JPH07108338A - Metal mold for edging press device - Google Patents

Abstract

PURPOSE:To prevent the generation of the crack in the metal bold under edging of a hot slab. CONSTITUTION:The press metal mold having inclined parts 4 expanded and inclined to the slab advance side and flat parts 3 facing both transverse directions of the hot slab extracted from a heating furnace is set in its width in correspondence to the slab edging draft while the slab is made to travel continuously or intermittently and thereafter, the slab is edged by attaching and detaching the metal mold to and from the slab, by which the metal mold 2 for the edging press device for the hot slab is obtd. The end surfaces of the parallel parts 3 and inclined parts 4 of the metal mold 2 are provided with recesses 5 and the boundary parts of the parallel parts 3 and the inclined parts 4 are formed to smooth curved shapes. As a result, the generation of the crack of the metal mold is prevented and the life thereof is greatly prolonged.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a die for a width reduction press apparatus for performing width reduction of a hot slab extracted from a heating furnace in a hot rolling line.

[0002]

2. Description of the Related Art Hot rolled products are produced by heating a slab in a heating furnace and hot rolling with a rough rolling machine or a finish rolling machine to obtain a thickness of 1.0 to
It is manufactured by making a 25.4 mm strip, winding it on a coil, cooling it, and then treating it in various conditioning lines.
The slab width in the hot rolling is determined according to the coil width. The relationship between the slab width and the coil width is generally associated with the edger ability and the width accuracy. In terms of process operation, it is desirable to integrate slab sizes, and in particular because of the need to integrate continuous casting lots, the width reduction capacity of the edger tends to be increased.

The edger of the slab is classified into a width rolling method using a vertical rolling roll and a sizing press method in which a width reduction is performed by a width reduction press. In the sizing press, a pair of dies having a parallel portion and an inclined portion that is expanded and inclined toward the slab entry side are arranged opposite to each other on the crankshaft driven by a hydraulic cylinder attached to a fixed portion or a motor, and between the dies. The slab is passed through continuously or intermittently, and the dies are moved toward and away from each other without restraining the upper and lower sides of the slab to perform width reduction to a predetermined width. These sizing presses are slightly inferior in rolling ability compared to width rolling with vertical rolling rolls, but on the other hand, the fish tail at the front and rear ends of the rolled material generated after hot rolling can be made small, and the yield is good, and the dogbone The feature is that the cross-sectional shape of is less likely to be concentrated in the vicinity of the edge portion, and good flatness of the rolled material is easily obtained.

As a die for performing the width reduction of the slab by the sizing press, an integral die using heat resistant steel such as tool steel is used. The mold under the width reduction of the hot slab is repeatedly heated and cooled, and due to the thermal stress generated thereby, a crack 22 due to thermal strain is generated on the surface of the mold 21 as shown in FIG. For this reason, the life of the mold of the width reduction press is controlled by the time until cracks due to thermal strain occur and the rate of progress of the cracks.

As a measure for extending the life of the mold of the above-mentioned width reduction press, a conventional method is to prepare a plurality of pairs of the same mold for each step and use them alternately (Japanese Patent Laid-Open No. 55-55-55).
No. 86637), a mold in which a plurality of ceramic tiles are provided at intervals on the surface in the vicinity of the boundary between the parallel part of the mold and the inclined part on the entrance side (JP-A-63-252633). A mold with a slit formed on the surface near the boundary between the parallel portion and the inclined portion on the entrance side (Japanese Patent Laid-Open No. 63-25263).
No. 4) has been proposed.

[0006]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention
Although the method disclosed in Japanese Patent No. 637 can extend the life of the mold, heat generated between the mold surface part where heating and cooling are repeated and the mold back surface part kept at a substantially constant temperature. Since generation of stress itself cannot be prevented, if a mold is used for a long time, cracks will eventually occur on the mold surface. Further, the mold disclosed in JP-A-63-252633 is
It is inevitable that the ceramic tile itself will crack due to the impact of rolling down, and that the ceramic tile will come off due to the breakage of the joints that adhere to it. Not in. Furthermore, the mold disclosed in Japanese Patent Laid-Open No. 63-252634 has a new problem that cracks occur due to the lack of slit intersection points.

