JPH0777643B2 - Hot continuous finish rolling equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application The present invention relates to a hot continuous finishing rolling facility for thin slabs obtained by continuous casting.

(B) Conventional technology Usually, as a base material for cold-rolled steel strips for automobiles with a thickness of 0.6 to 0.8 mm,
A hot rolled steel strip with a thickness of 3 to 5 mm is used. When manufacturing this hot-rolled steel strip, first, use a continuous casting facility to obtain a thickness of 200-300.
mm, a slab with a width of 1000 to 2000 mm is produced, and this slab is cut into a length of about 10 m in a continuous casting line. The cut slab is conveyed to the hot rolling process, heated to a predetermined temperature (1050 to 1200 ° C) in a heating furnace, and then subjected to continuous rolling or reversal rolling with several rough rolling mills to obtain a thickness. 30
It is rolled to about 50 mm and is further rolled into a hot rolled steel strip with a thickness of 3 to 5 mm by a continuous finishing mill with 6 to 7 stands.

By the way, in recent years, due to the development of continuous casting technology for thin slabs, which is different from ordinary continuous casting, the thickness is reduced to a fraction of the conventional thickness (20 ~
50mm) thin slabs have been manufactured. as a result,
In the case of producing the above hot-rolled steel strip, the conventional hot-rolling rough rolling step is not required, and the thin slab can be directly supplied to the hot-rolling finish rolling step, which brings about a great effect in reducing the equipment cost.

Furthermore, in order to manufacture a cheaper hot rolled steel strip by using this thin slab, the equipment cost is lower than that of the conventional hot rolling finish rolling equipment, and moreover, the heating energy before rolling can be reduced in terms of energy saving. It is desired to develop a new hot rolling finishing rolling facility that can be small.

As the above new system hot rolling finish rolling equipment, for example, JP-A-61-5
Some are disclosed in Japanese Patent No. 6708.

This continuous hot rolling equipment train will be described with reference to FIG.
20 to 50 cast from thin slab continuous casting equipment 5 (for example, thin slab continuous casting equipment disclosed in JP-A-58-167060)
The hot-thin slab 2 having a thickness of mm has temperature unevenness in the width direction or the longitudinal direction, and the soaking furnace 6 equipped with a simple heating device
Correct with. The soaking furnace 6 also serves to prevent the temperature of the thin slab 2 from decreasing in order to secure the rolling temperature. Next, after the thin slab is reduced to a predetermined plate width by the width reduction device 7 and the scale of the surface is dropped by the descaler 8, the hot-rolled steel having a thickness of 3 to 5 mm is hot rolled by the hot rolling reduction machine 9. Make a belt. The rolled material is then cooled to the target winding temperature in the cooling zone 10 and the winding machine 12
Is wound up in. A running cutter 11 is provided on the entrance side of the winder 12, and cuts a rolled material that is continuously rolled into a predetermined length and alternately winds it on two winders.

Strong hot rolling mill 9 provided in this continuous hot rolling facility
Is, as shown in FIG. 5, a pair of rolling indenting rolls 14a,
14b double roll indenting roll structure 13 and a pair of small diameter work rolls 17a, 17b and a pair of backup rolls 18a, 18b backup roll drive type multiple high-pressure reduction roll structure It has a compact structure in which 16 and 16 are assembled in a common housing 19. In addition, the rolling indenting rolls 14a and 14b and the small diameter work roll 17
Roller guides 15a and 15b for preventing buckling between a and 17b
Is installed.

The thin slab 2 with a thickness of 20 to 50 mm is used for the rolling and pushing rolls 14a and 14b.
Rolling with a rolling reduction of about 50% and pushing force (compressive force)
Are continuously loaded to the small diameter work rolls 17a, 17
It is rolled to a predetermined thickness of 3 to 5 mm at a rolling reduction of about 80% by the multiple-type strong reduction roll structure 16 having b.

When the casting speed of the thin slab is high, the rolling speed is also high, and therefore, the time required for the rolled material to reach the inlet side of the high-pressure reduction roll structure 16 from the outlet side of the rolling push roll structure 13, namely, , The cooling time also becomes shorter. At this time,
As shown in FIG. 6, a rolling mill row 9'in which the rolling push roll structure 13 and the strongly reducing roll structure 16 are incorporated in separate housings 20 and 21 is a rolling mill in which both roll structures are incorporated in the same housing. It is used instead of 9.

