JP5141282B2 - Width reduction mold for hot slab and width reduction method - Google Patents

Description

  TECHNICAL FIELD The present invention relates to a hot slab width reduction mold and a width reduction method that can stably perform width reduction by preventing slipping in the width reduction of a hot slab by a width press device (width reduction device). It is.

  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 plate width press apparatus, the width reduction of about 300 to 350 mm at maximum is usually performed on the hot slab of about 900 to 2000 mm, 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.

  However, if the amount of width reduction is increased with a conventional mold having only one inclined portion (hereinafter referred to as a flat die), the lower portion of the mold will be reduced in the previous pass. Since the contact is started from the inclined surface of the slab and the inclined portion of the mold, the phenomenon that the slab slips at the time of reduction occurs under the condition that the friction coefficient is small, and the conventional width reduction mold and width reduction method However, there was a problem that the width reduction amount of the hot slab could not be increased so much. Note that the friction coefficient between the mold and the slab is greatly influenced by the state of the oxide scale and the mold surface depending on the steel type and heating temperature, so the friction coefficient is constantly kept high to prevent slipping. It is difficult to do.

  For this reason, a method for preventing slipping during a significant reduction by setting the mold shape and the feed pitch has been proposed (for example, see Patent Documents 1 and 2).

  That is, Patent Document 1 is characterized in that the feed pitch P or the mold inclination angle α is set so as to satisfy the following expression.

P> ΔW / (2 · tan α)
Here, ΔW is a width reduction amount (mm) by a mold on one side. Normally, when the width is reduced by the plate width press apparatus, the inclination angle α of the inclined portion is about 12 °. For example, if the amount of width reduction is 300 mm, the feed pitch P is 706 mm or more in the setting according to the above equation. Since the mold parallel part starts contact with the unpressed lower part on the side surface of the slab, no slip occurs at the start of width reduction.

  Moreover, in patent document 1, an intermediate | middle parallel part (2nd parallel part) is formed in the middle of a metal mold | die inclination part, a metal mold | die inclination part is divided into a 1st inclination part and a 2nd inclination part, and the said path | pass Then, by setting the mold shape and the feed pitch so that the portion pressed by the second parallel part and the mold parallel part (first parallel part) in the previous pass start contact, the width A method for preventing slippage during rolling is disclosed. Hereinafter, a mold shape having a first inclined part and a second inclined part is referred to as a two-stage mold.

And in patent document 2, similarly, regarding the shape of the two-stage mold used from the viewpoint of slip prevention, a method of defining the contact length between the mold and the material at the bottom dead center to be a predetermined length or less from the viewpoint of the width reduction load. Has been proposed.
JP-A-9-253780 JP 2007-222894 A

  However, the above-described conventional techniques (Patent Documents 1 and 2) relating to slip prevention at the time of width reduction have a large problem from the viewpoint of sheet feeding stability at the time of width reduction.

  First, in the technique for adjusting the feed pitch disclosed in Patent Document 1, for example, when 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. Since it becomes about twice the feed pitch set to 350 to 400 mm, a significant increase in the width reduction load is inevitable. For this reason, the width reduction amount is limited, and reduction of the merit obtained by the above-described large reduction is inevitable.

  In addition, the conventional two-stage mold has a great effect in preventing slipping when the ideal width reduction condition is satisfied, but the dogbone height generated by the width reduction is likely to be uneven in the traveling direction. Because the uneven shape is formed in the direction of travel at the feed pitch cycle, the uneven dogbone hits the pinch roll and transport roll, causing slippage due to difficulty in feeding between passes at a predetermined pitch It has become. In order to explain this, FIGS. 10 and 11 schematically show the cross-sectional shape of the uneven portion of the dogbone in the traveling direction. The difference between the convex dogbone height H1 and the concave dogbone height H2 is hereinafter referred to as the dogbone unevenness amount. Normally, as shown in FIG. 12, the width press apparatus includes upper and lower pinch rolls 9, 9 ′, 10, 10 ′ and inlet / outlet transport rollers 7, 8 at the front and rear positions of the mold 12 that performs the width reduction. And is used to transport the slab 13 between the rolling passes. As the pinch roll type, the slab is narrowed by the upper and lower drive pinch rolls and the dogbone is lightly pressed while intermittently moving at a predetermined feed pitch, and the upper pinch roll is not driven and the lower is the drive roll. There is a type in which a slab is pressed against a pinch roll to ensure frictional force and feed the slab between passes. In any type of pinch roll device, when the dog bone becomes large, the dog bone hits the pinch rolls 10 and 10 ′ during conveyance, resulting in poor progress, and it becomes difficult to secure a predetermined feed pitch between the reduction passes. In addition, 11 and 11 'in FIG. 12 are the upper and lower buckling prevention rolls.

