout by performing slow cooling of a cast slab more stably, in continuous casting.SOLUTION: There is provided a template for continuous casting in which a molten metal or mold powder is supplied from an upper side, and a cast slab formed by solidifying the molten metal is extracted from a lower side. In the template for continuous casting, a heat resistance part for preventing cooling of the inside surface of a side wall in contact with a cast slab or the mold powder is provided inside the side wall. A continuous casting method using the template for continuous casting is also provided.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a continuous casting mold and a continuous casting method.

  In the continuous casting process, molten metal (for example, molten steel) is supplied to the mold from above, and the slab drawn from the lower end of the mold is cooled while being supported and conveyed by a plurality of pairs of support rolls. The slab is one in which the outer peripheral surface of the molten metal poured into the mold is cooled and solidified in the mold.

  Here, in the continuous casting process, vertical cracks and breakouts may occur in the slab during casting. One of the causes of the vertical cracks and breakouts has been found to be non-uniformity in the rate at which a solidified layer (solidified shell) is formed on the surface of the slab. In addition, it is known that it is effective to slowly cool the solidified shell in the mold (that is, to slowly cool the slab) in order to alleviate the unevenness of formation of the solidified shell. Therefore, a technology has been developed that suppresses vertical cracking and breakout of the slab by slowly cooling the slab using a mold powder solid layer existing between the slab and the inner wall of the mold.

  Here, the mold powder is a powder supplied from the upper part of the mold together with the molten metal in order to improve the lubrication between the slab and the inner wall of the mold. The liquid phase mold powder melted by the heat of the molten metal enters between the slab and the inner wall of the mold, so that the lubrication between the slab and the inner wall of the mold is maintained. On the other hand, since the mold is cooled during the continuous casting, the mold powder that has become liquid can be solidified in the vicinity of the inner wall of the mold to form a mold powder solid layer. The mold powder solid layer is present between the slab and the inner wall of the mold and serves as a heat insulating material, so that the slab can be slowly cooled.

  For example, Patent Document 1 discloses a mold powder having a relatively uniform desired heat transfer resistance by appropriately adjusting the composition of the mold powder and controlling the roughness of the contact surface of the mold powder solid layer with the inner wall of the mold. A technique for forming a solid layer and slowly cooling the slab more uniformly is disclosed. Further, for example, in Patent Document 2, by appropriately adjusting the composition of the mold powder and the roughness of the inner wall surface of the mold, the heat transfer resistance between the mold and the mold powder solid layer is made uniform, and more stable. A technique for realizing slow cooling of a slab is disclosed.

JP 11-291005 A Japanese Patent Laid-Open No. 10-263769

  Here, the mold powder solid layer is pulled out of the mold together with the slab while being attached to the outer peripheral surface of the slab during continuous casting. Therefore, the mold powder solid layer once formed is not permanently fixed to the inner wall of the mold, and the mold powder solid layer in the mold is considered to be updated as needed during continuous casting. In particular, when the casting speed is high, the speed at which the slab passes through the mold is increased, so that it is expected that the frequency with which the mold powder solid layer is renewed is also increased.

  When the mold powder solid layer is renewed, it is considered that there is a period in which the mold powder solid layer temporarily does not exist between the slab and the inner wall of the mold. During the period, the slab is slowly cooled. Might not be done properly. Thus, in the method of realizing the slow cooling of the slab by using the mold powder solid layer as a heat insulating material, there is a possibility that the slow cooling is not temporarily performed when the mold powder solid layer is updated, There is a risk that vertical cracks and breakouts cannot be sufficiently suppressed. In addition, since there may be a period in which the mold powder solid layer does not exist temporarily in the mold, there is a possibility that the inner wall of the mold and the slab are in direct contact and seizure occurs.

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is a new and improved technique capable of performing more stable slab cooling in continuous casting. Another object of the present invention is to provide a continuous casting mold and a continuous casting method.

  In order to solve the above-mentioned problem, according to one aspect of the present invention, there is provided a continuous casting mold in which molten metal and mold powder are supplied from above, and a cast piece solidified from the molten metal is drawn from below, A continuous casting mold is provided in which a heat resistance portion that prevents cooling of an inner surface of a side wall in contact with a slab or the mold powder is provided inside the side wall.

  In the continuous casting mold, the temperature of the inner surface of the side wall may be maintained at a temperature corresponding to the melting point of the mold powder by the thermal resistance portion.

  In the continuous casting mold, the temperature of the inner surface of the side wall may be maintained at 1000 ° C. to 1200 ° C. by the thermal resistance portion.

  In the continuous casting mold, the thermal resistance portion has a depth from the upper end of the continuous casting mold from a position where the depth from the upper end of the continuous casting mold is about 80 (mm). It may be formed at least for a region up to a position that is about 320 (mm).

  In the continuous casting mold, the thermal resistance portion may be provided in a range where the slab can exist in the depth direction of the continuous casting mold.

  Further, in the continuous casting mold, the thermal resistance portion is constituted by a slit member having a plurality of slits, and the thermal resistance is adjusted by adjusting at least one of the slit width and the slit interval of the slit member. The thermal resistance value of the part may be adjusted.

  Further, in the continuous casting mold, the thermal resistance portion is configured by filling a space of a predetermined width with a filler, the width of the space, the type of filler, and the filling rate of the filler. The thermal resistance value of the thermal resistance unit may be adjusted by adjusting at least one of them.

  Further, in the continuous casting mold, the continuous casting mold includes a cooling unit provided on the outermost side for cooling the continuous casting mold, and a heat-resistant mold provided on the innermost side and in contact with the slab or the mold powder. And the thermal resistance part that is provided between the heat resistant mold and the cooling part and suppresses heat transfer between the heat resistant mold and the cooling part.

  Further, in the continuous casting mold, the continuous casting mold is configured such that an auxiliary mold in which the thermal resistance portion is formed in a side wall is fitted into a cooling mold for cooling the continuous casting mold. Also good.

  In order to solve the above-mentioned problems, according to another aspect of the present invention, a continuous casting mold is used in which molten metal and mold powder are supplied from above, and the slab solidified by the molten metal is drawn from below. There is provided a continuous casting method, wherein a thermal resistance portion that prevents cooling of an inner surface of a side wall of the continuous casting mold in contact with the slab or the mold powder is provided inside the side wall. The

  Moreover, in the said continuous casting method, the said thermal resistance part may be formed with respect to the area | region whose depth from a molten metal surface is 100 (mm)-200 (mm) at least.

  In the continuous casting method, continuous casting may be performed without oscillation without vibrating the continuous casting mold.

  As described above, according to the present invention, the slab can be slowly cooled more stably in continuous casting.

