EP3478882A1

EP3478882A1 - Device for clamping weft threads

Info

Publication number: EP3478882A1
Application number: EP17728879.2A
Authority: EP
Inventors: Eddy Verclyte; Wim Hoorelbeke; Ronny COULEMBIER
Original assignee: Picanol NV
Current assignee: Picanol NV
Priority date: 2016-07-04
Filing date: 2017-06-12
Publication date: 2019-05-08
Anticipated expiration: 2037-06-12
Also published as: CN109415849A; BE1024401A1; BE1024401B1; WO2018007104A1; EP3478882B1; CN109415849B

Abstract

The invention relates to a device and amethod for clamping weft threads in a weaving machine, the device comprising at least one clamping unit (20, 21), a support element (16), and an opener element (40) with at least one finger (41, 42, 43), wherein the support element (16) and the opener element (40) are mounted displaceable relative to each other in a clamping direction (14), wherein each clamping element (22, 23, 24, 25) is pivotally mounted to the support element (16) about a pivot axis (17, 18) perpendicular to the clamping direction (14), and in that the opener element (40) is adapted to be arranged in an operating position, wherein when the opener element (40) is arranged in the operating position, upon a relative displacement between the support element (16) and the opener element (40) the at least one finger (41, 42, 43) interacts with one of the clamping elements (22, 23, 24, 25) for causing said clamping element (22, 23, 24, 25) to pivot about the pivot axis (17, 18) against the force of the at least one force element (28, 29) for opening an associated clamp (60, 61, 62, 63).

Description

Device for clamping weft threads

TECHNICAL FI ELD AND PRIOR ART

[0001 ] The invention relates to a device and a method for clamping weft threads in a weaving machine, more particularly in a rapier weaving machine. [0002] In rapier weaving machines, also named gripper weaving machines, a weft thread positioned in the path of a gripper is gripped by the gripper and inserted into a shed. The inserted weft thread is cut off on the insertion side in order to allow a subsequent weft thread to be inserted. It is known to position a weft thread to be inserted in the path of the gripper by using a presenting element of a presenting device that is arranged on the weaving machine next to the shed, for example as described in EP 0 598 264 A1 .

[0003] It is known to provide a clamping device arranged between a presenting device and a weft thread cutter. For example US 5,492, 153, EP 0 421 349 A1 and WO 2013007551 A2 describe clamping devices with a number of clamping elements. One of the clamping elements is connected to a drive element, while the other clamping elements are forced by means of spring elements towards the clamping element that is connected to the drive element.

[0004] In US 5,492, 153 a device comprising a plurality of clamping elements is described, wherein two adjacent clamping elements define a clamp. The central clamping element is fixedly mounted to a rod and moveable by means of the rod in the clamping direction. The other clamping elements are forced by springs towards the central clamping element. The device further comprises an opener element in order to move two adjacent clamping elements apart in order to allow a weft thread to enter between these two adjacent clamping elements. By means of the rod, two selected clamping elements can be moved in front of the opener element.

[0005] The device for clamping a weft thread according to WO 2013007551 A2 is adapted to co-operate with two weft threads. Several such devices for clamping a weft thread can be provided which allows weaving with more than two weft threads. For example two such devices can be used which are arranged mirror symmetrical to each other. Nevertheless using a number of such devices does not result in a compact structure to be arranged on a weaving machine. SUMMARY OF THE I NVENTION

[0006] It is an object of the invention to provide a device and a method for clamping weft threads that allow a reliable clamping and releasing of weft threads regardless of their thickness. [0007] This object is solved by a device for clamping weft threads with the features of claim 1 , a weaving machine with the features of claim 14 and a method with the features of claim 15. Further advantages are described in the dependent claims.