In the prior art described above, as shown in FIG. 5, in the reduction pass, the die shape and the feed pitch f are set so that the portion parallel to the die parallel portion and the die parallel portion started to contact in the pre-reduction pass. Is set to prevent slipping when the width is reduced. However, when the feed pitch p is smaller than a predetermined value f due to poor progress (p <f), as shown in FIG. The portion that is crushed by the first inclined portion in the pass also starts to contact the first inclined portion in the crushed pass. If it does so, it has the problem that the slip prevention effect in a two-stage metal mold | die cannot be exhibited.

  The present invention has been made in view of the circumstances as described above, and in the width reduction of the hot slab by the width press device (width reduction device), the heat that prevents the slip and enables the width reduction stably. It is an object of the present invention to provide a mold for width reduction of an intermediate slab and a width reduction method.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies on the mold shape and width reduction conditions for preventing slippage in the plate width press apparatus, and as a result, the dogbone unevenness caused by the two-stage mold is caused. The mold shape and width reduction conditions were found to improve the deterioration of the plate-passability. That is, as will be described in detail later, the mechanism for generating the unevenness of the dogbone by the two-stage mold is such that, in the reduction pass, the portion that has been reduced by the intermediate parallel portion in the pre-reduction pass and the mold parallel portion start to contact each other. It has been found that this is due to the basic idea itself of the conventional two-stage mold, in which the mold shape and feed pitch are set to prevent slipping.

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

[1] A mold for width reduction that is installed so as to face the plate width direction of the hot slab and intermittently reduces the hot slab in the plate width direction.
There is 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 it is continuous with the mold parallel part in a straight line toward the entrance direction of the hot slab. a first inclined portion extending a first intermediate parallel portion substantially parallel to the first aspect of the continuously hot slab in the traveling direction of the entry side end of the hot slab of the inclined portion, a first intermediate parallel A second sloping portion extending in a straight line toward the entering direction of the hot slab in the direction of entering the hot slab in the hot slab running direction of the portion, and the entering direction of the hot slab of the second sloping portion A second intermediate parallel portion that is continuous to the side end and substantially parallel to the side surface of the hot slab, and a hot slab in the direction of hot slab continuous entry to the end of the second intermediate parallel portion in the direction of hot slab progression A third inclined portion that extends in a straight line toward the direction,
In the reduction pass, when the slab is transported at a preset slab feed pitch, the contact starts from the area and the mold parallel part that are reduced by the second intermediate parallel part in the previous reduction pass, When the slab is transported at 1/2 of the preset slab feed pitch, the contact is started from the area that is squeezed by the second intermediate parallel part and the first intermediate parallel part in the pre-pressing pass. When the slab is transported at 1/3 of a preset slab feed pitch, the metal that starts contact from the area parallel to the first intermediate parallel part and the mold parallel part in the pre-reduction path A hot slab width reduction mold characterized by a mold shape .

[2] When the inclination angle of the first inclined portion is α1, the height of the first inclined portion is w1, and the preset feed pitch is f,
1/3 × f> w1 / tanα1
The hot rolling slab width reduction mold according to [1], wherein the relationship is satisfied .

  [3] A hot slab width reduction method, wherein the hot slab width reduction is performed using the hot slab width reduction mold according to [1] or [2].

