PT692549E - METHOD AND METHOD FOR CONTROLLING METAL COATING WEIGHT USING GAS KNIVES - Google Patents

Abstract

A gas wiping die is provided with a predetermined arrangement of cams (41) which act against a flexible lip (21) either directly or through intermediate push rods (31) or the like to adjust the opening of the wiping die orifice (29). The invention may involve several cam shafts (43) which may be rotated by a so-called stepping motor or motors. The arrangement allows a smooth progression of changes in the opening and camber of the coating die gas orifice slot. Various contours of cam shaft may be provided to provide easily implemented programs of die adjustment, either smoothly or discretely, to adjust for variations in coating conditions or procedure. <MATH>

Description

6325-43.

\] V

'METHOD FOR WEIGHT CONTROL OF METALLIC COATING, USING GAS KNIVES &quot;

BACKGROUND OF THE INVENTION (1) Field of the Invention The present invention relates to the coating of metal strips with uniform coating weights and more particularly to the determination or control of coating weight in hot, with the designated &quot; gas doctors &quot; or gas knives, and in particular to the use of gas knives with adjustable orifice. (2) Description of Background Various means have been used to control the coating weight of the so-called strips or sheet material with hot dip coating and particularly sheet material and strips based on ferrous materials which are passed through baths in lead-tin alloy melt, zinc, aluminum, aluminum-zinc and the like. During the coating of this type of material, as the ferrous substrate material exits the surface of the bath, it draws with it an amount of molten metal that is at least temporarily adherent and that, as the ferrous material passes, above, solidifies on the surface of the base material. If the strip or sheet material is withdrawn from the bath in an orificantly slow manner, the excess of molten metal will flow from the surface in a manner

by providing a coating thickness or weight depending basically on the temperature of the substrate, as well as the coating and physical characteristics of the non-solidified coating material, particularly the weight or specific mass. However, since the speeds of coating lines have been increasing, a large excess coating of the melt bath is drawn onto the surface of the substrate, which did not have sufficient time to flow back into the melt bath, resulting in in a coating of excessive thickness, as well as not uniform, of the coated product. A number of resources have been utilized to remove this excess coating from the surface of the substrate, including charcoal or the like, floating on the bath surface, stationary scrapers (wiper) between which the strip passes, so-called coating rolls, between which the strip passes and, in more modern practice, gas jets, which remove the molten coating, returning it to the bath, leaving the desired residual surface layer which then solidifies, forming the final coating of the substrate. The use of coating rollers or &quot; doctor rolls &quot; between which the ferrous substrate passed, as it exits the melt bath, constitutes a significant improvement in the coating of sheet material, or in strip, with hot metal, and for some time the use of these rolls has become very sophisticated design and implementation. These coating rolls essentially limited the amount of metal exiting the metal bath with the substrate, then allowing the metal to be coated again with hot metal from the small capacity metal reservoir located between the rollers. The coating weight could be controlled by the pressure applied between the rollers and

by the depth at which the rollers were submerged in the melt bath. Almost all sophisticated coating roller systems have now, however, been supplanted by gas cleaning scrapers or even more sophisticated fluids which are more flexible and have a longer life span and generally perform a better job at a lower cost.

In the gas or fluid scraping process as used in the steel industry, a gas, such as steam, air, nitrogen or other gaseous fluid, is forced out of a storage chamber through a slot or slot and is directed against a strip or steel sheet coated with molten metal as it passes upwardly, from the melt bath, passing to or near the side of the slit. The narrow, elongated gas jet coming from the slit removes excess molten coating from the surface of the metal base and generally smoothes the molten surface. These gas scraping devices are generally referred to as knives or fluid scrapers, or, in the case of air being the scraping fluid, usually by knives or wipers. They are also often called &quot; air doctors &quot;.

Fluid scraping techniques have evolved into very sophisticated systems and various designs have been developed for scraping or smoothing various cast coatings including zinc and aluminum and combinations of zinc and aluminum. A persisting problem has been the designation of accumulation of material at the edges, wherein the coating is thicker at the edges of the coated material, generally due to less effective scraping at the edges, as a result of interferences between gas jets opposite directions, which scrape the two opposing sides of the strip material, or sheet metal. This implied the use of 3

V

larger slit dimensions at the ends of the holes, or gas scraping slits, near the sides of the strip material, or sheet. However, since the final coating weight is a function of several factors, essentially including the strip speed or line speed, strip width and surface finish, strip temperature, as well as temperature of the melt bath, the distance between the gas injector and the strip, the gas flow through the nozzle and the nozzle configuration, is difficult and in fact, as far as is known, to provide an injector or slit with a width and configuration, which are suitable for all coating conditions. In addition to the above factors, there is still in any particular coating bath the additional complication of each coating material having its own characteristics, which inherently alter the characteristics of the scraping operation. For example, molten zinc is inherently heavier than molten aluminum, so the effects of gravity tend to be more pronounced, in most cases a weaker jet of scraping gas is effective to remove more zinc coating material, than aluminum coating material. The amount of material accumulated on the edges is also probably significantly smaller. Thus, when changing from one coating material to another, it is usually necessary to use a further coating nozzle or a wiper air nozzle, it being necessary not only to change the nozzles or the wiper shavings, with a negligible work, but also to maintain a stock of different injectors and nozzles, which is not at all economical.

Changes in the speed of the line during the operation of a coating bath, cooling the strip, 4 particularly if it has been heated in batch ovens instead of continuous ovens, changes in bath temperature and similar parameters, may also have a considerable influence on the scraping of the cast coated surface, with a fluid scraper. For example, the melt bath and the strip or sheet to be coated rarely have, if at all, similar temperatures when brought into contact, upon immersion of the strip in the bath. Accordingly, if the strip is colder, the bath will tend to be cooled and if the strip is warmer the bath tends to be heated as the strip passes the bath and the bath will tend to recover at intervals between the strips. This factor in itself causes the coating of the strip to progressively vary, with a given profile, from end to end. Although small, this variation may be important for some products and may be of relatively high economic significance in large-scale operations, where any excess coating may assume considerable importance in the cost of coating.

It was therefore recognized that it would be desirable to have an infinitely adjustable slit width within normal operating limits which could in particular be adjustable during operation of a coating line so as to make it possible to make adjustments of other Variable factors of the coating operation, as well as make deliberate changes when desirable. For example, it may sometimes be desirable to change the coating weight partly by coating a bobbin to meet the requirements of a particular order, or in like situations. 5 r- Ll

