JP5026222B2 - Surface layer melting apparatus for cast steel pieces and surface layer melting method - Google Patents

Description

  The present invention relates to a surface layer melting apparatus and a surface layer melting method for melting a surface layer of, for example, a continuous cast slab of steel or a steel slab during rolling.

  For example, as a treatment method for modifying a cast steel piece such as a cast piece after continuous casting or a steel piece in the middle of rolling, for example, the surface layer of the cast steel piece to be conveyed is melted by one or both of induction heating and plasma heating. A method for modifying the surface layer by adding a metal or an alloy to the molten surface layer portion has been proposed (Patent Document 1).

  By the way, in the melting treatment of the surface layer of such a cast steel piece, it is necessary to uniformly heat and melt the cast steel piece and to melt the surface layer of the cast steel piece as uniformly as possible. Therefore, for example, when melting the surface layer of a cast steel piece using plasma heating, the plasma arc is reciprocated in a direction orthogonal to the direction of conveyance of the cast steel piece using the electromagnetic force of an alternating magnetic field, so that the surface layer of the cast steel piece is A method of melting and performing surface treatment has been proposed (Patent Document 2).

  Further, in order to uniformly melt the surface layer of the cast steel piece, it is also important to uniformly add a metal or an alloy to the molten surface layer portion of the cast steel piece. As a method for adding this metal or alloy, Patent Document 1 discloses that the metal or alloy to be added is processed into a wire or sheet shape and added to a molten surface layer portion of a cast steel piece. As another method, a granular metal or alloy is placed on the surface of the cast steel piece before melting, or the granular metal or alloy is mixed with an appropriate gas or liquid, and before melting. A method of adding a metal or alloy to the surface layer of a cast steel piece by spraying the surface of the cast steel piece with a spray nozzle or the like has been proposed (Patent Document 3). In the present application, “cast steel slab” is a general term for “slab slab” and “steel slab”, “slab slab” is a steel material after casting, and “steel slab” is a slab rolled. It means later steel.

JP 2004-195512 A JP 54-142152 A JP 2006-124762 A

  However, when a metal or alloy is added to the melted surface layer portion of a cast steel piece using the method disclosed in Patent Document 1, it is very difficult to manufacture the alloy in advance or process it into a wire or sheet shape. Cost was high, and the material cost of the metal or alloy was high. Further, when a metal or alloy is added to the molten surface layer portion of the cast steel piece using the method disclosed in Patent Document 3, for example, when the metal is melted by induction heating, on the surface of the cast steel piece before melting. If the metal or alloy is ferromagnetic, the metal or alloy is attracted to the magnetic field generated during induction heating, so that the metal or alloy that can be added is limited to non-magnetic. In addition, for example, when a metal is melted by plasma heating, the metal or alloy on the surface of the cast steel piece before melting may be scattered by the plasma gas blown to the surface layer of the cast steel piece, and the supplied metal or alloy May not be used effectively.

  The present invention has been made in view of such a point, and an object thereof is to efficiently and uniformly add a metal or an alloy used for reforming the surface layer of a cast steel piece, and to uniformly perform the melting treatment of the surface layer of the cast steel piece. To do.

In order to achieve the above object, the present invention provides a surface layer melting apparatus for adding a metal or an alloy to a surface layer of a cast steel slab to be transported, and melting the surface layer by a plasma arc from a plasma torch. Behind the torch, in the conveying direction of the cast steel slab, a granular material supply device that supplies granular metal or alloy onto the surface of the cast steel slab before being melted by the plasma arc, and the granular material supplied by the granular material supply device And a reduction roll for pressing the metal or alloy into the surface layer of the cast steel piece.

