JP2004307962A - Apron and hot-rolling facility arranging the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce the development of erosion and crack by effectively restraining the development of eddy current. <P>SOLUTION: A flat-platy state center apron 18 is arranged on the center line between inductors 5b, 5b in an induction heating apparatus 1 for heating the edge parts of a heating material 7 by oppositely disposing while interposing the heating material 7. In this center apron 18, notching grooves 19 standing in low and having prescribed intervals in the induction heating apparatus direction oppositely disposed in the upper surface flatness part, that is, in the thickness direction, are formed. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to an apron installed between transport rollers and a hot rolling facility provided with the apron.
[0002]
[Prior art]
In general, in a hot rolling facility, a material to be heated is heated to a predetermined temperature in advance, continuously conveyed, passed through a plurality of rolling mills, and sequentially rolled to form a thin plate. There is a problem in that the heated material gradually dissipates heat at both ends thereof during the transportation process, and the temperature of this portion gradually decreases as compared with the central portion. If the end part temperature drops and the whole temperature is rolled while the temperature is not uniform, the quality of the rolled steel sheet will not be constant, the hardness of the side end part will increase, the material to be heated will be cracked, and the rollers of the rolling mill will be worn down And other problems occur. For this reason, generally, an induction heating device is installed upstream of the rolling mill of the hot rolling facility, in which both ends of the material to be heated are locally heated with inductors to make the whole substantially constant temperature and then rolled. Have been.
For example, in the induction heating device 1 shown in FIG. 10, the iron core 2 is formed in a C shape, and the upper iron leg 4a and the lower iron leg 4b which are vertically opposed to each other across the opening 3 of the C iron core 2 are heated. Two C-shaped inductors 6a and 6b formed by winding a coil to form an upper inductor 5a and a lower inductor 5b are arranged to face each other. As shown in FIG. 11, the C-shaped inductors 6a and 6b are arranged between the front and rear transport rollers 9 and 9. Further, in order to prevent the bent tip of the heated material 7 conveyed on the conveying rollers 9 and 9 from falling down between the conveying rollers 9 and to prevent the heated material from contacting the inductor. For this purpose, a center apron 8 is provided on the center line between the opposing lower inductors 5a and 5b.
[0003]
When the both ends of the material 7 to be heated are locally heated by the induction heating device 1, the ends of the material 7 to be heated are passed through the openings 3 of the C-shaped inductors 6a and 6b, and a heating coil is supplied from a power source. A high-frequency current is applied to generate a magnetic flux in the vertical direction. The magnetic flux is vertically linked to the material to be heated 7 to induce an eddy current in the material to be heated 7 and generate Joule heat by the eddy current to locally heat both end portions of the material to be heated 7. I am trying to do it.
[0004]
[Patent Document 1]
JP-A-8-69866 [0005]
[Problems to be solved by the invention]
However, leakage magnetic flux is generated from the C-shaped inductors 6a and 6b, and this leakage magnetic flux penetrates the tip of the center apron 8, and the leakage magnetic flux generates a large eddy current. This current generates Joule heat, and when heating by this Joule heat proceeds, it causes the vicinity of the upper end of the center apron 8 to be melted or cracked.
[0006]
On the other hand, in the induction heating apparatus 1 shown in FIG. 10 described above, a closed loop circuit is formed between the material 7 to be heated in the middle of conveyance and the conveyance rollers 9, 9. An electromotive force is generated in this loop circuit, and an induced current flows. This induced current becomes a ground current via the transport rollers 9, 9, but when there is a slight gap between the heated material 7 and the transport rollers 9, 9, the induced current flows to the heated material 7. Arc discharge is generated, and in some cases, there is a problem that an arc mark is generated on the material 7 to be heated and becomes an unnecessary product.
[0007]
Therefore, in order to avoid this, the present inventors set the heating coil so that the magnetic flux direction of the adjacent C-shaped inductor and the magnetic flux direction of the C-shaped inductor facing each other with the material to be heated interposed therebetween are opposite to each other. A wound induction heating device has been proposed (see Patent Document 1 (Japanese Unexamined Patent Application Publication No. 8-69866)). According to this prior example, since the directions of the magnetic fluxes cancel each other, the generation of the electromotive force is suppressed and the induced current becomes difficult to flow, so that the occurrence of the arc discharge described above can be prevented.
