DE2050836A1 - Method and device for the continuous galvanizing of steel strips - Google Patents

Description

• - ■ »- 7,

¹ ^ ¹ ■ iain 7ϋ October 1970

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Allied Tube & Conduit Corporation

Method and device for the continuous galvanizing of steel strips

The present invention relates to a method and an apparatus for electroplating strip material. It relates specifically to a method and apparatus for continuously electroplating this material, which is rolled flat or shaped or partially shaped by means of roll forming.

The electroplating of flat strips has heretofore been carried out in baths or tanks of molten zinc of considerable depth. The tape was fed into the bath by sliding it into the upper surface from above and after Passleren one or more guide rollers has been led out of the bath from the top surface. With this basic device and this process gave satisfactory results in terms of appearance, rust and corrosion resistance, The galvanized steel band is mostly self. no paver Product, but is a material that has to be molded into a desired shape. To do this was it has hitherto been customary to electroplate strip material of a fairly large width and to slit the material. Usually

ORIGINAL INSPECTED

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the slotted material is wound up and then used for shaping by means of Rolling! Orraung, cutting or punching transported somewhere If the material is slotted after electroplating, cut or punched, the side or other Edges are exposed, and they can be in these exposed places roast. A product with good resistance to rusting Reaching the edges over longer periods of time is due to the thickness of the material, which can be galvanized, set a limit. For example, in a test report by Frank J. CoIe of Republic Steel Corporation, Clevelanvl, Ohio, which during a meeting of "The Galvanuers Committee "was distributed in Oct" 19 ^> 3, found that the Degree of protection from steel strength achieved by zinc electroplating and the zinc thickness depends. In his report it is stated that that it was a general opinion of the industry that galvanic cathodic protection was used to protect the edges of galvanized Steel only protects to a thickness of 0.036 inches (about 0.092 cm) and less, and that his calculations believe this confirm ο

The known method is required to a considerable extent, since it has not been found practical to form strip material either partially or entirely in an electroplating path. One reason is that the length of the plating

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procedure according to the state of the art erf order 1 i ^ lieu web is made so that * - i: i additional Vfalzverfoimfii d ' ^j r web uneconomical or otherwise impracticable ji,

Therefore i: s is generally recognized in the industry, wi «οϊιρπ stated that 0.036 inches (about 0.092 ^ m): u cases represents the limit for di> - üatnidicke, which in a consecutive i'xuit'n They fell into disrepair, whenever they can be vanished, in which the slotted edges are exposed after electroplating. If it is possible, as in the case of the present invention, to carry out the slitting process before the galvanizing, then tapes that are strong * -! are as 0.036 inches ((-.Ua 0.092 cm), galvanized and "be obtained in an effective coating allei surfaces. This x ^3" result is achieved by the present invention may be galvanized with which band material in a continuous process, wherein the material may be formed or partially formed by rolling, stamping, or the like to produce a finished or partially finished product with the exposed edges electroplated. In general, one would roll forming electroplated ribbons up to 36 inches in width According to the present invention, tapes of at least this dimension can be used in continuous sheets.

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It is therefore the object of the present invention to provide a new one Method of electroplating steel strips of any desired Width to create so that the edges in sufficient Dimensions are protected even if the tape dirk is greater than 0.036 inches (approximately 0.092 cm).

Other problems in the known methods and devices caused that their operating costs increased because their flexibility on the type of tape that are galvanized limited kd> if not time-consuming and expensive To sr, hai t ver 1 a '· -. Reindeer used became. Other cost increase factors are the periodic shutdown time for servicing these elements, guides, sink rollers and other immersed moving parts · It is also necessary to periodically remove slag from the surface of the bath, for example. Complicated facilities are also required to maintain a desired bath temperature and dispersion of alloy material. In addition, if one wants to produce a galvanized steel product whose finished surface quality is important, for example in a consumer product, the use of subsequent coating devices, such as polishing rollers, is required, so that the cost and complexity of the system increase even further.