  According to the present invention, a granular material supply device for supplying granular metal or an alloy on the surface of a cast steel piece before melting by a plasma arc is provided behind the plasma torch in the conveying direction of the cast steel piece, and the granular material supply device. Is provided with a rolling roll that press-fits the granular metal or alloy supplied to the surface of the cast steel slab before the surface of the cast steel slab is heated and melted by the plasma arc generated by the plasma torch. The metal or alloy used for the modification of the surface layer can be pressed into the surface layer of the cast steel piece. Thereby, even if the surface layer of the cast steel piece is melted by the plasma arc, the metal or alloy is not scattered by the plasma arc, and the metal or alloy supplied from the granular material supply device can be used effectively. Further, when the surface layer of the cast steel piece is melted by the plasma arc, the metal or alloy press-fitted into the surface layer of the cast steel piece is uniformly diffused into the surface layer. Therefore, the metal or alloy can be efficiently and uniformly added to the surface layer of the cast steel piece, and the surface layer of the cast steel piece can be uniformly melted.

  Before the surface layer of the cast steel piece is melted by the plasma arc, an electromagnetic induction coil for preheating the surface layer is further provided, and the granular material supply device and the reduction roll are located behind the electromagnetic induction coil in the conveying direction of the cast steel piece. It may be provided. Even when the surface layer of the cast steel piece is preheated by the electromagnetic induction coil in this way, the metal or alloy is pressed into the surface layer of the cast steel piece before the surface layer is preheated. However, the magnetic field generated by the electromagnetic induction coil is not attracted. Therefore, regardless of whether the metal or alloy is nonmagnetic or ferromagnetic, the metal or alloy can be efficiently added to the surface layer of the cast steel piece.

  The granular material supply device can accommodate the granular metal or alloy therein, and has a container in which an opening extending in a direction perpendicular to the conveying direction of the cast steel piece is formed on the front surface in the conveying direction of the cast steel piece. And the container may be capable of vibrating in the vertical direction.

  The granular material supply device can accommodate the granular metal or alloy therein, and has a container formed with an opening extending in a direction perpendicular to the conveying direction of the cast steel piece on the front side in the conveying direction of the cast steel piece. And a moving member that moves the granular metal or alloy in the container to the opening on the front surface.

  A plurality of the plasma torches are provided in parallel with a direction perpendicular to the direction of transport of the cast steel pieces, and the granular material supply device is provided between each of the plasma torches, and the direction of transport of the cast steel pieces than the reduction roll You may have the supply port provided behind and which supplies the said granular metal or alloy.

  According to another aspect of the present invention, there is provided a surface layer melting treatment method in which a surface layer of a cast steel piece to be conveyed is melt-treated by plasma, and a granular metal or alloy is supplied onto the surface of the cast steel piece before being melted by the plasma. A step of pressing a granular metal or alloy supplied onto the surface of the cast steel piece into a surface layer of the cast steel piece, and a cast steel piece into which the granular metal or alloy is pressed by heating using plasma. Melting the surface layer and modifying the surface layer.

  After the step of press-fitting the granular metal or alloy into the surface layer of the cast steel slab, and further before the step of melting the surface layer of the cast steel slab by the plasma, further comprising a step of performing induction preheating on the cast steel slab. You may do it.

  ADVANTAGE OF THE INVENTION According to this invention, a metal or an alloy can be efficiently and uniformly added to the surface layer of a cast steel piece, and the melting process of the surface layer of a cast steel piece can be performed uniformly.

  Hereinafter, preferred embodiments of the present invention will be described. FIG.1 and FIG.2 is a longitudinal cross-sectional view which shows the outline of a structure of the surface layer fusion processing apparatus 1 of the slab H concerning this Embodiment. The slab H is, for example, a continuous cast slab having a thickness of 250 mm and a width of 1200 mm, and is carbon steel containing 0.2% by mass of carbon. Further, in the melting treatment of the surface layer of the slab H of the present embodiment, the surface layer of the slab H is modified by adding ferronickel F containing nickel of 25% by mass as a granular metal or alloy. is doing. The granular metal or alloy to be added can be exemplified by a particle diameter of about 1 mm to 10 mm. In this embodiment, granular ferronickel F having a diameter of about 3 mm is used.

