Scarfer device

Abstract

To provide a scarfer device that reduces the heat load on the side surface of the upper manifold and reduces the risk of gas leaks. [Solution] The scarfer apparatus according to the present invention comprises an upper manifold for supplying flammable gas, preheating oxygen, and cutting oxygen; a side nozzle unit disposed on the side of the upper manifold for cutting the surface of a steel billet being transported using the flammable gas, preheating oxygen, and cutting oxygen supplied from the upper manifold; and a plate-shaped frame for holding the upper manifold, disposed on the exit side in the steel billet transport direction of the upper manifold and the side nozzle unit, wherein the scarfer apparatus includes a heat shield plate installed in the gap formed by the upper manifold, the side nozzle unit, and the frame to suppress the intrusion of heat generated when cutting the surface of the steel billet into the side of the upper manifold.

Description

[Technical Field]

[0001] The present invention relates to a scarfer device. [Background Art]

[0002] Surface defects such as flaws and inclusion entrapment occur on the surface of steel slabs manufactured by continuous casting. When removing these surface defects, a scarfer device (a scarfing apparatus) as described in Patent Documents 1 and 2 is used. A scarfer device is an apparatus that blows combustible gas and oxygen onto a steel slab to thermochemically remove surface defects, and includes a nozzle unit that blows combustible gas and oxygen. In addition, alongside each nozzle unit, a stainless steel block called a manifold that supplies combustible gas and oxygen to the nozzle unit is installed, and a cap fitted with a rubber O-ring for closing the end of a fluid path is provided on the side surface of the manifold.

[0003] When removing surface defects from a steel slab using a scarfer device, first, preheating treatment is performed: combustible gas and preheating oxygen are blown onto the steel slab to combust the combustible gas, and the heat of combustion forms a molten portion on a part of the surface of the steel slab. Then, the steel slab is conveyed while blowing scarfing oxygen, and the molten portion is reacted with the scarfing oxygen using the heat of the molten portion as a heat source. By this reaction heat, the surface of the steel slab is melted, and surface defects are removed. In this way, the scarfer device thermochemically removes surface defects. For this reason, nozzle units and the like that are subjected to high thermal load are water-cooled. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Publication No. 2021-16867 [Patent Document 2] Japanese Unexamined Patent Publication No. 09-168862 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] The inventors of the present invention discovered that the side surface of the upper manifold, which was previously thought to have a low thermal load, becomes hot during operation. Conventionally, improvements have been made to the surface quality of steel billets by changing the components and cutting methods of the scarfing device, but no improvements have been made to reduce the thermal load on the side surface of the upper manifold, and countermeasures have been taken by periodically replacing the parts that receive the thermal load. When the side surface of the upper manifold becomes hot, the O-ring of the cap that seals the end of the fluid path deteriorates, which can cause gas leaks, so heat protection measures are necessary.

[0006] The present invention was made to solve the above problems, and its objective is to provide a scarfer device that can reduce the heat load on the side surface of the upper manifold and reduce the risk of gas leakage. [Means for solving the problem]

[0007] The scarfer apparatus according to the present invention comprises: an upper manifold for supplying flammable gas, preheating oxygen, and cutting oxygen; a side nozzle unit disposed on the side of the upper manifold for cutting the surface of a steel slab being transported using the flammable gas, preheating oxygen, and cutting oxygen supplied from the upper manifold; and a plate-shaped frame for holding the upper manifold, disposed on the exit side in the steel slab transport direction of the upper manifold and the side nozzle unit, wherein the scarfer apparatus includes a heat shield plate installed in the gap formed by the upper manifold, the side nozzle unit, and the frame to suppress the intrusion of heat generated when cutting the surface of the steel slab into the side of the upper manifold.

[0008] When the side nozzle unit is used to cut the surface of the steel billet, it is preferable to preheat the steel billet using a near-end start method. [Effects of the Invention]

[0009] According to the scarfer device of the present invention, the heat load on the side surface of the upper manifold can be reduced, thereby reducing the risk of gas leakage. [Brief explanation of the drawing]

[0010] [Figure 1] Figure 1 shows the configuration of a conventional scarfer device. [Figure 2] Figure 2 shows the configuration of the upper manifold shown in Figure 1. [Figure 3] Figure 3 is a diagram illustrating the method for preheating steel billets. [Figure 4] Figure 4 shows the gap between the upper manifold, the left side nozzle unit, and the frame. [Figure 5] Figure 5 shows the configuration of the heat shield. [Figure 6] Figure 6 shows the installation positions of the heat shields. [Figure 7] Figure 7 shows the results of measuring the ambient temperature on the side of the upper manifold when one side of a steel billet is being cut by melting, before and after the installation of the heat shield. [Modes for carrying out the invention]

[0011] The scarfer apparatus according to the present invention will be described below with reference to the drawings.

[0012] [Conventional scarfer device configuration] First, the configuration of a conventional scarfer device will be described with reference to Figures 1 and 2.

[0013] Figure 1 shows the configuration of a conventional scarfer device. Figure 2 shows the configuration of the upper manifold 2 shown in Figure 1. As shown in Figure 1, the conventional scarfer device 1 is a device that removes surface defects from a steel billet S conveyed in the direction of the arrow by a conveyor roll R, and comprises an upper manifold 2, an upper nozzle unit 3, a left side nozzle unit 4, and a frame 5.

