JPH0137835B2 - - Google Patents

Description

[Detailed description of the invention]

[Field of Application of the Invention] The present invention relates to an apparatus for electrically heating a metal strip. [Background of the Invention] Generally, methods for heat-treating metal strips are disclosed in Japanese Patent Application Laid-open No. 49-122806 and Japanese Patent Application Laid-Open No.
As disclosed in Japanese Patent No. 58-96826, a method is known in which a current is passed through a metal strip to heat it using module heat. However, since power is supplied to the metal strip by a current-carrying roller,
Sparks are likely to occur between the current-carrying roller and the metal strip, and spark scratches will occur on the surfaces of both the metal strip and the current-carrying roller where the spark occurred. This resulted in a shortened lifespan of the current-carrying roller and a deterioration in the quality of the metal strip. [Object of the Invention] An object of the present invention is to provide an electrical heating device for a metal strip that prevents the generation of sparks and does not cause spark damage. [Summary of the Invention] In order to achieve the above object, the present invention involves winding a metal strip around the outer peripheral surface of a current-carrying roller that receives power from a power supply device, and applying current to the metal strip while rotating the current-carrying roller. In a device that performs heating by flowing water, grooves extending in the axial direction of the energizing roller are provided at intervals in the circumferential direction on the outer circumferential surface of the energizing roller, and electrodes are placed in each of the grooves so that the tip surface of the energizing roller extends along the outer periphery of the energizing roller. The metal strip is fitted through an insulator so that it protrudes from the surface, and the electrodes are arranged so that the gap between them makes an angle of 15 degrees or less with respect to the rotating shaft of the current-carrying roller, and the metal strip and the electrode are in contact with each other. The present invention is characterized in that power is supplied only to the electrodes existing in a range excluding the contact start and end positions of both sides and their vicinity. [Embodiments of the Invention] Next, embodiments of the present invention will be described based on the drawings. First, the principle of the present invention will be explained. Sparks that occur between the metal strip and the current-carrying roller often occur at and near the locations where the metal strip and the current-carrying roller begin and end contact. Therefore, in order to prevent the generation of sparks, it is conceivable to not supply power to the start and end positions of contact between the metal strip and the current-carrying roller. For this purpose, as shown in FIG.
An electrode 4 is fitted into the electrode 4 through an insulator 3, and power is supplied only to the electrode within a range of an angle β smaller than the angle α at which the metal strip 5 is wound around the electrode 4.
By doing this, power is not supplied to the contact start and end positions between the metal strip 5 and the electrode 4, where the contact is unstable, and the vicinity thereof, but the opposite electrode 4
The surrounding insulator 3 and the metal strip 5 came into contact, resulting in poor contact between the electrode 4 and the metal strip 5, and sparks were generated. That is, since the electrode 4 and the insulator 3 on the outer periphery of the roller 1 are not on a perfect circular arc, a part of the metal strip 5 is supported by the insulator 3 on the outer periphery, and the contact pressure to the electrode 4 is small or extremely small. A gap is created and sparks are generated. Therefore, as shown in FIG. 2, a step h is provided on the electrode 4 attached via the insulator 3 to ensure that the metal strip 5 contacts only the electrode 4.
Furthermore, each electrode 4 is arranged so that the angle (hereinafter referred to as gap angle) γ of the gap A between adjacent electrodes 4a and 4b with respect to the current-carrying roller rotation axis B is 15° or less, and the feeding angle β When I supplied power only to the range of , there was no sparking at all. If the electrode gap angle γ is large, the metal strip 5 will be near the end of the electrode 4 (range C in the figure) as shown in FIG.
It was confirmed that there was a gap in the central part of the electrode (range D in the figure), contact was uncertain, and sparks were generated. From the above, in order to prevent sparks, it is necessary to provide a step in the electrode 4 and keep the gap angle γ between adjacent electrodes to 15 degrees or less, excluding the position where the metal strip and the electrode start and end contact and the vicinity thereof. The conclusion was reached that it is effective to supply electricity. Next, FIG. 4 shows an embodiment of the present invention, FIG. 5 shows a cross-sectional view of FIG. Details of the mounting part are shown. A plurality of electrodes 4 are dividedly arranged around the outer periphery of the energizing roller 1 and attached to the energizing roller main body 6 via an insulator 3. In detail, as shown in FIG. 6, the insulating washer 7 is completely insulated from the current-carrying roller main body 6 by an insulating collar 8, and is attached with a bolt 9. The energizing roller 6 is located in the insulating room 10
It is rotatably supported by bearings 11a and 11b on the outside of the roller 1, and seals 12a and 12b are provided at the portions where the current-carrying roller 1 passes through the insulation chamber 10 in order to improve the heat retention effect of the insulation chamber 10. Power is supplied to the electrode 4 by the brush 1, which is given appropriate contact pressure by a spring 14 built into the brush holder 13.
5. The brush 15 supplies power to the electrode 4.
The range of the power feeding range is limited to the range of the angle β, which is smaller than the winding angle α of the metal strip 5. The electrodes 4 are made higher than the energizing roller main body 6, and a step h is provided so that the angle (i.e., the electrode gap angle) γ between adjacent electrodes 4 with respect to the energizing roller rotation axis is 15° or less. It is located. The electrode 4 is made of heat-resistant cast steel because it comes into contact with the high-temperature metal strip 5, and includes an insulator 3, a seal 12a,
12b has a high temperature, so ceramic and
It is desirable to use materials such as asbestos.
The brush 15 can be made of commonly used carbon from the viewpoint of slipperiness. FIG. 7 shows an outline of an electrical heating device to which the present invention is applied. The current applied to the metal strip 5 is
From the energizing roller 16 through the metal strip 5
The current is passed through the path to the current-carrying roller 17 and the third power-feeding roller 18, and the current generates heat in the metal strip 5 due to Joule heat. The electrodes 4 are arranged separately on the first to third energizing rollers 16 to 18 as described above, and the insulating chamber 10 is provided to surround the metal strip 5 so that the metal strip 5 can generate heat efficiently. There is. With the above configuration, it was possible to completely prevent sparks and heat the metal strip.