It is a sectional side view showing the schematic structure of the continuous casting machine concerning one embodiment of the present invention. It is explanatory drawing for demonstrating the mode of cooling of the slab in the conventional casting_mold | template. It is a figure shown about the mode of the heat transfer between a casting_mold | template and a slab in the filling area | region of the conventional casting_mold | template. It is explanatory drawing for demonstrating the mode of cooling of the slab in the casting_mold | template which concerns on this embodiment. It is a figure shown about the mode of heat transfer between a mold and a slab in the filling area of the mold concerning this embodiment. It is a figure which shows the example of 1 structure of the casting_mold | template concerning this embodiment. It is a longitudinal cross-sectional view in the AA cross section shown in FIG. 6 of the casting_mold | template which concerns on this embodiment. It is a perspective view which shows one structural example of the auxiliary | assistant casting_mold | template which comprises the casting_mold | template which concerns on this modification. It is a top view of the auxiliary mold shown in FIG. It is sectional drawing which shows a mode that the auxiliary | assistant casting_mold | template shown in FIG.8 and FIG.9 was engage | inserted by the cooling casting_mold | template, and the casting_mold | template concerning this modification was comprised.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(1. Overall configuration of continuous casting machine)
First, a schematic configuration of a continuous casting machine according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a side sectional view showing a schematic configuration of a continuous casting machine according to an embodiment of the present invention. In addition, in the drawings shown below including FIG. 1, the size of some of the constituent members may be exaggerated for the sake of explanation, and the relative sizes of the constituent members illustrated in the respective drawings. This does not necessarily accurately represent the magnitude relationship between actual components.

  As shown in FIG. 1, a continuous casting machine 1 according to this embodiment is for continuously casting a molten metal 2 (for example, molten steel) using a casting mold 10 for producing a slab 3 such as a slab. Device. The continuous casting machine 1 includes a mold 10, a ladle 4, a tundish 5, an immersion nozzle 6, a secondary cooling device 7, and a slab cutting machine 8.

  The ladle 4 is a movable container for conveying the molten metal 2 from the outside to the tundish 5. The ladle 4 is disposed above the tundish 5, and the molten metal 2 in the ladle 4 is supplied to the tundish 5. The tundish 5 is disposed above the mold 10, stores the molten metal 2, and removes inclusions in the molten metal 2. The immersion nozzle 6 extends downward from the lower end of the tundish 5 toward the mold 10, and the tip thereof is immersed in the molten metal 2 in the mold 10. The immersion nozzle 6 continuously supplies the molten metal 2 from which inclusions have been removed in the tundish 5 into the mold 10.

  In the following description, the vertical direction (that is, the direction in which the molten metal 2 is supplied from the tundish 5 to the mold 10) is also referred to as the Z-axis direction. Two directions orthogonal to each other in a plane (horizontal plane) perpendicular to the Z-axis direction are also referred to as an X-axis direction and a Y-axis direction, respectively. Further, the X-axis direction is defined as a direction parallel to the long side of the mold 10, and the Y-axis direction is defined as a direction parallel to the short side of the mold 10.

  The mold 10 has a square tube shape corresponding to the width and thickness of the slab 3. Although not shown in FIG. 1, in this embodiment, a thermal resistance portion is provided inside the side wall of the mold 10. The heat resistance portion prevents cooling of the inner wall surface of the mold 10 in contact with the slab or the mold powder, thereby realizing a slow cooling of the slab 3. Specifically, in the heat resistance portion, the temperature of the inner wall surface of the mold 10 becomes a temperature at which the slab 3 can be slowly cooled, for example, a temperature corresponding to the melting point of the mold powder (for example, about 1000 ° C. to 1200 ° C.). As described above, the thermal resistance value is adjusted. Thereby, the temperature of the inner wall surface of the mold 10 is maintained at a relatively high temperature, and the slab 3 can be slowly cooled. The more specific configuration of the mold 10 will be described in detail again in the following (2-2. Outline of the present invention) and the following (3. Specific configuration example of the mold).

  The mold 10 cools the molten metal 2 to produce a slab 3 including an unsolidified portion 3b inside the solidified shell 3a of the outer shell. As the slab 3 moves toward the lower side of the mold 10, solidification of the inner unsolidified portion 3b proceeds, and the thickness of the outer solidified shell 3a gradually increases. The slab 3 including the solidified shell 3a and the unsolidified portion 3b is pulled out from the lower end of the mold 10. At this time, in the present embodiment, the mold 10 can achieve the slow cooling of the slab 3, whereby the speed at which the solidified shell 3 a is formed can be made more uniform in the plane of the slab 3, and vertical cracks can occur. Can be suppressed.

  Although not shown in FIG. 1, mold powder is supplied to the mold 10 together with the molten metal 2 from above. The supplied mold powder is melted by the heat of the molten metal 2, and the liquid mold powder is interposed between the cast piece 3 and the inner wall of the mold 10. Lubrication between the slab 3 and the inner wall of the mold 10 is maintained by the mold powder that has become the liquid.

  The secondary cooling device 7 is provided in the secondary cooling zone 9 below the mold 10 and cools the cast slab 3 drawn out from the lower end of the mold 10 while supporting and transporting it. The secondary cooling device 7 includes a plurality of pairs of support rolls (for example, a support roll 11, a pinch roll 12 and a segment roll 13) disposed on both sides in the thickness direction of the slab 3, and cooling water for the slab 3. A plurality of spray nozzles (not shown).

  The support rolls provided in the secondary cooling device 7 are arranged in pairs on both sides in the thickness direction of the slab 3 and function as a support and transport means for transporting the slab 3 while supporting it. By supporting the slab 3 from both sides in the thickness direction with the support roll, breakout and bulging of the slab 3 during solidification in the secondary cooling zone 9 can be prevented.

  The support roll 11, the pinch roll 12, and the segment roll 13, which are support rolls, form a transport path (pass line) for the cast piece 3 in the secondary cooling zone 9. As shown in FIG. 1, this pass line is vertical immediately below the mold 10, then curved in a curved shape, and finally becomes horizontal. In the secondary cooling zone 9, a portion where the pass line is vertical is called a vertical portion 9A, a curved portion is called a curved portion 9B, and a horizontal portion is called a horizontal portion 9C. The continuous casting machine 1 having such a pass line is referred to as a vertical bending type continuous casting machine 1. The present invention is not limited to the vertical bending type continuous casting machine 1 as shown in FIG. 1, but can be applied to other various continuous casting machines such as a curved type or a vertical type.

  The support roll 11 is a non-driven roll provided in the vertical portion 9 </ b> A immediately below the mold 10, and supports the cast piece 3 immediately after being pulled out from the mold 10. The slab 3 immediately after being drawn out from the mold 10 is in a state where the solidified shell 3a is thin, and therefore it is necessary to support it at a relatively short interval (roll pitch) in order to prevent breakout and bulging. Therefore, as the support roll 11, it is desirable to use a roll with a small diameter that can shorten the roll pitch. In the example shown in FIG. 1, three pairs of support rolls 11 made of small-diameter rolls are provided at a relatively narrow roll pitch on both sides of the slab 3 in the vertical portion 9A.

  The pinch roll 12 is a drive roll that is rotated by a driving means such as a motor, and has a function of pulling the slab 3 out of the mold 10. The pinch rolls 12 are respectively arranged at appropriate positions in the vertical portion 9A, the curved portion 9B, and the horizontal portion 9C. The slab 3 is pulled out of the mold 10 by the force transmitted from the pinch roll 12 and is conveyed along the pass line. In addition, arrangement | positioning of the pinch roll 12 is not limited to the example shown in FIG. 1, The arrangement position may be set arbitrarily.

  The segment roll 13 (also referred to as a guide roll) is a non-driving roll provided in the bending portion 9B and the horizontal portion 9C, and supports and guides the slab 3 along the pass line. The segment roll 13 depends on the position on the pass line, and on the F surface (Fixed surface, lower left surface in FIG. 1) and L surface (Loose surface, upper right surface in FIG. 1) of the slab 3, They may be arranged with different roll diameters and roll pitches.

