JP6915595B2 - How to reduce the width of the slab - Google Patents

Description

The present invention relates to a method for reducing the width of a slab.

Generally, in a hot-rolled steel sheet production line (hot strip mill), a heated slab undergoes a manufacturing process such as a rough rolling process and a finish rolling process to produce a steel sheet having a predetermined plate width and thickness.
In the rough rolling step, horizontal rolling in which the slab is rolled to a predetermined thickness, width rolling in which the slab is reduced in the width direction (width reduction) before horizontal rolling, and the like are performed. In the width reduction press, the slab is conveyed in the longitudinal direction while intermittently forging the slab with the pair of dies using a sizing press having a pair of dies arranged in the width direction of the slab. Width reduction is performed over the longitudinal direction of the. Further, the amount of movement of the slab when the slab is conveyed for each width reduction is referred to as a transfer amount.

Since the sizing press transports the slab while intermittently forging the slab, it is inefficient compared to other processes such as rough rolling and finish rolling, and often reduces the efficiency of the entire hot-rolled steel sheet production line. .. Therefore, various techniques have been studied to improve the efficiency of the sizing press.
For example, in Patent Document 1, the torque generated in the crankshaft for moving the die during width reduction is predicted, and the width reduction speed is set so that the crankshaft has the maximum allowable torque. Methods for improving efficiency are disclosed.
Further, in Patent Document 2, attention is paid to the thickening behavior when the width is rolled down, and since the thickness of the tail end portion is smaller when the width is rolled down, the step following the sizing press is performed. In rolling, a method is disclosed in which the number of passes due to rough rolling is reduced and the efficiency of the entire rough rolling process is improved by engaging the rolling mill from the tail end side.

Japanese Unexamined Patent Publication No. 2006-231364 Japanese Unexamined Patent Publication No. 11-285701

However, with the method disclosed in Patent Document 1, the rotation speed can be increased only according to the torque allowable limit of the crankshaft, and the limit of the efficiency improving effect is determined according to the equipment specifications.
Further, in the method disclosed in Patent Document 2, it is necessary to rotate the slab in order to set the biting end of rolling to the tail end side at the time of sizing press. Further, it becomes necessary to carry out width reduction while transporting the slab from the front side to the rear side. Therefore, the method disclosed in Patent Document 2 has a problem that a time loss occurs.

Therefore, the present invention has been made focusing on the above-mentioned problems, and an object of the present invention is to provide a method for reducing the width of a slab, which can improve the efficiency when the entire length of the slab is reduced by a sizing press. It is said.

According to one aspect of the present invention, in the method of reducing the width of a slab by intermittent forging using a pair of dies, the slabs arranged between the pair of dies are conveyed in a transport direction. The pair of dies are provided with a transport step of transporting only the transport amount D and a width reduction step of reducing the width of the transported slab by moving the pair of dies in the plate width direction of the slab. As a mold, a parallel portion parallel to the end face of the slab and a rear side in the transport direction are provided on the front side in the transport direction so that the rear side in the transport direction spreads in the plate width direction. A mold having an inclined portion is used, and the value of half the width reduction amount of the slab by the pair of dies is the amount of movement of the pair of dies in the plate width direction in the width process. Provided is a method for reducing the width of a slab, which is less than a die stroke and the transfer amount D satisfies the following equation (1).
S / tan θ ≦ D ≦ L1 ・ ・ ・ (1)
S: Mold stroke (m)
θ: Inclination angle (°) of the inclined part
L1: Length of parallel part (m)

According to one aspect of the present invention, it is possible to provide a method for reducing the width of a slab, which can improve the efficiency when the entire length of the slab is reduced by a sizing press.

It is a top view which shows the sizing press in one Embodiment of this invention. It is a top view which shows the state immediately before the width reduction process in the case where the transport amount D becomes L1 or more. It is explanatory drawing which shows the transfer process and width reduction process under the condition that the value of half of the width reduction amount of a slab is equal to or more than the die stroke of a mold. It is explanatory drawing which shows the transfer process and width reduction process under the condition that the value of half of the width reduction amount of a slab is less than the mold stroke of a mold. It is a top view which shows the state immediately before the width reduction process in the width reduction method which concerns on this embodiment.

The following detailed description illustrates many specific details by exemplifying embodiments of the invention to provide a complete understanding of the invention. However, it is clear that one or more embodiments can be implemented without such particular detail description. Also, for the sake of brevity, the drawings are schematic representations of well-known structures and devices.