An object of the present invention is to prevent cracks from being generated in a mold under the width reduction of a hot slab without increasing the size of the apparatus and to reduce the rate of propagation of the generated cracks, thereby significantly extending the life. The object of the present invention is to provide a die for a width reduction press device that can perform such a reduction.

[0008]

Means for Solving the Problems As a result of various tests and researches to achieve the above object, the inventors of the present invention formed a recess on the end surface of the inclined portion and the parallel portion of the die to form a die. The thermal strain caused by the thermal expansion and contraction of the surface is absorbed by the opening and closing of the dents, the thermal stress near the mold surface is relaxed and the cracks can be prevented from occurring, and the rate of propagation of the generated cracks inside the mold is reduced. It was confirmed that this is possible, and that the generation of cracks due to rolling impact at the boundary can be significantly mitigated by making the boundary between the parallel portion and the inclined portion into a smooth curved shape, and arrived at the present invention.

That is, according to the present invention, while the hot slab extracted from the heating furnace is continuously or intermittently fed, the hot slab is parallel to the slab entrance side provided on both sides in the width direction of the slab. After setting the width of the press die having a portion in accordance with the slab width reduction amount, the width of the hot slab is reduced to a predetermined width by approaching and separating the width of the slab. A die for a width reduction press device, characterized in that a recess is provided in the end surface of each of the inclined portion and the inclined portion, and a boundary portion between the parallel portion and the inclined portion is formed into a smooth curved shape.

[0010]

In the die of the width reduction pressing apparatus of the present invention, since the end surface of the inclined portion and the parallel portion of the die are provided with the dents, the thermal distortion caused by the thermal expansion and the thermal contraction of the die surface is dented. It is absorbed by opening and closing, the thermal stress in the vicinity of the mold surface is relieved, cracks can be prevented from occurring, and the rate of propagation of the generated cracks into the mold can be reduced. In addition, since the boundary between the parallel portion and the inclined portion is formed into a smooth curved line, the generation of cracks due to the rolling impact at the boundary can be significantly mitigated, and the life of the mold can be significantly extended.

Although it is desirable that the bottom surface of the recess provided on the end surface of the inclined portion and the parallel portion of the mold have a rounded shape, substantially the same effect can be obtained even if it is V-shaped or concave. Further, it is also an effective means to prevent the occurrence of slab flaws due to the transfer of the dents by removing the end of the slab contact portion as the dents provided on the end face surface in the thickness direction of the mold.

[0012]

【Example】

Embodiment 1 Hereinafter, details of the present invention will be described with reference to FIGS. 1 to 3 showing an embodiment. FIG. 1 is a perspective view showing a situation of a width reduction press, FIG. 2 is a perspective view of a mold of a width reduction press device of the present invention, and FIG. 3 is a perspective view of a mold for explaining slab flaw generation prevention. 1 and 2, 1 is a slab, 2
Is a mold made of a heat-resistant material such as cast steel or tool steel, 3 is a mold 2
Parallel part 4 parallel to the slab 1, 4 is an inclined part provided on the slab 1 entry side of the mold 2, and 5 is a direction perpendicular to the end boundary line on the end faces of the parallel part 3 and the inclined part 4 of the mold 2. The recesses provided at predetermined intervals are configured to absorb the thermal strain generated by the thermal expansion and contraction of the surface of the mold 2 by opening and closing the recess 5. Further, at the end portions of the parallel portion 3 and the inclined portion 4 of the die 2, a smooth curved shape is formed on the end surface which is in contact with the slab 1 to prevent chipping due to a rolling impact at the boundary portion of the die 2. To do. Furthermore, as shown in FIG.
The recess 5 provided in the thickness direction of the mold 2 is configured to avoid the end portion of the contact portion 6 with the slab 1 and prevent the slab from being scratched by transferring the recess 5.

