DE7119126U - DEVICE FOR CONTINUOUS CONTROL OF THE UNIFORMITY OF THE ZINC PLATE OF A STEEL SHEET - Google Patents

Description

PATENT LAWYERS

7 STUTTGART 1. ... 1.2 .. ... May ... .1.971

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DR.-1NG. WOLFh, h. BAKIELb, phone, (07ii) »i3ioond» ms

DR. BRANDES, DR.-ING. HELD telex. 072312

DIPL.-PHYS. WOLPP - 1 -

Our reference: 122 956/8417 rsi

Italsider SpA, Genoa, Via Corsica No. 4 (Italy)

Device for continuously controlling the uniformity of the zinc coating on a steel sheet

7118128 23rd n.71

«Μ Ο«

The invention relates to an apparatus for continuously controlling the uniformity of the zinc coating on sheet steel.

It is known that cold-rolled steel sheet is galvanized by immersing the sheet in a bath of molten zinc which is maintained at a suitable temperature. According to the current state of the art, the control of the zinc layer thickness required for this is mainly achieved in two ways. Either the zinc sheet coming out of the bath is brought between two metal rollers known as zinc application rollers; by adjusting the speed, the mutual pressure and the depth of immersion of the rollers in the bath, one can control the thickness and consequently the weight of the zinc coating. This method has the advantage that it is possible to galvanize workpieces, the size of which is due to the heat capacity of the furnace, at low speed; but the procedure is fraught with a few drawbacks , which can be summarized as follows:

- Low speed over a certain thickness r ^ range, because the weight of the job is hard to

check. The consequence of this is a lower power capacity. "

- Rigid production planning because , due to the wear and tear of the rollers, one has to switch from wide band production to narrow band production and from thin band to thick band.

- Defective surface quality of the zinc application because of the slag dragged along by the zinc application rollers.

- The impossibility of producing products with a zinc coating weight below certain values.

- Bone distribution of the order weight.

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- Wear of the zinc application rollers, which is at least have to be replaced weekly, for which the whole system has to be shut down for about four hours.

- Great experience and careful working methods of the Application rollers working personnel.

In the second method for controlling the zinc plating thickness of two thin steam or air jets are provided with controlled temperature and pressure / v against the two surfaces of the from. Zinc bath coming steel strip to be straightened. They are usually referred to λ as air or steam flat jet / fee. The flat fluid jet directed against the surface of the steel strip coming out of the zinc bath stops the excess zinc that is dragged along by the Bald. The weight of the zinc application is controlled by the control of the following parameters:

a) - pressure of the fluid /

b) - Position of the flat rays, that is, their height above the

Bath level, distance of the nozzles from the steel belt and angle of inclination of the flat jet of fluid to the belt;

c) - geometry of the flat rays, that is, their shape

and thickness from one end to the other of the steel belt; the thickness must be approximately constant at the ends for every band width and thinnest in the middle of the band.

The features of this second already known method have proven to be a good addition to the first method, because in the case of the Plnldf Iachs 1 *? * Ffh1 ^ n the belt speed cannot be reduced below a constant minimum speed; however, this disadvantage can be remedied by increasing the heating furnace capacity. On the other hand, the following can be regarded as advantages:

- Increase the galvanizing speed until it is reached the maximum furnace power;

- savings in zinc consumption; the better evenness of the order results in up to about 10% less Zinc consumption;

- More flexible production planning options thanks to the elimination of the application rollers, which are susceptible to wear;

- Significant improvement in the surface quality, which is no longer affected by the slag

C - The possibility of producing material with a zinc coating that is less difficult than when it is applied by means of coating wholesalers;

- Lower maintenance costs, since there is no need to periodically replace the applicator rollers at short intervals;

- Easier way of working and fewer staff required.

But even this second method, the original zinc application thickness control, is afflicted with technical difficulties. These consist in producing nozzles in an economical and, at the same time, simple manner through which the flat fluid jets flow with a thickness that is as uniform as possible from one end to the other. At present these nozzles are manufactured in such a way that they have essentially straight and parallel edges which open into a collecting container to which the pressure medium is fed through a series of lines distributed along the entire collecting container; In order to achieve flat jets with a constant flow, numerous baffles are provided in the interior of the container immediately behind the mentioned edges or lips in order to make the outflow direction of the fluid from the collecting container through the mentioned lips uniform.

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However, this solution requires a complicated and consequently expensive construction.

