[0001] The invention relates to a drive and a method for driving a gripper
carrier for a bringer gripper and a gripper carrier for a taker gripper by
means of a drive, which comprises a common drive motor for two drive
mechanisms and two drive wheels each driven by an associated drive
mechanism for a gripper carrier, wherein the gripper carriers are driven so
that the bringer gripper and the taker gripper each reciprocate between an
outer reversing point situated outside the shed and an inner reversing point
situated inside the shed.
[0002] From DE 10346227 A 1 a drive mechanism for a gripper carrier is
known. In NL 751 1122 A, the drive wheel for the gripper carrier for the
bringer gripper and the drive wheel for the gripper carrier for the taker grip
per carry out a so-called "symmetrical" movement, in which the bringer
gripper and the taker gripper move towards one another in the opposite
direction, wherein the bringer gripper and the taker gripper meet one a n
other approximately in the center of the shed and wherein the bringer grip
per and the taker gripper subsequently move away from one another again
in the opposite direction. A gripper carrier may, for example, consist of a
gripper band or of a gripper bar.
[0003] In particular when gripper openers are used to open and/or close a
gripper clamp of a bringer gripper and/or a gripper clamp of a taker gripper
near the center of the shed, it is known to drive the bringer gripper and the
taker gripper with a so-called "asymmetrical" movement, in which more
time is available for the transfer of a weft thread. In the shed, the taker
gripper moves beyond the inner reversing point of the bringer gripper be
fore the bringer gripper has reached its inner reversing point, so that both
grippers move in the same direction and along the direction of insertion for
a short distance after the taker gripper has reached its inner reversing
point. In order to make this "asymmetrical" movement possible, it is known
from EP 0526390 A 1 to drive a gripper carrier by means of a programcontrolled
drive motor. This embodiment has the problem that the move
ment paths of the bringer gripper and the taker gripper are difficult to syn
chronize, as the variations in speed of the program-controlled drive motor
are difficult to control. In addition, the moving of the taker gripper along with
the bringer gripper during the transfer of the weft thread, requires that the
taker gripper and/or the bringer gripper travel a greater distance in the
shed, which is to say they have a higher mean velocity and are subjected
to greater accelerations in order to carry out the same number of insertions
per unit time.
[0004] The object of the invention is to improve an abovementioned me
thod in such a manner that an "asymmetrical" movement by a bringer
gripper and a taker gripper is maintained without independent drive motors
having to be provided for this purpose and wherein the bringer gripper and
the taker gripper may insert a weft thread at a relatively low speed.
[0005 ]This object is achieved in that, with respect to the weaving cycle, the
outer reversing point of the bringer gripper is ahead of the outer reversing
point of the taker gripper. The expression "with respect to the weaving cy
cle" is intended to mean with respect to the movement path of the weaving
machine as a function of time, more particularly with respect to the successive
angular positions of the weaving machine which are determined by the
successive angular positions of the common drive motor.
[0006] The invention not only has the advantage that a drive is provided
with a common drive motor for the bringer gripper and the taker gripper, but
also that the bringer gripper can enter the shed slower and that the taker
gripper can leave the shed slower. In this case, the movements of the brin
ger gripper and of the taker gripper are be dephased to such an extent that
the outer reversing point of the bringer gripper is ahead of the outer rever
sing point of the taker gripper by several machine degrees. In this case, the
bringer gripper does not necessarily enter the shed sooner and the taker
gripper does not necessarily leave the shed later. The invention is
particularly advantageous if the weaving machine is set to weave at maximunn
weaving width, more particularly if weaving takes place at virtually the
maximum weaving width. The method according to the invention allows,
when the weaving machine weaves at a certain speed, to move the bringer
gripper and the taker gripper at a relatively low speed at a certain weaving
width when they insert a weft thread, which is particularly advantageous
when weaving at relatively large weaving widths.
[0007] According to a preferred embodiment, the object of the invention is
achieved in that, at least at a setting for maximum weaving width, with re
spect to the weaving cycle, the outer reversing point of the bringer gripper
is ahead of the outer reversing point of the taker gripper.
[0008] According to one embodiment, the gripper carrier for the bringer
gripper and the gripper carrier for the taker gripper are driven at a variable
speed by the common drive motor of the drive during their movements into
the shed and out of the shed, wherein with respect to the weaving cycle,
the bringer gripper is accelerated less after the outer reversing point than
after the inner reversing point and wherein, with respect to the weaving cy
cle, the taker gripper is accelerated more after the outer reversing point
than after the inner reversing point. The expression "a movement into the
shed" is intended to mean that the bringer gripper and/or the taker gripper
move towards the inner reversing point, while the expression "a movement
out of the shed" is intended to mean that the bringer gripper and/or the
taker gripper move towards the outer reversing point. This method is par
ticularly advantageous since it allows to initially accelerate a bringer gripper
less while picking up a weft thread which is held ready outside the shed in
order to subsequently move at a higher speed in the shed. In this case, the
bringer gripper moves relatively slowly during picking up of a weft thread
and the taker gripper moves relatively slowly during the release of a weft
thread.