I

It would be particularly advantageous if the width and configuration of the slit of a gas scraping die could be varied or varied easily, not only between orders, or depending on the coating conditions, but also as a coating operation progresses. Among the above attempts to provide variable apertures, to make the desirable changes in the coating of a substrate, the following may be mentioned: U.S. Patent 2,415,644 issued February 11, 1947 to L.W. Leonhard et al., Describes an initial form of &quot; ducLor blade &quot; or air knife for smoothing and scraping the coating of a strip or mesh. Changes in coating weight obtained by altering various parameters of the coating process, including gas pressure, width of the gas scraping aperture, and other solutions are mentioned or discussed. Leonhard et al. describe an air knife with two halves held together by adjusting and securing bolts. These bolts, which pass through the center of the closed chamber, may, in one embodiment, be adjusted by a mechanical arrangement, so as to adjust the gas passage opening between the two halves of the die body, in accordance with a system of control. Although the apparatus of Leonhard et al. be designed especially for the coating of non-metallic meshes and the like, and intended to operate on only one side of the mesh, would probably also apply to the coating of strip and sheet metal materials. U.S. Patent 3,753,418 issued August 21, 1973 to R. Roncan, discloses a rasp spreading system for sheets and strips of ferrous material incorporating a non-adjustable upper lip, opposite a flexible or adjustable lip. The flexible lower lip can be adjusted by means of a mechanical screw system which, through a series of rotating arms and intermediate gears, forces the flexible lip up and down, so as to adjust the distance between the lips. It is mentioned that a differential adjustment can be obtained along the length of the lip. U.S. Patent 3,841,557 issued October 15, 1974 to E.S. Atkinson discloses a gas scraper spinnerette, wherein the width of the slit from which the gas is supplied may be selectively adjusted by means of heating elements placed at small intervals in one half of the spinnerette. Atkinson, in his discussion of the background, describes the prior use of removable chocks or inserts and the use of adjustable bolts or bolts to push the walls of the gas passageway relative to one another. These previous methods were, however, slow and overly laborious. U.S. Patent 3,917,888 issued November 4, 1975 to D.J. Deam et al. Discloses a gas scraping die, wherein the width of the aperture can be selectively altered by sliding a variable shim onto a lip. The rate of decrease in aperture thickness can be adjusted by inserting different adjusting strips into the lip. U.S. Patent 3,938,468 issued February 17, 1976 to JB Kirschner discloses a gas scraper spinner with a variable slit valve mounted on or between the lips of the gas passage of the spinneret in order to change the effective cross-sectional of the aperture. The valve is in the form of a substantially round or long, bar 7 piece.

mounted in a circular aperture between the ends of the die. The circular piece has a relief with a pattern along one side to form a variable valve surface so as to allow gas to escape beyond the rotary valve part. US Pat. No. 4,106,429 issued December 15, August 1978 to IJ Phillips discloses a gas scraper spinnerette, wherein the scraper aperture can vary in size by moving the ends of the wiper aperture of the spinneret longitudinally toward or away from the material to be scraped. The lips are moved longitudinally relative to the remainder of the wiper die. This longitudinal movement is effected by means of a rotating cam device, supported within the lip structure itself. By rotating the meat, it causes the movable lip structure to slide laterally relative to the remaining structure of the wiper die, effectively extending or shortening the lips. U.S. Patent 4,524,716 issued June 25, 1985 to H.J. Mueller, discloses a recent gas scraper spinneret, particularly for use in the paper coating. The Mueller die has convergent lips and has a flexible gas flow modifying part, in the shape of a half sphere, directly behind the lip opening. This ball may be moved toward or away from the opening in the lips so as to open or close relative to the aperture, thereby controlling the gas flow from the lips. U.S. Patent 5,127,581 to Kuwano et al. describes a fluid pipe for use with mechanized sprayers for powdered chemicals, blowers

cleaning and the like. The projection tube has an aperture at the end and has oscillating, variable, or forwardly extending throttling means from the normal outlet of the projection tube. These oscillating output pieces are engaged in one another by means of an intermediate link mechanism which coordinates the opening or movement out of one outlet piece relative to the other. The coupling mechanisms act together as a coupling unit, to rotate the coupling between the two output pieces in opposite directions. While this US patent is intended for a special type of nozzle, with operating principles different from the means of the present invention, it generally describes two variable position output pieces, which are spring loaded, so as to move them (by means of an independent spring) and having a mechanical arrangement to overcome the action of the spring, depicting interlocking devices for coordinating the movement of the two variable position output pieces. The toothed device described in this U.S. patent shows gears, a jaw or a closure part of a pair of catch parts together, so that they have an equal movement. The actual movement of the jaws is not, however, effected by the engagement between the two. If this US patent were combined with, eg, US: 2,415,644, this would result in coordination of the opening of the two sets of output pieces, so that they both operated identically or were opened or closed identically, as they were geared together. If the general arrangement set forth in U.S. Patent 5,127,581 has been changed to a presumably less preferred cam device, just mentioned once, this camming device would then also be used as a connecting unit to simultaneously rotate both variable output pieces, in directions opposites. 9

Japanese Patent Abstracts vol. 17, no. 373 (C-1083), 14.07.93. JP-A-0559 514 discloses a method of folding the lip extending from a lip body upwardly or downwardly passing through a holder secured to said lip with the lip thereof, while the other The end of the support is mechanically coupled to a rotary shaft provided with a cam. In this way, it is possible to change the width of the nozzle slit between the upper and lower lips by adjusting the support. However, it is not possible to variably control the contour of said slit. EP-A-0 566 497 uses a rather complicated structure of individual pistons, arranged along the upper lip body and acting thereon. Said plungers are independently so as to vary the profile or contour of the slit aperture between the lips. 0 Japanese Patent Abstract vol. 16, no. The use of an L-shaped lever, which is supported in an oscillating manner, acts on the lower body which is lip-stiffened and which is depressed. to the lower part of one of several actuating means located at its other end. Again, this construction is quite complicated. Further, the fit of the slit is restricted to the adjustment capability of said lever system.

Patents FR-A-2 136 041 and FR-A-2 290 313 use conventional screws and oscillating shafts and self-adjusting bolts in the upper and / or lower lip bodies in order to vary the gap or nozzle defined therebetween. The disadvantages of these arrangements have already been borne out. 10

As can be seen from the above descriptions in the previously patented gas scraper troughs there has been a large number of attempts to produce a practical wiper die having a variable and preferably infinitely variable die opening. However, each attempt had some drawbacks, and no really satisfactory arrangement for varying the contour of the lips of the gas nozzle has been conceived or developed in order to vary the gas flow through various beads of the gas nozzle to permit different conditions in a coating line. There is thus a need for a gas scraper spinner or &quot; doctor gas &quot; particularly for scraping and smoothing the molten metal on the surface of a strip or sheet iron material which can be varied conveniently in cross-section so as to rapidly vary the amount of gas from the die at any point along the length of the strip. face of the spinneret, in order to allow variations in the operation of the coating line.

It is therefore a main object of the present invention to provide a gas scraper die or a simpler and more reliable construction, which can be easily driven and whose width of the scraping aperture can vary, section by section, or from point to point, to along the face of the die, so that changes in the operating parameters of a coating line can be adjusted.

It is yet another object of the invention to provide a gas scraper spinneret wherein the aperture of the gas scraper aperture can be easily varied in a suitable manner along the face of the spinnerette and can be readily varied in a pre- defined along the face of the die, thus making changes in the coating operation. 11

It is further an object of the invention to provide an infinitely adjustable aperture along the face of a gas scraping die so as to facilitate control of the scraping gas force on various portions of the coated strip or sheet passing through the spinneret die. coating.

It is yet another object of the invention to provide an arrangement for differentially varying the width of the aperture in a gas scraping die by means of a device with a predetermined position cam shaft which acts directly on the lips of a scraper die .

It is still another object of the invention to provide an arrangement for varying the aperture of a gas scraping die opening along the face of the die by means of a predetermined shape of a rotary cam follower, controlling the position of the lips.

It is still another object of the invention to provide an arrangement for varying the aperture of a wiper die by means of an easily replaceable cam follower.

It is yet another object of the invention to provide a method for varying the scraping of a strip or sheet material with a gas scraping die during the coating of a single length of coil in a predetermined manner to enable the removal progressive in-line, or coating conditions during the coating of a single coil.

It is yet another object of the invention to provide an apparatus with a coating die 12

It is effective to vary in a precise and convenient manner, in a predetermined manner, the size of the scraping aperture of a gas scraping die by means of a single, effective mechanical arrangement.

It is yet another object of the invention to provide a convenient and effective arrangement for varying the aperture along the face of the gas scraper die by means of a series of interconnected meats.

It is yet another object of the invention to provide a convenient and effective arrangement for varying the aperture of a gas scraping die by means of a series of interconnected meats or a cam follower extending more or less parallel to the die opening and acting on a flexible lip of said spinnerette.

It is yet another object of the invention to provide an arrangement for varying the aperture of a gas scraper die using more than one camshaft.