Furthermore, although the nozzle lips are straight and parallel, they must also be shaped so that the Width of the flat jet in the middle of the galvanized steel strip is slightly smaller than that for the two edges' the optimal width intended for the tape. It was found that this flat jet thickness differed leads to a larger order quantity, within certain limits, in the middle of the galvanized strip. However, the thickness of the flat jet must on the edges of the galvanized strip, innex alb certain limits, with different bandwidth in be kept essentially constant. This need has been met in accordance with the known state of the art It is sufficient that part of the nozzle is fixed and part is movable, or better still, is in each case interchangeable, as a result of which it becomes possible to obtain the desired layer thickness on the band edges depending on the respective band width. This solution, which is excellent in terms of its mode of operation, has not proven to be advantageous in terms of construction proven, since a different pair of lips is required for each band width.

♦ *

The subject matter of the invention makes it possible to eliminate this disadvantage and the thickness of the flat jet as a whole The length can be varied as required, resulting in a continuous instead of a discontinuous control of the layer thickness is possible.

Further advantages of the claimed device can be found in the following description.

The device according to the invention for the continuous control of the uniformity of the zinc application a sheet in the form of a zinc bath with controlled. Temperature exiting band, with two

711912l25.ii.7i

_ "Essentially horizontal collecting tanks, which immediately above the bathroom level on both soaps of the sheet metal strip are arranged and each have a slot-shaped, elongated nozzle forming two lips from which a flat jet of fluid can flow down onto the strip surface, is characterized in that at least one of the the nozzle outlet forming lips is elastically deformable, whereby a change in the opening width of these slit-shaped Nozzle even during operation and without any influence on the flat jet, both in its entire length as from one point to another, according to any chosen one Regularity achievable isfc. The cross-section of each collecting container must be in relation to the delivery pressure of the flat fluid jet and the flow through it must be sufficient so that the fluid is essentially stationary in the interior of the container remains or assumes a movement that is negligible in relation to the flow velocity of the flat jet is small.

Each collecting container is fed by at least one line which opens into the collecting container. The diameter of the collecting container is 100 to 300 mm when the inside diameter of the nozzles is 0.5 to 1.5 mm and if the delivery pressure of the fluid is between 600 and 1800 mm water column.

The collecting container has a wide, elongated opening pointing downwards and in the direction of the sheet metal strip, which gradually tapers into a nozzle shape by means of two lamellar lips, the upper lip being fixed and the inside sloping downwards about 30-60 °, while the inside the lower lip is substantially horizontal; furthermore, the inside of the upper lip is shaped so that its edge is substantially parallel to the inside of the lower lip.

711S12625.ii.7i

-T-

In the vicinity of the fastening point of the underside of the lower lip, an advantageously slot-shaped notch is provided on this, whereby elastic bending is possible under the action of pulling and / or pushing elements provided on the underside at certain intervals. The specific distance between the pulling and / or pushing elements allows the bend to be changed along the entire length as desired and consequently also the opening of the nozzle (and thus the thickness of the flat fluid jet) from point to point over the entire length change. The mentioned pulling and / or pushing elements of the lower nozzle lip are spaced bolts projecting below the lower lip; the lower end of each bolt is individually connected to remote-controlled axial adjusting elements by means of corresponding countershaft elements

Angularly arranged countershaft elements are provided for the two slot-shaped nozzles.

In order to move the two slot-shaped nozzles closer to or away from the steel strip, horizontal ones are also used Control elements provided.

The collecting containers are each suspended by means of supply lines provided in pairs, which lead into the two ends the collecting container open out; these supply lines are advantageously each one horizontal axis that is parallel to the corresponding slot-shaped nozzle can be pivoted stored.

The inner nozzle, that is, the nozzle from which the fluid jet emerges

one -

flows onto the / surface of the steel strip, against “whose other Ob6r f 1 äch.6 θi η6
/ The stabilizing roller immersed in the bath is pressed a little higher than the other slot nozzle. The inner nozzle, when it is in its lowest position, directs the fluid jet flowing out of it against a plane substantially perpendicular to the metal bath; the fluid jet from the other nozzle is inclined downwards by 10 °.

711t1I825.ii.7i

The subject matter, features and advantages of the invention are explained in more detail by the following description of an exemplary embodiment and with reference to the drawing. Fig.) A side view of the embodiment one vertical to the plane of the fluid jets vertical plane and

2 shows a cross section through a nozzle intended to form a flat fluid jet.