  The slab cutting machine 8 is disposed at the end of the horizontal portion 9C of the pass line, and cuts the slab 3 conveyed along the pass line to a predetermined length. The cut thick plate-shaped slab 14 is transported to the next process equipment by the table roll 15.

  The overall configuration of the continuous casting machine 1 according to the present embodiment has been described above with reference to FIG. In addition, the continuous casting machine 1 which concerns on this embodiment respond | corresponds to what the structure of the casting_mold | template 10 was changed with respect to the general conventional continuous casting machine. The specific configuration of the continuous casting machine 1 is not limited to that shown in FIG. 1, and the mold 10 according to the present embodiment may be applied to various known continuous casting machine configurations.

  Moreover, the kind and size of the slab 3 manufactured by the continuous casting machine 1 are not specifically limited. For example, the slab 3 may be a slab having a thickness of about 250 to 300 (mm), a bloom or billet exceeding 500 (mm), or a thin slab having a thickness of about 100 (mm), It may be a continuous strip cast strip of 50 mm or less. Moreover, the raw material of the slab 3 should just be a metal which can be continuously cast, for example, various metals, such as aluminum, aluminum alloy, titanium other than steel and special steel, may be sufficient.

(2. Background to the present invention and outline of the present invention)
Here, prior to the detailed description of the configuration of the mold 10 according to the present embodiment, the contents of the studies made by the present inventors on the conventional mold will be described in order to clarify the present invention. In addition, the background that the inventors have conceived of the present invention based on the examination results will be described, and an outline of the present invention will be described.

(2-1. Configuration of conventional mold)
With reference to FIG. 2, the state of cooling of the slab in the conventional mold will be described. FIG. 2 is an explanatory diagram for explaining a state of cooling of a slab in a conventional mold. FIG. 2 shows a vertical cross-sectional view (cross-sectional view in the YZ plane) of one of the side walls corresponding to the long side of the conventional mold. When molten metal and mold powder are supplied to the mold, FIG. The state inside the mold is shown.

  Referring to FIG. 2, in the conventional mold 90, a cooling water path through which the cooling water 912 flows is provided inside the mold side wall 911. The mold side wall 911 is a plate-like member formed of a material having a relatively small thermal resistance value such as copper. In FIG. 2, only one mold side wall 911 is illustrated, but a quadrangular cylindrical mold 90 is configured by combining four mold side walls 911. The cooling water 912 supplied by a pump or the like (not shown) flows inside the mold side wall 911, so that the slab 3 (that is, the solidified shell 3 a and the unsolidified portion 3 b) inside the mold 90 passes through the mold side wall 911. To be cooled.

  Mold powder is supplied to the mold 90 together with molten metal from above. The mold powder is melted by the heat of the slab 3, and the mold powder that has become liquid flows between the solidified shell 3a and the inner wall of the mold 90 (that is, the inner wall of the mold side wall 911).

  Here, during casting, the temperature of the unsolidified portion 3b of the slab 3 is about 1580 ° C. to 1610 ° C., and the surface temperature of the slab 3 is also in the upper region of the mold 90 where the thickness of the solidified shell 3a is relatively thin. It may be a temperature according to this. However, as described above, since the mold side wall 911 is cooled, the surface temperature of the inner wall of the mold 90 is about 100 ° C. to 300 ° C., and the surface temperature of the solidified shell 3a in the lower region of the mold 90 is about 800 ° C. It has dropped to. On the other hand, the mold powder is, for example, a ternary oxide composed of aluminum oxide-silicon oxide-calcium oxide, and its melting point is about 1000 ° C. to 1200 ° C.

  Accordingly, the mold powder charged into the mold 90 can be melted and exist as a liquid in the upper region of the mold 90 due to the heat received from the slab 3, but for example, a contact region with the inner wall of the mold 90 or the mold 90. In the lower region, the temperature is lowered by the inner wall of the mold 90 and the solidified shell 3a whose temperature is relatively lowered, so that it can be solidified and exist as a solid. In particular, in the lower region of the mold 90, it is considered that mold powder that is mainly solid is interposed between the slab 3 and the inner wall of the mold 90.

  Thus, in the mold 90, in the upper region of the mold 90, there is a mold powder layer (mold powder liquid layer 21) that has become liquid and a mold powder layer (mold powder solid layer 22) that has become solid. It can be interposed between the inner wall of the mold 90 and the slab 3. In the lower region of the mold 90, the mold powder solid layer 22 can be interposed between the inner wall of the mold 90 and the cast piece 3.

  Here, various studies have been made on the inside of the mold 90 when molten metal and mold powder are supplied to the mold 90. As one of them, in the mold 90, there is a slight gap or almost no gap between the inner wall of the mold 90 and the mold powder solid layer 22 in a predetermined distance from the molten metal surface. In the region below the region, it has been found that a larger gap 24 exists between the inner wall of the mold 90 and the mold powder solid layer 22 (for example, Masahita HANAO, Masayuki KAWAMOTO and Akihiro YAMANAKA, ISIJ). International, 2009, Vol. 49, No. 3, pp. 365-374 (hereinafter referred to as non-patent document 1)).

In Non-Patent Document 1, as a result of measuring the heat flux (W / m ² ) on the inner wall of the mold 90 at a plurality of measurement points in the depth direction, the distance from the molten metal surface is 100 (mm) to 200 (mm). It is described that a rapid decrease in the heat flux was observed in a deeper region. As a result, in a region where the distance from the molten metal surface is deeper than 100 (mm) to 200 (mm), a layer having a larger thermal resistance value (that is, a smaller layer) is formed between the inner wall of the mold 90 and the slab 3. This indicates that a layer having thermal conductivity is present.

  Considering the measured heat flux value, the heat insulation effect due to the mold powder (ie, the heat resistance value of the mold powder), the heat insulation effect due to the air gap (ie, the heat resistance value of the air), the predicted value of the surface temperature of the slab 3, etc. As shown in FIG. 2, in the region where the depth from the molten metal surface is 100 (mm) to 200 (mm), there is a slight void or almost void in the range in contact with the inner wall of the mold 90. It is considered that the mold powder solid layer 22 is almost full. In addition, even if there is a gap in the region, the width is considered to be about several (μm) at most. In FIG. 2, the gap is not shown. In the following description, in the mold 90, the region in the depth direction in which the mold powder solid layer 22 is almost full (that is, the depth from the molten metal surface is 100 (mm) to 200 (mm). Area) is also referred to as a full area.

  On the other hand, from the consideration based on the measurement result of the heat flux, as shown in FIG. 2, in the region where the distance from the molten metal surface is deeper than 100 (mm) to 200 (mm), the range in contact with the inner wall of the mold 90 is not. It is considered that a relatively large gap 24 exists. The width of the gap 24 is considered to be about several tens to several hundreds (μm). The space 24 functions as a heat insulating material having a large heat insulating effect. In the following description, in the mold 90, the region in the depth direction in which the gap 24 is present (that is, the region whose depth from the molten metal surface is deeper than 100 (mm) to 200 (mm)). This is also referred to as an unfilled area.

  As described above, in the present embodiment, the boundary between the full area and the non-full area is the position where the depth from the molten metal surface is 100 (mm) to 200 (mm), but the numerical value is merely an example. It is. The boundary between the full area and the non-full area in the mold 90 can vary depending on the operating conditions such as the temperature of the mold 90 and the slab 3 and the material of the mold powder.

