JPH0763724B2 - Method and apparatus for continuous hot rolling of hot billet - Google Patents

Description

The present invention relates to a method and apparatus for continuous hot rolling of hot billet,
In particular, the present invention relates to a continuous hot rolling method and apparatus including a step of joining hot steel pieces in a continuous hot rolling step.

[Background of the Invention]

FIG. 1 shows a layout of a general conventional hot strip mill.

No. 1 is the No. 1 rough rolling mill, which is usually reversible. No. 2 is a No. 2 rough rolling mill, which is often a unidirectional rolling mill. Reference numeral 3 is a clipper that also cuts the leading end or the trailing end of the strip 8 or 9 which is a hot steel strip provided on the entry side of the finishing rolling mill group 4. Reference numeral 5 is a looper provided between the finish rolling mills, and 6 is a pinch roller provided on the inlet side of the down coiler 7 which is a winding machine. 10, 11, 12, and 13 are roller tables, respectively.
The finish rolling mill group 4 is usually composed of 5 to 7 strips, and the strips are rolled over all the finish rolling mills at the same time. However,
Rolling is performed for each slab, or, on the output side, for each coil, intermittently. Therefore, the leading plate and the trailing end are removed for each slab, which causes many problems. This problem disappears if many slabs are combined into one long slab. The reason why this is not realized now is as follows. That is, when the slab is manufactured by the slab mill, the size of the slab is limited to the size of the steel ingot.
There is a need for a method of economically joining materials with a thickness of around 0 mm in a short time, but this is difficult and has not been realized yet.

On the other hand, in continuous casting, infinitely long slabs can be obtained practically, but the production amount of one strand of continuous casting is 1/3 to 1/4 of the production amount of hot strip mill. Slabs must be supplied alternately from a 3-4 strand continuous casting facility for one unit, and there is no choice but to cut the continuous slabs with a good break into appropriate lengths and supply them to the hot strip mill. .

However, if the slab is made continuous, the following effects can be expected.

(1) Miniaturization of equipment and energy saving a) There is no need for biting and squeezing due to continuity, so there is no need to increase the work roll diameter for this reason for biting performance.
(Reduction amount restriction D _W : Work roll diameter, μ: Mass coefficient between roll and material) b) Since the impact torque generated at the time of biting and bottom removal is eliminated, the drive system, and therefore the work roll diameter, can also be made smaller.

c) In hot rolling, recently, oil lubrication aims to extend roll life and reduce rolling load and rolling power, but it is necessary to perform oil draining to prevent biting failure when threading the threaded strip. You have to stop refueling for some time, and
A complicated oil drainer must be installed. In the case of a continuous slab, these are unnecessary and sufficient oil lubrication can always be performed.

Therefore, the rolling mill can be made smaller.

Due to the reasons a), b), and c), the work roll diameter can be greatly reduced, and due to the reduction of the rolling load by itself and the rolling load reduction effect of oil lubrication, the reinforcing roll diameter can also be reduced. The entire machine can be downsized. It is also possible to reduce the number of stands and reduce the equipment cost by increasing the reduction per stand without downsizing.

Also, since the rolling power is almost proportional to the square root of the work roll diameter, for example, the work roll diameter should be 5%, which is 64% from the conventional 800 mm position.
If it is set to 12 mm, the rolling power will be saved by 20%, and the drive motor of 10,000 kW per stand can save 2000 kW.

Generally, when the diameter of the work roll is reduced in this way, the lateral rigidity of the work roll decreases, the axial deflection of the work roll increases due to changes in rolling load and changes in the strip width, and the strip shape of the product strip (flatness). ) Is aggravated by the fact that there is a known roll bending (work roll or intermediate roll) for a six-high rolling mill that can move the intermediate roll axis and a four-high rolling mill that moves the work roll axis. You can respond by acting.