Further objects and advantages of the invention will become apparent from the following description and discussion taken in conjunction with the accompanying drawings. The preferred solution of the invention is defined in claim 1. Preferred features and embodiments are defined in the dependent claims 2 to 14. The apparatus advocated by the invention is suitable for smoothing and scraping liquid material on a strip, strips lined with molten metal liquid, or liquid coating material in a flat base material. The method of the invention according to claims 5 to 7 may be advantageously carried out with a meat device as defined in the previous claims relating to the device.

SUMMARY OF THE INVENTION The present invention provides a wiping die for scraping (cleaning) cast coatings onto a flat material passing through a molten coating bath, in particular a molten metal coating bath. A wiper die is provided with at least one flexible or movable lip which is permanently forced in one direction and pulled in the opposite direction, tending to open or close the opening of the wiper blade by means of a multi-skin device. The various cams are mounted on or integral with a camshaft which is in mechanical contact either directly or indirectly with the flexible lip. Rotation of the camshaft causes the various cams or the various sections of a cam or cams to exert more or less force against the movable or flexible lips so as to adjust them so as to open or close the aperture of the die at the effective point associated with the diameter of each particular cam in order to control the passage of the scraping gas through this part of the aperture of the wiper die. More than one cam shaft can be used to exert a variable force against the flexible lip. Preferably, a motor or stepper electric motors is used to operate the shaft or cam shafts, which control the aperture between the lips of the die opening, at various positions along the aperture. The cam shafts may be used in conjunction with and / or be replaced by different assemblies 14

of meat shafts with different contours, to vary the possible adjustments. Meat shaft assemblies in arrangements of equivalent functionality may be used to progressively vary the opening of the wiper blades in a predetermined manner as a strip passes through a coating line in order to make the necessary adjustment in the changes that naturally occur in the distribution of the coating from one end to the other of the coated strip. The applicant has proved that by providing a device with differential meats on a meat shaft, the meat being in contact with a flexible lip of the wiper die, it is possible to obtain a very practical and economical method and means for differentially adjusting the lips of the wiper die , along the face of the strip and temporarily along the strip, as the coating proceeds. The arrangement of the invention is, on the whole, simple, practical and economical.

In the apparatus of the invention the cam follower is preferably provided with a number of slightly pronounced meat designs, providing different contours of the lip openings in a predetermined time-related sequence when moved at a speed controlled by a motor means connected thereto .

In addition, the meat shaft can advantageously be provided with various, varying, gently varying meat surface designs so as to provide a predetermined sequence of the opening of the lips to the over time, matching each one as the designs of the cameo move at a certain speed by effect of the means attached to them. The sequence in time is essentially dependent, not on an external sequence of phenomena, but directly on the predetermined contour of a camming device which can be designed to correspond to external phenomena, such as the velocity of the liquid level, the length of the strip, temperature or any of the various other parameters but is nevertheless preset once it is ready.

Figure 1 is a cross-section of a preferred embodiment of the improved wiper spinning die of the invention. Figure 2 is a longitudinal view of the wiper die shown in Figure 1, viewed towards or towards the wiper aperture, but in which the upper lip of the die has been removed. Figure 3 is a schematic sketch of a camming device and driving device from the front of the wiper die. Figure 4 is a top view of a typical cam follower of the invention showing various cam diameters and contours of this shaft. Figure 5 is a schematic sketch similar to Figure 3, but an alternate embodiment of the invention incorporating two cam shafts. Figure 6 is a schematic sketch of another alternate embodiment showing three cam shafts 16

provide additional flexibility with regard to the action of cameo. Figure 7 is a cross-sectional view of an alternate embodiment of the invention wherein the meat device directly contacts the flexible bottom lip section of the wiper die from the exterior of the wiper chamber. Figure 8 is a longitudinal view of the device of Figure 7 seen in the direction of the passage opening of the scraping gas, wherein the protective cover, normally mounted on the meat device, has been removed. Figure 9 is a cross-sectional view of an alternate embodiment of the invention, wherein the cam follower directly contacts the flexible bottom lips from the inside of the wiper chamber of the wiper. Figure 10 is a front view of the embodiment shown in Figure 9. Figure 11 is a cross-section of an alternate embodiment of the invention, wherein the camshaft contacts directly with the upper lip of the die, from inside a chamber. Figure 12 is a front elevation of the embodiment shown in Figure 11. Figure 13 is a schematic outline of a control system associated with a pair of rasp spindles similar to those shown in Figures 1 and 2 and mounted on a facing line by hot dip. 17) Figure 14 is a side elevation taken in a longitudinal direction of a meat shaft produced in accordance with a conventional arrangement or embodiment of the invention. Figure 15 is a side elevation taken in a longitudinal direction of an integral meat shaft and meat arrangement according to another embodiment of the invention. Figure 16 is a side elevation taken in a longitudinal direction of another embodiment of the present invention. Figure 17 is a top view of a contour of the meat arrangement on a cam follower in accordance with the present invention. Figure 18 is a top view of an alternate contour of the cam shaft in an alternative form of embodiment of the present invention. Figure 19 is a graphical representation of the contour of the coating of a coated strip having a differential outline from one end to the other, wherein said strip has been coated without using the present invention. Figure 20 is a graphical representation of the contour of the coating from one end to the other of a coated strip produced using the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

As noted in the previous introductory notes, the final coating weight in a metal coated strip 18

hot is a function of a number of factors, including (a) the speed of the line, (b) the width and finishing surface of the strip, (c) the temperature of the strip, (d) the temperature of the melt bath, (e) a (f) the gas flow through the nozzle and (g) the nozzle configuration, which determines the configuration of the gas stream coming from the gas knife against the strip. One of the main factors is the configuration of the gas stream coming from the gas scraping aperture of the gas scraper die. In addition, the conditions tend to be altered as the coating process proceeds. Accordingly, it would be desirable to have a universally adjustable gas scraper aperture in the gas scraper die, which could be adjusted not only with respect to the relative size of said aperture, but also with respect to the contour, or relative aperture along the extension side of the gas passage. In other words, it may be desirable in some operations for the gas scraper aperture to be relatively wide in the center to narrow toward the two ends so that a stronger jet of gas exits from the center of said aperture. On the other hand, it is most often desirable for the ends of the gas passage openings to be relatively wider, so as to achieve a stronger gas discharge from the tips or ends of the aperture, providing a greater scraping action at the tips of the strip, where a strong coating tends to form, mainly due to interference between two oppositely directed gas currents or curtains coming from two oppositely directed gas scraping apertures located on opposite sides of the strip, together the edges of it. This is the so-called scraping phenomenon of the edges or the sharp edges. If a sheet or strip with an edge of uniform weight is wound from 19

the edges of the strip are progressively turned upwards as the hob is rolled, causing unstable winding conditions and in the case of a strip having a great length, the result is that strong bends occur when the strip is unrolled. Coils of this kind often require a separate flattening performed before use. Further, overcoating at the edges is an economic disadvantage since if the specification for the thickness of the coating is reached at the center of the coated strip, the sides of the strip will be overcoated, resulting in a substantial loss of material which cost can not be recovered due to the fact that the coating weight meets the less stringent generic specification.