[0008]
However, when the magnetic flux direction of the C-shaped inductor 6a and the magnetic flux direction of the C-shaped inductor 6b opposed to each other with the material to be heated 7 being opposite to each other, the influence of the leakage magnetic flux generated from the C-shaped inductors 6a and 6b. Is particularly problematic. That is, as shown in FIG. 10, the leakage magnetic flux Φ goes from the opposed inductors 6a to 6b and from the opposed inductors 6b to 6a. For this reason, Joule heat is generated near the upper end of the center apron 8 due to the eddy current caused by the leakage magnetic flux. As heating by the Joule heat proceeds, the vicinity of the upper end of the center apron 8 is melted as described above. This has been a factor that causes damage and cracks.
[0009]
In view of the above circumstances, an object of the present invention is to provide an apron that can effectively suppress the generation of eddy currents and reduce the generation of erosion and cracks, and a hot rolling facility using the same.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is a hot rolling facility in which induction heating devices for heating both side ends of a conveyed material to be heated are arranged to face each other with the material to be heated interposed therebetween. An apron installed between the two induction heating devices, wherein a notch groove is formed at predetermined intervals in a direction of the induction heating device opposed to the flat upper surface. .
[0011]
According to the above configuration, as shown in FIG. 4, even if a leakage magnetic flux is generated between the induction heating devices arranged opposite to each other and a large eddy current loop is generated in the apron due to the leakage magnetic flux, the generated eddy current is generated. Since the loop is divided by the notch groove and exists only in a small area, it is possible to effectively suppress the generation of a large eddy current and reduce the erosion and cracks at the upper end of the apron. It is possible to do.
[0012]
According to a second aspect of the present invention, in the apron according to the first aspect, the notch grooves are formed by alternately arranging adjacent grooves having different depths.
[0013]
According to the above configuration, it is possible to effectively suppress the generation of the eddy current and reduce the generation of the erosion and the crack while maintaining the strength of the upper end portion.
[0014]
According to a third aspect of the present invention, in the apron according to the first or second aspect, the cutout groove is a groove that is inclined with respect to the direction of the induction heating device that is disposed to face or a groove that is curved in an arc shape. It is assumed that.
[0015]
According to the above configuration, while maintaining the strength and the threading property of the upper end of the apron (preventing the tip of the heated material from being caught), the generation of eddy current is effectively suppressed, and the generation of erosion and cracks is reduced. It is possible to do.
[0016]
According to a fourth aspect of the present invention, in the apron according to any one of the first to third aspects, an intake for introducing cooling water into the apron, a drain for discharging the cooling water, the intake and the drain are provided. And a cooling water passage for cooling the vicinity of the notch groove with the introduced cooling water is provided.
[0017]
According to the above configuration, it is possible to suppress the temperature rise at the upper end of the apron by the Joule heat caused by the eddy current generated in the vicinity of the notch groove, so that it is possible to reduce the erosion and crack generation by the Joule heat. Become.
[0018]
According to a fifth aspect of the present invention, in the apron according to any one of the first to fourth aspects, the apron includes a main body, a notch groove forming portion in which the notch groove is formed, and a side portion. And, the main body portion and the notch groove forming portion are connected by a welding portion,
The length from the upper end of the notch groove forming portion to the welding portion has a predetermined distance which is hardly affected by heat generated by magnetic flux.
[0019]
According to the above configuration, in the welded portion, leakage magnetic flux is generated between the induction heating devices arranged opposite to each other, and the leakage magnetic flux generates an eddy current in the upper portion of the apron. Since it is not received, it is possible to prevent the welded portion from peeling off due to overheating, and it is possible to prevent leakage of cooling water due to the peeling.