(2) Improvement of quality and yield In the conventional rolling method, tension is not applied to the strip when the stripping of the finishing rolling mill is performed, and tension is applied in other cases.
The thickness and width of the plate changed, and bending was likely to occur because the front and rear ends were tensionless, which reduced the yield quality. This can be resolved by making it continuous. Furthermore, in order to minimize the difference between tensionlessness during striping and tailing, it was inevitable that the tension was low even during normal rolling, but there was no need for continuous tensioning. In addition to the reduction of rolling load, strong reduction, and rolling of thinner material, if necessary, tension can be consciously controlled to control strip width.

As described above, the continuous process has a great economic effect, but the realization thereof has been extremely difficult. We have already realized the continuity of cold strip mills (cold strip mills). This is to achieve continuity by joining the tail end of the preceding coil and the tip of the succeeding coil by welding, but since the plate is thin and at room temperature, a stripper propeller is provided between the rolling mill and the welding machine. While the stripper is supplied from the looper to the rolling mill and the rolling is continued, the welding machine can perform welding in a stopped state. In contrast, the hot rolling equipment has a slab thickness of 200 mm.
The thickness is 30 to 50 mm on the front and back and also on the entry side of the finish rolling mill, making it difficult to form loops.Also, even if it is possible, the rolling time is short, so the welding time between slabs can be short. is there. By the way, when cold, the rolling time for one coil is 3
While the welding time is ˜5 minutes and the welding time is 1 to 2 minutes, the rolling time for one slab is 1 minute or less at the hottest. Therefore, if the welding method is used to achieve continuity, it will not be realized unless the welding is completed in a few seconds in the running welder.

However, as a conventional continuous hot rolling method, the method disclosed in JP-A-48-6715 is used.
In "Jointing of heating materials and continuous rolling method" proposed in No. 9, the head of the subsequent unit material is contacted while approaching the entrance of the rough rolling mill and following the progress of the tail of the heating material during rough rolling. While joining, the periphery of the contact surface is joined by electromelting or pressure cutting,
This joining method is successively continued to perform continuous rolling.

However, electrolysis requires time in minutes, for example,
The material progresses at a speed of 30 m / min, and even if the welding time is 1 minute, it is necessary for the welding machine itself to move about 30 m, which poses various problems in terms of space and mechanical structure.

On the other hand, whether it is pressure welding or simply welding the end portions together, it takes a long time for joining depending on the cross-sectional shape and the scale adhesion state, the joining reliability is low, and during hot rolling in the post process. To
It is likely to be separated.

On the other hand, according to the "hot rolling method for billet" proposed in Japanese Patent Laid-Open No. 51-59748, the hot strips are successively hot-rolled in sequence, in advance, at the front end and the rear end in the longitudinal direction. Shearing the steel piece in the width direction, shearing is performed so that the angle at which the sheared end face intersects the steel piece becomes a constant angle (20 ° to 85 °), and this sheared surface is descaled and sheared at the same angle. By rolling while pressing against the trailing end surface of the preceding steel slab, the two steel slabs are pressed against each other and sequentially joined.

However, with this method, the angle at which the sheared end face intersects the billet is determined.
Although it is necessary to perform shearing so as to be 20 to 85 °, it is difficult to obtain such work during rolling, and this is an off-line work before inserting the heating furnace or the heating furnace. Moreover, it is difficult to shear with a high degree of accuracy. Further, in this method, both shearing end faces of the steel slab are pressed into the rolling roll while being pressed, but it is difficult to set the pressing force and the rolling reduction.

[Object of the Invention]

An object of the present invention is to enable welding of the trailing end portion of a preceding hot steel billet and the leading end portion of a trailing hot steel billet in a short time and economically, and to continuously weld these hot steel billets. It is an object of the present invention to provide a continuous hot rolling method and apparatus for hot rolling billets, which realize hot rolling of billets.

[Outline of Invention]

In order to achieve the above-mentioned object, in the continuous hot rolling method of the hot rolled steel billet of the present invention, after being rolled by the rough rolling mill, the trailing end portion of the hot rolled hot steel billet that travels in advance, and the trailing edge Clamping the leading end of the hot-working steel strip running in close proximity, the rear end of the preceding hot-working steel billet running, and the tip of the trailing hot-working steel billet running Cutting each of the parts by advancing the blade along the plate thickness direction of the hot steel slab, cutting the leading end of the hot steel slab that travels in advance, and running after the trailing end. Each of the cut parts at the tip of the hot steel billet is
A step of heating up to a temperature range of 50 ° C to 1450 ° C, and a leading end portion of the trailing hot steel billet to the cutting surface of the trailing end portion of the preceding hot rolling billet The step of pressing and joining the cut surfaces, the step of hot rolling the joined hot steel slab with a finishing rolling mill, and the winding of the hot rolled hot steel slab with a winder It is composed of steps.

