US2310162A - Apparatus for galvanizing - Google Patents

Description

Patented Feb.' 2, 41941-5 APPARATUS ron oanvmzme Elwin A. Matteson, Youngstown, Ohio, assignor to The Aetna Standard Engineering Company,

Youngstown, Ohio, a corporation of Ohio Application'November z5, 1939, serial No. 306,156

. 1 claim. (o1.

l This invention relates to the artv of metal coat-A ing and more particularly to' certain improve-i ments in apparatus for galvanizing, i. e., coating with zinc, steel sheets or strips.

In the galvanizing of steel or ironv sheets or other articles it has been a common procefdurelto en -12.5; ow is not seriously interfered with by the presence of a Sheet or `strip'in the bath; the pro-,

. visionof a dross skimming and collecting mecha- -nism 'which may be applied to the usual galpass the sheets into and througha pot or. tank f of molten zinc to effect the bonding of a layer of pure zinc to all surfaces of the work. A

modification of this general procedure is to establish and maintain a pot of molten lead 'and float upon a portion of the surface of the ppt of lead a layer or pool of molten zinc. The sheets are caused to enter and pass through the lead bath which brings them up to the proper temy perature and they are then withdrawn through vanizing pot and which is adapted to be driven" from the same powerv source as the exit rolls of the galvanizing machine; the provision of means for skimming dross from a galvanizing bath which `is effective regardless of reasonable variations in the dross level in the bath; the provision of means for creating and maintaining a positive flow of dross in a lead-zinc galvanizing bath at all times during the passage of material through the bath;v the provision of an eiective and rugged apparatus, for improving and rendering more uniform the zinc coating applied by a' galvanzing machine.

The above and other objects of my invention I will appear from the following description of a preferred embodiment thereof, reference being had to the accompanying drawings, in'whichof molten zinc and also achieves a better zinc coating because the pre-heated sheet is only subjected to contact with the zinc for a relatively short period and thus the alloy layer between the steel and zinc is kept to a minimumthickness. As this alloy layer is relatively brittle it is advantageous, particularly where the sheets are to be bent or formed after galvanizing, to maintain it as thin as possible.

In the galvanizing of ferrous metal articles dross is formed as the Work passes through the zinc bath. alloy of zinc and iron, together with certain other impurities, and is heavier than zinc but lighter This dross is composed largely of an` Figure 1 is a plan view of a galvanizing pot and machine equipped with my invention.

Figure 2 -is a vertical cross-sectional View of the galvanizing equipment shown in 'Figure 1,

taken substantially on line 22 of lFigure 1.

. Figure 3 is a transverse' vertical cross-sectional view taken on line-33` of Figurey 1, showing one of the dross moving screws.

Figure 4 is a simplified illustrative vertical cross-sectional view of'my improved galvanizing apparatus taken substantially on line l-I of Fig-b ure 1, but omitting numerous parts of the structure in orderv more clearly to show the arrangethan lead. In the operation of a galvanizing upon the lead. In order to permit satisfactoryl continuous operation this dross must be removed. As the operator is unable to see and gauge this lead, thedross settles down tothe junction or', I

ment of certainfeaturesofmy invention. z-

' Figure 5 is a diagrammatic cross-sectional view, ona reduced scale,t aken on line, 5-5 of Figure '4 and showing the Vldispositionof the lead and zinc 1n the pot..

The tank or pot I has anopen top and supports thespaced vertically extending frame members 2' and 3 which arrfconnected together by lead-zinc level, the removal of this drosspre-f sents a rather dimcult problem, and it is among' the objects of my invention to provide a simple and eifective apparatus for continuously removsuitable cross members such as therods l, the

ends of which are secured to the side `frame meming dross from the lead-zinc level of a gal vanizing bath, which apparatus is effective reproved dross skimming apparatus.

gardless of reasonable variations in the leadl ive ilow of drossv into this compartment which bers 2 andY 3'by nutstisee Fig. 2). The machine frame structure so" formed supports the sheet feeding mechanism and also carries my im- 'I'he ventire assembly makes up a galvanizing machine -or unitwhich may b e lifted bodilyfrom the pot I when so desired.-

