U.S. patent number 3,696,503 [Application Number 04/871,917] was granted by the patent office on 1972-10-10 for method for continuously galvanizing steel strip.
This patent grant is currently assigned to Allied Tube & Conduit Corporation. Invention is credited to Theodore H. Krengel, Arthur E. Ostrowski, Anthony J. Raymond.
United States Patent |
3,696,503 |
Krengel , et al. |
October 10, 1972 |
**Please see images for:
( Certificate of Correction ) ** |
METHOD FOR CONTINUOUSLY GALVANIZING STEEL STRIP
Abstract
A method of galvanizing strip steel is disclosed in which a
continuous strip moving in a horizontal plane, after passing
through preparation steps, is caused to enter a bath of molten zinc
below the level of the surface of that bath. The strip still moving
in a horizontal plane passes through the bath and exits therefrom
from a location below the surface. After cooling, the strip may be
coiled or partially roll-formed and cut to desired lengths. The
disclosure includes the steps of forming or partially forming the
strip prior to its entry into the bath.
Inventors: |
Krengel; Theodore H.
(Flossmoor, IL), Ostrowski; Arthur E. (Alsip, IL),
Raymond; Anthony J. (Olympia Fields, IL) |
Assignee: |
Allied Tube & Conduit
Corporation (Harvey, IL)
|
Family
ID: |
25358438 |
Appl.
No.: |
04/871,917 |
Filed: |
October 28, 1969 |
Current U.S.
Class: |
29/527.4; 72/47;
427/329; 427/367; 427/369; 427/432; 427/434.5; 427/543; 427/172;
427/360; 427/398.3; 427/433; 427/436 |
Current CPC
Class: |
C23C
2/38 (20130101); C23C 2/06 (20130101); Y10T
29/49986 (20150115) |
Current International
Class: |
C23C
2/38 (20060101); C23C 2/06 (20060101); C23C
2/36 (20060101); B23p 017/00 () |
Field of
Search: |
;29/527.1,527.4,527.2,527.3 ;72/47 ;117/130,131 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Campbell; John F.
Assistant Examiner: Rooney; Donald P.
Claims
What is claimed as new and desired to be secured by Letters Patent
of the United States is:
1. A method of continuously galvanizing steel strip comprising the
steps of:
continuously feeding flat steel strip from a source of such
material;
passing the strip with all of its surfaces exposed, whereby all of
said surfaces will be galvanized while moving in a horizontal plane
into an agitated bath of molten zinc at a location below the upper
surface thereof so as to avoid passage through any dross on the
surface of the bath and to produce a zinc coating substantially
free from flaws;
maintaining the strip moving through the bath in the same
horizontal plane; and
passing the strip while moving in the same horizontal plane out of
the bath of molten zinc at a location below the surface
thereof.
2. The method of continuously galvanizing steel strip as set forth
in claim 1 in combination with the step of preparing the surface of
said strip by washing and pickling prior to its passage into the
bath.
3. The method of continuously galvanizing steel strip as set forth
in claim 1 in combination with the step of preheating the strip
prior to entry into the bath.
4. The method of continuously galvanizing steel strip as set forth
in Claim 1 including the step of forming said flat strip so as to
have downwardly sloping sides and exposed edges prior to its entry
into the bath.
5. The method of continuously galvanizing steel strip as set forth
in claim 4 in combination with the step of reforming the strip so
as to be flat after its exit from the bath.
6. The method of continuously galvanizing steel strip as set forth
in claim 1 in combination with the step of partially forming said
strip to a desired configuration with exposed edges prior to its
entry into the bath.
7. The method of continuously galvanizing strip steel as set forth
in claim 6 in combination with the step of forming the partially
formed strip to a desired configuration after its exit from the
bath.
8. The method of continuously galvanizing steel strip as set forth
in claim 1 wherein the strip is passed into an agitated bath of
molten zinc maintained in a non-oxidizing atmosphere.
