JPS61281825A - Floater for supporting strip - Google Patents

Abstract

PURPOSE:To efficiently float a strip by providing a floater having an opening for spouting a fluid in the oblique upward direction at the front and the rear end part in the traveling direction of the strip of the pressure receiving surface of the main body immediately below the strip, specifying the width of the opening and reducing the unused flow of the spouted gas. CONSTITUTION:A floater 11 has a slit nozzle 12a which is opened on the surface opposed to the lower surface of a traveling strip 1 and used as a nozzle for a fluid. The nozzle 12a is a narrow slit which is extended in the widthwise direction of the strip 1 and respectively provided to the front and the rear end in the traveling direction of the strip 1. Both nozzles are inclined to the lower surface of the strip 1 so that the gas spouting directions are faced to each other. The upper smooth pressure receiving surface 16 is supported by the static pressure produced by the gas spouted into the clearance under the strip 1 and the strip is floated above the floater 11 and traveled. The width of the opening of the nozzle 12a is enlarged at the central part in comparison with both ends in the widthwise direction of the strip 1. Consequently, the amt. of the fluid escaping to the outside of both end parts in the widthwise direction of the strip 1 and the spouted fluid can be effectively utilized.

Description

[Detailed Description of the Invention] Industrial Application Fields The present invention relates to a floater for strips that is attached to a continuous annealing furnace for metal strips such as steel strips and supports the strips in a non-contact manner during threading. Regarding (Prior art) Cold rolled steel sheets
As shown in the figure, a strip L of cold-rolled steel sheet is fed out to a payoff reel J (not shown), passes through a cleaning tank, roots R (not shown), etc., and is supplied to a continuous annealing furnace. In this continuous annealing furnace, a large number of ferret rolls 2 are provided above and below, and the strip 1 is wound around these ferret and e-rolls 2.

As it moves up and down in the furnace, it undergoes the necessary heating and cooling depending on the mechanical properties required for the product, and is given the necessary mechanical properties such as yield strength, tensile strength, and good deep drawability at room temperature. . In addition.

The interior of the continuous annealing furnace is filled with reducing gas such as hydrogen nitride gas to prevent surface oxidation of the IJ tube.

Strip 1 is typically 650-900 in heating zone A.
It is heated by the radiant tube 3 to about ℃. After that, it is heated uniformly for several tens of seconds in a soaking zone B, and then heated to 400 degrees by a gas jet at a cooling rate of 3 to 200 degrees per second in a rapid cooling zone C.
It is quenched to about 0.degree. C., then subjected to an overaging treatment at about 400.degree. C. for about 2 minutes in an overaging zone, and finally quenched to room temperature by a gas jet in a final quenching zone E.

By the way, in such a continuous annealing furnace, the overaging zone requires a long residence time of about 2 minutes, so in a large continuous annealing furnace, the length of the overaging zone can be as long as 100 meters or more. Therefore, the continuous annealing furnace as a whole is very long, over 150 meters. If this overaging zone can be shortened, it is expected that a continuous annealing furnace can be manufactured in a shorter length and the construction cost of the equipment can be reduced. As a specific means for this, it has been found that the length of the over-aged zone can be shortened by changing the material of the strip l and increasing its heating temperature compared to the conventional process.

However, when realizing such a furnace, if a high-temperature strip is brought into contact with the rolls, the strength of the strip is reduced, resulting in uneven contact with the cold rolls and adhesion of forces in the rolling oil. Thermal deformation of the strip due to contact with the rolled roll surface becomes a problem in threading.

Also, in the conventional method, the sea urchin strip is run vertically.

If the strip is run, the high temperature causes a creep phenomenon due to the strip's own weight and the width becomes narrow. Therefore, it is necessary to run the strip horizontally and stably run as long as possible without contacting the rolls.

In order to thread the material over a long distance in the horizontal direction without stripping, a floater has been developed that supports the IJ knob in a non-contact manner, and this floater is used, for example, in color coating lines. has been done.