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Accordingly, the present invention seeks to provide a new method provide for continuous galvanization of steel strips, which is relatively lighter and less expensive to construct and maintain *

Further according to the present invention is a new method for the continuous electroplating of steel strips provided that much more easily than the earlier tapes can be wound when moving from one bandwidth to another should be transferred.

According to a further embodiment of the present invention a new process is achieved for the continuous galvanizing of steel strips, with which smooth: * flitter-free End products can be produced.

According to the present invention, there is also a new method of continuously electroplating steel strips can be achieved with the tape material, which has been formed into the desired shape by means of rolling, or which has been partially roll formed prior to electroplating, and which, after electroplating, is finished by rolling.

Further in accordance with the present invention is a novel method and a device for continuous electroplating

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on the surfaces of steel strips, which do not create waste of zinc that is used for electroplating _#

The above and other objects according to the invention are achieved by a new method of electroplating strips, with which the strip material in a substantially horizontal Level is moved through a zinc bath.

According to a further embodiment of the present invention, the tape can be flat or partially shaped Art to be processed.

Further features, advantages and possible applications of the present invention emerge from the following description combined with. the accompanying drawings.

Show it:

1 shows a schematic view of a device according to of the present invention, which is suitable for carrying out the method of the invention,

FIG. 2 is a schematic view of a zinc bath construction which is used to carry out the method according to FIG present invention is useful,

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3 shows a view along the line 3-3 according to FIG. 2,

Fig. K a schematic! isf he view of the forming rollers, which form part of the device according to the present invention and are suitable for carrying out the method thereof,

Fig. 5 is a side view of the tape material after it has been ^

was passed through the forming rollers according to FIG. 3,

6 is a schematic view of the forming rolls which can be part of a device according to the present invention, and which for implementation of the new method of the same are suitable,

Fig. 7 is a schematic view of part of the device, which for the use of an alternative Aus ^ guide form according to the present invention is suitable,

Figure 8 is a perspective view of one type of steel strip which is electroplated in accordance with the present invention can,

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Fig. 9A is a perspective view of a partially formed Form which can be electroplated according to the present invention, and

FIG. 9B is a perspective view of the mold obtained from FIG partially formed shape shown in Fig. 9A can be formed after electroplating.

Fig. 1 illustrates an electroplating device which is supplied with steel strip 2 from a strip roll k. The apparatus is arranged in a series of stages to operate in a continuous manner so that an electroplating coating is provided on all surfaces of the strip material 2. The advancement of the tape 2 is first effected by engaging it between the tape and forming rollers, which rotate at a relatively constant speed, thereby drawing the tape into the apparatus for processing. Since the lengths of the steel strips from the roll of tape k after a relatively short operating time of the device in its continuous activity reach the end, it is necessary to provide a means for the end 6 k of the tape from a roll to splice a further roller to the front end to join the tape in continuous lengths without the continuous action

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the. Device to interrupt »For this purpose a loop 10 is inserted into the belt 2, which is dimensioned so that it has a length which is sufficient to lead the belt continuously to the rolling mill, while the rear end 6 of the belt is held stationary is to splice it onto the front edge 8 of a new roll which has been moved into the position of use, for example by welding.

The. Loop 10 can be placed on a roller which runs on a car, is that which, in turn, shown traveling over a track in said US Pat. No. 3 _f 122, ll4 (Krengel) Similarly. A clamp 12 can be provided at the same end in order to hold the end 6 while the end 8 is welded onto it, for example by a welding device.

It is generally necessary to peel or condition the edges of the tape from the roll k because it is relatively rough and uneven. To these edges-Abgratuiig or

Conditioning can be accomplished by the facility 15 may be provided. This can consist of a rotating There are side burrs, which all small parts in front of » removed from each edge, or as milling tools on each Side, which protrusions from the edges take away ι

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Likewise, a strip cutting machine can be provided before the deformation, which cuts the strip unwinding from the roll k into several strips, not necessarily 1 of the same width, which can then be processed, including shaping, partial shaping and electroplating parallel to the production of a product, in which all exposed surfaces are galvanized.

