JP2007222894A - Method of pressing width of hot slab using edging die and die used for the same method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an edging die for hot slabs and a width pressing method by which heavy edging is stably made possible without increasing edging load. <P>SOLUTION: In this width pressing method using the edging die for hot slabs, angles α<SB>1</SB>, α<SB>2</SB>which are formed by the first inclined part and the second inclined part of the die to the advancing direction of the slab and the length L of the intermediate parallel part are set so that the contact length L<SB>0</SB>of the die with the hot slab at the bottom dead center does not exceed the preset contact length L<SB>0</SB><SP>*</SP>on the basis of formula (5) and the rolling reduction w<SB>1</SB>, w<SB>2</SB>by the first inclined part and the second inclined part and the feeding pitch P of the slab between the width pressing passes are set. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a width press using a mold for reducing the width of a hot slab that can stably reduce greatly without increasing the width reduction load in the width reduction of the hot slab by a plate width pressing device. The present invention relates to a method and a mold used in the method.

  As a means for changing the width of the hot slab, the temperature of the slab manufactured by the continuous casting process is not lowered, or after the temperature is once lowered, the slab is heated to a predetermined temperature in a heating furnace. 2. Description of the Related Art A plate width press apparatus that uses a pair of dies installed so as to face each other in the plate width direction of the hot slab to intermittently reduce the hot slab in the plate width direction is used. In the width reduction by this board width press apparatus, the width reduction of about 300-350mm at the maximum is normally performed with respect to the hot slab of the width of about 900-2000mm, and the slab cast to the same width by continuous casting. This makes it possible to manufacture steel plate products with different widths. This has greatly contributed to the productivity improvement and rationalization of the steel sheet manufacturing process, such as reducing the number of width changes in the continuous casting process, expanding schedule-free rolling in the hot rolling process, and increasing the coil weight. The merit increases as the width reduction capability of the plate width press device increases.

  In general, the width reduction load F by the plate width pressing device can be approximately obtained by the equation (1).

F = k · Q _p · h · L ₀ (1)
k is the deformation resistance of the material, Q _p is the rolling force function, h is the slab thickness, and L ₀ is the contact length between the slab and the mold. Increasing the width reduction amount increases the contact length L _0, so the conventional width press method cannot avoid increasing the width press load such as the width reduction load and the width reduction torque, and the power of the reduction motor, flywheel, etc. It is necessary to reinforce the rigidity of devices such as systems, drive systems that transmit power, and housings. From the equation (1), in order to solve the problem of increasing the width reduction load, for example, the feed pitch P (slab transport distance for each pass of the press) is shortened (usually about 350 to 400 mm), or the mold is inclined. It is effective to shorten the contact length L ₀ by increasing the angle. In addition, increasing the width reduction amount also promotes troubles such as buckling and slipping of the slab, so the conventional width reduction mold and width pressing method cannot increase the width reduction amount of the hot slab so much. There was a point. FIG. 9 is a diagram showing a balance of forces in a contact start state of a mold and a slab when the width is reduced by a conventional width reduction mold including a parallel portion and one inclined portion that are conventionally used; In the reduction pass, the contact starts from the mold inclined portion and the slab inclined surface that is reduced by the mold inclined portion in the previous pass. At this time, the condition for preventing the occurrence of slip in the longitudinal direction is that the inclination angle of the mold is α, the coefficient of friction between the mold and the slab is μ, and the contact force at the start of contact is F ₀ . (2) '

μF ₀ cos α ≧ F ₀ sin α (2)
μ ≧ tan α (2) ′
Usually, under the width reduction by the plate width press apparatus, the angle of the inclined portion is about 12 °, and the friction coefficient must be 0.21 or more in order to satisfy the relationship (2) ′. Further, in order to prevent the slab from being twisted not only in the longitudinal direction but also in the thickness direction, a technique has been proposed in which the friction surface of the mold is roughened to adjust the friction coefficient to 0.3 or more (for example, a patent). Reference 1).

  In addition to this, a method for preventing slipping during significant reduction by setting the feed pitch and the inclination angle of the mold has also been proposed (for example, see Patent Document 2). Patent Document 2 is characterized in that the feed pitch or the inclination angle α of the mold is set so as to satisfy the expression (3).

