JPS5911662B2 - How to prevent strip vibration - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing vibration of a strip and stably holding the strip on a predetermined threading line in a non-contact manner.

When conveying strips continuously in various processing lines for steel strips, it is often necessary to convey the strips over a fairly long distance without providing any contact type guides in order to ensure stable position control of the strips. be.

For example, in the hot-dip galvanizing process for steel strip, the strip leaving the pretreatment equipment is introduced at an angle into the hot-dip galvanizing bath and then passed through pot rolls placed in the bath. After changing the direction and pulling it out vertically onto the plating bath surface with the plating metal attached,
While the plated metal adhered to the strip surface is in a molten state, excess plated metal is wiped away by gas spray from a pair of gas wiping nozzles installed opposite to each other across the strip, and the desired coating weight is controlled. Ru.

After wiping, the strip is vertically moved upward until the surface plating layer is almost solidified, then turned around at the top roll position and sent to the next process. ) In addition, a zero spangle device, a galpaneer device, a cooling device, etc. may be arranged at the rear force portion of the wiping nozzle, facing the strip threading line, as necessary. In the hot-dip plating line described above, the strip must be vertically pulled up until the plated metal adhering to the strip surface solidifies, so the distance of the vertical plate passing section becomes quite long.

Therefore, vibration of the strip occurs in the direction of the lateral force, but contact support with rolls or the like is impossible because of the unsolidified metal surface. In particular, in recent years, high-speed sheet threading (15
Om/wLin or more), the solidification position of the deposited plating layer becomes higher and the vertical threading section becomes longer.

For example, the distance may exceed 30 m, and the vibrations are further amplified. Conventionally, the vibration width of the strip is predicted and care is taken to set the wiping nozzle outside the vibration width range in order to prevent the wiping nozzle from coming into contact with the strip.

This makes it difficult to bring the wiping nozzle close to the strip, resulting in a problem that the wiping ability, that is, the control range of the plating amount is narrow. In addition, because the distance between the wiping nozzle tip and the strip surface changes due to the vibration of the strip, it is not possible to obtain a uniform plating thickness in the longitudinal direction, width direction, and front and back sides of the strip, resulting in unevenness in the plating layer and noticeable product defects. There are also problems that degrade quality. Conveying the strip along a predetermined path is an extremely important factor not only in the melt plating line but also in other strip processing lines.

For example, when a strip is run continuously and heated to a desired temperature by spraying a gaseous substance in a furnace surrounding the strip, or when the strip is cooled at a desired cooling rate, the strip vibrates and If this changes, the heating or cooling of the strip will vary, making it impossible to obtain the desired properties, and vibrations of the strip will cause the strip to come into contact with other members, causing a problem in that the surface properties will be impaired. As described above, suppressing the vibration of the strip and stably transporting it along a predetermined line will bring great benefits in terms of quality improvement and uniformity as well as the operation of other equipment. It is strongly requested. Of course, in this case, a holding means such as a guide roll that comes into direct contact with the strip will damage the surface quality of the strip, so it goes without saying that a non-contact type strip holding means is preferable. Conventionally, non-contact holding means for the strip have been known that utilize the holding force of fluid sprayed onto the strip surface, and it has been found that applying static pressure to the strip is particularly effective.

A typical technique of this known non-contact type strip holding means is disclosed in Japanese Patent Laid-Open No. 50-67729. The contents shown in this Japanese Patent Application Laid-open No. 5067729 are specific to continuous galvanizing equipment, but the material is placed at any point on the vertical running part of the material provided with a squeezing device, such as a wiping nozzle, on both sides with the material sandwiched between them. Static pressure pads are installed symmetrically to ensure stable movement of the material passing near the expansion device and to obtain a uniform plating layer on the surface of the material. Further, the static pressure pad is formed from a box-shaped hollow body extending in the width direction of the strip, and a pair of gas jet ports for jetting fluid onto the material at mutually symmetrical angles are provided in the hollow body. A static pressure area is created between the strip surface and the cutting board formed in between, thereby holding the strip under static pressure. However, although it is recognized that the disclosure in JP-A-50-67729 provides important suggestions regarding non-contact support of strips in continuous galvanizing lines, it is difficult to apply this to actual equipment. Several issues remain to be resolved.

