JP6857312B2 - Manufacturing method of slab rolls and steel pieces - Google Patents

Description

The present invention relates to a slab roll for a reversible rolling mill that rolls an ingot or a slab into a steel piece having a predetermined cross section, and a method for manufacturing the steel piece.

The lump roll used in the conventional reversible rolling mill has, for example, a pair of lump rolls having a plurality of calibers having different shapes, as shown in FIG. The caliber has a square, octagonal, or round shape. In the block rolling using this block roll, the steel ingot or slab is first rolled into a square cross section with a square intermediate caliber. Next, this square cross section is rolled into a cross section having an octagon shape or the like. Finally, it is common to finish the steel piece with a circular cross section with a round type molded caliber.

In a slab roll having a plurality of calibers for rolling a steel ingot or a slab and sequentially rolling it into a steel piece having a circular cross section, the octagon having a shape close to the final shape among the plurality of calibers. The shape of the mold or round mold caliber wears and deteriorates due to rolling. This occurs because the forming caliber in the post-rolling stage has a longer total rolling length than the intermediate caliber in the pre-rolling stage. Then, the molded caliber whose shape has deteriorated needs to be turned to maintain a normal shape on a regular basis to obtain the squareness and roundness of the final shape.

On the other hand, Patent Document 1 proposes that the life of the molded caliber in the post-rolling stage can be brought closer to the life of the intermediate caliber in the pre-rolling stage. This is to increase the number of intermediate calibers in order to match the wear amount of the molded caliber used in the post-rolling stage of the slab roll with the wear amount of the intermediate caliber used in the pre-rolling stage as much as possible. As a result, the period until the lump roll is re-turned is lengthened, and the lump roll having an extended roll life can be obtained, which is excellent.

Japanese Unexamined Patent Publication No. 2008-149338

In the lump roll disclosed in Patent Document 1 described above, the total rolling length of each caliber is taken into consideration, and the number of calibers is arranged so that the total rolling length is as uniform as possible. It is advantageous in that the amount of wear can be made uniform and the turning time of the roll can be extended.
However, according to the study of the present inventor, the ingot roll used in the reversible rolling mill becomes a ingot roll when rolled with the cross-sectional shape of a steel ingot or slab or the above-mentioned forming caliber such as an octagon type or a round type. It was confirmed that there was a problem of receiving a large thrust force. This problem of thrust force greatly affects the shape accuracy such as twist, squareness and roundness of the steel piece to be obtained, and causes a decrease in yield and efficiency in the subsequent cutting process of the steel piece. Become.

An object of the present invention is to solve the problem of thrust force generated in a slab roll in a slab for obtaining a steel slab from a steel ingot or a slab, and to obtain a steel slab having excellent shape accuracy. Is to provide a manufacturing method of.

The present inventor has investigated the problem of thrust force generated in a lump roll in lump rolling using a pair of lump rolls for a reversible rolling mill, and a step in which the lump rolls are engaged with each other in the roll axial direction. We have found that the shape accuracy of the obtained steel piece can be greatly improved by adopting the attached portion, and have reached the present invention.

That is, the present invention includes a stepped portion in which the pair of lump rolls for a reversible rolling mill having an intermediate caliber and a forming caliber for rolling into a steel piece having a predetermined cross section are engaged with each other. It is a lump roll to roll.
It is preferable that the stepped portions are arranged at two or more locations in the roll axis direction.
It is more preferable that the stepped portions are arranged on both sides of the molded caliber in the roll axis direction.
The molded caliber is suitable for a round type.

Further, the present invention includes a stepped portion in which a pair of lump rolls for a reversible rolling mill provided with an intermediate caliber and a forming caliber can mesh with each other, and the stepped portion meshes when rolling with the intermediate caliber. It is a method of manufacturing a steel piece in which the stepped portion meshes when rolling with the formed caliber without being in a state.

According to the present invention, the problem of thrust force generated in a slab roll in slab rolling can be dramatically improved, which is a useful technique for manufacturing, for example, a steel piece having a circular cross section, that is, a round billet.

FIG. 5 is a cross-sectional configuration diagram showing an example of a lump roll of the present invention. The schematic diagram which shows the outline of the cross section of the steel piece obtained by using the slab roll of this invention. The schematic diagram which shows the outline of the cross section of the steel piece obtained by using the slab roll of the conventional example. FIG. 6 is a schematic cross-sectional view showing an example of a conventional lump roll.

As described above, an important feature of the present invention is the adoption of a stepped portion in which the lump rolls are opposed to each other and mesh with the pair of lump rolls for a reversible rolling mill.
FIG. 1 shows an example of a schematic cross-sectional view of the lump roll of the present invention. In FIG. 1, the axisymmetric portion of the pair of upper and lower symmetry rolls is omitted. The slabbing roll 1 of the present invention is composed of a pair of rolls and can be used in a reversible rolling mill. This can contribute to space saving as compared with a rolling mill in which a rolling stand is arranged in tandem. The ingot roll of the present invention includes an intermediate caliber for rolling a steel ingot or a slab into an intermediate steel piece, and a molded caliber for rolling into a steel piece having a predetermined cross-sectional shape.

