JPH0452021A - Method for controlling cooling of flange of h shape - Google Patents

Abstract

PURPOSE:To allow the manufacture of H shape whose ratio of the flange to the wed is large, i.e., H shape of excellent sectional performance by utilizing the trucking information of steel material, operating the cooling zone sequentially and successively jetting the cooling liquid. CONSTITUTION:When the material to be rolled is rolled to (13) direction, the surface temperature of the material to be rolled is measured with both flange thermometers 7a, 7b before the flange cooling device having two zones 9, 10 of the inlet sides of the universal mill U and the edger mill E and the wed thermometer 8, based on the difference of the temperature of the wed and the flange of the material to be rolled, whether there is or not the forcible cooling for the zones from 9 to 12 of flange cooling devices including two zones 11, 12 after U and E rolling is decided with the calculation with the calculator or with reading the table preliminarily inputted. By storing the position of the material to be rolled decided whether there is or not the forcible cooling for the zone based on the temperature difference in the calculator, the position of the material to be rolled is passed through the zone based on the trucking information of the material to be rolled, the cooling liquid is controlled to jet or not according to the instruction.

Description

[Detailed Description of the Invention] [Industrial Field of Application] Because H-beam steel has excellent cross-sectional properties, it is not used as building materials or mechanical structural materials, and in order to further improve its cross-sectional properties, it is often used with flanges. There is a demand for increasing the thickness ratio of the web.

The present invention relates to improvements in a computer-based flange cooling control method for reducing residual stress generated during the manufacturing process of such H-section steel having a large flange-to-web thickness ratio.

[Prior art] H-shaped steel has a unique cross-sectional shape compared to steel plates and steel pipes, so during the manufacturing process by hot rolling, residual stress is generated mainly due to the temperature difference between the flange and the web. arise. Normally, the flange portion is thicker than the web portion and is difficult to cool, so the flange portion is pulled and compressive residual stress is generated in the web portion. In extreme cases, the influence of residual stress exceeds the permissible compressive stress of the web and appears as a web waviness phenomenon. For this reason, as a means to minimize the temperature difference between the flange portion and the web portion, a forced cooling device for the flange is generally installed adjacent to the rolling mill.

In addition, H-beam steel usually has a flange width of 100 mm to 40 mm.
Since the web height ranges from 100+nm to 900mm, cooling is done in consideration of the size of the steel material. Figure 2 is a cross-sectional view of the material being passed through the H-section steel. As shown in FIG. 2, the flange cooling device is composed of a nozzle group 3 for cooling the rolled material and a guide device 4 that is movable according to the web height of the H-section steel. As shown in FIG. 2, the H-shaped steel being conveyed on the table 6 is forcedly cooled from the lateral direction by the nozzle group 3 arranged in the height direction and in the direction of the appropriate material in the rolling position.
It is numerical. In order to prevent water from riding on the web 5a, the seventh
Nozzle selection in the height direction according to the flange width is performed by 0N10FF of the valve 37 shown in FIGS.

In addition, in Japanese Patent Publication No. 57-59003, the temperature of the flange and web of the rolled material before rolling is measured, the temperature at a predetermined position after rolling is estimated from the measured values, and the estimated temperature is A method is disclosed in which the relative difference between the estimated temperature difference and the allowable temperature difference is determined, and the cooling capacity of a forced cooling device provided at a predetermined position is adjusted based on this relative difference. Generally speaking, cooling capacity is generally considered to be the flow rate per unit area, that is, the flow rate density.The control of the flow rate, which is the product of the flow rate density, flange width, and flange cooling device length, is shown in Figure 7 (b). ) The cooling capacity is adjusted by adjusting the flow rate of the cooling liquid through feedback control of the flow rate adjustment valve 33 and the flow meter 32.

[Problems to be Solved by the Invention] However, adjusting only the cooling capacity is not suitable for H-section steel with a large heat capacity ratio between the flange and the web, a small allowable temperature difference between the flange and the web, and a large thickness ratio between the flange and the web. It is difficult to perform H-shape rolling of many sizes including the above-mentioned size due to the reasons described below.

■In terms of equipment, adjusting the cooling capacity after adjusting the flow rate corresponding to the flange width direction has a control limit due to the relationship between the valve and water pressure turndown ratio. ■The method of adjusting the rolling speed to provide the necessary forced cooling has problems such as a reduction in rolling efficiency due to the low rolling speed and the need for a large control margin in the cooling capacity adjustment device to cover thermal run-down. ■If the cooling capacity is too large, the surface hardness of the H-section steel will become too high, which may cause problems in workability.

The present invention provides a method for solving the problems of flange cooling control that involves simply adjusting the cooling capacity.

[! ! Means for Solving the Problems] That is, the gist of the present invention is as follows.