In other words, in order to achieve stable running of the strip, it is necessary to suppress the vibration of the strip, but how much static pressure should be applied to the strip in order to prevent vibration? It is necessary to specify the gas flow rate required to generate static pressure, as well as the positional relationship between the static pressure pad and other equipment, but the above-mentioned prior art does not mention any of these specific matters. . Therefore, it will be extremely difficult to apply static pressure pads to actual equipment unless the above points are clarified. The present inventors used a static pressure pad to suppress the vibration of the strip as much as possible in a strip processing line including a continuous melt plating line for strips, in order to ensure stable transfer of the strip. As a result of various research experiments on a strip vibration prevention method that can enhance the strip vibration prevention effect without increasing the gas flow rate, we have found that we utilize the gas flow flowing along the strip surface and apply it to the discharge flow of the static pressure pad. As a result, we have discovered a force method that improves the supporting force of the strip through a synergistic effect with static pressure and effectively prevents vibration of the strip.

That is, the object of the present invention is to provide a static pressure pad that can be used even if the gas flow rate or fluid pressure supplied to the static pressure pad is small (for example, even if the static pressure itself is insufficient to prevent vibration of the strip). The object of the present invention is to provide a method for preventing vibrations of a strip, which actually sufficiently suppresses vibrations and allows stable conveyance of the strip.

Another object of the present invention is to provide a method for preventing vibration of a strip, which can dramatically improve the supporting force of the strip by the static pressure pad and almost completely prevent the vibration of the strip (to about ±1 mm). It is in.

Another object of the present invention is that by stably transporting the nut strips, wiping nozzles, gas injection nozzles, etc., which were conventionally installed at a certain distance, can be installed very close to the nut strip surface, and the strip can be transferred evenly and efficiently. It is an object of the present invention to provide a method for preventing vibration of a strip which can be treated.

Furthermore, another object of the present invention is to apply it to various processing lines such as continuous molten plating lines and strip heat treatment lines, especially high-speed line threading, so that it is possible to control the amount of take-out, for example, the basis weight of molten Zn plating. The purpose of the present invention is to provide an effective method for preventing vibration of nutrips.

The power method of the present invention will be explained in detail below.

In the present invention, when arranging the static pressure pads facing each other across the threading line of the Nutrip, the static pressure pads are installed within a range where a fluid flow exists along the surface of the strip, and the static pressure pads are It confines fluid between the strip surfaces.

In other words, if a static pressure pad is installed at a position where there is a fluid flow on the strip surface so as to block this fluid flow, the flow released from one end of the static pressure pad to the outside will flow along the strip surface. Since it collides with the coming fluid flow and is confined between the Nutrip and the static pressure pad, the pressure based on the confinement is added to the original static pressure of the static pressure pad, and as the static pressure increases, the area of static pressure action also expands. As a result, the vibration of the Nutrip is effectively prevented.
The fluid flow on the strip surface to produce the containment effect is necessarily generated from the configuration of the strip processing equipment itself (e.g. jet flow from a wiping nozzle).
Of course, it is also possible to provide equipment that artificially creates this fluid flow.

It is necessary that the fluid flow maintains a flow velocity at the position of the static pressure pad that is sufficient to perform a containment effect, that is, a flow velocity that is at least equivalent to that of the fluid discharged from the static pressure pad. In practice, the strip processing line to which the force method of the present invention is applied is the position after the nutrips are pulled up from the plating bath in the vertical force direction and gas wiped by the wiping nozzle in the continuous melt plating line, and are applied to the strip surface. The above-mentioned containment effect can be expected if opposing static pressure pads are installed in the area where a gas flow exists due to the gas sprayed by the wiping nozzle.

