TECHNICAL FIELD AND PRIOR ART
The invention relates to a fork-element for a gripper drive system for a weaving machine, to a
fork-element system, and to a gripper drive system comprising a fork-element and/or a fork5 element system.
A gripper drive system comprising a fork-element is shown for example in EP 4 008 817 A1. The
gripper drive system drives a rapier drive wheel to oscillate back-and-forth upon rotation of a drive
shaft of the weaving machine. The gripper drive system comprises a disk rotating with the drive
shaft of the weaving machine, a crank connected to the disk, the fork-element rotatably mounted
10 on the crank, a cross-element rotatably mounted on the fork-element, and a gear segment fixedly
connected to the cross-element, wherein the cross-element with the gear segment upon rotation
of the disk is driven to oscillate back-and-forth about a gear segment axis.
SUMMARY OF THE INVENTION
It is an object of the invention to provide a light-weight fork-element for a gripper drive system
15 without decreasing a strength of the fork-element. Further objects of the invention are to provide
a fork-element system comprising such a fork-element and a gripper drive system with a forkelement and/or a fork-element system.
These objects are solved by the fork-element, the fork-element system, and the gripper drive
system with the features of claims 1, 10 and 15. Preferred embodiments are defined in the
20 dependent claims.
According to a first aspect, a fork-element for a gripper drive system for a weaving machine
comprising a first bearing seat, a second bearing seat, and a main body with a coupling element
configured for coupling the fork-element to a crank of the gripper drive system is provided, wherein
the second bearing seat is positioned closer to the coupling element than the first bearing seat,
25 and wherein the first bearing seat is formed integrally with the main body and the second bearing
seat is formed separately and can be fastened to the main body using fixation elements.
3
Throughout this specification and the following claims, the expressions “first” and “second” are
only used to distinguish one element from another element and not to indicate any order of the
elements.
In a typical use, the fork-element may be arranged such that the first bearing seat is below the
5 second bearing seat, therefore the first bearing seat may also be referred to as lower bearing seat
and the second bearing seat may also be referred to as upper bearing seat.
The coupling element in embodiments is a coupling pin, which in use is rotatably arranged in a
bushing of the crank of the gripper drive system. In other embodiments, the coupling element is
a bushing, which rotatably receives a pin of the crank of the gripper drive system.
10 As the second bearing seat formed separately is positioned closer to the coupling element, the
fixation elements used to fasten the second bearing seat to the main body can be arranged closer
to a centerline of the coupling element about which the fork-element is moved than prior art
fixation elements fastening the first bearing seat to the main body. Therefore, additional mass
balancing elements provided at prior art fork-elements can be reduced or avoided, and an overall
15 weight of the fork-element can be reduced.
In an embodiment, the fixation elements are chosen so that the second bearing seat cannot be
dismantled from the main body.
In other embodiments, the fixation elements are bolts, wherein the main body and the second
bearing seat are each provided with holes for receiving the bolts. In an embodiment, the holes in
20 the second bearing seat are through holes and the holes in the main body are threaded holes,
wherein the bolts are inserted via the through holes in the second bearing seat and threaded into
the threaded holes in the main body. In other embodiment, the holes in the main body are through
holes and the holes in the second bearing seat are threaded holes, wherein the bolts are inserted
via the through holes in the main body and threaded into the threaded holes in the second bearing
25 seat.
In an embodiment, the holes in the main body and in the second bearing seat extend in a direction
perpendicular to a tangent to a bearing ring circle of the second bearing seat at a point of the
bearing ring circle closest to the coupling element.