As shown in FIG. 7, which conceptually represents a conventional floater, and FIG. 8, which shows a cross-sectional structure of the floater, a plurality of floaters 11 are provided below the running strip l in the direction of one strip (FIG. 7). They are arranged across the middle, left and right directions. Each floater 11 has narrow slit nozzles 12t at both front and rear ends of the strip l in the threading direction, and these slit nozzles 12 diagonally face the strip l. The gas in the chamber 5, which is supplied from the slit nozzles 2 to the gas supply duct 14, is ejected into opposing channels. This ejected gas is strip l
and 70-ta 11 I! Pushed into Iis,
Gas pressure is generated between the floater 11 and the pressure receiving surface 16 on the upper surface of the floater 11, causing the strip 1 to float and pass through the strip. Note that as the ejected gas, the same kind of gas as the atmospheric gas in the furnace is generally used, such as hydrogen nitride.

<Problems to be Solved by the Invention> Looking at the pressure distribution in the width direction of the IJ tube 10 between the strip l and the pressure receiving surface 16 in the conventional floater 11 described above, the pressure in the center portion of the strip 10 in the width direction is The pressure is almost constant, but as you approach the end, the pressure suddenly drops from a certain point. In Figure 9, the width is Ll + I4 + L
The pressure distribution in the width direction of the strip 1, which is B, is shown. Strip 1 shown in the same figure has a width of Lt+l4tLs
In this case, the measured pressure at the center is the same, but the pressure suddenly decreases from a distance of 4 + 4 + 63 from each end, and the pressure at the end becomes the same as the outside air. ing.

In this case, the distance between Zl ez and ez is
They are exactly the same. The position at which the pressure exerted by the tab V and the strip L begins to decrease is constant regardless of the width of the strip L or the magnitude of the pressure that the IJ strip is subjected to at its central portion. Therefore, in narrow strips, there is a lot of fluid loss −Ls, Lx,
The average pressure received by LtQ is * P3 * P2 + ding p/J%.

On the other hand, the slotted rod 1z in the conventional floater 11
As shown in FIG. 10(a), the gas ejected from the strip 1 is at the center in the width direction of the strip 1.

Most of #-1 is a flow a that reverses in the longitudinal direction of the strip 1, whereas at both ends of the strip, most of it flows between the strip l and the receiving pressure [16] and does not reverse. Flow b escapes to the outside in the width direction of strip l. FIG. 10(b) shows the flow velocities of these flows a and b with respect to the X-X axis and Y-Y@I. Here, (i) The point at which the flow b escaping to the outside in the width direction of the IJ tube begins to increase almost coincides with the point at which the pressure applied to the strip l begins to decrease. therefore.

The only gas flow that generates an effective pressure to levitate the strip 1 is the flow a in which the jetted gas from the slit 12 is reversed in the longitudinal direction of the strip 1, and the flow b outward in the width direction of the strip 10 is wasteful. It is a flow.

For the above reasons, F. With the conventional floater 11, there is a problem that when the width of the strip 1 is changed based on the entire flow rate of gas ejected from the slit 12, the flying height of the narrow strip 1 becomes lower. It's hot. ! In figure 11.

The relationship between the width of the IJ tube l and the flying height is shown when the flying height is 100 when the width of the stripe is 100. #1, where the width of the strip l is narrower, has a smaller flying height.

A narrow strip 1 is placed on a conventional floater 11 by
When running, it is necessary to increase the flow rate of gas ejected from the friend slit 12, where the strip 1 does not float too much and may come into contact with the floater 11. It was getting bigger.

In view of the above circumstances, an object of the present invention is to provide a floater for supporting a strip that can efficiently levitate the strip by eliminating wasteful flow of gas ejected from the gas outlet.

