Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
CA 02282201 1999-09-15
Apparatus for Formin4 Sheds for a Jacauard Machine
Field of the Invention
This invention relates to an apparatus for forming sheds for a jacquard
machine
by means of hooks, which are movably guided in a frame between a high position
and a low position, and a lifting means for the hooks which can each
selectively
be coupled with associated driver stops of the lifting means via a control
element
that is mounted in the frame and is adjustable transverse to the path of
movement
of the hooks by means of a control means.
Description of the Prior Art
For forming sheds in jacquard machines, the warp threads forming the shed are
moved between a high position and a low position by means of a hook suspension
gear which each engages in a pulley block connecting two hooks (EP 0,287,921
A1 ). Depending on their actuation, these hooks provided in pairs can be
coupled
with two lifting knives moving in opposite directions, in order to move the
respec-
tive warp thread from the one into the other shed position by means of the
hook
suspension gear. For adjusting the hook suspension gear it is also known (EP
0,207,529 A2) to provide not two, but merely one hook per warp thread, which
hook can in turn be coupled with one of two lifting knives moving in opposite
di-
rections. For this purpose, a control element is associated to each hook,
which
deflects the hook such that the hook, which in the low position is supported
on a
bottom board, can be hooked up in one of the two lifting knives or in a
holding
knife. Independent of whether the hooks are arranged singly or in pairs, these
known shedding apparatuses for jacquard machines have the disadvantage of
complex constructions, because the hooks must be adjusted by means of corre-
sponding control elements and must be coupled with one of two lifting knives
moving in opposite directions.
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Summary of the Invention
It is therefore the object underlying the invention to provide an apparatus
for
forming sheds for a jacquard machine as described above such that a consider-
able simplification of the construction and thus an increased functional
reliability
can be ensured.
This object is solved by the invention in that the driver stops of the lifting
means
can be swivelled from a stop-limited drive position into a rest position
outside the
path of movement of the counter-stops of the hooks, and that the control
elements
on the one hand have a cam track for swivelling the driver stops of the
lifting
means and on the other hand a holding stop for the hooks in the high position.
Due to the measure of pivotally mounting the driver stops of the lifting means
such
that these driver stops can selectively be adjusted via the associated control
ele-
ments, the connection of the hooks with the lifting means can easily be
controlled
without having to move the hooks themselves transverse to their path of move-
ment between the high position and the low position. When the driver stop for
the
respective hook to be actuated is in its stop-limited drive position, the
associated
hook can be moved into the respective other shed position via the lifting
means. It
must merely be ensured that in the respective shed position the hooks are sup-
ported against the tensile load which acts on them via the hook suspension
gear.
For the low position, this can be achieved in a conventional way, e.g. via a
bottom
board. In the high position, this is achieved by means of a holding stop of
the
control elements. Since it is merely between the high position and the low
position
that the hooks are movably guided in the frame on a straight line, retaining
the
actuated hook in the high position requires a corresponding control movement
of
the associated control element transverse to the path of movement of the
hooks.
By combining the pivotally mounted driver stops of the lifting means with
control
elements, which on the one hand adjust the driver stops of the lifting means
and
on the other hand form a holding stop for the hooks in the high position, all
control
tasks can thus advantageously be solved by one control element each associated
to the individual hooks.
Since in the low position of the hook the associated driver stop of the
lifting means
need merely be swivelled out into the rest position, to prevent the hooks from
be-
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ing driven, the control elements need to have cam tracks for the driver stops
merely in the vicinity of this low position, when it is ensured that the
driver stops of
the lifting means return into the stop-limited drive position outside the cam
tracks
of the control elements. For this purpose, the driver stops can be mounted
such
that they can be swivelled out of the stop-limited drive position against a
restoring
moment. Such restoring moment can be ensured by spring-loading the driver
stops. To obtain a higher functional reliability, a forced return of the
driver stops
into the stop-limited drive position should, however, also be effected in the
vicinity
of the high position. It is therefore recommended to equip the control
elements
with a cam track for swivelling the driver stops out of the stop-limited drive
posi-
tion in the vicinity of the low position, and with a cam track for swivelling
the driver
stops into the drive position in the vicinity of the high position, so that
spring-
loading the driver stops becomes superfluous.
There can be different adjusting movements of the control elements, because it
is
merely important to either provide the holding stop for the hooks in the high
posi-
tion by means of a transverse movement of the control elements, or to swivel
the
driver stops in particular in the vicinity of the low position. Nevertheless,
particu-
larly advantageous constructional conditions can be achieved in that the
control
elements are mounted on a common guiding axle via an inclined guiding slot and
can be retained in a raised end position by means of electromagnets. The
adjust-
ment of the control elements along an inclined guiding slot in which engages a
fixedly mounted guiding axle involves a combined movement of the control ele-
ments on the one hand transverse to and on the other hand in the direction of
the
path of movement of the hooks, so that the adjusting movement of the control
elements can be effected via the hooks or the driver stops of the lifting
means. In
this case, the electromagnets merely serve to retain the upper end position of
the
control elements.
It is, however, also possible to rotatably mount the control elements on a
common
swivel axis and swivel them via the hooks or the driver stops of the lifting
means,
in order to again ensure a corresponding control movement transverse to the
path
of movement of the hooks. However, rotatably mounting the control elements on
a
common swivel axis involves increasing regulating distances with increasing
dis-
tance from the swivel axis, which can be avoided with a parallel displacement
of
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the control elements. For retaining the swivelled-out end position of the
pivotally
mounted control elements, electromagnets can again be used.
For a better guidance above all of the control elements mounted on a guiding
axle
by means of guiding slots it is recommended to additionally guide the control
ele-
ments in particular with respect to the driver stops. For this purpose, the
lifting
means can form a lifting frame carrying the pivotally mounted driver stops,
where
the control elements are adjustably guided in this lifting frame, so that for
swivel-
ling the driver stops out into the rest position they cannot evade these
driver
stops.
Brief Description of the Drawing
In the drawing, the subject-matter of the invention is represented by way of
ex-
ample, wherein:
Figs. 1 to 4 show an inventive apparatus for forming sheds for a jacquard
machine
in a schematic side view in different working positions,
Figs. 5 to 7 show segments of different actuators for the control elements of
an
inventive apparatus in a simplified side view, and
Figs. 8 and 9 show an embodiment of an inventive apparatus, which is modified
with respect to Figs. 1 to 4, in a schematic side view in different work-
ing positions.
Description of the Preferred Embodiment
As can be taken from Figs. 1 to 4, the warp threads 1 forming the shed are
guided
through lugs 2 of a hook suspension gear 3, which in the embodiment is formed
by harness cords 4, but may also consist of heddles. With one end, these
harness
cords 4 are hooked up into a bottom board 5 and guided about a deflection
roller
6 of the respectively associated hook 7. With the other end, the harness cords
4
engage in associated tension springs 8, by means of which the harness cords 4
are kept taut independent of the respective position of the hook 7. Guiding
the
harness cords 4 over deflection rollers 6 of the hooks 7 involves the
advantage
that the lugs 2 are moved with the double path of movement of the hooks 7. The
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stroke of the lifting means 9 provided for moving the hooks 7 can therefore be
comparatively small.
The lifting means 9 for the hooks 7 includes a lifting frame 10 in which for
each
hook 7 a driver stop 11 is provided, which can be swivelled about an axis 12
be-
tween a stop-limited drive position and a rest position outside the path of
move-
ment of the counter-stops 13 of the hooks 7. This swivel movement is effected
by
means of control elements 14 associated to the individual hooks 7, which
control
elements are mounted on a common guiding axle 15 via an inclined guiding slot
16 and can be adjusted along their guiding slots 16, as shown in Figs. 1 to 4.
In
the upper end position, the control elements 14 can selectively be retained by
as-
sociated electromagnets 17. The control elements 14 each form a holding stop
18
for the hooks 7 in the upper high position, where the hooks 7 are supported on
the
associated holding stops 18 by means of a projection 19, as is shown in Fig.
1.
The control elements 14 in addition have a supporting arm 20 for a cam track
21,
which is used for swivelling the associated driver stop 11. In the position of
the
control element 14 as shown in Fig. 3, the pivotally mounted driver stop 11 of
the
lifting frame 10 slides onto the cam track 21 in the vicinity of the low
position, so
that the driver stop 11 is swivelled from the stop-limited drive position into
a rest
position outside the path of movement of the counter-stop 13 of the hook 7.
For
swivelling back the driver stop 11 released by the cam track 21 a dead weight
or a
restoring spring may be provided. To improve the functional reliability a
further
cam track 22 is, however, provided at the control element 14 in accordance
with
the illustrated embodiment, which further cam track ensures a forced
swivelling
back of the driver stops 11 in the vicinity of the high position, as can be
taken from
Fig. 2.