  As described above, from the description of documents such as Non-Patent Document 1, for example, the mold powder solid layer 22, the mold powder liquid layer 21, and the cast piece are in a positional relationship as shown in FIG. It is thought that exists. Here, it is said that in the conventional mold 90, the mold powder solid layer 22 functions as a heat insulating material, so that the slab 3 can be slowly cooled. The present inventors have examined in more detail how the slow cooling is realized in the conventional mold 90 based on the inside of the mold 90 shown in FIG.

  As described above, in the non-filled region, the relatively large gap 24 functions as a heat insulating material having a large heat insulating effect. Therefore, in the unfilled region, it is considered that the slab 3 can be slowly cooled by the gap 24 regardless of the presence or absence of the mold powder solid layer 22.

  Therefore, the present inventors paid attention to the full area and considered the heat transfer between the mold 90 and the cast piece 3 in the full area. The result of consideration is shown in FIG. FIG. 3 is a diagram showing a state of heat transfer between the mold 90 and the slab 3 in a full region of the conventional mold 90.

  In FIG. 3, a configuration related to heat transfer in a full region of the conventional mold 90 is schematically illustrated. As shown in the drawing, in the filling region of the conventional mold 90, the cooling water 912, the mold side wall 911, the gap 23, the mold powder solid layer 22, the mold powder liquid layer 21, and the solidified shell 3a in this order are in this order. Existing. The gap 23 is a gap that is not shown in FIG. 2 and may exist between the mold side wall 911 and the mold powder solid layer 22 in the full region. Assuming that slow cooling of the slab 3 (ie, slow cooling of the solidified shell 3a) is realized, the surface temperature of the solidified shell 3a is set to a temperature (1229 ° C.) at which it is considered that slow cooling is realized. The temperature at the boundary between the members can be calculated when the following values are obtained. In addition, as the temperature (30 ° C.) at the boundary between the cooling water 912 and the mold side wall 911, the temperature value of the cooling water 912 actually used for the operation was used.

Cooling water 912-mold side wall 911: 30 ° C
Mold side wall 911-gap 23: 76 ° C
Void 23-Mold powder solid layer 22: 903 ° C
Mold powder solid layer 22-Mold powder liquid layer 21: 1098 ° C
Mold powder liquid layer 21-solidified shell 3a: 1229 ° C

  In the above calculation, the conditions shown in Table 1 below were used. Here, the width of the mold side wall 911 and the thermal resistance value, the thermal resistance value of the mold powder solid layer 22, and the thermal resistance value of the mold powder liquid layer 21 were values of substances actually used for operation. Moreover, the predicted value based on various literature etc. was used for the width | variety of the space | gap 23, the width | variety of the mold powder solid layer 22, and the width | variety of the mold powder liquid layer 21. FIG. Here, the width of each component shown in Table 1 below represents the length in the horizontal direction of the paper in FIG. In the following description, when the heat transfer is described, if it is simply described as the width, it means the length of each component in the heat transfer direction unless otherwise specified.

  Referring to the above calculation results, a large temperature difference of about 800 ° C. is realized between the materials by the interstices 23, and a temperature difference of about 200 ° C. is realized between the materials by the interposition of the mold powder solid layer 22. I understand. Thus, in the conventional mold 90, it can be said that the slab 3 is slowly cooled due to the presence of the gap 23 and the mold powder solid layer 22.

  Here, the mold powder solid layer 22 is pulled out from the mold 90 together with the cast piece 3 while being attached to the outer peripheral surface of the cast piece 3 during continuous casting. Therefore, the mold powder solid layer 22 once formed is not permanently fixed to the inner wall of the mold 90, and the mold powder solid layer 22 inside the mold 90 is updated at any time during continuous casting. It is thought that there is.

  When the mold powder solid layer 22 is updated, a period in which the mold powder solid layer 22 does not temporarily exist between the slab 3 and the inner wall of the mold 90 may occur. 2 and 3, it is considered that the mold powder liquid layer 21 is filled between the mold side wall 911 and the solidified shell 3a during the period in which the mold powder solid layer 22 does not exist. As described above, in the conventional mold 90, it is considered that the slab 3 is slowly cooled due to the presence of the gap 23 and the mold powder solid layer 22. Cooling may not be performed properly.

  When the mold powder solid layer 22 does not exist and only the mold powder liquid layer 21 is interposed between the mold side wall 911 and the solidified shell 3a, the solidified shell 3a (that is, the cast piece) 3 surface) may come into contact with the inner surface of the mold side wall 911. When the solidified shell 3a comes into contact with the inner surface of the mold side wall 911 and is rapidly cooled, so-called seizure may occur.

  In the above, the result which the present inventors examined about the slow cooling in the conventional casting_mold | template 90 was demonstrated. As described above, in the conventional mold 90, the slab 3 and the mold powder solid layer 22 are present between the mold side wall 911 and the slab 3 so that the slab 3 is slowly cooled. it is conceivable that. However, since the mold powder solid layer 22 is updated at any time during the continuous casting, there is a possibility that a period in which the mold powder solid layer 22 is not present may occur, and the slab 3 is not appropriately slowly cooled during the period. There is a fear.

  Based on the knowledge obtained from the above-described investigation results, the present inventors have intensively studied a technique capable of more slowly cooling the slab 3 more stably, and as a result, a preferred embodiment of the present invention is obtained. I came up with it. As described above (1. Overall configuration of continuous casting machine), in a preferred embodiment of the present invention, the thermal resistance portion is provided inside the side wall of the mold 10. The temperature of the inner wall surface of the mold 10 is maintained at a temperature at which the slab 3 can be slowly cooled by the heat resistance portion, so that the slab 3 can be more stable regardless of the presence or absence of the mold powder solid layer 22. It is possible to cool slowly.

(2-2. Summary of the present invention)
Hereinafter, with reference to FIG. 4, while explaining the schematic structure of the casting_mold | template which concerns on suitable one Embodiment of this invention, the outline | summary of this invention is demonstrated. FIG. 4 is an explanatory diagram for explaining the state of cooling of the cast piece in the mold according to the present embodiment. In FIG. 4, as in FIG. 2, a longitudinal sectional view (a sectional view in the YZ plane) of one of the side walls corresponding to the long side of the mold according to the present embodiment is shown. And the inside of the mold when the mold powder is supplied. In addition, in FIG. 4, the boundary of the full area | region and non-full area | region demonstrated with reference to FIG. 2 is shown collectively for description.

  Referring to FIG. 4, the mold 10 according to the present embodiment is configured by providing a thermal resistance portion inside the side wall. For example, as shown in the drawing, the side wall of the mold 10 is provided on the outermost side, a cooling unit 110 that cools the mold 10, an innermost heat-resistant mold 130 that contacts the slab 3 or mold powder, and a heat-resistant mold 130. The heat resistance part 120 is provided between the cooling part 110 and suppresses heat transfer between the two.

  The cooling unit 110 includes, for example, a cooling mold 111 and a cooling water path through which the cooling water 112 formed inside the cooling mold 111 flows. The cooling mold 111 is a rectangular tube-shaped member configured by combining plate members formed of a material having a relatively small thermal resistance value such as copper. In FIG. 4, only a portion corresponding to one side wall of the cooling mold 111 is illustrated, but the rectangular cylindrical cooling mold 111 is configured by combining four plate-like members. The cooling water 112 supplied by a pump or the like (not shown) flows in the cooling mold 111, whereby the cooling mold 111 is cooled.

