JPH0543926Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an improvement in a forced cooling device for hot steel plates, particularly hot rolled thick steel plates.

[Conventional technology] In recent years, in the field of manufacturing thick steel plates, against the background of advances in various technologies such as controlled rolling and process computers for the entire rolling line, it is now possible to obtain the desired material by performing controlled cooling immediately after hot rolling. Technological development regarding so-called online accelerated control cooling is currently underway, and many research publications and patent applications have already been filed.

The two important points in the controlled cooling are to make the material of the steel plate uniform within the plate and to maintain a good shape of the plate after cooling. As a means of dealing with these problems, for example, a method as shown in JP-A-57-41317 is a technique for preventing the occurrence of waves and warping of steel sheets in the normal temperature range due to uneven temperature distribution in the sheet width direction. With the subsequent progress in research and development, a cooling method has been proposed that further enhances the effect of preventing shape defects in steel sheets, as shown in Japanese Patent Application No. 255050/1983.

On the other hand, as a conventional technique for preventing the occurrence of shape defects such as warpage and distortion at the leading and trailing ends of a steel plate in the room temperature range due to uneven temperature distribution in the longitudinal direction of the steel plate, for example, Japanese Patent Publication No. 63-1376 is known. As shown in FIG. A method is known in which the amount of cooling water passing through a position where the leading end and/or trailing end of a heated steel plate passes through is controlled, thereby achieving a uniform temperature distribution over the entire length of the steel plate after cooling.

These conventional techniques include, for example, the apparatus shown in FIGS. 4 and 5, in which a hot steel plate 1 is connected to nozzles connected to nozzle headers 8 and 9 provided between adjacent conveying rolls 2 and between restraining rolls 3. 4 and 5, the amount of cooling water passing through the front and rear ends of the plates is controlled by shielding plates 60 provided above and below the nozzles.

On the other hand, the technology disclosed in Japanese Patent Publication No. 63-1376 focuses on the differences in the behavior of water on a steel plate at the tip, rear end, and center of the plate, and calculates the collision pressure of spray water on the steel plate surface. By changing the temperature distribution at the tip, rear end, and center, a uniform temperature distribution can be obtained over the longitudinal direction of the steel plate. However, in conventional technology, it is possible to obtain a uniform temperature distribution by eliminating the disturbance caused by falling water. Achieving cooling requires a huge number of trials and errors, and even if an optimal control pattern is obtained, the influence of disturbances caused by falling water is large, making theoretical predictive calculations extremely difficult.

[Problem to be solved by the invention] In the conventional cooling device shown in FIGS. 4 and 5, a shield plate 60 is installed as a masking device for cooling water at the front end and rear end of the hot steel plate. ,
The shielding plate is configured to be able to reciprocate by a shielding plate driving cylinder 63, and the shielding plate driving cylinder is actuated by a shielding plate on-off timing control mechanism (not shown). The signal changes the spray holes 65 of the apron 61 and the spray holes 64 of the shielding plate from the open state shown in FIG. 5a to FIG. 5b.
It is configured to be moved to the closed state shown in the figure, or from the closed state to the open state. Therefore, the cooling water that was cut off when masking the tip of the steel plate stagnates on the shielding plate, and after the masking is released, the masked part (uncooled length) Lf of the tip of the steel plate shown in Figure 3 ( fall into the water on the rear side of n). As a result, a temperature distribution (hatched area) in which the rear part of the masking part Lf(n) at the tip of the steel plate is supercooled occurs in the longitudinal direction of the steel plate as shown in Figure 6, and the tip of the steel plate is warped after cooling. , causing distortion, etc.

In addition, as a cooling water cutoff means, in the case where a cutoff valve (not shown) for cutting off the cooling water is provided in the nozzle headers 8 and 9, as is known in Japanese Patent Application Laid-open No. 61-015926, instead of the above-mentioned shielding plate. , the above-mentioned problem of falling water is eliminated, but when masking the leading and trailing ends of the steel plate, the cooling water that is cut off may leak behind and behind the masking part Lf(n) at the leading edge of the steel plate. The cooling water flowing to the nozzle header located in front of the masking part Lt(n) increases (Max. 200%) and the temperature distribution in the longitudinal direction of the steel plate after cooling as shown in Fig. 6. , supercooling occurs behind the masking portion Lf(n) at the tip of the steel plate and in front of the masking portion Lt(n) at the rear end as shown by the hatched area in FIG. If a method of providing independent flow control devices 40, 41 for each nozzle header 8, 9 is adopted as a solution to this problem, the amount of equipment investment will increase significantly.