In the state shown in FIG. 1 [A], the ingot roll 1 of the present invention is rolled into an intermediate steel piece by passing a steel ingot or a slab through an intermediate caliber such as a square type or an octagon type (not shown) and rolling it. be able to. Then, as shown in FIG. 1 [B], for example, this intermediate steel piece is finally formed into a steel piece having a circular cross section with a round type forming caliber 2.
The lump roll 1 of the present invention includes a stepped portion 3 in which the lump rolls face each other and mesh with each other in the roll axis direction. This is because, as shown in FIG. 1 [B], when the forming caliber 2 of the lump roll rolls into a steel piece having a predetermined cross section, the stepped portions engage the pair of upper and lower lump rolls. .. The stepped portion 3 provided in the lump roll 1 of the present invention has a height at which it does not mesh when rolled with an intermediate caliber other than the molded caliber 2.

By adopting this stepped portion, the lump roll of the present invention can reduce the influence of the thrust force generated on the lump roll during rolling with a forming caliber for obtaining a steel piece having a predetermined cross section. As a result, the shape of the formed caliber can be maintained with high accuracy and rolled, the stabilization of the shape of the obtained steel piece can be promoted, and the decrease in yield can be suppressed in the subsequent cutting process of the steel piece.

As shown in FIG. 1, the stepped portion 3 of the lump roll 1 of the present invention forms, for example, a protrusion (convex) portion on the upper roll 1a and faces the convex portion of the upper roll 1a on the lower roll 1b. A groove (concave) is formed at the position so that it meshes. In short, the stepped portion 3 serves as a so-called inlay.
By arranging the stepped portion at one position in the axial direction of the lump roll, it is possible to reduce the influence of the thrust force generated on the lump roll during rolling with the forming caliber. In the present invention, it is preferable to arrange the stepped portions at two or more places. As a result, the thrust force is significantly reduced, the error between the vertical diameter and the horizontal diameter can be minimized, and rolling can be performed while maintaining the shape of the formed caliber with higher accuracy.

Further, it is more preferable that the stepped portions are arranged on both sides of the molded caliber in the axial direction of the lump roll. As a result, the influence of thrust force can be minimized, the shape holding force of the molded caliber is strengthened, and digging, misalignment, twisting, etc. are suppressed, and a steel piece with high shape accuracy can be obtained. Possible rolling is possible.

In FIG. 1, the molded caliber provided in the lump roll of the present invention is a round caliber in order to obtain a steel piece having a circular cross section. This can also be a square or box caliber to obtain a piece of steel with a square cross section.

Here, a round billet was obtained by rolling into a steel piece having a cross-sectional shape of 160 mm using the slab roll 1 of the present invention shown in FIG. 1 with a reversible rolling mill. When rolling using the round type molded caliber 2, the stepped portions 3 were engaged with each other so that the lump rolls faced each other for rolling.
Then, the shape of the cross section of the obtained steel piece was measured, and the contour was modeled. The result is shown in FIG. The steel piece rolled using the lump roll of the present invention had a shape along the reference line of FIG. When the diameter of the steel piece is measured on the entire circumference of a circular cross section, the difference between the maximum diameter and the minimum diameter is 1 mm or less, there is no twist, and the roundness is sufficient as a round billet. The effectiveness was confirmed.

Further, in a reversible rolling mill, a round billet was obtained by rolling into a steel piece having a cross-sectional shape of 160 mm using a lump roll shown in FIG. 4 which does not have the stepped portion according to the present invention. ..
Then, the shape of the cross section of the obtained steel piece was measured, and the contour was modeled. The result is shown in FIG. The steel pieces rolled using the lump roll not provided with the stepped portion according to the present invention were not twisted but had discrepancies. When the diameter of the steel piece was measured on the entire circumference of the circular cross section, the difference between the maximum diameter and the minimum diameter exceeded 10 mm, and it was confirmed that the steel piece had an unsuitable roundness as a round billet.

1. 1. Block roll 1a. Upper roll 1b. Lower roll 2. Molded caliber 3. Stepped part

Claims (5)

In a pair of ingot rolls for a reversible rolling mill having an intermediate caliber and a forming caliber for rolling into a steel piece having a predetermined cross section in the roll axis direction, the pair of ingot rolls are provided with a stepped portion in which they are opposed to each other and mesh with each other. In the stepped portion, one roll is formed with a protrusion, and the other roll is formed with a groove in which the protrusion is engaged at a position facing the protrusion of the one roll. The protrusion has a height that does not mesh with the groove when the ingot or slab is passed through the intermediate caliber and rolled into the intermediate steel piece, and the intermediate steel piece is passed through the formed caliber. slabbing roll, characterized by chromatic said groove meshing with height when rolling steel pieces of a predetermined cross section in wood. The lump roll according to claim 1, wherein the stepped portions are arranged at two or more locations in the roll axis direction. The lump roll according to claim 1 or 2, wherein the stepped portions are arranged on both sides of the molded caliber in the roll axial direction. The lump roll according to any one of claims 1 to 3, wherein the molded caliber is of a round shape. A pair of reversible rolling mill slab rolls having an intermediate caliber and a forming caliber in the roll axis direction are provided with a stepped portion capable of engaging with each other, and the stepped portion has a protrusion formed on one of the rolls. The other roll is formed with a groove in which the protrusion is engaged at a position facing the protrusion of the one roll, and a steel ingot or a slab is passed through the intermediate caliber and rolled to be intermediate. When rolling into a steel piece, the stepped portion is not in a meshed state, and when the intermediate steel piece is passed through the formed caliber and rolled into a steel piece having a predetermined cross section, the stepped portion is engaged. A characteristic method for manufacturing steel pieces.

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