P> ΔW / tan α (3)
ΔW is a width reduction amount (mm) by a mold on one side. Normally, when the width is reduced by a plate width press apparatus, the angle of the inclined portion is about 12 °. For example, when the width reduction amount is 300 mm, the feed pitch P is 706 mm or more in the setting according to the equation (3). Since the mold parallel part starts to contact the unstressed lower part on the side surface of the slab, no slip occurs at the start of width reduction. Further, in Patent Document 2, a second parallel part is formed in the mold inclined part, and in this pass, the part that is squeezed by the second parallel part in the previous pass and the mold parallel part start to contact each other. A method for preventing slippage during width reduction by setting the mold shape and the feed pitch is disclosed.

Moreover, in patent document 3, in order to obtain the method and apparatus which implement | achieves large reduction, preventing buckling of the slab which had arisen in the case of width sizing, by providing two sets of a mold inclination part and a parallel part. A technique for realizing a large width reduction is disclosed, and a 600 mm width reduction example is shown in the embodiment.
JP-A-5-15908, claims, etc. JP-A-9-253780, claims, etc. Japanese Patent Laid-Open No. 3-174902, Claims, Specific Example 1, FIG. 1, etc.

  However, each of the prior arts described above has the following problems.

  First, as a measure for reducing the width reduction load at the time of significant reduction estimated from the equation (1), the method of reducing the contact length between the slab and the mold by shortening the feed pitch P is as follows. Since the time during which the width is reduced to the tail end increases, the productivity is lowered and the temperature of the slab is lowered, so that a desired finishing temperature in hot rolling cannot be secured. In addition, in the method of reducing the contact length between the slab and the mold by increasing the mold inclination angle, the slip at the start of the contact between the mold and the slab is promoted by the relationship of the formula (2) and stable. There is a problem that it is difficult to reduce the width.

  In the method of roughening the die pressing surface disclosed in Patent Document 1 and increasing the coefficient of friction to enable significant reduction, the die pressing surface that accompanies the pressing may be used immediately after the die is replaced. It is difficult to control the change in properties, and in order to keep the coefficient of friction constantly high, it is necessary to change the mold frequently. Due to a decrease in productivity and frequent finish processing of the mold pressure lower surface There was a problem that the mold life was shortened.

The method of setting the feed pitch P or the mold inclination angle α disclosed in Patent Document 2 (3) has various problems even if slippage during drastic reduction can be prevented. First, when adjusting the feed pitch based on the formula (3), for example, if the mold inclination angle α is 12 ° and the width reduction amount W is 300 mm, the feed pitch P must be 706 mm or more, usually 350 to 400 mm. Therefore, it is inevitable that the width reduction load will increase significantly. For this reason, further increase in the width reduction cannot be expected. Further, when the mold inclination angle α is adjusted by the expression (3), for example, when the width reduction amount W is 300 mm and the feed pitch P is 400 mm, the mold inclination angle α needs to be 20.6 ° or more. Become. However, when the mold inclination angle increases, the dogbone formed at the end of the slab due to the width reduction becomes excessive, and the width return due to the subsequent horizontal rolling increases. That is, since the width reduction efficiency η defined by the equation (4) is deteriorated, it is necessary to set a large amount of width reduction necessary to obtain a desired product width, which leads to an increase in width reduction load. There was a problem.

W ₀ is the slab width, W ₁ is the slab width after the width reduction by the sheet width press, and W ₂ is the slab width after one-pass horizontal rolling from the state of W ₁ to the slab thickness before the width reduction. Further, when the dogbone becomes excessive, the number of subsequent horizontal rolling passes must be increased, resulting in a decrease in productivity and a decrease in slab temperature.

  In addition, a second parallel part is formed in the mold inclined part disclosed in Patent Document 2, and in this pass, the part parallel to the second parallel part and the mold parallel part are reduced in the previous pass. In the method of setting the mold shape and feed pitch so as to start contact, the occurrence of slip can be avoided, but no consideration has been given to suppressing an increase in the width reduction load, and the method for determining the shape Does not disclose any guidance.