Description
The galvanizing of flat strip has been accomplished in the prior
art with which we are familiar by the use of baths or tanks of
molten zinc of substantial depth. The strip is fed into the bath by
causing it to enter its top surface from above and after passing
over one or more guide rolls to exit from the bath from the top
surface. With this basic apparatus and method satisfactory results
using appearance, resistance to rust and corrosion, as criteria
have been achieved. The strip steel galvanized is almost never a
finished product in itself but rather constitutes material to be
shaped into a desired configuration. In order to do this, it has
been the practice heretofore to galvanize strip material of fairly
large width and then slit the material. Usually, the slit material
is coiled and then transported elsewhere for shaping as by roll
forming, cutting or punching. When slit or cut or punched after
galvanizing, the side or other edges are exposed and when exposed
may rust. It is generally agreed that in order to achieve a product
which exhibits good resistance to edge rusting over long periods of
time there is a limitation on the thickness of the material that
can be galvanized. For instance, in one report of tests by Frank J.
Cole of the Republic Steel Corp. in Cleveland, Ohio, delivered at a
meeting of The Galvanizers Committee in October of 1963, it was
concluded that the degree of protection afforded by zinc
galvanizing was dependent on steel gauge and zinc thickness. In his
report, he stated that it was the usual view of the industry that
galvanic cathodic protection will protect the edges of galvanized
steel on only 0.036 inch. gauge and lighter and that his data
confirmed that view.
In considerable measure, the prior art method is necessary because
it has not been considered practical to shape strip material either
partially or completely in a galvanizing line. One reason is that
the length of the line required for the galvanizing methods of the
prior art are such that the addition of roll forming to the line
becomes uneconomical or otherwise not feasible.
Consequently, the generally accepted industry view has been, as
noted above, that 0.036 inch is the limit on the thickness of the
strip that can be galvanized in a continuous process where the
edges are exposed as slitting after galvanizing. When it is
possible, as is the case with this invention to eliminate the
slitting operation following galvanizing, to effect that operation
before galvanizing, then strip greater than 0.036 inch may be
galvanized and effective coating of all surfaces provided. This
result is obtained by an aspect of this invention which permits
strip material galvanized in a continuous process to be formed or
partially formed as by rolls, punches or the like so that a
finished or partially finished product with its exposed edges
galvanized is produced. Generally, roll forming of galvanized strip
is done up with strip up to 36 inches in width, and it is
contemplated that this invention may be used in continuous
galvanizing lines capable of processing strip of at least that
dimension.
Therefore, it is an object of this invention to provide a novel
method of galvanizing strip steel of any desired width so that the
edges will be adequately protected even with a strip thickness
greater than 0.036 inch.
Other problems of the prior art method and apparatus have the
effect of increasing their cost of operation by limiting their
flexibility as to the kind of strip that can be galvanized without
time consuming and expensive changeover procedures. Other cost
increasing factors are the need for periodic downtime for
maintenance of such elements, guides, sinker rolls and other
submerged moving parts. Further, it is necessary to periodically
remove dross on the top of the bath for instance. Also, complicated
means to maintain a desired bath temperature and dispersion of
alloying materials are required. In addition, if it is desired to
produce a galvanized steel product wherein the quality of the
surface finish is important, as for instance, where a consumer
product is desired, the use of post coating devices such as
planishing rolls is required thus further adding to the cost and
complexity of the system.
Accordingly, it is another object of this invention to provide a
novel method for the continuous galvanizing of strip steel which is
relatively easier and less costly to construct and maintain.
A further object of this invention is to provide a novel method for
the continuous galvanizing of strip steel which may more easily
than the prior art be threaded when it is desired to change from
one width of strip to another.
It is still another object of this invention to provide a novel
method for the continuous galvanizing of strip steel which is
capable of producing smooth spangle free finishes.
A still further object of this invention is to provide a novel
method for the continuous galvanizing of strip steel which will
coat strip material which has been roll-formed to a desired shape
or has been partially roll-formed before galvanizing and may be
finish roll-formed after galvanizing.
It is another object of this invention to provide a novel method
and apparatus for continuously galvanizing the surfaces of strip
steel which is not wasteful of the zinc used for galvanizing.
SUMMARY OF THE INVENTION
The above and other objects of the invention are achieved by a
novel method of strip galvanizing which includes the step of moving
the strip material in substantially a horizontal plane through a
zinc bath. In another aspect of the invention, the strip may be
processed while flat or partially formed.