Various arrangements and mechanisms have been proposed in the past to adjust the width throughout the aperture of the coating die or, alternatively, to adjust the shape of the aperture. These methods may basically comprise the provision of a plurality of wiper blades with various configurations of the apertures. These arrangements may also comprise separate lip arrangements with differential or adjustable apertures between them. Another alternative, which has been used with some frequency but not widely, has focused on arrangements where the lips of the wiper die can be adjusted either mechanically, usually by rotation of a threaded spindle to move the lips of the wiper die towards or away from one another or, in at least one case, thermally, to differentially vary the shape and aperture between the lips of the wiper blade. While these various methods for adjusting the lips of a gas scraper die have had some success, they do not

have been generally satisfactory. A major drawback of these prior systems has been the multiple adjustments that need to be made in order to differentially adjust the lips of the coating die. This may require the use of multiple control and motorized means. Accordingly, practical, easily operable and adjustable means are required to universally and differentially adjust the aperture between the lips of the wiper die or between several portions of the lips of a wiper die. The present invention provides the practical arrangement, therefore, for varying the aperture between the lips of a wiper die based on a predetermined drawing, as well as to produce changes in the calibration of the wiper die in response to varying conditions, in a coating line .

These varying conditions may involve changing an order to another order, often resulting in different metal calibrations, different heating conditions, or different coating materials. For example, an order may require a calibration of strip or sheet material and the order immediately following may require a different calibration.

Since the metal to be coated rarely, if at all, enters the coating vessel, any new calibrated strip entering the coating vessel will, or draw heat from the coating vessel to a greater or lesser extent, or add heat to the coating vessel. coating vessel to a greater or lesser extent than the immediately preceding strip of a prior order. In many cases, the material to be coated will be heated to a higher temperature 21

during pre-treatment, than the melt coating bath, depending, of course, on the coating bath composition, thereby taking advantage of this additional heat, to maintain the temperature of the coating bath. However, a larger gauze strip or sheet of the same temperature will add more heat to the melt bath by shifting the bath temperature upward over a period of time resulting in different scraping properties of the molten metal once that the heated metal string enters the bath at a very high speed, it can cause relatively significant temperature changes in a very short time. However, while adjustments of the heating of the coating vessel can be made through its main heating means to counterbalance changes in the heating of the strip, these changes can only be made relatively slowly. If relatively rapid scraping gas adjustments can be made, however, these other changes can often be compensated for.

Although the gas pressure and hence the volume of scraping gas have previously been relatively quickly adjustable, the differential adjustments of the scraping gas through apertures have not been conveniently achieved with respect to speed. The differences that differential heating can make on the relative coating weight along the width of a strip may, using the present invention, be compensated by altering the relative aperture of the slit of the coating die. This is done by adjusting the cam arrangement of the invention to force one end of the coating die more or less relative to the opposite lip to open or close that particular portion of the die aperture 22

V coating, as may be suitable for maintaining uniform coating conditions on the strip.

The characteristics of various coating materials such as, for example, zinc, aluminum and combinations of zinc and aluminum are also different and the calibration of the coating along the face of the strip varies in a manner particularly dependent on the weight or density of the coating, since different densities cause more or less coating material to flow downward along the surface of the strip, returning to the melt bath, merely by the force of gravity. Normally, by altering the coating material in the vessel, it will be necessary to also change the wiper spigots so as to have a wiper spigot with an aperture contour suitable for that particular coating material. Obviously, however, changing the coating strips entails additional cost factors and, even when carried out while changing other elements of the coating bath arrangement, still requires additional personnel, not to mention the danger to the peo3oal when working above or in the vicinity of a hot metal coating material. Using the present invention, however, i.e. using a meat arrangement to vary the width of the slit aperture in the coating die, rapid changes from one coating material to another can easily be made by simply using a cam with sectors along its diameter suitable for various alternative coating materials. This further allows a certain possibility of specialized variation in the cam which will allow the process to be adjusted to the particular specialized changes that may be encountered for any particular coating material. Alternatively, a different meat shaft with 23

a different meat relationship can be easily replaced by a previously selected meat shaft to change the available adjustment of the aperture within the available aperture limits during the operation. The following description in conjunction with the accompanying Figures is intended to explain the advantages as well as the operation of the process of the invention and the construction of the equipment necessary to implement the process of the invention.

In Figure 1 there is shown a gas scraped coating die 11, which comprises a chamber having more or less angled side walls 13, which includes an open filler chamber 15. It is to be understood that the filler chamber 15 extends into and out of the plane of the drawing, forming a relatively large open space for receiving a scraping gas, such as air, steam, nitrogen or other suitable gas, to be used to provide an elongate gas jet from the aperture of the wiper die , to scrape the surface of a strip of metal passing through the opening of the wiper die. This scraping gas can be supplied to the filling chamber 15 through manifolds 14, from which a suitable gas is fed through conduits 16 to the filling chamber 15. The wiper die 11 is also provided with an upper lip 17 secure on the side walls 13 by connecting pieces 19, usually large industrial or machine screws. Likewise, the lower end 21 is also secured to the side walls 13 by machine screws 23. It will be understood that the machine screws 19 and 23 are positioned more or less in line along the face of the coating die, as if shows in several of the figures, for example Figures 3, 5, 6 and 8 showing the connecting pieces of the upper lip 19. The lower end 24

of the upper lip 17 is indicated by reference 25, while the outer end of the lower lip 21 is indicated by reference 27. These ends 25 and 27 are contiguous with each other and define between their surfaces a narrow gas passageway 29, through which the jet of scraping gas passes, or gas sheet. This aperture of slit 29 may have an operating width of three (3) centimeters to 4.5 centimeters (0.762 mm to 1.143 mift) and is preferably adjustable in accordance with the invention within the range of 0.025 to 0.050 inches (0.635 mm to 1.27 mm). As can be seen in Figure 2, this arrangement is quite critical and can be performed along the extension of the lip through the action of a continuous series of pressure bars or adjustment 31, as shown in Figure 3, only one shown in Figure 1. These bars 31 are arranged so as to press down the lower lip 21 to move it away from the upper lip 17. It should be understood that there is a series of adjustment bars 31, as shown in Figures 2 and spaced apart from certain intervals along the wiper die, fixed in such a way as to be able to exert downward force, against the lower lip at various positions along the length of the wiper die. The lower lip 21 is in turn arranged so as to have a natural elastic action which will tend to bring it back or flex it towards the upper lip 17. Thus, the elasticity of the metal on the lower lip is chosen so as to tend to close the aperture of the slit 29 (propensity to close), while the adjusting bars 31 are selected so as to resist the closure and maintain the aperture of the slit sufficiently open to permit the exit of the amount of gas from which is intended to be passed through that particular portion of the slot. 25 V, γ ~~.

The tops of the adjusting bars 31 pass through a series of bushings 33 mounted on the upper surface of the sidewalls 13 of the coating die 11. As can be seen from Figure 11, the bushes are disposed on a step 35 at the top of the walls side portions 13 of the wiper die 11. However, it should be understood that the bushes 33 could be located at any convenient location in the upper portions of the coating die 11. The upper support end 37 of each of the adjustment rods 31 is made to contact a plurality of cam surfaces 39 of the cams 41 spaced along a camshaft 43. The camshaft 43 extends longitudinally along the step 35 of the wiper die and is supported conventionally in bearings suitable, not shown, at the ends or positioned at strategic intervals along the step 35 or, in other words, along the raspage die As shown schematically in Figure 2, the cam shaft 43 may be rotated either by manual adjustment from a suitable crank or other non-shown manual means to apply a torque to the camshaft 43 , or may be preferably by a remote actuation means such as an electric stepper motor or the like driven remotely away from the coating line or at least away from the immediate vicinity of the hot metal bath. Motorized control of the position of the camshaft can be controlled by manually or computer operated controls, as shown for example in Figure 13. Figure 3 shows the camshaft end driven by a chain system 47 from the stepper motor 49, through the action of worm gears 51 and 53 respectively mounted on the camshaft end and in the direction of the stepping motor. The stepper motor 49 is shown pervaded on a console. This console 55 comprises the end of a structural piece or support 57 which passes through the top of the wiper die 11 and is attached to the upper part of the side walls 13 of the wiper die in any suitable way. It is to be understood that the carrier 57 may be replaced by any arrangement suitable to support the wiper die and / or the stepper motor 49. m

Figure 4 shows an enlarged top view of the cam shaft 43 with a series of cams 41 spaced apart from varying distances and different configurations arranged in various positions along the extension of the cam shaft 43. Typically, the cams 41 located in or oriented to the ends of the cam shaft 43 will be larger in overall diameter or &quot; higher &quot; in their larger portions, than the cams 41 facing the center of the camshaft 43. The smaller diameter portion of the cams 41 may be substantially the same height as the surface of the camshaft 43, or be mere extensions of the cam surface 41. came from cams. Alternatively, they may comprise slightly pronounced cam sections on a separate shaft, as shown in Figures 1 to 3.