  The heat-resistant mold 130 is a square tube-shaped member having dimensions corresponding to the width and thickness of the slab 3. In FIG. 4, only a portion corresponding to one side wall of the heat-resistant mold 130 is illustrated, but actually, a rectangular tube-shaped heat-resistant mold 130 is configured by combining four plate-like members. The heat-resistant mold 130 is formed of a refractory material such as tungsten heat-resistant steel, molybdenum heat-resistant steel, or SiC. The heat-resistant mold 130 is a part that constitutes the innermost wall of the mold 10 and is a part that directly contacts the high-temperature mold powder liquid layer 21 or the cast piece 3. Therefore, the heat-resistant mold 130 can be formed of a material having a melting point higher than that of the cast slab 3 or the mold powder, such as the exemplified heat-resistant steel of tungsten.

  The thermal resistance part 120 is configured by a member having a predetermined thermal resistance value such that the temperature of the inner wall surface of the heat-resistant mold 130 becomes a desired temperature. Specifically, the material constituting the heat resistance portion 120 and the width of the heat resistance portion 120 are appropriately designed so that the surface temperature of the inner wall of the heat-resistant mold 130 is a temperature at which the slab 3 can be slowly cooled. Is done. For example, the material constituting the heat resistance part 120 and the width of the heat resistance part 120 are appropriately adjusted so that the surface temperature of the inner wall of the heat-resistant mold 130 is about 1000 ° C. to 1200 ° C., which is the melting point of the mold powder. . As a result, the surface temperature of the inner wall of the heat-resistant mold 130 is substantially the same as the temperature at the boundary between the mold powder solid layer 22 and the mold powder liquid layer 21 when it is assumed that the conventional mold 90 achieves slow cooling. It is controlled to become. As described above, in the present embodiment, the heat insulation between the inner wall of the mold 90 and the slab 3, which is conventionally realized by the mold powder solid layer 22, is realized by the heat resistance portion 120 provided inside the mold 10. It is.

  Here, as described in (2-1. Conventional mold), in order to achieve slow cooling of the slab 3, heat insulation between the inner wall of the mold 10 and the slab 3 in the full region is performed. Is important. Therefore, as shown in the drawing, the thermal resistance portion 120 can be provided at least in a region corresponding to the full region (that is, a region having a depth from the molten metal surface of 100 (mm) to 200 (mm)). This is because a relatively large gap 24 may exist in the non-filled region, and thus heat insulation capable of realizing slow cooling can be realized without the heat resistance portion 120.

  Here, generally, the position of the molten metal surface in the mold 10 during casting is such that the upper end of the mold 10 does not become too hot, and the molten metal does not scatter even if the molten metal surface fluctuates relatively greatly. For safety reasons such as the above, in many cases, the position is 80 (mm) to 120 (mm) from the upper end of the mold 10. Considering this, when the upper end of the mold 10 is used as a reference, a region where a full region can be assumed is from the position where the depth from the upper end of the mold 10 is about 80 (mm). It is considered that the region reaches a position where the depth from the upper end is 320 (mm). Accordingly, the thermal resistance portion 120 also has a depth from the upper end of the mold 10 of about 320 (mm) from a position where the depth from the upper end of the mold 10 is about 80 (mm) corresponding to the region. It can be provided at least in the region up to the position.

  The specific configuration of the thermal resistance unit 120 is not limited. For example, the thermal resistance unit 120 can be configured by a slit member having a plurality of slits. The slit member can be formed of tungsten, which is the same material as the heat-resistant mold 130, for example. Copper or tungsten itself is a substance having a relatively small thermal resistance value. By processing these metals into a slit shape, a slit member having a relatively large thermal resistance value that can function as the thermal resistance unit 120 is formed. Can be realized. By appropriately adjusting the width of the slit member itself, the slit width, and the slit interval, the thermal resistance value of the thermal resistance unit 120 can be appropriately controlled to a desired value. Such a configuration example will be described later with reference to FIG.

As another configuration example of the thermal resistance unit 120, the thermal resistance unit may be configured by filling various fillers in a space having a predetermined width. As the filler, powders such as BN, SiC, Si ₃ N ₄ , and Al ₂ O ₃ can be used. These substances are known to have a thermal resistance value of about 1.0 to 50 (W / (m · ° C.)). The thermal resistance unit 120 can be configured by providing a space between the cooling unit 110 and the heat-resistant mold 130 and filling the space with at least one of the exemplified fillers. By appropriately adjusting the width of the space, the type of filler to be filled, and the filling rate (density), the thermal resistance value of the thermal resistance unit 120 can be appropriately controlled to a desired value.

  In addition, the thermal resistance value calculated | required by the thermal resistance part 120 may change with operating conditions, such as the temperature of the slab 3, and the kind of mold powder. Therefore, it is desirable that the thermal resistance unit 120 be configured such that its thermal resistance value can be changed more easily. For example, when the thermal resistance unit 120 is configured by a slit member, when changing the thermal resistance value, the slit member itself is replaced with another slit member processed to have a different thermal resistance value. It is necessary and work may be troublesome. On the other hand, when the thermal resistance unit 120 is configured with a filler, the thermal resistance value can be changed only by changing the type and amount of the filler to be used, so that the operation is relatively easy. Thus, it is preferable that the heat resistance part 120 is comprised with a filler from a viewpoint of changing a thermal resistance value more easily.

  Here, with reference to FIG. 5, the design method of the thermal resistance part 120 is demonstrated. FIG. 5 is a diagram showing a state of heat transfer between the mold 10 and the cast piece 3 in the full region of the mold 10 according to the present embodiment. In FIG. 5, similarly to FIG. 3, a configuration related to heat transfer in a full region of the mold 10 is schematically illustrated.

  As shown in the figure, in the filling region of the mold 10, the cooling water 112, the cooling mold 111, the slit member 121, the heat resistant mold 130, the mold powder liquid layer 21, and the solidified shell 3a in the cooling water path can exist in this order. . Here, the slit member 121 is an example of the thermal resistance unit 120 described above, and is formed, for example, of tungsten in a slit shape. In addition, here, as an example, the heat-resistant mold 130 is made of tungsten, and the width thereof is 10 (mm).

  As described above, in the mold 10 according to this embodiment, the heat insulation between the inner wall of the mold 10 and the slab 3, which has been conventionally performed by the mold powder solid layer 22, is replaced with the mold powder solid layer 22. This is performed by the resistance unit 120. Therefore, the surface temperature of the inner wall of the heat-resistant mold 130 is substantially the same as the temperature at the boundary between the mold powder solid layer 22 and the mold powder liquid layer 21 when it is assumed that slow cooling is realized in the conventional mold 90. In this way, the width and material of the thermal resistance unit 120 may be adjusted. This means that the width and material of the thermal resistance portion 120 are adjusted so that the temperature of the inner wall surface of the heat-resistant mold 130 (that is, the inner wall surface of the mold 10) becomes a temperature corresponding to the melting point of the mold powder. doing.

  Specifically, the width and material of the thermal resistance portion 120 are appropriately designed so that the surface temperature of the inner wall of the heat-resistant mold 130 becomes a desired temperature by performing a simulation on a calculation model simulating the mold 10. Good. Alternatively, while actually producing a prototype of the mold 10 and actually performing continuous casting with the actual machine of the continuous casting machine using the prototype, the width and material of the thermal resistance portion 120 are finely adjusted according to the operating conditions. May be. In this case, for example, by installing a thermometer such as a thermocouple on the inner wall surface of the heat resistant mold 130, the surface temperature of the inner wall of the heat resistant mold 130 becomes a desired temperature based on the measured value of the thermometer. In addition, the width and material of the thermal resistance unit 120 may be adjusted as appropriate.

