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Патент USA US3075078

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Jan. 22, 1963
K. H. BALL
3,075,068
SHEET METAL SHRINKER
Filed July 22, 1958
2 Sheets-Sheet l
Jan. 22, 1963
>
K. H. BALL.
3,075,063
SHEET METAL SHRINKER
Filed Jilly 22, 1958
2 Sheets-Sheet 2
?ing b; ij'lg- 4
' ,477'0244/
ttes
2
3,tt’l5,tl68
Kenneth H. Bail, Los Angeles, tl'aiii, assignor to Douglas
Aircraft Company, Inc, hanta Monica, Galif.
SHEET METAL SHRINKER
Filed Italy 22, 1958, Ser. No. 750,140
12 Ctnims. (El. are-149)
urge metal away from its center toward. its periphery,
thereby to neutralize the outwardly directed stresses in
the oil can that originally caused its distortion. The oil
can area is thus freed of residual stresses and remains
permanently in coplanarity with the remainder of the
sheet, and will not “locally ?ex.”
It is preferred, especially in the case of “hard” alloy
sheets, such as those of titanium, to apply “balanced”
This invention relates to sheet metal and is particularly
heat concurrently to both faces of the oil-can and to
concerned with sheets that, as received from the rolling
these and other ends, both the ram and the platen in
mill, incorporate snap-buckles within the area of the
corporate heating means, such as electric resistance heat
sheet. These snap-buckles are localized areas of residual
ers embedded therein.
stress left by unbalanced thermal or unbalanced mechani
Although the invention contemplates that other forms
cal stresses in forming the sheets in the rolling mill and
of apparatus are equally suitable for carrying out the
their stress-?eld is that of radial compression directed 15 present method, the aforementioned form is, by way of
toward the center of the buckle. In the sheet-metal
example, shown in the accompanying drawings and will
working art these snap-buckles are universally designated
be described hereinafter in conjunction therewith.
as “oil-cans,” as distinguished from the precise metal
In these drawings, FIGURE 1 is a perspective view of
lurgical term, “snap-buckles.” Accordingly, hereinafter
said apparatus in the initial, “pre-pressure,” or clamping
they will be referred to as “oil-cans.”
20 stage before the ?nal-pressure lever has been swung for
The latter consist of localized, ?exible areas which,
Wardly;
like the bottoms of oil-cans, are so unstable that they
FIGURE 2 is a detailed perspective view, partly in sec
can be “snapped” back and forth out of the plane of the
tion, of the mechanism for applying the ?nal, or shrink
remainder of the sheet. These areas detract seriously
ing, pressure to the oil-can and releasing same;
‘from the usability of such sheets for fabricating sheet
FIGURE 3 is a- vertical, substantially central section
metal articles and are believed to be caused primarily
of the ram-head group, the platen group and the die
by rolling mill thermal or mechanical faults that leave
group, taken on line 3—3 of FIGURE 1, with the ram
residual stresses in certain locations on the sheet. These
stresses usually take the form of radially outwardly
directed forces acting outwardly from the central portion
of the area, placing this area under a “pre-stress” that
is not in stable equilibrium.
Subject invention provides methods and means for re
moving these residual stresses by a metal-shrinking action
in an apparatus of an improved nature. It is applicable
to all types of metals but ?nds its greatest utility in shrink
in the initial-pressure position;
FIGURE 4 is a similar view of the same parts in the
final~pressure, or sheet-shrinking, position thereof;
FIGURE 5 is a vertical, substantially central View of a
second species of the shrinking dies, with the curvatures
of same and of the oil-can greatly exaggerated, and
d. FIGURE 6 is a similar View of a third species of the
res.
In order to cary out the present method, the machine
ing aluminum alloy and titanium alloy sheets.
Brie?y, this novel shrinking involves the primary step
depicted in the drawings comprises a frame 12 generally
of peripherally clamping the oil can area with mating
mounting a platform 14. In the outer, upper end of
the C-frame there is formed a hollow, upright guide,
hearing, or supporting, collar 15 for slidably receiving a
novel ram~unit i7 coaxially mounted therein for move
pressure-rings arranged respectively in clamping contact
with the upper and the lower faces of the sheet; heating
the rings and the concerned area of the sheet to a'pre
determined temperature dependent upon the composition
of C~conformation and having an upright arm 13 sur
ment upwardly and downwardly.
of the sheet; and thereafter applying to the heated oil
In the conventional manner, the ram-unit includes a
can area, a compression force of such magnitude, direc
tion and duration as to remove or neutralize the afore
cylindrical shaft 16 having mounted thereon a rack 21
said residual stresses.
One type of apparatus contemplated by the invention
for performing the method of the present concepts essen
tially consists of a machine generally of the arbor-press
thereto on a shaft 25} extending horizontally through
type but modi?ed, among other respects, to convert the
‘ plunger member of the press into a two-phase ram co
operative wtih a complementary platen, the ram and
platen being adapted to engage the oil-can area with an
initial, “pre-pressure” clamping action that prevents the
metal outside the clamp, and not oil-canned, from being
affected by the subsequent shrinking operations. The
ram and platen each carries a shrinking die in the center
thereof, the dies being complementary. These dies are
arranged in pairs that are complementarily shaped to
suit the particular shape and area of oil-can to be dealt
adapted for operation by a pinion 23 carried adjacent
member 15.
At one end, shaft 20 bears a hand-wheel
22 operable to apply the initial clamping pressure, or pre
pressure, to the oil can area. At its opposite end-portion
shaft 20 bears a group 19 of elements arranged and
adapted to force the dies to apply the ?nal pressure to
the, preferably, heated oil can. In much the customary
manner, this group 19 includes an adjustable length
lever 24 rotatably mounted on shaft 20, the lower end of
lever 24 bearing a counterweight 25 for facilitating clock~
wise viewing it from the left hand side of FIG. 2 move
ment of lever 24, as viewed from the left in FIGURE 1,
upon exerting the ?nal, or shrinking, pressure upon the
clamped oil can area. A ratchet gear member 27 is ?xed
to shaft 2% adjacent lever 24. The sleeve 26, provided for
enabling adjustment of the effective length of lever 24,
with, as well as its “hardness.” In the second phase of
operation of the ram, which is in two vertically spaced
carries a spring-loaded pawl 29 for engaging it with mem
halves united by a- cornpresison spring, with the periphery
ber 27. A pawl-controlling pin 30 protrudes lateraliy
of the ram clamping the periphery of the oil can to the
from a slot 32 in the pawl-bearing sleeve 26 and seats
periphery of the platen to prevent affecting the metal ly
ing outside the ram-platen unit, a shrinking force is
applied to urge the ram and platen still more tightly
together. The upper die being axially mo-vably mount
ed in the lower “half” of the ram, this action causes
the complementary dies to apply to the clamped oil-can
a combined compressive and shrinking force sut?cient to
and unseats with respect to a cam groove 34 in a collar
33 which is rotatively carried by member 15 and sur
rounding shaft Zft for use in enlarging or diminishing
the maximum arc of travel of lever 24 from its position
of rest. When collar 33 is moved back into the plane
of the paper, as it were, in FIGURE 2, the beginning
point of the arc is spaced back far, providing a greater
amaoes
3
arc of 'travel; and vice'versa. When the pin leaves the
groove 34, the pawl is urged forwardly, or clockwise in
FIGURE 2, against the ratchet, thus rotating the shaft
20 clockwise and urging the ram forcefully downwardly
on its ?nal. pressure stroke.
2
Considering the ram ‘unit in detail, it ‘comprises, ,as
shown in‘FIGURES 3, and 4, two vertically spaced cylin
4
- peripheral margin of the die-combination are adapted to
act in such manner as to urge the heated metal thereat
radially outwardly and away from the center of the die
combination, thereby to neutralize the stresses that origi
nally set up the oil can. Since this type of hard'alloy
sheet, 70, 70A, can withstand considerable direct com
pression without “ringing,” this 'die-set is well adapted
for shrinking such sheets. Further, the “Transite” base
‘spring 38, the two portions 35 and. 37.beingjcoaxially
62 being resilient to an extent, will yield and prevent deep
slidable on a central cylindric member 43 mounted co 10 “ringing” of softer alloys. The concavity of the upper die
axially in bores 42 centrally traversing members '35 and
enhances the desirability of this species in that the entire
37. vTwo sets of vertically‘ separated insulating discs, as
upper surface of the oil-can is continuously in contact with
of micarta, 39 and 40, are provided in member'35, chie?y
this concave surfacefrorn the inception of the shrinking
, dric portions 35 and 37 cooperatively engaged by a coiled
‘ for the purpose of preventing the transmission of heat to
the hand wheel 22 via the'intermediate metallic structure.
The cylindric member 43‘ is substantially hollow, hear
ing two parallel laterally spaced, vertical bores, as shown,
in each of which is mounted an electric resistance heater
41, which may well be of the well-known ‘fchromalox”
type, to each of which electric leads 46. are connected,
thermocouple ‘51 and leads 51A being also provided, as
shown. ‘A cylindric socket 45 is provided in the, upper
end of member 35 for enabling union of the ram unit
i with the rack-bearing press rod or ‘shaft 16. The lower
operation, enabling the greater amount of heat-transfer
necessary in dealing with the :harder alloys. Obviously,
also, a larger \area oil cancan be dealt with [than in FIG
URES 1-4, inclusive.
Where the, sheetis composedof an alloy that is of
nearly extreme hardness, a set of dies, 72 and 49, as shown
in FIGURE 6, is employed. Both these dies tare planar
on their working faces so that the unit loadrexerted there
by on the sheetis lower than in thecaseof the other two
sets of dies raforedescribed.v Consequently, there is .a
_ reduction of. the danger of -“Brinelling” of the oil can
end-portion of member 43 incorporates radial- bores 47
for receiving removable stop pins 48 provided to prevent
while it is being shrunk. Incidentally, the two .planar
face dies. of FIGURE 6 may, if necessary, be employed,
separation of members 37 and 43 when in use. Die 50
after the sheet has been processed by means of the-dies of
includes a relief groove 52 for breaking'the' .“suction” 'ac
FIGURES. 1-5, inclusive, as “?nishing” dies. That is,
tion of the‘ die with its socket in order to facilitate the
any slight “ringingJF-or other imperfections in the sur
removalof the die. _
i
30 face of the sheet remaining after the aforesaid processing
The lower‘ end-portionyof member v43‘b‘ears a central
may be smoothedout by means of the dies of. FIGURE 6.
, bore in which compressive shrinking die 50*ismounted.
The upper die, 50, in‘ this species has a convex working
face, as shown, in order to enable it and die 57 tovapply
‘ to the rather small oil can shown in the sheet of rather
soft alloy, a high unit loadsut?cient to reduce the up
wardly humped oil can to coplanarity with the remainder
of the sheet.
’
The ?nal pressure exerted by means of the lever 24
may be varied to apply different magnitudes of pressure
according to the thickness of the sheet and its hardness.
To this end, it is only necessaryto vary the angular posi
tion of ‘the collar 33 on the shaft 20, thereby to corre
spondingly vary the arc oftravel of the lever 24 in apply
ing this ?nal pressure.
The platen 53 has a socket in its upper portion that is
'It will be apparent to those skilled in the art that various
coaxial with the aforesaid central bore. »In the socket 40 changes and. modi?cations may bemade inthe construc
is seated the shanked die 57. having a planar working
tion set forth withoutdeparting from thespirit of the in
. face, as shown, adapted to cooperate with the convex
vention, ‘and it is intended that all such changes and modi
faced die in order to shrink the oil-can.
?cations shall be embraced within the scope of the sub
Platen 53 contains an electric resistance heating coil‘54 . joined claims.
including leads 55 and 55A. The lower face of the cylin
I claim:
~
dric platen bears a relief cut-outf59 for accommodating 45 ‘ 1. A methodof- eliminatingan oil-can in metallic sheet
thermal stresses, and a suction-breaking vent 60 centrally _ material, comprising: supporting said sheet in‘ an opera
traverses the platen group from base 62 to the die socket
tions zone in an attitude in which both faces’of the oil
. 57, thereby "to facilitate the removal of'the, die 49. "A
can are rectangularly accessible_;lclamping' the peripheral
' layer of insulating material, 63,- such as Micarta, .or the
marginal portion of theoil-can in a substantially immobile
like, is interposed’ between the bottomv ‘of .the cylindric 50 condition, leaving the remainder .of the oil can relatively
platen and the platform 14.
It ‘will be comprehended that the ram group terminates,
', at its lower end, iri-an- annular face 64 which in effect
mobile;.heating the oil-can while the marginal periphery
thereof is clamped; and balancedly applying to-the area
of the oil-can that lies radially, inwardly of the aforesaid
' constitutes a clamping ring and that the cylindric platen
clamped, portion a compression force directed rectan
member terminates, at its upper end, in a complementary 55 gularly to the faces of the sheet and of such magnitude
‘clamping ring 65. The two rings, on. application of the
‘as to produce aneifective resultant vector directed radial
“pre-pressu-re,” seize the peripheral portion of? the oil
' 'can tightly and stably enough to, in effect, ‘segregate the
ly outwardly and downwardly with respect to the radially
inwardly acting residual forces causing the oil can.
oil can from the remainder of the sheet, so that, upon ap
.- 2. A method of eradicating an “oil-can” in a sheet of
plication of the dies, metal cannot be “pulled” from or 60 metallic material, comprising: supporting the’sheet in an
.“pushed’? to the regions of the sheet that lie outside the
attitude in which both facesof the oil-can are approach
- rings.v For, such woulditself be likely to setup new
able towardsJt-he faces; applying an oil-can segregating
residual stresses in the aforesaid regions.
clamping action to the peripheral marginal portion of the
Because of the convexity of the working face of the die
oil-can so as to in effect segregate the metal of the oil
50, its pressure is concentrated in the central region there 65 can from the remainder of the sheet; heating the oil-can
1 of, thus causing it to apply a high unit load to the sheet.
while the peripheral marginthereof is clamped; and ap
plying substantially rectangularly to the faces of the oil
_ Such is desirable or permissiblefor heated ‘isoft” alloy
sheets.
7
In FIGURE 5,-theinventi-orr comprehends a set’ of dies,
can within the periphery thereof a compressive action
> urging the metal in the free portion of the oil'can radial
- 71 and ‘49, so shaped and con?gured as to deal with the 70 ly outwardly from the center towardv the periphery of
shrinking of the harder alloys,isuch as aluminum 75 ST
the oil-can ‘and neutralizing permanently the ‘radially di
rected residual forces that caused the oil-can.
alloy and titanium alloys. Die 71 has, as shown, a con
3. A method of eliminating an oil-can from a sheet
cave working face adapted to‘provide (1). smaller ‘unit
loading ;_and (2) a,veftically-,relatively~ large ‘space be
.-of metallicv material, comprising: supporting said .sheet
tween the dies into which the forces generated at the 75 in an operationsi'zone in an attitude in which both faces
5
8,075,068
of the oil can are accessible from a direction extending
6
interposed coaxially between the two segments and en6
substantially rectangularly to said faces; clamping the
abling upward resilient yielding of said second segment
peripheral marginal portion of the oil-can in a substan
upon application to said ram means of the second-phase
tially immobile condition so as to leave the remainder of
actuating force.
the oil can relatively free; heating the oil-can while the
8. An apparatus according to claim 6 and in which said
pair of dies consists of a convex-‘faced die mounted co
peripheral margin thereof is clamped; and applying rec
tangularly to the opposite faces of the free portion of
said oil-can compressive forces directed to urge the metal
axially in the lower end-portion of said ram means and
a plane-faced ‘die mounted coaxially in said supporting
in the free portion outwardly toward the periphery there
means with the plane-face confronting the convex face,
of, thereby to neutralize the radially directed residual 10 whereby to enable said apparatus to shrink out of said
sheet, oil cans therein that protrude upwardly from said
stresses in said oil can.
4. In a machine for eliminating oil-cans from the harder
sheet.
alloy metallic sheet-material: the ‘combination with means
9. An apparatus according to claim 6 and in which said
for supporting the sheet in an attitude in which the faces
pair of dies consists of a ?rst concave-faced die mounted
of the oil-can are accessible in a direction perpendicularly 15 coaxially in the lower end portion of said ram means and
a second plane-faced die mounted coaxially in said sup
to the faces; of ?rst and second coaxial, and opposedly
separated clamping members movable relatively to each
other to clamp the peripheral portion of said oil-can sub
porting means, the ram means and the supporting means
being arranged coaxially with the plane-face of said sec
ond die confronting the concave ‘face of said ?rst die,
stantially immobile in said attitude; heating means car
ried by at least one of said movable members for apply 20 whereby to enable said apparatus to shrink out of said
sheet oil cans therein.
ing a predetermined heating to said oil-can while same is
10. Apparatus for eliminating an oil-can in a metallic
clamped as aforesaid; ?rst and second metal shrinking
sheet of material, comprising: means for supporting said
dies respectively mounted within the con?nes of the ?rst
sheet in a press-like apparatus with the sheet in an attitude
and second clamping members; the ?rst die being movable
inside the ?rst clamping member and having a warped 25 in which both faces of the oil-can are accessible to forces
directed normal thereto; means for clamping the periph
metal-working surface, the second die having a substan
eral marginal portion of the oil-can in a substantially im
tially planar surface confronting said warped surface and
mobilized condition leaving the oil-can free of said clamp
serving as an anvil whereby movement of the ?rst die
urges the metal of the oil-can radially outwardly away
ing means; movable die means and ?xed die means ar
from the center thereof in a direction opposed to the direc 30 ranged coaxially inside said clamping means, said die
means being predeterminedly mutually shaped with respect
tion of the residual stresses in the oil-can, thereby to
to each other and to the oil-can for forceful contact of the
shrink and eliminate the oil-can.
