JPH05449B2 - - Google Patents

Description

[Detailed Description of the Invention] <Object of the Invention> Industrial Field of Use The present invention relates to a web heating device for rolling H-section steel, and more specifically, the present invention relates to a web heating device for rolling H-section steel, and more specifically, the present invention relates to a web heating device for rolling an H-section steel, and more specifically, the present invention relates to a web heating device for rolling an H-section steel. This relates to a web heating device for rolling shaped steel.

BACKGROUND ART In general, the cross-sectional shape of an H-section steel is such that the web thickness is smaller than the flange thickness and is very small compared to the web height. for example,
When an H-beam steel has a web thickness of 1/80 or less of the web height, the web thickness becomes very small, so the web temperature immediately after finishing rolling decreases and is often below the Ar ₃ transformation point. Furthermore, the finish rolling itself is two-layer area rolling (austenite + ferrite).
Therefore, it is not possible to obtain a predetermined rough metal texture, and the mechanical properties of the rolled material deteriorate. Specifically, tensile strength and tensile strength increase, elongation decreases significantly, and mechanical properties become low in toughness, making straightening and bending difficult, and cracking near the boundary area between the web and flange during straightening and bending. In some cases, this may occur.

In order to prevent the deterioration of mechanical properties and structure due to this decrease in web temperature, induction heating of the H-section steel web during rolling may be considered.
No. 56-152928 and Japanese Patent Application No. 60-167068 have been proposed.

However, although these methods are aimed at heating the web, it has been found that the flanges are also heated due to leakage magnetic flux during induction heating.

To prevent this, it is generally known to install a shield ring close to the induction coil, but since the purpose of the shield ring is to reduce leakage magnetic flux from the coil, until now the coil dimensions have not been adjusted. Therefore, the dimensions of the shield ring had been determined.

However, for H-section steel, it is desirable not only to reduce the temperature difference between the web and the flange, but also to roll the inside of the flange at a uniform temperature. Therefore,
Even when web heating and flange water cooling are combined, it is difficult to maintain a uniform temperature within the section during rolling.

Problems to be Solved by the Invention The present invention aims to solve these problems, and specifically, it focuses on the characteristics of leakage magnetic flux of the induction coil of an induction heating device that heats a web, and the prevention of leakage magnetic flux to the flange. An object of the present invention is to provide a web heating device during rolling of an H-section steel, which makes the temperature distribution of the flange in the H-section steel uniform by combining a shield ring for the purpose of rolling the H-section steel.

<Structure of the Invention> Means for Solving the Problems and Their Effects The structure and effects of the present invention will be explained below with reference to the drawings.

FIG. 1 is a perspective view showing a part of an example of the web heating device according to the present invention in cross section, and FIG. 2 is a lithography showing the flange temperature distribution immediately after rolling.
FIG. 3 is a graph showing the temperature distribution of the flange due to leakage magnetic flux during induction heating and the effect of the shield ring, and FIG.
Figure b is a graph showing the temperature distribution of the flange at that time.

In FIG. 1, reference numeral 2 indicates a web of H-shaped steel 1;
3 indicates a flange. A pair of induction coils 4 and 4' are arranged above and below the web 2, and the induction coil is composed of a coil 5 and an iron core 6.

A shield ring 7 consisting of a water cooling coil for circulating water in a hollow pipe is installed between the induction coil 4 and the flange 3. This shield ring 7 connects both ends of the upper and lower two conductive pipes 8, 8' made of steel, copper, etc. with two left and right conductive flexible pipes 9,
9', the effective height h is variable, and the coils 2 are provided so as to cover the entire length thereof. The height of the shield ring 7 is configured to be movable while detecting its position with a cylinder or the like (not shown), and is determined from the temperature distribution of the flange 3 before heating.