  An example of calculating the temperature at the boundary between the components in the case where the thermal resistance unit 120 is adjusted as described above and the slow cooling is realized is shown below. Moreover, the width | variety and thermal resistance value of each structure at this time are shown in Table 2 below. In the following calculation, the cooling mold 111 is assumed to have the same configuration as the mold side wall 911 of the conventional mold 90. That is, the width and thermal resistance value of the cooling mold 111 are the same as those values in the mold side wall 911 shown in Table 1 above. Moreover, the value of the thing actually used for the operation was used for the temperature of the cooling water and the thermal resistance value of the mold powder liquid layer 21. Furthermore, the predicted value based on various documents etc. was used for the width of the mold powder liquid layer 21.

Cooling water 112-cooling mold 111: 30 ° C.
Cooling mold 111-slit member 121 (thermal resistance portion 120): 76 ° C.
Slit member 121 (thermal resistance portion 120) -heat resistant mold 130: 1011 ° C
Heat-resistant mold 130—mold powder liquid layer 21: 1098 ° C.
Mold powder liquid layer 21-solidified shell 3a: 1229 ° C

  Referring to the above calculation results, by adjusting the width and thermal resistance value of the slit member 121 (that is, the thermal resistance portion 120) as appropriate, a large temperature difference of about 1000 ° C. is caused between the cooling mold 111 and the heat resistant mold 130. It can be seen that This also shows that the surface temperature of the solidified shell 3a is maintained at a temperature (1229 ° C.) at which it is considered that slow cooling is realized. Thus, in the casting_mold | template 10 which concerns on this embodiment, the moderate cooling of the slab 3 can be implement | achieved by adjusting the heat resistance part 120 suitably.

  In the above example, as an example, the heat-resistant mold 130 is made of tungsten and the width thereof is 10 (mm). However, when the material and width of the heat-resistant mold 130 are changed, Accordingly, the width and thermal resistance value of the thermal resistance unit 120 can be adjusted as appropriate. Further, in the above example, when the thermal resistance unit 120 is configured by the slit member 121, the width and the thermal resistance value required for the slit member 121 are determined. However, the thermal resistance unit 120 is configured by another member. In this case, the width and thermal resistance value of the member can be adjusted as appropriate. For example, if the thermal resistance portion 120 is configured by a filler, the width of the space filled with the filler and the type of filler so that the temperature of the inner wall surface of the heat-resistant mold 130 is maintained at a desired value. The filler filling rate and the like can be appropriately adjusted.

  Heretofore, the schematic configuration of the mold 10 according to the present embodiment has been described, and the overview of the present invention has been described. As described above, according to the present embodiment, the temperature of the inner wall surface of the heat-resistant mold 130 (that is, the inner wall surface of the mold 10) is changed to the mold powder by providing the thermal resistance portion 120 in the side wall of the mold 10. Is maintained at a temperature corresponding to the melting point (for example, 1000 ° C. to 1200 ° C.). Therefore, the heat resistance part 120 will fulfill | perform the function as a heat insulating material which the mold powder solid layer 22 was bearing in the conventional casting_mold | template 90 instead, and the slab 3 can be cooled slowly.

  Here, in the conventional mold 90, since the heat insulation is performed by the mold powder solid layer 22 that can be updated as needed, the slab 3 may not be appropriately cooled. On the other hand, according to the present embodiment, since the slab 3 is slowly cooled by the thermal resistance portion 120 that is always provided inside the side wall of the mold 10, it is possible to perform more stable slow cooling. Therefore, according to this embodiment, generation | occurrence | production of a vertical crack and a breakout can be suppressed more.

  Further, according to the present embodiment, as described above, the temperature of the inner wall surface of the heat-resistant mold 130 is maintained at a relatively high temperature corresponding to the melting point of the mold powder. Even if they come into contact with each other, image sticking hardly occurs. Thus, the effect of suppressing image sticking can be obtained by using the mold 10. Here, generally, in continuous casting of steel, control (oscillation) is performed in which the mold is periodically and continuously vibrated in the casting direction in order to prevent seizure between the inner wall of the mold and the slab. ing. By using the mold 10 according to the present embodiment, as described above, even if the inner wall of the mold 10 and the slab 3 come into contact with each other, seizure hardly occurs, so that continuous casting without oscillation is possible. .

(3. Specific configuration example of mold)
A specific configuration example of the mold 10 according to the present embodiment will be described with reference to FIGS. FIG. 6 is a diagram illustrating a configuration example of the mold 10 according to the present embodiment. FIG. 6 is a cross-sectional view in the horizontal plane of the mold 10, and shows a cross-sectional view in a plane passing through the full area. FIG. 7 is a longitudinal sectional view of the mold 10 according to the present embodiment, taken along the line AA shown in FIG.

  6 and 7, the mold 10 according to the present embodiment includes a cooling unit 110 that is provided on the outermost side and cools the mold 10, and a heat-resistant mold 130 that is provided on the innermost side and is in contact with the slab 3 or mold powder. And a heat resistance part 120 provided between the heat-resistant mold and the cooling part to suppress heat transfer between the two.

  The heat resistant mold 130 corresponds to the heat resistant mold 130 shown in FIGS. 4 and 5. 4 and 5 show cross-sectional views of one side wall, but as shown in FIG. 6, the heat-resistant mold 130 has a rectangular tube shape corresponding to the width and thickness of the slab 3. The heat-resistant mold 130 is configured by combining a plate-shaped member formed of a material having a melting point higher than that of the slab 3 and the mold powder. The heat resistant mold 130 is formed of, for example, a heat resistant steel such as tungsten or molybdenum, or a refractory material such as SiC.

  In addition, the heat-resistant mold 130 may be configured to be movable in the direction in which the short sides thereof face each other (X-axis direction shown in FIG. 6), similarly to the mold generally used when casting the slab. . Thereby, in the heat-resistant mold 130, the ratio of the length and width in the horizontal plane (that is, the length corresponding to the thickness and width of the slab 3) can be made variable.

  The cooling unit 110 includes a cooling mold 111 and a cooling water path formed inside the cooling mold 111 and through which the cooling water 112 flows. The cooling unit 110 corresponds to the cooling unit 110 illustrated in FIGS. 4 and 5. The cooling mold 111 is formed of a material having a relatively small thermal resistance value such as copper. Cooling water 112 circulates in the cooling water path by a pump (not shown) or the like. The mold 10 is cooled by the cooling water 112 flowing through the cooling water path inside the cooling mold 111.

  4 and 5, the sectional view of one side wall is shown. However, as shown in FIG. 6, the cooling mold 111 is arranged so that the plate-shaped member surrounds the outer periphery of the heat-resistant mold 130. It has a substantially rectangular tube shape. Each plate member constituting the cooling mold 111 is connected to the heat-resistant mold 130 by a bolt 140. When the cooling mold 111 and the heat-resistant mold 130 are connected by bolts, the difference in thermal expansion between the two materials (for example, the heat of copper constituting the cooling mold 111 and tungsten constituting the heat-resistant mold 130). In consideration of the difference in expansion, it is preferable that a predetermined play is provided between the two.