The mechanism'for feedingthe steel sheet or strip through themetal-bath' 1n the pot I may be of any'suitable form :andnin the illustrated structure itv includes a pair'of entering rolls gears I6 and I1. 'Ihe roll 1 is connected through a coupling I8 to the power source and the shaft of the roll I2 carries a gear I9 meshing with a gear 2U which is also connected to the power source. 'I'he bottom roll II is provided with a worm gear 2l meshing with a worm 22 on the lower end of the drive shaft 23. The upper end of shaft 23'. carries a bevel gear 24 which is driven by a corresponding bevel gear 25 from the power source. Any suitable means may be` provided for synchronizing the speeds of the three sets of rolls but, as this forms no partr of the present invention, it is not illustrated or described herein. Furthermore, as vthe details of the roll supports, etc., are not involved -in the present invention they need not be specifically described in great detail, but reference is made to the co-pending application of Elwin A. Matteson and Benjamin P. Finkbone, Serial No. 200,486,

filed April 6, 1938, now Patent No. 2,183,890, is'

sued December 19, 1939, which fully illustrates and describes a similar arrangement of feed rolls and associated parts.

'Ihe usual iiux bo'x 28, which maybe a walled structure open at the top and bottom, is disposed just below the entering rolls 8 and 1 and the walls extend from above the bath level down into the molten metal. A baille or mud wall 2'Iv extends entirely across the pot I and extends of the molten metal. 'Ihis wall 21, as will more fully appear later, serves to separate the zinc pool from the body of molten lead in the pot and thus reduces the quantity of zinc required to be maintained in the pot.

As is best seen in Figure 4, the pot is substantially filled with molten lead indicated at 28 and a relatively small pool of molten zinc 23 is maintained at the exit end of the pot and prevented from spreading over the entire surface of the molten lead by the wall 21. As zinc is lighter than lead the zinc-lead level or junction 30, which cannot be observed by the operator, may be maintained by properly maintaining the visible zinc level 3I and visible lead level 32 in accordance with predetermined gauge marks or other indicating means. The zinc level 3l is above the lead level 32 and is preferably maintained substantially on the center line of the exit rolls I2 and I3.

At one end of the zinc pool, which is malntained at the exit end of the pot I. is a dross sump structure best seen at 33 in Figure 3. This sump is a separate compartment from the main pot I and, although it is shown on the drawings as being a structure extending beyond the main side wall of the pot I, it will be understood that it might be incorporated within the walls of the pot if so desired. A dross outlet pipe 34 extends from the bottom of the sump 33 to any suitable place of disposal and is provided with shut-off means such as atvalve (not shown) to prevent flow of material from the sump 33 except when it `is desired to withdraw dross therefrom. The inner wall 35--of the sump 33 extends up to the normal lead-zinc level and forms a dam preventing the entry of lead into the sump 33. Ihe

I down from the top thereof well below the level cated in Figures 3 and 5 and the lead-zinc level or dross line 30 will not extend into the sump 33 but will stop at the wall 35.

It will be observed by referring to Figure 4 that, when sheet or strip material is passed through the molten metal in the pot I by means of the rolls 6 1, Ill-II and I2-I3, it will rst be heated to the desired temperature as it passes through the lead bath 28. Then, as it enters the zinc pool 23 through the lead-zinc level 30 and passes out through the exit rolls I2 and I3, it will be given the desired zinc coating. 'I'he galvanizing operation causes the formation of dross in the zinc bath 29 and this dross will settle down to the lead-zinc level 30 where it will float upon the surface of the lead. It is important to prevent the accumulation of dross at this level as it seriously interferes with successful coating of the work. In order positively and effectively to prevent the accumulation of dross at the leadzinc level 30v I provide a pair of conveyor or feed screw members 36 and 31. These are disposed with their axes substantially at the' lead-zinc level 30, the screw 36 being on 'one side of the path of the work through the zinc bath and the screw 31 being on the other side thereof. In the illustrated embodiment of my invention these screws 36 and 31 are of opposite hand and rotate in opposite directions, thus moving the dross toward and into the sump 33.

The driven gear I3 on the exit roll I2 drives a gear 38, suitably supported on the frame 2, which in turn drives another gear 33. I'he shaft which carries the gear 33 also carries a sprocket 40 and a chain 4I drives the screw 36 through "a suitable sprocket 40 mounted on the end of the screw shaft 42.

In like manner, a driving connection is established to the shaft of the screw 31 through a chain 43 and suitable sprockets 43' and 43" connected to the gear 39 and the screw shaft 31' respectively.

The above described driving hook-up for the screws 36 and 31 will result Yin opposite rotation of the screws and therefore the screws are made of opposite hand in order to cause a feeding ac tion or flow of the material in the lead-zinc level 30 in a direction toward the dross sump l 33. If desired both screws could, ofcourse, be

made the same hand and rotated in the same direction.