As shown in Figure 2, the temperature distribution of the H-shaped steel flange immediately after leaving the universal finishing mill is high, with the temperature centered around the center of the flange width B, that is, the R part, and the temperature at the flange ends Et and Eb. is lower, and moreover, the upper end Et of the flange is lower than the lower end Eb. Therefore,
In order to reduce residual stress, the central part of the flange and
It is necessary to reduce the temperature difference between Et and Eb parts.

On the other hand, when the gap between the coil 5 and the flange 3 is small, the flange is heated by leakage magnetic flux during induction heating of the web, and as shown by the solid line in FIG. 3, the temperature rise increases closer to the edge. This phenomenon is due to the fact that the current is dense at the flange end, and tends to occur when the gap between the coil and flange is less than half the width of the coil.

Furthermore, if a shield ring is provided between the coil 5 and the flange 3 to control the leakage magnetic flux, the temperature at both ends of the flange Et, Eb decreases as shown by the dotted line in FIG. Therefore, by controlling the effective height h of the shield ring, it is possible to control the temperatures of Et and Eb.

As described above, the temperature distribution of the flange can be made uniform by changing the effective height h of the shield ring and controlling the leakage magnetic flux of the induction coil.

That is, the temperature distribution of the H-section steel immediately after leaving the universal finishing mill was measured with a scanning thermometer,
After moving and positioning the shield ring 7 using a drive system such as a cylinder based on the temperature distribution of the flange, the H-section steel web portion 2 is heated by induction, thereby making it possible to make the temperature distribution of the flange uniform. Furthermore, if you combine this with the flange water cooling method,
Uniformity is possible due to temperature distribution.

Example The present invention will be further explained below based on embodiments.

As a result of measuring the temperature distribution of the H-beam immediately after leaving the universal finishing mill with a scanning thermometer,
The center part of the flange (R part) as shown by the solid line in Figure b.
It was found that the temperature of the flange is high, the temperature of both ends of the flange Et and Eb is low, and the temperature of the upper end of the flange Et is lower than the temperature of the lower end Eb. Therefore, as shown in FIG.
The effective height h of the lower shield ring 7' is made small, and the lower shield ring 7'
Induction heating of the H-section steel web was performed while controlling the leakage magnetic flux by adjusting the effective height h' of the flange to the flange width.

Through the above operations, the temperature distribution throughout the flange was improved as shown by the dashed line in FIG.

<Effects of the Invention> As explained above, the present invention connects both ends of two conductive pipes between an induction coil and a flange of an induction heating device that heats a web of H-section steel using a conductive flexible pipe. A web heating device is characterized in that it is provided with a shield ring whose effective height can be adjusted.The present invention utilizes leakage magnetic flux effectively to heat the web and at the same time equalize the temperature distribution of the flange. As a result, it has become possible to significantly reduce residual stress within the shaped steel.

Furthermore, since the position of the shield ring can be made to correspond to each size, it is now possible to perform optimal web heating for each size and to make it possible to make the flange temperature uniform.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing a part of an example of the web heating device according to the present invention in cross section, Fig. 2 is a graph showing the flange temperature distribution immediately after rolling, and Fig. 3 is a graph showing the flange temperature distribution due to leakage magnetic flux during induction heating. FIG. 4a is a graph showing the temperature distribution and the effect of the shield ring. FIG. 4a is an explanatory diagram showing the arrangement of the shield ring in an embodiment of the present invention, and FIG. 4b is a graph showing the temperature distribution of the flange at that time. Code, 1... Shape steel, 2... Web, 3... Flange, 4... Induction coil, 5... Coil, 6...
Iron core, 7... Shield ring, 8... Conductive pipe, 9... Conductive flexible pipe.

Claims (1)

[Claims] 1. A shield ring is installed between the induction coil and flange of an induction heating device that heats a web of H-beam steel, with the ends of two conductive pipes connected by a conductive flexible pipe so that the effective height can be adjusted. 1. A web heating device for rolling H-shaped steel.