Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PROCESS FOR THE TWO-DIRECTIONAL BENDING OF SHEET METAL
The invention relates to a process and apparatus for two-
directional bending of metal sheet clamped between two
clamping cheeks and bent by a bending cheek. With the known
sheet metal bending machines which have hitherto been used to
perform such a process, the bending jaw is only usable in one
working direction, i.e., for example, during swivel movement
from the bottom upwards in the clockwise direction.
Consequently, for sheet metal bending in opposite directions,
i.e., when a first sheet metal section is to be bent, for
example, in the clockwise direction and subsequently a further
sheet metal section in the counter-clockwise direction, the
metal sheet has to be turned between the individual bending
operations. However, particularly when large metal sheets of
several meters length have to be turned so that their top side
becomes the bottom side, this is an inconvenient and time-
consuming operation which is often also impeded by automatic
handling devices provided on the sheet metal bending machine.
The object of the invention is to so improve a generic process
that turning of the metal sheet between two two-directional
bending operations can be avoided.
According to the invention, a process is provided for two
directional bending of sheet metal having a first side and an
opposed second side, by a bending press, said process
comprising the steps of
(a) clamping the sheet metal by a clamping force between a
lower cheek and an upper cheek, leaving a projecting
length of the sheet metal project beyond the upper and
lower cheeks;
(b) applying a bending face of a bending cheek to the first
side of the sheet metal at the projecting length and
bending said projecting length through a specified angle
by pivoting the bending cheek in a first direction of
rotation about a pivot axis to provide a bent length of
the sheet metal;
(c) displacing the bending cheek away from said bent length
of the sheet metal in a first displacement direction
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extending in radial direction to said pivotal axis and
being arranged in a coordinate system rotating with said
bending cheek;
(d) following the withdrawal of the bending cheek from the
bent length of the sheet metal, moving the bending cheek
further in said first direction of rotation until, after
a movement over 180° in total, said bending face of the
bending cheek faces the second side of the sheet metal;
(e) within a period of time displacing the bending cheek in
a second displacement direction transverse to said first
displacement direction, releasing the clamping force and
moving the sheet metal a predetermined distance in said
first displacement direction to expose a further
projecting length of the sheet metal, and reapplying the
clamping force, whereby at the end of said period of
time said bending face faces the second side of the
sheet metal at said further projecting length thereof;
and
(f) applying said bending face to the second side of the
sheet metal at said further projecting length, by
displacement of the bending cheek in said first
displacement direction and bending the further
projecting length of the sheet metal through a specified
angle by pivoting the bending cheek in a second
direction of rotation opposite to said first direction
of rotation.
In another aspect, the invention provides a swivel bending
machine comprising machine frame, lower jaw, upper jaw and
bending jaw for performing the process according to the
invention is characterized in that there is provided on each
of the two end faces of the bending j aw a f first swing arm
which can be swivelled about the swivel axis of the bending
jaw, in that there is movably mounted on the first swing arm
a second swing arm, and in that there is provided on the
second swing arm a guide means which permits an essentially
straightline movement of the bending jaw extending
perpendicular to the swivel axis, the bending arm itself
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extending essentially perpendicular to the direction of
movement of the second swing arm.
The following description of preferred embodiments serves in
conjunction with the appended drawings to explain the
invention in further detail. The drawings show:
Figures several subsequent steps in the two-directional
1 to 8 bending of a metal sheet and
Figure 9 a device for performing two-directional sheet metal
bending according to Figures 1 to 8.
Figure 1 to 8 each show schematically the main parts of a
swivel bending machine, namely a lower jaw 1, also referred
to as "lower cheek", an upper jaw 2, also referred to as
"upper cheek 2", and a bending jaw or bending cheek 3. The
bending jaw 3 is mounted for rotation on the machine frame
(not illustrated) and can be swivelled about a swivel axis S
extending perpendicular to the drawing plane in Figures 1 to
8.
A sheet metal 4 is clamped between lower jaw 1 and upper jaw
2 by lowering the upper jaw 2 in the direction of the arrow
A and protrudes with a sheet metal length 5 beyond the cheeks
1, 2. The bending cheek 3 engages with its upper or bending
surface the underside of the metal sheet length 5. This side
is also referred to hereinafter as the first side of the metal
sheet 4; it lies opposite the top or second side of the metal
sheet 4.