' As is best seen in Figure 3, the shaft 31' of the screw 31 is supported in one end in a bearing 44 carried by the frame member 2. 'I'he frame 3 is provided with a suitable aperture 45 through which the screw 31 extends. The screw shaft 31' just clears the top of the inner wall 35 of the dross sump 33 and this wall is preferably notched adjacent .the shaft 31' so that the wall 36l will extend up to about the center line oi' the shaft 31. A bearing bracket or hanger 46 is suspended on a projecting arm 41 mounted on the frame 3 and this bracket 46 ,carries a bearing 48 which supports the other end of the screw shaft 31' sump 33 will be lled with molten zinc as indi- 75 lwithin the dross sump 33. i

The screw 36 and its shaft 42 are similari mounted and a suitable aperture is provided in the wall 3 for the screw 36. This aperture may be an elongated slot or a series of holes may be pro# vided so that the dross iiow or movement, established by rotation of the screws 36 and 31, in a direction across the bath toward the sump 33 will not be seriously interferred with by the wall 3. It will beunderst'ood that rotation of the screws 36 and 31 will set up a iiow of dross not only within the radius of the screws themselves but also for dl'ODS 'in the sump 33.

- bath, will pass over the top of the wall 35 into the dross sump 33, which as noted above is lled entirely with zinc. After the dross passes across the wall 35 it will sink through the zinc to the bottom of the sump 33 because the dross is heavier than the zinc. When a sulcient quantity has collected in the bottom of the sump 33 it may be drawn on through the outlet 3l. Any zinc which may come oil with the dross can be separated therefrom and returned to the bath; The sheet or strip passes upwardly between the two screws 33 and 31 and the now of dross transversely to the direction of movement of the sheet is not interfered with in any way by the sheet. Moreover, by

providing a pair of feed screws 33 and 31, the

dross which is formed and collects at the leadzinc vlevel on both 'sides'. of the -sheet path is removed.

Even though ofz the wall 35 the screws-36 and 31Awi1l still be 4effective so long as the level does not vary more the lead-zinc level- 30 may lvary materially in a downward direction from the top form of my invention, it will be seen thatl have provided 'a simple and effective apparatus in which the work is passed through a lead bath and then upwardly through a layer of zincvfioating on the lead and in which the dross is moved transversely of the directionI of movement of the work and positively removed from the bath. Thus,

the galvanizing operation can be carried out rapidly and the quality of the work improved.

Although I have described the illustrated apparatus in considerable detail, it will be understood ,Y

by those skilled in the art that variations and mbdincations may be made in the same without lead-'zinc level 33, which cannot be seen by the operator, with extreme accuracy as normal variations willnot interfere with-the effective removal of the-dross. If the lead-zinc level 30 low .the top of the wall 35 the dross will merely build up against the wall 35, due to the action of the screws 31, and, as the screws oo n-l tinue to rotate, will be pushed on over the wall,

into the .sump 33. Care should. of course, be taken to prevent the lead level from rising above the level of the top of the wall 3i so that the lead will not ilow into the sump 33, although, in case thisshould happen, it can be readily correctedby .lowering the lead level to the proper position and then drawing ot! any lead which has accumulated From the foregoing description ofa preferred departing from the spirit of the invention. I do not, therefore, wish to be limited to the particular embodiment of my invention shown and described, but claim as my invention all forms thereof coming within the scope of the appendedv claim. Y

Reference is hereby made to my divisional-'L application, Serial No. 456,891, filed September l,

194g, for Method of galvanizing, and containing claims directed tothe method disclosed in this application.

I claim: In apparatus Lof the type described, a galvanizing p ot, entering rolls for feeding -metal sheets or the like into said pot, exit rolls for removing 'sheets from said pot, a dross sump disposed on one side of said pot adjacent oneend of said 'exitrolls,

communicating means'between said sump and pot below the top edge of said sump and pot, a baille extending across said pot between said entering y and exit rolls-and-generally parallel thereto, said', .baille having a lower edge above the bottom of said pot, a pair of feed screws extending generally parallel-to said exit rolls and disposedat substantially the level of said communicating means below and ofthe pass4 line between 'said exit for driving said feed screws inl p'roper direction to impart movement to materi'al in said pot toward said dross sump,

one on each side ELwIN A. MA'rrEsoN.

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