[0014] As shown in Fig. 2, the upper manifold 2 is formed of a stainless steel block, and has a structure in which pipes for flammable gas, preheating oxygen, scarfing oxygen and cooling water penetrate through the side portion. Specifically, the upper manifold 2 includes flammable gas pipes 21a and 21b to which flammable gas is supplied, an oxygen pipe 22a to which preheating oxygen is supplied, an oxygen pipe 22b to which scarfing oxygen is supplied, a cooling pipe 23 to which cooling water for cooling the upper manifold 2 and the upper nozzle unit 3 is supplied, and caps 24a to 24d each having a rubber O-ring that seals an end of each pipe.

[0015] Returning to Fig. 1. The upper nozzle unit 3 blows flammable gas and preheating oxygen supplied from the upper manifold 2 onto a steel slab S to combust fuel gas, and performs a preheating treatment of forming a molten portion on a part of the surface of the steel slab S by the combustion heat. Further, the upper nozzle unit 3 blows the scarfing oxygen supplied from the upper manifold 2 onto the steel slab S, and causes the molten portion to react with the scarfing oxygen using the heat of the molten portion as a heat source, thereby melting the surface of the steel slab S and removing surface defects.

[0016] The left side nozzle unit 4 is disposed at a position facing the side surface of the steel slab S, and removes surface defects on the side surface of the steel slab S by operating in the same manner as the upper nozzle unit 3.

[0017] The frame 5 is formed of a plate-shaped member, and is disposed on an exit side of the steel slab S so as to face back surfaces of the upper manifold 2, the upper nozzle unit 3, and the left side nozzle unit 4. The frame 5 holds the upper manifold 2 and the upper nozzle unit 3.

[0018] [Configuration of Scarfer Device of the Present Invention] Next, the configuration of the scarfing device according to the present invention will be described with reference to Figs. 3 to 7.

[0019] There are two preheating methods for a steel slab S: the end start method shown in FIG. 3(a) and the near-end start method shown in FIG. 3(b). Specifically, the end start method shown in FIG. 3(a) preheats the end face of the steel slab S, and the near-end start method shown in FIG. 3(b) preheats a position spaced apart from the end face of the steel slab S. As a result of intensive studies, the inventors of the present invention have found that: (i) in the end start method, the preheating flame F flows along the end face of the steel slab S, so the thermal influence on the side surface of the upper manifold 2 is small; (ii) in the near-end start method, the preheating flame F bounces off the upper surface of the steel slab S, heat A flows toward the outlet side of the steel slab S, and invades a gap G formed by the upper manifold 2, the left side nozzle unit 4 and the frame 5 (see FIG. 4), thereby causing the side portion of the upper manifold 2 to reach a high temperature.

[0020] In view of this, as shown in FIGS. 5(a) and 5(b), the inventors of the present invention installed a right-angled triangular heat shield plate 6 made of SS400 material with dimensions of 250 mm × 185 mm × 6 mm in the gap G formed by the upper manifold 2, the left side nozzle unit 4 and the frame 5. By installing the heat shield plate 6, the intrusion of heat derived from the preheating flame F is prevented, thereby reducing the heat load on the side portion of the upper manifold and reducing the gas leakage risk.

[0021] The upper nozzle unit 3 is a component that is frequently removed for inspection and maintenance, so the heat shield plate 6 is preferably installed at a position that does not interfere with the removal of the upper nozzle unit 3. Further, in the case where the lower end of the frame 5 is located below the upper surface of the upper nozzle unit 3, if the position of the heat shield plate 6 is too high, heat may be trapped between the heat shield plate 6 and the frame 5 and the left side nozzle unit 4. For this reason, the heat shield plate 6 is preferably arranged as low as possible so that heat derived from the preheating flame F flows to the back side of the frame 5. As one embodiment, as shown in FIG. 6, the heat shield plate 6 is preferably installed at a height 10 mm above the lower surface of the upper manifold 2. [Example]

[0022] Figure 8 shows the measured ambient temperature on the side of the upper manifold when one side of a steel billet is being cut with heat shield 6, before and after installation. In Figure 8, the horizontal axis represents elapsed time, and the vertical axis represents temperature. As shown in Figure 8, the ambient temperature, which rose to over 1100°C before the installation of heat shield 6, was reduced to below 500°C after the installation of heat shield 6. This confirmed that the heat load on the side of the upper manifold 2 was reduced, thereby reducing the risk of gas leakage.

[0023] Although embodiments applying the invention made by the present inventors have been described above, the present invention is not limited by the descriptions and drawings that constitute part of the disclosure of the present invention in this embodiment. That is, all other embodiments, examples, and operational techniques made by those skilled in the art based on this embodiment are included in the scope of the present invention. [Explanation of Symbols]

[0024] 1. Scarfer device 2 Upper manifold 3. Upper burner unit 4. Left side burner unit 5 frames 21a, 21b Flammable gas piping 22a, 22b Oxygen piping 23 Cooling pipe 24a~24d cap S billet

Claims

1. A scarfering device comprising: an upper manifold for supplying flammable gas, preheating oxygen, and cutting oxygen; a side nozzle unit positioned on the side of the upper manifold for cutting the surface of a steel slab being transported using the flammable gas, preheating oxygen, and cutting oxygen supplied from the upper manifold; and a plate-shaped frame for holding the upper manifold, positioned on the exit side in the steel slab transport direction of the upper manifold and the side nozzle unit. A scarfer device comprising a heat shield installed in the gap formed by the upper manifold, the side nozzle unit, and the frame, which prevents heat generated when the surface of the steel billet is melted from entering the side of the upper manifold.

2. The scarfer apparatus according to claim 1, wherein the side nozzle unit preheats the steel slab in a near-end start manner when cutting the surface of the steel slab.

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