  In the present invention, when performing the width reduction of the hot slab, it is possible to prevent slipping and achieve stable width reduction.

As shown in FIG. 5, the two-stage mold used for the hot slab width reduction generally has a mold parallel part 3 ′ parallel to the side surface of the hot slab 13 on the pressing surface on the exit side in the traveling direction. The first inclined portion 1 ′ which spreads continuously at the inclination angle α ₁ toward the direction of entering the hot slab 13 in succession to the mold parallel portion 3 ′ and the first inclined portion 1 ′ An intermediate parallel portion 4 ′ that is continuous to the side of the hot slab 13 and continuous to the end of the slab 13 in the direction of travel, and a heat that is continuous to the side of the intermediate slab 13 in the direction of travel of the hot slab 13 It has 2nd inclination part 2 'which spreads by inclination-angle (alpha) ₂ toward the advancing direction entrance side direction of the intermediate | middle slab 13. As shown in FIG.

  In the prior art, the slab 13 is prevented from slipping in the advancing direction by applying the mold parallel part 3 ′ to the surface that has been squeezed by the mold intermediate parallel part 4 ′ in the pre-reduction path. However, as described above, in this conventional technique, since the dogbone has a non-uniform uneven shape in the longitudinal direction, the mechanism will be described in detail.

Although the actual material flow inside the slab is complicated, in the prior art, as schematically shown in FIG. 9, a region A ′ squeezed by the mold parallel part 3 ′ and a region C squeezed by the intermediate parallel part 4 ′. In ', the material flows in the rolling direction, but in the region B' that is rolled down by the first inclined portion 1 'and the region D' that is rolled down by the second inclined portion 2 ', the materials are inclined at angles α ₁ and α ₂ , respectively. Will flow in a substantially vertical direction. Therefore, in the regions A ′ and C ′, the material tries to flow only in the rolling direction, but in the regions B ′ and D ′, the material also flows in the traveling direction. It will be restrained slightly at B ′ and D ′. Since the volume change does not occur in plastic deformation, if the flow in the rolling direction is restricted, the corresponding volume will flow in the direction of travel and the plate thickness direction. Therefore, since the material hardly flows in the traveling direction, the material greatly flows in the thickness direction where the end portion is a free surface. That is, in the regions A ′ and C ′, it is inevitable that the height of the dogbone is increased by increasing the flow in the plate thickness direction as compared with the regions B ′ and D ′. In addition, in the conventional technique, the region C ′ that has been reduced by the intermediate parallel part 4 ′ in the reduction path is reduced by the mold parallel part 3 ′ in the next reduction path. The dogbone is even higher. That is, in the prior art, in order to prevent slipping, the feed pitch f, the first inclined portion angle α ₁ , and the height w of the first inclined portion so as to start the reduction between the parallel portions of the mold 30 and the slab 13. _In fact, this relationship itself is the cause of expanding the irregularities in the direction of travel of the dogbone. And the unevenness | corrugation of the dogbone of this advancing direction causes a conveyance defect by striking to the conveyance roll 8 or the pinch rolls 10 and 10 ', As a result, it will become a width reduction form like FIG. This is a major cause of slip.

  As a result of intensive studies to solve the conveyance failure under the width pressure caused by the conventional two-stage mold 30, the present inventors have newly added a first inclined portion 1 ′ of the conventional two-stage mold 30. By using a three-stage die with a pair of inclined and parallel parts, the unevenness in the direction of travel of the dogbone is reduced, and the rolling path is reduced by being stuck to the transport roll 8 or the pinch rolls 10 and 10 '. It has been found that even when the feed pitch during the time becomes unstable, the occurrence of slip can be surely prevented in the reduction path.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 4, the mold 20 for width reduction in this embodiment has the mold parallel part 4 parallel to the side surface of the hot slab 13 on the pressing surface on the exit side in the traveling direction, and this mold parallel part. 4 in the direction of entry of the hot slab 13 in the direction of the entrance side of the hot slab 13, the first inclined part 1 spreading at an inclination angle α ₁ , The first intermediate parallel portion 5 that is continuously substantially parallel to the side surface of the hot slab 13 and the hot slab 13 that is continuously in the direction of travel of the first intermediate parallel portion 5 in the direction of travel of the hot slab 13. a second inclined portion 2 extending at an inclination angle alpha ₂ in the direction inlet side direction, substantially continuously in the traveling direction of the entry side end of the second inclined portion 2 of the hot slab 13 to the side surface of the hot slab 13 Progression of the hot slab 13 in succession to the parallel second intermediate parallel part 6 and the entry end of the second intermediate parallel part 6 in the direction of travel of the hot slab 13 Toward the MukoIri side direction and has a third inclined portion 3 extending at an inclination angle alpha _3.