  A thermal resistance unit 120 is provided between the cooling mold 111 and the heat-resistant mold 130 on the side wall of the mold 10. The thermal resistance unit 120 can be configured by embedding a member made of a material having a thermal resistance value smaller than that of the heat resistant mold 130 in a space having a predetermined width. For example, the thermal resistance unit 120 may be configured by a slit member 121 illustrated in FIG. In this case, the material of the slit member 121, the width of the slit member 121 itself in the Y-axis direction, the slit width and the slit interval of the slit member, and the like are adjusted as appropriate, whereby the thermal resistance value ( That is, the thermal resistance value as the thermal resistance unit 120 can be adjusted.

  Further, for example, as described in (2-2. Outline of the present invention), the thermal resistance unit 120 may be configured by filling a space with various fillers. In this case, the thermal resistance value as the thermal resistance portion 120 can be adjusted by appropriately adjusting the width of the space, the material of the filler, the filling rate of the filler, and the like.

  For example, the thermal resistance value of the thermal resistance unit 120 is appropriately adjusted so that the temperature of the inner wall surface of the heat-resistant mold 130 is about 1000 ° C. to 1200 ° C., which is a temperature corresponding to the melting point of the mold powder. Thereby, as explained in the above (2-2. Outline of the present invention), the thermal resistance portion 120 of the mold powder solid layer 22 when the slab 3 is slowly cooled in the conventional mold 90 is realized. As a result, the slab 3 can be slowly cooled more stably.

  Moreover, as shown in FIG. 7, the thermal resistance part 120 can be provided only in a partial region in the depth direction. For example, the heat resistance portion 120 corresponds to the full area, and the depth from the molten metal surface is 100 (mm) to 200 (mm) (that is, the depth from the upper end of the mold 10 is about 80 (mm). To a position where the depth from the upper end of the mold 10 is about 320 (mm). As described in the above (2-1. Conventional mold), the non-filled area, which is the area below the full area, has a relatively large gap 24. This is because even if 22 does not exist, it is considered that the slab 3 can be slowly cooled. However, this embodiment is not limited to such an example, and the thermal resistance portion 120 is provided from the upper end of the side wall to a depth corresponding to the lower end (that is, for a region where the slab 3 can exist in the depth direction). May be.

  The specific configuration example of the mold 10 according to the present embodiment has been described above with reference to FIGS. 6 and 7.

(4. Modifications)
The configuration of the mold according to the present embodiment is not limited to the configuration described above (3. Specific configuration example of the mold). The mold according to the present embodiment may have other configurations. Here, another configuration example of the mold according to the present embodiment will be described as a modification of the present embodiment.

  With reference to FIGS. 8-10, the other example of a structure of the casting_mold | template which concerns on this embodiment is demonstrated. FIG. 8 is a perspective view showing one structural example of the auxiliary mold constituting the mold according to this modification. FIG. 9 is a top view of the auxiliary mold shown in FIG. FIG. 10 is a cross-sectional view showing a state in which the auxiliary mold shown in FIGS. 8 and 9 is fitted into the cooling mold, and the mold according to this modification is configured. FIG. 10 is a cross-sectional view in the vertical plane of the mold according to this modification, and shows a cross-sectional view in a plane passing through the vicinity of the approximate center of the long side of the mold.

  As shown in the figure, the mold 40 according to this modification is configured by fitting the auxiliary mold 30 into a cooling mold 410. The auxiliary mold 30 is a member having a rectangular tube shape that is formed of the same material (for example, tungsten) as that of the heat-resistant mold 130 described above. In the opening on the upper side of the auxiliary mold 30, an ear portion 310 extending in a horizontal plane toward the outside is formed. As shown in FIG. 10, the auxiliary mold 30 is fitted into the cooling mold 410 so that the ear 310 is placed on the shoulder of the opening of the cooling mold 410.

  A side wall of the auxiliary mold 30 is cut out by a predetermined depth in the vertical direction, and a space is formed in the side wall. A member made of a material having a thermal resistance value larger than that of the auxiliary mold 30 is embedded in the space, whereby the thermal resistance unit 320 is configured. As described above, the side wall of the auxiliary mold 30 has a three-layer structure including the inner wall, the outer wall, and the thermal resistance portion 320 existing between the inner wall and the outer wall. The inner wall of the auxiliary mold 30 is a part that directly contacts the slab 3 or the mold powder, and plays the same role as the heat-resistant mold 130 in the above-described embodiment. In addition, the outer wall of the auxiliary mold 30 is a part in contact with the inner wall of the cooling mold 410, and can constitute a part of the cooling unit 110 in the above-described embodiment.

  The thermal resistance unit 320 has the same configuration and function as the thermal resistance unit 120 in the above-described embodiment. For example, the thermal resistance unit 320 may be configured by embedding slit members formed of various materials, various fillers, and the like in the same manner as in the above-described embodiment. In addition, the width of the thermal resistance part 320 and the members constituting the thermal resistance part 320 are such that the temperature of the inner wall surface of the auxiliary mold 30 is a predetermined temperature at which the slab 3 can be slowly cooled (for example, the melting point of the mold powder). The temperature is appropriately adjusted so as to be about 1000 ° C to 1200 ° C.

  In the illustrated example, the thermal resistance portion 320 is provided up to a depth corresponding to the lower end of the auxiliary mold 30, that is, in a region where the slab 3 can exist in the depth direction. However, the depth at which the thermal resistance portion 320 is provided is not limited to this example, and the thermal resistance portion 320 has a depth of at least 100 (mm) from the molten metal surface corresponding to the full area, like the thermal resistance portion 120. ) To 200 (mm) (that is, from a position where the depth from the upper end of the mold 10 is about 80 (mm) to a position where the depth from the upper end of the mold 10 is about 320 (mm). Area).

  The cooling mold 410 is configured by combining metal plates having a relatively small thermal resistance value, such as copper, and has a rectangular tube shape that covers the outer periphery of the auxiliary mold 30. Although not shown in FIG. 10, the cooling mold 410 is appropriately provided with a cooling water path through which cooling water flows, similarly to the cooling mold 111 shown in FIGS. 6 and 7. As the cooling water circulates, the mold 40 is cooled.

  When the auxiliary mold 30 is fitted into the cooling mold 410 and the mold 40 is configured, as shown in FIG. 10, a lid 420 that closes the upper portion of the thermal resistance portion 320 may be provided. The lid 420 is made of the same material as that of the auxiliary mold 30, for example. For example, when the heat resistance unit 320 is formed of a filler, the filler 420 can prevent the filled filler from leaking to the outside. In FIG. 10, in order to facilitate understanding of the configuration of the mold 40, a space is illustrated between the outer wall of the auxiliary mold 30 and the inner wall of the cooling mold 410. The outer wall of the mold 30 and the inner wall of the cooling mold 410 may be in close contact.

  As described above, with reference to FIGS. 8 to 10, another configuration example of the mold according to the present embodiment has been described as a modification of the present embodiment. As described above, the mold 40 according to this modification is configured by fitting the auxiliary mold 30 in which the thermal resistance portion 320 is formed in the side wall into the cooling mold 410. Even in this configuration, as in the mold 10 according to the above-described embodiment, a structure in which the thermal resistance portion 320 is formed in the side wall is realized, so that the slab 3 can be slowly cooled more stably. become.