[0009] According to one embodiment, with respect to the weaving cycle,
the inner reversing point of the taker gripper is ahead of the inner reversing
point of the bringer gripper. According to one embodiment, the gripper carrier
for the bringer gripper and the gripper carrier for the taker gripper are
driven at variable speed by a common drive motor of the drive during their
movements into the shed and out of the shed, wherein with respect to the
weaving cycle, the bringer gripper before its inner reversing point and the
taker gripper after its inner reversing point move in the same direction over
a distance. Despite the variable speeds of the bringer gripper and the taker
gripper, it is ensured in this case that the bringer gripper and the taker grip
per meet each other near the center of the shed and move in the same d i
rection over a distance.
[0010] According to one embodiment, the outer reversing point of the brin
ger gripper is situated several machine degrees before the beat-up and the
outer reversing point of the taker gripper is situated several machine
degrees after the beat-up. The term "beat-up" in this case is intended to
mean the moment during the weaving cycle, more particularly, the angular
position of the weaving machine wherein a weft thread is beaten-up by the
weaving reed that is driven by the sley. The term "machine degrees" is in
this case intended to mean the degrees of the weaving machine which are
determined by the drive motor and which, for one weaving cycle, vary suc
cessively between 0° and 360°.
[001 1] According to one embodiment, the bringer gripper leaves the shed
a number of machine degrees before beat-up and the bringer gripper e n
ters the shed a number of, for example the same number of, machine d e
grees after beat-up, while the outer reversing point of the bringer gripper is
situated several machine degrees before beat-up. According to one embodiment,
the taker gripper leaves the shed a number of machine degrees
before beat-up and the taker gripper enters the shed within a number of, for
example the same number of, machine degrees after beat-up, while the
outer reversing point of the taker gripper is situated several machine de
grees after beat-up. In this way, it is ensured that despite the angular difference
between the outer reversing points, the bringer gripper and the
taker gripper can enter the shed as early as possible and can also leave
the shed as late as possible, wherein a required average speed of the
bringer gripper and/or of the taker gripper is relatively low for a given speed
of the weaving machine, that is to say at a given number of insertions per
unit time.
[0012] The object is further achieved by a drive for a gripper carrier for a
bringer gripper and for a gripper carrier for a taker gripper which drive com
prises a common drive motor for two drive mechanisms and two drive
wheels for a gripper carrier which are each driven by an associated drive
mechanism, wherein each drive mechanism comprises a crank which
drives a fork element, wherein the fork element and a cross element are
mounted rotatably with respect to one another via a shaft, wherein the
cross element is connected to a toothed segment which drives a drive
wheel for a gripper carrier and which, together with the cross element, is
mounted rotatably with respect to a frame of the drive mechanism, wherein
the cross element and the frame of the drive mechanism are mounted rotatably
with respect to one another via a shaft which is arranged trans
versely to the shaft by means of which the fork element and the cross ele
ment are mounted rotatably with respect to one another, wherein each
crank is driven in a rotationally fixed manner by the common drive motor at
a certain angular position with respect to the angular position of the common
drive motor and wherein, for each drive mechanism associated with a
drive wheel, the two shafts assigned to the cross element are arranged at
an angle with respect to one another which deviates by a few angular d e
grees from 90° and/or, for each drive mechanism associated with a drive
wheel, the crank is driven in a rotationally fixed manner at a certain angular
position with respect to the angular position of the common drive motor, in
such a manner that, with respect to the weaving cycle, the outer reversing
point of the bringer gripper is ahead of the outer reversing point of the taker
gripper.
[0013] The adjusting according to the invention of the angles between
each crank and associated fork element, of the angles between the two
shafts assigned to each cross element and of the angular positions in
which each crank is driven with respect to the common drive motor results
in the advantage of an asymmetrical gripper movement being achieved
with a common drive motor, wherein the bringer gripper and the taker grip
per are still able to insert a weft thread in a shed at a relatively low speed
and with relatively low accelerations. This is particularly advantageous
when the weaving machine weaves at high speeds and with large weaving
widths.
[0014] According to a preferred embodiment, the two shafts assigned to
the cross element are fitted on the cross element, more particularly are
formed as a single part with the cross element. A drive having a common
drive motor for two drive wheels driven by an associated drive mechanism
allows both drive wheels to be moved with respect to the weaving cycle as
a function of the angular position of the drive motor and as a function of the
properties of the drive mechanism according to the invention. The expres
sion "driven in a rotationally fixed manner" is intended to mean that the
course of the angular position of the drive mechanism is determined by the
course of the angular position of the drive motor.
[0015] According to one embodiment, the two shafts assigned to the cross
element are arranged at an angle with respect to one another which devi
ates by a few angular degrees from 90°, i.e. the shaft by means of which
the fork element and the cross element are mounted rotatably with respect
to one another forms an angle which deviates from 90° with the shaft, by
means of which the cross element and the frame for the drive mechanism
are mounted rotatably with respect to one another, in such a manner that,
with respect to the weaving cycle, the bringer gripper is accelerated less
after the outer reversing point than after the inner reversing point and that
the taker gripper is accelerated more after the outer reversing point than
after the inner reversing point. With respect to the weaving cycle, this a l
lows that the bringer gripper and the taker gripper may enter the shed as
early as possible and also may leave the shed as late as possible.
[0016] According to one embodiment, the two shafts assigned to the cross
element are arranged at an angle with respect to one another which deviates
by a few angular degrees from 90° and/or the angular positions of the
cranks of the drive mechanisms are set with respect to the angular position
of the drive motor in such a manner that, with respect to the weaving cycle,
the gripper carrier for the bringer gripper and the gripper carrier for the
taker gripper are driven at variable speed by the drive during their move
ments into the shed and out of the shed, wherein with respect to the weav
ing cycle, the bringer gripper before its inner reversing point and the taker
gripper after its inner reversing point move over a distance in the same d i
rection.
