Note: Descriptions are shown in the official language in which they were submitted.
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MET~IOD OF REBUILDING A STRIP hlIL.L GUIDE
~ackground of the Invention
_echnical Field:
This invention relates to strip mill guides of the
type normally employed to guide -the edges O:e strip between
the stands of a rolling mill and a me~hod o-f rebuilding them.
Description of the Prior Ar-t:
Prior s-tructu:res of this -type are -those s~e~ in my U.S.
Patents 3,289,457, 3,289,292, and 3,583,876 in which built
up strip mill guides and the me-thod of making the same are
disclosed. The inventions se-t forth in -these paten-ts and
particularly in Patent 3,589,876, have been widely commercial.ly
adopted by the steel industry and such bui].t up strip mill
guides have been reworked according -to Patent 3,589,876. Such
rebuilt guides have heretofore been largely limited to those
in which the edges of the steel strip being guided have
formed relatively uniform longitudinally straight grooves
in the guides and wherein the width of the grooves thus -formed
may be filled with a suitable alloy integrally welded to -the
guide. ~any strip mill guides become incapable of being
rebuilt due to the tendency of the steel strip emerging from
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the reducing -rolls to buckle or ripple arld -thereby create an
irregular shaped groove in the guide and/or a series of laterally
spaced grooves, some of which are longitudinally s-traigh-t and
some of which are irregular and undulating longi-tudinally of
the guide.
The present inven-tion makes i-t possible -to rework such
unusually worn guides and rebuild -the same satisfactorily.
Strip mill guides rebuilt in accordance with the present
invention may be repeatedly reworked and rebuilt and found
-to be improved in their lifespan characteristics and wearing
ability.
Summary o-f the Inven-tion
A method of rebuilding a s-trip mill guide having unusual
wear imparted configurations longitudinally thereof reshapes
the wear conf igUI ations laterally and longitudinally and
enlarges the area thereof to the extent that it lS dif-ficult
to obtain a good fusion zone for the weld metal to be applied,
uses a weld rod of approximately doubl.e -the diar.~eter
of the weld wire or weld rods hereto-fore known in the art
and with a manual metal arc process weld with increased power
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sufficient -to melt not only -the oversized rod, bu-t also supply
sufficient heat to penetrate the larger irregular area to
be rebuilt.
The present invention not only improves the original me-tal
Oe the guide, particularly with respect to wear characteri.stics
and grain structure but permi-ts -the guide to be rebuil-t
periodically -to replace the worn away metal, and of equal
impor-tance, the increased area being rebuilt and -the increased
volume of the larger rod employed and the substantially
increased power used resul-ts in less tu-rbulence in the melted
metal being applied and the elimination o-f the porosity in
welds without a cover gas or weld rod coating. ~dditionally,
the present invention provides for a greatly improved deposit
rate of more than thirty pounds of metal per hour which con-
siderably reduces the time necessary to rebuild a worn strip
mill guide and thus substantially reduces the cost thereof.
Description of the Drawings
Figure 1 is a perspective view of a built up strip mill
guide formed in accordance with this invention;
Figure 2 is a perspec-tive view of a strip~mill guide
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showlrlg -the unusual wear-shaped grooves :Eormed -therein when
the steel strip being guided moves in other -than a straight
line;
Figure 3 is a p~rspective view of -the strip mill guide
o~ Figure 2 -following the mechanical reshaping o~ the wear
grooves therein;
Figure 4 is a perspective view oE the s-trip mill guide
oE Figure 3 during the rebuilding of the reshaped wear grooves
therein;
lo Figure 5 is a ver-tical section on line 5-5 oE Figure 2
in enlarged detail;
Figure 6 is a vertical section on ]ine 6-6 o-~ Figure
4 in enlarged detail; and
Figure 7 is a vertical section in enlarged detail o-f the
section of the guide illustrated in Figure 6 and aiter the
excess weld metal has been removed to -form a transversely
smooth guide sur-face.
Description o-f the Pre~erred Fmbodiment
By reEerring to -the drawings and Figure 1 in particular,
it will be seen that a strip mill guide has been disclosed
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which is oF conventional size and shape and iEI -the example
chosen For illustration -the guide is approximately -thirty
three inches long by -three and one hal:F inches ln width and
one inch in thickness. It has a T-head a.-t one end, the
guide body being ind.icated by the numeral 10 and the T-head
being indica-ted by -the numeral 11 t The T-head is :Eormed
with a projec-ting extension 12 of lesser heigh-t than the
remainder of the head 11 of the strip mill guide so -that
it will fit beneath a mounting member in a conven-tional
moun-ting means positioned alongside the pass line of a s-trip
mill, for example, and adjacent a stand oi reducing rolls
therein.