  In this modification, a conventionally used mold can be used as it is as the cooling mold 410. That is, the mold 40 according to this modification may be realized by combining the auxiliary mold 30 with an existing mold. In this case, since the cost of repairing the equipment can be suppressed by diverting the existing mold, the mold 40 can be manufactured at a lower cost.

  Here, as shown in FIGS. 8 to 10, the auxiliary mold 30 has a variable ratio of length and width in the horizontal plane (that is, a length corresponding to the thickness and width of the slab 3). It is difficult to configure. Therefore, the mold 40 according to this modification can be suitably applied to a mold in which the ratio of length to width in a horizontal plane is fixed, for example, generally called a tubular mold. On the other hand, in the mold 10 shown in FIGS. 6 and 7, the short sides of the heat-resistant mold 130 are opposed to each other (the X axis shown in FIG. The ratio of length to width in the horizontal plane can be variably configured. Therefore, the casting_mold | template 10 which concerns on embodiment mentioned above can be applied suitably at the time of casting of a slab, for example.

  In order to confirm the effect of the present invention, an example in which the mold 10 according to the present embodiment described above is applied to a continuous casting machine for an actual product in a steel plant will be described. As an example, the mold 10 shown in FIGS. 6 and 7 is applied to one mold of a two-strand continuous casting machine, and the conventional mold schematically shown in FIGS. 2 and 3 is applied to the other mold. 90 was applied and continuous casting was performed.

  Here, the 2-strand continuous casting machine is a continuous casting machine that supplies molten steel from one tundish to two molds. In the two-strand continuous casting machine, one mold is an example to which the mold 10 according to the present embodiment is applied, and the other mold is a comparative example to which the conventional mold 90 is applied. The effect of the present invention can be confirmed when continuous casting is performed on the molten steel.

  The casting speed in continuous casting was 1.0 (m / min) to 1.2 (m / min) in both the examples and comparative examples. In addition, the molds used in both Examples and Comparative Examples were those having a width of 1000 (mm) to 1500 (mm) and a thickness of 250 (mm).

  The configuration between the mold 90 and the slab 3 in the comparative example is considered to be the configuration shown in FIG. Moreover, it is assumed that the width | variety and thermal resistance value of each structure at this time are what are shown in the said Table 1. FIG.

On the other hand, the configuration between the mold 10 and the slab 3 in the example is considered to be the configuration shown in FIG. However, in the example, a configuration in which Al ₂ O ₃ particles (filler) were filled was used as the thermal resistance portion 120 instead of the slit member 121 shown in FIG. Moreover, the formation depth of the thermal resistance part 120 was 150 (mm) from the molten metal surface.

The width and the thermal resistance value of the heat resistance portion 120 by the Al ₂ O ₃ filler are set so that the temperature of the inner wall surface of the heat resistant mold 130 becomes the temperature shown in FIG. 5, that is, the heat resistance portion 120 by the Al ₂ O ₃ filler. Is appropriately adjusted so as to have the same heat conduction property as the slit member 121. Specifically, the width and the thermal resistance value of the thermal resistance portion 120 by the Al ₂ O ₃ filler are 10.5 (mm) and 17.3 (W / (m · K)), respectively. The filling rate of ₂ O ₃ filler and the like were appropriately adjusted. In summary, the width and thermal resistance value of each component in the example are as shown in Table 3 below.

  Under the above conditions, 100-charge continuous casting was performed. As a result, in the comparative example using the conventional mold 90, vertical cracks occurred at a rate of about 5%. On the other hand, in the Example using the casting_mold | template 10 which concerns on this embodiment, the incidence rate of the vertical crack was about 0.98%. Thus, it was confirmed that the occurrence of vertical cracks can be reduced by using the mold 10 according to the present embodiment. Conventionally, the mold 3 is cooled slowly by the mold powder solid layer 22, whereas in the mold 10, the mold 3 is slowly cooled by the heat resistance portion 120 provided in the side wall of the mold 10. Therefore, it is considered that the slow cooling is performed more stably.

  In the above, the Example which applied the casting_mold | template 10 which concerns on this embodiment with respect to the continuous casting machine for actual products in a steel plant was demonstrated. As described above, it has been confirmed that the use of the mold 10 according to the present embodiment reduces the occurrence of vertical cracks as compared with the case where the conventional mold 90 is used. Therefore, according to this invention, generation | occurrence | production of the inferior goods in continuous casting can be suppressed and a product yield can be improved.

(5. Supplement)
The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 1 Continuous casting machine 2 Molten metal 3 Slab 4 Ladle 5 Tundish 10, 40 Mold 30 Auxiliary mold 110 Cooling part 111, 410 Cooling mold 120, 320 Thermal resistance part 121 Slit member 130 Heat resistant mold

Claims (12)

A continuous casting mold in which molten metal and mold powder are supplied from above, and a cast piece solidified by the molten metal is drawn from below,
A thermal resistance portion that prevents cooling of the inner surface of the side wall in contact with the slab or the mold powder is provided inside the side wall.
Continuous casting mold. The temperature of the inner surface of the side wall is maintained at a temperature corresponding to the melting point of the mold powder by the thermal resistance portion.
The continuous casting mold according to claim 1. The temperature of the inner surface of the side wall is maintained at 1000 ° C. to 1200 ° C. by the thermal resistance portion.
The continuous casting mold according to claim 2. The thermal resistance portion is located from a position where the depth from the upper end of the continuous casting mold is about 80 (mm) to a position where the depth from the upper end of the continuous casting mold is about 320 (mm). At least formed with respect to the region,
The casting mold for continuous casting according to any one of claims 1 to 3. The thermal resistance portion is provided in a range where the slab can exist in the depth direction of the continuous casting mold,
The casting mold for continuous casting according to any one of claims 1 to 4. The thermal resistance portion is constituted by a slit member having a plurality of slits,
By adjusting at least one of the slit width and the slit interval of the slit member, the thermal resistance value of the thermal resistance portion is adjusted,
The casting mold for continuous casting according to any one of claims 1 to 5. The thermal resistance portion is configured by filling a filler with a predetermined width space,
By adjusting at least one of the width of the space, the type of filler and the filling rate of the filler, the thermal resistance value of the thermal resistance portion is adjusted,
The casting mold for continuous casting according to any one of claims 1 to 6. The continuous casting mold includes an outermost cooling unit that cools the continuous casting mold, an innermost heat-resistant mold that contacts the slab or the mold powder, the heat-resistant mold, and the cooling unit. The heat resistance part that is provided between and suppresses heat transfer between the heat-resistant mold and the cooling part, and
The casting mold for continuous casting according to any one of claims 1 to 7. The continuous casting mold is configured by fitting an auxiliary mold in which the thermal resistance portion is formed in a side wall into a cooling mold for cooling the continuous casting mold.
The casting mold for continuous casting according to any one of claims 1 to 8. A continuous casting method using a continuous casting mold in which molten metal and mold powder are supplied from above, and the slab solidified from the molten metal is drawn from below,
A thermal resistance portion that prevents cooling of the inner surface of the side wall of the continuous casting mold in contact with the slab or the mold powder is provided inside the side wall,
Continuous casting method. The thermal resistance portion is formed for a region having a depth from at least 100 (mm) to 200 (mm) from the hot water surface.
The continuous casting method according to claim 10. Continuous casting is performed without oscillation without vibrating the continuous casting mold,
The continuous casting method according to claim 10 or 11.

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