  1 to 3 are views showing a point in time when the mold 20 and the slab 13 start to contact when the width reduction mold 20 according to this embodiment is used, and FIG. 1 shows the slab 13 between the reduction passes. Is the case where the vehicle travels in the traveling direction at the set feed pitch (set distance) f (that is, the travel amount p = the set distance f). On the other hand, FIG. 2 shows that the progress amount p of the slab 13 between the reduction passes is approximately ½ of the set distance f due to a conveyance failure, and FIG. 3 shows that the advance amount p of the slab 13 between the reduction passes is about the set distance f. The case where it was 1/3 is shown.

  In FIG. 1, since the reduction starts from the part parallel to the traveling direction and the mold parallel part 4, which is reduced by the second intermediate parallel part 6 in the pre-reduction path, the mold 20 and the slab are reduced during the reduction. 13 slip does not occur. In FIG. 2, the feed amount p is small due to the conveyance failure of the slab 13 between the reduction passes, but the portion parallel to the traveling direction that is reduced by the second intermediate parallel portion 6 in the front reduction pass and the first portion. Since the reduction starts from the intermediate parallel part 1 of 1, the slip of the mold 20 and the slab 13 does not occur during the reduction. Similarly, in FIG. 3, the feed amount p is reduced due to the conveyance failure of the slab 13 between the reduction passes, but the portion parallel to the traveling direction that is reduced by the first intermediate parallel portion 5 in the previous reduction pass. Since the reduction is started from the mold parallel part 4, no slip of the mold 20 and the slab 13 occurs during the reduction.

  As described above, in the width reduction mold 20 according to this embodiment, even when the feed amount p becomes small due to the conveyance failure of the slab 13 between the reduction passes, the first intermediate parallel portion 5 in the pre-reduction pass. Alternatively, contact starts at the portion parallel to the traveling direction crushed by the second intermediate parallel portion 6 and the mold parallel portion 4, the first intermediate parallel portion 5, or the second intermediate parallel portion 6. The slip between the mold 20 and the slab 13 can be remarkably prevented.

  In addition, in order to exhibit the above-described action when the conveyance amount p of the slab 13 between the reduction passes is reduced due to a conveyance failure, the length of the first inclined portion 1 in the traveling direction is shortened. It is necessary to make it slightly smaller than the amount p.

FIG. 7 shows the relationship between the height (first inclined portion reduction amount) w ₁ of the first inclined portion 1 of the mold 20 and the length in the traveling direction (first inclined portion length = w ₁ / tan α ₁ ). For example, as illustrated in the figure, assuming that the slab conveyance amount p between the reduction passes is about 100 mm, the first inclined portion height w ₁ may be about 30 mm. The height of the second inclined portion 2 is set at a predetermined slab feed pitch. In the reduction pass, the portion that has been reduced by the second intermediate parallel portion 6 in the pre-reduction pass and the mold parallel portion 4 start to contact each other. You just decide to do it.

  Further, in the width reduction mold 20 according to this embodiment, the length of each intermediate parallel part and the inclined part can be shortened as compared with the conventional two-stage mold 30, so as shown in FIG. Since the reduction regions B to D in each part are reduced, the unevenness amount of the dogbone height in the traveling direction, which is a problem with the conventional two-stage mold 30, is significantly reduced.