An object of the present invention is to provide a cooling device that can solve the problems of the prior art and make the temperature distribution of a hot steel sheet uniform in the longitudinal direction.

[Means for Solving the Problems] A cooling device of the present invention for achieving the above object is configured as follows. That is, hot steel plate 1
Water injection pipes 20 to 2 are connected to nozzle headers 8 to 11 each having a plurality of spray nozzles 4 to 7 above and below.
Connect to 3. And this water injection pipe 20-2
A high-speed switching three-way valve 12 to 15 is disposed in each of the three. Two of the three sides of the three-way valves 12 to 15 serve as a water supply inlet and a water supply outlet to the nozzle headers 8 to 1.
1 so that water can be supplied, and the other is connected to nozzle header 8~
When water is not supplied to the 11 side, it is connected to the drainage pipes 24 to 27 as a relief. Orifices 16 to 19 having the same pressure loss as the nozzle headers 8 to 11 are arranged in the drainage pipes 24 to 27 at positions within 12 times the diameter of the drainage pipes 24 to 27.

[Function] A high-speed 3-way switching valve is used as a shielding valve for the nozzle header, and an orifice is installed to balance the pressure loss from the high-speed 3-way switching valve to the nozzle outlet provided in the nozzle header with the pressure loss in the relief piping. By providing within 12D from the center of the high-speed 3-way switching valve, when one high-speed 3-way switching valve is activated (cooling water release state), it reduces the flow fluctuation of another nozzle header connected through piping, Since the on/off control of the cooling water at the leading end and/or rear end of the hot steel sheet is performed stably according to the size of the hot steel sheet, the cooling pattern, the temperature pattern after controlled rolling, etc., the temperature of the hot steel sheet due to the flow fluctuations is Supercooling behind the masking portion Lf(n) at the tip and/or in front of the masking portion Lt(n) at the rear end can be extremely reduced. Furthermore, since disturbance factors are reduced, even when temperature prediction calculations are required, analysis becomes easier compared to conventional cooling devices.

[Examples] Examples of the present invention will be described in detail below with reference to the drawings. FIGS. 1 and 2 show an embodiment of the present invention, and FIG. 3 shows an embodiment of tracking control at the leading and trailing ends.

FIG. 1 is for explaining a cooling water control piping system which is an embodiment of the cooling device of the present invention. The hot steel plate 1 has a length L and a uniform thickness in the plate width direction, and the plate width is substantially the same over the entire length. Reference numeral 2 denotes a transport roll, and 3 a restraint roll installed above the transport roll 2, which presses the hot steel plate 1 from above. A rotation speed detector 50 for tracking and controlling the conveying speed and current position of the hot steel plate 1 is connected to the conveying roll 2 . Nozzle headers 8 and 9 are installed in an upper and lower pair between the conveying roll 2 and the restraining roll 3, and connect a plurality of spray nozzles 4 and 5 at a predetermined pitch in the width direction of the hot steel plate 1.

12 and 13 are high-speed three-way switching valves, the water supply inlets are connected to the flow control devices 40 and 41 via pipes 28 and 29 and 32 and 33, and the water supply outlets are connected to the flow control devices 40 and 41 via pipes 20 and 21, respectively. Nozzle header 8,
9, the drainage outlet sprays cooling water through nozzles 4 and 5.
The drain pipes 24 and 25 are connected to drain pipes 24 and 25 for direct drainage to a drain pit (not shown). Furthermore,
The drainage pipes 24 and 25 have an orifice 16,
17 are connected in series, and this orifice has two types of high-speed three-way switching valves, 20, 24 or 21,
The orifice diameter is set so that the pressure loss will be the same no matter which one is selected. The above is the cooling water control piping system connected to the upper and lower spray nozzle groups 4 and 5.