<Method of reducing the width of the slab>
A method for reducing the width of the slab according to the embodiment of the present invention will be described with reference to the drawings. In the present embodiment, the width reduction of the slab 2 is performed using the sizing press 1 shown in FIG. The sizing press 1 has a pair of dies 3a and 3b arranged so as to face each other in the plate width direction (vertical direction in FIG. 1) of the slab 2 to be conveyed.

The pair of molds 3a and 3b have an inclined portion 31, a parallel portion 32, and an auxiliary inclined portion 33 on a contact surface (end surface facing each other) with the slab 2. The inclined portion 31, the parallel portion 32, and the auxiliary inclined portion 33 are continuously formed in order from the rear side in the transport direction 2a (direction from the left side to the right side in FIG. 1) of the slab 2. The inclined portion 31 is an end face formed by being inclined at a constant angle with respect to the conveying direction 2a so that the rear side in the conveying direction 2a is outside in the plate width direction in the plan view shown in FIG. The inclination angle θ of the inclined portion 31 with respect to the transport direction 2a and the parallel portion 32 is preferably 13 ° or more and 17 ° or less. The parallel portion 32 is an end face formed so as to extend in parallel with the transport direction 2a and the end face of the transport slab 2 on the front side of the inclined portion 31 in the transport direction 2a in the plan view shown in FIG. .. Further, the length of the parallel portion 32 parallel to the transport direction 2a is defined as L1. In the plan view shown in FIG. 1, the auxiliary inclined portion 33 is formed so as to be inclined to the front side of the parallel portion 32 in the transport direction 2a at a constant angle with respect to the transport direction 2a and to the opposite side to the inclined portion 31. It is the end face to be done. The inclination angle of the auxiliary inclined portion 33 with respect to the transport direction 2a and the parallel portion 32 is preferably 13 ° or more and 25 ° or less. The pair of molds 3a and 3b have the same shape, and have an upside-down shape in the plan view shown in FIG.

Further, the pair of molds 3a and 3b are connected to the crankshaft (not shown) through a reduction screw (not shown), and the rotation of the crankshaft causes the slabs 2 to face each other, that is, to be conveyed. It moves periodically in the plate width direction. At this time, the pair of molds 3a and 3b are configured to move in conjunction with each other in a direction in which the separation distance becomes shorter and in a direction in which the separation distance becomes longer. The amplitude, which is the amount of movement when the pair of molds 3a and 3b move periodically, depends on the amount of eccentricity of the crankshaft and is always constant. This amplitude is called the mold stroke S. The state in which the pair of molds 3a and 3b are closest to each other is referred to as the first state, and the state in which the pair of molds 3a and 3b are closest to each other is referred to as the second state. That is, the pair of molds 3a and 3b periodically move so that the positions are repeatedly changed to the first state and the second state by the rotation of the crankshaft. The operation of moving the position of the pair of molds 3a and 3b from the first state to the second state, that is, the operation of closing the pair of molds 3a and 3b is called a closing operation, and the pair of molds 3a and 3b The operation of moving the position from the second state to the first state, that is, the operation of opening the pair of molds 3a and 3b is called the opening operation.

Further, the sizing press 1 is provided with a pair of dies 3a and 3b arranged to face each other in the plate width direction of the slab 2 and pinch rolls (not shown) provided on the rear side and the front side of the pair of dies 3a and 3b. ) And. The sizing press 1 moves the pair of dies 3a and 3b in the plate width direction while intermittently transporting the slab using a pinch roll, and presses the slab 2 in the plate width direction to reduce the plate width of the slab 2. Make it smaller. The pinch roll can convey the slab 2 in the forward direction from the rear side to the front side (forward feed) and in the reverse direction which is the opposite direction of the forward direction (reverse run).

The sizing press 1 moves the pair of dies 3a and 3b in the plate width direction while intermittently transporting the slab using a pinch roll, and presses the slab 2 in the plate width direction to reduce the plate width of the slab 2. Make it smaller. The pinch roll can convey the slab 2 in the forward direction from the rear process side to the front process side (forward) and in the reverse direction opposite to the forward direction (reverse run).

Further, in the present embodiment, as a condition of width reduction, half of the width reduction amount of the slab 2 is less than the mold stroke S of the molds 3a and 3b.
The width reduction amount of the slab 2 is the amount of change in the plate width of the slab 2 due to the width reduction, and is the length obtained by subtracting _{the plate width W 1} of the slab 2 after the width reduction from _{the plate width W 0 of the slab 2 before the width reduction.} (W _0- W ₁ ). The width reduction of the slab 2 is a state in which the slab 2 is arranged in the center between the pair of molds 3a and 3b, and the pair of molds 3a and 3b are in the first state (FIG. 1). By moving from the solid line) to the second state (one-dot chain line in FIG. 1), the slab 2 is reduced in the width direction. Therefore, the width reduction amount of the slab 2 is _{determined according to the plate width W 0} before the width reduction of the slab 2, the installation positions of the pair of molds 3a and 3b, and the mold stroke S. That is, when the value of half of the width reduction amount of the slab 2 is equal to or less than the mold stroke S of the molds 3a and 3b, in the first state, as shown in FIG. 1, the pair of molds 3a and 3b are separated from each other. The distance (distance between the parallel portions 32) is larger than _{the plate width W 0 of the slab 2 before the width reduction.}

