JPS5947009A - Manufacture of h-beam with thin web thickness - Google Patents

Abstract

PURPOSE:To restrict the generation of the wave of a web, by maintaining the flanges and the web of a hot rolled H-beam with thin web thickness at the specific temperatures respectively, and clamping the web by directly contacting type press plates to cool forcibly the outside surfaces of the flanges. CONSTITUTION:An H-beam 29 with thin web thickness consisting of a web 30 and flanges 31a, 31b is conveyed from a finish mill to a forced cooling yard. Here, the web part 30 is tightly clamped by contacting-projections 33a, 33b and 33c, 33d of directly-contacting type press plates 32a and 32b. Further, the temperatures of the flange and the web are maintained at the temperatures ranging Ar1 transformation point - 250 deg.C, and 550-100 deg.C respectively. Next, a cooling water is sprayed onto the outsides of the flanges 31a, 31b from the groups of nozzles 35a, 35b through water feeding pipes 37a, 37b to cool them. Thus, the web 30 is prevented from the generation of wave, and the wave is slight even if it generates.

Description

[Detailed description of the invention]

The purpose is to create a web with an excellent shape without web waves.
Method for manufacturing H-beam steel J) A. The well-known thin-walled H-beam steel, which has a large continuous section modulus and superior Ui' properties compared to steel, has problems with web waves when manufactured by rolling, and there are examples of it being supplied to the tFj field. do not have. In addition, build-up H-beam steel produced by welding still has drawbacks such as welding distortion and high cost. According to the rolling manufacturing method, the occurrence of web waves is generally caused by the generation of compressive internal stress in the web that exceeds the buckling limit of the web due to residual stress caused by the temperature difference during the cooling process between the flange and the web. For this reason, a cold IJ step has been proposed that equalizes the temperature of the flange and web. However, in the case of web H-beam steel, the 7-run is relatively thick and has a wide web, and the web height is high, so the difference between the flange and the web is +1. It is very difficult to reduce the difference in A degree, and the residual stress between -C is too large υ,
On the other hand, it is extremely difficult to suppress web waves because the web seat M (limit) is low.It will be further explained below with reference to the drawings. FIG.
! In the rolled H-section steel 18 with 7 flange 2a t Zb, the web thickness Wt is thinner than the flange thickness Ft.
4 days''; as shown in 41(b), heat %: f, l: ”
]'f+j(However, as described above, web wave 3 is generated in web I and it is difficult to form a product. Therefore, in the present invention, web H type H type is defined as web μ%
The ratio Wt/u of Wj and +1J II in the web is 0.017
Refers to all of the following, its τ" method bl'5t", reason (
If the ratio t/u is 0.017 or more, it is difficult for web waves to form, and the ratio is 0.017 or more. (This is because we know from experience that web waves are generated when the temperature is J17 or lower. The generation of web waves is due to web buckling, and the web buckling stress is T, the square of the above ratio wt/u! IIchi(”'t/,
) is roughly proportional to 2, and this (t/u) is 3×10
When the temperature is below, web ino ν occurs in the normal hot pressing-air cooling process). Next, the generation of residual stress in rolled H-section steel will be explained in terms of >v'. In Figure 2 (a), the horizontal axis is Sukema, and the vertical axis is