  Also, in Patent Document 3, no consideration is given for suppressing the increase in the width reduction load, and it is easily assumed from the examples that the width reduction load is greatly increased. It is difficult to apply the described technique to an actual plate width reduction device.

  The present invention has been made in view of the above-described circumstances, and relates to a hot slab width reduction mold and a width press method that can stably and significantly reduce a width without increasing a width reduction load. . In addition, the large reduction by this invention is the width reduction of 350 mm or more which is the width reduction range by the present board width press apparatus.

In order to solve the above-mentioned problems, the present inventors have conducted extensive studies on the width load characteristics and material deformation characteristics at the time of width reduction by a plate width press apparatus, and as a result, the width reduction load is not increased and stably increased. We have conceived a die for width reduction of a hot slab that enables reduction and a width pressing method. As described above, the width reduction load F by the plate width pressing apparatus can be approximately obtained by the equation (1), and the width reduction load is approximately proportional to the contact length L ₀ between the slab and the mold. The relationship between the width press load and the contact length will be described in more detail with reference to FIGS. FIG. 4 is a diagram showing a state at the bottom dead center of a mold by a conventional mold for width reduction consisting of a parallel part and one inclined part, L ₀ is the contact length between the mold and the slab, and ΔW is one side The width reduction amount by the mold and the hatched area indicate the reduction area in the reduction path. FIG. 5 shows the contact length between the mold and the slab and the width reduction when the hot slab having a thickness of 235 mm and a width of 1500 mm is subjected to width reduction under the conditions of a mold inclination angle of 12 ° and a feed pitch of 400 mm. It is a figure which shows an example of the relationship of a load.

As shown in the equation (1), the width reduction load is substantially proportional to the contact length between the mold and the slab, and the width reduction load increases as the width reduction amount increases. However, the relationship shown in FIG. 5 indicates that if the contact length L ₀ between the mold and the slab cannot be increased even during a significant reduction, an increase in the width reduction load can be suppressed. . For this reason, in order to enable stable large reduction without increasing the width reduction load under the width reduction of the hot slab, the contact length L ₀ between the mold and the slab is increased. In addition, the present inventors have found that the mold shape and the feed pitch may be optimally set so that the rolling starts from the parallel portions of the mold and the slab.

  The present invention has been made based on these findings and has the following characteristics.

(1) A width pressing method using a width reduction mold that is installed so as to face relative to the plate width direction of the hot slab and intermittently reduces the hot slab in the plate width direction,
The mold has a mold parallel part parallel to the side surface of the hot slab on the slab surface of the hot slab in the direction of travel, and continuously in the direction of entry of the hot slab in the direction of travel of the hot slab. A first inclined portion that spreads toward the front, an intermediate parallel portion that is continuous with the side of the hot slab in the direction of travel of the hot slab of the first inclined portion and is substantially parallel to the side surface of the hot slab, and a hot slab of the intermediate parallel portion Having a second inclined portion that extends continuously in the direction of entry of the hot slab in the direction of entry of the hot slab continuously to the entry end of the direction of travel;
Based on the following equation (5), the contact length L ₀ between the mold and the hot slab at the rolling bottom dead center should not exceed the preset contact length L ₀ ^* .
The angles α ₁ and α ₂ formed by the first inclined portion and the second inclined portion of the mold with respect to the slab traveling direction, and the length L of the intermediate parallel portion are set.
A hot slab width reduction mold characterized by setting a reduction amount w ₁ , w ₂ by the first inclined portion and the second inclined portion, and a feed pitch P of the slab between the width reduction paths. The width press method used.

However,
L ₀ is the contact length between the mold and the hot slab at the bottom dead center.
L ₀ ^* is a preset contact length, L ₀ ^* ≦ 1350 mm
α ₁ and α ₂ are angles formed by the first inclined portion and the second inclined portion with respect to the slab traveling direction,
w ₁ and w ₂ are respectively the amount of reduction L by the first inclined portion and the second inclined portion, the length of the intermediate parallel portion,
P is the feed pitch of the slab between the width reduction passes.