<Rounding means for solving the problems> The configuration of the present invention that achieves all of the above objects is that a pressure receiving surface facing the strip is formed directly below the strip, and a pressure receiving surface facing the strip is formed along the main body and the strip along the threading direction of the strip. (9) Openings are made at both front and rear ends of the pressure receiving surface along the width direction of the strip plate, and fluid is ejected obliquely upward toward the center of the pressure receiving surface to create a space between the strip plate and the pressure receiving surface. In a floater for supporting a strip plate, the width of the opening of the fluid outlet in the passing direction of the strip plate is set at both ends in the width direction of the strip plate. It is characterized by having a wider center area.

For Kusaku Fluid t ejects between the strip plate and the pressure receiving surface.

Since the amount of fluid is larger at the central portion of the strip than at both ends in the width direction, it is possible to effectively utilize the ejected fluid by reducing the amount of fluid escaping to the outside of both ends of the strip in the width direction.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view of a floater for supporting a strip according to an embodiment, and FIG. 2 (ω, CO) is a sectional view thereof. As shown in these drawings, the floater 11 has a slit nozzle 12a'i, which serves as a fluid ejection port, and is open on a surface opposite to the lower surface of the running strip 1. The slit nozzles 12a have a narrow slit shape extending in the width direction of the strip l, and are provided at both front and rear ends of the floater 11 in the running direction of the strip 1. The sections facing each other are formed obliquely with respect to the lower surface of the strike IJ tab 1. The inside of the floater 11 is a chamber 13 filled with pressurized gas such as hydrogen nitride gas.
It squirts out towards the bottom surface of 1 tube.

The upper surface of the ceiling of the chamber 13 is a smooth pressure-receiving surface 16, and this pressure-receiving surface 16 receives the static pressure generated by the ejected gas ejected into the gap 15 below the IJ tube 1. The stripe is supported by the static pressure of the floater 11 and travels floating above the floater 11.

The slit nozzle 12a of this embodiment has an opening width (slit) of
The width of the IJ tube l in the running direction is set to be wider at the center than at both ends of the strip l in the width direction, and gradually narrows from the center to both ends. In addition, Fig. 2 (at
2 shows the cross-sectional structure of the center portion of the floater 11, and FIG. 2 (0)) shows the cross-sectional structure of both ends.

In general, in a floater that floats and supports a strip by the static pressure of ejected gas, the floating blade F that the IJ tube receives on the pressure receiving surface is expressed by the following equation.

tF=C7v”T(1+cos#)-AF
: Levitating blade (-) C: Constant determined by the shape of the fluid jet port, the shape of the 70-ta, the size of the strip, etc. r: Specific weight of the ejected gas (Kf) g: Gravitational acceleration (m/5-) V Fluid ejection speed from the two-fluid ejection port (''/s) t: Gas ejection width of the fluid ejection port (m) h: Flying height (m) θ: Inclination angle of the fluid ejection port (0) Pressure-receiving area of the A Ni lip (-) According to a divine coincidence, at the central part in the width direction of the strip l, a floating edge close to the above theoretical formula can be obtained, but at both ends, floating edges according to the theoretical formula cannot be obtained. As described in the prior art section, (i) At both ends of the IJ tube l, the ejected gas does not become a flow a that reverses in the longitudinal direction of the strip l, but forms a flow b that escapes to the outside in the width direction of the strip l. This is because it becomes

On the other hand, the ejection velocity vt of the fluid from the slit nozzle 12a
--When the jet is kept at the same height, the width t of the spout and the floating height h of the strip are in a proportional relationship.

Therefore, the width of the slit nozzle 12a at the center in the width direction of the strip l, where a floating blade that is relatively consistent with the above theoretical formula can be obtained, is increased, and the slit nozzles at both ends, where there is a lot of loss and a floating blade that is not as expected in theory, are widened. By narrowing the width of 12a, in particular, the wasteful flow bt- can be reduced and the ejected gas can be used effectively. In addition, if the ejection speed of the rainbow ejected gas is the same, even if the width of the strip l is changed, the same level of flying height can be obtained. It's getting bigger.