[21
4 is the flange humidity, 5 is the web temperature, 6I:j is the Franz temperature after the start of water cooling, and 7 is the +7. i)SH difference,)N
The tt and A degree difference after starting IJ Franz water cooling are shown. At the initial time A after the end of hot rolling, a 1"-compression stress is generated in the Franz and a tensile stress is generated in the web.
). This figure is a Ume-2 figure that explains the residual stress for the side view of the I4 type (1.11) in air cooling, and the neutral 111
11+9 v, with compressive stress on the right and tensile stress on the left centered. Therefore, at time A, tensile stress is applied to the web (not shown in the firearm 10), and compressive stress is applied to Franz, shown by the solid line 11.As time passes and at time B, the temperature difference between the web and the flange increases, so the web tension The stress 12 exceeds the yield point 13, the compressive stress 14 of the flange exceeds the yield point 15, and plastic strain occurs.16 is the neutral axis.Next, at time C when the temperature difference begins to decrease, due to the plastic strain When the stress-free state is reached and cooling proceeds for a further time, a tensile stress of 17 is generated in the Franz and a compressive stress of 18 is generated in the web due to the plastic strain. Until point E is reached, a large compressive stress 19 remains in the web and a large tensile stress 20 remains in the flange Q. 21
indicates the entire neutral axis. No. 21'2.1 (c) shows the stress change during Franz water cooling after Franz transformation,
If Fujino water cooling is started at a certain time, the temperature difference between the flange and the web will be negative (that is, the web temperature will be lower than the flange temperature).
) is higher than the temperature), for example gold 7J'',
Shi, by the time F is reached when Fufunno Togurei ends,
The compressive stress 22 in the web exceeds the yield point 2:3 and causes compressive plastic deformation in the web. 25, 28e, j, neutral axes are shown. However, does it take Franz water? The Ministry is capable of sterilizing the absolute A1 change of residual awakening stress. In other words, 9. Compared to the web compressive stress of 19 and flange tensile stress of 20,
The web compressive stress 2G and the flange tensile stress 27 of Franz Water June can all be made very small δ as in this example. fjil record 5 record 5 As is clear, there is a means to reduce the generation of residual stress by reducing the temperature difference between the feed 7 and the web before reaching time B where the absolute value of stress is small. At the stage where compressive stress is accumulated in the web, it is effective to rapidly bring the temperatures of the flange and the web closer to each other or reverse them to cause compressive plastic deformation in the web and change the stress distribution. It turns out that. Possible means for this purpose include (1) forced flange cooling, (2) web heating, and (3) web insulation. Therefore, the present inventors tried to insulate the web by using a heat reflecting plate for the thin-walled (thin-web) section steel. We were not successful in suppressing the generation of waves. I also tried forced water cooling on the flange, but the same result occurred. Therefore, in addition to forced water cooling of the flange, the web was clamped and mechanically restrained by suppression plates to suppress deformation and prevent the generation of web waves, that is, the entire method of the present invention was developed. The method of the present invention uses a hot-rolled web thin-walled H-shaped @gold, a flange humidity of below the Arl transformation point to 250°C or higher, and a web temperature of 550°C to 100°C, using a web full direct contact press plate. This is a method for manufacturing a thin-walled H-beam steel web in which the entire web is mechanically restrained and the web is forcibly cooled with water to suppress the generation of web waves. The present invention will be explained in more detail in the following. Figure 3 is a schematic diagram of an embodiment of an apparatus for carrying out the method of the present invention, and 29 is a web 3 (J, Franz 31a, 31
32a and 32b are contact protrusions 33a.
r 33b + 33c + 33dffiVni This is a direct contact type pressing plate (hereinafter simply referred to as a pressing plate) which is pressed against the top and bottom of the web 30 by a suppressing device (not shown). 34a, 34b (II. Cooling nozzle box equipped with nozzle groups 35a, 35b, water supply pipes 37a, 34b via control valves 36a, 36bi
37b, and sprays cooling water on the outside of the seven lunges 31a, 31b. The H-shaped steel is transported from the finishing mill to the rolling mill by a roll gang (not shown), and is passed through the nozzle group 35a.
, 35b. At this time, the pressing plate 3