(2) In the width press method according to (1), in the pass, in the previous pass, a die located on the exit side in the advancing direction of the hot slab and the portion squeezed by the intermediate parallel part of the die inclined part A width pressing method characterized in that the feed pitch is set so that the parallel part starts contact or the unstressed lower side surface of the hot slab starts contact at the intermediate parallel part.

(3) The width pressing method according to (1) or (2) is applied when the width reduction amount on one side is equal to or greater than the reduction amount w ₁ by the first inclined portion of the width reduction mold. Hot slab width pressing method.

(4) A die for width reduction of a hot slab used in the width pressing method according to any one of (1) to (3),
Angular difference between the angle α ₁ formed by the mold parallel part located on the exit side of the hot slab and the first inclined part, and the angle α ₂ formed by the intermediate parallel part and the second inclined part of the mold inclined part Is a die for width reduction of a hot slab characterized by being 5 ° or less.

  According to the die for width reduction of a hot slab and the width pressing method according to the present invention, in the width reduction of the hot slab by the plate width press device, the substantial reduction is stably performed without increasing the width reduction load. It becomes possible to do.

  Hereinafter, embodiments of the present invention will be described.

FIG. 1 is an embodiment showing a width reduction mold according to the present invention, and is a view showing a state at a top dead center when width reduction is performed by a width reduction mold according to the present invention. A first inclined portion that spreads continuously in the direction of entry of the hot slab in the traveling direction and continuous to the mold parallel portion located on the pressure-lower surface on the exit side in the traveling direction of the hot slab, and hot between the first inclined portions An intermediate parallel portion that is continuous to the inlet side end of the slab and substantially parallel to the side surface of the hot slab, and an intermediate parallel portion that is continuous to the inlet side end of the hot slab direction of the intermediate slab and the inlet direction of the hot slab It has the 2nd inclined part which spreads toward. α ₁ and α ₂ are angles formed by the first inclined portion and the second inclined portion with respect to the slab traveling direction, respectively, and w ₁ and w ₂ are respectively the amount of reduction by the first inclined portion and the second inclined portion. is there. Further, L is the length of the intermediate parallel portion, P is the feed pitch of the slab between the width reduction passes, S is the reduction stroke of the mold on one side, and ΔP is the die when the slab is conveyed between the passes. This is a margin to prevent the slab from colliding. Also, FIG. 2 is a diagram illustrating a state at a reduction bottom dead center, [Delta] W is the width reduction amount by the side of the mold, L ₀ is the die and the slab of contact length, L _T is first inclined portion, intermediate parallel portion and the second inclined portion and the contact between the slab length and alpha _a mean tilt angle defined by L _T and ΔW and hatched area, is the area to be reduction in the path. In the present invention, FIG. 1, by optimizing the die configuration according to the present invention shown in FIG. 2, by a contact length L ₀ and equal to or less than the reference contact length L ₀ ^*, a width reduction load It is possible to reduce the width without increasing the width. For this purpose, the following relationship may be established in FIG.

The reference contact length L ₀ ^* may be arbitrarily determined in consideration of the equipment rigidity of each width reduction device. However, the maximum contact length that can be assumed in the conventional mold in the general plate width press apparatus shown in FIG. 4 is the width reduction condition of an inclination angle of 11 °, the maximum width reduction amount: 350 mm, and the feed pitch: 450 mm. 1350 mm. Therefore, the reference contact length L ₀ ^* does not exceed this maximum contact length. In the actual operation of the present invention, referring to the limit width reduction condition by the conventional mold shown in FIG. 4, the contact length between the mold and the slab under the condition is not exceeded from the relationship of the formula (1). It is good. For example, when the conventional mold has an inclination angle of 12 °, a maximum width reduction amount of 350 mm, and a width reduction condition of a feed pitch of 400 mm, the contact length between the mold and the slab at the reduction dead center is 1223 mm. Therefore, under this width reduction condition, when determining the mold shape, L ₀ ^* is set to 1223 mm, and parameters such as α ₁ , α ₂ , w ₁ , w ₂ , and P are set so as to satisfy the equation (5). It is desirable to make a decision. By doing in this way, it is possible to perform a larger drastic reduction with a width reduction load substantially the same as the limit width reduction condition with a conventional mold.