BRIEF DESCRIPTION OF THE FIGURES
The subject matter which is regarded as the invention is
particularly pointed out and distinctly claimed in the concluding
portion of this specification. Embodiments of the invention, both
as to their structure and manner of operation, together with
further objects and advantages thereof may be best understood by
reference to the following description taken in connection with the
accompanying drawings in which:
FIG. 1 is a diagrammatic illustration of a machine embodying the
invention and useful in carrying out the method thereof;
FIG. 2 is a schematic illustration of a zinc bath structure useful
in carrying out the method of the invention;
FIG. 3 is a view along the lines 3--3 of FIG. 2;
FIG. 4 is a diagrammatic illustration of forming rolls forming a
part of a machine incorporating the invention and useful in
carrying out the method thereof;
FIG. 5 is an end view of strip material after it has passed through
the forming rolls of FIG. 3;
FIG. 6 is a diagrammatic illustration of reforming rolls which may
form a part of a machine embodying the invention and be useful in
carrying out the novel method thereof;
FIG. 7 is a diagrammatic illustration of a portion of apparatus
which may be used to practice an alternate embodiment of the
invention;
FIG. 8 is a perspective view of one type of steel strip that may be
galvanized in accordance with the invention;
FIG. 9A is a perspective view of a partially formed shape which may
be galvanized in accordance with the invention; and
FIG. 9B is a perspective view of the shape that may be formed from
the partially formed shape of FIG. 9A after galvanizing.
DETAILED DESCRIPTION
FIG. 1 illustrates a galvanizing machine which is fed with strip
steel 2 supplied from a strip reel 4. The machine is arranged as a
series of in line stages to operate in a continuous manner for
providing a galvanizing coat to all surfaces of the strip material
2. Advancement of the strip 2 is effected primarily by engagement
between the strip and the forming rolls rotating at relatively
constant speed whereby the strip is drawn into the machine for
processing. Since the lengths of the steel strip from the strip
reel 4 come to an end after a relatively short period of operation
by the machine and since the strip is taken up continuously by the
machine it its continuous operation, it is necessary to provide
means for splicing the end 6 of the strip from one reel 4 with the
leading end 8 of another reel for joinder of the strip into
continuous lengths without stoppage of the machine in its
continuous operation. For this purpose a loop 10 is taken in the
strip 2 and dimensioned to have a length sufficient to continuously
feed the strip to the mill while the trailing end 6 of the strip is
held stationary for splicing, as by welding, onto the leading edge
8 of a new reel which has been moved into a position for use. The
loop 10 may be placed about a roller riding on a carriage in turn
riding on a track similar to that shown in the U.S. Pat. to Krengel
et al. No. 3,122,114. To the same end a clamp 12 may be provided to
hold the end 6 while the end 8 is welded to it by the welder
illustrated diagrammatically by reference numeral 14.
Generally, it is necessary to trim or condition the edges of the
strip from the reel 4 for it is relatively rough and uneven. In
order to accomplish this edge trim or conditioning, means 15 may be
provided. This may be constituted by a rotary side trimmer which
removes a small portion of each edge or scarfing tools on each side
which will remove projections from the edges.
Likewise, prior to forming a slitter may be provided which cuts the
strip unwinding from the reel 4 into a plurality of strips, not
necessarily of the same width, which may then be processed
including forming, partially forming and galvanizing in parallel to
produce a product having all exposed surfaces galvanized.
In one embodiment of the invention in order to galvanize or coat
the surface of the strip 2 with zinc in accordance with this
invention, the strip is first passed through a series of forming
rolls 16 which have a configuration and number sufficient to form
the flat strip into an arcuate shape as shown in FIG. 5. By way of
illustration the forming rolls may be arranged through the machine
in the direction of the arrow 18. A first pair of forming rolls
engage the upper and lower surfaces of the strip and are
constituted by a bottom roll 20 having a slightly convex shape and
an upper roll 22 having a slightly concave shape to begin the
deformation of the strip to the desired shape. These rolls are
provided to have their axis of rotation extend transversely to the
direction of movement of the strip and are rotatable in the
direction shown by the arrows on the ends thereof. As noted above,
these rolls engaging the upper and lower surfaces of the strip in
addition to partially forming it to the desired shape also act to
drive or advance the strip through the machine.
A second set of transverse rolls comprising a lower convex roll 24
and an upper concave roll 26 may be provided. These rolls would
have radii of curvature greater than those of the rolls 20 and 22
in order to further form the strip to the desired arcuate shape.