2a and 32b, the wolfberry 1300 portion is held between the contact protrusions 33a to 33d by '3+, b (because it is held between the web waves 3, 1 does not occur in the web wave 3, or even if it does occur, it is extremely small.Next, the flange A suitable procedure for cooling is shown below.The temperature of the web-thickened H-beam steel after exiting the hot finishing rolling mill is gradually lowered by cooling, but the temperature of the flange of the H-beam steel is lower than Arl.
Below transformation point to above 250℃, web temperature 550-10
Web restraint and cooling on the outside of the flange are all carried out in the temperature range of 0°C, but the temperature condition TI-'r2 between the cooling start temperature 1゛l and the cooling end temperature T2 on the outside of the flange is as follows (1
) Good results can be obtained by cooling to satisfy the formula. Here, AW; Cross-sectional area of the web AF: Cross-sectional area of the flange I σy; Yield point of the web (at the end of water cooling) σr; Residual stress of the web in normal groove σt; Web in the air-cooled state j, +Jj is Z! Stress due to the temperature difference ΔT between Fuji 7 and Uno when the temperature drops to (?i end temperature -) (by size '7 Predicted setting from Q 1111) Tl; Water cooling start 714 degrees T2; Water cooling end temperature TI- rl'12; Required cooling temperature of flange ΔTW; Furan-Zo of the web that decreases during water cooling, II7 degrees (estimated setting from empirical values) α: Coefficient of linear expansion E; Young's modulus R, In2; R1 in constant terms = O R2 = 400 In the present invention, the reason why the Q force 11j + 1 initial temperature of the outer surface of the 7 langes is set to below the transformation point is that starting cooling at a temperature higher than the Arl transformation point causes material defects, and , is set above 25 (1'U) because it becomes difficult to suppress the desired web waves.Furthermore, the web temperature f is set at 550°C to 1.00°C because 7 range temperature This is because, in relation to ,
As explained in FIG. 2, the temperature difference between the flange and the web is the key point, and it is desirable to set the cooling start temperature within the temperature range, taking into account the transformation range and all stresses. In the present invention, in order to make the temperature conditions suitable, the flange and web may be kept warm or heated within the allowable conditions of the present invention, or cooling may be added at times.
It is preferable to optimize the temperature conditions during the natural heat dissipation process during hot rolling. Now, regarding the above-mentioned direct contact press plate, if it is made of a heat insulating material, the contact area with the web may be wide, but from the viewpoint of mechanical strength, when using a metal material with high thermal conductivity, It is desirable that the contact area with the web be small. Therefore, in Example 1 (Article 11) 6 (Fig. 3), the contact protrusion (
Use the row or iJ, line or point J, or touch) to get the desired result! )is. Although it is better to have fewer contact areas and contact points, in order to achieve the goal of preventing web waves, it is better to have a wider distribution θ.Next, using the pressure plate The pressing force P (ton/,) of the pressed H type 6" rFq C 1 I 11 Length 9 is obtained by the following formula. , mm3)~v
, : Web thickness (scream) Also, in the present invention, the contact protrusion 33 a = 3 : 3
It was found that within the range where d maintains the linearity of 3 tmn 14 degrees as the amount of web bending, everything contacts the web and -C does not need to be present. Next, Table 1 below shows a comparison between an example of forced cooling on the outside of the flange and natural cooling (air cooling). The dimensions of the web-bound H-section steel in Table 1 are web height 598
The width of the flange is 96wn, the web 1 station is 6mm, the thickness of 7 lunges is 19mm, and the cooling water density is 195 l/m2r.
It is min. Next, an embodiment of the loading amount 1' according to the present invention will be explained. Figures 4 and 5 show a web tin-walled H-beam 38 that was hot-rolled by a rough and finishing mill and cut to a fixed size by a hot-saw machine. 1111 side view of the water cooling device and (1) side view, 39a, 39nr; 42a and 42b are piston ronds attached to the presser plates 41a and 41n, which are attached to the presser plates 40a and 41n together with the cylinders 43a and 43h, respectively.
40b to the contact protrusions 41a to 4]n to the H-shaped steel 3
The ability to impose on the web 44 of 8 is making money. The previous cylinders 43a and 43b are fixed to a highly rigid beam 46 having a reinforcing plate 45, and the beam 4
6 is supported by a support beam 47, the support beam 4
7 is rigidly supported by a support column 48. 43c~43f