Next, a guideline for determining α ₁ and α ₂ that are angles formed by the first inclined portion and the second inclined portion with respect to the slab traveling direction, and the intermediate parallel portion length L will be described. The inclination angle of the mold greatly affects the width reduction efficiency expressed by the equation (4). FIG. 6 is an example in which the relationship between the mold inclination angle and the width reduction efficiency of a conventional mold is examined, and the width reduction efficiency decreases as the mold inclination angle increases. 7 and 8 are examples of a dogbone shape after width reduction by a conventional mold (width reduction amount 300 mm), FIG. 7 shows a mold inclination angle of 12 °, and FIG. 8 shows a mold inclination angle of 20 °. Is the case. The greater the mold tilt angle, the larger the dogbone, and the peak position of the dogbone height is closer to the plate width end. That is, the effect of width reduction is difficult to reach the center of the sheet width, so that the width return in horizontal rolling is large and the width reduction efficiency is deteriorated. In the die for width reduction according to the present invention, the average inclination angle α _A is defined as shown in FIG. 2, and the relationship between the average inclination angle α _A and the width reduction efficiency is examined. I found it. In order to carry out efficient large reduction, it is important that the width reduction efficiency is 80% or more, and the average inclination angle α _A is preferably about 20 ° or less. In addition, when α ₁ and α ₂ which are angles formed by the first inclined portion and the second inclined portion with respect to the slab traveling direction are greatly different, the dogbone shape is not uniform in the longitudinal direction. Periodic plate width fluctuations corresponding to the feed pitch occur. Usually, after width reduction, automatic sheet width control called AWC (Auto Width Control) is performed by tension control between edging rolls in rough rolling and rolling stands in finish rolling. Even if it occurs, it is not a big problem. However, since the plate width variation of the hot-rolled steel plate greatly affects the yield, it is strictly managed in units of several mm, and it is preferable to control the plate width variation at the time of width reduction as much as possible. As a result of repeated examination of width fluctuation when the width reduction mold according to the present invention is used, it is possible to ensure the same plate width accuracy as a conventional mold by making the difference between α ₁ and α ₂ within about 5 °. I found out. Therefore, in the present invention, it is preferable that the angle difference between the first inclined portion and the second inclined portion with respect to the slab traveling direction is 5 ° or less. Further, the length L of the intermediate parallel portion is desirably long in consideration of the purpose of preventing slip, but in the present invention, the contact length L ₀ between the mold and the slab is defined for the purpose of suppressing the width reduction load. Therefore, in order to increase the length L of the intermediate parallel portion, it is necessary to increase the inclination angle α ₁ of the first inclined portion or the inclination angle α ₂ of the second inclined portion. From the viewpoint of variation, it is not preferable, and considering the width reduction efficiency, slip prevention, feed pitch accuracy, and the like, the contact length L ₀ is preferably about 100 to 200 mm. Further, in order to prevent slip that is likely to occur at the start of contact between the mold and the slab, the contact may be set to start from the parallel portions of the mold and the slab. The part of the mold that has been squeezed by the middle parallel part of the mold and the mold parallel part that is located on the squeezing surface on the exit side of the hot slab in the pass start contact or the hot slab has not been It is determined that the mold parallel part starts to contact at the intermediate part of the inferior side and the mold inclined part, but conversely the feed pitch is known and the above α ₁ , α ₂ , L _0, etc. It is also possible to determine the parameters.

Another object of the present invention is to enable stable and significant reduction without increasing the width reduction load. When the width reduction amount is smaller than w ₁ , the effect is not exhibited. For this reason, a width reduction mold according to the present invention and a conventional mold are prepared, and the width reduction amount on one side is the reduction amount w ₁ by the first inclined portion of the width reduction mold according to the present invention. In the above case, the present invention is applied, and if it is smaller than w1, it is desirable to use a conventional width reduction die.

Examples of the present invention will be described below. Using a sheet width press apparatus, sheet width reduction was performed on a normal steel slab having a thickness of 235 mm, a width of 1500 mm, and a heating temperature of 1200 ° C. under the conditions of (a) to (g) at a width reduction cycle of 50 times per minute. In the design of the die for width reduction according to the present invention in (D) to (G), the feed pitch P is fixed to 400 mm, and L ₀ ^* is the contact length between the die and the slab under the condition (A). The mold shape was determined.