1. A forced cooling device for the flange part of H-beam steel that is long enough for the length of the steel material divided into multiple cooling control zones during the intermediate and finishing processes of H-beam steel that undergoes hot rolling processing. On the other hand, a flange cooling control method for an H-shaped steel is characterized by sequentially operating cooling control zones and injecting a cooling liquid based on tracking information of the steel material.

2. For each cooling control zone described in l above, during steel rolling, in a piping system that has a switchable gate or valve, the cooling device is used when steel is being cooled, and the drainage equipment is when steel is not being cooled. , the coolant flow rate is maintained at a preset flow rate for each size, and gates or valves corresponding to the plurality of cooling control zones are controlled based on calculation of the material passing speed and temperature information during tracking, or based on preset conditions. A method for controlling flange cooling of an H-section steel, characterized by switching and injecting a cooling liquid.

The present invention will be explained in detail below.

Focusing on the cooling method that is commonly used between the finish rolling mill and the winding device for sheet materials, we focused on the cooling method that is commonly used between the finish rolling mill and the winding device for plate materials, and focused on the cooling method that is meaningful for 3 m.
By arranging a plurality of cooling devices having a cooling length of ~61 in the over-material line direction and turning each cooling device ON10FF, the turndown ratio can be increased to a ratio proportional to the number of cooling devices. Further, since there is no need to adjust the rolling speed extremely low, there is no reduction in rolling efficiency, and there is no need to consider equipment for thermal rundown. Since cooling is possible with a roughly appropriate cooling capacity, there are no problems with workability. A new problem that arises with this method is how to suppress flow rate fluctuations when turning ON10FF. In other words, when the valve 38 is suddenly opened in FIG. 7(b), the flow rate flowing into the cooling device becomes 1.2 to 1.4 times that in the steady state, increasing the amount of cooling liquid applied to the steel material and reducing the continuity of the cooling capacity. Measures must be taken to avoid collapse.

For this purpose, in FIG. 7(a), the flange water cooling device 36
By arranging a switchable gate or valve 34 on either the drain device 35 or the drain device 35, and switching the flow direction of the cooling liquid based on a command from a computer, it is possible to maintain continuity of cooling performance.

[Function] Figure 1 shows a general layout for manufacturing H-section steel by hot rolling. The rolled material heated by the heating furnace 1 is roughly rolled by a break down mill BD, then intermediately finished by a rough ink mill Or consisting of a universal mill U and an Escher mill E, and further finished by a finishing mill Of. It is then rolled out.

The rolled material finished into a predetermined cross-sectional shape is cut into double sizes by the first hot saw 115, and then cut into regular sizes by the second hot saw 2H5. fi
Afterwards, the rolled steel material is taken into the cooling bed 2 and cooled, and then straightened by a roller strainer R5 to become a product. Forced water cooling of the flange of H-beam steel is effective when it is rolled in mills Or and Of after intermediate finishing, so that the shape is close to a predetermined cross-sectional shape.

FIG. 3 shows an embodiment in which flange cooling devices are arranged on the front and rear surfaces of Or. When rolling the material to be rolled in the direction 13, the two flange thermometers 7a, 7b and the web thermometer 8 are placed in front of the flange cooling device having two zones 9 and 10 on the inlet side of the universal mill U and edger mill E. The surface temperature of the material to be rolled is measured, and depending on the temperature difference between the flange and web of the material to be rolled, whether or not forced cooling is performed in zones 9 to 12 of the flange cooling device, including the two zones 11 and 12 after U and E rolling. is determined by calculation by a computer or by reading a table given to the computer in advance.

The position of the rolled material whose zone is forcedly cooled or not is determined based on the temperature difference is stored in the computer, and when the location of the rolled material passes through the zone based on the tracking information of the rolled material, the computer Controls with or without coolant injection according to the command. Further, when rolling the material to be rolled in the direction 14 opposite to the above, thermometers 7a' and 7b' are used to measure the surface temperature of the material to be rolled.
The effect is the same except that . In the embodiment, there are two flange cooling device zones on the front and rear surfaces of the rolling mills U and E, but the number is not limited to two, nor is it limited to the same number on the front and rear surfaces. All systems in which a computer commands whether or not forced cooling is performed over multiple zones are included in the present invention.

Furthermore, FIG. 4 shows a flange cooling device adjacent to finishing mill Uf, which is the final step of hot rolling. It is assumed that the material to be rolled is rolled in the direction 23.