[0020]
According to a sixth aspect of the present invention, there is provided a hot-rolling facility wherein the apron according to any one of the first to fifth aspects is provided between transport rollers for transporting the material to be heated.
[0021]
According to the above configuration, by providing the notch groove at the upper end of the apron, it is possible to effectively suppress the generation of eddy current and reduce the occurrence of erosion and cracks while maintaining the strength of the upper end of the apron. In addition, by providing a cooling water passage in the apron and flowing cooling water, it is possible to suppress a rise in the temperature of the upper end of the center apron due to Joule heat caused by the eddy current generated near the notch groove at the upper end of the apron. Hot rolling equipment can be configured.
[0022]
According to a seventh aspect of the present invention, there is provided a hot-rolling equipment wherein the apron according to any one of the first to fifth aspects is provided above and below the material to be heated between transport rollers for transporting the material to be heated. is there.
[0023]
According to the above configuration, since the apron is provided not only on the lower side but also on the upper side, even when the heated material tip is conveyed in a state of being warped upward, the warp is caused by the upper apron. As a result, the board is prevented from being caught, and the sheet passing property is further improved.
[0024]
BEST MODE FOR CARRYING OUT THE INVENTION
1 and 2 show a main configuration of a hot rolling facility to which the apron according to the present invention is applied. In each drawing, the same components as those in FIGS. 10 and 11 described above are denoted by the same reference numerals.
[0025]
As shown in the figure, a non-magnetic material such as, for example, a non-magnetic material is provided on a center line between the inductors 5b and 5b of the induction heating device 1 which is disposed to face the material to be heated 7 and heats an end of the material to be heated 7. A center apron 18 made of austenitic stainless steel is provided. As shown in FIG. 2, the center apron 18 prevents the bent tip of the heated material 7 conveyed on the conveying rollers 9, 9 from falling down between the conveying rollers 9 and sneaking in. This is provided to maintain the so-called plate passing property.
[0026]
In particular, as shown in FIG. 3, the center apron 18 in the present embodiment has a predetermined interval (pitch P) in the direction of the induction heating device arranged opposite to the flat portion of the upper surface, that is, in the thickness direction. The aligned notch grooves 19 are formed.
[0027]
The notch groove 19 has a function of reducing the generation of eddy current due to the leakage magnetic flux directed from the opposing inductors 6a to 6b.
[0028]
That is, as shown in FIG. 4, the eddy current generated near the upper end of the center apron 18 becomes a large eddy current loop when there is no notch groove 19. However, when the notch groove 19 is provided as in the present embodiment, the generated eddy current is limited to a small region between the adjacent notch grooves 19, and a large eddy current extending in the apron width direction. Since the generation of current is suppressed, the resulting eddy current has an extremely small value. For this reason, the generated Joule heat is also low, and it is possible to reduce erosion and crack generation near the upper end. In particular, since the center apron 18 in the present embodiment is made of a non-magnetic austenitic stainless steel, it is difficult to pass the leakage magnetic flux caused by the generation of the eddy current, and the generation of Joule heat can be further reduced. .
[0029]
Further, as shown in FIG. 5, the pitch P of the notch grooves 19 is determined in relation to the maximum loss density, and it is considered that a maximum loss density of about 30 mm is suitable.
[0030]
In the present embodiment, an intake port 20 and a drain port 21 are provided on the lower side surface of the center apron, and a cooling water passage 22 is provided inside the center apron.
[0031]
In order to form the cooling water passage 22, the center apron 18 is formed with a main body 18A shown in a front view of an arrow A in FIG. 3, a notch groove 19, and a side surface of an arrow B in FIG. As shown in the figure, a notch groove forming portion 18B in which a groove for a cooling water channel is formed, and a groove for a cooling water channel is formed inside as shown in a bottom view of an arrow C in FIG. And a pair of left and right side portions 18C. These four portions are connected by welding to be integrated. In addition, from the tip of the notch groove forming portion 18B to the welding portion 30, the above configuration having a predetermined length L so as not to be directly affected by Joule heat caused by eddy current generated by leakage magnetic flux. In the center apron 18, the cooling water introduced from the water intake 20 flows through the cooling water channel 22 near the lower part of the notch 19 of the center apron 18, and is discharged to the outside from the drain 21. At this time, the temperature rise at the upper end of the center apron can be suppressed by the Joule heat generated by the eddy current generated in the vicinity of the notch groove 19, so that the erosion and crack generation due to the Joule heat can be reduced.