As has already been explained, in the position of the control element 14 as
shown
in Fig. 1, the hook 7 is held in the high position via the holding stop 18 of
the con-
trol element 14, whereas the lifting frame 10 is moved up and down. When it is
desired to move the hook 7 from the high position shown in Fig. 1 into a low
posi-
tion in accordance with Fig. 3 or 4, the control element 14 lifted by means of
the
lifting frame 10 is retained in its upper end position by the electromagnet
17,
which is energized via a control means, whereas the lifting frame 10
supporting
the hook 7 is moved into the low position. The movement of the control element
14 along the guiding slot 16 effects a release of the projection 19 of the
hook 7 by
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the holding stop 18. To ensure that upon reaching the bottom board 5 the hook
7
is not entrained into the upper high position with the lifting frame 19 again
moving
upwards, the driver stop 11 must be swivelled out of the path of movement of
the
counter-stop 13 of the hook into the rest position, which is achieved by the
control
element 14, which upon dropping off the electromagnet 17 protrudes into the
path
of the driver stop 11 with the cam track 21 and ensures the swivel movement of
said driver stop, as can be taken from Fig. 3.
The movement of the hooks 7 from the low position shown in Fig. 3 into a high
position shown in Fig. 1 is again effected by briefly energizing the
electromagnet
17, which during the downward movement of the lifting frame 10 retains the con-
trol element 14 in the upper end position, so that the driver stop 11 is not
swiv-
elled out into the rest position by the cam track 21. The driver stop 11
moving past
the counter-stop 13 of the hook 7 into the lower reversed position thus
entrains
the hook 7 during the upward movement of the lifting frame 10, as can be seen
in
Fig. 4. The hook 7 can therefore be lifted from the low position into the high
posi-
tion via the lifting means 9. Since holding the control element 14 is effected
via a
slotted guideway 16 on a guiding rod 15, and the supporting arm 20 of the
guiding
element 14 adjustably engages in a through hole 23 of the lifting frame 10
trans-
verse to the direction of movement of the hooks 7, the holding stops 18 of the
guiding elements 14 evade the projections 19 of the hooks 7 lifted by means of
the lifting means 9, in order to subsequently engage behind these projections
19.
The hooks 7 themselves are merely linearly movably guided in the frame and
cannot perform such evading movement.
As can be taken from Figs. 5 to 7, the control elements 14 can be mounted and
adjusted in different ways. The embodiment shown in Fig. 5 represents a
slotted
guideway of the control elements 14 corresponding to Figs. 1 to 4, but where
the
electromagnets 17 have lifting armatures 24, which are each connected with a
control element 14 and upon energizing the electromagnet 17 are tightened in
the
direction of the guiding slot 16, as is represented in broken lines. A
restoring
spring 25 ensures the starting position of the control elements 14 upon
energizing
the electromagnet 17.
Figs. 6 and 7 represent control elements 14 which are rotatably mounted about
a
common swivel axis 26. As shown in Fig. 6, an armature plate 27 associated to
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the control elements 14 is tightened by the respectively energized
electromagnet
17, so that the control element 14 is retained in the swivel position
indicated in
broken lines. As shown in Fig. 7, the electromagnets 17 are provided with
lifting
armatures 24 corresponding to Fig. 5, but where the lifting armatures 24 are
piv-
otally mounted at the control elements 14. A restoring spring 25 again moves
the
control element 14 into the starting position upon energizing the actuated
elec-
tromagnet.
In the embodiment shown in Figs. 1 to 4, the electromagnet 17 is each
energized
in order to move the hook from the given shed position into the respective
other
shed position. This means that the control of the respective shed position
must be
known in order to eliminate switching errors. As shown in Figs. 8 and 9, the
re-
spective energizing condition of the electromagnet 17 determines the shed posi-
tion. For this purpose, the cam track 21 of the control element 14 is designed
such
that in the upper end position of the control element 14 (Fig. 8), which is
held by
the electromagnet 17, the driver stop 11 is swivelled out into its rest
position,
which leads to the maintenance of the low position of the hook 7. For lifting
the
hook 7 into the high position, the electromagnet 17 must be deenergized, as is
represented in Fig. 9. Accordingly, the driver stop 11 is swivelled into the
drive
position, so that the hook 7 is raised by the lifting frame 10, until the
projection 19
of the hook 7 is moved past the holding stop 18 of the control element 14, so
that
during the subsequent downward movement of the lifting frame 10 the hook 7 is
retained in the high position by this holding stop 18.
