JPS5820681B2 - Hot endless continuous rolling method for steel strip - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for obtaining a copper strip by hot rolling, in which the copper strip is rolled continuously without breaks in the finish rolling stage.

In this invention, endless continuous rolling refers to two
This refers to continuous finish rolling without any cuts.

Most mass-produced metal products are made into products through ingot formation, hot processing (rolling), and cold processing (rolling).

Compared to cold working, hot working is particularly suitable for mass production, but requires higher equipment costs.

On the other hand, heating (or soaking), which is a step before hot working, is performed as a slab or billet.

Therefore, in the hot working (rolling) step, each slab or billet is worked (rolled) intermittently.

The time from the end of one piece of rolling to the next rolling is a major factor that determines the loss time of the rolling line.

Instead of intermittent rolling of slabs or billets one by one, if the slabs or billets are joined before rolling or in the middle of multi-stage rolling, the rolling loss time will be reduced accordingly, and the amount of rolling per degree time will be reduced. increases.

As a result of various studies for the above purpose, the inventors found that
This method has been developed to achieve continuous rolling.

When manufacturing plate-shaped products by sequentially and continuously hot rolling steel billets, the trailing end of the preceding rolled material and the leading end of the following rolling material are rolled in order to improve productivity and yield. A hot continuous rolling method has been devised in which rolling is continued after overlapping, thereby joining both sides of the rolled material and continuously supplying the rolled material.
As shown in , both sides of the overlapping part of both materials require tack welding, and the scale plane of the overlapping part of both materials is less than 40 μ on both sides, and the joining length is equal to or longer than the width of the board. The length requires a solid joint first.

It is necessary that the steel be rolled at a reduction ratio of 30 or more.

. To avoid this, the current method requires a running welder for tack welding of the overlapping parts, and it is also necessary to control the scale thickness of the overlapping parts. This is disadvantageous in terms of yield.

In addition, there are various problems in subsequent rolling, such as the initial rolling requiring a rolling reduction of 30 coefficients or more and the load capacity of the rolling mill being large, requiring large-capacity equipment.

The present invention has been made to advantageously solve the above-mentioned problems, and its feature is that the conventional method has improved rolling stability (for example, the phenomenon that the rolled material warps in the direction of winding around the rolls). Instead of the tack welding method that is used to prevent the welding from occurring, it is possible to use a rod-shaped or plate-shaped material that has a strength higher than the hot strength at the rolling temperature of the rolled material at the joining area. The continuous rolling method is characterized in that rolling is performed in a state in which the joined portions of the rolled and measured rolled materials are temporarily secured.

That is, in the conventional method, for example, between a rough rolling mill and a finishing mill for steel billets, as shown in FIG. They were overlapped by a length W of 1 or more, and immediately after that, both side surfaces of the tips of the overlapped portions W were tack welded 3.

On the other hand, as shown in FIG. 2, in the present invention, after the leading end of the trailing material 2 is superimposed on the trailing end of the leading material 1, the strength is higher than the hot strength at the rolling temperature of the rolled materials 1 and 2. A material 4 having a shape represented by a rod or a plate is driven into the overlapping portion W.

Ru.

In this case, as mentioned above, the nail-like material 4 driven into the material to be rolled cannot be driven into the state shown in Fig. 2 unless the hot strength is higher than the hot strength of the material to be rolled, but if the strength is too strong, the following Rolls are scratched during rolling.

Therefore, it is preferable that the material becomes approximately the same strength as it receives heat transfer from the material to be rolled during subsequent rolling.

To further explain this point, the temperature of the intermediate rolled material just before being rolled in the finishing mill is usually 950 to 1050°C.
It is.

In this temperature range, the strength (yield stress) of the intermediate rolled material (copper strip) is 7 to 8 kg/crIL2.

These intermediate rolled materials are overlapped at the tail end of the leading steel strip and the tip end of the trailing steel strip, and in this state, for example, a nail-shaped material having the same alloy composition as the copper strip is driven into the overlapped part. Stop it.