[0008] According to a first aspect a device for clamping a plurality of weft threads is provided, the device comprising at least one clamping unit, a support element, and an opener element with at least one finger, wherein the at least one clamping unit comprises an abutment element fixedly attached to the support element, at least one clamping element moveably mounted to the support element and arranged at a side of the abutment element, in particular two clamping elements moveably mounted to the support element at either side of the abutment element, and at least one force element, wherein each clamping element together with the abutment element defines a clamp, wherein the at least one force element forces each clamping element towards the abutment element, wherein the support element and the opener element are mounted displaceable relative to each other in a clamping direction, wherein each clamping element is pivotally mounted to the support element about a pivot axis perpendicular to the clamping direction, and wherein the opener element is adapted to be arranged in an operating position, wherein when the opener element is arranged in the operating position, upon a relative displacement between the support element and the opener element the at least one finger interacts with one of the clamping elements for causing said clamping element to pivot about the pivot axis against the force of the at least one force element for opening the associated clamp. [0009] This allows each weft thread to be clamped in an associated clamp in a reliable way and independent of the thickness of each of the weft threads.

[0010] In preferred embodiments, the device comprises at least two clamping elements associated to one clamping unit or to different clamping units. In one embodiment, only one clamping unit is provided, wherein the one clamping unit comprises two clamping elements moveably mounted to the support element at either side of the abutment element. In other embodiments, two or more clamping units are provided, wherein each clamping unit comprises only one clamping element or two clamping elements moveably mounted to the support element at either side of the abutment element.

[001 1 ] The abutment element is fixedly arranged at the support element. In one embodiment, the abutment element is manufactured integrally with the support element. In other embodiments, the abutment element is manufactured separately and attached fixed in position to the support element. The clamping elements are pivotally mounted to the support element and a clamp is opened by pivoting the associated clamping element against the force of the at least one associated force element away from the abutment element. The clamping element in preferred embodiments is a two-sided lever, wherein a front end contacts the abutment element for forming a clamp and wherein the rear end is forced by means of the force element for forcing the front end towards the abutment element. The force element is for example a spring mounted between the abutment element and the clamping element or mounted between the two clamping elements of one clamping unit.

[0012] A pivot movement of one clamping element for opening the respective clamp is caused by an interaction between the opener element, more particular a finger of the opener element, and said clamping element upon the relative movement of the opener element and the support element in the clamping direction. In one embodiment, the opener element is mounted moveable in the clamping direction for causing a pivot movement of the clamping element. In preferred embodiments, the opener element is held fixed in position in the clamping direction for allowing moving the clamping element away from the abutment element by a movement of the support element. In one embodiment, the finger is fork-shaped having two teeth, wherein each tooth can interact with one clamping element of a clamping unit. In preferred embodiments, a bar-shaped or spear-shaped finger is provided which is arranged to interact with the clamping elements. [0013] In one embodiment, each clamping element is provided with an operating structure displaced from the pivot axis for interacting with the at least one finger of the opener element upon a relative displacement between the support element and the opener element. In one embodiment, the operating structure is provided on a surface of the respective clamping element perpendicular to the clamping direction. [0014] In preferred embodiments, the operating structure is an operating pin protruding from a side surface of the respective clamping element, wherein in particular the operating pin is arranged between the pivot axis of the clamping element and a clamping position for a weft thread. When providing an operating pin between the clamping position and the pivot axis in a direction perpendicular to the clamping direction, one finger, which is inserted between the two operating pins of one clamping unit is sufficient for a selective operation of both clamps associated with an abutment element, wherein one of the two clamping elements is forced to pivot about its pivot axis depending on the movement direction of the operating structure relative to the opener element in the clamping direction. In embodiments, as opener element a single bar-shaped finger is provided that is arranged fixed in position in the clamping direction. In other embodiments, an opener element with fork-shaped fingers is provided, wherein each finger can be assigned to at least one clamping element of a clamping unit.