[0017] According to one embodiment, the two shafts assigned to the cross
element are arranged at an angle with respect to one another which devi
ates by a few angular degrees from 90° and/or the angular positions of the
cranks of the drive mechanisms are set with respect to the angular position
of the drive motor in such a manner that, with respect to the weaving cycle,
the inner reversing point of the taker gripper is ahead of the inner reversing
point of the bringer gripper.
[0018] According to one embodiment, the two shafts assigned to the cross
element are arranged at an angle with respect to one another which devi
ates by a few angular degrees from 90° and/or the angular positions of the
cranks of the drive mechanisms are set with respect to the angular position
of the drive motor in such a manner that the outer reversing point of the
bringer gripper is situated several machine degrees before beat-up and
that the outer reversing point of the taker gripper is situated several ma
chine degrees after beat-up.
[0019] According to one embodiment, the two shafts assigned to the cross
element are arranged at an angle of approximately 4° displaced with re
spect to an angle of 90°.
[0020] According to one embodiment, the shaft, by means of which the
fork element and the associated crank are mounted rotatably with respect
to one another, forms an angle which deviates by a few angular degrees
from 45°, for example an angle of approximately 48°, with the shaft by
means of which the cross element and the fork element are mounted rotatably
with respect to one another. This allows the bringer gripper and the
taker gripper to be moved, with respect to a weaving cycle, over a desired
distance in the shed.
[0021] With such a drive mechanism, the shaft which connects the crank
and the fork element and the two shafts assigned to the cross element pref
erably pass through a common point.
[0022] According to one embodiment, the cranks of the two drive mechanisms
are driven in a rotationally fixed manner by a common drive shaft,
wherein the crank of the drive mechanism for the bringer gripper is a r
ranged, in the drive direction of the drive shaft, so that it is ahead of the
crank of the drive mechanism for the taker gripper by a few machine de
grees. According to one embodiment, the drive mechanism for the bringer
gripper and the drive mechanism for the taker gripper are of identical de
sign. This makes an easy assembly of a drive for a weaving machine pos
sible.
[0023] The object is furthermore achieved by a weaving machine which
comprises a drive according to the invention.
[0024] Further features and advantages of the invention will become clear
from the following description of the exemplary embodiments which are
illustrated in the drawings. The illustrated exemplary embodiments are only
intended to explain the invention. Variants and combinations of the illus
trated exemplary embodiments which are covered by the scope of protection
of the claims are likewise possible.
[0025] Figure 1 shows a perspective view of a drive for a gripper band
for a bringer gripper and for a gripper band for a taker
gripper,
Figure 2 shows an enlarged view of a drive mechanism for a
drive wheel for a gripper band according to Figure 1
with a crank, a fork element, a cross element and a
toothed segment,
Figure 3 shows a top view along arrow A from Figure 1 of the
drive mechanism according to Figure 2,
Figure 4 shows a top view along arrow D from Figure 1 of the
other drive mechanism from Figure 1,
Figure 5 shows a side view along arrow B from Figure 1 of the
drive mechanism according to Figure 2,
Figure 6 shows another perspective view along arrow C from
Figure 1 of the drive mechanism according to Figure 2,
Figure 7 shows a perspective view of the cross element accord
ing to Figures 1 to 6,
Figure 8 shows a top view of the cross element along arrow E
from Figure 7,
Figure 9 shows a side view of the fork element according to
Figures 1 to 6,
Figure 10 shows a top view of the drive shaft with gear wheels
along arrow F from Figure 1,
Figure 11 shows a diagram of the movement path of the bringer
gripper and the taker gripper between the outer revers
ing points which are situated outside a shed, and the
inner reversing points which are situated inside a shed,
Figure 12 shows a part of a diagram of the movement path of the
bringer gripper and the taker gripper in the vicinity of
the outer reversing points,
Figure 13 shows a variant of Figure 11, in which weaving takes
place at a more limited weaving width than in Figure
11.
026] Figure 1 shows a drive 1 for a gripper carrier 2 for a bringer gripper
and for a gripper carrier 4 for a taker gripper 5 . Such a drive 1 may be
used in a weaving machine, in particular in a gripper weaving machine. The
drive 1 comprises a common drive motor 6 which drives two gear wheels 8
and 9 via a drive shaft 7 . The drive mechanism 10 which drives the drive
wheel 14 for the gripper carrier 2 is driven by the drive motor 6 via the gear
wheel 8, while the drive mechanism 11 which drives the drive wheel 15 for
the gripper carrier 4 is driven by the drive motor 6 via the gear wheel 9 .