  Therefore, in the width reduction mold 20 according to this embodiment, the transportability of the slab 13 between the reduction paths is reduced by reducing the unevenness of the dogbone in the traveling direction, which was a problem in the conventional two-stage mold 30. In the case where the slab 13 progresses poorly between the reduction passes and the slab 13 progresses poorly, the progress that has been reduced by the first intermediate parallel portion 5 or the second intermediate parallel portion 6 in the pre-reduction pass. The contact between the part parallel to the direction and the mold parallel part 4 or the first intermediate parallel part 5 or the second intermediate parallel part 6 starts, so that the slip between the mold 20 and the slab 13 is marked. It is possible to prevent and improve the stability under the width pressure by the width press apparatus comprehensively.

Examples of the present invention will be described below. Here, using a width press device, a normal steel slab having a thickness of 235 mm, a width of 1500 mm, and a length of 9000 mm is set to a set feed pitch of 400 mm, a heating temperature of 1200 ° C., and a width reduction cycle of 50 times per minute. ) The width reduction was performed under the conditions. Note that the width reduction amount W is all 350 mm.

  (A) Example 1 is a result of width reduction by the mold A for width reduction according to the present invention, and width reduction was performed without applying a lubricant to the mold.

  (B) Example 2 is a result of width reduction by the width reduction mold A according to the present invention. A lubricant (a grease-based hot lubricant) is applied to the lower surface of the mold between the reduction passes. A width reduction was performed.

  (C) Comparative Example 1 is a result of width reduction by the conventional two-stage mold B. The width reduction was performed without applying a lubricant to the mold.

  (D) Comparative Example 2 is the result of width reduction by the conventional two-stage mold B, and the width reduction is performed by applying a lubricant (grease-based hot lubricant) on the lower surface of the mold between the reduction passes. Carried out.

  Table 1 is a table showing the results of width reduction under the conditions (a) to (d).

  In Examples 1 and 2 using the mold A which is a mold for width reduction according to the present invention, the width reduction occurs as compared with Comparative Examples 1 and 2 using a mold B which is a conventional two-stage mold. The unevenness of the dogbone in the traveling direction is halved. Further, in Examples 1 and 2, the slab conveyance between the reduction passes is stable regardless of whether or not the lubricant is used, and particularly in Example 1 between the mold and the slab before the end of the width reduction of the entire length of the slab. There was no slip. Further, in Example 2 using the lubricant, although the progress failure occurred only once in the vicinity of the slab tail end portion, the slip between the mold and the slab did not occur.

  On the other hand, in the case of the mold B, which is a conventional two-stage mold, even in the case of Comparative Example 1 in which no lubricant is used, the dogbone has a large amount of unevenness in the advancing direction. Advancing failure occurred on the side of the transport roll, and 6 extra passes were required to complete the width reduction of the entire slab as compared with Examples 1 and 2. Further, in the case of Comparative Example 2 in which a lubricant is used in the conventional two-stage mold, first, after a progress failure occurs due to the dogbone unevenness in the traveling direction, a slip between the mold and the slab occurs continuously, I had to stop the reduction.

  As described above, according to the present invention, the amount of unevenness of the dogbone in the traveling direction that occurs in the width reduction is reduced, the conveyance is stabilized, and even when a poor progress of the slab between the reduction passes occurs. Very stable plate width reduction was possible.