[0032]
Also, as described above, since the welded portion 30 has a predetermined length L from the tip of the notch groove forming portion 18B to the welded portion 30, as shown in FIG. It is less likely to be heated by heat, and it is possible to prevent the welding portion 30 from peeling off due to the heating and leaking the cooling water.
[0033]
FIG. 7 shows experimental data for verifying the effect of the present embodiment, and this figure shows the temperature transition when there is no notch groove (slit) and when there is a notch groove (slit).
[0034]
When the induction heating device (edge heater) is turned on and operated at full power, the temperature at the upper end of the center apron rapidly increases with time. In the case of the lower center apron without a slit, the temperature rose to about 1300 ° C. after 30 minutes. After 50 minutes, the temperature rose to about 1400 ° C. When this state is continued, the upper end of the center apron is gradually melted and eroded.
[0035]
On the other hand, in the case of the lower center apron having the notched groove, the temperature rose to about 900 ° C. after 30 minutes, but it was found that there was no further rise and the temperature remained constant. It was also found that the temperature change in the upper center apron (with slits), which is described later, was almost the same as that in the lower center apron.
[0036]
As described above, in the case where the notched groove is provided, a temperature decrease of several hundred degrees Celsius was confirmed as compared with the case where the notched groove was not provided, and the effectiveness of the notched groove was verified.
[0037]
<Other embodiments>
FIG. 8 shows another embodiment of the center apron according to the present invention.
[0038]
In the center apron 18 of this embodiment, notched grooves 23 of deep grooves and notched grooves 24 of shallow grooves are alternately arranged.
[0039]
Thus, by alternately arranging the notch grooves 23 having a deep groove and the notch grooves 24 having a shallow groove, it is possible to effectively suppress the generation of eddy current while maintaining the strength of the end portion. It is possible to reduce the occurrence of erosion and cracks.
[0040]
FIG. 9 shows still another embodiment of the center apron according to the present invention. In the example shown in the figure, the notch groove of the center apron 18 is formed by a groove inclined with respect to the direction of the induction heating device or a groove curved in an arc shape, which is opposed to the center apron 18.
[0041]
The center apron 18 shown in (A) is one in which oblique grooves 25 that are inclined at a predetermined angle with respect to the direction of the induction heating device that is arranged oppositely are arranged.
[0042]
The center apron 18 shown in (B) has grooves 26 which are curved in a semicircular shape when viewed from a plane, and the center apron 18 shown in (C) has a substantially quadrant shape when viewed from a plane. The curved grooves 27 are arranged in a line.
[0043]
As described above, by forming the notch groove 25 inclined at an angle or the notch grooves 26 and 27 curved in an arc shape, the generation of the eddy current is effectively suppressed while maintaining the strength of the upper end portion. As a result, the occurrence of erosion and cracks can be reduced.
[0044]
In the notch grooves 25, 26, and 27 shown in FIG. 9, deep grooves and shallow grooves may be alternately arranged as shown in FIG.
[0045]
With this configuration, it is possible to effectively suppress the occurrence of eddy currents and reduce the occurrence of erosion and cracks while maintaining the strength of the upper end portion.
[0046]
Also, by providing the center aprons 18, 28, 38 having the notched grooves shown in FIGS. 1 to 9 between the conveying rollers in the hot rolling equipment, the generation of the eddy current near the upper end of the center apron is reduced. By effectively suppressing or cooling, it is possible to reduce the occurrence of erosion and cracks.
[0047]
Further, in each of the above embodiments, the configuration in which the center apron 18 is installed only on the lower side has been described. However, for example, as shown in FIG. You may make it oppose apron 18 and arrange.