The surface temperature of the material to be rolled is measured using both flange thermometers 15a and +5b and the web thermometer 16, and based on the temperature difference between the flange and web of the material to be rolled, zones 17 to 22 of the flange cooling device are forcedly cooled as described above. The presence or absence is determined by calculation by a computer or by reading a table previously given to the computer. The finishing mill Of is not limited to between the thermometer and the flange cooling device, and depending on the layout, it may be installed upstream of the thermometer or downstream of the flange cooling device. The basic formula for computer calculations is from 1932.
Based on the knowledge that forced cooling time is effective in reducing residual stress, as shown in Figure 5 (a) and (b), which is data announced at the Japan Iron and Steel Institute in November 2016, the size with a constant cooling capacity was The simplest method is to set the forced cooling time to each time.

As mentioned above, the cooling capacity is determined by the flow density ejected from the flange cooling device. The flow rate of the coolant is the product of the flow density set for each size, the flange width, and the zone length. FIG. 7(a) shows the piping flow of the coolant flowing from the right side to the left side. As shown in Fig. 8, the flow rate adjustment valve 33
sets the opening according to the flow rate set by the computer, and performs feedback control based on the indicated value of the flow meter 32.

One outlet of the three-way valve 34 on the downstream side of the flow control valve 33 is piped to a flange cooling device, and the other to a drainage device 35, and switching is performed based on tracking information. Figure 6 shows a case where the pump equipment 24 is installed on the entry side, and the piping flow shown in Figure 7 (a) is arranged in multiple zones.If the rolled material is overloaded from right to left, the tracking information Accordingly, the three-way valves corresponding to zones 25 to 30 are sequentially switched to the flange cooling device side based on the zone selection command.

FIG. 9 shows an example of a three-way valve switching logic for zone selection. Call up the required flow rate density for each size and the web and flange temperature difference target after forced water cooling for each size that have been registered in advance in the calculator, and have the computer calculate the forced cooling time from the actual temperature values of the web and flange during actual rolling. . Furthermore, the number of zones required for cooling is determined by dividing the forced cooling time by the rolling speed. This trick allows you to specify the cooling zone and switch the three-way valve. The data to be registered in the computer is, for example, H900x 3 in Figures 5 (a) and (b).
As in the data of 00x16x28, cooling capacity Hf = 2
50 Kcal/m2h"c, air cooling, 1 minute cooling, 2
Data on temperature conditions such as minute cooling and residual stress are obtained through experiments, and the cooling time and temperature difference between the web and flange corresponding to the allowable residual stress value are registered as data. It is also possible to calculate the relationship between temperature difference and residual stress through simulation and register the results as data. During size rolling, which does not require calculation by a computer, it is also possible to specify a cooling scene in advance.

[Effects of the Invention] By employing the above-described flange cooling control method of the present invention, it becomes possible to manufacture an H-section steel with a large flange-to-web thickness ratio, that is, an H-section steel with excellent cross-sectional performance. The number of zones in the flange cooling system and the number of zones multiplied by the captain are:
It is determined by the range of equipment cooling capacity and rolling speed that satisfies the cooling performance required for the size to be rolled.

As mentioned in the problem to be solved by the invention, if the cooling capacity is too large, the required quality of the product, for example, the surface hardness will become too high, and the controllability will be affected because the rolled material is cooled in a short time. The difficulty increases. Furthermore, if the rolling speed is too low, the production efficiency will decrease as described above. The number of zones and machine length of the flange cooling device have optimum values depending on the size range to be manufactured, and can be determined economically by taking the above points into consideration.

[Brief explanation of the drawing]

Figure 1 is a schematic diagram showing the H-section steel manufacturing process, Figure 2 (a)
(b) is a front view and its A-A arrow view showing an example of a cooling device for an H-section steel flange, FIG. The figure is an explanatory diagram showing the flange cooling device adjacent to the finishing mill Of, Figures 5 (a) and (b) are graphs showing known data, and Figures 6 and 7 (a) and (b) are cooling fluids. Various piping flow diagrams, FIGS. 8 and 9 are block diagrams showing control flows.

Claims (1)

[Claims] 1. A flange portion of an H-beam steel having a length sufficient for the length of the steel material divided into a plurality of cooling control zones during the intermediate and finishing processes of the H-beam steel subjected to hot rolling processing. A flange cooling control method for an H-shaped steel, which comprises sequentially operating cooling control zones and injecting a cooling liquid to a forced cooling device for a steel material, based on steel material tracking information. 2. For each cooling control zone according to claim 1, in a piping system having a switchable gate or valve, for the cooling device when steel is being cooled, and for the drainage equipment when steel is not being cooled, the steel rolling During the process, the coolant flow rate is maintained at a preset flow rate for each size, and gates or valves corresponding to the plurality of cooling control zones are controlled based on the calculation of the material passing speed and temperature information during tracking, or preset conditions. A method for controlling flange cooling of an H-section steel, characterized by switching the flange and injecting a cooling liquid.