4
The fork-element is adapted to rotatably support a cross-element in the first bearing seat and the
second bearing seat. In addition, it is known to mount the cross-element to the fork-element such
that it is non-displaceable in axial direction supported in the first bearing seat further away from
the coupling element, which – in use – typically is the lower bearing seat. The expression “non5 displaceable in axial direction supported” is used to describe a structural support, which ideally
prevents a movement in the axial direction, wherein marginal relative movements due to
clearances, resilience and others in embodiments are tolerable. Due to the axial support of the
cross-element, the first bearing seat is subjected to forces in the axial direction. On the other
hand, in case the cross-element is only radially supported in the second bearing seat, the second
10 bearing seat is not subjected to forces in the axial direction. Hence, no cross-forces or shearforces are acting on bolts arranged perpendicular to a direction of a bearing axis defined by the
first bearing seat and the second bearing seat. Therefore, a size and/or a number of bolts can be
reduced compared to prior art devices.
In an embodiment, the second bearing seat can be fastened to the main body using four bolts.
15 In an embodiment, the second bearing seat is fastened to the main body with loose manufacturing
tolerances in the direction of the bearing axis defined by the second bearing seat and the first
bearing seat. In case the cross-element is only radially supported in the second bearing seat, an
arrangement of the second bearing seat in the direction of the bearing axis with respect to the
main body is acceptable with loose manufacturing tolerances.
20 In an embodiment, the main body is a hollow element. This allows for a light-weight design of the
fork-element having sufficient strength. In an embodiment, walls of the hollow main body have
recesses for a further weight reduction.
In an embodiment, a centerline of the coupling element is inclined with respect to a bearing axis
defined by the second bearing seat and the first bearing seat, wherein an inclination angle is less
25 than 90°.
In an embodiment, the centerline of the coupling element intersects the bearing axis defined by
the second bearing seat and the first bearing seat at an intersection point, wherein the intersection
point is closer to the first bearing seat than to the second bearing seat.
In an embodiment, a center of gravity of the fork-element and all elements fixed non-displaceable
30 in position to the fork-element, i.e. all elements moving the same way as the fork-element such
5
as bearing rings fixed to the bearing seats, lies on the centerline of the coupling element. This
allows to avoid imbalance forces when driving the fork-element.
According to a second aspect, a fork-element system comprising the fork-element with the main
body, the first bearing seat and the separate second bearing seat fastened to the main body and
5 comprising a cross-element is provided, wherein the cross-element is rotatably supported in the
second bearing seat of the fork-element and in the first bearing seat of the fork-element, and
wherein the cross-element is non-displaceable in axial direction supported in the first bearing seat
formed integrally with the main body.
As the cross-element is only rotatably supported in the second bearing seat, the second bearing
10 seat is not subjected to bearing forces in a direction of the bearing axis. Hence, fixing elements
used for fastening the second bearing seat to the main body are not subjected to high forces in
the direction of the bearing axis. The direction of the bearing axis is also referred to as axial
direction of the bearings or any elements thereof.
In an embodiment, a first bearing comprising an inner ring and an outer ring, wherein the inner
15 ring is non-displaceable in axial direction with respect to the outer ring, is provided, which first
bearing is arranged between the first bearing seat and the cross-element, wherein the crosselement is non-displaceable in axial direction fixed to the inner ring, in particular via a fixation
plate and bolts, and wherein the outer ring is non-displaceable in axial direction fixed in the first
bearing seat.
20 When fixing the cross-element to the inner ring that is precisely positioned with respect to the first
bearing seat that is formed integrally with the main body, the cross-element can be precisely
positioned with respect to the main body of the fork-element in the axial direction of the bearings,
and thus also with respect to the centerline of the coupling element.
In an embodiment, a distance ring is provided between the inner ring of the first bearing and a
25 shoulder of the cross-element. The distance ring allows a compensation of any height differences
resulting from an arrangement of the bearing in the bearing seat so that the cross-element is
precisely positioned with respect to the main body.
In an embodiment, a first bearing configured to counter axial and radial forces, preferably a
tapered bearing, is arranged between the first bearing seat and the cross-element, and a second
30 bearing configured to counter solely radial forces, preferably a cylinder bearing, is arranged
6
between the second bearing seat and the cross-element. The second bearing allows for a
rotatable support of the cross-element in the second bearing seat. The first bearing allows for a
rotatable and an axial support of the cross-element in the first bearing seat. The first bearing in
embodiments is a tapered bearing, in particular a tapered roller bearing.