As can be seen in Figures 1 and 2, when the camshaft 43 is rotated by the stepper motor 49 shown in Figure 3, the cams 41 will be rotated to various positions, depending on how much the stepper motor 49 is rotated. If the camshaft 43 is rotated from an initial position in which all surfaces of the cams are at the same height or distance from the center 59 of the camshaft 43, as shown in the upper left-hand side of the cam 4, to a position round of 180 degrees from position 27

the meats will be brought to a position where the Lancia day of the meat surfaces 39 of each meat will be a maximum distance from the center 59 of the camshaft 43. This will press the pressure bars or adjustment bars 31 as are shown in Figures 1, 2, 3 and 4 downwardly until they reach a point dependent on the diameter of the cam which is supported by its bearing surface 37. Since the cams 41 marked by A, B, C and D 3, at the ends of the coating die have the largest maximum diameter, in descending order, the pressure rods 31 at the ends of the die will force the bottom lip 21 of the die downwardly, further at the ends of the coating die than at the points closest to the center of the coating die. The minimum stress occurs at the center of the coating die where the surface of the multi cam cam 39 shown in Figure 3, for example L, M and N, in increasing order from the central cam, L, has the minimum diameter or the minimum distance between the center 59 of the camshaft and the outer surface 39.

It may be seen from the foregoing that when the camshaft is at the minimum position, ie when the surface of the cam 39 is at a minimum distance from the center 59 of the camshaft 43, the silhouette of the aperture of the slot 29, or, for example, In other words, the gap between the aperture in the ends of the aperture of the coating die and the aperture in the center of the aperture of the coating die will be the minimum. In the event that the cam surfaces are all at the same height at this point, the coating die will be arranged so as to have an aperture having the same magnitude along the entire extent of the aperture. When this cam shaft, however, is rotated 180 degrees, the distance between the center of the camshaft 59 and the surfaces of the individual cams will be maximized and the aperture will have a maximum value, at all times.

I · and zones. Since the end meats are normally arranged so as to have a maximum distance at this point between the axis of the camshaft and the surface of the cam, the outer portions of the wiper die will be open to a maximum value when the camshaft is in this 180 ° position. Rotation of the camshaft at an intermediate angle between the minimum and the maximum will provide several intermediate apertures in the slit of the wiper die. Thus, by machining a cam shaft with various configurations and then moving or rotating this cam shaft to a series of predetermined positions, in order to take advantage of these configurations, a regular sequence of die adjustments can be obtained. These settings can be made for various operating conditions. For example if it is desired to operate the line with a relatively large differential between the value of the opening of the coating die in the center and the value of the aperture of the coating die on the sides of the die or at the ends of the die in order to maximize the suppression of accumulations on the edges, the cam can be turned to the maximum differential position. However, if for some reason the coating buildup is significantly less in another operation, the cam may be turned to a less extreme position.

Alternatively, if the coating conditions tend to change while the line operation continues, the stepper motor can be progressively operated to turn or rotate the camshaft and provide different values of the apertures of the coating die, so that to allow adjustment to varying conditions. Although use has been shown of a camshaft arrangement for illustrative purposes, wherein the contour of the die opening slot is relatively or differentially more open at the ends of the die as the total die slot 29 is enlarged in width of the aperture particularly to compensate for the build up of accumulations on the edges, it should be understood that the cam shaft arrangement of the invention may be made with a relative contour, which will compensate for various other changes in coating conditions and changes depending on the operation.

In Figure 3, the arrangement shown in Figures 1 and 2 is seen from the outside of the die in front of the die opening. A number of cam diameters, rising along the face of the wiper die, can be seen from the center and it should be noted that the value of the aperture of the slit 29 in the die base is larger at the ends. The lower ends of the pressure rods or adjustment bars 31 can be seen through the aperture of the slit or aperture of the slit 29, as can be seen in Figure 3. The pressure bars or adjustment bars 31, although visible in Figure 3, have a very limited diameter in an actual installation, so that they do not seriously interfere with the flow of gas in the slit of the wiper die. In order to minimize any interference in this flow, it is desirable that the adjusting bars 31 be positioned rearwardly, as far as possible from the aperture in the slit, as shown in Figure 1. Other designs may place the pressure bars even further away from the aperture of the slit. Figure 5 is similar to Figure 3, but shows an alternative embodiment of the invention, in which there are two separate cam shafts, each having separate stepper motors 49a and 49b. It is often found that the coating operation has become uneven and that one edge of the coated strip or sheet has a heavier coating than the other edge. In this case, it may be desirable to adjust differently the apertures of the die 30 f

of coating on opposite edges of the strip. The arrangement shown in Figure 5 allows this independent adjustment of the die openings adjacent the two edges. Thus if, for any reason, the formation of a thicker edge occurs in an adjacent area of one edge of the strip, the coating spinner may be more open at a point adjacent the edge, so as to allow adjustment of the coating of that strip side, by applying a stronger jet of coating scraping gas on that side. It will be understood that in the apparatus of Figure 5, a series of meats in each meat shaft will have different maximum diameters, usually based largely on having a smaller / maximum in that part of the meat to be used midway through the die and a larger diameter / maximum on the part of the cam shaft which will be mounted close to the edges of the coating die. Instead of having a generally curved configuration, which would first provide a maximum aperture, decreasing to a minimum aperture near the center of the die and again to a maximum aperture close to the other end of the die, each individual meat shaft has only a plurality of diameters which will provide a minimum value of the die apertures at one end of the camshaft and a maximum aperture at the other end, when the camshaft is rotated to its position with a maximum differential. As indicated above, this particular sequence is only illustrative of a contour frequently used for opening the die and different interchangeable contours can be provided. As in the arrangement shown in Figures 1, 2, 3, and 4 the camshafts in Figure 5 may be adjusted either manually, by crank, or preferably by means of stepper motors, as shown. When an automatic control system is used to control the operation of the stepper motors, it will, of course, be necessary to incorporate a somewhat more sophisticated control means to maintain 31

the relative rotation of the camshafts in the desired ratio. When there are two contiguous meat shafts, it is usually desirable to have the minimum height of the uniform flesh completely around the two adjacent adjacent meat, so that when these two ends are placed close to one another, the adjustment of the adjacent parts of the die lips is the same regardless of the relative position which the adjustment of the two cams may take. For convenience of illustration, the aperture of the slit 29 is shown in Figure 5, evenly along its width. Figure 6 shows an alternative arrangement of the invention which provides not only two separate meat shafts but three separate meat shafts, 43a, 43b and 43c, each operated by a separate stepper motor 49a , 49b and 49c. As will be understood, this arrangement provides some flexibility advantages of the coating line, but also has a greater complexity and may be useful only in certain specific liners in which overall flexibility is particularly important. The meats and slit openings are once again shown as uniform for convenience and in fact variations on the actual installation may be so small that they will hardly be detected with the naked eye.

