JP4777191B2 - Induction heating equipment installed in continuous annealing furnace with zinc bath - Google Patents

Description

The present invention relates to an induction heating apparatus installed in a continuous annealing furnace provided with a zinc bath, which is installed inside an inlet of a continuous annealing furnace provided with a zinc bath and induction-heats a steel sheet.

  Induction heating apparatuses that induction-heat steel plates using coils are conventionally known as disclosed in Patent Documents 1 and 2. In particular, if an induction heating device is installed at the inlet portion of the continuous annealing furnace, there is an advantage that the steel sheet can be rapidly heated and the degree of freedom in temperature control thereafter increases.

  In such an induction heating apparatus, it is important to highly insulate the coil in a high-temperature furnace atmosphere and to protect the coil from scale powder and zinc powder scattered in the furnace. For example, the atmospheric temperature is around 650 to 700 ° C. inside the inlet of a continuous annealing furnace for steel plates, and a high-frequency voltage is applied to the coil, so that reliable heat-resistant insulation is required. Also, for example, fine zinc powder with a diameter of about 100 μm is scattered inside the continuous annealing furnace of the hot dip galvanizing equipment. When this reaches the coil surface of the water-cooled structure, water due to condensation caused by water-cooled cooling water when the operation is stopped At the same time, a short circuit occurs to lower the insulation resistance, and the induction heating apparatus cannot be operated.

For this reason, as shown in Patent Documents 1 and 2, conventionally, there has been devised to protect the coil by applying a heat-insulating castable refractory or alumina ceramic on the coil surface. It is not considered enough. In addition, as shown in Patent Document 3, the entry of zinc powder from the outside is also prevented by increasing the pressure in the case housing the coil. However, although the induction heating device of Patent Document 3 is an outside furnace installation type, internal pressurization is possible, but when the induction heating device is installed in the furnace, it affects the furnace internal pressure, so the pressurization method is adopted. I couldn't.
JP-A-2005-156124 JP 2006-169603 A JP-A-6-88194

The present invention solves the above-mentioned conventional problems, can highly insulate the coil in a high-temperature furnace atmosphere, and can protect the coil from a decrease in insulation due to zinc powder scattered in the furnace. An object of the present invention is to provide a continuous annealing furnace installation type induction heating apparatus provided with a zinc bath .

The present invention was made to solve the above problems, the surface of the water-cooled coil body for induction heating the steel sheet that entered the heating furnace in which zinc powder is scattered in the furnace, a heat-resistant insulating paint layer, a varnish layer, The ceramic fiber layers are protected by sequentially lining them. The heat-resistant insulating paint layer is preferably a paint layer containing ceramic particles, and the ceramic fiber layer is a ceramic fiber layer containing crystalline alumina fibers or a ceramic fiber layer containing inorganic binder and crystalline alumina fibers. It is preferable. Furthermore, it is preferable to adhere the ceramic fiber layer to the surface of the varnish layer with a heat-resistant inorganic adhesive.

The induction heating apparatus installed in the continuous annealing furnace provided with the zinc bath of the present invention protected the surface of the water-cooled coil body by sequentially lining a heat-resistant insulating paint layer, a varnish layer, and a ceramic fiber layer. Thus, the synergistic effect of these three layers can exhibit stable insulation performance even in a high temperature atmosphere of around 700 ° C. In addition, the combination of the heat-resistant insulating paint layer and the varnish layer provides waterproofness, and the combination of these layers can completely prevent the zinc powder from reaching the coil surface. It is possible to prevent a short circuit caused by this and an insulation failure caused thereby. Furthermore, since there is a varnish layer in the middle, there is an advantage that the adhesion of the ceramic fiber layer is good and the workability is excellent.

