JPH05201594A - Control method for floating transport of band body - Google Patents

Abstract

PURPOSE:To maintain floating of a strip securely by providing the same number of three or more of slits on each side of a pad in feeding direction, and selecting the slits according to plate width to control a gas for floating the strip. CONSTITUTION:Slits S1 and S2 are provided on both sides of a strip 12 of a pad 10 in feeding direction, air is fed to the pad 10 by a blower 11, and air is blown off from the slits to float the strip 12 by static pressure generated between the strip 12 and the pad 10. To change over the slits, for narrow strip 12-2, for example, valves V2 and V3 are opened and the slits S2 and S3 are used and, for wide strips 12-1, valves V1 and V2 are opened and the slits S1 and S2 are used. Also, when the plate width is changed from wide to narrow, the slits are changed over before an welding point reaches the inlet of the pad 10 while, when it is changed from narrow to wide, the slits are changed over after the welding point passes through the pad.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of controlling floating transportation of a strip.

[0002]

2. Description of the Related Art A fluid is sprayed on the lower surface of a strip,
In a strip levitation device for levitationally supporting a strip, a strip levitation device in which a substantially upright side plate is installed on the side of a strip moving line in parallel to the strip moving direction is proposed in, for example, JP-A-63-176435. ing.

[0003] For example, stainless steel strip is annealed after cold rolling, and is a vertical furnace having at least two passes, which has a turning portion for turning the strip in the sheet passing direction. A continuous annealing furnace for strips is disclosed, for example, in Japanese Patent Laid-Open No. 2-61009, in which a tension generator is installed and a guide device for guiding a strip passing through a gas jet in a non-contact manner is installed in the turning part. There is a proposal to make the front half of the furnace a heating zone and then the soaking zone in order from the top, and the latter half the cooling zone.

[0004]

DISCLOSURE OF THE INVENTION The present invention provides a method for ensuring and controlling the levitation force of a belt-like material in a device for blowing gas from a pad (chamber) to support the belt-like material from the pad surface in a non-contact manner. Is provided.

[0005]

According to the present invention, when a levitation fluid is fed to a pad having three or more slits on one side and the same number of slits on both sides in the width direction to convey the zonal body in a non-contact manner. Depending on the width, the same number of slits of two or more on one side and four or more on both sides corresponding to the end portion in the width direction of the strip is automatically selected from the group of slits, and the levitation fluid is fed in to form A method for controlling the levitation conveyance of a belt-shaped body, characterized by levitating an object.

The present invention will be described in detail below. The present invention is a non-contact device for a strip-shaped object (hereinafter referred to as a strip), which is composed of a pad (chamber) having a plurality of slits or holes, a blower and a pipe for feeding the gas to the pad, and supplies the gas according to the width of the strip. The levitation force of the strip is secured by automatically switching the blowing slit.

FIG. 1 shows a strip 10 in a pad 10
Is conveyed in the direction of the arrow, the pad 10 controls the control valve V ₁ ,
The desired transformed gas is pumped from the blower 11 via V ₂ and V ₃ .

FIG. 2 is a developed view of the pad 10 of FIG.
The pad 10 is provided with slits S _{1 to} S _{3 on} both sides of the strip 12 in the transport direction. When the gas is blown into the pad by the blower and the gas is blown out from the slits (S _{1 to} S ₃ ), the strip floats due to the static pressure generated between the strip and the pad.

According to an experiment, the static pressure is generated, for example, as shown in FIG. 3, when the gas is ejected from the slits S ₂ and S _{3 at the same} flow rate and the gas supply to S ₁ is stopped, the slit S ₃ is generated. Static pressure Pc (kg / m ² ) and slit S ₂ ,
The static pressure Pcs during S ₃ is expressed by the following equations.

Pc = C ₁ ρU ² (t / h) ⁿ (1) where Pc: static pressure (kg / m ² ) ρ: gas density (kg · sec ² / m ⁴ ) U: blown out from slit Flow velocity (m / sec) C ₁ : Constant t: Width of slit (m) h: Distance between strip and pad (m) n: Index (about 1.5 to 2.0) Pcs = 3/4 Pc ( 2) On the other hand, the relationship between the load applied to the pad and the static pressure is given by the following equation. Pcm = C ₂ T / L (3) where Pcm: average static pressure (kg / m ² ) C ₂ : constant (m ⁻¹ ) T: load applied to pad (kg) L: width between outer slits ( m) Pcm = (LcPc + 2LsPcs) / (Lc + 2Ls) (4) where Lc: width between slits S ₃ (m) Ls: width between slits S ₂ and S ₃ (m) From equations (1) to (4) , The following equation is obtained. T = C ₄ LρU ² (t / h) ⁿ (5) where C ₄ is a constant, that is, when the flying height h and the gas flow velocity U are the same, the larger the outer slit width L is, the larger the load T is. I know that I can bear it. Therefore, L is preferably large, but when the plate width is narrow, for example, when the edge of the strip is between the slits S ₂ and S ₃ in FIG. 3, the static pressure as shown in FIG. 3 does not occur. It is not possible to secure levitation force. Therefore, in order to efficiently obtain the levitation force, it is necessary to select the slit according to the plate width.