  The surface layer melting apparatus 1 is provided on a conveying line for the slab H that is conveyed in the horizontal direction. As shown in FIGS. 1 and 2, the surface layer melting apparatus 1 has a rectangular parallelepiped chamber 2, for example. A carry-in port 3 for carrying in the slab H is formed on the side surface of the chamber 2, and an open / close shutter 4 is provided in the carry-in port 3. On the side facing the carry-in port 3 of the chamber 2, a carry-out port 5 for carrying out the slab H is formed, and an open / close shutter 6 is provided at the carry-out port 5. In the chamber 2, a conveyance roller 7 for conveying the slab H is continuously provided from the outside of the chamber 2. During the melting process of the surface layer of the steel slab H, the atmosphere of the chamber 2 is maintained in an inert gas atmosphere, for example, an atmosphere of argon gas or a mixed gas of hydrogen and argon gas.

  A plasma torch 8 penetrating the upper surface of the chamber 2 is provided on the upper surface of the chamber 2. A plurality of, for example, twelve plasma torches 8 are arranged in parallel along the direction perpendicular to the conveying direction D of the slab H, for example, at intervals of 100 mm. The plasma torch 8 can form a plasma arc P by DC plasma with the slab H by applying a voltage from a DC power source (not shown). The plasma gas for generating the plasma arc P is preferably a non-oxidizing gas such as argon gas or a mixed gas of hydrogen and argon gas.

  An AC magnetic field is applied to the plasma arc P below the plasma torch 8 and forward and backward in the transport direction D of the slab H, that is, forward and backward in the transport direction D of the plasma arc P formed by the plasma torch 8. Electromagnetic coils 9 and 10 are provided in parallel to face each other. The electromagnetic coils 9 and 10 have, for example, a loop shape and extend in a direction perpendicular to the conveyance direction D of the slab H. These electromagnetic coils 9 and 10 generate an alternating magnetic field between the electromagnetic coils 9 and 10 by supplying an alternating current from an alternating current power source (not shown), and periodically apply an electromagnetic force to the plasma arc P. . Thereby, the plasma arc P can be reciprocated in a direction perpendicular to the conveying direction D of the slab H according to the supplied AC frequency.

  Inside the chamber 2 and behind the plasma torch 8 in the conveying direction D of the slab H, that is, behind the plasma arc P in the conveying direction D of the slab H, on the surface of the slab H before melting. A granular material supply device 20 for supplying granular ferronickel F is provided. The granule supply device 20 is provided above the slab H. As shown in FIGS. 3 and 4, the granule supply device 20 can accommodate ferronickel F, a tray 21 for supplying ferronickel F onto the surface of the slab H, and ferronickel F on the tray 21. And a shooter 22 for supplying. The tray 21 has a rectangular parallelepiped shape whose width is slightly smaller than the width of the slab H (the direction perpendicular to the conveyance direction D of the slab H), and the upper surface 21a is open. Further, the front surface 21b on the front side in the transport direction D of the slab H of the tray 21 is opened, and constitutes an opening for supplying ferronickel F onto the surface of the slab H. The tray 21 can vibrate in the vertical direction by a vibration mechanism (not shown). The shooter 22 is installed above the tray 21. In the granular material supply device 20, ferronickel F is supplied from the shooter 22 to the tray 21, and the tray 21 vibrates in the vertical direction, so that the ferronickel F is transferred from the front surface 21 b of the tray 21 onto the surface of the slab H. Supplied.

  As shown in FIGS. 1 to 4, ferronickel F supplied by the particle supply device 20 is pressed into the surface layer of the slab H between the particle supply device 20 and the plasma arc P (plasma torch 8). A reduction roll 23 is provided. The reduction roll 23 is provided in contact with the surface of the slab H. The reduction roll 23 extends in a direction perpendicular to the conveying direction D of the slab H, and its length is slightly shorter than the width of the slab H (the direction perpendicular to the conveying direction D of the slab H). The rolling roll 23 is loaded with a downward force of 30 to 100 tons in order to press-fit ferronickel F into the surface layer of the slab H, and the rolling roll 23 is formed of the slab H by a motor (not shown), for example. It is rotatable in the transport direction D. A support roll 24 for supporting a downward force applied to the reduction roll 23 is provided at a position facing the reduction roll 23 with the slab H interposed therebetween.

  The surface layer melting apparatus 1 according to the present embodiment is configured as described above. Next, the melting process of the slab H performed in the surface layer melting apparatus 1 will be described. In the present embodiment, the melting process is performed on the surface layer whose depth from the upper surface of the slab H is, for example, up to 5 mm.

  First, the opening / closing shutter 4 of the carry-in port 3 is opened, and the slab H is carried into the chamber 2 at a transfer speed of 5 mm / second, for example. When the slab H is conveyed to below the granular material supply device 20, the tray 21 of the granular material supply device 20 is vibrated in the vertical direction to continuously supply ferronickel F to the surface of the slab H. At this time, the ferronickel F in the tray 21 is uniformly diffused in the direction perpendicular to the conveying direction D of the slab H by the vibration of the tray 21. Then, the ferronickel F supplied to the surface of the slab H is uniformly diffused in the direction perpendicular to the conveyance direction D of the slab H.

  The slab H supplied with ferronickel F on the surface is conveyed to the lower side of the reduction roll 23. Then, when the slab H passes below the reduction roll 23, the surface of the slab H is reduced by the reduction roll 23 with a force of, for example, 30 tons. By this reduction, ferronickel F on the surface of the slab H is pushed into the surface layer of the slab H. At this time, since the reduction roll 23 rotates in the conveyance direction D of the slab H, the conveyance of the slab H is not hindered by the reduction roll 23.

  The slab H in which ferronickel F is press-fitted into the surface layer is conveyed to the lower side of the plasma torch 8. Then, a voltage is applied to the plasma torch 8 from a DC power source, and a plasma arc P by DC plasma is formed between the plasma torch 8 and the slab H. At the same time, an alternating current is supplied to the electromagnetic coils 9 and 10 from an alternating current power source, and the plasma arc P is reciprocated in a direction perpendicular to the conveying direction D of the slab H by the electromagnetic force generated by the alternating magnetic field.

  When the plasma arc P is formed on the surface of the slab H, the surface layer of the slab H is melted by the heat of the plasma arc P, and the plasma melting part 30 is formed on the surface layer of the slab H. In the plasma melting portion 30, ferronickel F is also melted, and ferronickel F is uniformly diffused in the surface layer of the slab H. Thereafter, the slab H is unloaded from the carry-out port 5 and is cooled by, for example, a cooling device (not shown) outside the chamber 2, and the surface layer of the slab H is solidified. Then, a series of melting processes for modifying the surface layer of the slab H is completed.

  According to the above embodiment, before the surface layer of the slab H is melted by the heat of the plasma arc P, the ferronickel F is supplied onto the surface of the slab H by the granular material supply device 20, and on the surface. Since the supplied ferronickel F is pressed into the surface layer of the slab H by the rolling roll 23, even when the surface layer of the slab H is melted by the plasma arc P, the ferronickel F is formed by the plasma arc P of the slab H. It does not scatter from the surface layer. Thereby, the ferronickel F supplied from the granular material supply apparatus 20 can be used effectively. Since the tray 21 vibrates in the vertical direction, the ferronickel F is supplied onto the surface of the slab H from the granular material supply device 20, so that the ferronickel F in the tray 21 is cast into the slab by this vibration. H can be uniformly diffused in a direction perpendicular to the conveyance direction D, and as a result, ferronickel F can be uniformly diffused on the surface of the slab H. Furthermore, when the surface layer of the slab H is melted by the plasma arc P, the ferronickel F press-fitted into the surface layer of the slab H is uniformly diffused into the surface layer. Therefore, ferronickel F can be efficiently and uniformly added to the surface layer of the slab H, and the surface layer of the slab H can be uniformly melted.