The opposite end of the strip mill guide 10 has
angular end portions 13 and 1~ which angle toward one
another and terminate with a rela-tively narrow end portion
15 which is posi-tioned immediately adjacent said reducing
rolls. As seen in Figure 1 of the drawings, the strip mill
guide is in condition for installation in the guide means
of a strip mill.
By referring to Figure 2 of the drawings, the same strip
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strip mill guide will be seen in perspective elevation
with a plurality oi longi-tudinally extending grooves 16
and 17 -therein and which grooves 16 and 17 extend ~rom -the
end portion 15 to the T-head portion 11 and -the projecting
extension 12 as hereinbe-~ore reEerred to. The grooves 16
and 17 are formed in the strip mill. guide body 10 by the
longi-tudinal edges oE steel s-trip traveling between the
stands oE rolls in a rolling mill. It will be observed that
the grooves 16 and 17 are irregular in longi-tudinal con~Eigura-
tion as a resul-t o.E bowing or rippling o-E the steel strip
emerging Erom a stand o-E rolls in the rolling mill and that
they ~orm unusually wide and deep grooves in the strip mill
guide, it being understand tha-t -there are a pair oE such
strip mill guides, one on either side o-f -the pass line o-E the
rolling mill and arranged to engage and guide the longi-tudinal
edges oE the steel strip traveling between the stands o-E rolls
in the rolling mill.
Those skilled in the ar-t will observe that the resultant
wear pat-tern comprising the irregularly shaped grooves 16
and 17 contrast greatly with the more normal wear pattern
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occuring in strip mill guides such as illus-t:rated for
example in my prior pa'cen-t 3,589,876 wherein the l.ongitudinal
groove 16 is longitudinally straight and of relatively narrow
wid-th and depth.
It has become customary in the art to rebuild the strip
mill guides as disclosed in my aforesaid U.S. Patent 3,589,876 by
electric arc welding wherein a welding rod held by an
electric arc torch is supplied su-fficien-t electric current
to melt the metal of the welding rod and heat the area of
the groove in the strip mill guide so tha-t a desirable
fusion of the weld metal with the me-tal of the s-trip mill
guide takes place. IIeretofore, the largest diameter welding
rod available for use in such welding operations has been three-
sixteenth inch with most of the welding rod used commercially
being of smaller diameter. In welding with a three-sixteeth
inch diameter welding rod, electric curren-t at be-tween 225
to 320 àmperesis necessary to melt the metal and heat a
relatively small fusion area of the article to which the
welding rod metal is applied. IIeretofore, the largest
available electrode holder has been ra-ted at a maximum
curren-t capaci-ty of 500 amperes. The prob:Lem of a-ttempting
to rebuild a strip mill guide having a badly worn multiple
groove or a single enlarged groove condi-tion as hereinbe-Eore
described ln connect,ion with Figure 2 of the drawings with
the prior state o:E the art equipment has been insurmountable.
The present invention provides a satisfactory solution
to this longstanding problem by forming a welding rod oE
a quarter inch diameter or larger and providing an electrode
holder capable of safely handling 800 amperes and supplying
the electrode holder and the large diameter welding rod
with su-Eficien-t electrical current from a pair o-f 600 arnpere
welding machines to realize at least 80% duty cycle (~per hour~.
In Figure 4 of the drawings, such an improved and
enlarged electrode holder is indicated by -the numeral 18
and -the welding rod having a diameter of at least a quarter
inch is indicated by the numeral 19 and the conductor 20
is of a size to safely and e-Eficiently handle the power
outpu-t of a pair of 600 ampere electric welding machines
which are necessary to develop sufficient power -Eor the
purpose.
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By referring -to Figure 3 oi the drawings, it will be
seen -tha-t the grooves 16 and 17 in the strip metal guide have
been machined so as to remove me-tal lying between the grooves
16 and 17 and on opposite sides of the grooves to more uniformly
shape the irregular and/or undulating configurations of the
grooves 16 and 17 and form a single widened elongated cavity in
the strip mill guide 10. Such reshaping of the grooves 16 and 17
is no-t always necessary, bu-t has been found desirable in many
instances in providing a more unform channel in which the sub-
stantially larger amount of weld metal is deposited as illus-trated
in Figure 4 of the drawings.
By referring again -to Figure 4 of the drawings, it will
be seen that the deposited metal is generally indicated by
the numeral 21 and that it completely fills the channel formed
by the grooves 16 and 17 in the preheated strip mill guide.
Prehea-ting to at-- least 800F. is preferred.
In Figure 6 of the drawings, which is a vertical section
on line 6-6 of Figure 4, the deposited metal 21 will be seen
in cross section as deposited in the channel formed by the
grooves 16 and 17 and in Figure 7 of the drawings, the metal
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above -the sur~ace of -the strip mill guide 10 has been
machined so that there is a uniformly fla-t smooth wearing
sur~ace on the rebuilt strip mill guide 10.
