Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates Lo the formation of contoured
metal sections such as chann~els, studs, corrugated cladding
sheets, rlbbed decking sheets, highway guard or safety
rails and other structural or like elongated elements; from
flat strip, sheet or plate metal (hereinafter referred to
simply as "strip").
Such metal sections have longitudinally extending
shaping such as flutes, corrugations, ~lange, ribs and like
formations, which give the section a contoured "non-flat'
transverse cross-sectional shape which is known as the
profile of the section and prevails constantly throughout
the length of the section.
Contoured metal s ctions, when the strip is of
relatively light gauge, can be produced by roll forming.
Where the gauge of the metal is too great for roll forming
the articles can be formed directly from the strip, in a
heavy brake press, in a single blow of the press; but this
requires expensive dies and a large and expensive press;
moreover, the length of the articles has to be limi~ed to
~what the press can handleO
An alternative to the prior art ~ethods discussed
above is t~o form the contoured metal sections by what is
known as "Progressive Stamp Forming". An example o this
kind of metal shaping is provided by the invention subject
of our British Prior Patent 1,450,235.
Shortly stated, progressive stamp forming as
practiced in terms of the said British Patent, consists
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in forming, from a flat metal strip, a contoured section
having a constant profile which prevails throughout the
length of the section; the method comprising:
(a) intermittently advancing the strip longit-
udinally into and through the working ambit of a pair of
mutually reciprocating press tools so that each advancement
step is perpendicular to the direction of tool reciprocation
and is a fraction of the length of the tools measured in
the direction of advancement,
(b) performing each of the advancement steps
while the tools are mutually retracted,
(c~ causing the tools to bend the strip without
changing its thickness, during each halt of the strip
between successive advancements, and
~d) causing the bends to be such that that last
occurring brings the strip into contour conformity with the
required constant profile, and such that the bends other
than the last, impose on the strip a plurality of transitory
profiles each of which, successively in the direction of
strip advancement, is less in contour conformity with the
original. flatness o~ the strip and more in contour confor-
mity with the required constant profile.
The prior process of progressive stamp forming
referred to above has proved itself to be highly effective
and of considerable co~mercial importance; however, in
some respects it, and the apparatus for performing it, are
open to objection. ~or example, the use of forming dies
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or tools in which one/die moves rectilinearly and normally
rela~ive to the other, necessitates halting of the strip
during each working blow of the press. This, in turn,
requires the strip feed to be effected only while the dies
are mutually retracted. If the strip feed is performed
manually, not only does time loss occur, but as well the
feed steps are rarely regular or uniform. If, on the other
hand, the feed is performed mechanically the mechanism is
relatively complex, and power consumptiorl high because of
` the unavoidable high-frequency, repetitious positive and
negative accelerations.
Another and more general shortcoming of the prior
art, concerns the rectilineal reciprocation of the movable
die. Presses in which the movement of the movabl~ die is
rectilinear necessitate the use oE crank shafts connec~ing
rods and the like to convert rotary motion into rectilinear
motion and they require fly wheels to store up sufficient
energy for even running of the reciprocating masses. More
over, guides have to be provided to ensure that the platen
or plunger carrying the movable die is restrained against
motion in any direction other than the required rectilinear
direction. The restraining guides may be in the form of
cylindrical bars, vee runways and similar parts which
require extensive precise machining so that the guide bars
or the like will be truly parallel throughout their full
lengths, and this kind o~ accuracy makes the construction
of these presses a costly matter. Moreover, the number of
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relatively movable parts involved gives rise to large bear-
ing areas where clearances are required and these clear-
ances summate, with the result of undesirable overall
slackness of the press arising.
The object of the pres,ent invention is to overcome
the indicated disabilities in a very simple way by the
provision of press mechanism which is operable to perform
a method much the same as that described previously herein
(in that paragraph hereof containing parts lettered (a) to
(d3), except that by the present invention one of the two
press tools, in addition to having a component of rectilin-
ear motion relative to the other tool normal to the direc-
tion of strip advancement, is also operable with a component
of motion in the direction of strip travel; also, the other
tool is movable, at least in the direction of strip travel.
By this expedient the dies themselves become the driving
elements whereby the strip is fed through the pressing
station in the required longitudinal travel direction.
The invention provides~apparatus for forming, from
a flat metal strip, a contoured section having a constant
profile which prevails throughout the length of the section
and is progressively applied to the strip by advancing the
strip longitudinally into and through the working ambit of
complementary first and second forming dies; said apparatus
comprising:
(a) a machine frame;
(b) a pair of carriers which have said forming
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dies respectively mounted thereon;
(c) means for mounting one of said carriers on
said frame so that the die carried thereby is able to
move relative to said frame with a first component of
reciprocatory mo~ion normal to the second of said dies and
with a second component of reciprocatory motion in the
direction of strip advancement between said dies;
(d) means for mounting the second of said
carriers on said frame so that the die carried by it is
movable relative to said frame at least in the said
direction of strip advancement; and
~e) drive mechanism whereby at least said first
die is driven in exercise of its movability as aforesaid,
and so that at all times of operation said dies remain
spaced apart at least by a pre-selected minimum distance.
Examples of the invention are illustrated in the
drawings herewith.
Fig. 1 is a schematic side elevation of a preferred
embodiment of a press mechanism according hereto.
Fig. 2 is a plan projected from Fig. 1.
Fig. 3 virtually repeats a portion o~ Fig. 1 in
showing a modified arrangement.
Fig. 4 is a side elevation of press apparatus which
is substantially the same as that shown in Figs. 1 and 2,
but somewhat more detail~d in being representative of a
practical embodiment of the invention.