Further forming rolls may be provided by a pair of opposed vertical
rolls 28 and 30 driven about axes perpendicular to the axis of
rotation of the rolls 20, 22, 24 and 26. These rolls are provided
with concave surfaces engaging the lateral edges of the strip 2
forcing it further toward the desired arcuate shape. A similar set
of vertical rolls 32 and 34 are provided to engage the lateral
edges of the strip in the same manner. These rolls are mounted in
the machine with their axis of rotation closer together than the
axis of rotation of the rolls 28 and 30 in order to further form
the strip 2 to the desired arcuate shape. By using various
combinations of forming rolls of which the arrangement in FIG. 4 is
intended only as representative of one combination that may be used
the strip may be gradually formed from its flat configuration as
shown in the right-hand portion of FIG. 3 to the arcuate
configuration as shown in the left-hand portion of that figure. In
addition to rolls actually forming or partially forming the strip,
the forming stage 16 may also include stock guides 35 consisting of
guide rollers engaging the edge and top and bottom of the strip
adjacent the edges on both sides thereof and movable inwardly and
outwardly as indicated by the arrows. When provided with such stock
guides, the roll may by adjustment inwardly or outwardly
accommodate strip material of different widths without the
necessity to change the forming rolls.
Referring again to FIG. 5, it will be seen that the strip 2 has
been formed into an arcuate shape having a radius of curvature R.
By forming the strip in the manner shown the amount of zinc which
will adhere to the surface will be that necessary to obtain a
coating that will be strongly bonded to the surface of the strip,
have a desired thickness, good coverage of the entire surface and
good appearance. These results will be achieved without the use of
excessive zinc for the excess will be provided with a path to be
easily wiped off down the downwardly sloping sides of the arcuate
strip back into the bath for reuse. Likewise, the concave
undersurface of the strip will be similarly coated with the excess
returning to the bath. The limitation on R are related to the
thickness of the strip, it being important not to exceed a minimum
value for a given thickness in order that the strip not be deformed
beyond a point where reforming into its flat form is no longer
possible. On the other hand, a maximum value of R is determined by
the need to a surface curved downwardly sufficient to permit the
excess zinc to run off.
After being formed to the arcuate shape, the strip is advanced to
elements linearly aligned therewith for washing and pickling the
surfaces of the strip in preparation for continuous galvanizing.
The washing and pickling of the machine may be similar to that
disclosed in the U.S. Pat. to Krengel et al. No. 3,122,114 and
comprise a first stage 36 for providing a strong wash of that
surface and a second stage 38 for providing a medium wash. As in
the disclosure in the patent to Krengel et al., these washes may
take the form of solutions of alkali in hot water. From the alkali
washes the strip is advanced to a rinse stage 40 where it is
sprayed with rinse water to remove the alkali from the surface.
After rinsing, the strip may be pickled at the stage 42 using a
solution of hydrochloric acid. After a water rinse by a stage 44
and a steam rinse by a stage 46, the strip is advanced to the
entrance to an inert gas housing 48.
In the interior of the housing 48 there is first provided means to
preheat the strip to a temperature in the range of 650.degree. to
950.degree. F. in order that the galvanizing operation may be
carried out more rapidly. The preheat means is illustrated as being
constituted by an induction heating device comprising an induction
heating coil 50 encompassing the strip and connected to a suitable
source of electrical energy (not shown). Also included within the
inert gas housing is a bath of molten zinc, a portion of which is
in a trough 52 disposed within the housing. This construction may
be the same as that disclosed in the Krengel et al. patent referred
to above, it being noted that suitable means shaped to conform to
the surfaces of the strip and engaging therewith may be provided at
the exit end of the trough to wipe off the excess zinc as the strip
leaves the housing 48.
In order to prevent flow and bead formation, it is desirable to
freeze the metal as soon after wiping as possible. For this purpose
use can be made of a water quench as in the form of a water spray
or flow coat 54 following substantially after the strip emerges
from the housing.
From the galvanizing section the galvanizing strip is advanced
sequentially through a series of water spray sections 54 to cool
down the galvanized strip if it has not otherwise been sufficiently
cooled in the freezing step.
If it is desired to produce flat strip, the machine will include a
series of reforming rolls 56. These reforming rolls may be arranged
as shown in FIG. 6. In this figure, there is shown a first pair of
transverse rolls 58 and 60 wherein the roll 58 is positioned
beneath the strip 2 while the roll 60 is positioned above it.