The features of the rolling equipment trains described above are that even if the casting speed of thin slabs (about 6 to 15 m / min), which is a fraction of the speed of the rolled material on the side of the conventional hot rolling finishing mill train, is significantly reduced. By performing rolling, the rolling temperature can be secured without reheating, and thin slabs can be rolled into hot-rolled steel strip in the same line as the continuous casting equipment, and the slab winding, rewinding device, reheating furnace, etc. No additional equipment is required, which is very inexpensive and energy saving.

However, it was revealed by the subsequent casting test or the strong reduction rolling test that this equipment train had the following defects.

The first drawback is that the production rate of hot-rolled steel strip cannot be produced due to the limitation of the casting speed. With the current thin cast continuous casting technology, the casting speed can be increased even in thin cast continuous casting due to operational reasons such as breakout during casting and quality of the cast such as deterioration of cast surface and internal defects. It cannot be made so fast, and the limit is [cast thickness (m)] × [casting speed (m / min)] = 0.3 for a 20-50 mm thick cast piece.

This means that for a 1200 mm wide slab, the production amount of approximately 170 ton / hr is the upper limit for one thin slab continuous casting facility,
Currently about 1/4 of the production capacity of hot rolling finishing rolling equipment (about 8-9
10,000 tons / month). Therefore, in the thin casting continuous casting equipment 5 as shown in FIG.
The continuous hot-rolling equipment line equipped with is the cheapest for small-scale production, but for medium-scale production of 100,000 tons / month or more or large-scale production such as the current hot rolling finishing rolling equipment. , Thin cast continuous casting equipment 5 as well as strong rolling mill 9
However, it is not necessarily an inexpensive hot-rolled steel strip manufacturing facility.

Next, the second drawback is that the rolling material is seized on the roll when the high-pressure reduction rolling is performed, and the high-pressure reduction rolling has a limit. In order to realize the hot strong reduction rolling, the above-mentioned JP-A-61-567 is used.
As described in Japanese Patent Publication No. 08, it is necessary to use an indirect drive multiple rolling mill having a small-diameter work roll from the viewpoint of facility strength. As a measure against slip between rolls, the equipment must be equipped with a buckling prevention device so that the pushing force can be applied even when rolling thin slabs.

By the way, when the present inventors carried out a hot strong reduction rolling test, it was found that even if a normal carbon steel rolled material is seized on a work roll, if the strong reduction rolling with a certain reduction ratio or more is performed in one pass, It became clear that not only equipment strength limitation, poor biting, and occurrence of slip between rolls but also seizure between rolling material and roll should be taken into consideration as the limit of strong reduction rolling. The occurrence of seizure of the rolled material is affected by the ratio of the incoming plate thickness to the outgoing plate thickness (reduction ratio), the rolling pressure between the rolled material and the work / roll, the incoming rolling material speed, the work / roll surface temperature, etc. . In particular, the reduction ratio (or reduction ratio) at the time of seizure decreases as the speed of the incoming rolling material increases, and in order to carry out strong reduction rolling with a reduction ratio of about 70% (reduction ratio = 3.3). It became clear that it is necessary to limit the speed of the incoming rolled material. Therefore, in the rolling equipment for performing the strong reduction rolling in the second pass as shown in FIG. 5 or FIG. 6 described above, the entry side rolling material speed in the second pass increases according to the reduction ratio in the first pass. Therefore, if the rolling material speed on the inlet side of the rolling equipment becomes faster, seizure will occur and the limit of the strong reduction rolling will be determined, and the strong reduction rolling with the reduction rate of about 70% performed in the second pass becomes impossible.

As described above, when the thin cast continuous casting equipment 5 as shown in FIG. 4 is equipped with an equipment capable of inline strong rolling, the hot rolling of the production scale of 100,000 tons / month or more is achieved. As a steel strip manufacturing facility, it is not always an inexpensive facility,
For medium and large-scale production where the production volume exceeds 100,000 tons / month, several thin slab casting equipment equipped with a thin slab winding device are installed, and hot rolling of one hot finish rolling equipment is performed. The equipment for manufacturing the belt is cheaper. Further, in the rolling equipment for performing the strong reduction rolling after the second pass as shown in FIGS. 5 and 6, the higher the production rate, the higher the rolling speed. Due to the rolling reduction due to seizure of the material, the rolling reduction per pass cannot be made so large that a large reduction in equipment cost cannot be expected compared with the conventional hot rolling finishing rolling equipment. Therefore, in order to realize a large reduction in equipment cost, a compact hot rolling finishing rolling equipment that requires a smaller number of rolling mills than a conventional rolling equipment is required as a rolling equipment capable of performing high reduction rolling even in high production.

