JPS6011087B2 - Mobile hearth type heating furnace - Google Patents

Description

[Detailed description of the invention] This invention relates to a moving hearth heating arm.

A moving hearth type heating furnace such as a walking hearth furnace is generally used as a heating method for heating a steel billet prior to wire rod rolling.

In this heating furnace, it has become necessary to heat long steel billets due to the recent tendency to increase the unit weight of steel billets, and for example, heating of long and thin steel billets with a cross section of 12 degrees elevation angle and a length of about LOW is being carried out. However, when heating such a long piece of steel, the heating of the bottom surface (side of the hearth) and rear surface (side of the furnace inlet) of the steel piece is delayed near the preheating zone of the heating furnace, resulting in uneven heating. This causes bending of the steel piece. This bending increases as the steel billet advances toward the center of the furnace length, and as shown in FIG. This causes the steel pieces to bend and become extremely unstable, and may be caused by movement of the movable hearth 4 during conveyance, or during transfer of steel pieces between the movable hearth 4 and the fixed hearth 5 during this conveyance. , some pieces of steel rotate 90 degrees forward or backward and fall. This rolling causes the steel billets W to stick together as shown in Figure 2, and uneven heat generation occurs due to the delay in heating up at the stuck portions, so the furnace is heated to ensure the minimum temperature of the steel billet required for rolling. It is necessary to set the temperature high, which wastes fuel, and if there is a significant delay in raising the temperature of the steel billet, it becomes necessary to shut down while waiting for heating, which causes problems in subsequent processes. In addition, if the bending of the steel billet is particularly large, a phenomenon occurs in which the steel billet W jumps over the front steel billet W2 of another lot, as shown in FIG. 3, which causes the generation of foreign materials. This invention was made in view of the above points, and provides a moving hearth type heating furnace that can prevent steel billets from rolling in the heating furnace and solve all the conventional problems associated with this rolling. This is what we are trying to provide.

An embodiment of the present invention will be described below with reference to FIGS. 4 and 5.

In the figure, 1 is a heating furnace consisting of a walking hearth furnace, and 2
3 is a steel piece loading inlet, and 3 is a steel piece extraction port.

4a to 4f are movable hearths, which are driven by a known drive mechanism to draw rectangular or elliptical loci.

5a to 5e are fixed hearths.

The movable hearths 4c and 4d near the center of the furnace have raised parts 6 extending in the furnace length direction, and the fixed hearth 5c of the center of the furnace
Similarly, a raised portion 7 extending in the furnace length direction is provided.
The raised parts 6 and 7 are provided near the center of the furnace length, are made of a refractory material, and are fixedly fixed to the fixed hearth or the movable hearth, respectively. As shown in FIG. 4, the raised part 7 includes a steep slope part 8 with a length L that rises in the direction of progress of the steel billet, a horizontal surface part 9 with a length L2, and a horizontal part 9 that descends in the direction of progress of the steel billet. The raised portion 6 is provided with an inclined surface portion 10 having a length
It also has the same shape. When the billet W is heated in the heating furnace 1 having the above configuration, the billet charged into the furnace from the billet charging inlet 2 moves upward in the center and in the billet advancing direction as it progresses through the furnace. However, the lower surface of the central part of the steel slab is supported by the inclined surface part 8 of the raised part 6 or 7, and then the raised part 6 Alternatively, the lower surface of the center of the steel billet is supported by the horizontal surface portion 9 of 7.

Therefore, even if the piece of steel tries to roll or starts to roll, the central part and both ends are supported at three or more places by the movable hearth 4a, 4c, 4d, 4f or the fixed hearth 5a, 5c, 5e. This will prevent it from rolling over. As the temperature of the steel billet progresses, the temperature difference within the steel billet decreases and the steel billet softens, so that the steel billet that has reached the forehead slope portion 10 is transported so that the central portion of the steel billet becomes inclined at the raised portion 6 or 7. While being supported by the surface part, it descends due to its own weight, reducing the amount of curvature, and at this time, it is also prevented from rolling away from the inclined surface part. The amount of curvature of the steel billet that has passed through the inclined surface portion 10 is small, and when the billet is extracted from the steel billet extraction port 3, it is extracted almost in the shape of road material. The shape of the raised portions 6 and 7 is determined as appropriate depending on the amount of bending of the steel billet in the furnace and the growth condition of the bend. It may be formed to have

In addition, there may be a small gap between the upper surface of the raised part and the bent steel piece without rolling, so that the steel piece that is about to fall can be
The upper surface may have a shape that prevents it from rotating by more than 0 degrees. Furthermore, as a hearth in which the raised parts 6 and 7 are provided, for example, instead of providing the raised parts 7 on the fixed hearth 5c, the raised parts 7 may be provided on two fixed hearths 5b and 5d, or the raised parts 7 may be provided on two fixed hearths 5b, 5c, and 5d. The arrangement may be other than the above example, such as at three locations.In short, raised portions are provided so that the steel billet can be supported at a position closer to the center other than at both ends depending on the bending condition of the steel billet. do it. As explained above, according to the present invention, the fixed hearth and the movable hearth are provided with raised portions for supporting the central portion of the bent steel billet, so that the steel billet is not bent in the heating furnace. It is possible to prevent the steel pieces from rolling, prevent the occurrence of unevenness, and eliminate the occurrence of large variations in heating temperature due to the sticking of steel pieces, so there is no need to pause while waiting for heating, and the heating temperature, that is, the extraction temperature can be adjusted. Even if it is lowered, the subsequent rolling process will not be affected, and the fuel cost of the heating furnace can be reduced.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view of a heating furnace (corresponding to Figure 5) showing the curved state of steel in a conventional heating furnace, Figures 2 and 3 are illustrations of the rolled state of steel, and Figure 4 is FIG. 5 is a vertical cross-sectional view (cross-sectional view taken along the line B--B in FIG. 5) of a heating furnace showing an embodiment of the present invention, and FIG. 1... Heating furnace, 4a to 4f... Movable hearth,
5a-6e...Fixed hearth, 6,7...
Raised part. Juice 1 illustration Fang 2 illustrations 3 illustrations 4 illustrations 5 illustrations

Claims (1)

[Claims] 1. In a movable hearth type heating furnace equipped with a fixed hearth and a movable hearth, a raised part extending in the direction of the furnace length near the center of the furnace length is provided on the upper surface of the fixed hearth and the movable hearth near the center of the hearth width. A mobile hearth type heating furnace characterized by the following: