Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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BA~KGROUND OF THE IN~ENTION
The invention relates to a method and apparatus useful
for the preparation of multiple gauge metal strlp by an
operation comprising a draw-shaving operation and a
drawing operation employing hydrodynamic lubrication.
In many applications, such as the production of copper
alloy strip for the formation of electrical connectors and
c the like, it is necessary to provide a multiple gauge
thickness in the metal strip. Heretofore, such conventional
' 10 procedures as continuous milling have been employed to
produce the desired variations in gauge. Such processes
suffer from the disadvantages of being time-consuming and
generating an unfavorable form of scrap.
Another procedure which has been investigated in the -
, art comprlses the reduction to gauge by a rolling operatlon. ;~
Rolling operations in production are unfavorably restricted
to certain shapes, tend to involve complex and costly
tooling and are not good enough to provide products meeting -
, commercial tolerances and that are free from structural ~
defects. -
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Another approach to metal reduction which has been
investigated is the combination of shaving followed by
drawing as disclosed in U.S. Patent No. 3,055,102 to Shaw -
et al. In Shaw et al., a workpiece is reduced uniformly
along its entire surface area by a method which employs a
tool combining a 360 cutting head mounted ahead of a .
drawing or extrusion die, between which is provided a
channel for the introduction of a lubricating fluid into
contact with the workpiece. Shaw et al. suggest that the
fluid is employed to minimize or eliminate chatter or
wandering of the workpiece during the combined operation,
and in that connection, is preferably maintained under
pressure while in contact with the workpiece.
Though Shaw et al. deal with a combined process,
certain deficiencies exist in its application to multiple
gauge ~etal strip. Specifically, the application of ~-
shaving force against only a portion of the total surface
of the workpiece would magnify the problems which Shaw
et al. sought to remedy in such a manner and at such a
degree that the solution proposed in the patent would
prove inadequate. The chatter and uneven surface would
not be effectlvely prevented by the employment of the
- pressurized fluid in contact with the workpiece exiting
the shaving tool cutting edge.
With respect to the application of drawing to the
preparation of multiple gauge metal strip, certain
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complicatlons resul~ from the tendency of conventional
metal flow. That is, in the normal drawing process,
reduction of the thickness in a section results in an increa~e
in section length, so that if the thickness of a given
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shape varies across its width, the drawing process will
result in variable changes in length causing non-uniform
metal flow and stresses leading to buckling, twisting,
tearing and fracture of the workpiece. Though a wide variety
of drawing techniques are known, including the employment
of the hydrodynamic principal, none have been suggested
or would appear to alleviate the aforenoted deficiencies
associated with the drawing of complex multiple gauge
configurations. Referring specifically to Shaw et al., the
drawing die illustrated therein would be uncapable of
controlling the above-noted tendencies while simultaneously
attempting to prevent the occurrence of wandering and
chatter resulting from the shaving process.
Thus, the individual difficulties recognized with -
respect to shaving and drawing techniques as applied to
multiple gauge strip would appear to be magnified rather
than reduced by the application of the method and
apparatus of Shaw et al. Moreover, the individual known -
techniques of shaving and hydrodynamic drawing would
appear to offer little if any alleviation of the aforenoted
problems and would not suggest ~he method and apparatus
employed herein.
SUMMARY OF THE INVENTION ~-~
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In accordance with the present invention, it has been
found that multiple gauge metal strip may be prepared by
a process which comprises shaving said strip by
drawing said strip while under back tension through a
shaving apparatus whereby surface reduction of the strip
is confined to an area comprising from about 5 to about 50%
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of tota' surface area, and volume removal of strip
; material ranges from about 10 to about 60% as measured
in relation to initial strip cross sectional area, and
drawing the strip through a die defining said rectangular
cross section wherein direct surface-to-surface contact
between said strip and said die is prevented, the width
, dimension of said strip is unchanged and the ratio of
strip surface to strip cross sectional area change~ by
at least 30%.
The method of the present invention may be practiced
in varied sequence, whereby the incoming strip may be $
~i shaved to a predetermined gauge and then hydrodynamically
drawn to final dimension in either a single continuous
operation or in two or more distinct operations between
which various metal treatments such as interanneals
may be interposed. In a specific embodiment, the strip
is continuously shaved and then drawn in one operation
; occurring between a single pair of pay-out and take-up
capstans. In a further embodiment, the strip is drawn
to a given dimension and then further shaved to final shape.
~ The process of the present invention conLers the -
!~ advantage of reducing scrap generation during the forming
of the particular strip configuration, as the drawing
,` operation operates to prevent actual metal removal. Further,
the employment of the present method enables the strip
to acquire greater strength levels through work hardening.
In accordance with the present invention, apparatus
for the preparation of multiple gauge metal strip is
disclosed which comprises an ad~ustable shaving apparatus
comprising a shaving tool provided with horizontal and
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vertical ad~ustment means and further ad~ustable to
define a particular angle of incidence or rake angle
in relation to the incoming strip, and a drawin~ apparatus
comprising a hydrodynamic lubrication section containing
a quantity of suitable lubricant which is located ad~acent
a reduction section ending in a drawing die of appropriate
configuration, whereby the incoming strip picks up
; lubricant which is then placed in compression against
the surface thereof to effect the drawing of the strip
without surface contact with the drawing die.
Accordingly, it is a principal ob~ect of the present
invention to provide a method for the manufacture of
multiple gauge metal strip which enables the continuous
preparation o~ metal strip of exacting tolerance.
It is a further ob~ect of the present invention to
provide a method as aforesaid which resuits in the
reduced generation of metal scrap and confers improved
mechanical properties on the strip product.
It is a further ob~ect of the present invention to
provide a method as a40resaid which may be operated
in one pass.
Further ob~ects and advantages will become apparent
to those skilled in the art from a consideration of
the ensuing description which proceeds with relation to
the following drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 ls a perspective vie~ of a shaving apparatus
emplo~Jed in accordance with the present invention.
Figure 2 is a side view of the shaving apFaratus shown
, 30 ln Figure 1.
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Figure 3 is a cross sectional schematic view of the
drawing apparatus employed in accordance with the lnvention.
Figures 4, 5 and 6 are schematic cross sectional views
of multiple gauge strip configurations prepared in
accordance with the invention.
DETAILED DESCRI-PTION `~
In accordance with the present invention multiple
gauge metal strip of generally rectangular cross section
possessing regions of two or more var~able levels of depth
is prepared by a method comprising drawing the strip while
under back tension through a shavlng apparatus whereby an
appropriately configured shaving tool engages the surface
of said strip so as to continually inscribe a particular
pattern therein. The shaved strip may then either be
given an intermediate anneallng treatment or the like, or ;
may be directly introduced into a drawing die whereby the
strip ls sub~ected to hydrodynamic lubricatlon and drawlng
ls achieved without surface-to-surface contact between
the lncoming strip and the drawing die. - -
The shavlng method of this invention may be conducted - -
to achieve surface reduction of the strip within an area
comprising from about 5 to about 50% of total surface area,
and preferably from about 10 to about 40~ of sald area, and
strip volume removal of from about 10 to about 60%, and
preferably from about 15 to about 50%, as measured in
~, relatlon to the measured change in strip cross sectional
r, area.
" The above ratlo of the percentage of the total surface
area of the strip operated on by the shaving tool to the
' 30 volume of material removed thereby corresponds to the
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ratio of perimeter of the strip to the cross sectional area
of the strip before and after the shaving step, as the
surface area equals perimeter multiplied by length and
the volume equals cross sectional area multiplied by length.
The drawing operation noted above employs hydrodynamic
lubricatlon which facilltates one pass cross sectional
reductions ranging from 39 to 55% thickness wherein the
width dimension of the strip is unchanged and the ratio of
strip surface, which is measured by the perimeter of the
strip, to strip cross sectional area changes by at least
30%, and preferably ~rom 30 to 50%. ;
It may be noted that in both steps, there is relatively
little change in the strip surface area as measured by the
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perimeter, and that the ma~or dimensional change is with
respect to height or thickness values whereby the strip -
cross sectional area is signlficantly altered. -
As noted earlier, the method of the present invention
may be practiced in a variety of sequences to achieve
products of complex cross sectional configuration. Thus,
the primary sequence employed comprises the initial
inscription of the multiple gauge pattern by the shaving
operation, followed by the hydrodynamic drawing of the
formed shape to reflne and strengthen the patterned strip.
This primary sequence has been found to confer the greatest
economy and quality of production, as the shaving operation
:*; efficiently removes the bulk of the unwanted material from
the incoming strip, and the drawing operation achieves the
desired reflnement of tolerance and strengthening of the
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product through work hardening. This sequence can be
modified in the instance where the product possesses a -
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variety of complex indentations by the provision of a
shaving step following the drawing operation as will be
illustrated later on.
The shavlng operation employed in accordance with the
present invention is disclosed in our U.S. Patent 3,992,977,
issued November 23, 1976, the disclosure of which is
incorporated herein by reference. A shaving method is
disclosed therein which comprises drawing the strip while
under back tension through a shaving apparatus whereby
a shaving tool defining a cutting edge, possessing the
desired multiple gauge configuration, engages the surface
of the strip and continuously inscribes the desired
pattern thereon.
The shaving apparatus employed in accordance with the
present invention comprises an ad~ustable shaving tool
provided wlth a cuttlng edge defining a pattern corresponding
to the multiple gauge surface desired in the final strip
product. The shaving tool is primarily ad~ustable in two
directions to enable shaving to be conducted to successfully
achieve maximum possible strlp reductions measured primarily
in terms of volume removal. Maximum volume removal per
shaving pass may be generally determined in relation to the
yield strength of the strip and then coordinated with the ~ -
` cross sectional configuration of the desired end product.
This being done, the apparatus is then appropriately
ad~usted to achieve the extent of volume removal desired.
Referring to Figure 1, a shaving apparatus useful in
accordance with the present invention is illustrated in
perspective. Apparatus 10 comprises a bar-shaped shaving
tool 11, which is positioned in the figure with cutting
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edge tool 12 located ad~acent and on top of respective metal -
; strip M, As noted above, cutting edge 12 defines a cutting
pattern 13 whose configuration serves as the template for
the final configuration of ~he multiple gauge strip product.
As will be seen in greater detail in Figure 2, cutting edge
12 is disposed at a critical angle with respect to strip M
which facilitates the continuous operation of the method
of this invention.
Referring further to Figure 1, shaving tool 11 is
supported by adJustable tool holder 14 comprising tool
support structure 15 held within ad~ustable housing 16.
Housing 16 is fastened to a flat supporting surface through
base ~ which is provided with a tunnel-like channel for
the passage therethrough of strip M. Housing 16 is
provided with a horizontal ad~ustment 18 and a vertlcal
ad~ustment 19 comprising, respectively, calibrated screw- -
drlven slide connections. Ad~ustments 18 and 19 are Pine
ad~ustments provided in addition to a gross ad~ustment
which comprises slidable tool support structure 15 located
withln tracks 21. Thus, when the appropriate vertical
~, position is determined in gross, support structure 15 is
held statlonary and fixed in position by tightening screw-
threaded nut 22 against shaving tool 11, whereby the back
plate oP support structure 15, not shown, ls brought into
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flrm engagement with tracks 21. Thereafter, fine ad~ust-
ments of both vertical and horizontal position can be made -
with ad~ustments 18 and 19 noted earlier.
` As stated above, ad~ustments o~ depth of cut or
maximum stock removal are determined with respect to the
~ 30 yield strength of the strip and the particular configuration
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desired. In addition to the aforenoted ad~ustments of
vertical and horizontal position of the shaving tool, a
further critical ad~ustment is made which relates to the
rake angle of the tool edge. The rake angle may be defined
as the angle whlch the plane of the vertical leading
surface cutting tool or blade defines with respect to an
imaginary vertical plane perpendicular to the direction
of strip travel.
Referring to Figure 2, tool 11 is shown in greater
detail wherein an angle a is de~ined which is measured from
plane 20, shown in phantom which is perpendicular to the
direction of strip M, and the inclined surface 23 employed
at the lower portion of tool 11 closest to strip M. In
accordance with the present invention, it has been found
i` that a certain critical rake angle exists, which if exceeded,
~; results in a loss of control of the thickness of the
flnished strlp product. Often, a rake angle in excess of
6 the critical value causes the workpiece to ride up the tool,
with the result that excessive strip material is removed.
The rake angle found to be useful in the present method may
range from about 2.5 to about 25, and preferably from
about 5 to about 18. Accordingly, and as illustrated in
Figure 2, tool 11 is constructed such that the desired shape
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including the rake angle is machined into the tool tip or
cutting edge 12. The vertical leading face of the tool
~` lntegral with cutting edge 12 is thus inclined at an angle
lying within the range of rake angles noted above.
After the appropriate ad~ustments of shaving tool 11
have been made, shaving of strip M is accomplished by
pulling the strip across cutting edge 12 with the necessary
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force to overcome the shaving resistance at the tool. As
noted earlier, strip- M is supported and guided ln part by
the flat surface supporting tool holder 14. In addition, -
further supports or guides, not shown, could be employed in
lateral relation to the edges of strip M to prevent lateral
wandering from occurring during the shaving operation.
The shaving operation employed in accordance with the
present invention may be practiced as a single-pass or
multiple-pass operation. Thus, when the amount of stock
removal desired by the specific configuration sought exceeds
the maximum possible stock removal per pass, the desired
amount of stock removal may be divided among a plurality of
shaving passes which may be of equal amount of percentage
removal whereby the yield strength of the strip is not
exceeded and strip rupture is thereby prevented. Thus, the
strip may be sub~ected to a single shaving pass achieving
a desired percentage of reduction or may be sub~ected to
several such shaving passes, during which the material is
brought through the shaving apparatus, rewound on a take-up -
capstan and subsequently rerun through the apparatus for a -
further shaving pass. ~ -
After the shaving operation discussed above is --
completed, the strip may be ~ub~ected to a hydrodynamic
drawing operation. As noted earlier, the strip may be drawn
as part of the shaving operation, in which case the shaved
strlp exits the shaving tool and directly enters the
drawing apparatus. Alternately, the shaved strip may be
removed from the apparatus and given an intermediate
treatment such as an interanneal to achieve a given temper
before drawing is conducted. The drawing operation of the
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present invention, as disclosed in our U.S. Patent 4,015,459,
issued April 5, 1977, features the employment of hydrody-
namic lubricatlon, ln which the essential feature comprises
the provislon of a lubricant film of sufficient thickness
to prevent contact between the deforming metal and the
forming die.
The method of this invention ls illustrated in Figure 3
which schematically depicts a multiple gauge metal strip 30
passing through the drawing apparatus 31 of this invention.
As noted above, strip 30 has already received a primary -
multiple gauge configuration by the shaving operation set ;
forth above and, therefore, does not undergo a ma~or change
fi
in shape during drawing through apparatus 31. The strip
first passes through a container 32 which houses a quantity
of lubricant 33 sufficient to completely cover the strip.
Passage through container 32 is afforded by openings 34 and
` 35, respectively, which are in linear alignment with the
entrance ~ to the hydrodynamic section 37. The strip then
enters hydrodynamic section 37 bearing on its surface
lubricant 33 picked up during its passage through
container 32.
Hydrodynamic section 37 comprises an ad~ustable inlet
nozzle defining a cross sectional area of a size sufficient
to enable the passage of lubricant-coated strip 30. As
strip 30 passes through hydrodynamic section 37, the
lubricant picked up by the moving workpiece is compressed
and exerts a substantial pressure on the strip. The
lubricant prcssure which develops in the reduction section
38 must be sufficient to cause the deslred shape change
dictated by the die configuration without permitting
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surface-to-surface contact between the dle and the strip. ~;~
The determination of the lubricant pressure is governed by
several factors, such as lubricant viscosity, lnlet nozzle
length, drawing speed, clearance between the strlp and
nozzle and flow rate of lubricant through the reduction
section These factors can be varied to produce the
required pressure to provide the desired cross sectional
reduction of the strip and will be discussed ln greater
detail hereinafter.
The moving strip under lubricant pressure passes from
hydrodynamlc sectlon 37 to reduction section 38, where it
is drawn into the final product. Reduction section 38
comprlses a drawing die which defines a multiple gauge
configuration. As stated above, drawing is accomplished
wlthout surface-to-surface contact between the die and
strip 30, as well as no change in the width of strip 30
issulng from reduction section 38.
The essence of hydrodynamic lubrication in the present
drawlng operatlon is the provision of sufficient lubricant
pressure to achieve drawing without surface-to-surface
contact between the strip and the die. One of the
contributlng factors ls lubricant viscosity. It has been
found that lubricants o~ higher viscosity overcome certain
di~ficultles in the employment of the hydrodynamic
prlnciple, among them lubricant leakage and sufflcient
pressure build up. The employment of a lubricant material
such as a drawing soap further affects the- fabrlcatlon of
the die, as sealing abilities of the components are less
critical, ana the dimension, specifically those of the -
length of the inlet nozzle and the clearance between the
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strip and the nozzle. Accordingly, nozzle length may be
decreased and the clearance 39 as depicted in Figure 3,
which represents the distance between the wall of the nozzle
and the surface of the strip, may be increased, with the
further advantage that the tolerance requirements for the ~- -
incoming strip may be relaxed.
Other factors influencing lubrlcant pressure comprise
drawing speed and flow rate of lubricant through the
reduction section, both of which are positively correlated
therewith. Thus, lncreased drawing speed results in
increased lubricant flow rate, both of which increase the ;;
pressure exerted on the incoming strip.
As noted earlier, another feature of the method of
this invention resides in the design of the reduction
section. Certaln dimensional criteria were determined to -
be important in order to ensure straight exiting of the
strlp without buckling. These criteria are as follows:
` 1. The same volume of material must exit the die as
enters the die.
` 20 2. There must be equal percentage reductions in
height over the entire cross section of the strip and
reductions must occur uni~ormly in any transverse plane
section through the deformation zone. That is, if a
transverse section were to be observed at any point along
the deformation zone, the percentage reduction across the
entire section of the strip, including all variant gauge
sections, should be equal. In accordance with thls
requirement, the surface~ of the die which define the
Yariation in gauge must be dlsposed at slightly different
angles with respect to each other, as well as to the
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longitudinal direction of the strip workpiece. This
particular aspect of the invention will be illustrated by
the description of the drawing die in Example I, below.
3. There is to be no change in the width dimension of
the strip workpiece as a result of the drawing operation.
As noted before, this requirement dictates that the reduc-
tion occasioned by the present invention is not uniformly
taken across the entire surface o~ the workpiece, with the
result-.that .the:surface to.cross s.ectional area ratio varies
by at .least-.30%, and partlcularly ~etween 30 and 50%. This
variation distinguishes the preparation of products in
.. accordance with the present invention from multiple gauge
processes and products known in the art. Further, the .;~
malntenance of substantially the same surface component .
throughout the drawing operation comprises one of the . .
.; unexpected aspects of the lnventlon, as the frictional
component of the process, normally linearly related to the
surface component, is not proportlonately diminished as with
- conventlonal drawing processes wherein all dimensions of the
workplece are simultaneously proportionately reduced.
Partlcularly, the signlficant reductlons in strip cross
:~ sectional area render the successful practlce of the
present method even more surprislng, as the signiflcantly
reduced strip is less capabie of coping with the
` consistently high level of friction exerted through the
.,
vlrtually unchanged surface area.
.. Referring again to Figure ~ the apparatus useful for :
hydrodynamlc drawing in accordance with this invention is
schematically depicted in gross. Thus, contalner 32
housing a quantity of lubricant 33 is shown in linear
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alignment with hydrodynamic section 37 such that strip 30
may pass through openings 34 and 35 and into the inlet
nozzle comprising hydrodynamic section 37. Though hydro- -
dynamic section 37 is illustrated as detachably connected
to reduction section 38, it is contemplated within the
scope of this invention that both sections may be combined
in a unitary structure. The connection between hydro-
dynamic section 37 and reduction section 38 is rendered
leak-proof by seal member 40 whlch may comprise a 0.005"
thick flat copper sheet gasket. Both hydrodynamic section
37 and reduction section 38 are comprised of a primary
shape-defining element and a secondary shape-defining
element. In hydrodynamic section 37 primary nozzle element
41 comprises the base of the nozzle and secondary nozzle
element 42 comprises the top which is fastened thereto. ~ -
Likewise, reduction section 38 is comprised of primary die
element 43 which serves as the base of the die, and
secondary die element 44 attached thereto.
In practice, the use of hydrodynamic drawing entails
the provision of a starter or leader portion of the strip
to be drawn in a thickness corresponding to that defined by
the drawing die. Thus, in one embodiment, the strip is
placed with a leading edge protruding from the drawing die,
and pressure is then brought upon secondary die element 44
whereby strip 30 is compressed to the thickness illustrated
in Figure 3. After this compression is achieved, drawing
of the remainder of the strip material may commence and
will be carried out without further interpretation.
In order to gain a fuller understanding of the method
of this invention and to illustrate the underlying
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principles thereof, the following examples are presented
which were conducted to prepare multiple gauge products -
resembling, respectively, the configurations set forth in
Flgures 4, 5 and 6.
EXA~PL~ I -
Rectangular strip prepared from CDA Alloy 260 was
treated in accordance with the present invention by a
process which initially involved a shaving operation
conducted with a shaving tool as illustrated in Figure l
together wlth a strip guide and coiler and recoiler reels
to pay-off and wind-up the strip. The pay-off reel was
controlled to exert a back tension on the strip entering the
shaving apparatus. The initial strip material possessed
the cross sectional measurements of 1" in width and 0.080"
ln thickness. The strip was shaved in one pass to produce
a cross sectional shape resembling that illustrated in
Figure 4 which consisted of a flat strip o.o80" thick with
four l/16" rectangular grooves 0.030" deep in which about
12% of the surface area has been removed. The total volume
removed by the shaving pass was about 9~. -
The as-shaved strip was then hydrodynamically drawn
to approximately a 30~ reduction in strip cross sectional
area. Drawing was initiated by the placement of compressive
force of a gradually increasing nature to a maximum of
approxlmately 30 tons placed upon the leading edge of the :
strip which had been inserted into the reduction section
of the drawing apparatus. Upon compression of the strip
to the dimensions of the drawing die orifice, drawing was
commenced, which employed a graduated drawing die defining
a die angle for the ma~or thickness dimension of the strip
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of 10 and a die angle for the indentation or minor
thickness of the strip of 2,52. A one pass reduction of
30% was achieved with the result that the final dimensions
of the strip were reduced to a maximum thickness cf 0.056"
and a mlnlmum thickness, measured from the grooves of
0.035". The product exhiblted a smooth matte surface and
was generally uniform and linear.
EXAMPLE II
A further sample of CDA Alloy 260 was selected for
preparatlon of the multiple gauge configuration shown in
Figure 5. Shaving was conducted at a speed of 85 feet per
minute on a strip possessing the initial dimensions of
1.201 x o.og8". The shaving tool was disposed at a rake
angle of 12 and a shaving tension of 5,535 lbs. was
employed. The depth of cut achieved was 0.028" and the
volume removal comprised 18%. The final dimenslons of the
shaved strip comprised a ma~or thickness of 0.098", a minor
thlckness of 0.071" and a width of 1.2".
The above strip was then drawn to a 29% reduction at a
drawing speed of from 7 to 85 feet per minute. The draw
force exerted on the strip ranged from 2,475 to 2,700 lbs.,
and the film thickness of the lubricant employed ranged
from 0.0005 to 0.0015", and was thickest at the intermediate
speeds. The dimensions of the finally drawn strip comprised
; a ma~or thickness of 0.070", a minor thickness of 0.053"
and a width of 1.1995". The drawn product likewise possessed
an acceptable surface appearance and dimensional uniformity.
; EXAM~LE III
The present example illustrates an instance of the use
of draw shaving subsequent to a hydrodynamic drawing
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operation. Strip material prepared from CDA Alloy llO was
provided in a width of 1~643tr and a thickness of 0.115".
The strip material was in spring temper. The initial -
configuration comprlsing a center channel of a depth of
0.041t' and a width of 0.540" was inscribed by shaving. The
area removed by the shaving operation comprised 18% of the
strip volume. As the maximum area removed was determined
to be 17% in one pass, two passes were employed.
The shaved strip was then annealed at 375C for one
hour and was subsequently cleaned in a reducing atmosphere -
to remove accumulated surface oxide. The strip was then
hydrodynamically drawn to achieve a 5% reduction and to
provide the desired temper for further processing. The
strip possessed the final dimension comprising a ma~or
thickness of 0.109" and a final channel depth of 0.039".
After drawing, the'strip was further processed by shaving
to confer the final cross sectional configuration as shown
ln Figure 6. Four V-shaped grooves were placed in the
channel area of the strip which possessed depths measuring
10% of the thickness of the channel by a shaving operation
which was conducted in one pass. The four grooves were
provlded by shaving as the tooling necessary for the
provision of the grooves by hydrodynamic drawing was
prohibitive in cost and effort. The resulting strip product
possessed improved strength and tolerance conformity over
similar product produced by conventional processing.
'~ From the above, it can be seen that the present
method is adaptable to a wide variation in sequence to
, account for specific multiple gauge configuration.
Likewise, the respective operations may be conducted in
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either a continuous manner, or sequentially whereby
intermediate metal treatment steps may be conducted.
. Though particular apparatus has been disclosed and
suggested herein, it is to be understood that the present
lnvention may be practiced on apparatus of variations in
deslgn which is suitable for the achievement of the
ob~ecti~es disclosed herein.
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