In addition, when the strip passes through a furnace where the strip is heated or cooled, there is a gas flow along the surface of the strip that exits from the furnace due to the blowing of a gaseous substance in the furnace or due to a draft effect. A similar effect can be expected by installing a static pressure pad. next,
Although the present invention will be described based on embodiments shown in the drawings, the present invention is not limited to the illustrated examples, and may take any form as long as it falls within the technical idea of the present invention.

FIG. 1 explains the principle of the invention.

In the figure, 1 is a strip that runs vertically at a constant threading speed, 2 is a static pressure fluid pad placed close to the first surface of the strip, and 3 is a fluid flow rising along the first surface of the strip. show. The static pressure pad 2 is parallel to the strip 1 and applies pressure to the Nutrip surface within a certain range, and its structure is formed in the shape of a box connected to an appropriate fluid supply source as shown in the figure. , with fluid jets 4 oriented at angles facing each other, and a plate 5 substantially parallel to the strip 1 in the center. The fluid spout 4 is preferably formed as a null hole that is provided at a position leaving an edge plate 6 of a desired width from the periphery of the pad and surrounds the central plate 5, and the fluid is, for example, N2. An inert ganu such as ganu is used. In the above case, when fluid is ejected from the spout 4 of the static pressure pad 2, static pressure is generated in the space 5 between the nut trip 1 and the plate 5 of the static pressure pad 2, and this becomes a supporting force for the nut trip 1 and suppresses vibration. do.

This supporting force remains almost unchanged if the pressure or flow rate of the fluid supplied to the static pressure pad 2 is constant. However, as shown in FIG. 1, if there is a fluid flow 3 along the Nutrip 1 surface having at least the same flow velocity as the discharged fluid from the Hydrostatic pressure pad, the flow from the lower spout 4 of the Hydrostatic pressure pad 2 along the Nutrip 1. Then, the jet flow heading downward and the fluid flow 3 moving upward collide near the 4 points, and a phenomenon occurs in which the fluid from the pad is pushed back to the static pressure pad 2, where a containment effect by the fluid 3 occurs. The confinement effect of this fluid flow 3 results in an increase in the original static pressure of the static pressure pad 2 and an expansion of the static pressure acting area, as shown in the distribution of static pressure (1 tmAq) in Figure 1. It works to increase the supporting capacity through a synergistic effect. Further, in order to intentionally expand the area on which the static pressure acts, the effect will be improved if the edge plate 6 portion is lengthened. In addition,
The left force diagram in Figure 1 shows the static pressure distribution situation corresponding to the right force, where the dotted line 1 indicates the distribution when fluid flow 3 does not exist, and the solid line/opening indicates the distribution when fluid flow 3 exists. It can be seen that in the case of the mouth, the static pressure area increases at the same time as the static pressure increases.

Figure 2 is a diagram to conceptually explain the fluid confinement effect.The vertical axis shows the supporting force of the fluid (the supporting force of the strip at the static pressure pad position), and the horizontal axis shows the flow velocity of fluid flow 3. , the fluid supply pressure to the static pressure pad is constant.

In the figure, the dashed line a shows the level of supporting force in the absence of the fluid flow 3, and the solid line b shows the supporting force that changes depending on the flow rate of the fluid flow 3. As is clear from this, the supporting force increases as the flow velocity increases (particularly at a flow velocity of 10 m/sec or more), and is approximately 2 to 2
．． However, it can be seen that when the flow velocity exceeds a certain value, the containment effect becomes saturated and the supporting capacity does not improve.
Therefore, in the force method of the present invention, a static pressure pad is placed in an area where the fluid flow on the strip surface has a flow velocity of a certain level or more, and the supporting force is improved by the confinement effect of the fluid flow.

According to the present invention, when the flow rate is the same as before, the supporting force of the static pressure pad can be increased more than before, and the vibration prevention effect can be enhanced. The flow rate can be significantly reduced, which is extremely advantageous in terms of energy conservation. Various specific conditions for fully exhibiting the fluid containment effect will be described below.