Similarly, 6, 7 and 10, 11 are transport rolls 2.
and another upper and lower pair of spray nozzles and nozzle headers installed between the restraining rolls 3, 14,
15 is a high-speed three-way switching valve, 30 and 31 are piping for the inlet side of the high-speed three-way switching valve, 22, 23 and 26, 27 are piping for the outlet side of the high-speed three-way switching valve, 18 and 19 are orifices, and 42 and 43 are flow rates. It is a control device. The flow control devices 40, 41 and 42, 43 are connected to a water supply header 36 that is supplied with cooling water from a water supply device (not shown).

FIG. 2 is for explaining the control of the cooling device according to the embodiment of the present invention. 45 is a cooling device;
It is composed of each device explained in FIG. 51
is a cooling calculation device that calculates the material, dimensions, and cooling conditions of the heated steel plate given by the factory management computer (not shown) and the surface temperature of the heated steel plate measured with a thermometer (not shown) installed in the conveyor line. The control conditions for each component of the cooling device are calculated from the above, and the control is implemented.

52 is a conveyance control device, which controls the sheet passing speed in the cooling device based on the sheet passing speed given from the cooling calculation control device 51, the hot steel plate length L, and the actual sheet passing speed value from the rotation speed detector 50; Implement tracking control for hot steel plate position detection. 53 is a high-speed three-way switching valve control device, which switches and controls each high-speed three-way switching valve at a preset timing based on a signal from the conveyance control device 52, and turns on and off the spray cooling water used for cooling the hot steel plate.

Next, a specific control embodiment will be described with reference to FIG. The flow rate control devices 40 to 43 are set to the upper and lower water flow rate command values calculated by the cooling calculation control device 51 based on the cooling conditions of the thickness of the heated steel plate and the shape control conditions of the steel plate.

When the hot steel plate 1 has not entered the cooling device 45 (cooling has not started), the flow rate control device 4
The cooling water set from 0 to 43 is controlled by the high-speed three-way switching valve 12.
-15, it is selected to spray from spray nozzles 4-7. In addition, high-speed three-way switching valves 12 to 15
Orifices 16 to 19 are provided so that the pressure loss in the water channel is the same regardless of whether the spray nozzle side or the drainage piping side is selected, and the flow rate of the flow rate control devices 40 to 43 can be changed depending on the selected direction. It is considered that there will be no Further, as explained in FIG. 2, the position of the tip of the hot steel plate 1 is constantly detected by the conveyance control device 52 based on the signal from the rotation speed detector 50.

When the heated steel plate 1 starts to enter the cooling device at the speed specified by the conveyance control device 52, a signal is sent from the conveyance control device 52 to the high-speed three-way switching valve control device 53 when the leading end reaches the #1 roll, and the next Then, the high-speed three-way switching valve control device 53 sends a close command (cooling water is on the drainage side) to the high-speed three-way switching valve between the #1 and #2 rolls, and the injection of cooling water from the spray nozzle is stopped. At this time, the close command is sent in advance, taking into consideration the delay time Δt _{1 from the close command to the stop of the cooling water from the spray nozzle, so that the injection of cooling water will stop when the tip of the plate reaches the #1} roll. Next, the masking length (uncooled length) of the tip part Lf (1)
When reaching this point, the high-speed three-way switching valve control device 53 issues an opening command, and the injection of cooling water from the spray nozzle is restarted. In this case as well, the open command is issued in consideration of the delay time Δt ₂ from the open command to the start of the spray nozzle cooling water injection. Similarly, when roll #2 is reached, a close command is issued and the tip of Lf(2) is masked, and when roll #n is reached, a close command is issued and the tip of Lf(n) is masked. Note that the number of times n of tip masking and the masking length Lf(n)=[n=1 to N] can be set arbitrarily. (N is the number of nozzle headers installed with high-speed three-way switching valves) Regarding the masking of the rear end, the rear end is #n
Masking length Lt of the rear end after reaching the roll
This is done by issuing a close command when the position (n) is reached, and issuing an open command when the rear end reaches roll #n+1.

In the above explanation, there is no distinction between upper and lower, but both have the same control function independently.
By arbitrarily setting the combinations of the top and bottom, the number of masking n, and the masking length [Lf (n), Lt (n)] so that the longitudinal temperature distribution and shape of the steel plate after cooling are optimal. controlled.