FIG. 3 shows IJlsLl in the floater 11 of this embodiment.
1 shows the pressure distribution across the width of a strip l having a width of l; In addition, assuming the same gas ejection speed as when using the conventional floater l1t (see Fig. 9), the maximum pressure r of the conventional L3
Expressed as ioo. As shown in the figure, the average pressure in the floater 11 of this embodiment is 20 to 20% higher than that of the conventional one.
It is about 25% the same as above, and the difference in the maximum pressure in the strip L having a width of Lt and Ia has almost disappeared.

Although the slit nozzle 12a of the above embodiment has the opening width changed linearly, it may also be changed based on a certain function or in steps. FIG. 4 shows an embodiment in which the opening width at the center of the slit nozzle 12b is widened in steps at both ends.

Furthermore, in all of the above embodiments, the nozzle for ejecting the rainbow gas from the floater 11 has a slit shape extending in the width direction of the strip l.

This nozzle is also constructed as a multi-circular hole nozzle in which a large number of circular holes are arranged in a row in the width direction of the strip l.

In this case, the present invention can be implemented by increasing the diameter of the circular hole in the central portion. FIG. 5 shows an embodiment in which the diameter of the circular hole of the multi-circular nozzle 12c is gradually reduced by l from the central portion in the width direction of the strip l toward both end faces.

<Effects of the Invention> According to the present invention, the opening width of the fluid jet port facing the lower surface of the running strip in the running direction of the strip is made larger at the central portion than at both ends in the width direction of the strip. By widening the gap, the wasteful flow of the ejected gas can be reduced and the ejected gas can be used more efficiently. If the same flow rate of ejected gas is used for this, a larger floating blade can be obtained compared to the conventional one, and
The effect is that the difference in flying height due to the difference in the width of the strips is almost eliminated. The floater for supporting strips of the present invention can be used not only in continuous annealing lines for cold-rolled steel sheets, but also in continuous galvanizing lines, stainless steel plate annealing lines, continuous electrolytic cleaning lines, colored iron plate coating lines, and continuous heat treatment of copper, aluminum, etc. It can be widely applied to equipment such as furnaces and even paper processing equipment.

[Brief explanation of the drawing]

Fig. 1 is an external perspective view of a floater according to an embodiment of the present invention, Figs. 2(a) and (b) are sectional views thereof, and Fig. 3 is an explanatory diagram showing the pressure distribution due to the floater. , FIG. 4 and FIG. 5 are perspective views showing the external appearance of a floater according to another embodiment of the invention, FIG. 6 is a conceptual diagram of a conventional continuous annealing furnace, and FIG. 7 is an external appearance of a floater according to the prior art. FIG. FIG. 8 is a sectional view thereof, FIG. 9 is an explanatory diagram showing the pressure distribution by a conventional floater, and FIG. 10(a) is an illustration. An explanatory diagram showing the flow of fluid by a conventional floater. FIG. 10(b) is an explanatory diagram showing the flow velocity with respect to the X-X axis and the Y-Y axis, and FIG. 11 is a graph showing the relationship between the running strip and the flying height in a conventional floater. Inside the drawing. l is strip. 11 is a 70-hole nozzle, 12a and 12b are slit nozzles, and 12c is a multi-hole nozzle. 16 is a pressure receiving surface.

Claims (1)

[Claims] A main body having a pressure receiving surface opposite to the strip plate formed directly below the strip plate, and openings along the width direction of the strip plate at both front and rear ends of the pressure receiving surface along the threading direction of the strip plate. and a set of fluid ejection ports that eject fluid obliquely upward toward the center of the pressure-receiving surface to generate static pressure of the fluid between the strip and the pressure-receiving surface. 1. A floater for supporting a strip plate, characterized in that the opening width of the fluid ejection port in the passing direction of the strip plate is set wider at the center portion than at both ends in the width direction of the strip plate.