US3592160A

US3592160A - Retractable snout for metallic coating process and apparatus

Info

Publication number: US3592160A
Application number: US50476A
Authority: US
Inventors: Roman A Schwieterman; Kasimir Oganowski
Original assignee: Armco Inc
Current assignee: Armco Inc
Priority date: 1970-06-29
Filing date: 1970-06-29
Publication date: 1971-07-13
Anticipated expiration: 1988-07-13

Abstract

Snout for metallic coating line extending from the strip preparation furnace to the coating metal bath, having a gas impermeable flexible joint permitting movement of the snout from a position with one end immersed in the coating bath to a position thereabove, permitting a change in coating metal bath or coating metal bath and container without degassing the strip preparation furnace.

Description

United States Patent inventors Appl. No, Filed Patented Auignee RETRACTABLE SHOUT FOR METALLIC COATING PROCESS AND APPARATUS 12 Claims, 5 Drawing Figs.

u.s. C1. 118/65, 118/419, l18/423,118/503,277/135 lnt.C1. B051: 11/12 Pleldolsenrcli 118/423- Primary Examiner- Morris Kaplan Anorney-- Melville, Strasser, Foster and l-lofi'm an ABSTRACT: Snout for metallic coating line extending from the strip preparation furnace to the coating metal bath, having a gas impermeable flexible joint permitting movement of the snout from a position with one end immersed in the coating bath to a position thereabove, permitting a change in coating metal bath or coating metal bath and container without degassing the strip preparation furnace.

PATENTEDJUUBISYI 3,592,160

SHEET 1 OF 2 F lG-l FIG-2 lNVENTOR/S ROMAN A. SCHWIETERMAN 8 KASIMIR OGANOWSKI,

BY 44;; gwgzw ATTOR NEYS PATENTEU JULIBISYS 3,592 160 SHEET 2 BF 2 INVENTORES ROMAN A. SCHWIETERMAN 8| KASIMIR OGANOWSKI,

ATTORNEYS RETRACTABLE SNOUT FOR METALLIC COATING PROCESS AND APPARATUS CROSS REFERENCE TO RELATED APPLICATION This is a division of application Ser. No. 859,033 filed Sept. l8, I969 in the names of Schwieterman and Oganowski, now U.S. Letters Patent No.

BACKGROUND OF THE INVENTION This application relates to a continuous metallic coating operation wherein a ferrous base metal strand is conducted through a strip preparation furnace, and then, in a protective atmosphere through a down turned snout into a bath of molten coating metal. Exemplary commercial procedures now in widespread commercial use are described in U.S. Pat. Nos. 3,320,085 in the name of Turner and 3,396,95l in the name of Cope et a]. The former contemplates a strip preparation furnace utilizing carefully controlled temperatures and furnace atmospheres to achieve nonoxidizing surface cleaning by gas. The latter, while particularly directed to a procedure for preventing excessive strip oxidation during line stops, describes a modification of the so-called Sendzimir process, wherein the surface of the strip is prepared to receive a molten metal coating by successive heat treatment in an oxidizing and then a reducing atmosphere.

In either case, a down turned snout is provided at the end of the strip preparation furnace, one end of which is normally disposed beneath the surface of the molten coating metal. This snout serves to maintain a protective atmosphere about the cleaned strip until it comes into contact with the coating metal.

This invention is directed primarily to the problem of changing a given coating line from one metallic coating metal to another by changing the bath and/or container. Reference is made to U.S. Pat. No. 3,130,068 in the name of Whitley which describes in detail many of the problems associated with the changeover in coating metals. According to this patent, the changeover is accomplished by rapidly pumping the coating metal out of the coating pot and into a holding pot, removing the coating machine (pot roll and finishing rolls) and coating pot, placing a new coating pot in position, and finally pumping the new coating metal into the new pot.

In addition, as explained in that patent, the heating furnace and down turned snout are normally filled with a reducing gas, such as hydrogen. During the course of the coating metal changeover, the entire furnace has to be degassed to eliminate the danger of explosion when the lower end of the snout is no longer immersed in the coating metal.