(C) Problems to be Solved by the Invention The problems to be solved by the present invention are to obtain an inexpensive hot continuous finishing rolling facility that can be applied to medium-scale or large-scale production of thin slabs with a thickness of 20 to 50 mm. Especially.

(D) Means for Solving the Problems The hot continuous finishing rolling facility of the present invention was installed in a backup roll-driven multiple horizontal rolling mill having a small-diameter work roll, and an inlet side of the horizontal rolling mill. A rolling device comprising a pinch roll for pushing the rolled material and a roller guide for preventing buckling of the rolled material, which is installed between the horizontal rolling mill and the pinch roll, is installed on the first stand of the hot continuous finishing rolling mill train. The installation solves the above problems.

The rolled material may be a continuously cast thin slab, or may be rewound from a coil of the thin slab.

(E) Operation In the hot continuous finishing rolling facility of the present invention, a backup roll driving multiple strong reduction mill having a small diameter work roll provided with a pinch roll for pushing force and a roller guide for preventing rolling material buckling. Is installed as the first horizontal rolling mill of the hot rolling finishing continuous rolling mill train, the following effects are obtained.

Since the pressing force load necessary for high reduction rolling is realized by the light reduction of the thin slab by the pinch roll, the speed of the rolled material does not change much before and after the pinch roller. further,
Since the high-pressure reduction rolling mill is installed on the first horizontal rolling mill of the hot rolling finishing continuous rolling mill line, the speed of the incoming rolling material during high-pressure reduction rolling is almost the same as the thin slab speed supplied to the hot rolling finishing rolling facility. Equally, it is a low speed, strong rolling can be performed without causing seizure of the work roll and the rolled material.

By carrying out the strong reduction rolling, a hot-rolled steel strip can be obtained with a smaller number of rolling mills as compared with the conventional hot-rolling finish rolling equipment including a rolling mill having 6 to 7 stands, and an inexpensive hot-rolling equipment can be realized.

(F) Example Next, with reference to FIG. 1, an example of the hot continuous finish rolling facility of the present invention will be described. In FIG. 1, the same reference numerals as in FIG. 4 indicate the same elements.

Thin slab 20 to 50 mm thick hot slab 2 cast from continuous casting equipment 5 is cut into a predetermined length by a slab cutting machine 22, and a thin slab is taken up by a winder 23 installed on the outlet side. Wind up 2. The rolled thin cast piece is subjected to a hot continuous finishing rolling facility 10 by a thin piece coil carrying device 24 equipped with a heat retaining device to prevent a temperature drop.
Transported to 0.

On the inlet side of the hot continuous finishing rolling facility 100, a slab uncoiler 25
Is installed and the thin slab coil is rewound and supplied to the hot continuous finish rolling mill train 110. The rewound slab is reduced to a predetermined plate width by the width reduction device 7, the surface scale is reduced by the descaler 8, and then the slab is supplied to the hot continuous finish rolling mill train 110 of the present invention.

Rolling equipment 120 on the first stand of the hot continuous finishing mill train 110
To provide. The rolling device 120 will be described in detail later with reference to FIG. 2, but a pinch roll 121 for pushing force, a roller guide 122 for preventing rolling material buckling, and a backup roll drive quadruple having a small diameter work roll. It consists of a high-pressure rolling mill 123 of the type.

Strong reduction rolling is performed by the high reduction rolling mill 123, and further, a backup roller driven quadruple rolling mill 13 installed near the exit side.
The hot rolling is performed to a predetermined thickness (1.5 to 5 mm) by the finishing mill 140 of 0 and the final stand. The rolled hot-rolled steel strip S is cooled to a predetermined temperature by the cooling zone 10 and then cut into a predetermined length by the running cutting machine 11, and the winding machine 12
To be wound up.

