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Патент USA US2378482

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Jmé' 19, 1945».
H, M JAGER
v
’ 2,378,482
MEANS FOR FORMING SHEET METAL
Filed Nov. 5, 1942
14.
E»;
p2 .7 515.15‘,
INVENTOR.‘.
H. M. JAG ER;
.
‘
v A770 NE)’.
\
Patented June 19, 1945
_ _
_ 2,378,482
r
UNITED STATES, eA'rENT'oFFicE
MEANS FORFORMING SHEET METAL '
‘ Howard M. Jager, Oceanside, N. Y., assignor to
Republic Aviation Corporation, a corporation of '
Delaware
Application November 3, 1942, Serial No. 464,357 7 _
vs Claims.’ (c1.153-4s) \
ing a modi?cation of the clamping. instrumental
This invention relates to forming ?at sheets of
ities shown in Figure 1;;
~ a. a
'
metal-into various shapes by the employment of
Fig. 3 is a diagram showing the resistances set
machines involving a drawing or stretching action
up in and by the clamp to'the stretching‘ forces;
and'lhas more particular reference to ya machine
involving provisions for anchoring or holding the
work vsheet during said drawing or stretching op
oration.
and
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The general object ‘of the invention is- to pro
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Figure 4 is a fragmentary, bottom plan viewpf
the clamp of Figure 2, with certain parts in sec
tion.
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The forming machine shown in Figural is
' vide a practical machine. for draw-forming sheet
there applied to form a skinlof a leading edge
section of an airplane wing‘ and includes a sta~
tionary form block ll, carried on a platen l2 of
the like.
I
. ‘
~
a conventional hydraulicipress- and a saddle
A particular object is to providea sheet‘ met
shaped frame‘ l3- to which the metal sheet is
forming'machine, involving a stretching opera
tion, in which the work-holding means will apply 15 clamped and-which frame is acted upon. by the
ram (not shown)- of the hydraulic press.
‘
a holding-pressure vwhich will be entirely inde
The metal sheet 26‘ to beformed is bent be
pen'dent‘of‘ the stretching strain or load, so that
forehand to conform 'roughlywith the shape of
there will be no possibility of the sheet being torn
the block H and has its opposite longitudinal
by the machine.
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metal into aircraft components of curved shape
such as metallic wing leading-edge sections and
I A more speci?c object is to provide a sheet 20 edges bent twice ‘in a “break” so‘ as to form two
externally projecting U -channe1led retaining‘ bor
ders. Thus prepared,‘ the sheetZll is slid end
metal forming machine, involving a drawing ac
tion, wherein the holding, pressure, or grip, of the
holding means on thework sheet can be ac
wise over the block. ll, while each of said U
curately set to the desired amount before the
machine is operated and yet can be readily ad
justed for any desired load lying between the
elastic limit and the tensile strength of the work
borders is inserted :between two, longitudinal
sheet; but which will-nonetheless apply a diiier- _
dovetailed recess l5 in which works a longitudinal
ential pressure on the held parts of the sheet and
whereby the-stretching or drawing load applied -
wedge-shapedfgang nut 16, cooperating with a
series of screws It for gripping and anchoring the
U-shaped ends of the work sheet 20. One side
19 of the lower jaw H is slightly higher than
beams l4 and IT forming theupper' and lower
jaws of a'clamp.
will be progressively absorbed and met by pro
gressively increasing sheet-retaining forces.v
g.
,
v
1
the other to compensate for the thickness of the I
A further particular object is to provide a ma
chine involving‘ work-holding means of a type
which» will spread the holding grip over a much
larger area of the work sheet than the sulbsistent
workholding means; and in which all the acting
sheet 20.‘
’
'
When thus clamped in position over the form
I l, the work sheet 20 can be stretched by lowering
the ram of the press over the frame l3 until the
sheet is stretchedland deformed and‘ assumes per~
surface of the work holding'means, though of this '
manently the shape of the form.
improved nature, will be incapable of forming
weakening punctures or indentations or other de
1
In the upper jaw I4 is provided a longitudinal
During this
40 operation there is no risk of tearing the work
formations in the held partof they work sheet, and
will be perfectly smooth and obviate the employ
ment of any kind of gripping’ teeth or projec
sheet along the inner bendof the U-borders, even
in the accompanying drawings, but it is to be
ing between the elastic ‘limit and the tensile _
if the pressure exerted by the ram rises beyond
the ultimate tensile strength of this sheet, due to
the fact that the gripping pressure is indepenobt
tions.
