JPH04172105A - Method for rolling vary thin hot strip - Google Patents

Abstract

PURPOSE:To replace the off-gage part of a special material with a different material and to improve the yield of the special material by welding the different material to the front and rear ends of a slab of special material and enabling rolling into a very thin strip with a steckel mill. CONSTITUTION:The different material 21 is welded to the front and rear ends of the slab 20 of special material and this slab 22 is rolled by reversing rolling that the rear end of a strip 14 passes through a rolling mill 9 with the steckel mill 5 before the strip 14 is made into a prescribed thickness. Then, when the thickness of strip 14 is smaller than the prescribed thickness, it is rolled into the prescribed thickness of product by reversing rolling without pulling out the rear end of the strip 14 from a surface coiler on the uncoiling side while coiling the strip 14 with the furnace coiler.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method of hot rolling ultra-thin strip using a Steckel mill to hot-roll a special material from a slab to ultra-thin strip.

[Conventional technology]

Traditionally, special materials were rolled into slabs of special dimensions using a blooming mill from four ingots, as the required quantity was small, and a tandem hot strip mill equipment was used to roll the special materials into slabs of special dimensions.
It is rolled into a coil of about ta.

The required thickness of the product is even thinner, so re-rolling is necessary, but special materials are mainly materials that are difficult to process, or in order to ensure material properties, many require re-rolling at high temperatures. . For this reason, In1. pubIiction
As described in Nambet Wo, Publication No. 89/11348, a product having a predetermined thickness was obtained by heating the coil again or rolling the strip while heating it before rolling.

In addition, there is a Stetskel mill facility as described in JP-A No. 59-101205, which manufactures special materials on a relatively small scale. Generally speaking, the limit is 1.6m+a to 2 days due to the workability of threading the sheets, winding them around a coiler mandrel, etc.

Although it is not a hot rolling technology for special material slabs, it is described in Japanese Patent Application Laid-Open No. 1-11310 as a technology for joining dissimilar materials to product rolled materials.
There is Publication No. 1, in which a thin plate of a dummy coil is bonded to the final hot-rolled thin plate material in order to facilitate sheet threading and improve product yield when the cold rolling mill restarts operation.

[Problem to be solved by the invention]

As mentioned above, in hot rolling technology that rolls special materials from slabs to ultra-thin strips, when tandem hot strip mill equipment is used, re-rolling with a special mill is necessary to obtain the final product with the required thickness. It is necessary to do so, and the equipment for that purpose is necessary.

Additionally, it is generally difficult to hot-roll ultra-thin strips using Steckel mill equipment.

JP-A-1-113101 does not provide a hot rolling technique for rolling special materials from slabs to ultra-thin strips.

The first object of the present invention is to provide a hot rolling method for ultra-thin strips that enables hot rolling from slabs to ultra-thin strips in a Steckel mill, and that enables high-yield rolling of special materials during the rolling. It is.

A second object of the present invention is to provide a method of hot rolling an ultra-thin strip in which the off-gauge portions at the leading and trailing ends of the strip do not affect the next process when the strip is rolled to an ultra-thin strip using a Steckel mill.

[Means to solve the problem]

The first purpose is to improve the front and rear ends of special material slabs in a hot ultra-thin strip rolling method in which special material is hot-rolled from slabs to ultra-thin strips using a Stutskel mill with furnace coilers placed before and after the rolling mill. Dissimilar metals are welded to the slab, and before the strip reaches a predetermined thickness, the slab is rolled by reversing rolling in which the rear end of the strip passes through the rolling mill, and when the strip reaches a predetermined thickness or less, This is achieved by rolling the strip to a predetermined product thickness by reversing rolling while winding the strip in a furnace coiler and without removing the rear end of the strip from the unwinding furnace coiler.

The second object is to arrange the shear on the exit side of the Steckel mill in the rolling method, and after rolling the slab to a predetermined product thickness, cut the front and rear ends of the strip with the shear to remove at least a part of the foreign material. This is achieved by winding a strip made mainly of special material onto a product take-up reel.

Preferably, in the above rolling method, a heating device is disposed upstream of the Steckel mill, and the slab is heated by the heating device and then rolled in the Steckel mill.

