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JP-7855305-B2 - Continuous heat treatment furnace

JP7855305B2JP 7855305 B2JP7855305 B2JP 7855305B2JP-7855305-B2

Inventors

  • 杉岡 信幸

Assignees

  • 中外炉工業株式会社

Dates

Publication Date
20260508
Application Date
20231027

Claims (4)

  1. A continuous heat treatment furnace is characterized in that a long metal strip is driven inside the furnace and the metal strip is heat-treated in a flow of gas inside the furnace that flows toward an exhaust pipe from which fuel is burned inside the furnace by a combustion device, and a support roller for stabilizing the movement of the metal strip inside the furnace is provided only at a position downstream of the combustion device in the direction of metal strip movement and upstream of the gas flow inside the furnace, and an inert gas supply device is provided at a position upstream of the support roller in the direction of gas flow inside the furnace for supplying inert gas.
  2. The continuous heat treatment furnace according to claim 1 is characterized in that it is a vertical type in which the metal strip is moved vertically within a furnace.
  3. A continuous heat treatment furnace according to claim 1, characterized in that a support roller having a carbon sleeve on its outer surface is used as the support roller.
  4. A continuous heat treatment furnace is characterized in that, in which a long metal strip is driven in the furnace and the metal strip is heated in the flow of gas inside the furnace that flows toward an exhaust pipe from which fuel is burned in the furnace by a combustion device, a support roller for stabilizing the movement of the metal strip in the furnace is provided only at a position downstream of the combustion device in the direction of metal strip movement and upstream of the direction of gas flow inside the furnace, an inert gas supply device is provided at a position upstream of the support roller in the direction of gas flow inside the furnace for supplying inert gas, an oxygen concentration detection device is provided at a position downstream of the support roller in the direction of gas flow inside the furnace for detecting the oxygen concentration inside the furnace, the oxygen concentration inside the furnace detected by the oxygen concentration detection device is output to a control device, and the control device controls the supply of inert gas to the furnace by the inert gas supply device.

Description

This invention relates to a continuous heat treatment furnace that heats a long metal strip by running it through the furnace and burning fuel in the furnace using a combustion device. In particular, it is characterized by the fact that, when burning fuel in the furnace using a combustion device and heating the long metal strip by running it through the furnace, support rollers are provided to ensure stable movement of the metal strip without damaging it. Conventionally, as shown in Patent Document 1 and others, a continuous heat treatment furnace is known in which a metal strip made of a long steel plate or the like is moved vertically within a furnace while a fuel is burned in the furnace using a combustion device to perform heat treatment. Furthermore, in continuous heat treatment furnaces, as shown in Patent Document 2, support rollers are provided on both sides of the moving metal strip to guide it and in contact with the metal strip, in order to ensure that the metal strip moves stably within the furnace. Furthermore, as shown in Patent Document 2, the support rollers used include support rollers with a carbon sleeve made of graphite or the like on their outer surface, and metal support rollers made of stainless steel or the like. However, in a continuous heat treatment furnace where fuel is burned inside the furnace using a combustion device as described above, when a metal support roller is used as the support roller, the oxygen remaining in the combustion exhaust gas from the burned fuel oxidizes the surface of the metal support roller, causing oxide deposits. These oxide deposits can then damage the surface of the metal strip being transported. Furthermore, in a continuous heat treatment furnace in which fuel is burned inside the furnace by a combustion device as described above, if a support roller with a carbon sleeve on its outer surface is used as the support roller, as shown in Patent Documents 3 and 4, the surface will not oxidize and oxides will not accumulate. However, when the temperature inside the furnace becomes high, the carbon in the carbon sleeve reacts with oxygen contained in the combustion exhaust gas from burning the fuel and sublimes into CO or CO2 , causing the diameter of the support roller to decrease, which leads to the problem that the metal strip cannot be guided properly. Japanese Patent Publication No. 2010-202959Japanese Patent Application Publication No. 8-269579Japanese Patent Application Publication No. 6-322436Japanese Unexamined Patent Publication No. 7-113115 This is a schematic diagram illustrating a continuous heat treatment furnace according to an embodiment of the present invention, in which a metal strip is heated by being moved from top to bottom within a furnace that is arranged vertically.This is an enlarged cross-sectional explanatory diagram showing a continuous heat treatment furnace according to the above embodiment, in which a metal strip is heat-treated in the gas flow inside the furnace that flows toward the exhaust pipe after a combustion device burns fuel inside the furnace, an inert gas supply device that supplies inert gas to a position upstream of the support roller in the direction of gas flow inside the furnace, and an oxygen concentration detection device that detects the oxygen concentration inside the furnace at a position downstream of the support roller in the direction of gas flow inside the furnace, and a control device that controls the inert gas supplied from the inert gas supply device based on the oxygen concentration detected by the oxygen concentration detection device.This is a schematic plan view showing an example of a support roller with a carbon sleeve on its outer surface in a continuous heat treatment furnace according to the above embodiment. The following describes a continuous heat treatment furnace according to an embodiment of the present invention, based on the attached drawings. However, the continuous heat treatment furnace according to this invention is not limited to those shown in the following embodiments, and can be modified as appropriate without altering the essence of the invention. In this embodiment of the continuous heat treatment furnace, as shown in Figures 1 and 2, a long metal strip S, such as a stainless steel strip, is transported by being wound up by a winding device (not shown) located in the lower process of the apparatus. Its orientation is changed downward by an introduction roller 1, and while preventing the outflow of the atmosphere inside the furnace 10 and the intrusion of outside air by a seal roller 14, it is introduced into the vertically oriented furnace 10. Fuel is burned inside the furnace 10 by each combustion device 20 located in the heating section 11 at the top of the furnace 10, thereby heating the metal strip S introduced into the furnace 10. Here, the combustion exhaust gas generated by each combustion device 20 is exhausted from the upper exhaust pipe 13, creating a gas flow