In the width reduction method of the slab 2 according to the present embodiment, the pair of molds 3a, in the first state, so that the position of the tip of the slab 2 with respect to the transport direction 2a is the position of the parallel portion 32 of the molds 3a, 3b. Transport the slab 2 between 3b.
Next, with the slab 2 stopped, the pair of molds 3a and 3b are closed to change from the first state to the second state, thereby reducing the width of the tip side of the slab 2 (downward in the width direction). (Width reduction process).

Further, the pair of molds 3a and 3b are opened to change from the second state to the first state, and the slab 2 is transported in the transport direction 2a by the transport amount D (m) (convey step). At this time, the transport amount D is a distance that satisfies the following equation (1). As described above, in the equation (1), S is the mold stroke (m), θ is the inclination angle (°) of the inclined portion 31, and L1 is the length (m) of the parallel portion 32.
S / tan θ ≦ D ≦ L1 ・ ・ ・ (1)

When the transport amount D exceeds L1, the portion that is not reduced in width to the plate width L1 is located on the front side in the transport direction 2a with respect to the parallel portion 32 in the state after the transport process. Therefore, as shown in FIG. 2, an uncompressed lower portion is generated in the slab 2 after the width reduction.
On the other hand, when the transport amount D is less than S / tan θ, the transport amount D becomes about the same as that of the conventional width reduction method, and the efficiency of width reduction cannot be improved. It becomes unsuitable. Here, in the conventional width reduction method, the transfer amount D in the transfer step is controlled to be less than S / tan θ due to the positional relationship between the pair of dies 3a and 3b and the slab 2. The reason why the transport amount D is set to less than S / tan θ will be described with reference to FIG.

In the example shown in FIG. 3, the condition of the width reduction is as shown in FIG. A state in which the transfer step shown in FIG. 3B is performed after the width reduction step shown in FIG. 3B is shown. In the case of the condition under the width reduction shown in FIG. 3, when the pair of molds 3a and 3b try to transport the slab 2 in the first state (the state of the solid line in FIG. 3B), the pair when the transport amount D is large The molds 3a and 3b of the above and the slab 2 come into contact with each other. At this time, due to the geometrical positional relationship between the pair of molds 3a and 3b and the slab 2, when the transport amount D is S / tan θ or more, the pair of molds 3a and 3b (inclined portion 31) and the slab 2 (the inclined portion of the slab 2 whose width is reduced until the plate width becomes more _{than W 1 and less than W 0) comes into contact with each other.} The S / tan θ is the inclination of the inclined portions 31 and the slab 2 of the molds 3a and 3b in the transport direction 2a when the pair of molds 3a and 3b are opened and brought into the first state after the width reduction step. The distance to the department. For this reason, in the conventional width reduction method, regardless of the width reduction conditions, in order to prevent contact between the pair of dies 3a and 3b and the slab 2 in the transfer process due to geometric restrictions due to the equipment layout, the transfer amount Width reduction has been performed under the condition that D is less than S / tan θ.

However, the present inventors have found that when the width reduction condition is that the value of half the width reduction amount of the slab 2 is less than the mold stroke S of the dies 3a and 3b, a pair of dies in the transfer step. It was found that the transport amount D can be increased because the contact between 3a and 3b and the slab 2 does not occur. In the example shown in FIG. 4, as a state of width reduction when the value of half of the width reduction amount of the slab 2 is less than the mold stroke S of the molds 3a and 3b, FIG. A state in which the transfer step shown in FIG. 4B is performed after the width reduction step shown in a) is shown. Under the condition under the width reduction shown in FIG. 4, the pair of molds 3a and 3b and the slab 2 do not come into contact with each other even when the transport amount D is as large as S / tan θ or more. That is, as in the present embodiment, in the case where the value of half of the width reduction amount of the slab 2 is less than the mold stroke S of the molds 3a and 3b, the transport amount D is set to S / tanθ. The above can be achieved, and the efficiency under width reduction can be improved.