[0027] Figures 1, 2, 3, 5 and 6 show the drive mechanism 10 which com
prises a gear wheel 12 which can be driven by the gear wheel 8, a crank
13 connected to the gear wheel 12, a fork element 16 assigned to the
crank 13 and a cross element 17 assigned to the fork element 16 . The
cross element 17 is connected to a toothed segment 22 which can drive
the drive wheel 14 for the bringer gripper 3 via a gear wheel transmission
18 . Such a crank 13 and gear wheel transmission 18 are known, for exam
ple, from DE 10346227 A 1. The crank 13 can be connected to the gear
wheel 12 via a bearing half 19, illustrated in Figure 6, in an adjustable posi
tion, in such a manner that the crank 13 is arranged rotatably to the gear
wheel 12. Via a shaft 23 with an axis 43, illustrated in Figure 5, the crank
13 drives the fork element 16, wherein the crank 13 and the fork element
16 are mounted rotatably with respect to one another via the shaft 23. The
cross element 17 is driven by the fork element 16 via a shaft 20 with an
axis 44, illustrated in Figures 3 and 5, which is mounted in the fork element
16, wherein the fork element 16 and the cross element 17 are mounted
rotatably with respect to one another via the shaft 20. The cross element 17
is together with the toothed segment 22 mounted rotatably about a shaft 2 1
with an axis 45, illustrated in Figure 3, which shaft 2 1 is arranged trans
versely with respect to the shaft 20. The shaft 2 1 is mounted rotatably with
respect to a frame 42, wherein the cross element 17 and the frame 42 are
mounted rotatably with respect to one another via the shaft 2 1.
[0028] In the illustrated embodiment, the frame 42 can be fixedly attached
to the frame (not shown) of the drive mechanism 10 of the weaving ma
chine. In the drive mechanism 10, the axes 43, 44 and 45 of the respective
shafts 23, 20 and 2 1 pass through a common point 36, as is illustrated in
Figures 3 and 5 .
[0029] As is illustrated in Figures 7 and 8, the shaft 2 1 is formed by two
axle stubs 56 and 57 which are fitted on the cross element 17 and which
can be mounted with respect to the frame 42 via bearings 58, 59, which are
illustrated in Figures 3, 5 and 6. In this case, the shaft 20 is formed by two
axle stubs 24 and 25 which are fitted on the cross element 17 and which
can be mounted with respect to the fork element 16 via bearings. As is
illustrated in Figures 3, 5, 6 and 9, the fork element 16 comprises two legs
60 and 6 1, in which an axle stub 24 or 25 can be mounted, respectively.
[0030] As can be seen in Figures 5 and 9, the shaft 23 with axis 43 by
means of which the fork element 16 and the crank 13 are mounted rotata
bly with respect to one another forms an angle 53 which deviates by a few
angular degrees from 45°, for example an angle of approximately 48°, with
respect to the shaft 20 with axis 44 by means of which the cross element
17 and the fork element 16 are mounted rotatably with respect to one a n
other.
[0031] Figure 4 shows a top view along arrow D from Figure 1 of the drive
mechanism 11 which is of identical design to the drive mechanism 10, but
is arranged angularly offset about 180° with respect to the drive mecha
nism 10. As can be seen in Figures 1, 3 and 4, the drive mechanisms 10
and 11 are arranged in such a manner that the axis 44 of the shaft 20 of
the drive mechanism 10 and the axis 50 of the shaft 48 of the drive mecha
nism 11 are arranged virtually parallel to one another, in a top view. The
gear wheel 26 of the drive mechanism 11 is driven via the gear wheel 9
and the toothed segment 47 of the drive mechanism 11 drives the drive
wheel 15 for the taker gripper 5 via a gear wheel transmission 27. Analo
gously to what is illustrated in Figure 5 and as indicated in Figure 1, the
axis 62 of the shaft 55 by means of which the fork element 54 and the
crank 28 are mounted rotatably with respect to one another forms an angle
63 of approximately 48° with respect to the axis 50 of the shaft 48 by
means of which the cross element 52 and the fork element 54 are mounted
rotatably with respect to one another.
[0032] According to the invention and as indicated in Figures 1, 3, 4, 7 and
8, the shafts 20 and 2 1 with axes 44 and 45 and the shafts 48 and 49 with
axes 50 and 5 1 of each cross element 17 and 52 for each drive mechanism
10 and 11 are arranged at an angle 37, 64 with respect to one another
which deviates by a few angular degrees from 90°. The perpendicular 82,
83 to the shafts 45 and 5 1 is illustrated in the Figures 3, 4, 7 and 8 as a
dot-dashed line. In the illustrated embodiment, the shafts 20 and 2 1 and
the shafts 48 and 49 of each cross element 17, 52 are arranged at an a n
gle 37 and 64, respectively, of approximately 4° displaced with respect to
an angle of 90°.
[0033] By adjusting the mutual angular position of the drive mechanism 10
with respect to the drive motor 6, for example by mutual adjustment of the
gear wheels 8 and 12 and the mutual adjustment of the gear wheel 8 and
the drive shaft 7, the crank 13 can be driven by the drive motor 6 in a cer
tain angular position with respect to the angular position of the drive motor
6 . During weaving, the gear wheels 12 and 26 are driven by the drive motor
6 in the drive direction R.
[0034] The gear wheel 12 to which the crank 13 of the drive mechanism
10 is attached and the gear wheel 26 to which the crank 28 of the drive
mechanism 11 is attached are set angularly displaced by angles 67 and 68
with respect to a reference position, for example a reference position de
termined by an angular position wherein the crank 13, 28 is attached to a
gear wheel 12, 26 and thus set at a certain angular position with respect to
the angular position of the drive motor 6, as is illustrated in Figure 1, so that
the cranks 13 and 28 of the two drive mechanisms 10 and 11 are driven in
associated angular positions by the drive motor 6 via the drive shaft 7 in a
rotationally fixed manner and dephased with respect to one another.