Although the arrangement shown in Figures 1,2,3, and 4 and the variations thereof shown in Figures 5 and 6 are very effectively and easily implemented, the adjustment bars which extend through the filling chamber of the coating die introduce, minimal turbulence and possible variations in the scraping gas jet, at the exit of the slit from the gas scraper die. 32 |

Figure 7 shows an alternative arrangement for a rapping die, wherein the cam shaft 43 and the cams 41 are supported on bearings, not shown, mounted on structural support brackets 63 connected to or constituting extensions of the sidewalls 13 of the coating die; see Fig. 8. The camshaft 43 and the structural supports 63 are mounted below the wiper die in a position such that the surfaces of the meats are supported against the underside of the lower wiper 21 of the wiper die . The rigid structural supports 63 urge the surfaces of the cams 39 strongly against the lower part of the flexible bottom lip 21 of the wiper die, so that the relative elevations of the surfaces of the cams change relative to one another while the camshaft rotates , the flexible lip may be pressed more or less inwardly so as to partially close the opening of the slit 29. In the embodiment shown in Figure 7, it is to be understood that the flexible bottom lip 21 is arranged to have the normal flexing directed towards the outside so that this flexing is counteracted by the surfaces 39 of the cams 41. The upper lip is disposed essentially in the same position as the die shown in Figures 1 to 4. It is preferred that there is a cover 65 mounted on the cam shaft 43 and cams 41, so as to prevent them from being spattered with hot metal from the melt coating bath located under the melt scraping scrapers. Obviously, if there is molten metal splashing on the surfaces of the meats, this would at least temporarily change the shape of the critical machining of those surfaces and interfere with the correct operation and tensioning of the lower lip 21 of the wiper die 11. Figure 8 is a the side elevation of the wiper spindle shown in Figure 7, seen in the direction of the slit 29 and 33, having the cam shaft 43 and the various cams 41 arranged in the same main structure of the wiper spindle. In Figure 8, cover 65 for the cam shaft arrangement has been removed so as to better show the arrangement of the cams. It will be understood that, since the camshaft is positioned below the lower lip, there is absolutely no obstacle in the filling chamber 15 which may interfere with undisturbed passage of the scraping gas from the manifolds 14 of the chamber 15 and which exits through the aperture of the tear 29. The arrangement of a feed motor by foot 49 at the end of the wiper die is shown in Figure 8, in a position enabling the camshaft 43 to operate. Figure 8 shows a chamber for operation of the die aperture 29, which increases in outward sides. Figure 9 shows yet another embodiment of the invention in which the cam shaft 43 and the cams 41 are positioned directly on the flexible bottom lip somewhat somewhat like that shown in Figure 7 except that the cams are positioned above the lip 21 rather than below the lip 21. It will be understood that the permanent tension of the lip 21 will be, in the case of Figure 9, directed towards the upper lip 17, rather than tending to move away from it, as in Figure 7 Preferably, a smooth contour cover 67 is provided within the filler chamber 15 of the wiper die shown in Figure 9. This smooth contour cover prevents swirling formation unavoidable when using cams and camshafts voluminous materials interfere with the gentle flow of gas from the filling chamber 15 and passes through the slot 29. One cam the camshaft 43 and the cams 41 are kept completely inside the structure of the die are in a very clean, uncontaminated atmosphere and are therefore not

it is necessary to maintain a sealing contact between the cover and the flexible lower lip, 21. This allows the lip 21 to be easily flexed without interference from the cover. This cover 67 is, as indicated above, present not so much as a protective cover to protect the meats 41 and the cam shaft 43, but also to obtain a smooth gas flow along the cover, which could otherwise be , to undergo swirling deformations, as it passes over the unequal surfaces of the cams. It should be noted that both the height of the cam shaft as well as the height of the cover 67 were shown exaggerated in Figure 9 for better viewing. Figure 10 shows a longitudinal exterior view of the wiper die shown in Figure 9. It should be noted in Figure 10 that the slit does not appear to be constrained by the presence of adjustment rods or other exterior mechanical devices which may inert into the smooth flow of the wiper. gas from the opening. Figure 11 shows another alternative embodiment of the invention, wherein the flexible lip is the upper lip 17 and this lip is pressed through the interior by means of a rotating meat system. As in Figures 7 and 9, the cam shaft 43 and the cams 41 supported on this shaft are, in turn, supported on a structural support 69, which is securely attached to the end of the upper side wall 13. In Figure 11, the flexible lip 17 is permanently pressed down towards the filling chamber and the cams 41 will serve to press this lip 17 outwardly away from the filling chamber and also from the slot 29 so that the slit is held open to allow the scraping gas to pass therethrough as a thin curtain serving to scrape the

surface of the strip or sheet from the coating bath which passes beyond the end of the wiper die 11. Both the structural support 69 and the cam shaft 43 as well as the cams 41 attached thereto are preferably protected by the cover 71 , which, as can be seen in Figure 11, is securely attached to the inside of the sidewall 13 of the coating die, extending downwardly over the meat assembly, to protect them generally, However, there is provided a space or gap 73 between the end of the cover 71 and the inner surface of the flexible upper lip 17 to permit movements of the flexible lip 17. As in the forms of the flexible lip 17 is pressed so as to flex normally in a direction opposite to that in which it is forced out by the surfaces of the meats. Although some scraping gas goes into the chamber where the meats are located behind the cover 71, this will not result in injury, since the gas, even in the case of a vapor, is clean and unpolluted. As in the previous embodiments of Figures 7 and 9, it can be seen in Figure 11 that the cam arrangement is substantially misaligned with respect to the slit, so that neither the cams nor the cover on the cams interfere in any way with the gas exiting the slit 29. Figure 12 is a front view of the coating die of Figure 11, which shows the opening of the die and is clean in appearance, as in Figure 10.

It will be understood from Figures 7, 9 and 11 that although the cams are shown in the form of a single cam normally rotated by a stepper motor mounted to one end of the spinnerette, double or multiple cams may be used, as shown in Figures 5 and 6. 36

Figure 13 shows a schematic of a coating apparatus used in preferred rasp spindles of the invention, such as those shown in Figures 1 to 4. In Figure 13, a reservoir of coating material 81 for a metal of the type suitable for the hot dip coating in a molten coating metal bath 83 contained in the reservoir 81 is equipped with a dip roller 85 held at a predetermined depth within the molten metal 83 and a stabilizer roller 8b just below the surface of the molten metal. A metal strip, such as a steel strip 87, passes into the hot metal through the surface after having passed through guide rollers 89, 91 and 93. The guide rollers 89 and 91 are in the interior of the furnace of muffle 95, wherein the strip is heated, usually in a reducing atmosphere, before passing to the molten metal 83. A pair of gas scraping spindles 97 and 99, which, as indicated above, are substantially identical to those shown schematically in Figures 1 to 4 are supported on structural support parts 101 and 103 in which they are hinged at 102 and 104 at a predetermined height above the hot metal bath. The steel strip 87 rises from the diver 85 in addition to the stabilizer roll 86 and between the gas scraper spinnerets 97 and 99 in a position such that each side of the strip will be scraped by a preheated pressurized gas curtain , coming from the slot of each wiper die. The wiper blades 97 and 99 both have cams 107 and 109 which act through pressure rods 111 and 113 to urge the lower lips of wiper blades 97 and 99 to provide a gas curtain of differential thickness, which scrapes the surface of the strip 87 so as to establish the desired thickness of coating on that surface. The wiper spindles 97 and 99 are partially shown with portions torn away to show vertically extending pressure rods 111 and 113 on the inside. The gas curtain coming from the slits of the gas scraping die serves to scrape the excess coating back into the coating bath 83. The gas for the wiper die 97 and 99 is provided through heads 115 and 117, to which the gas is supplied from any suitable source. An electric stepper is provided for each coating die 97 and 99 designed to control the rotation of the cams 107 and 109. At the same time, main computer control means 121 is used to control the scraping of the strip or sheet, in an automatic way. The computer control means 121 is itself controlled from a console 123 which can provide, by direct manipulation, input data indicating which coating thickness to apply to the surface of the strip or sheet, the computer has a plurality of sensors 125, 127 and 129 for respectively sensing the temperature of the strip from the muffle furnace 95 passing through the throat or throttle 96, the temperature of the hot metal bath 83, the thickness of the coating on the strip from the the detector being on one side of the strip marked as detector 129A and the detector on the other side of the strip marked detector 129B. A further detector assembly, again with a detector on each side of the strip, is comprised of a pair of coating thickness detectors 131A and 131B provided above the coating cores. The two detectors 131A and 131B detect the final coating thickness after the strip has passed through the coating detectors and, preferably, after the coating has solidified on the surface of the strip, although this is not strictly

required. Each of these detectors is connected to the control of the main computer by means of a suitable signal line.