Since this is a device similar to the suppression device represented by the piston and cylinder, the explanation will be omitted. A bit 49 is provided below the conveyor rolls 39 a r 39 n, and a lower pressing plate 40'b is supported on the working floor 50 of the bit 49 by the piston rod 42b1 cylinder 43b. There is. 51 indicates the base of the cylinder 43b. The conveyor wheels 39a+39b have a cantilever bearing device 52a. Since it is supported by the lower suppressing plate 40b, the vertical movement of the lower suppressing plate 40b is not hindered. 53a and 53b are cooling nozzle boxes on the outside of the flange, and a water supply pipe 54a. 54b is connected to the support surfaces 55a and 55b so that water can freely flow therethrough, and the support surfaces 55a and 55b are connected to the water supply main pipe 56a.
, 56b so as to be movable up and down. Therefore, even if the dimensions of the H-shaped steel 38 change and the flange d'' is different, the cooling nozzle box 53a can be placed in an appropriate position. You can bring 53bt. Also, Shirobako 55a
*If a telescopic water flow joint is used between s5b and water supply%' 54 a r 54 b, the cooling nozzle boxes 53a and 53b can be moved backwards by 111 degrees, so the web height of H type/A38 Even if the values are different, an appropriate 1%i distance 1lII can be maintained. 6 r i
/Ct, i water ssolei, air water spray, etc. must-have cooling IJ
Adopt appropriate measures depending on the situation. Now, the H-shaped steel 38 carried between the pressing plates 40a and 40b by the transport rolls 39a to 39n described in ^11.
In contrast, the two-part press plate 4 is in the standby position in advance.
0 a i, J: Cylinder 43a1 is lowered via piston rod 42 & fK, and at the same time lower part of suppression plate 4
0b is raised by the cylinder 43b1 and the piston rod 42b, and comes into contact with the upper and lower surfaces of the web 44 of the H-shaped steel 38, respectively, and a predetermined pressing force is applied to the web 44. Next, a cooling nozzle 1t53a is installed on the outer surface of the 7-run H-shaped steel 38.
Air/water llft'A'; is carried out via 53bi. It was a nuisance that this operator 1- could not be used at the same time or even if there was a slight delay in time. In Figures 6 and 7, the number of suppression plates is 1III1. 4 and 5, the contact projections 4, c, and 41 d are different from the long strip contact projections extending in the longitudinal direction of the web, as shown in FIGS. 4 and 5. The blade-shaped protrusions are fully formed and contact the web 44 from above and below in the width direction of the H-beam 38 between the conveyor rolls 39a to 39n. In FIGS. 6 and 7, those having the same numbers (the leading characters may be different) or the same symbols as those in FIGS. 4 and 5 have the same ν1j1:, so a description thereof will be omitted. In the apparatuses shown in FIGS. 6 and 7, the diameter of the transport roll is as small as possible, and a control device is added so that any number of cylinders can be operated simultaneously. As described in detail above, according to the method of the present invention, it is possible to provide a high-quality, economical web wide-walled H-beam steel.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are cross-sectional and vertical cross-sectional schematic diagrams of H-beam steel, and Figure 2 (a), (b), and (c) are H-beams.
Fig. 3 is an explanatory diagram of residual stress in the cooling process of shaped steel, Fig. 3 is an explanatory diagram of the implementation procedure of the method of the present invention, Figs.
Figures 6 and 8'X7 are side and front schematic views of the device with different bases (1): 1... web, 18... H-shaped eM, 2 A + 2
b...Cylinder, 3...Web wave, 4...Franz temperature, 5...Web temperature, 6...Flange temperature
17... Temperature difference between Franz and web, 8... Difference between flange and web 1 to 1 degree, 9° 16.21, 25.28...
・Neutral width 1, 10, 12° 17.20, 24.27...
・Tensile stress, 11, 14° 18.19, 22.26・
...Compressive stress, 13,15°23...Yield point, 29.
...II form, 30...web, 31 a, 3
l b ”・flange, 32 a , 32 b - direct contact type press plate, 33 a to 33 d... contact protrusion, 34
a, 34 b...-cooling nozzle box, 35a,
35b... Nozzle group, 36a, 36b... Pulp, 378° 37b... Water supply pipe. System 1 (b), ((2)
$30 JOJ/ff

Claims (1)

[Claims] A hot-rolled web thin-walled H section steel is heated to a Franz temperature of Ar.
l Transformation point or lower to 250°C or higher, web temperature 550°C or higher
A thin web that is characterized by the fact that in a temperature range of 100°C, the entire web is clamped by direct contact pressure extraction, the web is mechanically restrained, and the outer surface of the flange is forcibly cooled with water, thereby suppressing the generation of web waves. ■1 Method of manufacturing section steel.