[0048]
As shown in FIG. 7, the transition of the apron temperature when the upper center apron 31 is used is slightly lower than that of the lower center apron 18 but shows the same tendency, and the effectiveness of the notch groove (slit) is shown. Has been demonstrated.
[0049]
Thus, according to the hot rolling equipment configured to dispose the upper center apron 31 so as to face the lower center apron 18 with the material 7 to be interposed therebetween, the heated roll conveyed over the conveying rollers 9, 9 The lower center apron 18 prevents the bent front end of the material 7 from falling down into the conveyance roller 9 and sneaks down, and the case where the front end of the material 7 to be heated is conveyed upward. However, warpage is restricted by the upper center apron 31, thereby preventing the board from being caught, thereby further improving the sheet passing property as compared with the case where only the lower center apron 18 is used.
[0050]
【The invention's effect】
As described above, according to the present invention, it is possible to effectively suppress the generation of eddy currents or to reduce the occurrence of erosion and cracks by cooling.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a main configuration of a hot rolling facility to which an apron according to the present invention is applied.
FIG. 2 is an explanatory diagram showing a main configuration of a hot rolling facility to which the apron according to the present invention is applied.
FIG. 3 is an explanatory view showing an embodiment of an apron according to the present invention.
FIG. 4 is an explanatory view schematically showing the action of a notch groove.
FIG. 5 is a characteristic diagram showing a relationship between the maximum loss density on the surface of the notched groove and the pitch.
FIG. 6 is an explanatory diagram showing an arrangement position of a welded portion and showing a configuration in which an upper center apron is arranged.
FIG. 7 is an explanatory diagram showing a temperature transition when there is a slit and when there is no slit.
FIG. 8 is an explanatory view showing another embodiment of the apron according to the present invention.
FIG. 9 is an explanatory view showing still another embodiment of the apron according to the present invention.
FIG. 10 is an explanatory diagram showing a relationship between an induction heating device and an apron in a hot rolling facility.
FIG. 11 is an explanatory diagram showing a relationship between an induction heating device and an apron in a hot rolling facility.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Induction heating device 2 C-shaped iron core 3 Opening 4a Upper core leg 4b Lower iron leg 5a Upper inductor 5b Lower inductor 6a C-shaped inductor 6b C-shaped inductor 7 Heated material 9 Transport roll 18 Center apron (lower center apron)
18A Main body part 18B Notch groove forming part 18C Side part 19 Notch groove 20 Intake port 21 Drain port 22 Cooling water channel 23, 24, 25, 26, 27 Notch groove 30 Welding part 31 Upper center apron

Claims (7)

An apron installed between the induction heating devices in a hot-rolling facility in which induction heating devices for heating both side ends of the conveyed material to be heated are disposed opposite to each other with the material to be heated interposed therebetween. ,
An apron characterized by forming notch grooves arranged at predetermined intervals in the direction of an induction heating device disposed opposite to a flat upper surface. The apron according to claim 1,
An apron, wherein the notch grooves are formed by alternately arranging adjacent grooves having different depths. The apron according to claim 1 or 2,
The apron, wherein the notch groove is a groove that is inclined with respect to the direction of the induction heating device that is disposed opposite to the groove or a groove that is curved in an arc shape. The apron according to any one of claims 1 to 3,
An intake for introducing cooling water into the apron,
A drain for discharging the cooling water,
A cooling water passage that connects the water intake and the drain, and cools the vicinity of the notch groove with the introduced cooling water,
An apron characterized by having provided. The apron according to any one of claims 1 to 4,
The apron is composed of a main body, a notch groove forming part in which the notch groove is formed, and a side part, and the apron main body and the notch groove forming part are connected by a welding part. And
An apron, wherein a length from an upper end of the notch groove forming portion to the welding portion has a predetermined distance which is hardly affected by heat generated by magnetic flux. A hot rolling facility, wherein the apron according to any one of claims 1 to 5 is provided between conveying rollers for conveying the material to be heated. A hot-rolling facility, wherein the apron according to any one of claims 1 to 5 is provided above and below the material to be heated between transport rollers for transporting the material to be heated.

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