"
"
Several embodiments of the inventive objects 45 ent of the stretching force and is adjusted by
tightening the screws I8 to the desired'value ly
and concepts are described hereinafter and shown
strength of the sheet, and ‘also due to the fact
that the gripping pressure is Spread, over a rela
50 tively large area of the sheet,~i. e., the wing of
the U-border is pressed between the‘wedge l6 and
In the drawing
'
Y
.
one slanting side of the recess l5 and the, bottom
Figure 1 is a fragmentary side elevation of a
of the U-border is pressed between. the two vjaws
sheet metal forming ma'chine'embodying a pre
I 4, l1, thus providing a “differential” -> clamping
_ ferred form of the invention;
understood that the invention is limited in its
embodiments only by the scope of the sub-joined
claims.
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' ‘Figure’ 2» is a partial transverse" section show‘
.55
action.‘
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2
2,378,482
After the sheet 20 is thus formed-here into a
leading edge skin section—the ram of the press
is raised and the screws l8 are loosened and the
section is removed endwise from the gripping
jaws l4, l1.
border; and a second frictional reaction created
directly between the ?xed law and the other mov
able jaws of the clamp.
Having thus disclosed the inventive concepts
and several forms of embodiment thereof, what
is claimed is:
1. A clamp, comprising: a ?xed jaw having a
CA
Figures 2 and 4 show a slightly modi?ed form
of the preferred embodiment of the clamp. In
this form, the ledge or thicker part, [9, is re~
placed by a shim l9’ corresponding to the thick
ness of the work sheet 20 and the standard screws
l8 are replaced by studs 33 provided with left and
right-hand threaded portions.
dovetail recess; a jaw mounted free to move ver—
tically in said recess; a second movable jaw op
posed to both said ?xed jaw and said ?rst movable
‘jaw, a stud rotatably mounted in said second
movable jaw and having left and right-hand
On the lower
threaded portion of each of said studs is screwed
threaded ends, one of said ends passing through
said first movable jaw; an adjustable nut on the
other threaded end of said stud; diametrically op
a cylindrical nut 34 carrying two diametrically
opposed trunnions 35 on which is swivelled the
forked end 36 of a handle in two parts 31 fastened
together by means of short bolts 38. The curved
part of the fork 36 forms an eccentric or cam 39
posed trunnions secured on said nut; and a cam
lever pivoted on said trunnions to move said mov
able jaws in opposite directions simultaneously
towards said ?xed jaw.~
allowing for a quick operation of the clamp after
2. A clamp, comprising: a ?xed jaw having a
it has been adjusted by turning the studs 33 with ascreW-driver.
'
dovetail recess; a jaw mounted free to move ver
I
tically in said recess; a second movable jaw op
posed to both said ?xed jaw and said first mov
able jaw, a stud rotatably mounted in said second
movable jaw and having left and right-hand
threaded ends, one of said ends passing through
said ?rst movable jaw; an adjustable nut on the
other threaded end of said stud; diametrically
The handles 31 may be locked in their active
position by means of latches 40, pivoted as at M
to a bracket 42 mounted on the side of the lower
jaw ll’. Each latch 4|! swings in a slot 43, formed
between the two parts of each handle 31, when
said handle meets a ramp 44 formed at the free
end of the latch. ,
Figure 3 shows diagrammatically the relative
magnitude of the four reaction forces Pl, P2, P3,
and P4, which oppose the stretching force P when
the clamp is closed and the machine operated.
opposed trunnions secured on said nut, a cam
lever pivoted on said trunnions to move said mov
able jaws in opposite directions simultaneously
towards said ?xed jaw; and latching means for
locking said cam-lever in its active position.
As angle a=l00° and angle 18:80", and as the
3. A clamp comprising: a base member de?n
pressure applied by the wedge H5 or [6' on the
upturned wing of the U-channel is substantially as ing a wedge-action recess therein; a member
greater than the pressure applied by the jaw I‘!
- mounted in said recess for movement; a second
or IT’ under the bottom of the U-channel, there
are these relations: (1): PI+P2+P3+P4>P; and
(2) : P|<P2<P3<P4.
movable member mounted opposed to both said
members; a fastening member having oppositely
acting ends mounted rotatably in said second
By thus having four distinct clamping forces,
and increasing their magnitude, and by spreading
engaged
these forces over a much larger area than in sub
a
movable member and having one of the ends
with
said
fulcrum-member
?rst
movable
mounted
on
member;
said
rotat
able member adjacently to said second mov
sistent clamps, stress concentration at the point
able member and having lateral projections; and
where the sheet leaves the clamp is avoided, there
by entirely obviating the tendency of the sheet 45 a cammed-member pivoted on said projections
and organized with the aforementioned struc
to tear at this point. This tendency of the sheet
ture to apply pressure and tension respectively
to tear is further effectively precluded by having
to said second movable member and said ?rst
all the active surfaces of the jaws of the clamps
movable member, whereby to move both said
perfectly smooth, as distinguished from the
clamps of any analogous art of the kind in which 50 movable members-simultaneously in opposite di
said surfaces are roughened or provided with
small teeth in order to increase their gripping
action.