Then, after the width reduction step, the above-mentioned transfer step and width reduction step are repeated in order to perform width reduction over the entire length of the slab 2 in the longitudinal direction, so that the plate width of the entire length in the longitudinal direction is all. The slab 2 which becomes _{W 1 is manufactured.} FIG. 5 shows a state immediately before the width reduction process is further performed after the transfer process and the width reduction process are performed a plurality of times. As shown in FIG. 5, in the present embodiment, by setting the transport amount D within the range of the equation (1), the parallel portion 32 can _{reduce the position where the plate width becomes W 0.} Width reduction can be performed over the entire length of the slab 2 in the longitudinal direction with a small number of forgings (number of presses). The slab 2 that has been subjected to width reduction is then conveyed to the next process and subjected to a process such as hot rolling to produce a steel strip.
In the present embodiment, the condition that the half value of the width reduction amount of the slab 2 is less than the mold stroke S of the molds 3a and 3b has been described, but the half value of the width reduction amount of the slab 2 is When the mold strokes S or more of the molds 3a and 3b are longer, the transport amount D is less than S / tan θ.

<Modification example>
Although the present invention has been described above with reference to specific embodiments, it is not intended to limit the invention by these descriptions. By reference to the description of the invention, one of ordinary skill in the art will appreciate the disclosed embodiments as well as other embodiments of the invention that include various modifications. Therefore, it should be understood that the embodiments of the invention described in the claims also include embodiments including these modifications described in the present specification alone or in combination.

For example, in the above embodiment, the pair of molds 3a and 3b has an inclined portion 31 and a parallel portion 32, but the present invention is not limited to such an example. For example, the pair of molds 3a and 3b may have a plurality of parallel portions. In this case, a plurality of inclined portions and parallel portions are formed in order from the rear side in the transport direction 2a on the pair of molds 3a and 3b. For example, in the molds 3a and 3b shown in FIG. 1, the inclined portion, the parallel portion, and the inclined portion may be arranged in order at the position of the inclined portion 31. Further, the inclination angle θ of the inclined portion may be different for each inclined portion. Further, when a plurality of parallel portions and inclined portions are provided, the inclined portion having the smallest inclined angle among the plurality of inclined portions is used as the inclined angle θ in the equation (1).

Further, in the above embodiment, the slab 2 is fed in the transport direction 2a in the transport step, and the slab 2 is reduced in width from the front side in the transport direction 2a, but the present invention is not limited to this example. Similar to the above embodiment, the slab 2 is reduced in width from the front side in the transport direction 2a, and then the slab 2 on the front side in the transport direction 2a of the pair of molds 3a and 3b is widened from the rear side in the transport direction 2a. It may be reduced. In this case, the slab 2 is transported in the direction opposite to the transport direction 2a in the transport step, and then the width reduction step is performed to reduce the width of the slab 2 from the rear side in the transport direction 2a. Further, in the width reduction step, the width reduction of the slab 2 is performed by the parallel portion 32 and the auxiliary inclined portion 33. Further, in the transfer step, the auxiliary inclination portion 33 is used as the inclination angle θ of the equation (1), and the transfer amount D is determined. By doing so, the width reduction of the slab 2 can be performed in two steps, so that the width reduction of the slab 2 can be performed with a larger width reduction amount. Since such width reduction reduces the efficiency of the sizing press, it is preferable to perform such width reduction when there is sufficient equipment capacity such as a small number of slabs 2 to reduce width. Further, when the slab 2 is conveyed only in the conveying direction 2a, the auxiliary inclined portion 33 may not be formed on the pair of molds 3a and 3b.

<Effect of embodiment>
The width reduction method for the slab 2 according to one aspect of the present invention is the width reduction method for the slab 2 that reduces the width of the slab 2 by intermittent forging using the pair of dies 3a and 3b. The slab 2 arranged between the slabs 2 is transported in the transport direction 2a by the transport amount D, and the pair of molds 3a and 3b are moved in the plate width direction of the slab 2. As a pair of dies 3a and 3b, a parallel portion 32 formed parallel to the end face of the slab 2 on the front side of the transport direction 2a and a transport direction rather than the parallel portion 32. The one provided on the rear side of the slab and having an inclined portion 31 inclined so that the rear side of the transport direction 2a spreads in the plate width direction is used, and half of the width reduction amount of the slab 2 by the pair of dies 3a and 3b. The value is less than the mold stroke S, which is the amount of movement of the pair of molds 3a and 3b in the plate width direction in the width reduction step, and the transport amount D satisfies the equation (1).

According to the width reduction method having the above configuration, when the slab 2 is conveyed, there is no concern about contact between the slab 2 and the pair of dies 3a and 3b, so that the transfer amount D can be set to S / tan θ or more. It is possible to improve the efficiency of the sizing press 1. Further, by setting the transport amount D to L1 or less, it is possible to prevent the occurrence of an unpressurized lower portion.