5 In embodiments, a gear segment is fixed, in particular bolted, to the cross-element. In use, the
gear segment is rotated back-and-forth about a gear segment axis through the intersection point
of the bearing axis and the centerline. Due to the precise positioning of the cross-element along
the bearing axis, high bearing forces of a shaft of the gear segment can be avoided.
According to a third aspect, a gripper drive system comprising a fork-element and/or a fork10 element system is provided.
BRIEF DESCRIPTION OF THE DRAWINGS
In the following, embodiments of the invention will be described in detail with reference to the
drawings. Throughout the drawings, the same elements will be denoted by the same reference
numerals. The figures show:
15 Fig. 1 shows in a side view a gripper drive system and a rapier drive wheel driven by the
gripper drive system;
Fig. 2 shows in a perspective view the gripper drive system of Fig. 1;
Fig. 3 shows in a perspective view a fork element of the gripper drive system of Fig. 1;
Fig. 4 shows in a sectional side view the fork-element of Fig. 3 and bearings arranged in a
20 first bearing seat and a second bearing seat of the fork-element;
Fig. 5 shows in a sectional top view the fork-element of Fig. 3 and a bearing arranged in the
second bearing seat of the fork-element;
Fig. 6 shows in a sectional side view a fork-element system comprising the fork-element of
Fig. 3, a cross-element, and gear segment fixed to the cross-element; and
25 Fig. 7 shows in a sectional side view a detail of the first bearing seat of Fig. 6.
7
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
Fig. 1 shows a in a side view a gripper drive system 1 that drives a rapier drive wheel 2 to oscillate
back-and-forth upon rotation of a shaft 30 of a weaving machine. Fig. 2 shows in a perspective
view the gripper drive system 1 of Fig. 1.
5 The gripper drive system 1 shown in Figs. 1 and 2 comprises a disk 3 rotating with the shaft 30
of the weaving machine, a crank 4 connected to the disk 3, a fork-element 5 rotatably mounted
on the crank 4, a cross-element 6 rotatably mounted on the fork-element 5 and via bearings 32
in a frame (not shown) of the gripper drive system 1, and a gear segment 7 fixedly connected to
the cross-element 6. The crank 4 also comprises a counterweight 31. Upon rotation of the disk 3,
10 the gear segment 7 is driven to oscillate back-and-forth about a gear segment axis 8. The gear
segment 7 engages a gear 9 connected to the rapier drive wheel 2.
Fig. 3 shows in a perspective view the fork-element 5 of the gripper drive system 1 of Fig. 1, which
fork-element 5 has a first bearing seat 10, a second bearing seat 11, and a main body 12.
Fig. 4 shows in a sectional side view of the fork element 5 together with a first bearing 15 arranged
15 in the first bearing seat 10 and a second bearing 16 arranged in the second bearing seat 11. The
main body 12 of the fork-element 5 has a coupling element 13 configured for coupling the forkelement 5 to the crank 4 of the gripper drive system 1 (see Fig. 1). In use, the fork-element 5 is
moved about a centerline 80 of the coupling element 13. In the embodiment shown, the coupling
element 13 is a coupling pin. However, alternative coupling elements 13 are known to the person
20 skilled in the art.
In the embodiment shown, the main body 12 is a hollow element, wherein walls 71 of the main
body 12 have recesses 70 for a further weight reduction. A size and position of the recesses 70
can be chosen by the person skilled in the art to obtain a main body 12 having a low weight and
a sufficient rigidity.
25 The first bearing 15 and the second bearing 16 are aligned and define a bearing axis 60. The
centerline 80 is inclined with respect to the bearing axis 60 by an inclination angle  (see Fig. 4).
The centerline 80 intersects the bearing axis 60 at an intersection point 86, wherein the
intersection point 86 is closer to the first bearing seat 10 than to the second bearing seat 11.