The important factors that influence the containment effect are the velocity of the fluid flow along the strip surface (in this case, the velocity near point A in Figure 1), the fluid force and flow rate supplied to the static pressure pad, but Other considerations include the distance between the strip and the static pressure pad, the shape of the pad, etc. If the fluid flow velocity is too low, the fluid cannot be contained within the static pressure pad, and if the fluid flow velocity is too high, more fluid will escape to the opposite side of the static pressure pad, which is undesirable. Regarding the fluid pressure and flow rate supplied to the static pressure pad, if the pressure and flow rate are too low, the absolute static pressure will be insufficient and the containment effect will be weakened, and if the pressure and flow rate are too high, energy saving and equipment capacity will be affected. becomes disadvantageous. The velocity of the fluid flow, the fluid pressure of the static pressure pad, and the flow rate are closely related and cannot be determined independently. An example of its implementation specifications is shown in FIG. According to FIG. 3, the required static pressure to the static pressure pad is set within a suitable range from the viewpoint of equipment capacity, for example between the pot roll and top roll of the galvanic line, for example h
= 15 mm and 20 to 200 mmAq (preferably 40
~607 nmAq), the flow velocity of the discharged fluid flow is preferably in the range of 10 to 20 m/s, and under this condition, the fluid supporting force from the original pad is 2 to 2. Increased by 5 times. This difference is actually the difference in choosing a fluid supply blower: whether you can use a normal low pressure (discharge pressure 1200m1Aq) blower, or whether you need to install a high pressure blower (such as the Roots blower), which has high equipment costs and running costs. becomes. The reason is that according to the embodiment shown in Fig. 3, when h-15 is used, the required blower discharge pressure is 950 m7! It becomes LAq. This figure does not include margin factors, which are naturally taken into account when designing the actual machine, and a low-pressure blower cannot withstand fluctuations in the required static pressure. Here, the effect of the present invention in that it is possible to increase the fluid supporting force without increasing the flow rate from the static pressure pad is highly appreciated. Within such a range of conditions, various suitable ranges can be selected depending on the dimension of the pad, the installation position, and the degree of vibration prevention required. still,
In FIG. 3, the implementation specifications are as follows. Optimal nozzle specifications t=2m1! L, θ=30~45 Necessary static pressure (M
mAq) Pn+(2.7~4)×h nozzle flow rate (
m/S) U+1.63 (Pn-h) 1/2 nozzle shape (a=M7n) Required flow rate assuming b/a=0.3 (Niln) Q=3.12×10-4×o
×3 Required blower discharge pressure (MmAq) PO-012×U
2+600+h Here, the distance h between the strip and the nozzle is determined by the vibration state of the strip. Next, embodiments of the present invention will be described.

Figure 4 shows an example in which the force method of the present invention is applied to a continuous melt plating device for nutrips, in which the strip 11 is immersed in a melt plating bath and then pulled up in the vertical force direction, and the plating metal attached to the strip surface is removed. At the position where the metal is in a molten state, gas is sprayed by wiping nozzles 14 installed opposite to each other with the strip 11 interposed therebetween to wipe away excess metal. Since the wiping nozzle 14 is a dynamic pressure nozzle and injects gas almost perpendicularly to the surface of the strip 11,
This jetted gas flow collides with the strip surface and flows in two directions, up and down. Gas flow 1 toward the upper blade of Nutrip 11
Nutrip 11 within the range where 3 maintains a sufficient flow rate.
If a pair of static pressure pads 12 are installed symmetrically across the strip surface, the Ganu flow 13 rising along the strip surface will further increase the effect of confining the fluid within the static pressure pads 12. This further improves the supporting force within the nut 12 and, as a result, suppresses the vibration of the nut trip. If the vibration of the strip is suppressed, it becomes possible to bring the wiping nozzle 14 closer to the strip 11, and the distance between the wiping nozzle and the strip hardly changes, so that uniformity of the basis weight can be achieved and a high-quality plated product can be obtained. It will be done.
Note that the flow velocity of the gas flow 13 along the nut trip surface generated by being injected from the wiping nozzle 14, which is a dynamic pressure nozzle, is faster as it approaches the spraying position on the nut trip surface, and decreases as the distance increases. . Therefore, if the distance between the wiping nozzle 14 and the static pressure pad 12 is too large, the flow velocity of the Ganu flow 13 will be slowed down, and the above-mentioned fluid containment effect cannot be expected. Considering these points and the pressure normally adopted as the dynamic pressure of the wiping nozzle, the distance between the wiping nozzle and the static pressure pad is approximately 15
In order to achieve the object of the present invention, it is desirable that the distance be within 0.00 mm, preferably about 100 to 500 mm. Further, in the example shown in FIG. 5, a static pressure pad 22 is arranged on the outlet side of a furnace 23 such as a cooling device installed so as to surround the vertically running portion of the nutrip 21.