That is, by providing the above steps, it becomes possible to weld the trailing end of the preceding hot steel billet and the leading end of the trailing hot steel billet in a short time and economically. The continuous hot rolling can be realized.

Further, in order to achieve the above object, in the continuous hot rolling apparatus for hot billet of the present invention, it is provided between the rough rolling mill and the finish rolling mill, and moves along the traveling direction of the hot billet. In a continuous hot rolling apparatus for hot strips equipped with a possible joining apparatus, the joining apparatus is a carriage mounted movably on a rail extending along the traveling direction of the hot strips. And the joining device, the joining device clamps the trailing end portion of the hot-working steel piece traveling ahead and the tip end portion of the hot-working steel piece traveling behind, respectively, and the preceding traveling The hot steel billet is provided with blades in the vertical direction of the rear end of the hot steel billet and the leading end of the hot steel billet that runs backward, and the blade is provided with a hydraulic cylinder device in the plate thickness direction of the hot steel billet. And a cutting device for advancing along the trailing end of the hot-working steel strip that travels in advance A high-frequency heater that heats and raises each cutting portion with the tip portion, and one of the hot steel pieces that travels in advance and moves, is sandwiched and transferred between the hot steel pieces. And a pressing device that presses the cut surface of No. 1 against the cut surface of the other hot steel slab.

That is, by providing the above steps, it becomes possible to weld the trailing end of the preceding hot steel billet and the leading end of the trailing hot steel billet in a short time and economically. The continuous hot rolling can be realized.

Example of Invention

FIG. 2 shows a hot strip mill which is an embodiment of the continuous hot rolling apparatus for hot billet according to the present invention. In FIG. 2, description of the parts common to the conventional hot strip mill shown in FIG. 1 in the basic arrangement of the equipment is omitted. In the figure, a trolley 20 which is a joining device for joining the trailing end of the preceding hot steel slab 8 and the leading end of the trailing hot steel slab 9 is arranged on the entry side of the finish rolling mill 4. Also, a crop shear 14 and a pinch roller 6 for winding a desired amount of strip of hot steel slab that is joined and continuously rolled by a finish rolling mill 4 on a down coiler 7 which is a winder,
15 is installed on the exit side of the finish rolling mill 4 and on the entrance side of the down coiler 7. FIG. 2 shows the case where strips, which are hot steel slabs, are joined and made continuous on the entry side of the finish rolling mill.
To make the strip continuous, a device capable of joining the preceding and succeeding strips in a short time is arranged on the entrance side of the finishing rolling mill, and the strip moving speed is followed to move a certain short distance. (2.5 m including 5 seconds including cutting and joining) Next, a strip joining method in a short time will be described. To join the strips, there are welding brazing, forging welding, pressure welding and mechanical joining methods, but (1) they must be joined in a short time (within a few seconds).
(Problem of scale generation) (2) During the rolling in the finish rolling mill in the subsequent process, the joining strength must be such that the joining does not come off.

Considering the conditions, flash welding
Although high-frequency induction heating + pressing and pressure welding are used, the welding time is several tens of seconds to several minutes, and there are the following various problems.

That is, since the temperature of the hot-rolling strip itself is about 1000 to 1100 ° C. at the joining position, if pressure welding can be performed at this temperature level, joining without energy consumption is possible.

Therefore, the inventor used a small model (material size: thickness 9 m
m, width 60 mm).

However, it was found that joining was impossible in the test up to pressing force of up to 3 kg / mm ² . Here, the pressing force is 5-10 kg / mm ²
Although it is possible to make it big,
For example, in the case of a material with a thickness of 50 mm and a width of 1500 mm, the pressing load is (50 × 1500) × (5 to 10) = 375 tons to 750 tons, which is very large and the equipment is large, and the hot steel billet itself There is a bend and it is not feasible.