[0035] As is illustrated in Figure 1 and 10, the gear wheel 8 can be fitted to
this end to the drive shaft 7 via a clamping connection 65 and the gear
wheel 9 via a clamping connection 66. Each clamping connection 65, 66
allows the gear wheel 8, 9 to be fixedly attached in a certain angular position
with respect to the drive shaft 7, so that both gear wheels 8, 9 can be
attached in a certain mutual angular position with respect to the drive shaft
7 . According to a variant (not shown), one of the abovementioned gear
wheels can be formed as a single part with the drive shaft 7, while the other
gear wheel can be connected to the drive shaft 7 via an abovementioned
clamping connection. As a result thereof, the angular positions of the
cranks 13, 28 of the drive mechanisms 10, 11 can be set with respect to
the angular position of the drive motor 6, so that the mutual angular posi
tion between the cranks 13, 28 can be set.
[0036] According to a variant, the drive shaft 7 can be formed by two shaft
ends which are arranged in line with one another and which can be co n
nected to one another by a clamping connection 84, as indicated schemati
cally by a dashed line in Figure 10, in different mutual angular positions,
wherein each time one of the gear wheels 8, 9 is fitted on one of the shaft
ends, so that the mutual angular position between the gear wheels 8, 9 and
thus also between the cranks 13, 28 can be set.
[0037] According to a variant as indicated by a dashed line in Figure 1, a
drive shaft 85 may be provided on which the gear wheels 12 and 26 are
fitted. In this case, the gear wheel 12 may, for example, be formed as a
single part with the drive shaft 85, and the gear wheel 26 may be connected
to the drive shaft 85 via a clamping connection. The gear wheel 12
is in this case driven by the drive motor 6 via the gear wheel 8, while the
gear wheel 26 is driven by the drive motor 6 via the gear wheel 8, the gear
wheel 12 and the drive shaft 85. In this variant, the gear wheel 9, the
clamping connection 66 and the part of the drive shaft 7 situated between
the gear wheel 8 and the gear wheel 9 may be omitted.
[0038] As is illustrated in Figure 1, the bringer gripper 3 and the taker grip
per 5 are intended to move into and out of a shed 29. A shed 29 is formed
by planes of warp threads 30 and 3 1 which converge at the location of the
beat-up line 32 of the fabric 33. The drive mechanisms 10 and 11 allow the
bringer gripper 3 and the taker gripper 4 each to reciprocate between an
outer reversing point situated outside the shed 29 and an inner reversing
point situated inside the shed 29. By the design of the drive mechanisms
10 and 11, the gripper carrier 2 for the bringer gripper 3 and the gripper
carrier 4 for the taker gripper 5 move at a variable speed with respect to the
weaving cycle when these are driven by the drive motor 6 of the drive 1 in
the drive direction R. As a result thereof, the bringer gripper 3 and the taker
gripper 5 move at a variable speed during their movements into the shed
29 and out of the shed 29.
[0039] In Figure 11, a diagram of a movement path 38 of a bringer gripper
3 and a movement path 39 of a taker gripper 5 is shown. In Figure 12, the
movement path 38 of the bringer gripper 3 and the movement path 39 of
the taker gripper 4 are shown, in the vicinity of the outer reversing points I,
III.
[0040] These movement paths 38 and 39 can be achieved with the drive
mechanisms 10 and 11, as illustrated in Figures 1 to 10 . The arrangement
of the shafts 20 and 2 1, the shafts 48 and 49 and/or the setting of the mu
tual angular position between the gear wheels 12 and 26 with respect to
the drive motor 6, allow to achieve a movement path 38 or 39 wherein with
respect to the weaving cycle, i.e. according to the drive direction R of the
drive motor 6, the outer reversing point I of the bringer gripper 3 is ahead of
the outer reversing point III of the taker gripper 5 . In this exemplary em
bodiment, the reversing point I is ahead of the reversing point III by an a n
gular difference 40, wherein this angular difference is for example approxi
mately 18°. At a constant driving speed of the drive motor 6, this angular
difference 40 corresponds to a certain time difference. In the example illus
trated in Figure 1, in relation to the drive shaft 7, the crank 13 of the drive
mechanism 10 for the bringer gripper 3, which is driven via the gear wheels
8 and 12, is fitted so that it is ahead with respect to the crank 28 of the
drive mechanism 11 for the taker gripper 5 by some machine degrees,
which is driven via the gear wheels 9 and 26. The being ahead of the outer
reversing point I of the bringer gripper 3 with respect to the outer reversing
point III of the taker gripper 5 is also achieved by the drive mechanisms 10
and 11, more particularly by the angle 37 between both shafts 20 and 2 1 of
the cross element 17 of the drive mechanism 10 and/or the angle 64 be
tween both shafts 48 and 49 of the cross element 52 of the drive mecha
nism 11.