SUMMARY OF THE INVENTION The instant invention, in its broadest aspect, contemplates a gas impermeable flexible joint associated with the down turned snout and permitting movement of the snout from the position wherein its lower end is immersed in the coating metal bath to a position thereabove.

The gas impermeable, flexible joint just referred to can take many specific forms, two of which are described in more detail hereinafter.

Once the coating machine is removed in a conventional manner, the snout is raised to a position above the coating pot, and the strip can be drawn up snugly against the lower end of the snout, which of course means that the entire strip will be above the top of the coating pot. This will permit the original coating pot to be moved horizontally out of position, and a new pot moved into position.

The invention also contemplates the provision of a pair of battles mounted within the snout, these baffles preferably being movable to a position substantially closing the open end of the snout so that degassing of the entire strip preparation furnace can be eliminated.

DESCRIPTION OF THE FIGURES FIG. 1 is a schematic view of the end of a continuous coating apparatus including the down turned snout and the coating pot in the normal operating position.

FIG. 2 is a schematic diagram similar to FIG. 1 showing the snout in the retracted position.

FIG. 3 is a schematic diagram of the end of a coating apparatus showing a modified snout arrangement in the normal operating position.

FIG. 4 is a schematic diagram similar to FIG. 3 showing the snout in the raised position.

FIG. Sis a schematic diagram showing a modified liquid seal retractable joint.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 1, the end of a conventional strip preparation furnace is indicated at 10, and the strip being coated is shown at 12. It will be seen that securely fixed to the end of the furnace I0 is the down turned snout indicated generally at 14. It will be observed that the lowermost end of the snout is immersed below the surface 16 of molten coating metal contained in the pot 18.

The strip 12 passes through the furnace 10, over the turn down roll 20, through the snout I4, and into the bath of coating metal. It then passes under the pot roll 22 submerged in the bath and emerges from the bath in a generally vertical path of travel. It will of course be understood that suitable apparatus will be provided for finishing the molten coating metal as the strand emerges. Such apparatus might include exit rolls, jet nozzles, or the like, all of which are now known in the art.

The snout 14 shown in FIG. I includes the fixed portion 24 which is secured to the strip preparation furnace l0, and the retractable portion 26. The joint between these portions has several very important requirements. According to this invention, it must be flexible or retractable so that the portion 26 of the snout is movable from the normal operating position immersed in the coating metal to the position shown in FIG. 2 wherein it is spaced above the coating pot. In addition, the joint must be gas impermeable.

That is, as explained earlier, the strip preparation furnace l0 and snout I4 will be charged with a reducing gas such as hydrogen. These reducing gases will be introduced into the apparatus in the region of the snout and travel countercurrent to the strip through the strip preparation furnace. In order to eliminate the risk of fire and explosion, it is most important that the flexible joint between the fixed portion 24 and the retractable portion 26 of the snout be gas impermeable.

In the embodiment shown in FIGS. I and 2, the gas impermeable, flexible joint is formed by providing the annular cavity 28 around the upper end of the retractable portion 26 of the snout. This annular cavity contains, at its bottom, heating means indicated schematically at 30, and is adapted to be filled with a low melting point metal or alloy having little tendency to vaporize at coating temperatures. Since some vaporization may occur, the metal or alloy selected should be one which will not adversely affect the molten metallic coating. Lead and the alloy Woods Metal are exemplary of those which may be used with success. The lower or free end of the fixed portion 24 of the snout is received in the annular cavity and immersed below the surface of the molten liquid carried by the cavity.

It should therefore be apparent that relative movement between the

portions

24 and 26 of the snout can be accomplished, and the joint will be gas impermeable so long as the lower edge of the fixed portion 24 is below the surface of liquid in the cavity 28.

It will of course be understood that suitable means will be provided for raising the retractable portion 26 of the snout from the position shown in FIG. 1 to the position shown in FIG. 2. Such lifting means may take any desired form, and do not, per se, form a part of this invention.