Switching of the slits is performed as follows.
In the case of the narrow strip in FIG. 2, the valves V ₂ and V ₃ are opened and the slits S ₂ and S ₃ are used. On the other hand, in the case of a wide strip, the valves V ₁ and V ₂ are opened and the slits S ₁ and S ₂ are used. Further, in the case of the wide strip, the levitation force can be secured even if the flow velocity, that is, the air volume can be increased even with the S ₂ and S ₃ slits. However, when the narrow strip comes when the S ₁ and S ₂ slits are used, the static pressure does not rise as described above, and the levitation force is significantly reduced. Therefore, plate width change point (welded part)
Then, if the slit is selected as shown below, the levitation force can be stably secured. (1) When the plate width changes from wide to narrow, the slit is changed from wide to narrow before the welding point reaches the pad entrance. (2) When the plate width changes from narrow to wide, the slit is switched from narrow to wide after the welding point passes the pad.

The valves V _{1 to} V ₃ shown in FIG. 2 may take several tens of seconds from full opening to full closing or from full closing to full opening. Therefore, as illustrated in FIG. 4, when the strip transitions from the wide width to the narrow width, the welding point is Lm from the pad inlet.
When it comes to the front (point P ₁ ), the valve V ₁ shown in FIG. 5 is closed, and at the same time, V ₃ is opened. On the other hand, if the strip is wide Semakara wider migration, weld closing the valve V ₃ reaches the outlet (P ₂ points) of the pad, opening the V ₁ simultaneously. As for the plate width, the actual measurement value at the point P ₀ in FIG. 4 or the nominal width while passing through the point P ₀ is monitored, and it is determined whether slit switching is necessary or not based on the change in the plate width. FIG. 6 shows an application example of the present invention. Slits S ₁ , S ₂ and S ₃ are provided on both sides in the width direction of the pad 10, and control valves V ₁ , V ₂ and V ₃ which are electrically connected to the slits are provided. A strip width signal (passing point P ₀ ) 15, a welding point signal (strip joint) 16 and a strip speed 17 are input to the slit selection control device 14.

A valve opening signal from a valve opening detector 13 provided in the control valve is input to the slit selection control device 14.
In this example, when the strip changes from the wide width to the narrow width, the valve V ₁ is closed and the valve V ₃ is opened at the welding point P ₁ . Further, when shifting from the narrow width to the wide width, the valve V ₃ was closed and the valve V ₁ was opened at the welding point P ₂ . The valve V ₂ is open all the time. By this valve control, a sufficient levitation force was maintained when the strip was passed through the pad.

[0014]

According to the present invention, the pad is provided with the same number of slits of three or more on one side on both sides in the width direction to control the levitation gas. Therefore, when the width of the strip changes or the width of the strip changes,
The floating of the strip can be reliably maintained.

[Brief description of drawings]

FIG. 1 is a partial explanatory diagram of the present invention.

FIG. 2 is a development view of FIG.

FIG. 3 is an explanatory view of the operation of the present invention.

FIG. 4 is an explanatory diagram of an example of the present invention.

FIG. 5 is a chart of valve opening and time.

FIG. 6 is an explanatory diagram of an application example of the present invention.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Norio Hayashi 46-59, Nakahara, Tobata-ku, Kitakyushu City Nippon Steel Corporation Machinery & Plant Division

Claims (1)

[Claims] 1. When feeding a levitation fluid to a pad having three or more slits on one side and having the same number of slits on both sides in the width direction to convey the strip-shaped body in a non-contact manner, the slits are formed according to the width of the strip-shaped body. A strip-shaped object is levitated by automatically selecting the same number of slits of two or more on one side and four or more on both sides corresponding to the end portion in the width direction of the strip from the group and sending the levitation fluid. Control method for floating conveyance of a strip.