[Effect]

In the rolling process using a Steckel mill, as mentioned above, the product thickness is generally limited to about 1.6 mm to 2 fins. To make the strip thinner than this, there is a method of reversing rolling with the leading and trailing ends of the strip left on the mandrel of the furnace coiler after securing the rolling temperature. It is possible to roll up to However, in this case, since the strip is rolled with several turns remaining on the mandrel, an off-gauge portion occurs at the front and rear ends of the strip, and this portion does not become a product and reduces the yield. Additionally, when transitioning from rolling in sheet form to winding rolling, the leading and trailing ends of the strip are crop-cut before being wound into the furnace coiler, but if these crop cuts are included, the yield will further decrease. do. Many of these types of special materials are very expensive, resulting in a low yield and a large economic loss.

In the present invention, a different material, such as common steel, is welded to the front and rear ends of a special material slab, and this slab is rolled in a Steckel mill. When transitioning from sheet rolling to winding rolling, a crop cut is made at the leading and trailing ends of the strip, and by cutting a part of the dissimilar material, all of the special material is secured.

Next, the special material and the welded dissimilar materials are rolled to the same thickness by using a furnace coiler to take up and roll the strip to a predetermined thickness by reversing rolling in which the rear end of the strip passes through the rolling mill. When the strip has a predetermined thickness or less, it is rolled to a predetermined product thickness by reversing rolling using a furnace coiler with several turns left at the front and rear ends of the strip on the mandrel. At this time, the several turns wound around the mandrel and the distance from the mandrel to the rolling mill roll become the unrolled part, that is, the above-mentioned off-gauge part, but in the present invention, this part corresponds to the dissimilar material part, and the special material Since no off-gauge parts are formed in this method, the rolling yield of special materials is dramatically improved.

In addition, after the slab is rolled to a predetermined product thickness as described above, at least a portion of the dissimilar material portion at the front and rear ends of the strip is cut off and wound onto a reel, so that the dissimilar material portion (off-gauge portion) can be transferred to the next process. influence is removed.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 3.

FIG. 1 shows the entire equipment for carrying out the rolling method of this embodiment, which includes a welding point 1, a heating furnace 2, a descaler 3, a crop shear 4, a Stetskell mill 5, a crop shear 6, a product take-up reel 7, and a carry-out table 8. They are arranged in this order. The Steckel mill 5 has a rolling mill 9 and a furnace coiler 10.11 located before and after the mill 9.

At welding point 1, as shown in Fig. 2, special material slab 2
A dissimilar material 21 is welded to the front and rear ends of 0 in the rolling direction to form a slab 22 of dissimilar material. As the foreign material 21, for example, inexpensive common steel is used. The slab 22 is sent to the heating furnace 2 and heated to a predetermined temperature. The heated slab 22 is removed by a descaler 3 to remove primary scale generated during heating, and then sent to a Steckel mill 5 and rolled by a mill 9 to a predetermined product thickness. The details are as follows.

First, in the mill 9, the sheet is lever-rolled to a predetermined thickness without being wound up on the furnace coiler 10 or 11. This reversing rolling is generally performed to a thickness of about 20 to 25 days. Next, the rolled material having a predetermined thickness is crop-cut at the front and rear ends by a crop shear 4 on the input side of the mill, and while being rolled in a mill 9, it is passed through a furnace coiler 11 on the rear side.
When the rear end of the strip passes through the mill 9, the rear end of the rolled material is rolled up by the mandrel 12 (see Figure 3) of the front furnace coiler 10 in reverse pass rolling. is rolled until it passes through mill 9.

This rolling is repeated until the thickness of the rolled material is usually 1.5~2I.
When the strip 14 has reached a certain level, as shown in FIG. Rolling is performed while winding with a mandrel 13. Front side furnace coiler 10
When the strip on the mandrel 12 becomes several turns, the pass direction is reversed while leaving it as it is. Such passes are repeated to roll the strip to a predetermined thickness of approximately 0.3 mm. One pass before the final pass, the front furnace coiler 1 rolls until the rear end of the strip 14 comes off the mandrel 13 of the rear furnace coiler 11.
Rolling is performed while winding with a mandrel 12 of 0.0 mm.

Thereafter, the strip 14 is conveyed toward the reel 7 in the final pass.

The unrolled part at the tip of the strip 14 conveyed from the Steckel mill 5, that is, the off-gauge part, is cut by the shear 6, the cut off-gauge part is carried out of the line by the table 8, and the remaining product strip 14 is It is wound on reel 7. The off-gauge portion at the rear end of the strip is also cut by the shear 6 and carried out by the table 8. In this way, an ultra-thin product made of special material that has been rolled to a predetermined thickness is wound onto the reel 7.