In another embodiment of the present invention the tape is used to galvanize the surface of the tape 2 with zinc according to the present invention, first passed through several forming rollers l6, their shape and number sufficient to deform the flat strip into an arcuate shape shown in FIG. A first A pair of forming rollers come into engagement with the upper and lower surfaces of the belt, and this pair consists of a bottom roller 20, which has a slightly convex shape, and an upper roller 22, which has a slightly concave shape, to initiate the deformation of the belt to the desired shape · These rollers are provided so that their axes of rotation extend transversely to the direction of movement of the belt and are rotatable in the direction indicated by the arrows on their Ends is shown. As stated above, these rollers additionally engage the lower and upper surfaces, to give the tape the shape you want, and they

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effect simultaneously the drive and the forward movement of the belt through the device.

A second set of transversely extending rollers consisting of a lower convex roller 2k and an upper concave roller 26 may be provided. These rolls would have radii of curvature greater than those of rolls 20 and 22 in order to further give the belt the desired M

to give an arcuate shape "There can be further shaping rollers which consist of a pair of vertically arranged rollers 28 and 30 which are arranged opposite one another and which are driven around sleeves which are perpendicular to the axis of rotation of rollers 20, 22, 2k and 26" These rollers are provided with concave surfaces which engage the lateral edges of the belt 2 and press the latter further into the desired arcuate shape. A similar set of vertical rollers 32 and Jk are provided to similarly engage the side edges of the belt. These rollers are fastened in the device with their axes of rotation closer to one another than the axis of rotation of the rollers 28 and 30, in order to bring the belt 2 further into the desired arcuate shape. Using different combinations of forming rollers, of which the arrangement according to FIG. K is only one example of a combination which can be used, the belt can gradually from its flat shape as it is

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is illustrated in the right part of Fig. 3, in the arcuate shape can be formed as shown in the left part This figure is shown · In addition to the rollers actually forming or partially forming the belt, the Forming process l6 also include material guides 35, which consist of guide niles, which with the edge, the upper and lower part of the belt, adjacent to the edges on both sides of the same, and which inwards and outwards as shown by the arrows. Are such material guides provided, the roller can accommodate strip material of different widths by adjusting it inwards or outwards, without the need to change the forming rolls.

From Fig. 5 it can be seen that the belt 2 is in an arcuate shape Shape was shaped that has a radius of curvature R has. When the tape is formed as shown, the amount of zinc adhering to the surface becomes that required to obtain a coating that is firmly bonded to the surface of the belt, Has the desired thickness, good coverage of the entire surface and a good appearance · These results will be achieved without using additional zinc, because over-

Excess zinc is in a path over the sloping down Sides of the arched web back into the bathroom

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brought for reuse. At the same time, the concave lower surface of the belt is similarly using Excess zinc coated which returned to the bath The limits of the radius of curvature R relate to the thickness of the tape, where it is important to have one Not to exceed the minimum value for a given thickness in order not to deform the strip beyond a point, in which a return to its flat shape is no longer possible. On the other hand, a maximum value of the Radius R is determined by the need to bend a surface downward enough to drain excess zinc can.

After the bath is formed into the arcuate shape, it is advanced to the elements linearly aligned with it, to wash and pickle the surfaces of the belt in preparation for continuous electroplating. The washing and stripping of the device can be similar to that disclosed in U.S. Patent No. 3,122, ilA is, and it consists of a first stage 36, which is a provides heavy washing of this surface and a second stage 381 to provide a medium wash «How as disclosed in the Krengel patent, these washing operations can be in the form of solutions of alkali in hot

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Water can be made. After the alkali washes the tape is fed into a rinse stage 4O, where it is washed with rinse water is sprayed to remove the alkali from the surface. After the rinsing process, the belt can be used in the 42 can be stripped using a hydrochloric acid solution will. After a water rinse in a stage 44 and a steam rinse in a stage 46, the belt closes the entrance of an inert gas housing 48 advanced.