〔Effect of the invention〕

As explained above, according to the present invention, a metal strip can be electrically heated while completely preventing spark damage.

[Brief explanation of drawings]

Figure 1 is a cross-sectional view of the current-carrying roller that is the basis of the present invention, Figure 2 is a cross-sectional view of the current-carrying roller that explains the invention, Figure 3 is an explanatory view of the vicinity of the electrodes that explains the generation of sparks, and Figure 4 is an axial cross-sectional view of an energizing roller showing an embodiment of the present invention, FIG. 5 is a cross-sectional view taken along the - cross-sectional arrow in FIG. 4, and FIG.
FIG. 7 is a layout diagram of an electrical heating device to which the present invention is applied. 1... Current roller, 2... Groove, 3... Insulator,
4... Electrode, 5... Metal strip, 6... Energizing roller body, 7... Insulating washer, 8... Insulating collar, 9... Bolt, 10... Insulating chamber, 11a,
11b...Bearing, 12a, 12b...Seal, 1
3...Brush retainer, 14...Spring, 15
... Brush, 16 ... Second energizing roller, 17 ...
First energizing roller, 18...Third energizing roller, α...
...Wrapping angle, β...Power feeding range angle, γ...Angle of electrode gap, A...Electrode gap, B...Power feeding roller rotation axis, C...Near the end of the electrode, D...Near the center of the electrode, h ...Level of electrode.

Claims (1)

[Scope of Claims] 1. A device that heats the metal strip by winding a metal strip around the outer peripheral surface of a current-carrying roller that receives power from a power supply device, and passing a current through the metal strip while rotating the current-carrying roller, comprising: Grooves extending in the axial direction of the energizing roller are provided at intervals in the circumferential direction on the outer circumferential surface of the energizing roller, and electrodes are placed in each of the grooves with an insulator interposed therebetween, with their tip surfaces protruding from the outer periphery of the energizing roller. and the electrodes are arranged so that the gap between them makes an angle of 15 degrees or less with respect to the rotating shaft of the current-carrying roller, and
1. An electrical heating device for a metal strip, characterized in that, on the contact surface between the metal strip and the electrode, power is supplied only to the electrodes existing in a range excluding the contact start and end positions of both and the vicinity thereof.