Figure 1 represents the initial state of the bending process.
In a first bending step, the bending jaw 3 - cf. Figure 2 -
is bent by pivoting the bending cheek upwards, in a first
direction of rotation B through 90° in the counter-clockwise
direction, whereby the sheet metal section 5 is likewise bent
upwards in the counter-clockwise direction. The bending jaw
3 - cf. Figure 3 - is now withdrawn in a first displacement
direction of adjustment (arrow C), also referred to as "a
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first displacement direction" perpendicular to its swivel axis
S from the bent sheet metal section 5 so that - cf . Figure 4 -
it can be swivelled further upwards (arrow D) in an unimpeded
manner around this bent sheet metal section 5 until after
swivelling through a total of approximately 180° it faces the
second or top side of the metal sheet 4. The swivelling of
the bending jaw 3 according to Figure 4 again takes place
about its swivel axis S. As is further evident from Figure
4 , the bending j aw 3 is now located above the upper j aw 2
clamping the metal sheet 4 so that upon perpendicular lowering
from this position, the bending jaw 3 would come into contact
with the upper jaw 2 and not the metal sheet 4. Proceeding
from the position according to Figure 4, the bending jaw 3 -
cf. Figure 5 - is then moved in a second displacement
direction of adjustment along the arrow E until it is outside
of the range of the upper j aw 2 and can be lowered onto a
protruding sheet metal section which projects between lower
jaw 1 and upper jaw 2.
The directions of adjustment of the bending jaw 3 in
accordance with the arrows C and E in Figures 3 and 5,
respectively, now seem to extend parallel to one another. In
actual fact, the arrow C always runs parallel to the small
side and the arrow E always parallel to the large side of the
rectangle schematically representing the bending jaw 3 in the
drawings. Hence the two directions of adjustment according
to the arrows C and E always stand perpendicular on one
another, and in the transition from Figure 3 to Figures 4 and
5, the arrow C has likewise swivelled through 90°, as
indicated in dashed lines in Figure 5.
In order to define the spatial position of the second
direction of adjustment in accordance with arrow E, one can
also say that this direction of adjustment (arrow E) extends
perpendicular to the plane containing the first direction of
adjustment (arrow C) and the swivel axis S. This plane
extends in Figure 5 perpendicular to the drawing plane and
parallel to the arrow C.
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When the bending jaw 3 has reached the position illustrated
in Figure 5, the upper jaw 2 is raised accordingly (arrow A1)
- cf . Figure 6 - and the metal sheet 4 is advanced to the
right so that there is again a protruding sheet metal section
5a adjacent to the sheet metal section 5 which has already
been bent. When the metal sheet 4 has been pushed forward
into the position according to Figure 6, the upper jaw 2 is
lowered again (arrow A) and the metal sheet 4 clamped between
lower jaw 1 and upper jaw 2. Thereupon - cf. Figure 7 - the
bending jaw 3 is placed against the top or second side of the
metal sheet by displacement in the direction of arrow C1. The
direction of adjustment corresponding to the arrow C1 is
parallel to the arrow C but runs in the opposite direction.
Finally, as shown in Figure 8, by swivelling the bending jaw
3 through 90° in the second direction of rotation shown by the
arrow F downwards or in the clockwise direction, the sheet
metal section 5a is bent in the opposite direction to the
sheet metal section 5. The metal sheet 4 thus bent in the
opposite direction at its rim can now be removed from the
swivel bending machine. By corresponding adjustment of the
bending jaw 3 along arrows E and F, the swivel bending machine
is brought back into its initial position according to Figure
1.