8
The fork-element 5 has a first arm 54 comprising the first bearing seat 10 and a second arm 55
comprising the second bearing seat 11, wherein the first arm 54 is larger than the second arm 55.
The second bearing seat 11 is positioned closer to the coupling element 13 than the first bearing
seat 10. In the embodiment shown, in use the second bearing seat 11 is arranged above the first
5 bearing seat 10. However, the invention is not limited to this design. The first bearing seat 10 is
formed integrally with the main body 12. The second bearing seat 11 is formed separately and
fastened to the main body 12 using fixation elements 14.
As best seen in Figs. 3, the fixation elements 14 are bolts, for example four bolts arranged at
corners of a square. As best seen in Fig. 5, where only two bolts are shown, for receiving the
10 bolts, the main body 12 is provided with holes 120 and the second bearing seat 11 is provided
with holes 110. In the embodiment shown, the main body 12 is provided with holes 120 in the
form of through holes and the second bearing seat 11 is provided with holes 110 in the form of
threaded holes, wherein the bolts are inserted via the holes 120 in the main body 12 and screwed
into the holes 110 in the second bearing seat 11 for fastening the second bearing seat 11 to the
15 main body 12.
As shown in Fig. 4 the second bearing 16 is fixed to the second bearing seat 11 by a threaded
fixation ring 24. Further a bearing 25 can be provided on the coupling element 13. As shown in
Fig. 4 also a setting pin 26 can be provided to position the second bearing seat 11 with respect
to the main body 12 before the fixation elements 14 are fastened.
20 As shown in Fig. 4, the center of gravity 81 of the fork-element 5 and all elements mounted nondisplaceable in position to the fork-element 5 lies on the centerline 80 of the coupling element 13;
wherein the fork element 5 comprises the main body 12 with the first bearing seat 10, the second
bearing seat 11, the fixation elements 14, the threaded fixation rings 23 and 24, and elements
mounted non-displaceable in position to the fork-element 5, thus, moving in the same way as the
25 fork element 5, such as parts of the bearings 15 and 16. To this end the second bearing seat 11
can also be provided with a small protrusion 28, for example a protrusion made integrally with the
second bearing seat 11.
As shown in Fig. 5, the holes 120 in the main body 12 and the holes 110 in the second bearing
seat 11 each extend in a direction perpendicular to a tangent 51 to a bearing ring circle 52 of the
30 second bearing seat 11 at a point of the bearing ring circle 52 closest to the coupling element 13.
9
As best seen in Fig. 5, the bolts are arranged in parallel to the centerline 80. Further, as the
second arm 55 is smaller in size than the first arm 54, the mass of the second arm 55 including
the fixation elements 14 can be chosen to match the mass of the first arm 54. Therefore, additional
mass balancing elements at the first arm 54 should not be provided, and an overall weight of the
5 fork-element 5 can be reduced.
As further shown in Fig. 4, the first bearing 15 arranged in the first bearing seat 10 is configured
to counter axial and radial forces. In the embodiment shown, the first bearing 15 is a tapered
bearing. The second bearing 16 arranged in the second bearing seat 11 is configured to counter
solely radial forces. In the embodiment shown, the second bearing 16 is a cylinder bearing.
10 Fig. 6 shows in a sectional side view a fork-element system 50 comprising the fork-element 5 and
the cross-element 6 with the gear segment 7. The cross-element 6 is supported via the first
bearing 15 in the first bearing seat 10 and via the second bearing 16 in the second bearing seat
11, and the gear segment 7 fixed to the cross-element 6. The gear segment 7 is mounted to the
cross-element 6 using several bolts 27. Setting pins 29 can be provided to position the gear
15 segment 7 with respect to the cross-element 6 before the bolts 27 are fastened.
As best seen in Fig. 6, the first bearing 15 configured to counter axial and radial forces defines
an axial position of the cross-element 6, i.e. a position of the cross-element 6 with respect to forkelement 5 along a bearing axis 60 as well as a radial position of the cross-element 6 at the first
bearing 15, while the second bearing 16 solely defines the radial position of the cross-element 6
20 at the second bearing 16 with respect to the bearing axis 60.