[0015] It will be apparent to the person skilled in the art, that when providing only one clamping unit the opener element can be mounted fixed in position, wherein the clamping unit is moved to-and-fro in the clamping direction for opening one of the two associated clamps. In preferred embodiments two or more clamping units are provided, wherein the opener element is mounted displaceable between the operating position and a rest position in a feed direction perpendicular to the clamping direction at a fixed height in the clamping direction, and wherein the support element is mounted displaceable in the clamping direction, so that when the opener element is in the rest position by displacing the support element in the clamping direction a selected clamping unit can be placed in front of the central finger of the opener element. In other words, the opener element is moveable into the rest position for displacing the support element together with the clamping elements, wherein all clamps remain closed. After a selected clamping unit is placed in front of a finger, the finger is moved into the operating position and a displacement of the support element causes a pivot movement of one of the clamping elements as described above.

[0016] In preferred embodiments, exactly two clamping units are provided, wherein the opener element comprises one central finger and two outer fingers, wherein the two outer fingers are displaced from the central finger in the feed direction, wherein the opener element is moveable in the feed direction between a rest position, a first operating position and a second operating position, wherein the opener element when arranged in the first operating position or in the second operating position interacts with the clamping elements upon a relative displacement between the support element and the opener element in the clamping direction, so that one of the central finger and the two outer fingers interacts with one of the clamping elements for causing said clamping element to pivot about the pivot axis against the force of the at least one force element for opening the associated clamp or for reducing a clamping force at the associated clamp. This allows opening a clamp when the respective clamping unit is not placed in front of the central finger. For example, when arranging a first clamp provided at a first clamping unit in front of the central finger for receiving an inserted weft thread, after receiving the weft thread and closing the first clamp the opener element can be moved into the second operating position and by displacing the support element relative to the opener element in the clamping direction a second clamp provided at a second clamping unit, which is not arranged in front of the central finger, can be opened, or a clamping force at this clamp can be reduced, by means of one of the outer fingers.

[0017] In order to avoid any unnecessary motion between the opener element and the support element, in preferred embodiments, the two outer fingers are provided at either side of the central finger in the clamping direction and displaced from the central finger in the clamping direction, wherein a distance between the central finger and each outer finger at least essentially equals to a distance between the abutment elements of the two clamping units. In other words, when placing the central finger in front of one clamping unit, one outer finger is placed in front of the other clamping unit.

[0018] The opener element in preferred embodiments is formed such that the central finger does not interfere with clamping elements upon a relative displacement between the support element and the opener element in the clamping direction, when the opener element is in the second operating position.

[0019] In preferred embodiments, a first driving device comprising a first motor is provided for a displacement of the support element in the clamping direction, wherein in particular the first driving device comprises a first eccentric driven to pivot about a first drive axis perpendicular to the clamping direction. The eccentric allows positioning the support element together with the clamping units very accurately. Such a driving device is not subjected to wear and not sensitive to vibrations.

[0020] In one embodiment, the eccentric is in contact with the support element and directly drives the support element. In preferred embodiments, the first driving device further comprises a first transfer element mounted slidably, wherein the first eccentric drives the first transfer element to move the first transfer element to-and-fro in the clamping direction upon rotation of the first eccentric. The design of the transfer element is chosen suitably by the person skilled in the art. In preferred embodiments, the first transfer element is a first frame, wherein the first eccentric is arranged inside the first frame. The stroke of the transfer element depends among others on dimensions of the frame, a size of the eccentric, a relative position of the drive axis of the eccentric with respect to the center of the frame and/or a relative angular rotation of the drive axis. The opposing surfaces of the eccentric and the frame in one embodiment are made of or coated with a wear-resistant material. In preferred embodiments, a wear protection ring is provided between the first eccentric and the first frame to limit the wear.

[0021 ] In preferred embodiments, a second driving device comprising a second motor is provided for a displacement of the opener element in the feed direction. The second driving device in preferred embodiments has at least essentially a similar design as the first driving device to decrease the manufacturing costs.