  In the present embodiment, only ferronickel F is added to modify the surface layer of the slab H, but the present invention is also effective when, for example, different types of metals or alloys are added. . That is, when a different kind of metal or alloy is supplied from the shooter 22 to the tray 21, the tray 21 vibrates in the vertical direction, so that the supplied metal or alloy is uniformly diffused in the tray 21, and the surface layer of the slab H The desired alloy diffuses uniformly. Therefore, it is not necessary to manufacture the alloy in advance as in the prior art, and the material cost of the alloy added to the surface layer of the slab H can be suppressed. In addition, as a different kind of metal or alloy, ferrosulfur, ferrochrome, ferrotitanium, ferrosilicon, vanadium, chromium, titanium, nickel, carbon saturated iron, cast iron, etc. can be used, for example.

  In the surface layer melting treatment apparatus 1 of the above embodiment, as shown in FIG. 5, before the surface layer of the slab H is melted, electromagnetic induction coils 40 and 41 for preheating the surface layer are further provided. Also good. The electromagnetic induction coils 40 and 41 are located behind the plasma torch 8 in the conveying direction D of the slab H, that is, behind the conveying direction D of the plasma arc P formed by the plasma torch 8 and cast more than the rolling roll 23. Opposite and parallel to each other in front of the conveying direction D of the piece H. The electromagnetic induction coils 40 and 41 extend in a direction perpendicular to the conveyance direction D of the slab H. In this case, after the ferronickel F is press-fitted into the surface layer of the slab H by the reduction roll 23, the surface layer of the slab H is preheated by the electromagnetic induction coils 40 and 41. Thereafter, the surface layer of the slab H is melted by the plasma arc P, and the ferronickel F can be uniformly diffused into the surface layer of the slab H. Since the ferronickel F is press-fitted into the surface layer of the slab H before the surface layer of the slab H is preheated in this way, the magnetic field generated by the electromagnetic induction coils 40 and 41 even with a ferromagnetic alloy such as ferronickel F. Will not be attracted to. Therefore, the ferronickel F supplied on the surface of the slab H can be used effectively. Further, by preheating the surface layer of the slab H in advance, the subsequent surface layer can be efficiently melted.

  The granule supply device 20 of the above embodiment is provided with the tray 21 that can vibrate in the vertical direction. However, as shown in FIGS. A moving member 50 that can move in the horizontal direction may be provided. The moving member 50 extends in a direction perpendicular to the conveyance direction D of the slab H, and its length is slightly shorter than the width of the tray 21 (the direction perpendicular to the conveyance direction D of the slab H). In such a case, the ferronickel F supplied into the tray 21 from the shooter 22 is intermittently supplied onto the surface of the slab H from the front surface 21 b opened in the tray 21 by the movement of the moving member 50. Thus, while the moving member 50 is moving in the tray 21, the ferronickel F can be uniformly diffused in the direction perpendicular to the conveying direction D of the slab H. As a result, the ferronickel F is cast into the slab. It can be uniformly diffused on the surface of H.

  Although the tray 21 and the chute 22 were provided in the granular material supply apparatus 20 of the above embodiment, the supply port 60 which supplies ferronickel F on the surface of the slab H as shown in FIG. A plurality of nozzles 61 may be provided. The nozzle 61 extends in a direction perpendicular to the conveyance direction D of the slab H, and is provided behind the reduction roll 23 in the conveyance direction D of the slab H. A plurality of supply ports 60 are arranged so as to be positioned between the plasma torches 8 when viewed from the conveyance direction D of the slab H. In such a case, ferronickel F is supplied onto the surface of the slab H between the plasma torch 8 from the supply port 60. Then, the ferronickel F on the surface of the slab H is pressed into the surface layer of the slab H by the reduction roll 23 and then melted in the plasma melting portion 30 generated by the plasma arc P. At this time, a surface tension induced flow 62 of the molten slab H is generated in the plasma melting portion 30 by the plasma arc P. By this surface tension induced flow 62, the molten ferronickel F can be uniformly diffused in the surface layer of the slab H.

  INDUSTRIAL APPLICABILITY The present invention is useful, for example, for a surface layer melting apparatus and a surface layer melting method for melting a surface layer of a continuous cast slab of steel or a steel slab during rolling.