A control line also passes from the control of the computer 121 to each of the heads 115 and 1.17 feeding gas to the coating nozzles as well as to the stepper motors 119 which control each of the meats. These control lines serve to automatically position the meats to open or close the slit or scraper apertures of each wiper die by placing them in the best differential aperture along the spinneret for each of the particular coating conditions. They also control the amount of gas passing through the heads through means, usually of the butterfly valve type provided in the heads. These additional control features are not shown as they are conventional in the art.

Figures 14, 15 and 16 show for comparison purposes elevations of cam shaft shapes 43 which are integral with or separate cams 41, rigidly attached to their surface, similarly to those shown in the foregoing drawings. In Figure 14, the cam shaft is shown by itself with a series of shafts with differential proportions, equally spaced along the shaft. The overall silhouette is shown in a generally convex and non-concave shape, as shown in the other illustrations, to illustrate that various contours of the cam shaft may be utilized for the various control functions. It can be seen from figure 14 that the top of the meats in the camshaft has a series of substantially parallel cam surfaces, while the camshaft lower part, i.e., at 180 ° of the parallel series of meat surfaces, has a generally convex arrangement of cooperating meat surfaces which define, as is shown, a convex shape which, it should be understood, can also be concave and can be more usually of concave profile . The meat arrangement shown in Figure 14 is especially designed for use with the spigots shown in Figs. in which only a pressure bar or adjustment rests directly on the flexible lip which is in turn directly displaced by the meat or alternatively these surfaces of the meat rest directly on the surface of the flexible lip of the coating die. It will be appreciated that various configurations and combinations of meats can be used in combination to obtain various final conformations of the flexible surfaces. Figure 15 shows a modified type of meat wherein the meat shaft itself provides essentially the surface of the various meats of the various sections. This arrangement constitutes a substantially solid meat arrangement which, it should be noted, essentially has the same general profile of the surfaces of the meats of Figure 14.

A disadvantage of the arrangement shown in Figure 15 is that the surfaces of the meats are inclined at the same angle as the overall change between the positions of the cam. This is a disadvantage due to the point of contact with other mechanical means being inclined which may tend to be detrimentally displaced laterally, particularly when it comes to the operation of the adjustment bars, shown in Figures 1 to 4. However, this disadvantage can be obviated providing a camshaft as shown in Figure 16. In the camshaft shown in Figure 16, each of the cam locations for operating a pressure bar has a uniform surface parallel to the camshaft center axis, so that there, 40 η; i

- in fact, cam surfaces 61 &quot; smooth &quot;, although curved upwards, for seating the pressure bars. It will be understood that Figures 14 and 16 are substantially equivalent, except that excess metal has been removed between the cam sections of Figure 14, so as to produce a lighter, but not necessarily stronger, structure or more economical.

Various cam silhouettes can also be used. For example, in Figure 4 there is shown a normal cam contour, with a progressively greater distance between the center of the camshaft and the edge of the cam surface, from one part to another. Another possible arrangement is shown in Figure 17, in which instead of the maximum distance between the center of the camshaft and the surface of the cam, ie the highest uniform section, is located 180Â ° from the part having the least uniform section, the distance from the surface of the cam from the center of the camshaft increases, on the contrary, continuously from a minimum distance as the cam rotates until the maximum distance between the two points is at a point about 300 or more degrees around the camshaft rotating in a given direction. The distance between the surface of the cam relative to the center of the cam follower then abruptly decreases so as to bring it back into the uniform minimum or lower section. The arrangement shown in Figure 17 provides a wider range of possible adjustments along a camshaft, of the same diameter as the camshaft arrangement shown in Figure 4. In other words, in Figure 4, the increase in size of the cam cam shaft occurs along half the periphery of the cam shaft while in Figure 17 the same increase in size occurs over more than three quarters of the periphery of the cam or camshaft, basically allowing for a larger increase which will result in a thinner control with less precise movement of the camshaft. The lowermost portion of the cam in Figure 17 is at 61A, while the maximum cam diameter is at 61B, rather close to the first.

Other arrangements are also possible such as, for example, those shown in Figure 18, wherein the surface of the cam progresses through a series of smaller, greater distances between the center of the camshaft and the surface of the cams. As can be seen in Figure 18, the series of steps 133 provides larger areas, for example 133A and 133B of height of the more or less uniform cam action and also of the pressure bar. This arrangement also has advantages in achieving greater accuracy of movement with a less precise primary actuator. In other words, a stepper motor or other means for providing movement does not have to be as accurate in operation to achieve a given elevation at the surface of the cam. Instead, some predetermined desired surface elevations are soon machined on the surface, that the stepper motor or similar device has to be achieved only with little precision and are maintained during a significant dimension of the cam, as the camshaft rotates, so that fewer risks are encountered than those occurring when an inaccurate opening of the lips occurs during an abnormality in the operation of the motor means. Those skilled in the art will be able to design other possible variations of cam surfaces to operate the cam of the invention. Figure 19 is a graph showing schematically the calibration of the coating or the thickness of a long strip or sheet passing through a coating bath, wherein the strip or sheet is cooler than the bath. Line A refers to the thickness of the coating at one edge of the sheet and line C refers to the thickness of the coating at the other edge of the sheet, while line B represents the thickness of the coating at the center of the sheet. Calibration of the coating thickness is graphically shown in the abscissa of the graph in relative terms, i.e. an increase in coating thickness is represented by the increase in line position for each coating, that position being plotted according to the &quot; index marks &quot; on the left and right sides of the graph. The &quot; Index marks &quot; however, do not translate any absolute values beyond the marks being spaced a thousandth of an inch (0.0254 mm) apart. Accordingly, if the coating of the strip increases by one thousandth of an inch (0.0254 mm), or &quot; mil &quot;, the line elevation will go from an &quot; index mark &quot; for the next. These three graphs A, B, and C for different parts of the strip do not therefore indicate that the coating is thicker at A than at C but only show the relative increase in coating from one end of the strip to the left from the graph to the other end of the strip to the right of the graph.