1 with a tensioned between two guide rollers, not shown, metal band is referred to, which in the direction of Arrow 2 is drawn from a molten zinc bath 3 maintained at a certain temperature. A stabilizing roller 4 is used to support the support plane of the metal strip 1, mainly opposite the air jets generating nozzles 5 and 6, to position exactly, which are in a small Distance above the mirror 7 of the bath 3 are; this distance should advantageously be 150 to 500 mm be; as explained below, these may be small which are difficult to achieve by the conventional devices Distances can be maintained more easily by means of the nozzles according to the invention. . - '

The nozzles 6 and 5 are each fed from a collection container 8 or 9 , which is arranged at the side and which are advantageously formed as two circular lines, the diameter of which is large in relation to the fluid jet. j This collection is carried out exclusively by one

Line IO or 11 fed, which can be pivoted about horizontal transverse axes by means of rotatable sealing joints 14 and _J5 12 and 13 are stored. These joints each have a toothed segment 16 and 17, which mesh so that one Rotation of the line 11 is always the same and opposite * corresponds to the set rotation of the line IO and vice versa.

The rotation of the lines IO and 11, which of course creates a relative approach and distance of nozzles 5 and 6 from each other and generated by the metal strip 1 is effected

by a pair of double-acting jacks 18 attached to the two Ends of the collecting container 8 and 9 respectively arranged or directly connected to the kußenr laughs of the lines OK and 11 and the-ia also have the task of supporting the collecting containers 8 and 9 on both sides. With 8 'is the Collecting container 8 referred to in a laterally tipped position. The lifters 18 are used for this purpose, the nozzles 5 and 6 - in the rest position to lift off the metal band and also to change the distance of the nozzles 5 and 6 from the metal band and accordingly also the To change the angle between the fluid jets and the belt 1.

As shown in FIG. 1, in the advantageous embodiment the two fluid jets are arranged slightly offset in height, namely the inner nozzle 5 is provided somewhat higher than the outer nozzle 6. "Inner nozzle" means that nozzle which directs its air jet against that surface of the metal strip which is remote from that which is in contact with the regulating roller 4. According to the embodiment shown , while the inner nozzle 5 is in its lowest position essentially perpendicular to the belt 1, the outer nozzle 6 is inclined downward by approximately 10 °. This difference in inclination naturally remains when both nozzles are swiveled outwards to adjust the distance from the sand 1. "

In Fig. 2, since the nozzle 5 has the same construction form, the nozzle 6 is shown enlarged. Hit 8 again denotes the one cylindrical collecting container, which has a flattened and essentially horizontal surface 20 on the outside and at the bottom, which serves as a contact surface for a console 21 for the control elements of the nozzle opening over the entire length of the nozzle. In a direction inclined downwards by approximately 45 °, the collecting container has a large longitudinal slot 22, on the edges of which an upper lip 23 and a lower lip 24 are fastened, for example by screwing them on. While the upper

Lip 23 is fixed, the lower lip 24 can be elastically inclined downwards, since a longitudinal groove 26 is provided near its attachment point on its underside. At certain intervals, bolts 27 which are arranged at a distance of, for example, 10 cm from one another, pass through the lip 24 , the heads of which are located in corresponding bores so that they do not protrude beyond the top of the lip 24. The lower end of the bolts 27 can be pulled down by certain amounts that are different for each bolt,

(ι whereby the thickness of the fluid flowing out of the nozzle 6 ; ·; "strahl Hber_ the entire length can be controlled at will.

There is consequently the possibility of influencing any bandwidth so that the thicknesses of the fluid jet in the center of the band and at the uprights assume the different desired values. Furthermore , it is also possible to change the thickness of the beam along the width of Bj.:->*?b 1 from a minimum value in the middle of the strip to a maximum value at the edges, the thickness being linear, parabolic, circular or otherwise takes. It is noteworthy that, according to the invention, the thickness of the fluid jet also varies from point to point, and

v- can be changed even while the device is working . Such a possibility does not exist in the already known devices. The elements that are intended to control the distance between the lips, that is to say the bolts 27, never interfere with the fluid jet

In the solution shown in FIG. 2, the lower end of each bolt 27 is rotatable and axially displaceable by means of bushes attached to the bracket 21. A part of the bolt shank is provided with an external thread in order to screw a rotatable but not axially displaceable bath 30 thereon.

- Ii -

This wheel 30 has a helical toothing on the circumference, which in a second, not shown, at a V7inkel of 9 0 ° arranged toothed wheel engages through a remotely controllable shaft »31, even while the device works, can be set in rotation. The bolt 27 can of course also by means of other mechanical means be moved axially.