Next, the examples carried out by the present inventors will be described. In the embodiment, a slab 2 having a length of 10000 mm, a width of 1500 mm, and a thickness of 260 mm was prepared. The die stroke S of the sizing press 1 was 100 mm, the inclination angles θ of the dies 3a and 3b were 13 °, and the length L1 of the parallel portions 32 of the dies 3a and 3b was 560 mm.
Table 1 shows the conditions of the width reduction press of Examples and Comparative Examples and the investigation results after the width reduction of the slab.

In Comparative Example 1-1, the width reduction amount was 50 mm and the transport amount D was 350 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 30 times, and the time required to reduce the width of the slab 2 in the longitudinal direction was 42.0 sec.
In Example 1-1, the width reduction amount was 50 mm and the transport amount D was 450 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 23, and the time required to reduce the width of the slab 2 in the longitudinal direction was 32.2 sec.

In Example 1-2, the width reduction amount was 50 mm and the transport amount D was 550 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 19 times, and the time required to reduce the width of the slab 2 in the longitudinal direction was 26.6 sec.
In Comparative Example 1-2, the width reduction amount was 50 mm and the transport amount D was 650 mm. At this time, the number of presses required to reduce the width of the slab 2 to the total length in the longitudinal direction was 16 times, and the time required to reduce the width of the slab 22 to the total length in the longitudinal direction was 22.4 sec. Further, the amount of transport is longer than the die parallel portion length, non-pressure portion not in the plate width and W ₁ has occurred.

As can be seen by comparing Comparative Example 1-1 and Examples 1-1 and 1-2, the time required for the sizing press 1 to reduce the overall length by increasing the transport amount D is reduced, and the efficiency is reduced. It has been improved. Further, in Comparative Example 1-2, although the transfer amount D can be increased to improve the efficiency, an unpressurized lower portion is generated.
In Comparative Example 2-1 the width reduction amount was 150 mm and the transport amount D was 350 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 32, and the time required to reduce the width of the slab 2 in the longitudinal direction was 44.8 sec.

In Example 2-1 the width reduction amount was 150 mm and the transport amount D was 450 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 24, and the time required to reduce the width of the slab 2 in the longitudinal direction was 33.6 sec.
In Example 2-2, the width reduction amount was 150 mm and the transport amount was 550 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 20 times, and the time required to reduce the width of the slab 2 in the longitudinal direction was 28.0 sec.

In Comparative Example 2-2, the width reduction amount was 150 mm and the transport amount was 650 mm. At this time, the number of presses required to reduce the width of the slab 2 in the longitudinal direction was 17 times, and the time required to reduce the width of the slab 2 in the longitudinal direction was 23.8 sec. Further, the conveyed amount D was longer than the length L1 of the parallel portion 32, and an uncompressed lower portion was generated.
As can be seen by comparing Comparative Example 2-1 and Examples 2-1 and 2-2, the time required for the sizing press 1 to reduce the overall length by increasing the transport amount D is reduced, and the efficiency is improved. It has been improved. Further, in Comparative Example 2-2, although the transfer amount D can be increased to improve the efficiency, an unpressurized lower portion is generated.
According to the above invention, it was confirmed that the efficiency of the sizing press 1 can be improved.

1 Sizing press 2 Slab 2a Transport direction 3a, 3b Mold 31 Inclined part 32 Parallel part 33 Auxiliary inclined part

Claims (1)

In the slab width reduction method in which the slab is width-reduced by intermittent forging using a pair of dies.
A transport process in which the slabs arranged between the pair of molds are transported in the transport direction by a transport amount D, and a transport step.
A width reduction step of reducing the width of the conveyed slab by moving the pair of dies in the plate width direction of the slab.
With
As the pair of molds, a parallel portion formed in parallel with the end face of the slab on the front side in the transport direction and a rear side in the transport direction from the parallel portion are provided, and the rear side in the transport direction is the said. Use one that has an inclined portion that is inclined so as to spread in the plate width direction.
Half of the width reduction amount of the slab by the pair of dies is less than the mold stroke which is the movement amount of the pair of dies in the plate width direction in the width reduction step.
The transport amount D satisfies the following formula (1) and is 450 mm or more and 550 mm or less.
A method for reducing the width of a slab, wherein the amount of width reduction is 50 mm or more and 150 mm or less.
S / tan θ ≦ D ≦ L1 ・ ・ ・ (1)
S: Mold stroke (m)
θ: Inclination angle (°) of the inclined part
L1: Length of parallel part (m)

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