JPS6322885B2 - - Google Patents

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to an electrical heating method for rolled material, and is particularly suitable for heating a sheet bar at the entry side of a finishing mill, between rolling mills or between unwinding and rolling of a rolled sheet bar. The present invention relates to an improvement in a method for heating a rolled material by applying current to the rolled material using an electrode to heat the rolled material.

[Conventional technology]

In hot rolling of sheet bars, the sheet bars are heated on the entry side of the finishing mill in order to improve the rollability and bondability of the sheet bars. For example, as an example of hot joining sheet bars to each other for continuous rolling, there is a completely continuous rolling arrangement row by joining sheet bars, which the applicant has already proposed in JP-A-58-112601, and JP-A-Sho. There is a continuous rolling hot rolling line proposed in 58-209405. That is, the rolling arrangement proposed in the above-mentioned Japanese Patent Application Laid-Open No. 58-112601 is such that the tip of the trailing sheet bar that has been unwound and fed out is welded to the tail end of the leading sheet bar. The present invention is characterized in that a looper device for looping the bar is provided so that the welding can be easily performed with a fixed welding machine. Further, the rolling line proposed in JP-A-58-209405 is characterized in that the looper device proposed in JP-A-58-112601 is replaced by a spiral looper so that the overall length of the rolling line can be shortened. Here, as a method of heating the rolled material such as the sheet bar, heating with a gas burner, heating with an induced current, etc. are generally considered, but these methods are not advantageous in terms of thermal efficiency because of heat dissipation. On the other hand, an energization heating method using an end energization heating device proposed in JP-A-55-161501, which heats a metal material by energizing it, has high thermal efficiency and is advantageous because it directly energizes and heats the object to be heated. This is a great method.
Therefore, it is desirable to heat the sheet bar using the electrical heating method described above.

[Problems to be solved by the invention]

However, when the sheet bar is electrically heated at the entrance side of the rolling mill using the electrical heating method as described above,
Stray currents that flow from the electrodes through the sheet bar to the rolling rolls of the rolling mill are likely to occur. Because the stray current electrically contacts the rolling roll bearing,
This may cause equipment damage. In order to prevent the stray current from flowing, it is possible to insulate the rolling mill, but there are technical difficulties in rolling mills with high rolling pressure, and an effective insulation method for such rolling mills has yet to be developed. It has not been. Therefore, the above-described current heating method has a problem in that it is not sufficiently used as a heating method for rolled materials such as sheet bars.

[Purpose of the invention]

The present invention has been made in view of the above-mentioned conventional problems, and is capable of preventing stray current from flowing from an electrode through the rolling material to the rolling mill when heating the rolled material with electricity. It is an object of the present invention to provide a method for heating a rolled material by applying electricity, which does not cause damage due to electric contact caused by an electric current.

[Means to solve the problem]

The present invention provides a method for energizing and heating a rolled material in which the rolled material being rolled in a rolling mill is energized using an electrode to heat the rolled material, in which: A rolling mill side that is rolling the same rolled material in a rolling state in which the same rolled material is not bitten at the same time in the front rolling mill and the rear rolling mill using at least one pair of electrodes provided along the conveyance direction. The above object is achieved by energizing the rolled material using the electrode as a ground electrode.

[Effect]

In the present invention, when the rolled material being rolled is heated by passing electricity between the rolling mills, in a rolling state where the same rolled material is not bitten at the same time in the front rolling mill and the rear rolling mill,
The rolled material is energized and heated by at least one pair of electrodes, which are arranged on a conveyance path between the front rolling mill and the rear rolling mill, and have an electrode on the side of the rolling mill that is rolling the rolled material as a ground electrode. do. Also, when heating a wound sheet bar by applying electricity during unwinding and rolling, at least one pair of electrodes should be connected to the rolling mill, with the electrode on the side of the rolling mill that is rolling the material being the ground electrode. Turn on electricity and heat it. Therefore, the rolling mill and the electrode on the side of the rolling mill are at the same ground potential and no potential difference occurs, so that it is possible to prevent stray current from flowing from the electrode through the rolled material to the rolling mill. Therefore, electrical contact troubles caused by the stray current flowing in the rolling roll bearings of the rolling mill can be prevented without reinforcing the insulation of the rolling mill. The material can be heated by being energized using an energization heating method. Therefore, since the rolled material can be efficiently heated on the entry side of the rolling mill, the quality of the rolled material can be stabilized, and the rolled material can be easily joined on the entry side of the rolling mill.