The rolling apparatus 120 capable of performing strong reduction rolling in the hot continuous finish rolling facility 100 of the present invention will be described in detail with reference to FIG. The rolling apparatus 120 has small-diameter work rolls 125a and 125b as a measure for reducing the high rolling load at the time of strong reduction rolling,
Further, it has a quadruple rolling mill driven by backup rolls 126a and 126b. In order to transmit the high torque required for the strong reduction rolling, the backup rolls 126a and 126b are driven to drive the high reduction rolling mill 16 (No. 5) described in the above-mentioned JP-A-61-56708.
Similar to the one shown in the figure), this is a rolling mill capable of strong reduction from the standpoint of equipment strength. Also, measures against bite failure during high-pressure rolling and backup roll 126a and work roll during indirect drive
As a measure against slipping with 125a, a pinch roll 121 for pushing the rolling material is installed on the inlet side of the high reduction rolling mill 120, and a pinch roll 121 is provided to prevent buckling of the rolling material when the pushing force is applied. A roller guide 122 is installed between the sheet and the high reduction rolling mill 120.

Here, as shown in FIGS. 5 and 6 (Japanese Patent Laid-Open No. 61-56708).
No.) and the difference from the strong rolling mill. As described in the description of the prior art, the strong rolling reduction limit is determined by the rolling reduction limit due to seizure between the work roll and the rolled material, in addition to the rolling reduction limit considered from the viewpoint of equipment strength. The occurrence of seizure that occurred when a hot reduction rolling test was performed using low carbon steel was also observed. The rolling test is 900 mm hot steel backup roll with a width of 80 mm and a thickness of 15 mm, the roll diameter is 250 mm,
Work roll diameter 80mm backup roll drive 4
A heavy rolling mill was used to perform strong reduction rolling with a reduction rate of 80% (reduction ratio of 5). Especially, in this test example, the speed of the rolled material on the incoming side is about 2 m / m.
We performed unlubricated rolling at a low speed of in.

As can be seen in this test example, when 1-pass strong reduction rolling with a very large reduction ratio is performed, the rolled material and the work roll are seized, and the surface of the rolled material is significantly damaged, which is large in product quality. It becomes a problem. Further, the seizure also significantly damages the surface of the work roll, making subsequent rolling impossible and a serious problem in operation. For this reason,
From the viewpoint of preventing seizure, it is necessary to limit the rolling reduction per pass.

Further, when the present inventors conducted a strong reduction rolling test, it was found that the occurrence of seizure depends on the speed of the incoming rolling material. The test results are shown in FIG. The rolling equipment used in this test is a two-stand continuous rolling equipment as shown in FIG. The rolling mill 20 on the incoming side is a double rolling mill incorporating a roll with a diameter of 300 mm, and the rolling mill 21 on the outgoing side is a backup roll 18a, 18b with a diameter of 250 mm and work rolls 17a, 17b with a diameter of 100 mm. It is a backup roll drive quadruple rolling mill incorporating

Since the occurrence of seizure depends on the roll material, it is used in conventional hot rolling and finishing rolling equipment. Tests were performed using cast iron type rolls (carbon content 3%) for the work rolls 14a, 14b, 17a, 17b. The test piece is made of low-carbon steel with a thickness of 16 mm × width of 100 mm × length of 1,500 mm.
Rolling start temperature is set to 1050 ℃ and thickness is 7.5m at the entry side rolling mill 20.
After rolling down to m, non-lubricating strong rolling was performed by the exit rolling mill 21, and the occurrence of seizure was observed.

As shown in FIG. 3, the rolling reduction at the time of seizure decreases as the inter-stand rolling material speed (the incoming rolling material speed of the outgoing rolling mill 21) increases.

The test results are used to compare the reduction limits of the strong reduction mill 9 shown in FIG. 5 or 6 and the rolling apparatus 120 of the present invention shown in FIG. In the case of the rolling mill 9 shown in FIG. 6, when rolling with a reduction ratio of 50% (reduction ratio 2) is performed in the first pass, strong reduction rolling is performed at the first pass entry side rolling material speed of 10 m / min. The speed of rolled material on the pass side is 20m / min.
From the figure, the second pass maximum reduction ratio is 3 from the viewpoint of preventing seizure. Therefore, the total reduction ratio of the first pass and the second pass is 6. On the other hand, when the rolling apparatus 120 of the present invention shown in FIG. 2 is used, the rolling speed of the first pass entrance side is 10 m / min.
In Fig. 3, rolling with a reduction ratio of 3.5 is possible. Second
In the pass, the incoming rolling material speed is 35 m / min. But,
Estimated from the test results, the reduction rate is 60% (reduction ratio 2.5)
Rolling to some extent is possible. Therefore, the first pass, the second
The total reduction ratio of the pass is 8.75, and the rolling facility of the present invention can perform strong reduction rolling with a reduction ratio of 1.46 times.
Compared with the rolling mill shown in No. 6708, it is possible to realize an inexpensive hot rolling finishing rolling facility with fewer rolling mills.