In the interior of the housing 48 there is a device to heat the tape to a temperature in the range of between 650 to 95O ° F (343 to 520 ° C) so that the plating process can be done faster. How contemplative the preheater is an induction heater including an induction heating coil 50, the surrounds the tape and has an electrical, not illustrated Power source is connected. There is also a bath of molten zinc in the inert gas housing, of which a part is located in a trough arranged in the housing. The construction can be the same as them in the aforementioned Krengel patent, it being noted that one in the mold is applied to the surface of the Band-matched and engaging device is provided at the exit end of the trough Wipe away excess zinc as the tape exits housing 48.

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To avoid flow and bulge formation, it is desired to freeze the metal as soon as possible after wiping it. To this end, a Vaster deterrent can be used in the form of a water spray process or a liquid coating 5 **, which essentially occurs after the tape exits the case.

From the Galvanisierabschnitt the plating is performed in the following hours by a series of Wassersprühabschnitten ^, the galvanized band uip cool, if it has not cooled sufficiently in another way during the freezing stage.

When it is desired to produce a flat belt, the apparatus includes a series of reforming rollers 56 Recovery rollers can be arranged as shown in FIG Fig. 6 is shown. First shown in this figure is a pair of transversely extending rollers 58 and 60, wherein roller 58 under belt 2 and roller 6O above it are arranged. When the surfaces of the belt come into engagement with the rollers, the arcuate Tape is pushed back into its flat shape. What number of rollers is always required can be provided and in this figure there is an additional set of reels

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62 and 6k which are arranged to rotate in the same direction as rollers 58 and 6O, but whose axes of rotation are closer to one another than the axes of rotation of rollers 58 and 6O.

After it has been restored to its flat shape, the band 2 can be cut to the desired lengths by means of scissors can be cut, or it can be on a supply roll twisted verderi, depending on the needs and desires of the user!

Instead of using the form and return form WalZfη, the straight described, the tape can be passed through the electroplating bath in a flat shape, but its longitudinal axis is inclined slightly from the horizontal .. This allows a sloping surface for the drainage of Excess can be provided without bending the tape. Instead of der.Formwalzen l6 roller guides can be used for this purpose provided his

An important feature of the present invention is the method for continuously electroplating the strip material in a continuous process. To this end, it is desirable to have the cleaned surface of the belt

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2 rait molten zinc for a time in contact to keep that sufficient to produce the desired reactions can take place, uir the desired electroplating thickness to form on its surface and it is important that Carry out reactions under non-oxidizing conditions, otherwise unwanted oxides of the metal were formed at the elevated temperatures under which the reactions are carried out, form «.

The desired reducing and non-oxidizing atmosphere can be achieved by enclosing the electroplating zone in a sealed Housing can be maintained in which a inert or reducing gas can be introduced while maintaining a non-oxidizing atmosphere o This can be accomplished through a sealed enclosure, but it is preferable to use an enclosure which can be removed to gain access to the interior of the electroplating zone "without the ability to regulate the atmosphere to impair in the position of use

The desired features have been achieved in the construction shown in Fig. 2 of the drawings by using a right-angled Hood 68 is used which has a horizontally disposed top wall 70, side and end walls 72,

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which extend vertically downward from the edges of the top wall into a trough 7k which is directed upward from a frame 76 which extends over the entire electroplating zone. The bottom edges 78 of the side walls are received in the trough for supporting the hood Trough is at least partially filled with a material 80, such as ζ.Β., fine sand, in which the lower edge of the side walls is embedded to create a seal all around that prevents the flow of free gases around for atmosphere control. One or more inlets 82 for the inert or reducing gas are provided in the walls of the hood in order to introduce this inert or reducing gas in quantities to maintain a non-oxidizing atmosphere therein.