Fig. 5 is a plan projected from Fig. 4.
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Figs. 6 and 7 are sectional end views taken on
lines 6-6 and 7-7 respectively appearing in Figs. 5 and 4.
Referring to Figs. 1 and 2, a machine frame 8 has
upright standards 9 furnished with bearings for driving
shafts 10 and 11. Shafts 10 and 11 carry eccentrics 12
rotatable within "strap" bearings 13 provided in tool
carrier beam 14. Drive shaft lO is drive-connected through
suitable worm gearing or the like as indicated at 15 by a
motor or the like as indicated at 16; and shaEt 11 is co-
-driven so that the two eccentrics 12 are at all times
similarly angularly ph~sed; that is to say, so that the
maximum throw diameters o~ the eccentrics are at all times
-parallel.
In Fig. 2, a drive connection between shafts 10
and 11 is shown by sprocket means indicated at 17.
It will be seen that upon rotation of the eccentrics
12 the carrier 14 will execute an orbital motion as indicated
by arrows 18 so that the carrier has a component of
vertical movement equal to twice the throw of the eccentrics
and a component of horizontal motion (also equal to twice
the throw of the eccentrics) in the direction of strip
advancement as indicated by arrow 19.
A second tool carrier 20 is movable in the direction
of strip ad~ancement and, in the embodiment under discussion,
in slave relationship repeats the horizontal component of
motion of the top carrier 14 by reason of carrier 20 being
provided with bearing holes 21 in offset lugs 22 on the
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carrier 20. These holes 21 slidably receive striker fingers
23 which are fixedly mounted at 24 on the carrier 14.
Carrier 20 may be mounted on the machine frame 8 by way of
support rollers as indicated at 25 or it may be furnished
with longitudinal runner ribs reciprocal in groove runways
or the like on the base 8.
Appropriate complementary progressive stamp forming
tools are fixedly mounted on the carriers 14 and 20 for co-
operative inter-action in the forming of strip material.
It will be appreciated that the complementary tools and the
manner in which they are mounted will be such that notwith-
standing their movements they remain parallel and that the
distance of their closest mutual approach will be equal to
the thickness of the metal strip under progressive stamp
formation. With orbital motion as indicated at 18 the
direction of strip advancement will be as indicated by arrow
19 and during relatively close approach of the complementary
tools they will, while imposing the required transitory ~-
profiles on the through-going strip, also act frictionally
to grip the strip and advance it step-by-step through the
working ambit of the tools.
I~ will be apprecia~ed that the bottom die carrier,
according to the present invention, is essentially capable
of movement in the direction of strip advancemen~ (as
indicated in relation to carrier 20 as shown in Fig. 1)
between the dies. It will also be appreciated that the
range of this movement of the bottom die (such as 20) is
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preferably equal to the component of motion in the direction
of s~rip travel of ~he die moun~ed on carrier 14.
With some die formations it may not be necessary for
the bottom die to execute the same range of horizontal
movement as the top die, and such an arrangement is
illustrated in Fig. 3 where the bottom die carrier 20A is.
mounted in exactly the same way as shown in Fig. 1 in
respect of carrier 20; but in this instance the carrier 20A,
instead of being compelled to operate in slave relationship
`to the top carrier 14A, is merely free to do so under
frictional influence when the strip being formed is fric-
tionally in touch with both of the dies. By this frictional
touchJ carrier 20A will be able to move in the direction
(19A) of strip advancement, and during those periods when
there is no substantial frictional contact of the through-
going strip with both of the dies, the carrier 20A may be
reverted to its previous location by any suitable means such
as the tension spring indicated at 26 having its ends res-
pectively anchored to the carrier 20A and also to a bracket
27 fixedly mounted on tne machine frame 8A.
The remaining figures of the drawings (Figs. 4 to 7)
illustrate a progressive stamp forming apparatus which in
principle of operation, is the same as that diagrammatically
shown in Figs.l and 2.
Referring to Figs. 4 to 7, a machine frame 28 has
upright standards 29 furnished with bearings for parallel
driving shafts 30 and 31. These two shafts carry eccentrics
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32 ro~atable within strap bearings 33 provided in tool
carrier beam 34. The shafts 30 and 31 are driven by motor
36 through suitable transmission devices indicated by
reduction worm gears 37, counter shaft 38 and belt drive
39.
A second tool carrier 40 is movable in the direction
of strip advancement and is in slave relationship to the
orbitally movable carrier 34 by reason of striker fingers
41 fixedly mounted on carrier 34 and vertically slidable
in bearings indicated at 42. The carrier 40 is mounted on
the machine frame 28 by way of conventional bearing elements
indicated at 43.
By way of example, Fig. 6 shows the carriers 34 and
40 with a complementary pair of progressive stamp forming
tools 44 and 45 mounted thereon and having between them a
flat strip 46 which is to be progressively formed thereby
into a corrugated roadside safe~y rail.
It will be understood that if desired, apparatus
according hereto, instead of having one of its die carriers
movable mere.ly in the direction of strip advancement, may
have both of its tool carriers mounted on eccentrics so
that both are orbitally movable concertedly; that is to say,
that each is mounted on two eccentrics and is so driven
that all four eccentrics are operable so that at all times
the top and bottom dies remain parallel, and so that at
the point of closest mutual approach (a distance equal to
the thickness of the strip to be formed) they both are
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moving in the direction of strip advancement.
The foregoing is a description of a preEerred embodiment
of the invention which is given here by way of example only.
The invention is not to be t:aken as limited to any of the
specific features as described, but comprehends all such
variations thereof as come within the scope oE the appended
claims.
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