The rebuilding of unusually worn strip mill guides,
such as -this invention is directed toward, makes possible
the economic rebuilding of the strip mill guides and their
repeated rebuilding and reuse and results in a rebuilt strip
mill guide having improved wearing characteris-tics in -tha-t
the rebuilt area of the guide is subs-tantially wider -than
the rebuilt areas of strip mill guides as heretofore known
in the art as disclosed for e~ample in my a~oresaid Patent
3,589,876. A considerably improved rebuilt metal area results
because the increased volume of molten metal being deposited
is considerably less turb.ulent than when a small amount is
deposited and is therefore free of porosi.ty which improves
wear life and at the same time improves iusion with the
preheated metal of the strip mill guide.
Of equal importance is the additional benefi-t that while
the previous metal deposit rates of four to ~ive pounds per
hour for the stick process and ten to twelve pounds per hour
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-~or the MIG process are greatly exceeded with the present
invention by which, using a one-quar-ter inch dlame-ter welding rod
over thir-ty pou.nds per hour of metal can be sa-ti.sfactorily
deposited.
The importance of -the present inven-tion will be
recognized by the fact tha-t the excessively worn and
irregularly worn strip mill guides can be rebuilt by
rewelding and the -rebuilding performed a number of times
while maintaining the alloy of the guide in its desirable
non-brittle sta-te.
The typical strip mill guide referred to herein is
80% copper, 10% tin, and 10% lead and has a normal fine grain
s-tructure which forms a suitable supporting body for the
rebuilt area -formed therein by this invention. The alloy
of the welding rod 19 shown flowing into the grooves 16
and 17 is high in lead and tin and preferably includes a
small amount of nickel, an alloy consisting of 78% copper,
10% lead, 10% tin and 2% nickel is suitable. The lead may
be present in the alloy in percentages running from 10% to 12%.
The tin may be from 9% to ll~o of the alloy and the balance
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copper except ~or the nickel which can be present in percentage
~rom 1% to 2% and under some conclitions may be eliminated,
such as where the lead and tin conten-t are very high.
Those skilled in the art will observe that -the heat
necessary to weld the metal in the grooves 16 and 17 or
the channel resul-ting ~rom the machining of these grooves
as hereinbefore described is su-fficien-t to remove or relocate
the tin and lead of the s-trip mill guide 10 wherein dendri.-tic
grow-th oi -the grain s-tructure occurs and which resul-ts in
an unsatis~actory strip mill guide as i-t becomes brittle,
easy broken and subject of rapid wear. By utilizing the alloy
disclosed herein which is high in tin and lead and preIerably
has nickel as a stabilizer, the heretofore believed normal
migration of the tin and lead is prevented and no dendritic
grain structure growth occurs. The alloy of the strip mill
guide and -the alloy of -the welding rod as disclosed in this
invention are similar to those disclosed in my aforesaid
Patent 3,589,876, but the desirable charac-teristics obtained
by using the alloy of Patent 3,589,876 are greatly improved
by the substantially increased area in which the alloy of
the welding rod is deposited in increased volume as the
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migration O:e the lead of the tin constituents in a bronze
alloy strip mill guide to -the last heat a:f:Eec-ted zone is
preven-ted by -the increased area of the deposited metal in
the increased channel size resulting -rom the irregular
shaped grooves in the unusual wear pattern of the strip mill
guides being rebuil-t. In other worcls, the lead-and tin
constituents of -the bronze alloy of the strip mil:L guide body
10 tend -to move in-to the areas away -Erom the weld and -towards
the center of the guide leaving the areas adjacent the weld
relatively free of lead and tin and thus accel.erating ~he
dendritic grain structure which leads to the -failure of the
strip mill guide as it becomes brittle, easily broken
and is subjected to rapid wear. By substan-tially increasing
the amount O:e the alloy deposited in the grooves and/or
channels in the strip mill guide as required by their sub-
stantially greater area, satuation of the guide metal by
the migration of -the lead and the tin of the alloy i~hibit
the dendritic growth and thus maintain the strip mill guide
in desirable condition.
It will thus be.seen that the built up strip mill guide
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disclosed herein comprises a substan-tial improvement in the
art and makes possible the reuse o~ severely worn gu.ides
and those having unusual wear patterns and permits theix
continuous use through a series oi rebuilding opexations,
none o~ which adversely a~-~ect -the grain structure oi the
original guide body.
Although but one embodiment oi the presen-t inven-tion
has been illustrated and described, it will be apparent -to
those skilled in the art that various changes and modi~ications
may be made therein wi-thou-t departing -~rom the spirit oi -the
invention and having -thus described my inven-tion, what I
claim is:
