JP2009228072A - Method for suppressing vibration of hearth-roll, and annealing furnace - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the vibration of a hearth-roll and also, the generation of flaw on the surface of a steel sheet. <P>SOLUTION: An annealing furnace for steel sheet which anneals the steel sheet 100 while conveying the steel sheet 100, is provided with first to sixth hearth rolls 4<SB>1</SB>-4<SB>6</SB>which are rotatably supported on a furnace body 3 and convey the steel sheet 100, and a controlling part 5 for controlling the number of rotations of the first to sixth hearth-rolls 4<SB>1</SB>-4<SB>6</SB>. The controlling part 5 performs control to make the number of rotations of one hearth-roll different from that of its adjacent hearth-roll in the first to sixth hearth-rolls 4<SB>1</SB>-4<SB>6</SB>. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a vibration suppressing method for a hearth roll for conveying a steel plate in an annealing furnace and an annealing furnace.

In the annealing furnace, the steel sheet is conveyed by a hearth roll (conveyance roll). Both ends of the hearth roll are rotatably supported by the annealing furnace. In such an annealing furnace, it is important in order to improve the quality of a product to suppress the flaw which generate | occur | produces on the steel plate surface during conveyance. For example, Patent Document 1 discloses a technique for preventing surface flaws by evaluating the occurrence of fluttering.
JP-A-9-291315

By the way, when the hearth roll vibrates, a wrinkled surface is generated in the width direction of the steel plate. For this reason, it is necessary to prevent the vibration of the hearth roll. However, the technique disclosed in Patent Document 1 cannot solve such a problem.
In addition, as a vibration prevention technique for the hearth roll, there are a technique for suppressing the bending of the hearth roll as a vibration source, and a technique for holding the hearth roll bearing part independently from the furnace body. Alternatively, when the hearth roll bearing is held by the furnace body itself, there are some which reinforce the furnace body. However, when the hearth roll is thin, or when the hearth roll bearing is held by the furnace body, a large design change is required to cope with the equipment for preventing vibration.
An object of the present invention is to prevent the vibration of the hearth roll with a simple configuration and to prevent generation of wrinkles on the surface of the steel sheet.

In order to solve the above-mentioned problem, the vibration suppression method for the hearth roll according to claim 1 according to the present invention is the annealing furnace for annealing the steel plate while conveying the steel plate, wherein a plurality of hearth rolls are provided on the same support. It is rotatably supported, and the number of rotations of adjacent ones of the plurality of hearth rolls is made different.
Further, the hearth roll vibration suppressing method according to claim 2 of the present invention is the hearth roll vibration suppressing method according to claim 1, wherein the difference in rotation speed between the adjacent hearth rolls is 3% or more. It is characterized by.

According to a third aspect of the present invention, there is provided a hearth roll vibration suppressing method according to the first or second aspect of the present invention, wherein the adjacent hearth roll is adjusted by adjusting a diameter of the adjacent hearth roll. The peripheral speeds of the outer peripheral surfaces of the matching hearth rolls are the same.
Moreover, the annealing furnace of Claim 4 which concerns on this invention is supported in the same support body rotatably in the annealing furnace of the steel plate which anneals the said steel plate while conveying a steel plate, and is a plurality of conveying the steel plate A hearth roll and a control means for controlling the rotation speed of the hearth roll are provided, wherein the control means makes the rotation speeds of adjacent ones of the plurality of hearth rolls different.

  According to the present invention, by making the rotation speeds of adjacent ones of a plurality of hearth rolls different from each other, the resonance of the hearth rolls can be prevented, and the vibration of the hearth rolls can be prevented with a simple configuration, thereby preventing the occurrence of wrinkles. .

The best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described in detail with reference to the drawings.
(Constitution)
The present embodiment is an annealing furnace to which the present invention is applied.
1 and 2 show the configuration of the annealing furnace. FIG. 1 is a cross-sectional view of an annealing furnace as viewed from the side. FIG. 2 is a cross-sectional view of the annealing furnace as viewed from the conveying direction side of the steel plate. This annealing furnace is a horizontal annealing furnace that conveys and anneals the steel plate 100 in the horizontal direction.
As shown in FIG. 1, the annealing furnace forms a furnace body 3 by a furnace shell 1 forming an outer peripheral wall and a heat insulating material 2 provided on the inner peripheral side of the furnace shell 1. As shown in FIG. 2, the furnace body 3 has a substantially rectangular cross section. In the furnace body 3, a steel plate carry-in port 3 a and a carry-out port 3 b are respectively formed on the longitudinal side walls.