It can be seen in Figure 19 that the center of the strip tends to be coated in a thicker form but only to a relatively small extent, whereas the edges of strip A and C have increased coating thickness due to a "heavy edge" coating effect, which becomes relatively more pronounced as the bath temperature decreases, due to the cooling of the strip entering the bath, causing more material to adhere to the surface of the strip, basically because the material of molten coating becomes slightly more viscous with decreasing temperature. 43

Fig. 20 shows the same type of graph as Fig. 19. In the case of Fiy, 20, lines X and 7 represent the relative thickness of the coating on the edges of a strip or on the surface of a nearby strip of the edges, while the X line indicates the thickness of the coating at the center of the strip. The coating line in operation, shown in Figure 20, is an illustration of the typical results expected from a line such as that shown in Figure 13, when equipped with a medium as a camea device which, in the figures shows gradually increasing the opening the gas passage and the gas scraper spouts particularly close to the edges of the spouts as the coating process proceeds from one end to the other of the strip to be coated. It should be noted that the predetermined curvature of the profile covered by the surfaces of the meats effectively compensated for the progressively increasing viscosity of the coating by increasing the apertures of the gas scraping die in a manner sufficient to counterbalance this viscosity increase by scraping the coating at more of the surface of the strip. The control system 121, shown in Figure 13, by detecting the temperature of the strip and the bath material, operates the stepper motors by rotating the surfaces of the meats in a manner that will maintain both the temperature of the bath material more constant while at the same time compensating for the increase in viscosity of the melt bath material, increasing the jet of gas from the slit die slot. Since essentially the same series of increases tends to occur in each coating bath subjected to this phenomenon, a cam can be designed relatively easily to correct such changes. 44

As will be appreciated, if the relative increase in the flesh surfaces of the cam shaft shown in any of Figures 14, 15 or 16 is anticipated and carefully calculated and the speed of the stepper motor changeover is also carefully conjugated by a computer or even alternatively by manual means, the continuous compensation shown by Figure 20 for a slow and undesirable increase in the amount of coating on a strip can be readily compensated. It should be understood that if the rotation of the meat is done manually, the compensation will be somehow in steps, since very fine adjustments will not be possible. However, three or four adjustments of the rotation of the meats during the passage of a strip will be somehow effective in smoothing the coating. Of course, however, the motors should be controlled by computer. Alternatively the motors may be manually operated, but again with the stepwise adjustment that such a process allows. It will still, on average, result in a uniformly coated strip.

It is also to be understood that a coating line utilizing the meatshaft adjustments of the present invention will normally have a series of meat shafts which can be readily replaced by each other, depending on the operation of the line. For example, a given line may have a main camshaft which will be responsible for most of the changes in one line and which will allow the line operators to make compensations particularly during a period in which heavy edges or other situations occur. However, at the same time, other specific meat shafts can be produced and these can be stored in place for offsets when specific conditions advise or, to provide for a specific adjustment of the apertures in the coating knives. 45

While the present invention has been described in some detail and with some particularity with respect to some embodiments, the invention is not intended to be limited to any particular embodiments or embodiments but should rather be considered broadly with reference to the foregoing claims, in order to provide the widest possible interpretation of those claims, in view of the scope of the prior art and thereby to fall within the scope contemplated by the invention.

Lisbon, 22 February 2001.

THE OFFICIAL AGENT OF INDUSTRIAL PROPERTY

Claims (17)

Adjustable wiper blade for smoothing and scraping (wiping) liquid coating material applied onto flat elongated material passing through the spinneret, using a fluid scraping means from said spinneret, comprising: (a) a die body (11) comprising a filling chamber (15) and an elongated opening (29) along the outlet side of said fluid scraping means, (b) means for supplying the pressurized fluid scraping means to said filling chamber, (c) a pair of fluid confinement pieces (17, 21) on either side of the elongate aperture (29) to define the aperture between said fluid confinement pieces and, therewith, the conformation and / or dimensions of any medium stream (d) and rotatable cam means (41, 39) for altering the width of the aperture (29) characterized in that (e) one of said fluid containment members is elastic and is permanently (f) said constrained, elastic, confining member being in direct physical contact or indirect physical contact through pieces of said fluid confining part, (31) which can follow the contour of the surfaces of the cams (39) when said cam means are rotated, with at least two differently contoured cam position surfaces (39) arranged and constructed so as to forces the fluid restraining pieces, at two different points, in line with the aperture 1 elongate, in the opposite direction of said propensity, which will redefine the conformation and / or dimension of the elongate aperture and, therefore, the flow of any scraping fluid passing through the elongate aperture. (g) said pressure pieces (31) for said indirect physical contact extend from the inner side of said permanently prone confinement piece (21), through said filling chamber (15) towards said filling surfaces (39), being disposed outside said filling chamber (15) and above said other fluid confining part (17) in the case of said indirect physical contact, and (h) said surface of the variable position meat be adjustable, in regard to its positioning, by means of producing movement. The adjustable wiper blade according to claim 1, wherein the pair of fluid confinement members comprises resilient integral lips (17, 21) of the wiper die, the lower lip being preferably prone in said diameter. The adjustable wiper blade according to claim 2, wherein a plurality of variable position cam surfaces with different contours (39) are in at least indirect contact with the elastic lips (17,21). The adjustable wiper blade according to claim 3, wherein the plurality of variable position cam surfaces (39) are disposed on a cam shaft (43) rotatable by the motion producing means. 2 V ι t The adjustable wiper blade according to claim 4, wherein the variable position cam surfaces (39) are in indirect contact with said permanently prone elastic lips (21) by means of several intermediate pressure pieces ( 31), independent. The adjustable wiper blade according to claim 5, wherein the plurality of independent intermediate pressure pieces comprise independently movable pressure rods (31) extending between the variable position cam surfaces and said permanently elastic lips prone The adjustable wiper blade according to claim 4, wherein the surfaces of the variable position cams (39) are in direct contact with the permanently prone elastic lips (21) in order to press said lips in said direction. The adjustable wiper blade according to claim 7, wherein the variable position bed surfaces (39) are defined by substantially adjacent cams (41) mounted on a cam shaft (43) or wherein the cam surfaces position are defined by a continuously variable conformation surface formed on a rotating part. The adjustable wiper blade according to claim 3, wherein the variable position cam surfaces (39) are defined by a variable camming surface arranged along a camming part which is rotated by a motor (49), wherein the operation of the stepper motor to rotate the meat part is controlled by a control siotoma according to claim 1, predetermined pattern, based on the coating operation data supplied to the control system. The adjustable wiper blade according to claims 8 and 9, wherein at least two separate cams (43) are provided for adjusting separate portions of the elastic lips. The adjustable wiper blade according to any preceding claim, wherein said filling chamber (15) is connected to dispensing means (14, 16) to provide a scraping gas to said filling chamber. Apparatus according to claim 11, wherein the natural bending of the lip proceeds towards the opposite lip and the shaft and associated cam surfaces are supported within the adjacent filling chamber and in effective contact with one side of the flexible lip or alternatively where the natural bending of the lip occurs in the direction away from the opposite lip and the shaft and associated cam surfaces are outside the filling chamber in at least indirect contact with said lip. Apparatus according to claim 12, which further incorporates protective means separating the meats in contact with said lip from the main part of the filling chamber. 4 Apparatus according to claims 12 and 13, wherein the transverse shaft is rotated by means of a stepper motor. A method for scraping a sheet material or coated strip by means of a gas scraping die, comprising: (a) passing the coated material through the wiper die, (b) permanently and elastically pressing a lip of the pair of lips towards or away from the other lip of said pair, (o) adjusting the scraping gas flow through the gas aperture in the die, differentially along the extent of the aperture, in a predetermined pattern , the distance between the lips varying at different points along said permanently prone lip by means of a rotating camming device in direct or indirect physical contact with said lip, so as to force said lip in a direction opposite said direction and having a predetermined contour pattern of differential adjustment modes operable in discrete time periods during the operation of the coating line in order to provide vents with predetermined contours between the lips. A method according to claim 15, wherein a series of predetermined contour apertures is provided between the lips by means of a cam shaft with a plurality of differential cam surfaces associated therewith and with various discrete cam patterns, which provide different contours to the openings between the lips, in a sequence related to time. 5 A method according to claim 15 or 16, wherein the cam follower has a plurality of cam designs that vary in shape, defining concordances from one to the other, so as to provide a sequence of apertures which, in time, follow each other. Lisbon, February 22, 2001. THE OFFICIAL AGENT OF INDUSTRIAL PROPERTY. 6