It is a figure which shows the reduction condition in the metal mold | die for width reduction by one Embodiment of this invention. It is a figure which shows the reduction condition in the metal mold | die for width reduction by one Embodiment of this invention, and is a figure which shows the condition where the feed amount between reduction paths is about 1/2 of a setting value. It is a figure which shows the reduction condition in the metal mold | die for width reduction by one Embodiment of this invention, and is a figure which shows the condition where the feed amount between reduction paths is about 1/3 of a setting value. It is a figure explaining the shape of the metal mold | die for width reduction by one Embodiment of this invention. It is a figure which shows the condition in the rolling reduction | decrease start point by the conventional two-stage metal mold | die. It is a figure which shows the condition when a feed pitch becomes short in the conventional 2 step metal mold | die. The height of the first inclined portion w ₁ and is a diagram showing the length of the relationship between the first inclined portion. It is a schematic diagram which shows the area | region rolled down in each part of the metal mold | die for width reduction by one Embodiment of this invention. It is a schematic diagram which shows the area | region rolled down by each part of the conventional 2 step metal mold | die. It is a schematic diagram showing the cross-sectional shape of the dogbone convex part of the advancing direction at the time of width reduction with the conventional two-stage metal mold | die. It is a schematic diagram showing the cross-sectional shape of the dogbone recessed part of the advancing direction at the time of width reduction with the conventional 2 step metal mold | die. It is a schematic diagram which shows arrangement | positioning of the various rolls of a width press apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 1st inclination part of the mold for width reduction (three-stage metal mold | die) by one Embodiment of this invention 2 2nd inclination part of the mold for width reduction (three-stage metal mold | die) by one Embodiment of this invention Third inclined portion of width reduction mold (three-stage mold) according to one embodiment of the invention 4 Mold parallel part of width reduction mold (three-stage mold) according to one embodiment of the present invention 5 First intermediate parallel part of width reduction mold (three-stage mold) according to one embodiment 6 Second intermediate parallel part of width reduction mold (three-stage mold) according to one embodiment of the present invention 1 ′ First inclined part of two-stage mold 2 ′ Second inclined part of two-stage mold 3 ′ Mold parallel part of two-stage mold 4 ′ Intermediate parallel part of two-stage mold 7 Entrance conveyance roll of width press device 8 Outlet side conveyance roll of width press apparatus 9 Incoming upper pinch roll of width press apparatus 9 'Incoming lower pinch roll of width press apparatus 10 Outlet upper pinch roll of width press apparatus 10' width Lower pinch roll on the exit side of the pressing device 11 Upper buckling prevention roll 11 'of the width pressing device 11' Lower buckling prevention roll of the width pressing device 12 Mold of the width pressing device 13 Slab 20 Mold for width reduction according to an embodiment of the present invention (3-stage mold)
30 Two-stage mold

Claims (3)

It is a mold for width reduction that is installed so as to face the plate width direction of the hot slab and intermittently rolls down the hot slab in the plate width direction,
There is 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 it is continuous with the mold parallel part in a straight line toward the entrance direction of the hot slab. a first inclined portion extending a first intermediate parallel portion substantially parallel to the first aspect of the continuously hot slab in the traveling direction of the entry side end of the hot slab of the inclined portion, a first intermediate parallel A second sloping portion extending in a straight line toward the entering direction of the hot slab in the direction of entering the hot slab in the hot slab running direction of the portion, and the entering direction of the hot slab of the second sloping portion A second intermediate parallel portion that is continuous to the side end and substantially parallel to the side surface of the hot slab, and a hot slab in the direction of hot slab continuous entry to the end of the second intermediate parallel portion in the direction of hot slab progression A third inclined portion that extends in a straight line toward the direction,
In the reduction pass, when the slab is transported at a preset slab feed pitch, the contact starts from the area and the mold parallel part that are reduced by the second intermediate parallel part in the previous reduction pass , When the slab is transported at 1/2 of the preset slab feed pitch, the contact is started from the area that is squeezed by the second intermediate parallel part and the first intermediate parallel part in the pre-pressing pass. When the slab is transported at 1/3 of a preset slab feed pitch, the metal that starts contact from the area parallel to the first intermediate parallel part and the mold parallel part in the pre-reduction path A hot slab width reduction mold characterized by a mold shape . When the inclination angle of the first inclined portion is α1, the height of the first inclined portion is w1, and the preset feed pitch is f,
1/3 × f> w1 / tanα1
The width reduction die for hot slabs according to claim 1, wherein the relationship is satisfied.   A method for reducing the width of a hot slab, wherein the width of the hot slab is reduced using the mold for reducing the width of a hot slab according to claim 1.

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