Engaging the surfaces of the strip the rolls have the effect of
forcing the arcuately shaped strip back toward its flat
configuration. Whatever number of rolls are necessary may be
provided and in this figure there is included an additional set of
rolls 62 and 64 which are arranged for rotation in the same
direction as the rolls 58 and 60 but which have their axis of
rotation closer together than the axis of rotation of the rolls 58
and 60.
After being reformed into flat strip, the strip 2 may either be cut
into desired lengths by a shear 66 or wound on a storage reel 68
depending on the needs and the desires of the user.
Rather than use the forming and reforming rolls just described the
strip may be passed through the galvanizing bath flat but with its
longitudinal axis tilted slightly from the horizontal. In this
manner, a sloping surface for excess run-off may be provided
without bending the strip. Roller guides may be provided in lieu of
the forming rolls 16 for this purpose.
An important concept of this invention resides in the method for
continuously galvanizing the strip material as a continuous
operation. For this purpose it is desirable to contact the cleaned
surface of the strip 2 with molten zinc for a sufficient time to
enable the desired reactions to take place to form the desired
thickness of galvanize on its surface, and it is important to carry
out the reactions under non-oxidizing conditions. Otherwise
undesirable oxides of the metal will form at the elevated
temperatures under which the reactions are carried out.
The desired reducing or non-oxidizing atmosphere can be maintained
by the enclosure of the galvanizing zone within a sealed housing
into which an inert or reducing gas can be introduced with a
maintenance of a non-oxidizing atmosphere. This can be accomplished
by a sealed enclosure but it is preferable to make use of an
enclosure which is capable of removal to gain access to the
interior of the galvanizing zone but without interferring with the
ability to achieve atmospheric control when in position of use.
The desired characteristics have been achieved in the construction
illustrated in FIG. 2 of the drawings by the use of a rectangular
hood 68 having a horizontally disposed top wall 70, side and end
walls 72 which extend perpendicularly downwardly from the edges of
the top wall into a trough 74 facing upwardly from a frame 76 which
extends all about the galvanizing zone. The bottom edges 78 of the
side walls are received within the trough for support of the hood.
The trough is at least partially filled with a material 80 such as
fine sand into which the lower edge of the side walls becomes
embedded to effect a sealing relationship all around which
militates against the flow of free gases all around for atmospheric
control. One or more inlets 82 for the inert or reducing gas are
provided in the walls of the hood for introduction of such inert or
reducing gas in the amounts to maintain a non-oxidizing atmosphere
therein.
Referring more particularly to FIGS. 2 and 3, the galvanizing means
comprises an elongated horizontally disposed housing 52 in the form
of a trough aligned axially with the line of travel of the sheet 2
for passage of the sheet horizontally through an intermediate
section of the trough from an inlet 84 at one end and 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 reservoir 92 of
molten zinc with means for displacement of the molten zinc from the
reservoir to the inlets at a rate sufficient to maintain the trough
substantially filled with molten zinc to cover the strip advancing
therethrough. The inlet 88 may be adjacent the inlet 84 through
which the strip is introduced for concurrent flow of the molten
zinc through the trough with the strip and in position to overlie
the strip so as to direct the stream or streams of molten zinc onto
the strip. Alternatively, the location of the inlet 88 and outlet
86 may be reversed to provide for counter flow of the molten zinc
with the moving strip.
The trough 52 is further provided with a drain opening 94 in the
bottom wall 96 thereof with a downpipe 98 leading from the drain to
the reservoir. The drain opening is of small dimension to enable a
thin stream of molten zinc constantly to flow therethrough but at a
rate that is considerably less than the rate of introduction of
molten zinc into the trough less the amount that escapes through
the openings so that there will be an overflow of molten zinc over
the sides of the trough forming the inlet to the trough, but
insuring an amount of molten zinc in the trough to cover the strip
passing therethrough. It is preferable to provide that the ends of
the trough be higher than the sides in order that the overflow
occur at the sides. In this manner, the entry of the strip below
the surface of the bath in the trough without its prepared surface
having previously been contacted by overflow zinc is insured.
A wiper means such as the element 100 may be provided in the outlet
86 to control the thickness of the zinc coating without bead
formation and to provide for removal of excess for return to the
reservoir while in a molten state and while still in a protective
atmosphere. A similar element may be provided in the inlet 84 to
engage the surface of the strip. These two elements may be
constituted by guide blocks shaped to conform to the surface of the
strip and may be constructed out of materials to which molten zinc
will not adhere. An alloy of tungsten and aluminum have been found
useful for this purpose.