In order to change coating pots with the apparatus just described, the strip would be stopped, the coating equipment including the pot roll 22 and the finishing apparatus would be removed, the retractable portion 26 will be moved upward to the position shown in FIG. 2, the strip will be pulled out ofthe bath and into a snug position about the retracted snout, the original coating pot moved horizontally out of the way, and the new coating pot moved into position. The above steps are then reversed and the coating operation with a new or different coating metal may be commenced.

It will be apparent to the skilled worker in the art that once the lowermost end of the snout is taken out of the coating metal bath, it will be possible for air to enter the snout and strip preparation furnace. The existence of the hydrogen or other reducing gas in these components at elevated temperatures presents a great risk of explosion, and hence the prior art has always found it necessary to degas the furnace before the seal between the snout and the bath is broken. This degassing may be accomplished by shutting off the supply of reducing gas, opening an auxiliary port, and burning the reducing gases as they issue from the port. Alternatively, the furnace can be degassed by purging with nitrogen or some other inert gas.

As seen in FIGS. l and 2, the snout 14 includes the pivotally mounted

baffles

32 and 34. It will be seen that these baffles are each pivotally movable from the position shown in FIG. 1 wherein free passage of the strip 12 is permitted, to the position shown in FIG. 2 wherein these baffles in effect clamp the strip being coated against a sidewall of the snout. By means of these baffles, it is possible to eliminate the step of degassing the furnace.

When these baffles are provided, the upper baffle 32 is closed and nitrogen or other inert gas is introduced into the snout in the region between the baffles. An auxiliary port may be provided between the baffles to burn out the gases therein. The lower baffle 34 is then closed. The inert purging gas is continued in the region between the baffles at a pressure higher than that of the furnace in order to insure that any leakage is into the furnace and not the other wayv At this time, the lower end of the retractable portion 26 of the snout can he raised from the coating metal bath. The higher pressure region between the baffles again insures that any gas flow is out of the snout and not the other way. In other words, this higher pressure region prevents mixing of the reducing gas in the furnace l and atmosphere via the open end of the snout portion 26, thereby eliminating the hazard of explosion.

The concept of utilizing two baffles and a supply ofinert gas therebetween does not depend on the pivotal baffles shown. The invention may be practiced by utilizing two restrictive baffles in the snout and a sufficient supply of inert gas to insure that there is no leakage out of the strip preparation furnace.

Since the lowermost end of the retractable portion 26 of the snout has been immersed in the coating metal, it may be necessary to change this portion of the snout when changing coating metal pots to avoid contamination of the coating metal. This may be accomplished by severing the strip adjacent the lower end of the retractable portion 26 of the snout, and simply removing this portion of the snout. When a new portion 26 is in place, the strip can be welded together at the severed point, and the operation can be continued.

FIGS. 3 and 4 illustrate diagrammatically a slightly different embodiment of this invention. As seen in these figures, a gas impermeable flexible bellows joint 44 is provided adjacent the end of the snout which is secured to the reducing furnace 10. A joint of this character will permit pivotal motion at this point, thereby in turn permitting the lower end of the snout to be raised upwards out of the coating metal pot.

The baffle construction according to this embodiment is substantially the same as that shown in H08. 1 and 2, and has been identified with similar reference numerals.

While not shown in the drawings, it will be apparent that the lower end of the snout (that portion immersed in the coating pot) may be formed as a separate element, suitably joined to the remainder of the snout in order to facilitate its removal when changing coating metal. In this event, the change can be accomplished as indicated earlier. That is, the strip can be severed and the lowermost portion of the snout removed, or the lowermost portion can be formed in two halves which may be removed without severing the strip.

FIG. 5 schematically illustrates an alternative form of a retractable, gas impermeable joint utilizing a liquid seal. According to this embodiment, the annular molten liquid containlng cavity 46 is formed as a separate unit. The upper end of the retractable portion 26 of the snout (shown in the raised position), and the lower end of the fixed portion 24 of the snout are provided with the

mating sealing flanges

48 and 50 respectively, each of which are immersed in the liquid contained in the cavity 46. This embodiment has the advantage that when changing snouts, the annular cavity 46 need not be emptied ofits molten sealing metal.

it is believed that the foregoing constitutes a full and complete disclosure of this invention. arious modifications can be made without departing from its scope and spirit.