  (A) Comparative example 1 is the conventional width reduction by the conventional mold of FIG. 4, and the width reduction is performed under the conditions of the inclination angle α = 12 °, the width reduction amount = 2 × ΔW = 350 mm, and the feed pitch P = 400 mm. Carried out.

  (B) Comparative Example 2 is a significant reduction by the conventional mold shown in FIG. 4, and the width reduction is performed under the conditions of the inclination angle α = 12 °, the width reduction amount = 2 × ΔW = 400 mm, and the feed pitch P = 400 mm. did.

  (C) Comparative Example 3 is a significant reduction by the conventional mold of FIG. 4, and the width reduction is performed under the conditions of the inclination angle α = 12 °, the width reduction amount = 2 × ΔW = 450 mm, and the feed pitch P = 400 mm. did.

(D) In Example 1, the contact length L ₀ (= 1223 mm) between the mold and the slab in Comparative Example 1 is the same, and α ₁ = The width reduction was performed under the conditions of 18 °, α ₂ = 16 °, w ₁ = 107 mm, L = 170 mm, width reduction amount = 2 × ΔW = 400 mm, and feed pitch P = 400 mm.

(E) Example 2, Comparative Examples mold in one and contacting the slub length L ₀ (= 1223mm) and and a contact length is the same, in order to examine the influence of the width variation after horizontal rolling, alpha ₁ = 14 °, α ₂ = 20 °, w ₁ = 82 mm, L = 170 mm, width reduction was performed under the conditions of width reduction amount = 2 × ΔW = 400 mm and feed pitch P = 400 mm.

(F) Example 3, Comparative Example 1 mold and the contact length of the slab in L ₀ (= 1223mm) and and a contact length is the same, in order to examine the influence of the width variation after horizontal rolling, alpha ₁ = 14 °, α ₂ = 19 °, w ₁ = 119 mm, L = 153 mm, width reduction was performed under the conditions of width reduction amount = 2 × ΔW = 400 mm and feed pitch P = 400 mm.

(G) In Example 4, the contact length L ₀ (= 1223 mm) of the mold and the slab in Comparative Example 1 is the same as that of the _first embodiment, and α ₁ = 19 °, The width reduction was performed under the conditions of α ₂ = 18 °, w ₁ = 120 mm, L = 170 mm, width reduction amount = 2 × ΔW = 450 mm, and feed pitch P = 400 mm.

  FIG. 3 compares the transition of the width reduction load for one pass in the vicinity of the center portion in the longitudinal direction of the slab under the conditions of Comparative Example 1 and Examples 1 to 4. Although the timing at which the width reduction load rises varies with the increase in the width reduction amount, the maximum width reduction load in the vicinity of the reduction dead center is substantially the same. Table 1 shows each condition, the maximum width reduction load, and the width fluctuation amount after horizontal rolling in the steady deformation portion in the vicinity of the slab longitudinal center. The width reduction load when the width reduction mold according to the present invention is used is about 5% increase in load even in the condition of Example 4 where the amount of width reduction is the largest as compared with Comparative Example 1 which is the reference condition. This is because the mold shape is designed so that the contact length between the mold and the slab is the same under each condition, but the deformation resistance increases due to work hardening of the material as the width reduction amount increases. It is also possible to design a mold shape in consideration of the work hardening of this material in advance. Compared with the case where the width reduction amount is increased by the conventional mold, the width reduction amount is 400 mm, the width reduction amount is about 10% in the first to third embodiments compared to the comparative example 2, and the width reduction amount is 450 mm. Compared to Comparative Example 3, the width reduction load is reduced by about 17% in Example 4. From these results, it was confirmed that when the width reduction mold according to the present invention was used, the width reduction load was hardly increased and a large reduction could be realized stably. Further, in the conditions of this example, since the mold and the slab always start contact from parallel parts, no trouble such as slip occurred, whereas in Comparative Examples 2 and 3, the occurrence of irregular slips occurred. Was observed, and the width reduction load in each pass was not stable.

Moreover, even if the contact length of a metal mold | die and a slab is the same from Example 1-3, in Example 2 with large (alpha) ₁ and (alpha) ₂ difference of 6 degrees, the horizontal rolling mill rear surface after width reduction The width fluctuation amount measured with a plate width meter installed in was slightly increased to 15 mm. From these experimental results, it can be seen that the difference between α ₁ and α ₂ is preferably 5 ° or less.

The figure which shows the shape of the metal for drastic reduction by this invention. The figure which shows the condition in the reduction dead center in the metal for large reductions by this invention. The figure which shows transition of the width reduction load at the time of the large reduction by the conventional metal mold | die compared with the metal mold | die for large reduction by this invention. The figure which shows the condition in the rolling down dead center with the conventional metal mold | die. The figure which shows the relationship between the width reduction amount by the conventional metal mold | die, the contact length of a metal mold | die and a slab, and the width press load. The figure which shows the relationship between a metal mold | die inclination angle and the width reduction efficiency at the time of the width reduction in the conventional metal mold | die. The figure which shows an example of the dog-bone shape produced | generated by the width reduction in the conventional metal mold | die (metal mold inclination angle 12 degrees). The figure which shows another example of the dogbone shape produced | generated by the width reduction in the conventional metal mold | die (die inclination | tilt angle of 20 degrees). The figure which shows the condition in the rolling down dead center in the conventional metal mold | die.

Claims (4)

It is a width pressing method using a mold for width reduction that is installed relative to the plate width direction of the hot slab and intermittently reduces the hot slab in the plate width direction,
The mold has a mold parallel part parallel to the side surface of the hot slab on the slab surface of the hot slab in the direction of travel, and continuously in the direction of entry of the hot slab in the direction of travel of the hot slab. A first inclined portion that spreads toward the front, an intermediate parallel portion that is continuous with the side of the hot slab in the direction of travel of the hot slab of the first inclined portion and is substantially parallel to the side surface of the hot slab, and a hot slab of the intermediate parallel portion Having a second inclined portion that extends continuously in the direction of entry of the hot slab in the direction of entry of the hot slab continuously to the entry end of the direction of travel;
Based on the following equation (5), the contact length L ₀ between the mold and the hot slab at the rolling bottom dead center should not exceed the preset contact length L ₀ ^* .
The angles α ₁ and α ₂ formed by the first inclined portion and the second inclined portion of the mold with respect to the slab traveling direction, and the length L of the intermediate parallel portion are set.
A hot slab width reduction mold characterized by setting a reduction amount w ₁ , w ₂ by the first inclined portion and the second inclined portion, and a feed pitch P of the slab between the width reduction paths. The width press method used.

However,
L ₀ is the contact length between the mold and the hot slab at the bottom dead center.
L ₀ ^* is a preset contact length, L ₀ ^* ≦ 1350 mm
α ₁ and α ₂ are angles formed by the first inclined portion and the second inclined portion with respect to the slab traveling direction,
w ₁ and w ₂ are respectively the amount of reduction L by the first inclined portion and the second inclined portion, the length of the intermediate parallel portion,
P is the feed pitch of the slab between the width reduction passes.   In the width press method according to claim 1, in the pass, in the previous pass, a portion that is squeezed by an intermediate parallel portion of the die inclined portion and a die parallel portion that is located on the exit side in the traveling direction of the hot slab are provided. A width pressing method characterized in that a feed pitch is set so as to start contact, or so that an unpressed lower side surface of a hot slab starts contact at an intermediate parallel portion. The width of the hot slab, wherein the width pressing method according to claim 1 or 2 is applied when the width reduction amount on one side is equal to or greater than the reduction amount w ₁ by the first inclined portion of the width reduction mold. Press method. A die for width reduction of a hot slab used in the width pressing method according to claim 1,
Angular difference between the angle α ₁ formed by the mold parallel part located on the exit side of the hot slab and the first inclined part, and the angle α ₂ formed by the intermediate parallel part and the second inclined part of the mold inclined part A die for width reduction of a hot slab, characterized in that is 5 ° or less.

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