[0022] In particular, in preferred embodiments, the second driving device comprises a second eccentric driven to pivot about a second drive axis perpendicular to the feed direction. The second driving device further in preferred embodiments comprises a second transfer element mounted slidably, wherein the second eccentric drives the second transfer element to move the second transfer element to-and-fro in the feed direction upon rotation of the second eccentric. The second transfer element in particular can be a second frame, wherein the second eccentric is arranged inside the second frame, and wherein in particular a wear protection ring can be provided between the second eccentric and the second frame. [0023] According to a second aspect, a weaving machine with a device for clamping weft threads is provided. In preferred embodiments the device is arranged at an angle with respect to an insertion direction of the weaving machine, so that a weft thread entering into the device extends at least essentially perpendicular to the direction in which the weft thread enters into the device. [0024] According to a third aspect, a method for clamping weft threads with a device comprising at least one clamping unit, a support element, and an opener element with at least one finger is provided, wherein the clamping unit comprises an abutment element fixedly mounted to the support element, at least one clamping element moveably mounted to the support element and arranged at a side of the abutment element, in particular two clamping elements moveably mounted to the support element at either side of the abutment element, and at least one force element, wherein each clamping element together with the abutment element defines a clamp, wherein the at least one force element forces the clamping elements towards the abutment element, and wherein each clamping element is pivotally mounted to the support element about a pivot axis perpendicular to a clamping direction, the method comprises displacing the support element relative to the opener element in a clamping direction while the opener element is arranged in an operating position, wherein the at least one finger interacts with one of the clamping elements for causing said clamping element to pivot about the pivot axis against the force of the at least one force element for opening the associated clamp. BRI EF DESCRIPTION OF THE DRAWINGS

[0025] In the following, an embodiment 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. Fig. 1 is a top view of the device for clamping a weft thread arranged on a rapier weaving machine;

Fig. 2 is a perspective view of a device for clamping a weft thread of Fig. 1 ; Fig. 3 is a side view seen in the direction of arrow S of Fig. 1 in a first state; is the side view of Fig. 3 in a second state; is the side view of Fig. 3 in a third state; is the side view of Fig. 3 in a fourth state;

Fig. 7 is an enlarged perspective view of a part of Fig. 3 in a fifth state;

Fig. 8 is a dismantled view of the device for clamping a weft thread of Fig. 1 ; and

Fig. 9 is a dismantled view of a support element and two clamping units of the device of

Fig. 8. is a perspective view of a device for clamping a weft thread of Fig. 1 . DETAI LED DESCRI PTION OF EMBODIMENTS OF THE I NVENTION

[0026] Fig. 1 shows a top view of a device 1 for clamping weft threads, arranged on a rapier weaving machine. The rapier weaving machine is only partly shown. The rapier weaving machine comprises presenting devices 2 for presenting weft threads 7, 8, 9, 10, and a gripper 3 for gripping one or more weft threads 7, 8, 9, 10 presented by presenting devices 2 and for inserting presented weft threads into a shed. The rapier weaving machine further comprises a thread guiding device 4 and a cutting apparatus 5. As can be seen in Fig. 2, the device 1 for clamping weft threads is arranged between the cutting apparatus 5 and the thread guiding device 4. The cutting apparatus 5 is attached to a support 6 that supports the device 1 for clamping weft threads.

[0027] In Fig. 1 , four weft threads 7, 8, 9, 10 are schematically shown. The device 1 is arranged for receiving a weft thread 7, 8, 9, 10 upon beat up and to retain a plurality of weft threads 7, 8, 9, 10 after the weft threads are cut by means of the cutting apparatus 5. After an insertion of one of the weft threads, for example an insertion of the second weft thread 8, the second weft thread 8 guided past the thread guiding device 4 runs from the presenting device 2, via the device 1 for clamping weft threads and the cutting apparatus 5 to the cloth edge 1 1 and the woven cloth 12 with the cloth line 13. As indicated in Fig. 1 the cloth edge 1 1 is a side edge of the cloth 12 that extends in warp direction, while the cloth line 13 is the beat up edge of the cloth 12 that extends in weft direction. After clamping the weft thread 8 by means of the device 1 , the clamped weft thread 8 is cut off by the cutting apparatus 5 between the device 1 and the cloth edge 1 1 . During a subsequent insertion, one of the weft threads 7, 8, 9, 10 presented by one of the presenting devices 2 is taken up by the gripper 3, the leading end of the weft thread is pulled out of the device 1 and the weft thread is inserted in the shed. After the insertion, the inserted weft thread is moved upon beat-up to enter an associated clamp of the device 1 .