dies with the oil-can to compressively urge metal away
5. Apparatus for eliminating oil-cans from metallic
from the center and to the periphery of the oil-can; and
sheet-material, comprising: means for supporting metallic
means for moving the movable one of said dies to ?atten
sheet-material with the oil-can in an accessible attitude;
means movable rectangularly toward the supported oil
the oil-can into permanent coplanarity with the remainder
can, said movable means and said supporting means in
of the sheet.
11. Apparatus for eliminating an oil-can from a metallic
sheet of material, comprising: means for supporting said
cluding opposed, complementary portions for applying a
clamping action to said oil can substantially peripherally
thereof upon further movement of said movable means;
means for heating the clamped oil-can to a predetermined
temperature; ?rst and second dies mounted coaxially in
sheet in a press-like apparatus with the sheet in an attitude
in which both faces of the oil-can are accessible to forces
directed normal thereto; means for applying to the periph
ery of the oil-can an oil-can segregating clamping action
and sheet immobilizing action; means for heating the oil
mobile, said dies having mutually confronting surfaces 45 can in the area inside the clamped periphery thereof; and
compression exerting means for shrinkingly urging the
shaped with reference to each other and to the shape of
metal in the oil-can that lies in the area inside the clamped
the oil-can that movement of the ?rst die toward the
periphery radially outwardly from the central region of
second die bodily urges the metal of the oil-can radially
the oil-can toward its periphery thereof, the so urged
outwardly toward the periphery of the oil-can; and means
for moving the ?rst die toward the second die until the 50 metal neutralizing the radially inwardly directed residual
stresses in the sheet that gave rise to the oil-can.
oil-can is ?attened against the second die thereby to shrink
12. Means for eliminating the oil-can from a metallic
and eliminate said oil-can.
sheet, comprising: means for supporting said sheet in an
6. Apparatus for eliminating oil-cans from metallic
attitude that exposes both faces of the oil-can to forces
sheet-material, comprising: a frame; means in the frame
for supporting the sheet with the oil-can accessible rec 55 directed normal thereto; means for clamping the periphery
of the oil-can in a stationary condition; means for heating
tangularly thereto; two-phase ram means movable coax
only that portion of the oil-can that lies within its clamped
ially toward said supported oil can to clamp same periph
periphery; and ?xed and movable die means for applying,
erally with the supporting means in a ?rst phase of move
spaced alignment in the apparatus, the ?rst die being ver
tically movable and the second die being ?xed and im
in a direction normal to the faces of the oil-can, compres
ment of the ram means; and a pair of mutually coaxial
metal-working die means disposed in said ram means and 60 sive forces having components urging the metal in the
central region of the oil-can radially outwardly toward
in said supporting means and mutually shaped and ar
the periphery thereof so as to shrink and eliminate the oil
ranged to apply a metal-shrinking action the oil can in
the second phase of said ram so as to neutralize the radi
ally directed forces in said oil-can.
7. Apparatus according to claim 6 and in which said 65
ram means consists of a columnar element movable ver
can.
References Cited in the ?le of this patent
UNITED STATES PATENTS
tically upwardly and downwardly in said frame with
438,408
Dewey ______________ __ Oct. 14, 1890
reference to said supporting means, said columnar ele
ment having a lower portion vertically divided into two
1,809,168
Junkers _________ __, ____ __ June 9, 1931
11,960,000
2,010,996
Chesney _____________ __ May 22, 1934
Junkers ______________ __ Aug. 13, 1935
2,112,653
2,350,884
MacLennan __________ __ Mar. 29, 1938
Ernst ________________ __ June 6, 1944
coaxial segments mutually spaced apart, the upper seg 70
ment being ?xed to the lower end of the columnar ele
ment and the lower segment terminating at its lower end .
in an annular clamping face; means disposed coaxially of
2,439,571
Julian _______________ _.. Apr. 13, 1948
said segments on which the lower segment is movable
with respect to the upper segment; and resilient means 75
2,693,638
2,783,363
Anderson ____________ .._ Nov. 9, 1954
Gunther ______________ __ Feb. 26, 1957
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