JPS6321551Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a heat treatment furnace for hot strips (strip steel sheets) that are hot-rolled and then wound into coils using a winder.

Although the temperature of the outer and inner circumference of a coiled hot strip immediately after winding usually decreases due to the cooling effect, the average temperature is close to the winding temperature, and it has high sensible heat. There is. today,
In order to heat-treat the wound coiled strip at low cost, the hot strip is wound at a high temperature and heat-treated using the sensible heat of the coil itself. However, since there is a temperature difference in the width direction and circumferential direction of the coiled hot strip when it is wound, uneven heat treatment occurs. Therefore, attempts have been made to uniformize the temperature of the entire coil in a short time using the sensible heat of the coil by transporting the coil immediately after winding into a heat treatment furnace and heating and keeping it warm.

A heat treatment furnace usually consists of an insulating chamber lined with a heat insulating material or a heat insulating material, and is provided with a heating device if necessary. In addition, heat transfer related to coiled hot strips in a heat insulation device is dominated by heat conduction within the steel, convection with the furnace atmosphere, and heat radiation with the furnace body and combustion flame. It is characterized by the amount of heat transfer being several times larger than that in the radial (laminated) direction.

(Prior Art) The heat treatment of such a coiled high temperature strip is described, for example, in Japanese Patent Application Laid-open No. 58-37128.
Heat treatment is performed with the coiled strip in a vertical position. As shown in Figure 1, coil 1
When the coil is heat-treated in a vertical position, one of the coil end surfaces (laminated surfaces) will be installed on the furnace bottom 3, and the other end surface facing the furnace inner wall 2 and the outer periphery will receive strong heat radiation. However, since heat radiation from the inner wall of the furnace is inhibited, temperature differences tend to occur in the width direction of the coil. Therefore,
When a hot coil is rapidly heated and soaked for several hours immediately after being wound, a temperature difference occurs due to the temperature distribution in the coil width direction and the heat flow distribution in the furnace that the hot coil has at the time of winding. In order to uniformly heat the product, it is necessary to extend the heat retention time.

(Purpose of the present invention) The present invention proposes a heating/warming device that eliminates the uneven heat of the coil during the short-time heat treatment as described above and heat-treats the coiled hot strip quickly and uniformly.

(Structure and operation of the invention) As shown in FIG. 2, by supporting the coil 1 in a down-end state (horizontal state), the heat transfer conditions are equal on both end faces of the coil. Thereby, the temperature difference in the width direction of the coil can be reduced. However, the temperature of the lower part B of the coil 1 is lower than the temperature of the upper part A and the end face D, and a temperature distribution occurs due to the difference in the coil parts. This is because the upper part A and the end part D of the coil face the relatively wide inner wall 2 of the furnace and the space (atmosphere) and can receive strong heat radiation, while the lower part B of the coil faces the furnace bottom 2.
This is due to the fact that the coil is in contact with the inner wall of the coil, and the area of the facing inner wall of the furnace is narrower than that of the upper part A and the end D of the coil. Furthermore, in the above installation method, when heating with the burner 4, areas close to the combustion flame tend to be overheated due to the influence of heat radiation from the flame, and there is a risk of promoting uneven heating.

Therefore, in the present invention, as shown in FIGS. 3 and 4, during heat treatment of the coiled strip, the coiled strip 1 is raised above the furnace bottom 3, and the combustion flame from the burner 4 is placed at a position higher than the burner opening 4. It is characterized by being supported by a pedestal 5 having a circulation space of
The area of the inner wall of the furnace that the lower part B of the coil faces is wider than that of the lower part B of the coil, making it possible to receive the same degree of radiant heat transfer as the upper part A and end part D of the coil, and reducing the influence of direct heat radiation from the combustion flame. This can prevent certain parts of the coil from overheating.
Therefore, the temperature of the entire coil can be made uniform in a short time. In the figure, 6 indicates an exhaust port.

Figure 5a schematically shows the temperature difference in the width direction of the coil 60 minutes after the start of heating when the coil was heat treated using the heat treatment furnace for the coiled hot strip shown in Figures 3 and 4. For comparison, a schematic diagram b of the temperature difference in the coil width direction when the pedestal 5 is removed and the coil is grounded is also included. According to the figure, the maximum temperature difference ΔTmax in the coil width direction is 90°C in the comparative example, whereas ΔTmax = 50°C in the present invention, indicating that the coiled hot strip can be heated uniformly in a short time.

(Effects of the invention) As described above, the invention has the effect of uniformly heating the coiled hot strip in a short time.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a normal coil heat-retention furnace, Fig. 2 is an explanatory diagram of a coil horizontal heat-retention furnace with a heating burner, and Figs. 3 and 4 are front and side views of the heat treatment furnace of the present invention. Both drawings show the furnace wall (ceiling) in cross section. FIG. 5 is a schematic diagram of the temperature difference in the strip width direction of a coil heat-treated for a predetermined period of time. 1; Coil, 2; Furnace wall, 4; Burner, 5; Frame.

Claims (1)

[Scope of utility model registration request] In a burner-type heat treatment furnace in which a coil in the furnace is heated by a burner, the coil is placed in a down-end shape on a pedestal having a circulation space for the burner combustion gas flame, and the burner is lower than the coil. A high-temperature strip coil heat treatment furnace is installed at the location.