【Example】

Embodiments to which the present invention is applied will be described in detail below. In this embodiment, a seat bar 10 as shown in FIG.
The present invention relates to an electrical heating device for heating. In the figure, a roughing mill 12 is arranged to roll and feed out the sheet bar 10 on a table roll 14 in the direction of a finishing mill 16 . A pair of current-carrying electrodes 18A and 18B are arranged along the conveying direction of the sheet bar 10 in contact with the sheet bar 10 on the table roll 14 to energize and heat the sheet bar 10. . The electrodes 18A, 18
B is a switching device 20 that switches the power supply connection.
A, 20B, power supply device 22 and ground electrode 24
It is connected to the. On the other hand, in order to detect the timing when rolling of the sheet bar 10 is completed in the rough mill 12, a load cell 24 is disposed on the rough mill 12, or a hot piece detector 26 is disposed on the outlet side of the rough mill 12. has been done. Further, the table roll 14 is insulated by a pedestal (not shown) that supports the table roll 14. Therefore, the heating current is
It flows between 8A, 18B and the seat bar 10. Further, as the electrodes 18A and 18B, either a press-type roll electrode or a clamp-type electrode can be used. The operation of this embodiment will be explained below. As shown in FIG. 1, when the sheet bar 10 is sent out while being rolled from the rough mill 12 and is not bitten by the finishing mill 16, the electrode 18A
is connected to the ground electrode 24 by the switching device 20A and becomes the same as the ground potential, and at the same time, the electrode 18B
is connected to the power supply device 22 by the switching device 20B and becomes the power supply potential. At that time, switching device 2
0A and 20B are switched to the positions shown by solid lines in FIG. Then, the current flows from the power source 22 to the switching device 20B, the electrode 18B, the seat bar 10, the electrode 18A, the switching device 20A, and the ground electrode 24, heating the seat bar 10. that time,
Since the circuit connecting the rough mill 12 and the electrode 18A via the sheet bar 10 is kept at approximately ground potential, the current flowing through the roll bearing of the rough mill 12, that is, the stray current, is extremely small. There will be no electrical contact problems. On the other hand, the sheet bar 10 in the rough mill 12
When rolling is completed, the timing of completion is
It is detected by the load cell 24 or the hot piece detector 26. Depending on the detected timing,
The switching devices 20A, 20B are switched. At that time, the switching devices 20A and 20B
It switches to the position shown by the broken line in FIG. Then,
The current flows from the power supply 22 to the switching device 20B, the electrode 18A, the seat bar 10, the electrode 18B, the switching device 20A, and the ground electrode 24 in this order to heat the seat bar 10. At that time, the seat bar 10
Even if the finishing mill 16 is bitten by the finishing mill 16, the finishing mill 1
6 and the electrode 18B via the seat bar 10 is maintained at approximately ground potential. Therefore, like the roughing mill 12, there is almost no stray current flowing through the roll bearings of the finishing mill 16, and no electrical contact troubles occur in the roll bearings. As described above, in this embodiment, the load cell 24 or the hot piece detector 26 detects the rolling end timing of the rough mill 12 and accurately switches the electrodes 18A and 18B, so that the current flows to the rough mill 12 and the finishing mill 16. The sheet bar 10 can be electrically heated while reliably preventing the sheet bar 10 from flowing. In addition, although the sheet bar 10 was illustrated as a rolled material in the said Example, the rolled material is not limited to this, and other rolled materials may be used as long as it is a rolled material that can be energized. Furthermore, the above embodiment is an example of electrical heating between a normal roughing mill and a finishing mill.
−112601, when a sheet bar winding machine and an unwinding machine are installed between a rough mill and a finishing mill, and the sheet bar is joined by a welding machine for continuous rolling, the sheet bar is created using a continuous casting machine, wound, and then unrolled. The same applies when rolling is performed.

【Effect of the invention】

As explained above, according to the present invention, when heating the rolled material by applying electricity, it is possible to prevent stray current from flowing from the electrode to the rolling mill through the rolled material. Therefore,
Electric contact troubles caused by the stray current flowing in the rolling roll bearings of the rolling mill can be prevented without reinforcing the insulation of the rolling mill. Further, since the stray current does not flow, it is possible to use the current heating method even in a rolling mill with a high rolling pressure, and the rolled material can be heated efficiently. Therefore, since the rolled material can be heated effectively, the quality of the rolled material can be stabilized,
This has an excellent effect in that the rolled materials can be easily joined on the inlet side of the rolling mill.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view, partially including a block diagram, showing an embodiment of the method of energizing a rolled material to which the present invention is applied. 10... Sheet bar, 18A, 18B... Electrode, 2
0A, 20B...Switching device, 22...Power supply device,
24...Grounding electrode.

Claims (1)

[Scope of Claims] 1. A method for energizing and heating a rolled material in which the rolled material being rolled in a rolling mill is heated using an electrode, comprising: a conveyance system for the rolled material between a front rolling mill and a rear rolling mill; Rolling the rolled material using at least one pair of electrodes provided along the conveyance direction on the road in a rolling state in which the same rolled material is not bitten by the front rolling mill and the rear rolling mill at the same time. A method for energizing and heating a rolled material, characterized in that the rolled material is energized using an electrode on the side of a rolling mill as a ground electrode.