It is a longitudinal cross-sectional view which shows the outline of a structure of the surface layer fusion processing apparatus concerning this Embodiment. It is a top view which shows the outline of a structure of the surface layer fusion processing apparatus concerning this Embodiment. It is a longitudinal cross-sectional view which shows the outline of a structure of a granule supply apparatus. It is a top view which shows the outline of a structure of a granule supply apparatus. It is a longitudinal cross-sectional view which shows the outline of a structure of the surface layer melt processing apparatus concerning another form. It is a longitudinal cross-sectional view which shows the outline of a structure of a granule supply apparatus. It is a top view which shows the outline of a structure of a granule supply apparatus. It is a top view which shows the outline of a structure of a granule supply apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Surface melting processing apparatus 2 Chamber 3 Carrying-in port 4, 6 Opening / closing shutter 5 Carrying-out exit 7 Carrying roller 8 Plasma torch 9, 10 Electromagnetic coil 20 Granule supply apparatus 21 Tray 21a Upper surface 21b Front surface 22 Shutter 23 Roll under pressure 24 Support roll 30 Plasma Melting part 40, 41 Electromagnetic induction coil 50 Moving member 60 Supply port 61 Nozzle 62 Surface tension induced flow D Transport direction F Ferronickel H Cast slab P Plasma arc

Claims (7)

A surface layer melting apparatus for adding a metal or alloy to the surface layer of a cast steel piece to be conveyed, and melting the surface layer by a plasma arc from a plasma torch,
Behind the plasma torch, in the rear of the cast steel piece in the conveying direction,
A granular material supply device for supplying granular metal or alloy onto the surface of the cast steel piece before being melted by the plasma arc;
An apparatus for melting a surface layer of a cast steel piece, comprising: a reduction roll for pressing the granular metal or alloy supplied by the granular material supply device into the surface layer of the cast steel piece. Before melting the surface layer of the cast steel piece by the plasma arc, further comprising an electromagnetic induction coil for preheating the surface layer,
2. The apparatus for melting a surface layer of a cast steel piece according to claim 1, wherein the granular material supply device and the reduction roll are provided behind the electromagnetic induction coil in a direction in which the cast steel piece is conveyed. The granule supply device includes:
The container can accommodate the granular metal or alloy inside, and has a container in which an opening extending in a direction perpendicular to the conveying direction of the cast steel piece is formed on the front side in the conveying direction of the cast steel piece,
The apparatus for melting a surface layer of a cast steel piece according to claim 1 or 2, wherein the container is capable of vibrating in the vertical direction . The granule supply device includes:
A container in which the granular metal or alloy can be accommodated inside, and an opening extending in a direction perpendicular to the transport direction of the cast steel piece is formed on the front surface in the transport direction of the cast steel piece; and
The apparatus for melting a surface layer of a cast steel piece according to claim 1 or 2, further comprising a moving member that moves the granular metal or alloy in the container to the opening on the front surface. A plurality of the plasma torches are provided in parallel in a direction perpendicular to the conveying direction of the cast steel pieces,
The granule supply device has a supply port for supplying the granular metal or alloy provided between the plasma torches and provided behind the rolling roll in the transport direction of the cast steel piece. The apparatus for melting a surface layer of a cast steel piece according to claim 1 or 2, characterized by the above. A surface layer melting method for melting a surface layer of a cast steel piece to be conveyed by plasma,
Supplying a granular metal or alloy on the surface of the cast steel piece before being melted by the plasma;
Pressing the granular metal or alloy supplied on the surface of the cast steel piece into the surface layer of the cast steel piece; and
A method of melting the surface layer of the cast steel piece into which the granular metal or alloy is press-fitted by heating using plasma, and modifying the surface layer. After the step of press-fitting the granular metal or alloy into the surface layer of the cast steel piece, before the step of melting the surface layer of the cast steel piece by the plasma,
The method for surface layer melting treatment of a cast steel piece according to claim 6, further comprising a step of performing induction preheating on the cast steel piece.

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