It is essential that the diameter of the . · -. Collection container 8 large in relation to the thickness of the fluid jet is chosen. The diameter should advantageously be 100 to 300 mm. The diameter size should but in the correct relationship to the delivery pressure of the fluid, to the thickness of the fluid jet and in particular to its flow rate can be determined so that the pressurized fluid contained in the container 8 is practically at rest remain. This sets the orientation of the fluid jet Remain the same over the entire length and there will be no turbulence in the nozzle opening and no changes result in the flow of the fluid jet, that is, the dimensions of the collecting container 8 must be such that it can take over the function of a storage space. In this case the fluid is only allowed, at both ends of the container 8 and, in the borderline case, can only be supplied at one end so that there are no pressure fluctuations inside the container comes. In addition, the upper lip 23 must be inclined downwards by about 45 ° and the inside must be shaped so that it runs tangential to the inside of the lower lip 24 at the expiring end, the position of which the orientation of the Fluid jet determined.

For a preferred embodiment of the invention are the following operating parameters are provided:

711111125.1171

Pressure of the fluid Distance of the flat jets from the bath Distance of the flat jets from the belt Thickness of the flat jets Inclination towards the band Outer jet Inner jet

6OO - 1800 mm 150 - 500 mm 12 - 18th mm 0.5 - 1.5 mm approximately 80 ° approximately 90 °

Air is advantageously used as the fluid Room temperature.

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Claims (1)

ei aiii till III 1 ta · · · ι a · f - 13 claims 1) Continuous uniformity control device of the zinc application on a thin sheet in the form of one from a molten zinc bath with controlled Temperature exiting strip, with two essentially horizontal collecting tanks, which are immediately above the bathroom mirror are arranged on different sides of the metal strip, with both collecting containers one each Have slot-shaped, elongated nozzle formed by two lips, from which a flat jet of fluid onto the strip surface can flow down, characterized in that at least one of the lips forming the nozzle outlet is elastically deformable, whereby a change in the opening width of the slot-shaped nozzle, even during the Operation, without any influence on the flat jet, both over the entire length and from one to the other Point can be achieved according to any law chosen, and that the cross section of each collecting container in relation to the delivery pressure of the flat fluid jet and be sufficiently large for the flow that the fluid remains essentially dormant in the interior of the container or a Assumes movement that is negligibly small in relation to the flow velocity of the jet. 2) Device according to claim 1, characterized in that each collecting container is fed by at least one line which opens into the collecting container. 3) Device according to claim 1 or 2, characterized in that the diameter of the collecting container 100 to 300 mm is when the inside diameter of the nozzles is 0.5 to 1.5 mm, and that the delivery pressure of the fluid is 600 to 1800 mm Water column is. 711111125. «. 71 -U- 4) Device according to one of claims 1 - 3 _f, characterized in that the collecting container has a wide, downwardly and in the direction of the metal band open elongated opening which is elongated and / by means of two? * 'Lamellar lips tapers to a nozzle fona, wherein the upper lip is fixed and the inside inclined downwards about 30-60, while the inside of the lower lip is essentially horizontal, and the inside of the upper lip is adapted to the shape of the lower tip so that its edge is in the runs essentially parallel to the inside of the lower lip. 5) Device according to claim 4, characterized in that in the vicinity of the fastening point on the underside the lower lip an advantageously slot-shaped notch is provided, whereby under the action of on the underside at certain intervals provided pull and / or push elements an elastic bend it is possible that the certain distance of the. Train and / or Pushing elements from each other allowed to change the above-mentioned bend along the entire length at will and consequently also the opening of the nozzle (and thus the thickness of the flat fluid jet) from point to point and across the full length. €) Device according to claim 5, characterized in that that the pulling and / or pushing elements of the lower nozzle lip are arranged at intervals, below the lower one Lip protruding bolts are made and that the lower end of each bolt has a suitable locking element is connected to a single, remotely controlled axial actuator. 711t1lt2s.tt.7i • ■ · · • C · · I • t · · - 15 - 7) Device according to claim 6, characterized in that angular ta «Vo * lsgsslsincnt: s are provided for the two slot-shaped nozzles 8) Device according to one of claims 1-7, characterized in that horizontal adjusting elements are provided for approaching and removing the two slot-shaped nozzles to or from the metal strip. Supported 9) Device according to one of claims 1-8, characterized * in that the collection containers are held suspended by means of two supply lines, which opens into the two ends of the collecting supply lines advantageously about a horizontal axis parallel to the associated slot-shaped nozzle axis pivotally are. 10) Device according to one of claims 1-9, characterized in that the inner nozzle, that is to say the nozzle from which the fluid jet flows onto the / surface of the metal tape , is immersed in the bath against its other "surface ~. -_...-.... - - - / Stabilization roll is printed, a little higher _, is ranked as the other nozzle. ' O. Device according to Claim 10, characterized in that the inner nozzle, when it is in its lowest position, moves the fluid flowing out of it into a substantially perpendicular direction to the metal bath directed plane directs, wherein the fluid jet of the other nozzle is inclined by 10 ° downwards.