Preferred embodiments of the present invention are shown below.
FIG. 1 is a schematic diagram of a continuous annealing furnace 1 for steel sheets, 2 is an entrance-side looper, and 3 is a continuous annealing furnace provided with a zinc bath provided inside an inlet of a continuous annealing furnace 1 provided with a zinc bath . An installation type induction heating device 4 is a zinc bath provided on the outlet side of the continuous annealing furnace 1. The steel sheet is rapidly heated by the induction heating apparatus 3 installed in the continuous annealing furnace provided with this zinc bath, and is subjected to predetermined annealing inside the continuous annealing furnace 1 to be hot dip galvanized. As described above, the furnace atmosphere temperature at the installation position of the continuous annealing furnace installation type induction heating apparatus 3 provided with the zinc bath is about 700 ° C., although it varies depending on the type of steel sheet.

The induction heating apparatus 3 installed in the continuous annealing furnace provided with this zinc bath is provided with a pair of coils 5 sandwiching a steel plate passage extending in the vertical direction as shown in FIG. It is held by the rigid member 7 via the heat insulating material 6. The periphery is surrounded by a shield plate 8 for preventing leakage of magnetic flux, and a partition 9 for preventing zinc powder from entering is provided between the shield plate 8 and the coil 5. The partition 9 is made of, for example, a twilled alumina cloth.

  FIG. 3 is an enlarged cross-sectional view of a portion of the coil 5, and 10 is a coil body for induction heating. The coil body has a water cooling structure including a plurality of cooling water flow paths 11 therein, and is connected to a high-frequency power source (not shown), and induction heating of the steel sheet is the same as in the prior art. However, the present invention is characterized by the lining structure on the surface of the coil body 10. That is, in the present invention, the surface of the coil body 10 is lined in three layers by the heat-resistant insulating paint layer 12, the varnish layer 13, and the ceramic fiber layer 14.

  The heat-resistant insulating paint layer 12 is formed by lining an insulating paint whose heat resistance is improved by containing ceramic particles on the surface of the coil body 10, and is commercially available, for example, from Otatake Serum Co., Ltd. under the trade name Pyrocoat. The heat-resistant insulating paint that can be used. This is a paint with improved heat resistance and insulation by mixing alumina particles. Insulating paints containing ceramics commercially available from Toa Gosei Co., Ltd. under the trade name Aron Ceramics can also be used. Since these are ceramicized by heating and have heat resistance of 1000 ° C. or higher, they exhibit complete insulation even in a furnace at around 700 ° C.

  The varnish layer 13 is obtained by lining an insulating varnish conventionally used as an insulating paint for electrical products on the surface of the heat-resistant insulating paint layer 12. The varnish layer 13 alone exhibits insulating properties, but when used alone, it is inferior in water resistance, so that it can be combined with the heat-resistant insulating coating layer 12 to have both insulating properties and water resistance. The varnish layer 13 also has a role of improving the workability by improving the adhesion of the ceramic fiber layer 14 to be lined thereon. This varnish layer 13 can be further improved in insulation properties by coating twice.

The ceramic fiber layer 14 is a layer for protecting the coil body 10 from a high temperature atmosphere and preventing the zinc powder from entering. This ceramic fiber layer 14 is preferably an alumina fiber layer containing crystalline alumina fibers from the viewpoint of heat resistance. For example, an SC blanket (Al ₂ O ₃ : 46 to 72%) from Nippon Kayaku Thermal Ceramics Co., Ltd. The thing containing the crystalline alumina fiber marketed with a brand name can be used. This is a blanket-like heat insulating material having an average fiber diameter of 3 μm and a thermal conductivity at 700 ° C. of not more than 02 W / m · K. You can also use crystalline alumina fibers sold by the company under the trade name SC wet felt, but this is a thermal insulation material in which an SC blanket is impregnated with an inorganic binder.