[0041] As is illustrated in Figures 11 and 12, the outer reversing point I of
the bringer gripper 3 is situated several machine degrees, for example 8°,
before beat-up 34 and the outer reversing point III of the taker gripper 5 is
situated several machine degrees, for example 10°, after beat-up 34. In this
case, the beat-up 34 corresponds to the angular position 0° or 360° of the
weaving machine or the moment in the weaving cycle wherein a weft
thread is beaten up. As is shown in Figures 11 and 12, with respect to the
weaving cycle, the bringer gripper 3 is accelerated less after the outer re
versing point I than after the inner reversing point I I and the taker gripper 5
is accelerated more after the outer reversing point III than after the inner
reversing point IV. As a result thereof, the bringer gripper 3 near the outer
reversing point I and the taker gripper 5 near the inner reversing point IV
are accelerated less, when they interact with the weft thread, which is ad
vantageous for inserting a weft thread into a shed 29 by means of a bringer
gripper 3 and a taker gripper 5 .
[0042] Figure 11 also shows that, with respect to the weaving cycle, the
inner reversing point IV of the taker gripper 5 is ahead of the inner revers
ing point I I of the bringer gripper 3 . In this exemplary embodiment, the
reversing point IV is ahead of the reversing point I I by an angular difference
4 1, wherein this angular difference is, for example, approximately 10°. In
this case, with respect to the weaving cycle, the bringer gripper 3 before its
inner reversing point I I and the taker gripper 5 after its inner reversing point
IV move in the same direction over a distance 35, more particularly along
the direction of insertion of the weft thread, which distance 35 is determined
by the angular difference 4 1.
[0043] In Figure 12, the hatched area 69 is determined by the angular po
sitions in machine degrees in the weaving cycle and the longitudinal positions,
i.e. positions with respect to the weaving width, in which a weaving
reed 86 which is schematically illustrated in Figure 1 moves near the beatup
34 up to a beat-up line 32 and beyond the movement path 87, indicated
in Figure 1 by a dot-dashed line, of the bringer gripper 3 and/or of the taker
gripper 4 . During weaving, the weaving reed 85 moves between the beatup
line 32 and a rearmost position. In Figure 1, the weaving reed 85 is illus
trated in the rearmost position. During the weaving cycle, the bringer grip
per 3 and the taker gripper 4, from the angular position 70 to the angular
position 7 1, may not be situated between the longitudinal positions 76 and
77 in the shed 29, as these could otherwise come into contact with the
weaving reed 86 or with the warp threads 30, 3 1. Although the outer
reversing point I of the bringer gripper 3 is several machine degrees ahead
of the beat-up 34, in this embodiment, the bringer gripper 3 and the taker
gripper 4 leave the area 69 at the angular position 70 and they enter the
area 69 at the angular position 7 1, wherein the angular positions 70 and 7 1
are each situated, for example, an identical number of machine degrees
away from the beat-up 34. Although the number of machine degrees 72
and 73, and 74 and 75, respectively, are different, the number of machine
degrees 78 and 79, and 80 and 8 1, respectively, are identical. According to
this embodiment, the available machine degrees are used in an optimum
manner in order to achieve a relatively low average speed of the bringer
gripper 3 and/or the taker gripper 4 for a certain number of insertions per
unit time, while a weft thread can be inserted into a shed 29 by the bringer
gripper 3 and the taker gripper 4 at a relatively low speed and acceleration.
[0044] If weaving is carried out with a limited weaving width, the setting of
the crank 13 with respect to the gear wheel 12 and/or the setting of the
crank 28 with respect to the gear wheel 26 can be changed slightly. In this
case, the setting of the gear wheel 8 with respect to the drive shaft 7 and/or
the setting of the gear wheel 9 with respect to the drive shaft 7 can also be
changed. Alternatively or in addition, it is also possible to change the mesh
ing position of the teeth of the gear wheel 8 and/or the meshing position of
the teeth of the gear wheel 9 with respect to the teeth of the associated
gear wheel 12 or 26. Such a meshing position may, for example, be
changed by displacing a gear wheel 8, 9 axially with respect to the drive
shaft 7 until the teeth of the gear wheel 8, 9 no longer mesh with teeth of a
gear wheel 12, 26, and by subsequently allowing the teeth of the gear
wheel 8, 9 to mesh with other teeth of a gear wheel 12, 26. Such adjustments
can be carried out in such a manner that the features of the claims
are met.
[0045] Figure 13 shows a variant for weaving at a more limited weaving
width. In this case, for example in the drive mechanism 11, the position of
the crank 28 with respect to the bearing half 19 is adjusted in such a way
that, with respect to the movement course according to the setting of Figure
11, the movement course 46 along which the taker gripper 5 is moved is
reduced. With the illustrated drive mechanism 11, this results in the fact
that, with respect to the weaving cycle, the outer reversing point I of the
bringer gripper 3 is less ahead of the outer reversing point III of the taker
gripper 5 than in the embodiment according to Figure 11. In the embodi
ment of Figure 13, the angle by which the outer reversing point I of the
bringer gripper 3 is ahead of the outer reversing point III of the taker gripper
5 can be increased again by suitably setting the angular positions of at
least one of the cranks 13, 28 with respect to the angular position of the
drive motor 6, for example by attaching the gear wheels 8 or 9 on the drive
shaft 7 at a suitable angular position.
[0046] It is clear that the fork element 16, 54 and the cross element 17, 52
of both drive mechanisms 10, 11 do not necessarily have to be of identical
design. Of course, the crank 13 and the crank 28 do not have to be of identical
design either and the same is true for the angles 37 and 64 and for the
angles 53 and 63. The angles 67 and 68 can also be suitably chosen. In
addition, the gear wheels 8 and 9 and the gear wheels 12 and 26 do not
necessarily have to be of identical design. According to a variant (not
shown), these can also be designed to be slightly different in order to sat
isfy the features of the claims.