Since the nail-shaped material is driven into the overlapping part of the copper strips at room temperature, its strength (yield stress) is about 25 kg/mrIL2,
It has sufficient strength.

Although the temperature of the nail-shaped material driven into the overlapping portion of the steel strip increases due to heat transfer from the copper strip, it has sufficient strength until the rolling of the overlapping portion progresses several passes.

After the overlapping portion has been sufficiently rolled, the nail-like material reaches the same temperature as the steel strip, and rolling proceeds without applying any impact load to the rolls.

For this reason, the nail-like material to be driven into the overlapping portion of the copper strips is preferably made of the same material as the steel strip or a material with physical properties similar to those of the steel strip.

In addition, the above-mentioned material may be implanted by a method that utilizes the energy of a gunpowder explosion, or by a method that utilizes the compressive force of compressed air or compressed gas, but the key is to implant the material in an extremely timely and instantaneous manner. There is a need for a method that can do this.

In this case, the driving depth of the above-mentioned material may be such that it penetrates the rolled materials 1 and 2 as shown in FIG. 2, or as shown in FIG.
It may protrude from the upper or lower surface as shown in FIG.

In this case, the number of inserts should be at least the minimum number necessary to ensure the stability and stability of rolling of the material to be rolled, so the number will vary depending on the shape of the material to be rolled, but for example, if the number is 30tnrnpj and the width is about 1000mm. 2-4 for hot strips
A book or so is required.

When the overlapping parts are temporarily fixed by the above method and joined by subsequent rolling, (1) In the conventional method, the thickness of the scale existing on the joint surface is 40
However, in the method of the present invention, the instability of the joint surface during subsequent rolling is restrained by the strength of the implanted material itself, and the joint surface is temporarily fixed, so it is not necessary to
There is no need to make the scale smaller than μ.

This is due to the fact that the scale is easily peeled off due to the impact caused by implantation.

In this case, it is more effective to use a scale peeling accelerator on the joint surface.

(2) In the conventional method, the overlapping amount W was required to be more than % of the board width, but according to the method of the present invention, as described in (1), the overlapping amount W is more than % of the board width by tacking with the driving material. The amount is not necessarily necessary and depends on the thickness of the material to be rolled, but it may be 2 m
For steel slabs with a thickness of about i, it is possible to stack about 20 to 50 plates.

(3) In the conventional method, temporary fixing was performed by tack welding, which required a welding machine between runs, but the method of the present invention does not require expensive welding machines between runs, etc., and temporary fixing can be done instantly. It is possible.

(4) In the conventional method, after tack welding, it was necessary to roll with a reduction ratio of 30% or more in the subsequent rolling, but in the method of the present invention, tack welding with the pouring material is not necessarily performed at an initial rolling reduction of 30% or more due to the presence of strength. There is no need to apply a reduction of more than 100 degrees, and it is possible to join even if the total reduction is 10 to 20 degrees as long as the total reduction is 5 times or more.

Therefore, it has many advantages, such as requiring only a small rolling facility.

Another feature of the method of the present invention is that it is possible to easily join steel materials while they are running.

The method of the present invention is applied to external AI of steel plates, long steel products, etc.

It is effective when applied to continuous hot rolling of Cu, Zn, their alloys, and other non-ferrous metals.

Next, embodiments of the present invention will be described in detail using steel plate strip rolling as an example.

Before hot rolling, the slab is heated to the lowest temperature that takes into account constraints on the material and rolling operations.

The slab taken out from the heating furnace is immediately rolled through rough rolling and finish rolling while maintaining a predetermined temperature.

In order to maintain heat and improve productivity, it is removed from the heating furnace.
The steel is constantly running until it is wound into a coil.

Therefore, between slabs or at an intermediate stage of rolling, for example between finish rolling and rough rolling.

In the case of bar joining, there is no practical value unless there is a method that allows easy joining of the front and rear head and tail parts while the vehicle is running or during a very short stop.

FIG. 4 shows an embodiment of the present invention.

Arrow a indicates steel material D1. It shows the direction of movement of D2.