By virtue of the above-mentioned structure, the die 2 is pressed under the width reduction of the slab 1 by the width reduction press device.
The thermal strain caused by the thermal expansion and contraction of the surface is absorbed by the opening and closing of the recesses 5 provided on the end faces of the parallel portion 3 and the inclined portion 4 of the mold 2 at a predetermined interval in the direction perpendicular to the end boundary line, The thermal stress in the vicinity of the surface of the mold 2 can be relaxed to prevent the occurrence of cracks, and the rate of propagation of the generated cracks into the mold 2 can be reduced. Further, by forming a smooth curved shape at the boundary portion of the parallel portion 3 and the inclined portion 4 of the mold 2 that contacts the slab 1, it is possible to prevent chipping of the boundary portion of the mold 2 due to a rolling impact. The life of the mold 2 can be greatly extended.

Example 2 A slab having a thickness of 212 mm and a width of 1300 mm was prepared with a total length of 14
50 mm in diameter on the end surface of the parallel part and the inclined part of the mold of 00 mm, thickness 500 mm, parallel part length 500 mm
m, dents having a depth of 10 mm are provided at intervals of 100 mm, and the inclined part entry side radius is 12 mm, the boundary radius between the inclined part and the parallel part is 80 mm, the parallel part rear end radius is 20 mm.
Using a pair of molds, the width reduction amount is 300 mm, and when the mold wears a predetermined amount, it is ground and reused repeatedly, and the slab processing tonnage per time and total use The number of days was measured. The result is shown as A in FIG. For comparison, the total length is 1400 mm and the thickness is 5
A conventional mold with a length of 00 mm and a parallel portion length of 500 mm was used, and after width reduction under the same conditions, the mold was repeatedly ground and reused when it was worn by a specified amount, and the number of tons processed per time was increased. And the total number of days used was measured. The result is shown as B in FIG.

As shown in FIG. 4, in the case of width reduction A using the mold of the present invention, the slab processing tonnage of about 11 is performed once.
0000 tons, the replacement cycle is 20 days / once, whereas in the case of B, which has been width-reduced using a conventional mold, the slab processing tonnage of about 53000 tons / time, the replacement cycle is 10 days / once. It had a life of about twice as long.

[0016]

As described above, the mold of the present invention is
The thermal expansion and thermal contraction of the mold surface that occurs during the width reduction of the hot slab is absorbed by opening and closing the dents, and the thermal stress near the mold surface can be relaxed to prevent the occurrence of cracks. It is possible to reduce the growth rate of cracks inside the mold, prevent chipping of the boundary portion of the mold due to rolling impact, and significantly extend the life of the mold.

[Brief description of drawings]

FIG. 1 is a perspective view showing a situation of a width reduction press.

FIG. 2 is a perspective view of a mold of the width reduction pressing device of the present invention.

FIG. 3 is a perspective view of a mold for explaining the prevention of slab flaw generation.

FIG. 4 is a diagram illustrating the T of the mold of the present invention and the conventional mold in Example 2.
It is a graph which shows the relationship between the total number of days of use and the slab processing tonnage per time.

5A and 5B are explanatory views of the crack generation of the mold of the width reduction pressing device, FIG. 5A is an overall perspective view of the mold, and FIG. 5B is an enlarged view of the crack generation portion at the position A in FIG. 5A. Is.

[Explanation of symbols]

 1 Slab 2, 21 Mold 3 Parallel part 4 Inclined part 5 Recess 6 Contact part 22 Crack

Claims (1)

[Claims] 1. A hot slab extracted from a heating furnace is continuously or intermittently run, and a sloped portion parallel to a slab entrance side provided parallel to both sides of the slab width direction and a parallel portion are provided. The press die having, after the width is set corresponding to the slab width reduction amount, in the die of the width reduction press device of the hot slab to perform the width reduction to a predetermined width by approaching and separating,
A die for a width reduction press, characterized in that a recess is provided on the end surface of the parallel portion and the inclined portion of the die, and the boundary between the parallel portion and the inclined portion is formed into a smooth curved line.