[0047] The invention is particularly suitable for use with relatively wide
weaving machines and with weaving machines wherein the bringer gripper
3 and/or the taker gripper 4 are opened positively during gripping, change
over or release of the weft thread. This positive opening can be carried out
with devices which act on the clamp of a respective bringer gripper 3 or
taker gripper 5. Such devices are known, inter alia, from GB 2059455 and
EP 0526390 A 1.
[0048] The drive 1 according to the invention has the particular advantage
that the speed and the acceleration of the bringer gripper 3 are relatively
limited during gripping of a weft thread. In addition, the speed and the ac
celeration of the taker gripper 5 can be relatively limited during the release
of the weft thread. As the drive 1 according to the invention allows the
bringer gripper 3 and the taker gripper 5 to move in the same direction and
at virtually the same speed for a certain period of time during the change
over, more particularly allows them to perform an overlapping movement,
there is sufficient time available to changeover a weft thread in a satisfactory
manner from the bringer gripper 3 to the taker gripper 5. By means of a
drive 1 according to the invention, the bringer gripper 3 and the taker grip
per 5 are more accelerated and/or slowed down when they do not cooper
ate with the weft thread than when they do cooperate with the weft thread,
which allows to insert weft threads into a shed 29 at a reduced tension.
[0049] If the taker gripper 5 has smaller dimensions than the bringer grip
per 3, the taker gripper 5 can enter the shed 29, for example, sooner than
the bringer gripper 3 and during opening of the shed 29. In this case, the
taker gripper 5 can also leave the shed 29 later than the bringer gripper 3
and during the closing of the shed 29. If the taker gripper 5 has smaller dimensions
than the bringer gripper 3, the taker gripper 5 can enter the shed
29, for example, sooner than the bringer gripper 3 and while the weaving
reed is moving away from the beat-up line 32. In this case, the taker gripper
5 can also leave the shed 29 later than the bringer gripper 3 and while the
weaving reed is moving towards the beat-up line 32.
[0050] A weaving machine according to the invention allows that, at a certain
speed of the weaving machine, the taker gripper 5 moves through the
shed 29 over a larger movement course than the movement course with
which the bringer gripper 3 moves through the shed 29, while both the
bringer gripper 3 and the taker gripper 5, on average, move at a lower
speed through the shed 29 when they are inserting a weft thread into the
shed 29 than when they move through the shed 29 without a weft thread.
Claims
1. A method for driving a gripper carrier (2) for a bringer gripper (3) and
a gripper carrier (4) for a taker gripper (5) by means of a drive ( 1 ) ,
which drive ( 1) comprises a common drive motor (6) for two drive
mechanisms ( 10, 11) and two drive wheels (14, 15) each driven by
an associated drive mechanism ( 10, 11) for a gripper carrier (2, 4),
wherein the gripper carriers (2, 4) are driven so that the bringer grip
per (3) and the taker gripper (4) each reciprocate between an outer
reversing point (I, III) situated outside the shed (29) and an inner reversing
point (II, IV) situated inside the shed (29), characterized in
that, with respect to the weaving cycle, the outer reversing point (I)
of the bringer gripper (3) is ahead of the outer reversing point (III) of
the taker gripper (5).
2 . The method as claimed in claim 1, characterized in that the gripper
carrier (2) for the bringer gripper (3) and the gripper carrier (4) for
the taker gripper (5) are driven at variable speed by the drive ( 1) dur
ing their movements into the shed (29) and out of the shed (29),
wherein with respect to the weaving cycle, the bringer gripper (3) is
accelerated less after the outer reversing point (I) than after the inner
reversing point (II), and the taker gripper (5) is accelerated more
after the outer reversing point (III) than after the inner reversing point
(II).
3 . The method as claimed in claim 1 or 2, characterized in that, with
respect to the weaving cycle, the inner reversing point (IV) of the
taker gripper (5) is ahead of the inner reversing point (II) of the
bringer gripper (3).
4 . The method as claimed in one of claims 1 to 3, characterized in that
the gripper carrier (2) for the bringer gripper (3) and the gripper car
rier (4) for the taker gripper (5) are driven at variable speed by the
drive ( 1 ) during their movements into the shed (29) and out of the
shed (29), wherein with respect to the weaving cycle, the bringer
gripper (3) before its inner reversing point (II) and the taker gripper
(5) after its inner reversing point (IV) move in the same direction
over a distance.
The method as claimed in one of claims 1 to 4, characterized in that
the outer reversing point (I) of the bringer gripper (3) is situated sev
eral machine degrees before beat-up (34) and in that the outer re
versing point (IV) of the taker gripper (5) is situated several machine
degrees after beat-up (34).