Furthermore, the inventor conducted various tests and examinations with the above model in order to pursue the possibility of the method of
It was confirmed that the combination range (hatched portion) of the heating temperature and the pressing force as shown in FIG. 6 is the joinable region. That is, it is clear that the heating temperature is in the range of 1250 ° C. to 1450 ° C., of which the pressing force must be large on the low temperature side, while the pressing force can be small on the high temperature side.

In short, it is necessary to heat the hot steel billet to a temperature near the melting point of the material and press it as a condition under which joining is possible.

Also, if you select the high frequency power source capacity appropriately (1000 ℃ ~ 1100 ℃) →
The heating and heating time of (1250 ° C to 1450 ° C) can be set to 5 to 20 seconds.

Furthermore, in the hot rolling process in the post-process, the best joining condition is that only the complete bond is bonded to the periphery and only the inside is bonded, which is the best, but the heating time becomes longer and the economic effect (power consumption) and Considering short-time bonding, is effective. Meanwhile, another test (100mm
Perimeter bonding rate (welding) is 30% for thickness x 1400 mm width actual slab)
There is an example where the sheet bar could be rolled without problems. With respect to, due to the surface notch effect, it breaks during hot rolling.

As described above, the peripheral bonding is advantageous from the viewpoints of economical bonding and short-time bonding, and the high frequency heating can be said to be optimal from this point.

According to this method, it is possible to join in a short time of 5 to 20 seconds and in the atmosphere, and continuous hot rolling of steel slabs becomes possible.

FIG. 3 and FIG. 4 show an example of a hot steel strip joining apparatus applied to a hot strip mill, which is an embodiment of the continuous hot rolling apparatus for hot strips shown in FIG. An example is shown.

In FIG. 3, the carriage 20 can travel on the rail 41 so that it can travel in accordance with the moving speed of the billet. The carriage 20 is provided with strip pressing devices 22 and 21 so as to clamp and hold the vicinity of the rear end of the preceding steel piece 8 and the vicinity of the tip of the following steel piece 9, respectively. The strip pressing devices 22 and 21 are provided with the preceding steel strip 8
It is operated by a detection signal from a detection device 62 for detecting the position of the rear end portion and a detection device 61 for detecting the position of the front end portion of the following steel strip 9, and each of the steel strip end portions is respectively moved by the built-in hydraulic cylinder devices 22a, 21a. It is configured to be clamped. Further, the lower tool rests 23 and 24 having the tool 42 and the upper tool rest 2 having the tool 43 are provided between the strip pressing devices 21 and 22.
A cutting device constituted by 5, 26 is arranged, and the upper tool rests 25, 26 are lowered by the operation of the hydraulic cylinder devices 25a, 26a, respectively, and the rear end portion of the preceding steel piece 8 and the transfer steel piece 9 are transferred. Vertically cut the tip of the specified size. Moreover, the upper turret 25, 26 is located below the upper turret 25, 26, that is, at a position below the steel slab.
A pedestal 27 equipped with a hydraulic cylinder device 27a that is operated in synchronization with the descending of 26 is installed.
Applying a certain force to the steel pieces when cutting the ends of 8, 9 and lowering the pedestal 27 as the upper tool rests 25, 26 descend, the steel pieces can be cut reliably and with high accuracy. It is becoming like this.

A motor 31, a rack 32, and a pinion 33 are provided between the lower turrets 23 and 24, as shown in FIG.
The claw extruding device 30 is installed which moves in a horizontal direction at a right angle to the traveling direction of the steel slab as the rack 32 engaged with the pinion 33 by the drive of the. Then, the rear end portion of the steel slab 8 and the tip portion of the steel slab 9 cut by the cutting device are removed to the outside from the traveling line of the steel slab so as not to hinder the next joining work.