It is to be understood that each of the opposite
longitudinal edges of the work sheet is formed
with angled borders, or compound bends—here
disclosed as twice bent—merely in order to facili
tate clamping of the work sheet and in the ulti
mate product, these bends need not appear.
It is to be noted that although the triple-jaw 60
rections.
4. A clamp, comprising: a base member de?n
ing a wedge-action recess therein; a member
mounted in said recess for movement; a second
movable member mounted opposed to both said
members; a fastening member having oppositely
acting ends mounted rotatably in said second
movable member and having one of the ends
engaged with said ?rst movable member;
a
fulcrum-member
mounted
on
said
rotat
the tightening means disclosed, applies a differen
.able member adjacently to said second mov
able member and having lateral projections;
tial pressure over different portions of the com
and
clamp of the present invention, when operated by
a
cammed-member
pivoted
on
said
projections and organized with the aforemen
pound bends of the angled borders of the work
sheet, it applies this pressure progressively, and 65 tioned structure in such manner as to adapt
same to move both said movable members si
over the entire, total surface of the pre-formed
multaneously in opposite directions, and means
borders, with this pressure increasing most toward
for retaining said cammed member in its func
the extreme edges of the work sheet. .Moreover,
tioning position.
the stretching load is taken up, progressively, and
5. In a sheet metal forming machine the com
in sequence, by four increasing, retaining-forces: 70
bination with a form block, of a pair of super
a ?rst, rounded bend between the main portion
posed beams disposed upon each side of said
of the work sheet and each of the angled borders;
form block and longitudinally coextensive there
the friction indirectly created between the ?xed
with, the upper of said beams being provided
jaw and one of the movable jaws of the clamp;
a second rounded bend forming the angle of each 75 with a longitudinal groove in its lower face hav
3
2,378,482
'7. A clamp comprising a'?xed jaw having a
in'g upwardly divergent sides, a longitudinally’
extending wedge member freely mounted in said
groove‘ and having its longitudinal'sides substan
tially parallel to the upwardly divergent sides
of the coacting groove, and means coacting with
, recess in its clamping face the sides of which
diverge at acute angles to the face of the jaw,
a ?rst movable jaw mounted for movement in
said recess, trapezoidal in cross section, and hav
ing sides converging toward the face of the ?xed
said wedge and the lower of said beams for mov
ingthe wedge member downwardly in its groove
jawand parallel to the divergent sides of the
and bringing the lower beam upwardly‘ to coact
recess, a second'movable jaw opposed and 'paral—
lel to the outer faces of both the ?xed jaw and
the ?rst movable jaw, and means coacting with
the movable jaws to move them simultaneously
in a direction normal to the clamping faces of
the ?xed jaw and the second movable jaw and
at an acute angle to the clamping face of the
with the lower surface of the upper beam, where
by adjacent portions of a work sheet may be
clamped simultaneously between one side of the
, groove'and said wedge member and between op
posed faces of said beams.
- 6.‘ In a sheet forming machine, the combinae
tion with a form block, of a pairof superposed 15
beams arranged upon each side of the said form
?rst movable jaw.
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8. Aclamp comprising two spaced, ?xed mem
bers having their adjoining faces divergent, said
block and longitudinally coextensive therewith,
members combining to form‘ a composite ?xed
the upper of said beams being provided with a
jaw the outer face of which lies atan acute angle
longitudinal groove in its lower face having up:
' wardly diverging sides, each side being at an ,20 to both of said divergent faces, a wedge, trape
zoidal in cross section, disposed for movement
acute angle to the face of said beam, a longi-'
between the divergent faces of the said members
tudinal wedge member freely mounted in said
and having its outer face parallel to the outer
' groove having its sides substantially paral
face of said composite‘ jaw and its side faces
lel to the sides of the coacting groove, and means
coacting with said wedge and the lower of said 25 respectively always parallel to adjacent divergent
beams to clamp-a portion of a work sheet be
tween said beams upon one side of the “longi
. faces of the ?xed members, a second and mov
able jaw disposed parallel to the outer faces of
said composite jaw and said wedge, and means
connecting said wedge to said movable jaw to
wedge downwardly in its groove to clamp an
adjacent portion of the same work sheet be-. 30 move them simultaneously in opposite directions.
tween adjoining and coacting sides, of the wedge
HOWARD M. JAGER.
and groove.
tudinal axis of said beams and to move, said
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