Due to the design of the second bearing 16, the second bearing 16 does not counter forces in the
axial direction, i.e., in the direction along or in parallel to the bearing axis 60. Therefore, no forces
or only small forces are exerted on the second bearing seat 11 in the axial direction defined by
the bearing axis 60. Hence, the fixation elements 14 fastening the second bearing seat 11 to the
25 main body 12 are not subjected to high shear forces in the axial direction defined by the bearing
axis 60.
Further, as the axial position of the cross-element 6 is determined by means of the first bearing
15 formed integrally with the main body 12, a small relative shifting of the second bearing seat 11
with respect to the cross-element 6 in the axial direction defined by the bearing axis 60 is tolerable.
30 Hence, for fixing the second bearing seat 11 to the main body 12 using the bolts, a limited shifting
is tolerable. On the other hand, the second bearing seat 11 and the main body 12 contact each
10
other at an abutment surface 53, where a planar surface of the second bearing seat 11 and a
planar surface of the main body 12 are pressed against each other, which abutment surface 53
extends in parallel to the bearing axis 60 and to the tangent 51 (see Fig. 5). The planar surface
of the second bearing seat 11 and the planar surface of the main body 12 can be machined
5 precisely parallel to the tangent 51 and cross to the tangent 51, so that the abutment surface 53
will be arranged in parallel with the bearing axis 60. If the fixation elements 14 have play inside
the holes 120, the second bearing 16 can be positioned precisely with respect to the tangent 51,
so that the bearing axis 60 coincides with the axial direction of the cross-element 6.
As the axial position along the bearing axis 60 of the cross-element 6 is determined by means of
10 the first bearing 15 formed integrally with the main body 12, the axial position of the cross-element
6 can be precisely set with respect to the coupling element 13 of the main body 12.
In the embodiment shown, as best seen in Fig. 7, which shows a detail of Fig. 6, the first bearing
15 comprises two inner rings 17 and two outer rings 18, which outer rings 18 are separated by a
distance ring 22, wherein the inner rings 17 are non-displaceable in the axial direction supported
15 in the outer rings 18. The outer rings 18 are arranged fixed in position in the first bearing seat 10,
and the outer rings 18 are fixed by a threaded fixation ring 23 between a base surface 63 of the
first bearing seat 10 and the fixation ring 23. The inner ring 17 is fixed to the cross-element 6
using a fixation plate 20 and bolts 21, so that the cross-element 6 is not displaceable in the axial
direction defined by the bearing axis 60 with respect to the inner rings 17, and thus with respect
20 to the outer rings 18, and thus with respect to the main body 12. In the embodiment shown, the
fixation plate 20 is circular or ring-shaped, wherein the fixation plate 20 has holes via which the
bolts 21 are for example inserted into threaded holes of the cross-element 6. The fixation plate
20 contacts an outer end of the inner ring 17, and by tightening the bolts 21, the fixation plate 20
forces the inner ring 17 towards a side end 61 of the cross-element 6. A distance ring 19 is
25 provided between an inner end of the inner ring 17 of the first bearing 15 and a shoulder 62 of the
cross-element 6. A height of the distance ring 19 can be chosen so that the position of the
shoulder 62 is arranged in a defined desired axial position with respect to the first bearing seat
10, and in this way the cross-element 6 is arranged in a defined desired axial position with respect
to the main body 12.
30
11
We Claim
1. A fork-element for a gripper drive system (1) for a weaving machine comprising a first
bearing seat (10), a second bearing seat (11), and a main body (12) with a coupling
element (13) configured for coupling the fork-element (5) to a crank (4) of the gripper drive
system (1), wherein the second bearing seat (11) is positioned closer to the coupling
element (13) than the first bearing seat (10), characterized in that the first bearing seat
(10) is formed integrally with the main body (12) and the second bearing seat (11) is
formed separately and can be fastened to the main body (12) using fixation elements (14).