With particular reference to Figures 2 and 3, it will be noted that the electroplating apparatus includes an elongated, horizontally disposed housing 52 in the form of a trough which is axially aligned with the path of travel of the belt 2, around the belt horizontally through an intermediate portion of the trough from an inlet 8k at one end to an outlet 86 at the opposite end. The trough is provided with one or more inlets 88 which are connected by a passage 90 to a container 92 of molten zinc, with means for

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Displacement of the molten zinc from the container to the inlets is provided at a rate that sufficient to keep the trough substantially filled with molten zinc around the belt moving therethrough to cover the inlet 88 may be adjacent the inlet 84 through which the tape is inserted, so that it flows through the trough at the same time as the molten zinc flows, in a position facing itself located above the tape so that the stream or streams of the molten zinc should be directed towards the belt.

The trough 52 is also provided with an outlet opening ° 4 in the Bottom wall 96 of the same, with a down pipe 98 from the trigger to the container. The vent has a small dimension to allow a thin stream molten zinc flows through it continuously, but in one Speed considerably slower than the rate of introduction of the molten zinc into the Trough, minus the amount that drains through the opening, so that an overflow of molten zinc over the sides of the trough which forms the inlet to the trough, but such an amount of molten zinc in the trough ensures that the tape leading through this is covered · It is preferable to use the ends of the trough

-A-

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higher than the sides, so that the overflow to the Sides takes place · In this way, the entry of the tape under the surface of the bath is ensured in the trough without having to use its prepared surface beforehand came into contact with the overflow of the zinc.

A wiper means such as element 100 may be provided in outlet 86 to regulate the thickness of the zinc coating without beading and to provide for the excess to be removed for return to the container while still in a molten state and still in a protective atmosphere. A similar element may be provided at the inlet Qk to engage the surface of the belt. These two elements may consist of guide blocks shaped so that they conform to the surface of the belt and they can be constructed of materials to which molten zinc will not adhere. An alloy of tungsten and aluminum have been found useful for this purpose.

After the element 84, the band surrounds a line, which with Outlets are provided to provide a sharp flow of warm air to be added so that excess zinc is removed and in this way the thickness of the zinc coating is regulated,

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a gloss finish is provided and uniformity of the coating is ensured.

As seen in Figures 2 and 3 _o to. is seen, the strip 2 enters the bath of molten zinc in the trough 52 below the level of its surface Ϊ02. As it passes through the bath, it runs in the same horizontal plane and exits in a similar manner. This electroplating process has many advantages. The most important advantage is a complete, high quality coating on all surfaces, including the edges of the strip. As noted above, with such a treatment it becomes possible to continuously galvanize steel strips which are normally slit on a wide coil material, the thickness of which is greater than 0.036 inches (about 0.092 cm) and produce a product which is corrosion resistant, including rust on all exposed surfaces and including the edges and sides of punched holes, for periods longer than previously possible. In addition, a bare, smooth end product is obtained which is free from defects such as ζ · Β »shrinkage or stains in places where the galyanization is incomplete.

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It appears that there are a number of reasons why these results are obtained. First is, by entering in the electroplating bath below the level of its upper one Surface, the strip material is constantly exposed to fresh bath material, since it does not have to pass the slag which forms on the surface of the baths, as it used to be. Second, the constant circulation brings one good dispersion through the entire bath of each alloy material, which can be used. Furthermore, regulation is easier due to the optimal circulation temperature the temperature reached, and a better ability to keep the bath at the desired temperature »

Another advantage is that foreign bodies can be removed more easily, which are to the surface of the bath rise, and debris that are heavier and on falling the ground. Veiter, the length of the trough 52 is advantageous can be regulated · So far, this has been done by means of additional guiding principles in the railroad or through Providence made deeper baths. It is also made easier to keep the continuous plating line in operation because it is no longer necessary to wind the tape over guide rollers into the tape

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As described above, the method and apparatus can be used to continuously electroplate flat strips by using form and return rolling o It is possible to electroplate shaped or partially formed strip material at the same time. Thus, in Fig. 7 an alternative embodiment is illustrated according to which the belt 2 after exiting the housing k & and after the quenching or cooling stage 5 ^ can pass through a series of forming rolls 102 to be shaped into any desired shape, such as Z ₀ B ₀ as rectangular sections or angled constructions · After the molding process, a pair of scissors can be provided to cut the molded tape to the desired length «