The annealing furnace includes a plurality of hearth rolls (first to sixth hearth rolls) 4 ₁ , 4 ₂ , 4 ₃ , 4 ₄ , 4 ₅ , 4 ₆ and a control unit 5 as means for conveying the steel plate 100. Yes. Each of the hearth rolls 4 ₁ to 4 ₆ is installed in the furnace body 3 so as to have substantially equal intervals in the conveying direction of the steel plate 100. As shown in FIG. 2, each of the hearth rolls 4 ₁ to 4 ₆ is supported such that both end portions (for example, bearings) 4 a and 4 a are rotatable with respect to the side wall in the short side direction of the furnace body 3. The hearth rolls 4 ₁ to 4 ₆ are driven using a rotation driving means such as a motor. The control unit 5 controls the rotational speed of each of the hearth rolls 4 ₁ to 4 ₆ by driving and controlling a rotational driving means such as a motor. Specifically, the rotation speed is controlled so that the rotation speeds of adjacent ones of a plurality of hearth rolls are different. That is, as shown in FIG. 1, when a has a hearth roll ₄₁ to ₆ of first to sixth as in the present embodiment, the first hearth rolls 4 ₁ and second hearth rolls 4 ₂ that at different rotational speed and its at different rotational speed in the second hearth rolls 4 ₂ and the third hearth rolls 4 _3, and the third hearth rolls 4 _third and fourth hearth rolls 4 ₄ as in the at different rotational speed, and a fourth of hearth rolls 4 ₄ thereof at different rotational speed between the fifth hearth rolls 4 _5, the fifth hearth rolls 4 ₅ and hearth rolls 4 ₆ 6 Change the rotation speed. Further, the lower limit value of the rotation speed difference between adjacent hearth rolls is 3% (a rotation speed difference of 3% or more).

  Moreover, the diameter of each hearth roll is varied. Specifically, the diameter of the adjacent hearth rolls is adjusted and determined so that the peripheral speeds of the outer peripheral surfaces of the adjacent hearth rolls are the same. For example, the diameter of the hearth roll is generally determined according to the use of the hearth roll. For example, when a 120 mm roll is used as a reference, each hearth roll has a different diameter within a range of about 120 mm so that the peripheral speeds of the outer peripheral surfaces of adjacent hearth rolls are the same.

(Operation, action and effect)
The operation, action and effect are as follows.
When the steel plate 100 is carried into the annealing furnace for annealing, the controller 5 rotates the adjacent hearth rolls while adapting the rotation speed of each of the hearth rolls 4 ₁ to 4 ₆ to the conveying speed of the steel plate 100. Control the number to be different. Thereby, it is possible to prevent vibration of the hearth rolls 4 ₁ to 4 ₆ with a simple configuration, and to prevent a wrinkled wrinkle from occurring in the width direction of the steel plate.

  The inventor of the present application is that the vibrations of the hearth rolls affect each other through the furnace body that forms the support of the hearth rolls, and the resonance is induced and the amplitude is amplified when the phases of the vibrations are aligned. I discovered a mechanism that caused wrinkles. For this reason, by making the rotation speeds of adjacent hearth rolls different, the vibration phase of the hearth rolls is shifted, and the hearth rolls are prevented from resonating. For example, when FFT (FastFourier Transform) analysis is performed on the vibration of the hearth roll, a result that the peak value of the FFT spectrum becomes small can be obtained. In this way, wrinkles are prevented from occurring by preventing resonance of the hearth roll.

  Further, by setting the lower limit value of the rotation speed difference between adjacent hearth rolls to 3% (a rotation speed difference of 3% or more), it is possible to effectively prevent the hearth rolls from resonating. At this time, if there is a difference in the peripheral speed between the outer peripheral surfaces of adjacent hearth rolls, the steel plate and the hearth roll slip and wrinkles occur, so the peripheral speeds of the outer peripheral surfaces of the adjacent hearth rolls are substantially the same. Thus, by making the diameters of the respective hearth rolls different, a difference is caused in the number of rotations of the adjacent hearth rolls. The upper limit of the rotational speed difference is not particularly defined, but since the rotational speed difference is generated by changing the diameter, the effect of preventing wrinkles due to vibration suppression, the viewpoint of equipment constraints, and the cost aspect, The upper limit value can be determined as appropriate.

This embodiment can also be realized by the following configuration.
That is, in this embodiment, the case where the hearth roll is supported on the furnace body has been described. That is, the case where the support body that rotatably supports the hearth roll is a furnace body has been described. On the other hand, a support body can be provided separately from the furnace body, and the hearth roll can be supported by the support body.
Moreover, this embodiment demonstrated the case where an annealing furnace was a horizontal annealing furnace. On the other hand, an annealing furnace having a structure in which a plurality of hearth rolls (a part of a plurality of hearth rolls may be used) is arranged in the vertical direction.