2. The fork-element according to claim 1, characterized in that the fixation elements (14) are
bolts, wherein the main body (12) and the second bearing seat (11) are each provided
with holes (120, 110) for receiving the bolts.
3. The fork-element according to claim 2, characterized in that the holes (120, 110) extend
in a direction perpendicular to a tangent (51) to a bearing ring circle (52) of the second
bearing seat (11) at a point of the bearing ring circle (52) closest to the coupling element
(13).
4. The fork-element according to claim 2 or 3, characterized in that the second bearing seat
(11) can be fastened to the main body (12) using fixation elements (14), in particular four
bolts.
5. The fork-element according to any one of claims 1 to 4, characterized in that the second
bearing seat (11) is fastened to the main body (12) with loose manufacturing tolerances
in a direction of a bearing axis (60) defined by the second bearing seat (11) and the first
bearing seat (10).
6. The fork-element according to any one of claims 1 to 5, characterized in that the main
body (12) is a hollow element, wherein in particular walls (71) of the main body (12) have
recesses (70) for a weight reduction.
7. The fork-element according to any one of claims 1 to 6, characterized in that a centerline
(80) of the coupling element (13) is inclined with respect to a bearing axis (60) defined by
12
the second bearing seat (11) and the first bearing seat (10), wherein an inclination angle
() is less than 90°.
8. The fork-element according to claim 7, characterized in that a centerline (80) of the
coupling element (13) intersects the bearing axis (60) defined by the second bearing seat
(11) and the first bearing seat (10) at an intersection point (86), wherein the intersection
point (86) is closer to the first bearing seat (10) than to the second bearing seat (11).
9. The fork-element according to any one of claims 1 to 8, characterized in that a center of
gravity (81) of the fork-element (5) and all elements fixed non-displaceable in position to
the fork-element (5) lies on the centerline (80) of the coupling element (13).
10. A fork-element system comprising the fork-element (5) according to any one of claims 1
to 9 and a cross-element (6), wherein the cross-element (6) is rotatably supported in the
second bearing seat (11) of the fork-element (5) and in the first bearing seat (10) of the
fork-element (5), characterized in that the cross-element (6) is non-displaceable in axial
direction supported in the first bearing seat (10) formed integrally with the main body (12).
11. The fork-element system according to claim 10, characterized in that a first bearing (15)
comprising an inner ring (17) and an outer ring (18), wherein the inner ring (17) is nondisplaceable in axial direction with respect to the outer ring (18), which first bearing (15) is
arranged between the first bearing seat (10) and the cross-element (6), wherein the crosselement (6) is non-displaceable in axial direction fixed to the inner ring (17), in particular
via a fixation plate (20) and bolts (21), and wherein the outer ring (18) is non-displaceable
in axial direction fixed to the first bearing seat (10).
12. The fork-element system according to claim 11, characterized in that a distance ring (19)
is provided between the inner ring (17) of the first bearing (15) and a shoulder (62) of the
cross-element (6).
13. The fork-element system according to claim 10, 11 or 12, characterized in that a first
bearing (15) configured to counter axial and radial forces, preferably a tapered bearing, is
arranged between the first bearing seat (10) and the cross-element (6), and wherein a
13
second bearing (16) configured to counter solely radial forces, preferably a cylinder
bearing, is arranged between the second bearing seat (11) and the cross-element (6).
14. The fork-element system according to any one of claims 10 to 13, characterized in that a
gear segment (7) is fixed to the cross-element (6).
15. A gripper drive system for a weaving machine comprising a fork-element (5) according to
any one of claims 1 to 9 and/or a fork-element system (50) according to any one of claims
10 to 14.
Dated this 10th day of April 2025

(Dr. Sudipta Banerjee)
5 Patent Agent (Regd. No.: IN/PA-210)
of P.S. Davar and Company
Applicant’s Agent
14