A drive for a gripper carrier (2) for a bringer gripper (3) and for a
gripper carrier (4) for a taker gripper (5) which drive comprises a
common drive motor (6) for two drive mechanisms ( 10, 11) and two
drive wheels (14, 15) for a gripper carrier (2, 4) which are each
driven by an associated drive mechanism ( 10, 11) , wherein each
drive mechanism ( 10, 11) comprises a crank ( 13, 28) which drives a
fork element ( 16, 54), wherein the fork element ( 16, 54) and a cross
element ( 17, 52) are mounted rotatably with respect to one another
via a shaft (20, 48), wherein the cross element ( 17, 52) is connected
to a toothed segment (22, 47) which drives a drive wheel (14, 15) for
a gripper carrier (2, 4) and which, together with the cross element
( 17, 52), is mounted rotatably with respect to a frame (42), wherein
the cross element ( 17, 52) and the frame (42) are mounted rotatably
with respect to one another via a shaft (21 , 49) which is arranged
transversely to the shaft (20, 48) by means of which the fork element
( 16, 54) and the cross element ( 17, 52) are mounted rotatably with
respect to one another, wherein each crank ( 13, 28) is driven in a rotationally
fixed manner by the common drive motor (6) at a certain
angular position with respect to the angular position of the common
drive motor (6), characterized in that, for each drive mechanism
( 10, 11) associated with a drive wheel ( 14, 15), the two shafts
(20, 2 1; 48, 49) assigned to the cross element ( 17, 52) are arranged
at an angle (37, 64) with respect to one another which deviates by a
few angular degrees from 90° and/or in that, for each drive mecha
nism ( 10, 11) associated with a drive wheel ( 14, 15), the crank
( 13, 28) is driven in a rotationally fixed manner at a certain angular
position with respect to the angular position of the common drive
motor (6), in such a manner that, with respect to the weaving cycle,
the outer reversing point (I) of the bringer gripper (3) is ahead of the
outer reversing point (III) of the taker gripper (5).
The drive as claimed in claim 6, characterized in that the two shafts
(20, 2 1; 48, 49) assigned to the cross element ( 17, 52) are arranged
at an angle (37, 64) with respect to one another which deviates by a
few angular degrees from 90°, in such a manner that, with respect to
the weaving cycle, the bringer gripper (3) is accelerated less after
the outer reversing point (I) than after the inner reversing point (II)
and that the taker gripper (5) is accelerated more after the outer re
versing point (III) than after the inner reversing point (IV).
The drive as claimed in claim 6 or 7, characterized in that the two
shafts (20, 2 1; 48, 49) assigned to the cross element ( 17, 52) are a r
ranged at an angle (37, 64) with respect to one another which dev i
ates by a few angular degrees from 90° and/or the angular positions
of the cranks ( 13, 28) of the drive mechanisms ( 10, 11) are set with
respect to the angular position of the drive motor (6) in such a man
ner that, with respect to the weaving cycle, the gripper carrier (2) of
the bringer gripper (3) and the gripper carrier (4) of the taker gripper
(5) are driven at variable speed by the drive ( 1 ) during their move
ments into the shed (29) and out of the shed (29), wherein with re
spect to the weaving cycle, the bringer gripper (3) before its inner
reversing point (II) and the taker gripper (5) after its inner reversing
point (IV) move over a distance (35) in the same direction.
The drive as claimed in one of claims 6 to 8, characterized in that
the two shafts (20, 2 1; 48, 49) assigned to the cross element
( 17, 52) are arranged at an angle (37, 64) with respect to one another
which deviates by a few angular degrees from 90° and/or the
angular positions of the cranks ( 13, 28) of the drive mechanisms
( 10, 11) are set with respect to the angular position of the drive mo
tor (6) in such a manner that, with respect to the weaving cycle, the
inner reversing point (IV) of the taker gripper (5) is ahead of the in
ner reversing point (II) of the bringer gripper (3).
The drive as claimed in one of claims 6 to 9, characterized in that
the two shafts (20, 2 1; 48, 49) assigned to the cross element
( 17, 52) are arranged at an angle with respect to one another which
deviates by a few angular degrees from 90° and/or the angular posi
tions of the cranks ( 13, 28) of the drive mechanisms ( 10, 11) are set
with respect to the angular position of the drive motor (6) in such a
manner that the outer reversing point (I) of the bringer gripper (3) is
situated several machine degrees before beat-up (34) and that the
outer reversing point (IV) of the taker gripper (5) is situated several
machine degrees after beat-up (34).
The drive as claimed in one of claims 6 to 10, characterized in that
the two shafts (20, 2 1; 48, 49) assigned to the cross element
( 17, 52) are arranged at an angle of approximately 4° displaced with
respect to an angle of 90°.
The drive as claimed in one of claims 6 to 11, characterized in that
the shaft (23, 55), by means of which the fork element ( 16, 54) and
the associated crank ( 13, 28) are connected rotatably with respect to
one another, forms an angle which deviates by a few angular d e
grees from 45°, more particularly an angle of approximately 48°, with
the shaft (20, 48) by means of which the cross element ( 17, 52) and
the fork element ( 16, 54) are connected rotatably with respect to one
another.
The drive as claimed in one of claims 6 to 12, characterized in that
the cranks ( 13, 28) of the two drive mechanisms ( 10, 11) are driven
in a rotationally fixed manner by a common drive shaft (7), wherein
with respect to the weaving cycle, the crank ( 13) of the drive mecha
nism (10) for the bringer gripper (3) is fitted in such a manner that it
is ahead of the crank (28) of the drive mechanism ( 11) for the taker
gripper (3) by a few machine degrees.
14. The drive as claimed in one of claims 6 to 13, characterized in that
the drive mechanism ( 10) for the bringer gripper (3) and the drive
mechanism ( 1 1) for the taker gripper (5) are of identical design.
15.A weaving machine, characterized in that the weaving machine
comprises a drive ( 1 ) as claimed in one of claims 6 to 14.