[0028] As best seen in Fig. 1 , in the embodiments shown the cutting apparatus 5 forms a functional unit or module with the device 1 for clamping weft threads. This module can be positioned with respect to a frame of the weaving machine, in particular in an adjustable position with respect to a gripper path, a cloth line and a cloth edge, and fixedly mounted to the frame of the weaving machine in a suitable position.

[0029] In Fig. 1 , the device 1 is arranged at an angle with respect to the insertion direction N, wherein the angle is adapted to the line of a weft thread 8 running from the presenting device 2 to the cloth edge 1 1 , so that clamping elements of the device 1 (not shown in detail in Fig. 1 ) extend in a direction at least essentially perpendicular to the direction in which weft threads enter the device 1 . Such an arrangement is advantageous for catching the weft thread.

[0030] Fig. 2 shows a perspective view of an embodiment of the device 1 according to the invention and the arrangement of this device 1 with respect to a cutting apparatus 5 and a thread guiding device 4. Figs. 3 to 7 show side views of the device 1 of Fig. 2 seen in the direction of arrow S in Fig. 1 in five different states of use. Fig. 8 is an exploded view of the device 1 of Fig. 2. Fig. 9 is a dismantled view of a support element 16 and two clamping units 20, 21 of the device 1 of Fig. 2. Fig. 10 shows another perspective view of an embodiment of the device 1 according to the invention. [0031 ] In the embodiment shown in Figs. 2 to 10, the device 1 for clamping weft threads comprises a support element 16 and two clamping units 20, 21 , which are arranged at the support element 16 one above the other in a clamping direction 14.

[0032] As best seen in Figs. 7 and 9, each clamping unit 20, 21 comprises two clamping elements 22, 23, 24, 25, an abutment element 26, 27 arranged between the two clamping elements 22, 23, 24, 25 and a force element 28, 29. The force element 28, 29 is a spring in the embodiment shown. The abutment elements 26, 27 are arranged fixedly in position at the support element 16. In the embodiment shown, the abutment elements 26, 27 are manufactured integrally with the support element 16. Each clamping element 22, 23, 24, 25 together with the associated abutment element 26, 27 defines a clamp 60, 61 , 62, 63 that can clamp a weft thread in a clamping position between a clamping element 22, 23, 24, 25 and an associated abutment element 26, 27. In the embodiment shown, the clamping device 1 has four clamps 60, 61 , 62, 63, each for clamping one of the four weft threads 7, 8, 9, 10 (see Fig. 1 ). For receiving a weft thread 7, 8, 9, 10 in a clamp or for releasing a clamped weft thread 7, 8, 9, 10, each clamping element 22, 23, 24, 25 is pivotally mounted to the support element 16 about a pivot axis 17, 18 perpendicular to the clamping direction 14, which pivot axis 17, 18 is mounted to the support element 16. The clamping elements 22, 23, 24, 25 each take the form of a two-sided lever, wherein at each clamping unit 20, 21 the force element 28, 29 is arranged between the rear ends of the two clamping elements 22, 23, 24, 25, and wherein the force element 28, 29 forces the respective front ends of the two clamping elements 22, 23, 24, 25 against the abutment elements 26, 27. The clamping elements 22, 23, 24, 25 are suitably formed for ensuring a good clamping in a particular zone of the clamping elements 22, 23, 24, 25. In the embodiment shown, as best seen in Fig. 9, the abutment elements 26, 27 are provided with clamping surfaces having a T-shaped cross-section facing the clamping elements 22, 23, 24, 25 having clamping surfaces with a corresponding U-shaped cross-section. For opening a clamping position, the associated clamping element 22, 23, 24, 25 is pivoted about the pivot axis 17, 18 against the force of the force element 28, 29. For applying an operation force or motion for causing a pivot movement of the clamping elements 22, 23, 24, 25 about the pivot axes 17, 18, the clamping elements 22, 23, 24, 25 are provided with operating pins 44, 45, 46, 47 protruding from a side surface of the clamping elements 22, 23, 24, 25. In the embodiment shown, each operating pin 44, 45, 46, 47 is arranged in the feed direction 15 between the pivot axis 17, 18 and the clamping position of the associated clamping element 22, 23, 24, 25. Hence, forces applied to the operating pins 44, 45, 46, 47 pointing away from the abutment elements 26, 27 will cause a pivot movement of the clamping elements 22, 23, 24, 25 for opening the clamp. [0033] The operation of the device is explained with reference to Figs. 3 to 7. For the operation, the device 1 comprises an opener element 40. The support element 16 together with the clamping units 20, 21 is displaceable relative to the opener element 40 in the clamping direction 14 by means of a first driving device 30. In the embodiment shown, the clamping direction 14 is oriented essentially vertical. However, this orientation is not necessary for the functioning of the device and other orientations are conceivable. Further, the opener element 40 is arranged displaceable in a feed direction 15 perpendicular to the clamping direction 14 at a fixed height in the clamping direction 14 between a rest position, a first operating position and a second operating position. A movement of the opener element 40 is effected by means of a second driving device 50.