  The lining of the ceramic fiber layer 14 can be performed using the adhesiveness of the varnish layer 13, but it is preferable to use a heat-resistant inorganic adhesive. As the heat-resistant inorganic adhesive, it is possible to use the above-mentioned Aron ceramics manufactured by Toa Gosei Co., Ltd. or the silica-alumina based inorganic adhesive marketed under the trade name Thermodyne from Nippon Kayaku Thermal Ceramics Co., Ltd. . When these heat-resistant inorganic adhesives are baked at a high temperature, they become a ceramic and become a substance having heat resistance exceeding 1000 ° C., and therefore, peeling of the ceramic fiber layer 14 can be prevented.

  As described above, in the present invention, the surface of the coil body 10 is lined into three layers by the heat-resistant insulating paint layer 12, the varnish layer 13, and the ceramic fiber layer 14, and the heat-resistant insulating paint layer 12 and the varnish layer 13 Insulation and water resistance are secured, and further, the ceramic fiber layer 14 enhances heat resistance and prevents the zinc powder from entering. In addition, the varnish layer 13 enhances the insulating properties and enhances the adhesiveness of the ceramic fiber layer 14.

For this reason, the continuous annealing furnace installation type induction heating apparatus provided with the zinc bath of the present invention can exhibit stable insulation performance even in a high temperature atmosphere of around 700 ° C. Moreover, since the ingress of water and zinc powder can be prevented, a short circuit due to the zinc powder and an insulation failure caused thereby can be prevented, and a stable operation can be performed over a long period of time.

The induction heating apparatus installed in the continuous annealing furnace provided with the zinc bath of the present invention was installed inside the inlet of the continuous annealing furnace of the steel sheet installed on the entry side of the hot dip galvanizing line. The coil body is water-cooled. The surface is coated with “Pyrocoat”, a heat-resistant insulating paint from Otatake Serum Co., Ltd., and then a commercially available varnish is applied. Using a certain “Thermodyne”, a wet felt made of a crystalline alumina blanket commercially available under the trade name of SC Blanket from Shin-Nika Thermal Ceramics Co., Ltd. was bonded.

Conventional induction furnaces installed in the furnace protect the surface of the coil body with a heat-insulating castable refractory and require lining repairs twice a year to prevent deterioration of the insulation due to the ingress of zinc powder. I was trying. In contrast, the induction annealing apparatus installed in the continuous annealing furnace provided with the zinc bath of the present invention has passed more than one year without any lining repair after installation, but there are still abnormalities such as a decrease in insulation. No durability was confirmed.

It is a schematic diagram of the continuous annealing furnace of a steel plate. It is sectional drawing of the continuous annealing furnace installation type induction heating apparatus provided with the zinc bath . It is an expanded sectional view of a coil part.

DESCRIPTION OF SYMBOLS 1 Continuous annealing furnace 2 Entry side looper 3 Induction heating apparatus installed in continuous annealing furnace provided with zinc bath 4 Zinc bath 5 Coil 6 Heat insulating material 7 Rigid member 8 Shield plate 9 Partition 10 Coil body 11 Cooling water flow path 12 Heat insulation Paint layer 13 Varnish layer 14 Ceramic fiber layer

Claims (4)

The surface of the water-cooled coil body that inductively heats the steel sheet that entered the furnace where zinc powder is scattered in the furnace is protected by sequentially lining the heat-resistant insulating paint layer, varnish layer, and ceramic fiber layer. An induction heating apparatus installed in a continuous annealing furnace provided with a characteristic zinc bath . 2. The induction heating apparatus in a continuous annealing furnace provided with a zinc bath according to claim 1, wherein the heat-resistant insulating paint layer is a paint layer containing ceramic particles. The ceramic fiber layer is a ceramic fiber layer containing crystalline alumina fibers or a ceramic fiber layer containing inorganic binder and crystalline alumina fibers, and installed in a continuous annealing furnace provided with a zinc bath according to claim 1 Mold induction heating device. The induction heating apparatus in a continuous annealing furnace provided with a zinc bath according to claim 1, wherein the ceramic fiber layer is bonded to the surface of the varnish layer with a heat-resistant inorganic adhesive.

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