Following the element 84 a conduit provided with outlets to supply
a sharp blast of heat encompasses the strip to remove excess zinc
and in this manner control the thickness of the zinc coating,
provide a luster finish and ensure a uniformity of the coating.
As may be seen from FIGS. 2 and 3, the strip 2 enters the bath of
molten zinc in the trough 52 below the level of its surface 102.
During its passage through the bath, it travels in the same
horizontal plane and exits similarly. This method of galvanizing
results in a number of advantages. The most important advantage is
that a complete high quality coating is obtained on all surfaces
including the edges of the strip. As pointed out above, that by so
doing it becomes possible to continuously galvanize strip steel
normally slit from wide coil stock in thickness greater than 0.036
inches and produce a product which exhibits a resistance to
corrosion including rust on all exposed surfaces including edges
and the sides of punched holes for periods longer than heretofore
possible. In addition, a shiny smooth finish is obtained free of
flaws such as wrinkles or spots where the galvanizing is
incomplete.
There seems to be a number of reasons why these results are
obtained. First, by entering the galvanizing bath below the level
of its top surface the strip material is constantly exposed to
fresh bath material inasmuch as it does not have to pass through
the dross that forms on the top of the baths such as found in the
prior art. Second, the fact that the bath is continuously
circulating provides the advantage of a good dispersion throughout
the bath of any alloying materials that may be used. Further,
because of the circulation optimum temperature distribution is
achieved enabling easier control of the temperature and a better
ability to maintain the bath at a desired temperature.
A further advantage is that it becomes easier to remove foreign
materials which tend to rise to the top of the bath and
contaminates which are heavier and fall to the bottom. Other
advantages which are obtained include an ability to control the
length of the trough 52. Heretofore, this has been done by the use
of additional guide rolls in the bath or by providing deeper baths.
Further, it becomes easier to put the continuous galvanizing line
in operation as there is no longer any need to thread the strip
over guide rolls in the bath.
As described above, the method and apparatus may be used to
continuously galvanize flat strip by the use of forming and
reforming rolls. However, it is also possible to galvanize formed
or partially formed strip material. Thus, in FIG. 7 an alternative
embodiment is illustrated wherein the strip 2 after leaving the
housing 48 and the quenching or cooling stage 54 may pass through a
series of forming rolls 102 to be formed to any desired shape such
as rectangular sections or angular constructions. After forming, a
shear 104 may be provided to cut the formed strip to desired
lengths.
FIG. 8 illustrates a formed strip which may be continuously
galvanized using the method and apparatus of this invention. This
is a more complex shape and comprises a strip having two curves 108
and 110 which may be used for guard rails of the type installed
along highways. In this case, the machine could include a punch at
a point prior to the surface preparation stages to form holes 112
in the trough 114 formed by the double curve of such a strip. This
punch could be provided prior to the forming stage so that the
holes are in the formed strip prior to galvanizing. This
arrangement permits excess zinc draining into the rough 114 from
the sloping sides of the curves to reenter the bath and yet at the
same time the sides of the holes 112 are galvanized so that
corrosion protection is thereby provided. Alternatively, prepunched
strip could be used when the shape which may be galvanized using
the method and apparatus of this invention is illustrated in FIGS.
9A and 9B.
FIG. 9B illustrates the desired end product, that is, a rectangular
section 116 in which all the exposed surfaces are galvanized. Such
a shape could be formed by first partially forming the strip
material into the angular shape 118 shown in FIG. 9A, and then
after surface preparation, passing this shape in the same manner as
described above through the galvanizing bath. After galvanizing and
cooling, additional forming rolls could complete fabrication of the
strip 118 into the rectangular configuration 116.
When it is desired to galvanize flat strip which is to be reeled
for further processing elsewhere, a loop such as that shown by the
reference numeral 10 in the upstream part of the machine may also
be used between the shear 66 and the wind up reel 68 in order to
permit continuous operation. The process of such a loop would
provide storage for galvanized strip while an empty reel is being
exchanged for a reel which has just been filled.
It will be understood that changes may be made in the details of
construction, arrangement and operation as well as in the materials
employed without departing from the spirit of the invention,
especially as defined in the following claims.
* * * * *