Further, after the steel strips 8 and 9 on the carriage 20 are cut with a cutting device, and then the cutting steel strips are removed by the crop extrusion device 30, the trailing end and the subsequent steel strips of the preceding steel strip 8 are removed. High frequency heating device 63 at the tip position of 9 (in this figure, high frequency induction heating device is shown)
Move to the position of, heat up and raise the temperature of the heated billet 1250 ℃ ~
After detecting that the temperature reached 1450 ° C with the same sensor 64, with the preceding steel piece 8 clamped by the clamp cylinder 65,
As shown in FIGS. 4 and 5, a pressing device 35 for pressing and joining the subsequent steel piece 9 to the preceding steel piece is installed. The pressing device 35 includes upper and lower pressure plates 51 and 52 for pressing the succeeding steel strip 9 from above and below, a hydraulic cylinder 36 for adjusting a gap between the pressure plates 51 and 52, and a steel plate which moves in the traveling direction of the steel strip. It is composed of a hydraulic cylinder device 37 and a rail 47 capable of pressing the front end cutting surface of the steel piece 9 against the rear end cutting surface of the piece 8.

Next, the operation of the continuous hot rolling apparatus will be described.

In FIG. 3, the carriage 20 is made to follow the material speed so that the trailing end of the preceding strip 8 and the leading end of the succeeding strip 9 which are hot steel billets are set at the cutting position, and the strip suppressing devices 21, 22 are set.
Clamp with and simultaneously lower tool rests 23 and 24 and upper tool rest 2
The cutting device constituted by 5,26 cuts the trailing end portion of the preceding strip and the leading end portion of the succeeding strip at the same time or within a short time difference. At this time, under the upper blades 25, 26 sandwiching the strips 8, 9, the upper blade 2 is held while holding the strips 8, 9 with a certain vertical force when cutting.
A pedestal 27 that descends as 5, 26 descends is provided.

The cut crops 28, 29 indicated by the chain double-dashed line are moved in the horizontal direction at right angles to the rolling strip advancing direction by the crop extruding device 30 shown in FIG. 4, which is composed of, for example, a motor 31, a rack 32, and a pinion 33. Extruded.

After the trailing end of the preceding strip 8 and the leading end of the succeeding strip 9 are cut, the clips 28 and 29 are extruded, the holding clamp 22 of the preceding strip 9 is opened, and the trailing end position is the position of the high frequency heating device 63. So that the speed of the traveling carriage 20 is controlled, the restraining clamp 21 of the trailing strip 9 is opened, and the strip 9 is pressed by the pressing device 35 to the tip of the preceding strip 8 at the same high-frequency heating device 63 position. Set it so that it slightly touches the rear end of the strip 9 or keeps a certain distance. After setting, the temperature is raised by the high-frequency heating device 63, and the temperature of the rear end of the strip 8 and the temperature of the tip of the strip 9 are adjusted.
When the temperature reaches 1250 ° C to 1450 ° C, the strip 8 is suppressed and clamped by the clamp 65, and then the pressure device 35 press-joins. The pressing force is preferably 3 kg / mm ² or less.

Thereafter, the joined steel pieces are guided to the finishing rolling mill group 4 and continuously rolled, as shown in FIG.

FIG. 7 is a schematic view of a high frequency heating device.

This embodiment includes all those having the following functions.
That is, (1) detectors 61, 62 for detecting the positions of the trailing end of the preceding strip and the leading end of the succeeding strip (2) The strip clamp device 21, which fixes both ends before cutting and joining them. 22 (3) Cutting device for cutting both ends in clamped condition 23, 24,
25,26 (4) Crop processing device for processing the cutting crop after cutting 30 (5) Pressing device for pressing the vertical cross section of the leading end of the succeeding strip against the vertical cutting surface of the trailing end of the preceding strip
35 (6) High-frequency heating device that heats both cross-sections (7) Movable device that performs cutting, joining, and the operations accompanying them while following the progress of the strip 20 The strip thus joined is cut in front of the winder. There is a need to. In this case, as shown in FIG. 2, if the flying shear 14 is provided on the exit side of the pinch roller 6, a constant tension is always applied to the finish stand outlet, and the plate width variation due to the bending of the plate and the change in tension is small. Become. The operating looper 5 between the finishing stands shown in FIG. 1 by continuation is replaced with the fixed tension meter 16 as shown in FIG. 2, so that the facility cost can be reduced and the maintainability can be improved.