Fig. 8 illustrates a shaped belt which is continuous Can be electroplated by the process and using the device according to the present invention. This is a more complicated form and sets Tape, which has two curves 108 and 110 that can be used as safety barriers as they do be installed along highways. In this case the device could have a punch at one point which is located before the surface preparation stages to To punch holes 112 in the groove ll4 through the dop-

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pel curve of such a band is formed. This punch could be provided prior to the forming step so that the holes are in the formed strip prior to electroplating. This arrangement allows excess zinc in trough 11A to drain off the sloping sides of the curves to re-enter the bath and at the same time the sides of holes 112 are plated to provide corrosion protection. An alternative is that the pre-cut tape could be used if it is the form to be electroplated by means of the method and apparatus according to the present invention according to FIGS. 9A and 9B .

Fig. 9-B illustrates the desired end product, ie a rectangular piece II6, all of the exposed surfaces of which are electroplated. Such a shape could be formed by the belt material is first partially formed into the position shown in Fig. 9 ^A angular shape IL8, and then preparing the tape in this form in the same manner as described above passes through the electroplating bath. After electroplating and cooling, additional forming rollers could complete the manufacture of the belt II8 into the right-angled shape II6.

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If you want to galvanize smooth tape, which is rolled up for further processing at another point must be, so can a loop, such as the one designated by 10 in the upper part of the device between the scissors 66 and take-up reel 68 users will be able to create a to enable continuous operation. The working of such a loop would provide a repository for Provide galvanized tape while an empty roll is replaced by a roll that has just been filled «

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Claims (1)

- 26 claims. I, J A method of continuously electroplating steel strip, characterized in that steel strip is continuously fed from a source of material that while moving in a horizontal plane into a fluidized bath of molten zinc, the strip is fed to a location below the upper surface thereof that the tape moving through the bath is kept in the same horizontal plane, and that the tape, as it moves out of the bath of molten zinc in the same horizontal plane, is guided to a point below the surface of the same. 2. The method according to claim 1, characterized in that that the surface of the tape is prepared by washing it off before it is introduced into the bath and is stripped. 3. The method according to claim 1, characterized in that that the tape is preheated before entering Ln the bath. 109820/1347 4. The method according to claim!, Thereby geken nzeicbnet » that the tape is shaped so that it has downward sloping sides before it goes into the Bath enters. - 5. The method according to claim k , dadurchgeke η η-z e ic h η et that the tape is reshaped so that ea is flat after its exit from the bath. 6. The method according to claim I ₁ characterized geken nz eich η et that the tape is partially formed into the desired shape before it rode ίη the bath 7 · Method according to claim 6. ei ai -. : α tr eke r < · '■ - indicates that the partial e x ^ fovvol - .O ₁ . ., α ·,: ^ '■'^; · The desired shape is formed after s, - a ^ i? stepped out of the bathroom ... 8. The method according to claim 1, represents! ? nzeichnet rch geken that the "and J. e" vi? I run moving bath of molten zinc is _a soft non-oxidizing atmosphere in a maintained " 109820/1347 9 _t A device for carrying out the method according to claims 1 to 8, characterized by means for continuously supplying steel strip to the apparatus, means for pre-heating the strip to a temperature suitable for coating with molten zinc, means for applying molten Zinc on the surfaces of the preheated metal strip, and means for feeding the strip into the zinc application device, one surface of the strip being inclined to the horizontal 10. The device according to claim 9, characterized in - .., z \ β rejects that the feed device is a device for shaping the strip in a shape with inclined sides · ₍ 11 · Device according to claim 10, characterized. indicates that the forming device is a roll forming device to give the strip an arcuate shape To give shape 12 · Device according to claim 10, characterized in that the shaping device consists of a Roll forming device is made to give the belt an angled To give shape 109820/1347 ι * Blank page ; y _r K