In the above embodiment, the shafts 4 and 6 were provided on both sides of the Stetskell mill 5, but only the shaft 6 on the outlet side was provided.
This may also be used as the entrance side shaft 4.

Furthermore, when cutting the front and rear ends of the strip 14 with the shear 6, it is also possible to leave a part of the dissimilar material part without cutting it entirely, or to use it as a leader strip in the next process without cutting the off-gauge part at all. .

As described above, according to this embodiment, it is possible to roll a slab to an ultra-thin strip using the Stetskell mill 5, and the dissimilar material 21 is welded to the front and rear ends of the slab 22, and that part becomes an off-gauge part and can be cut. This dramatically improves the rolling yield of special materials. A concrete example of this is as follows.

For example, the thickness of the slab of special material 20 is 120th, and the slab length is 5000111+=! : When rolling this as it is, the distance between mill 9 and furnace 34919.11 is 1.
If the mandrel diameter is φ800mm, the unpressurized extension will be about 28000+nm at both ends, and if the crop loss is added to this, the total loss will be about 700mm in terms of slab length, and the total slab length will be 5000+nm.
This corresponds to about 15% of nm. In this embodiment, this amount is applied by welding different materials, so the yield of special materials is improved by about 15%.

Furthermore, according to this embodiment, at least a portion of the dissimilar material portions at the front and rear ends of the rolled strip are cut and wound onto the reel 7, so that the influence of the dissimilar material portions on the next process is eliminated.

In addition, in Stetskell mill rolling, a temperature drop at the leading and trailing ends of the strip often occurs, and in the case of special materials, this temperature drop may make it impossible to roll the strip. Since the parts are welded, even if the temperature drops in that part, there is no risk of the rolling becoming impossible, and stable operation can be achieved.

〔Effect of the invention〕

According to the present invention, special materials can be rolled into ultra-thin strips using a Stetskell mill, and the off-gauge portion of expensive special materials can be replaced with inexpensive different materials, so the rolling yield of special materials can be dramatically improved. This has a high economical effect, and furthermore, since the unrolled parts at the front and rear ends are removed, a product can be obtained that does not affect the next process.

Furthermore, even if the temperature at the leading and trailing ends of the strip drops during rolling in the Stetskell mill, since the dissimilar material is welded to that part, the risk of the rolling becoming impossible is avoided, and stable operation is possible.

[Brief explanation of drawings]

FIG. 1 is a schematic diagram showing the entire equipment for carrying out the rolling method according to an embodiment of the present invention, FIG. 2 is a perspective view of a slab made by welding a different material to a special material, and FIG. 3 is an operation of a Stetskell mill. It is a figure showing a state. ■...Welding location 2...Heating furnace 5...Stetskell mill 6...Shell 7...Product take-up reel 9...Rolling mill 10.11...Furnace coiler 12.13...・Mandrel Applicant: Hitachi, Ltd. Nippon Kokan Co., Ltd. Agent: Patent Attorney Haruhi Yuki 1...Welding location 2...Heating furnace 5...Stetskel mill 6...Shell 7...Product take-up reel 9...Rolling mill 10.11...Furnace coiler 1213...Mandrel

Claims (3)

[Claims] (1) In the hot ultra-thin strip rolling method in which special material is hot-rolled from a slab to an ultra-thin strip using a Steckel mill with furnace coilers placed before and after the rolling mill, dissimilar materials are welded to the front and rear ends of the special material slab. The slab is rolled in the Steckel mill by reversing rolling in which the rear end of the strip passes through the rolling mill before the strip reaches a predetermined thickness, and when the strip reaches a predetermined thickness or less, the slab is rolled. A rolling method comprising rolling the strip to a predetermined product thickness by reversing rolling while winding the strip in the furnace coiler and without removing the rear end of the strip from the furnace coiler on the unwinding side. (2) In the method for hot rolling ultra-thin strip according to claim 1, a shear is disposed on the exit side of the Steckel mill, and after rolling the slab to a predetermined product thickness, the front and rear ends of the strip are cut by the shear. A rolling method characterized in that at least a part of the foreign material is cut off using a rolling process, and only a strip mainly made of the special material is wound onto a product take-up reel. (3) The hot ultra-thin strip rolling method according to claim 1, wherein a heating device is disposed upstream of the Steckel mill, and the slab is heated by the heating device and then rolled by the Steckel mill. rolling method.