For the performance of the inventive sheet metal bending
process explained with reference to Figures 1 to 8, it is
essential that the bending jaw 3 engage the first side of the
metal sheet during the first bending operation and the second
side of the metal sheet during the second bending operation,
as is evident from Figures 1 and 7, respectively. To this
end, adjustment of the bending jaw 3 in the first direction
of adjustment (along arrow C; Figure 3) is necessary to enable
transfer of the bending jaw 3 away from the bent sheet metal
section 5 from the first to the second side of the metal
sheet. However, since the bending jaw 3 (cf. Figure 4)
3 5 thereby moves over the proj ecting part of the upper j aw 2 , the
bending jaw 3 has to be additionally adjusted (cf. Figure 5)
in the second direction of adjustment in the direction of
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arrow E so that it can again be position (cf. Figure 7) on a
sheet metal section 5a protruding between lower jaw and upper
jaw. These two reciprocating movements for adjustment of the
bending jaw 3 which stand perpendicular on one another in
accordance with arrows C, C1 and E are thus essential to the
inventive process and, in the end, ensure that two-directional
sheet metal bending is possible without turning the metal
sheet.
Figure 9 shows schematically a swivel bending machine 10 which
is structurally designed such that the bending process
explained with reference to Figures 1 to 8 can be performed
on it. Figure 9 shows in a front view only the right side of
such a swivel bending machine 10. The other side is of
corresponding mirror-inverted design.
The upper jaw 2 and the bending jaw 3 which are mounted on a
machine frame are illustrated in Figure 9. The bending jaw
3 which can be swivelled about the swivel axis S covers in
Figure 9 the lower jaw 1 which is likewise mounted on the
machine frame 11 and is visible in Figures 1 to 8. The upper
jaw 2 is movable up and down in the direction of the arrow G
which corresponds to the arrows A and A1 in Figures 1 and 6,
respectively, to clamp and release the metal sheet 4. To this
end, the upper jaw 2 is connected to a hydraulic cylinder 12
attached to the machine frame 11. The swivel movement of the
bending jaw 3 about the swivel axis S is indicated in Figure
9 by the arrows H which correspond to the arrows B, D, F in
Figures 2, 4 and 8, respectively.
The swivelling of the bending jaw 3 is carried out with the
aid of a motor 13 attached to the machine frame 11. The motor
13 engages a first swing arm or locker 14 mounted for swivel
movement about the swivel axis S and can swivel it back and
forth perpendicular to the drawing plane of Figure 9. A
second swing arm 16 is mounted on the first swing arm 14 for
rotation about an axis 15. The axis 15 lies below the swivel
axis S. A piston-cylinder-unit 18 is provided between a
protruding foot 17 of the second swing arm 16 and the bending
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jaw 3. Its cylinder 19 is rigidly connected to the bending
jaw 3 and its piston rod 21 to the foot 17. The cylinder 19
can be additionally guided in straight-line configuration
along arrows I on the second swing arm 16. In this way, the
piston-cylinder-unit 18 forms a guide means for the bending
j aw 3 such that upon actuation of the unit 18 , the bending j aw
3 can be displaced in a straight line relative to the second
swing arm 16, away from the swivel axis S or towards this
axis. This first adjusting movement of the bending jaw 3 is
illustrated by the arrows I which correspond to the arrows C,
C1 in Figures 3 and 7, respectively.
The second adjusting movement mentioned hereinabove which
takes place perpendicular to the plane containing the first
direction of adjustment I and the swivel axis S (drawing plane
of Figure 9) is implemented with the aid of the second swing
arm 16. When the second swing arm 16 is swivelled about the
axis 15 with the aid of a drive motor 22 indicated in dashed
lines in Figure 9, the bending jaw 3 or at least its working
surface engaging the metal sheet to be bent is adjusted
perpendicular to the drawing plane of Figure 9 in accordance
with arrow E in Figure 5.
It is possible for the straight-line guide means formed by the
piston-cylinder-unit 18 in the embodiment according to Figure
9 to also be designed in a different way, for example, by a
sliding guide means for the bending jaw 3, with a separate
drive device, for example, an electric motor with a gear
spindle, then being allocated to this jaw 3. The second swing
arm 16 could - instead of being adapted to swivel about the
axis 15 - also be slidably connected to the first swing arm
14 in a different way, for example, likewise by a straight
line guide means. In any case, the structural design of the
swivel bending machine 10 must ensure that the adjustment of
the bending jaw 3 in the first and second directions of
adjustment (arrows C and E) explained in detail hereinabove
is possible.