The advancing speed of the tail portion of the steel material D8 under specified rolling conditions is measured and observed with an infrared measuring device B, and the advancing speed of the steel material D2 is controlled by controlling the speed of the roller R8.

X-ray measuring device X1. Dl in X2. Measure and control the D20 overlap, and drive the steel nail from the nailer A to the steel material D1. D20
Drive into the overlapped part.

The mechanism of the nail driver A may use explosives such as a dry bit for thrust, or may use high pressure gas.

The key is to overlap and join them in a very short time using one or more steel nails, and then to engage the rolling mill R2 and roll them.

S in the figure is a scale remover coating device that applies a scale remover containing glass powder, metal oxide powder, etc. as a main ingredient to the tail of the D1 steel material to promote scale releasability, and then nails are applied. , joining, rolling.

By rolling, the scale is easily broken and the adhesive force between the slabs is significantly increased.

Next, examples of the present invention will be given.

A low carbon steel slab with a thickness of 250 mTl, a width of 1200 m7K, and a length of 10 m is rough rolled to a thickness of 30 rran on a normal hot rolling line, and then finished rolled to a thickness of 2 to 3 mm.
mm hot-rolled sheet, but in that case, between rough rolling and finishing rolling, the trailing end of the leading material and the leading end of the trailing material are rolled at 1007 mm in the length direction? +! After the sheets were overlapped in width, four dry pits (diameter 2 mm) were hammered into a state as shown in Fig. 2, and finish rolling was performed.

In this case, the first pass of the finishing mill was reduced by 30 mm,
Subsequent rolling was performed with the same reduction distribution as in the conventional method.

As a result, the joining of the preceding material and the succeeding material could be performed with no inferiority to the conventional method.

As a result, as mentioned above, according to the method of the present invention, there is no need for scale control, and the number of overlapping parts can be greatly reduced, which further improves the yield and enables completely continuous operation, which significantly improves productivity. .

It has also been found that the equipment investment is extremely low since it can be done without using welding material between the runs.

The tacking method according to the present invention is extremely effective for pressure bonding by rolling as in this method, but it is also effective for pressure bonding by pressing with a press or the like in addition to rolling.

In addition, the end face of the overlapping part does not necessarily have to be cut perpendicularly to the axis of the steel billet across the width direction, and may be cut obliquely at a predetermined angle to the axis of the billet, or it may be cut as is without being cut. The shape of the end face does not impair its function.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the conventional method of joining rolled materials, Figure 2
The figure is an explanatory diagram of the joining method in the method of the present invention, Figure 3a,
b and c are explanatory diagrams of the joint portion, respectively, and FIG. 4 is an explanatory diagram of an embodiment of the method of the present invention. 1.2...Rolled material, 3...Tack welding part, 4...Nail-like material, Dl, D2...Steel material, R
1, R2... Rolling machine, R3... Conveyance roller, A... Nailing machine, S... Scale remover coating device.

Claims (1)

[Claims] 1. When obtaining a steel strip by hot rolling, before the copper strip enters the finish rolling process, the trailing end of the leading steel strip and the leading end of the trailing steel strip are overlapped, and the overlapping If. A method of heating a copper strip characterized in that a nail-like material having a strength greater than that determined by the material and temperature of the copper strip in the overlapped portion is temporarily fixed by driving into the overlapped portion, and rolling is performed continuously. Infinite continuous rolling method. 2 Overlap of the rear end of the leading steel strip and the tip of the trailing steel strip. Prior to driving the nail-like material into the mating part, the nails are overlapped,
2. The method for hot endless continuous rolling of a copper strip according to claim 1, characterized in that after applying a scale remover to the contacting surfaces, a nail-like material is driven in for temporary fixation, and finish rolling is continuously performed. 3. Prior to driving the nail material into the overlapping part of the rear end of the leading steel strip and the leading end of the trailing steel strip, scales on the overlapping and contacting surfaces are mechanically polished or scarfed with oxygen gas. 2. The method of hot endless continuous rolling of a copper strip according to claim 1, wherein after removal, a nail-like material is driven in for temporary fixation and finish rolling is continuously performed.