Even in such a furnace 23, when an appropriate gas fluid is blown onto the surface of the strip 21 in the furnace, an upward gas flow is generated along the surface of the strip 21 at the exit side of the furnace 23 as shown by the arrow 24, and this It functions to confine the fluid flowing downward from the hydrostatic pad 22 to the hydrostatic pad front surface 25, thereby increasing the static pressure on the hydrostatic pad front surface 25. As a result, the strip 21 is held with a high supporting force at the front surface 25 of the static pressure pad, and its vibration is suppressed, so the traveling path of the strip 21 becomes stable, and the gas fluid spraying device etc. in the furnace is Since it can be placed as close to the strip as possible, efficient cooling can be achieved. In addition, in the past, all equipment was arranged by predicting the vibration of the strip to some extent, but with the present invention, the vibration of the strip can be almost ignored, so even the smallest scale equipment with no waste is sufficient to achieve the purpose. can. Furthermore, FIG. 6 shows another embodiment of the present invention, in which a static pressure pad 32 without a lower fluid jet port is arranged on the exit side of a wiping nozzle 33 similar to that in FIG. 4. It is something.

Such a static pressure pad 32 alone cannot provide a significant static pressure, but in the case of FIG. 6, there is a fluid flow (arrow 34) from the wiping nozzle 33 along the strip 31, so this gas flow is static At the pressure pad front 5,
It can be expected to exhibit a containment effect and provide static pressure support. In this example, the static pressure pad 32 is removed from the wiping nozzle 33 as much as possible.
It is preferable to arrange it close to the outlet side of the static pressure pad 32, and the amount of fluid supplied to the static pressure pad 32 can be greatly reduced.

The above example shows an embodiment in which the present invention is applied to a melting plating line and a gas furnace equipped with a hydrodynamic pressure nozzle. It goes without saying that the present invention can be applied as long as there is a predictable level of fluid flow.

Furthermore, the present invention is not limited to the fluid flow produced as a result of spraying the gas fluid onto the strip surface, but may also utilize a flow produced by other factors (blowers, drafts, etc.).

[Brief explanation of the drawing]

Fig. 1 is a schematic diagram for explaining the principle of the force method of the present invention and static pressure distribution, Fig. 2 is a diagram showing the effects of the present invention, and Fig. 3 A shows static pressure examples of practical specifications of the present invention. A side view and a front view of the pad, Fig. 4 is a schematic diagram when the present invention is applied to a strip melting plating line, Fig. 5 is a schematic diagram when the present invention is applied to a processing line using a gas furnace, and Fig. 6 is a schematic diagram when the present invention is applied to a processing line using a gas furnace. FIG. 5 is a schematic diagram showing another example of FIG. 4; 1, 11, 21, 31... Strip, 2, 1
2, 22, 32... Static pressure pad, 3, 13, 2
4,34...Fluid flow, 14,33...
・Wiping nozzle, 23... Gas furnace.

Claims (1)

[Scope of Claims] 1. In a strip threading line, static pressure pads are arranged opposite to each other across the strip, and at least the fluid discharged from the static pressure pads arranged on the opposite surface of the strip is supplied from the static pressure pads. 1. A method for preventing vibration of a strip, characterized in that another fluid having a flow velocity equivalent to that of the discharged fluid is caused to flow counter-currently so as to block the discharged fluid. 2. The method of claim 1, wherein the velocity of the fluid stream on the strip surface near the location of the hydrostatic pad is at least 10 m/sec.