When the hot continuous finish rolling facility 100 of the present invention is installed offline in the thin slab continuous casting facility 5, the thin slab supply rate to the rolling facility must match the casting speed of the thin slab continuous casting facility. Moreover, the hot rolling steel strip production capacity of the rolling equipment is not affected by the moving time of the thin slab continuous casting equipment. Therefore, the hot strip production capacity can be increased by a factor of 2 to 3 as compared with the thin cast continuous casting in-line rolling facility shown in FIG.

Further, in the equipment for performing the strong reduction rolling in the second pass as shown in FIG. 5 or FIG. 6, the rolling speed in the second pass is higher than that in the first pass, and moreover, it is the strong reduction rolling. The power of the second-pass drive motor is much higher than that of the first-pass drive motor, and it is necessary to limit the rolling speed due to the manufacturing limit of the motor. In the rolling equipment of the present invention, since the strong reduction rolling is performed in the first pass at which the rolling speed is slow, the power of the drive motor does not become so large. Also in this respect, it is understood that the rolling equipment of the present invention is more advantageous for the hot-rolled steel strip manufacturing equipment having a high production amount.

(G) Effect Since the hot continuous finish rolling facility of the present invention can perform the strong reduction rolling in the first pass, the strong reduction rolling can be performed without causing seizure between the rolled material and the work roll. The rolling line can be simplified, and a thin slab with a thickness of 20 to 50 mm produced by a thin slab continuous casting facility can be rolled into a hot-rolled steel strip with inexpensive equipment investment. In addition, since the continuous rolling equipment is installed offline in the thin slab continuous casting equipment, the hot-rolled steel strip production amount is not affected by the casting speed and the casting equipment operation time, and high production is possible.

[Brief description of drawings]

FIG. 1 is a schematic explanatory view of a hot continuous rolling facility for thin cast pieces according to the present invention. FIG. 2 is a schematic explanatory view of the hot strong reduction rolling mill installed in the hot continuous finish rolling mill train of the present invention. FIG. 3 is a graph showing rolling test results. FIG. 4 is a schematic explanatory view of a conventional hot continuous finishing rolling facility for thin cast pieces. FIG. 5 and FIG. 6 are schematic explanatory views of a conventional hot strong reduction rolling facility. 2 …… Thin cast piece, 5 …… Thin cast piece continuous casting facility 6 …… Soaking furnace, 7 …… Width reduction device 8 …… Descaler, 9 …… Hot rolling reduction machine 10 …… Cooling zone, 11 …… Short-cutting machine 12 …… Winding machine 13 …… Rolling and pushing roll assembly 14a, 14b …… Rolling and pushing roll 15a, 15b …… Roller guide 16 …… Strength reduction roll construction 17a, 17b …… Workpiece・ Rolls 18a, 18b …… Backup rolls 19,20,21 …… Rolling mill 100 …… Hot continuous finishing rolling equipment 110 …… Hot continuous finishing rolling mill row 120 …… Rolling equipment 121 …… Pinch roll 122 ...... Roller guide 123 …… High reduction rolling mill 130 …… Rolling mill, 140 …… Finishing rolling mill

 ─────────────────────────────────────────────────── --- Continuation of the front page (72) Inventor Takayuki Kudo 5-15 Kitahama, Higashi-ku, Osaka City, Osaka Prefecture Sumitomo Metal Industries, Ltd. (72) Inventor Shigeharu Ochi 5-2 Sokai-cho, Niihama-shi, Ehime Sumitomo Heavy Industries Machinery Industrial Co., Ltd. Niihama Works

Claims (3)

[Claims] 1. A backup roll driving multiple horizontal rolling mill having a small diameter work roll, a rolling material pushing pinch roll installed on the inlet side of the horizontal rolling mill, the horizontal rolling mill and the pinch roll. A hot continuous finishing rolling facility, characterized in that a rolling device comprising a rolled material buckling prevention roller guide installed between the two is installed at the first stand of the hot continuous finishing rolling mill train. 2. The rolling facility according to claim 1, wherein the rolled material is a thin cast piece continuously cast. 3. The rolling facility according to claim 1, wherein the rolled material is rewound from the coil of the thin slab.