The embodiments of the invention in which an exclusive property or privilege we claim are defined as follows:

1. In apparatus for coating a strand with a molten coating metal including heating means arranged for the passage of said strand therethrough, a bath of molten coating metal, and a snout secured to said heating means and having a portion normally immersed in said bath, the improvement which comprises: means associated with said snout and permitting movement of said portion of said snout from said position normally immersed in said bath to a position thereabove, restrictive baffle means adjacent each end of said snout, and means including a supply of inert gas under pressure intermediate said baffle means for eliminating explosive gasses therefrom.

2. The improvement claimed in claim 1, wherein said baffle means is movable from an inoperative position permitting sub stantially unrestricted passage of said strand thereby to a sealing position.

3. The improvement claimed in claim 2 wherein said sealing position of said baffle means is effective to force said strand against a side of said snout.

4. ln apparatus for coating a ferrous strand with a molten coating metal including heating means, a bath of molten coating metal, and means for moving said strand in succession through said heating means and bath, the improved apparatus comprising:

a. a snout arranged for the passage of said strand therethrough from said heating means to said bath, said snout having a first portion secured to said heating means and a second portion normally immersed in said bath, and including a gas impervious joint between said first and second portions;

b. roll means in said bath about which said strand passes, said roll means being spaced from the portion of said snout immersed in said bath;

c. means for moving said second portion of said snout with respect to said first portion to a position spaced above said bath; and

d. means operative when said roll means is removed, to

draw said strand against the free end of said second portion to a position above said bath so that said bath of mol ten coating metal can be changed.

5. The improved apparatus claimed in claim 4 wherein said gas impermeable joint comprises a liquid seal joint.

6. The improved apparatus claimed in claim 4 wherein said gas impermeable joint comprises a liquid filled annular container means associated with said second portion of said snout; and annular means associated with said first portion and received in said liquid filled container means.

7. The improved apparatus claimed in claim 6 including heating means associated with said annular container means.

8. The improved apparatus claimed in claim 4 including spaced apart baffle means disposed within said snout.

means is movable from an inoperative position permitting substantially unrestricted passage of said strand thereby to a sealing position.

12. The improvement claimed in claim ll wherein said sealing position of said baffle means is effective to force said strand against a side of said snout.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 59 Dated y 13 J 97 Invenwfls) Roman A. Schwieterman; Kasimir Oganowski It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 9, following the phrase" U.S. Letters Patent No. insert 3,551,185

Signed and sealed this 7th day of March. 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. Attesting Officer ROBERT GOTTSCHALK Commissionerof Patents RM PO-1050 1 USCOMM-DC 60376-F69 fl- U75. GOVERNMENY PRINTING OFFICE L 1989 0-366-331

Claims

2. The improvement claimed in claim 1, wherein said baffle means is movable from an inoperative position permitting substantially unrestricted passage of said strand thereby to a sealing position.

4. In apparatus for coating a ferrous strand with a molten coating metal including heating means, a bath of molten coating metal, and means for moving said strand in succession through said heating means and bath, the improved apparatus comprising: a. a snout arranged for the passage of said strand therethrough from said heating means to said bath, said snout having a first portion secured to said heating means and a second portion normally immersed in said bath, and including a gas impervious joint between said first and sEcond portions; b. roll means in said bath about which said strand passes, said roll means being spaced from the portion of said snout immersed in said bath; c. means for moving said second portion of said snout with respect to said first portion to a position spaced above said bath; and d. means operative when said roll means is removed, to draw said strand against the free end of said second portion to a position above said bath so that said bath of molten coating metal can be changed.

9. The improvement claimed in claim 8 including means intermediate said baffle means for eliminating explosive gases therefrom.

10. The improvement claimed in claim 9 wherein said means intermediate said baffles is a supply of inert gas under pressure.

11. The improvement claimed in claim 8 wherein said baffle means is movable from an inoperative position permitting substantially unrestricted passage of said strand thereby to a sealing position.

12. The improvement claimed in claim 11 wherein said sealing position of said baffle means is effective to force said strand against a side of said snout.