Figure 10 shows the actual measured value of the time required for the nozzle header pressure to stabilize at the set value after the nozzle header water injection starts after the above-mentioned open command in this example, but within 0.3 seconds when the flow rate is 2 m/sec or more. is stable. When accelerated cooling of a hot steel plate is performed using the hot steel plate cooling device of this embodiment, the controllability is extremely effective compared to the conventional method.

[Effects of the invention] The effects of the invention are listed below.

(1) In conventional cooling systems, the tip of the heated steel plate and It was extremely difficult to uniformly cool the temperature distribution at the rear end, but with the present invention, the problems of the previous stage have been resolved and uniform cooling can be achieved over the entire length of the steel plate.

(2) Due to the previous step (1), the entire length of the steel plate becomes a uniform material.

(3) Due to the former step (1), shape defects of the steel plate are significantly reduced.

(4) Disturbances caused by flow fluctuations during control can be eliminated and temperature controllability can be improved.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram of cooling control piping of a cooling device according to an embodiment of the present invention. FIG. 2 is a configuration diagram of a control device according to an embodiment of the present invention. FIG. 3 is a diagram showing the relationship between the masking lengths of the leading and trailing ends of the steel plate and the control timing of the high-speed three-way switching valve according to the embodiment of the present invention. FIG. 4 and FIG. 5 are explanatory diagrams of a conventional cooling device. Figure 6 shows the temperature distribution in the longitudinal direction of the steel plate after cooling in a conventional cooling device. Figure 7 is a schematic diagram of the experimental equipment. Figure 8 shows the experimental results of steady state pressure fluctuations in a series of water supply headers when a high-speed three-way switching valve is in operation and one valve is in the relief state. Figure 9 shows the experimental results regarding the time it takes for the orifice effect of the relief piping to appear after the high-speed three-way switching valve operates. FIG. 10 shows experimental results regarding the time required for the nozzle header pressure to stabilize after the high-speed three-way switching valve is operated. 1... Hot steel plate, 2... Conveyance roll, 3... Restraint roll, 4, 5, 6, 7... Spray nozzle, 8, 9, 10, 11... Nozzle header, 1
2, 13, 14, 15...high-speed three-way switching valve, 1
6, 17, 18, 19... Orifice, 20, 2
1, 22, 23...Water injection piping, 24, 25, 2
6, 27...Drainage piping, 28, 29, 30, 3
1... Connection piping for inlet side, 32, 33, 34, 35
...Inlet pipe, 36...Cooling water supply main pipe, 40,
41, 42, 43...Flow control device, 50...Rotation detector, 51...Cooling calculation control device, 52...
Conveyance control device, 53... High speed three-way switching valve control device, 60... Shielding plate, 61... Apron, 63...
...Cylinder for driving the shielding plate.

Claims (1)

[Claim for Utility Model Registration] A plurality of presser rolls are arranged at symmetrical positions above the rolls of a roller table on a conveyance line for hot steel plates, and a cooling liquid is injected onto the hot steel plate being conveyed above and below between the presser rolls. In a cooling device for a hot steel plate in which a nozzle header equipped with a plurality of spray nozzles is arranged, water injection piping 20 is installed in each of the nozzle headers 8 to 11.
- 23 are connected, high-speed three-way switching valves 12-15 are arranged in each of the water injection pipes 20-23, and each of the high-speed three-way switching valves 12-15 is connected to an inlet connecting pipe 2.
8 to 31 are connected, and the connection pipes 28 to 31 for the inlet side are connected.
A plurality of the above-mentioned high-speed three-way switching valves 12-15 are assembled together and connected to the inlet pipes 32-35, and a flow rate control device 40-43 is provided in each of the inlet-side pipes 32-35. For those, nozzle header 8-1
1, the connection pipes 28 to 31 for the inlet side are arranged on the water supply upstream side, and the water injection pipe 2
0 to 23 are connected to the downstream side of the water supply, and the other is connected to the drainage pipes 24 to 27 for relief.
The drain pipes 24 to 27 are connected to the drain pipes 24 to 27, and are provided with orifices 16 to 19 having a pressure loss equivalent to the pressure loss of the nozzle headers 8 to 11 at positions within 12 times the distance of the drain pipes 24 to 27. Cooling equipment for hot steel plates.