  Moreover, this embodiment demonstrated the case where the annealing furnace was equipped with six hearth rolls. On the other hand, an annealing furnace can also be provided with less than 6 or 7 or more hearth rolls. Even in such a case, in the case where the annealing furnace includes three or more hearth rolls, at least one set of adjacent hearth rolls may have different rotational speeds as described above, or the diameters corresponding thereto. It can also be adjusted. As described above, it is possible to obtain the effect of preventing wrinkles even by changing the rotational speed of some of the hearth rolls, not just for all of the plurality of hearth rolls.

In addition, when multiple hearth rolls are rotated by chain connection, adjusting the transmission ratio between the chain and the hearth roll (for example, a sprocket included in the hearth roll) can also change the rotation speed between adjacent hearth rolls. Can be made.
In this embodiment, the first to sixth hearth rolls 4 ₁ to 4 ₆ are rotatably supported by the same support body, and realize a plurality of hearth rolls for transporting the steel plate, 3 realizes a support for supporting the hearth roll, and the control unit 5 realizes a control means for controlling the number of rotations of the hearth roll, and the control means is adjacent to the plurality of hearth rolls. This makes it possible to vary the number of rotations of matching objects.
Further, in this embodiment, a plurality of hearth rolls are rotatably supported on the same support in an annealing furnace for annealing a steel plate, and the hearth rolls that vary the number of rotations between adjacent ones of the plurality of hearth rolls. The vibration suppression method is realized.

Example 1
The amplitude of the hearth roll (specifically, the amplitude of the bearing portion of the hearth roll) was measured for the case where the rotation number of the hearth roll was the same and the case where the rotation number of the adjacent hearth rolls was different.
3 and 4 show the results of the examples. FIG. 3 shows the amplitude of the hearth roll when the rotation speeds of all the hearth rolls are the same (comparative example). FIG. 4 shows the amplitude of the hearth roll when the rotation speeds of adjacent hearth rolls are different (an example in which the present invention is applied).
As can be seen from a comparison between FIG. 3 and FIG. 4, the amplitude of all the hearth rolls is suppressed by making the rotation speeds of the adjacent hearth rolls different. From this result, when the present invention is applied, an effect of preventing wrinkles can be expected.

(Example 2)
The wrinkles generated on the steel plate were measured.
A grain-oriented electrical steel sheet was used as an applied material, its plate thickness was 0.30 mm, and its plate width was 1200 mm. The equipment used was an annealing furnace for the final annealing line of grain-oriented electrical steel sheets. The operating conditions and processing conditions were such that the annealing plate temperature was 800-850 ° C., the annealing furnace internal tension was 0.8 kg / mm ² , and the line speed was 160 m / min. As an example of the case where the present invention is applied, adjacent hearth rolls are changed within a range of rotation speeds 399.3 to 424.4 rpm, and the diameter of adjacent hearth rolls is changed at a pitch of 5 mm (between 120 and 130 mm). Within the range of As a conventional example, the diameter of each hearth roll is made the same, and the rotation speed is also made the same.

  Under the above conditions, in the conventional example, the amplitude of the bearing part of the hearth roll may be about 25 μm or more, and the result is that the surface of the steel plate is wrinkled. And the incidence rate of face-breaking wrinkles became 0.5%. On the other hand, in the example to which the present invention is applied, the amplitude of the bearing part of the hearth roll is 15 μm or less, and the occurrence rate of the surface crease is 0%.

It is sectional drawing which shows the structure which looked at the annealing furnace of embodiment of this invention from the side surface. It is sectional drawing which shows the structure which looked at the annealing furnace from the front. It is a characteristic view which shows the amplitude of this hearth roll when the rotation speed of all the hearth rolls is made the same. It is a characteristic view which shows the amplitude of this hearth roll when changing the rotation speed of adjacent hearth rolls.

Explanation of symbols

1 furnace shell, 2 heat insulating material, 3 furnace body, 4 ₁ to 4 ₆ hearth roll, 5 control unit

Claims (4)

  In an annealing furnace that anneals the steel sheet while transporting the steel sheet, a plurality of hearth rolls are rotatably supported on the same support, and the adjacent hearth rolls have different rotation speeds. A feature of suppressing vibration of a hearth roll.   The method for suppressing vibration of a hearth roll according to claim 1, wherein a difference in rotation speed between the adjacent hearth rolls is set to 3% or more.   The method for suppressing vibration of a hearth roll according to claim 1 or 2, wherein the diameter of the adjacent hearth rolls is adjusted so that the peripheral speeds of the outer peripheral surfaces of the adjacent hearth rolls are the same. In the annealing furnace of the steel plate that anneals the steel plate while conveying the steel plate,
A plurality of hearth rolls that are rotatably supported on the same support and convey the steel plate,
Control means for controlling the number of rotations of the hearth roll,
The said control means varies the rotation speed of what adjoins among these hearth rolls, The annealing furnace characterized by the above-mentioned.

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