JP6565421B2 - Electric furnace - Google Patents

Description

  The present invention relates to an electric furnace, and more particularly to an electric furnace that melts a metal while moving the furnace body.

  In an electric arc furnace that is a kind of electric furnace that melts metal material, in the space inside the furnace body in which the metal material is accommodated, the distance from the electrode is short, and the hot spot where the metal material is likely to melt, A cold spot is formed which is far from the metal material and hardly melts the metal material. In the cold spot, in order to solve the problem that it takes time to heat the metal material and the melting of the entire metal material proceeds non-uniformly, in Patent Document 1, the furnace body is positioned around the vertical axis with respect to the electrode. It has been proposed to switch between a cold spot and a hot spot by rotationally displacing them. In such an electric furnace, without using electric power for a pump for an extra water cooling section like a shaft furnace, and without supplying burner combustion energy etc. for exhaust gas composition optimization processing, By performing rotational displacement of the body, it is possible to eliminate thermal non-uniformity in the furnace and reduce the use of wasted power.

JP 2014-40965 A

  In the arc furnace, a large current flows through an electrode inserted in the furnace body in order to melt the metal material. Due to the current flowing through this electrode, a current may also flow through the furnace body. In particular, when the current flowing through the electrode is an alternating current, an induced current constantly flows on the surface of the furnace body. In order to rotationally displace the furnace body, a furnace body motion mechanism having a moving part such as a bearing is used, but this kind of leakage current flowing through the metal material in the furnace and induced current flowing on the surface of the furnace body. If it flows to the movable part, it may cause damage to the movable part and impair the function of the movable part. For example, in a state where the electrode is inserted into the furnace and energized, a leakage current flowing through the metal material in the furnace and an induced current generated in the furnace body flow to a member such as a bearing of the furnace body movement mechanism, When the spark is generated, even if the furnace body motion mechanism is stationary, the structural members of the furnace body motion mechanism may be damaged, and the subsequent smooth motion of the furnace body may be hindered.

  The problem to be solved by the present invention is to provide an electric furnace capable of preventing an electric current from flowing through a furnace motion mechanism that moves the furnace body in an electric furnace in which the furnace body is moved.

  In order to solve the above problems, an electric furnace according to the present invention includes a furnace body that contains a metal material, an electrode that melts the metal contained in the furnace body when energized, and the furnace body moves on an installation surface. The gist is to include a furnace motion mechanism that supports the furnace body and an insulating member that electrically insulates the furnace body and the furnace motion mechanism.

  Here, the furnace body movement mechanism has a first part fixed to the installation surface and a second part fixed to the furnace body and moving with respect to the first part. And it is preferable that the first part and the second part are electrically connected.

  In this case, the connecting wire that electrically connects the first part and the second part of the furnace motion mechanism has a length that can follow the entire range of motion of the second part. It is good to be.

  Further, it is preferable that the furnace body and the furnace body movement mechanism are independently grounded.

  The electric furnace includes a furnace cover that covers an opening of the furnace body, a furnace cover motion mechanism that moves the furnace cover relative to the furnace body, and electrically connects the furnace cover motion mechanism and the furnace body. It is preferable to further include an insulating member that electrically insulates. In this case, the furnace cover movement mechanism may be grounded independently of the furnace body.

  In the electric furnace according to the above invention, an insulating member is provided between the furnace body and the furnace motion mechanism. This prevents the current from flowing from the furnace body to the furnace motion mechanism even when the current flows through the furnace body due to the current flowing through the electrodes. As a result, in the furnace motion mechanism, damage due to current is prevented from occurring.

  Here, the furnace body movement mechanism has a first part fixed to the installation surface and a second part fixed to the furnace body and moving relative to the first part, When the part and the second part are electrically connected, the first part and the second part are equipotential. Therefore, even if a current flows through the furnace motion mechanism due to a dielectric breakdown of an insulating member that insulates the furnace body from the furnace motion mechanism, the current flows over a wide area inside the furnace motion mechanism. Flowing situations are less likely to occur. Thereby, it is possible to prevent the occurrence of serious damage to the furnace body motion mechanism with high accuracy.

  In this case, if the connecting wire that electrically connects the first part and the second part of the furnace body motion mechanism has a length that can follow the entire range of motion of the second part, When the second part is moved with respect to the first part, it is possible to prevent the connecting wire from being damaged or being subjected to excessive force.

  Further, when the furnace body and the furnace body motion mechanism are independently grounded, it is possible to more firmly prevent the current flowing through the furnace body from flowing into the furnace body motion mechanism.

  The electric furnace includes a furnace cover that covers the opening of the furnace body, a furnace cover motion mechanism that moves the furnace cover relative to the furnace body, and an insulation that electrically insulates the furnace cover motion mechanism and the furnace body. In the case of further having a member, it is possible to prevent the current flowing through the furnace body from flowing into the furnace cover movement mechanism. Thereby, also in the member which comprises a furnace cover part movement mechanism, it can prevent that the damage resulting from an electric current arises.

  In this case, when the furnace cover motion mechanism is grounded independently of the furnace body, the current flowing through the furnace body is more securely prevented from flowing to the furnace cover motion mechanism. can do.

It is a side view which shows the electric furnace concerning one Embodiment of this invention. It is a perspective view which shows a furnace body movement mechanism and a furnace body part insulation member. The furnace body insulating member is shown with a broken line in perspective. It is an expanded sectional view of a furnace body motion mechanism. It is a figure which shows the specific example of the installation method of a bearing part connection line, (a) shows the state seen from the upper direction of a furnace body movement mechanism, (b) has shown the AA cross section of (a). In (a), the broken line has shown the state of the bearing part connection line at the time of turning a furnace body 50 degrees.

  Hereinafter, an electric furnace according to an embodiment of the present invention will be described with reference to the drawings.

[Configuration of electric furnace]
1-4 show an electric furnace 1 according to an embodiment of the present invention. The electric furnace 1 is installed on a platform 90, and has an electric furnace (arc furnace) similar to that described in Patent Document 1 as a main body, and includes a furnace body 10, a furnace lid 20, and an electrode 25. It has. In addition to these, the electric furnace 1 includes a furnace body movement mechanism 30 and further includes a furnace lid holding device 40 including a furnace lid movement mechanism 43. In addition, the electric furnace 1 is provided with a furnace body insulating member 51 and a furnace lid insulating member 52 as insulating members, as well as a furnace ground wire 61, a furnace motion mechanism ground wire 62, and a furnace lid motion. A mechanism ground wire 63 is provided.

  The furnace body 10 is formed as a bottomed substantially cylindrical container having an opening on the upper side. The furnace body 10 is made of a material in which an iron skin is provided outside a refractory made of a metal oxide.

  The furnace lid 20 is a member formed in a substantially disc shape and capable of closing the opening of the furnace body 10. The furnace lid 20 is held by the furnace lid holding device 40 and moves between a state in which the opening of the furnace body 10 is closed and a state in which the opening is closed by performing a vertical motion and a turning motion above the furnace body 10. can do. The furnace lid 20 is also made of the same material as that of the furnace body 10, but an insulator is exposed in the vicinity of a portion through which the electrode 25 described below passes, and electrical insulation is provided between the furnace lid 20 and the electrode 25. I keep it.

  Three electrodes 25 penetrate the furnace lid 20 from above toward the space inside the furnace body 10 (only two are shown in FIG. 1). The three electrodes 25 are arranged around the central axis of the furnace body 10 so as to form a substantially equilateral triangle. By storing a metal material such as iron scrap material in the furnace body 10 and applying a current such as a three-phase alternating current to the electrode 25 to perform discharge, the metal material can be melted. The electrode 25 is electrically insulated from the furnace body 10 and the furnace lid 20.

  The furnace body 10 is supported on a platform (installation surface) 90 via a furnace body motion mechanism 30. As shown in FIG. 2, the furnace body motion mechanism 30 has a substantially annular surface on the top and bottom, and has a support frame 31 made of metal. The furnace body 10 is placed with the furnace body insulating member 51 interposed therebetween. A plurality of recesses 31c are provided on the upper surface 31a of the support frame 31, and the furnace body 10 is caused by the weight of the furnace body 10 and the engagement of the projections (not shown) formed in the furnace body 10 with the recesses 31c. It is fixed on the support frame 31. The furnace body 10 and the support frame 31 are electrically insulated by a furnace body insulating member 51. A gear body 31 b is formed on the inner peripheral surface of the support frame 31. A portion between the bottom of the furnace body 10 and the support frame 31 is filled with an insulating resin so that the furnace body insulating member 51 is embedded, and the bottom of the furnace body 10, the furnace body insulating member 51, and the support frame. A gap formed between the layers 31 is filled with an insulating resin.

  The support frame 31 is supported by bearings 32. A sectional view of the vicinity of the bearing 32 is shown in FIG. The bearing 32 is attached to a metal mounting base 34 fixed on the platform 90. The bearing 32 has a configuration of a known slewing bearing. Each of the bearings 32 is a metal outer ring (first part) 32a and inner ring (second part) 32b, and is disposed between the outer ring 32a and the inner ring 32b. It has a moving body (not shown), and the inner ring 32b can smoothly turn with respect to the outer ring 32a. Here, the outer ring 32 a is fixed to the mounting base 34, and the inner ring 32 b is fixed to the gear body 31 b of the support frame 31. The support frame 31 and the mounting base 34 are electrically connected by a bearing connection line 33. The bearing portion connection line 33 has a length that can follow the entire range of rotation of the support frame 31. Since the outer ring 32 a of the bearing 32 is in contact with the mounting base 34 and the inner ring 32 b is in contact with the support frame 31, the outer ring 32 a and the inner ring 32 b are electrically connected by the bearing portion connection line 33. ing.

  On the inner side of the support frame 31, a gear portion 35 including two gears 35a and 35b meshing with each other is provided. In FIG. 2, only one gear portion 35 is visible, but actually, another similar gear portion 35 is provided at an opposing position. The first gear 35 a constituting the gear portion 35 meshes with a gear body 31 b provided on the inner peripheral surface of the support frame 31. An output shaft of a hydraulic motor (not shown) is coupled to the rotation shaft of the second gear 35b meshed with the first gear 35a.

  The support frame 31 can be swung on the bearing 32 by driving the hydraulic motor of the gear portion 35. Thereby, the furnace body 10 is rotated (turned) on the platform 90. When the furnace body 10 is rotated, the position of the electrode 25 along the surface of the platform 90 is not changed. Therefore, the relative arrangement of the furnace body 10 and the electrode 25 is changed as the furnace body 10 rotates. A stopper mechanism (not shown) that holds the support frame 31 in a stopped state may be appropriately provided inside the support frame 31.

  The furnace lid holding device 40 is provided on a common platform 90 where the furnace body 10 is installed via the furnace body motion mechanism 30. The furnace cover holding device 40 supports the furnace cover 20 by the furnace cover support part 41 and moves the furnace cover 20 up and down and swivels. The furnace lid holding device 40 also has a function of holding the electrode 25 by the electrode support 42 and moving it up and down, and the vertical position of the electrode 25 according to the molten state of the metal material in the furnace body 10 and the like. Can be adjusted. The vertical movement and turning movement of the furnace lid 20 and the vertical movement of the electrode 25 are driven by a furnace lid movement mechanism 43 including a bearing and a hydraulic cylinder. The furnace lid support part 41 and the electrode support part 42 are electrically insulated. Further, a furnace cover part insulating member 52 is provided between the furnace cover support part 41 and the furnace cover part movement mechanism 43, and the space between the furnace cover 20 and the furnace cover support part 41 and the furnace cover part movement mechanism 43 is provided. It is electrically insulated. In addition, a portion on the furnace cover motion mechanism 43 side partitioned by the furnace cover insulating member 52 is grounded by a furnace cover motion mechanism ground wire 63.

  The platform 90 on which the electric furnace 1 is installed is a gantry made of metal. The platform 90 is grounded by a furnace body motion mechanism ground wire 62. Since the mounting base 34 of the furnace body motion mechanism 30 is in contact with and fixed on the platform 90, the bearing 32 of the furnace body motion mechanism 30 is grounded at the outer ring 32a by the furnace body motion mechanism ground wire 62. Connected. The platform 90 may be provided with a tilting mechanism for tilting the constituent members of the electric furnace 1 including the furnace body 10, thereby facilitating steeling and tapping from the furnace body 10.

  In this electric furnace 1, there are provided three ground wires, namely, a furnace ground wire 61, a furnace motion mechanism ground wire 62, and a furnace cover motion mechanism ground wire 63. These are provided as independent ground wires. It has been. For example, three ground wires 61 to 63 are respectively connected to three ground poles embedded in the ground at remote positions.

[Characteristics of electric furnace]
As described above, in the electric furnace 1 according to the present embodiment, the furnace body moving mechanism 30 rotates the furnace body 10 with respect to the electrode 25 to change the positional relationship between the furnace body 10 and the electrode 25. it can. Thereby, the uniformity of heating and melting of the metal material in the furnace body 10 can be enhanced. In other words, the electrode 25 is arranged in a triangle around the central axis of the substantially cylindrical furnace body 10, so that a hot spot that is close to the electrode 25 and easily becomes high temperature, and is far from the electrode 25 and becomes high temperature. Difficult cold spots are inevitably generated in the furnace body 10, but the hot spot and the cold spot are changed by rotating the furnace body 10 during the melting process of the metal material and changing the positional relationship with the electrode 25. It can be replaced as appropriate to achieve uniform heating and melting. From the viewpoint of changing the positions of the hot spot and the cold spot as necessary and sufficient, the angular range in which the furnace body 10 can be rotated is preferably about 50 ° to 60 °.

  When performing arc discharge, an alternating current of the order of several tens of kA is passed through the electrode 25 inserted into the furnace body. This current flows through the metal material in the furnace body 10, the furnace body 10, the furnace lid 20, and the like to the furnace body motion mechanism 30 and the furnace lid motion mechanism 43, and may cause a leakage current. In addition, an induced current of several A to several hundred A may flow through the iron skin on the surface of the furnace body 10. When such a leakage current or induction current flows from the furnace body 10 to a movable part such as a bearing of the furnace body motion mechanism 30 or the furnace cover motion mechanism 43, the furnace body motion mechanism 30 or the furnace cover motion mechanism 43 is stationary. Even if it is in such a state, sparks may occur in the movable part, preventing smooth movement in the movable part, and possibly irreversible damage such as loss of material constituting the movable part. There is.

  However, in the electric furnace 1 according to the present embodiment, the furnace body insulating member 51 is provided between the furnace body 10 and the furnace body motion mechanism 30, and the space between the furnace body 10 and the furnace body motion mechanism 30 is electrically connected. Insulated. In the furnace lid holding device 40, a furnace lid insulating member 52 is provided between the furnace lid support 41 and the furnace lid motion mechanism 43, and the furnace lid 20 and the furnace lid 20 are closed. The furnace body 10 that is in contact with the lid 20 on the iron skin and the furnace lid movement mechanism 43 are electrically insulated. As a result, even if an induced current or leakage current flows through the furnace body 10, these currents are prevented from flowing into the furnace body motion mechanism 30 or the furnace lid motion mechanism 43. Examples of the insulating material constituting the furnace body insulating member 51 and the furnace lid insulating member 52 are JIS-H type insulators having high heat resistance, such as a laminate made of silicone resin and glass (silicone laminate material). can do.

  Further, in the electric furnace 1, each part is independently grounded. That is, the furnace body 10 is grounded by the furnace body ground wire 61, the furnace body motion mechanism 30 is grounded by the furnace body motion mechanism ground wire 62 via the platform 90, and the furnace lid motion mechanism 43 is moved by the furnace lid motion. The mechanism ground wire 63 is grounded. As a result, even if the furnace body insulating member 51 and the furnace lid insulating member 52 cause dielectric breakdown due to factors such as the application of a high voltage on both sides, the induced current flowing in the furnace body 10 The leakage current flows through the furnace ground wire 61 to the ground potential, and does not easily flow into the furnace motion mechanism 30 or the furnace lid motion mechanism 43.

  In the electric furnace 1, in the bearing 32 of the furnace body motion mechanism 30, the outer ring 32 a and the inner ring 32 b are electrically connected by the bearing connection line 33. Thereby, the outer ring 32a and the inner ring 32b are maintained at the same potential. Furthermore, not only the outer ring 32a that is grounded by the furnace body motion mechanism grounding wire 62 via the platform 90 and the mounting base 34, but also the inner ring 32b is grounded. As a result, a current is prevented from flowing through between the outer ring 32a and the inner ring 32b. Therefore, even if an induced current or a leakage current flowing through the furnace body 10 flows to either the outer ring 32a or the inner ring 32b, the current flows to the other and sparks in a wide area of the bearing 32. Is prevented from occurring.

  In FIG. 3, the bearing portion connection line 33 is simplified as wiring for connecting the support frame 31 and the mounting base 34, but if the outer ring 32 a and the inner ring 32 b of the bearing 32 can be electrically connected, The specific installation method of the part connection line 33 may be any method. An example of the attachment method is shown in FIG. Here, a bracket 31 c that is electrically connected to the main body of the support frame 31 is provided near the center of the support frame 31 in the height direction. A connecting rod 91 that is electrically connected to the platform 90 main body is erected on the platform 90, and a bracket 91a is provided at the upper end of the connecting rod 91 so as to be substantially the same height as the frame side bracket 31c. The connecting rod 91 is provided at an approximately angular position in the movable range of the inner ring 32 b of the bearing 32. One end of the bearing portion connection line 33 is connected to the support frame side bracket 31c, and the other end is connected to the connection rod side bracket 91a. The bearing connecting line 33 has a length that can follow the entire movable range of the inner ring 32 b of the bearing 32. Further, in the entire movable range of the inner ring 32b, the bearing connecting line 33 is located above obstacles (not shown) such as necessary devices attached to the driving device provided on the platform 90 for driving the bearing 32. As described above, the positions of the two brackets 31c and 91a and the length of the bearing connecting line 33 are set.

  Thus, by connecting the bearing portion connection line 33 using the brackets 31c and 91a, the conduction between the outer ring 32a and the inner ring 32b of the bearing 32 can be ensured with high reliability. Then, by setting the bearing portion connection line 33 to a length that can follow the entire range of the turning motion of the inner ring 32b, the entire range of the turning motion of the inner ring 32b as shown by a solid line and a broken line in FIG. Further, it is possible to prevent the bearing portion connecting wire 33 from being damaged or applying an excessive external force. In particular, as shown in FIG. 4B, the bearing portion connection line 33 is arranged so that the bearing portion connection line 33 can be maintained in a bent state without being strained over the entire range of the turning motion of the inner ring 32b. If the length is set longer, damage to the bearing portion connecting wire 33 and application of external force can be effectively prevented.

  Further, the bearing connecting line 33 is positioned above the surface of the platform 90, and further from obstacles (not shown) such as necessary devices attached to the driving device provided on the platform 90 for driving the bearing 32. Further, by arranging at the upper position, when the inner ring 32b of the bearing 32 turns, it can be avoided that the bearing connecting line 33 interferes with the obstacle. When a member that can be an obstacle to the bearing connection line 33 is provided in a region on the platform 90 through which the bearing connection line 33 passes along with the turning movement of the inner ring 32b, the bearing connection line 33 is Rather than routing along the platform 90, routing at least a position above the surface of the platform 90 and further above the obstacle, the obstacle and the bearing portion connection line 33 Interference between can be avoided. As described above, it is preferable that the bearing connecting line 33 has a length that can maintain the bent state. However, the bearing portion connecting line 33 has such a length that the bent portion does not hit the obstacle as described above. It is better to keep it. As described above, if the connecting rod 91 is provided at an angular position corresponding to the center of the movable range of the inner ring 32b, the bearing portion connection line 33 is not excessively lengthened, and the bearing is extended over the entire movable range of the inner ring 32b. It is easy to ensure bending in the part connection line 33.

  As mentioned above, although embodiment of this invention was described in detail, this invention is not limited to the said embodiment, A various change is possible in the range which does not deviate from the summary of this invention. For example, the motion of the furnace body is not limited to rotation (turning) around the center of the furnace body, and any motion on the platform can be employed. Further, the furnace motion mechanism is not limited to the one using the bearing, and other examples using the roller can be exemplified.

DESCRIPTION OF SYMBOLS 1 Electric furnace 10 Furnace 20 Furnace 25 Electrode 30 Furnace motion mechanism 31 Support frame 31c Bracket 32 Bearing 32a Outer ring 32b Inner ring 33 Bearing part connection line 34 Mounting base 35 Gear part 40 Furnace part holding device 41 Furnace cover support part 42 Electrode support portion 43 Furnace portion motion mechanism 51 Furnace portion insulating member 52 Furnace portion insulating member 61 Furnace ground wire 62 Furnace motion mechanism ground wire 63 Furnace motion mechanism ground wire 90 Platform (installation surface)
91 Connecting rod 91a Bracket

Claims (4)

A furnace body containing a metal material;
An electrode for melting the metal contained in the furnace body by energization;
A furnace body motion mechanism for supporting the furnace body movably on an installation surface;
An insulating member that electrically insulates the furnace body and the furnace motion mechanism ,
The furnace body movement mechanism has a first part fixed to the installation surface, and a second part fixed to the furnace body and moving with respect to the first part,
The first part and the second part are electrically connected,
The connecting wire that electrically connects the first part and the second part of the furnace body motion mechanism has a length that can follow the entire range of motion of the second part. Electric furnace. The electric furnace according to claim 1, wherein the furnace body and the furnace motion mechanism are independently grounded. The electric furnace includes a furnace lid that covers an opening of the furnace body;
A furnace lid movement mechanism for moving the furnace lid relative to the furnace body;
Electric furnace according to claim 1 or 2, further comprising a electrically insulating insulating member said furnace body and the furnace lid motion mechanism. The electric furnace according to claim 3 , wherein the furnace cover movement mechanism is grounded independently of the furnace body.

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