〔The invention's effect〕

According to the present invention, it becomes possible to weld the trailing end portion of the preceding hot steel piece and the leading end portion of the following hot steel piece in a short time and economically, and to continuously weld these hot steel pieces. The effect that the continuous hot rolling equipment of the hot billet which carries out the hot rolling can be realized is achieved.

[Brief description of drawings]

FIG. 1 is a schematic view showing the arrangement of a conventional hot strip mill, FIG. 2 is a schematic view showing the arrangement of a hot strip mill capable of continuous rolling to which the present invention is applied, and FIG. Overall view of a continuous strip joining apparatus according to an embodiment of the invention, No. 4
FIG. 5 is a plan view of FIG. 3, FIG. 5 is a VV arrow view of FIG. 4,
Figure 6 shows good heating temperature (° C) and pressing force (kg / mm ² )
FIG. 7 is a schematic view of a high frequency heating device. 35 …… Pressing device, 63 …… High frequency heating device.

Claims (4)

[Claims] 1. A clamp in which a trailing end portion of a hot-working steel strip that travels in advance after rolling by a rough rolling mill and a leading-end portion of a hot-working steel strip that travels behind are clamped in close proximity to each other. And the rear end portion of the hot-working steel piece that travels in advance, and each of the front-end portions of the hot-working steel piece that travels backward, with a blade along the plate thickness direction of the hot-working steel piece. A step of advancing and cutting, the rear end of the hot steel slab that travels in advance, and the cutting end of each of the front end of the hot steel slab that travels afterwards by high-frequency heating at 1250 ° C. A step of heating up to a temperature range of 1450 ° C., and cutting of the leading end of the trailing hot steel billet with respect to the cutting surface of the trailing end of the preceding hot billet running A step of pressing and joining the surfaces, a step of hot rolling the joined hot steel slab with a finish rolling mill, and winding the hot rolled hot steel slab with a winder A continuous hot-rolling method for hot-rolled billets, comprising: 2. The continuous hot rolling method for hot-rolled steel billet according to claim 1, wherein the trailing end of the preceding hot-rolled steel billet and the leading end of the trailing hot-rolled steel billet. In the section, the cutting step, the heating and heating step, and the pressing and joining step, respectively, run the hot steel billet so as to substantially match the traveling direction speed of the hot steel billet. The method for continuous hot rolling of hot steel slabs, characterized in that 3. A rolling mill provided between the rough rolling mill and the finish rolling mill,
In a continuous hot rolling apparatus for a hot steel billet, which comprises a joining device movable along the traveling direction of the hot steel billet, the joining device is extended along the traveling direction of the hot steel billet. The joining device is provided on a carriage that is movably mounted on a rail, and the joining device includes a trailing end portion of a hot steel strip that travels in advance and a leading end portion of a hot steel strip that travels behind. A clamping device for clamping, a rear end portion of the hot-working steel piece that travels in advance and a tip end portion of the hot-working steel piece that travels backward are provided with vertical blades, and the blades are hydraulic cylinders. A cutting device for advancing along the plate thickness direction of the hot steel billet by a device, and a rear end portion of the hot steel billet traveling in advance and a tip end portion of the hot steel billet traveling backward. A high-frequency heater that heats and raises each of the cut portions, and one of the hot steel slabs that travels forward and backward. And a pressing device for sandwiching and transporting the steel slab and pressing the cut surface of the hot steel slab against the cut surface of the other hot steel slab. A continuous hot-rolling apparatus for hot-rolled billets, characterized in that a winder for winding the hot-rolled hot-rolled billets is arranged downstream of a finish rolling mill for hot-rolling hot-rolled billets. 4. A continuous hot rolling apparatus for hot-rolled steel billets according to claim 3, wherein the carriage is provided with each cutting portion of the hot-rolled steel billet cut by the cutting device. A continuous hot rolling apparatus for hot-rolled steel billets, characterized by comprising a transfer device for removing the hot-rolled billets outside the running path.