[0034] A pivot movement of the clamping elements 22, 23, 24, 25 for opening a clamp 60, 61 , 62, 63 is effected by means of the opener element 40. In the embodiment shown, the opener element 40 has a central finger 41 protruding in the feed direction 15, that in a first operating position can interact with operating pins 44, 45, 46, 47 protruding from side surfaces of the clamping elements 22, 23, 24, 25.

[0035] In the state shown in Fig. 3, the opener element 40 is moved to the rest position away from the support element 16. When the opener element 40 is in the rest position as shown in Fig. 3, the support element 16 can be moved to-and-fro in the clamping direction 14 by means of the first driving device 30, wherein all clamping positions remain securely closed due to the forces applied by the force elements 28, 29 . For opening a clamping position of the upper clamping unit 20, the support element 16 is moved such that the associated clamping unit 20 is placed in front of the central finger 41 of the opener element 40. Next, the opener element 40 is driven to move in the feed direction 15 into a first operating position.

[0036] In the embodiment shown, in the first operating position the opener element 40 is moved towards the clamping unit 20 so that the central finger 41 enters between the two operating pins 44, 45 of the two clamping elements 22, 23 of the clamping unit 20 placed in front of the central finger 41 as shown in Fig. 4. The support element 16 is then driven to move upwards or downwards in the clamping direction 14.

[0037] When moving the support element 16 upwards as shown in Fig. 5, the central finger 41 interacts with the operating pin 45 of the lower clamping element 23 of the two clamping elements 22, 23. Hence, a conjoint movement of the operating pin 45 together with the support element 16 in the clamping direction 14 is hindered by the central finger 41 . The clamping element 23 is mounted to the support element 16 pivotally about the pivot axis 18, which pivot axis 18 is arranged at and moved with the support element 16. By a movement of the support element 16 with respect to the central finger 41 , a pivot movement of this clamping element 23 about the pivot axis 18 is caused. Similar, when moving the support element 16 downwards from the state as shown in Fig. 4, the central finger 41 interacts with the operating pin 44 of the upper clamping element 22 of the two clamping elements 22, 23 causing a pivot movement of this clamping element 22 about the pivot axis 17, which pivot axis 17 is arranged at the support element 16 and moved with the support element 16.

[0038] The central finger 41 is arranged fixed in position in the clamping direction 14, wherein the position of the central finger 41 is adapted to the position and the design of the thread guiding device 4 allowing a good guidance of an inserted weft thread into the clamp 60, 61 , 62, 63 towards the clamping position. As shown in Fig. 5, preferably the support element 16 is moved for opening a clamp 61 such that the abutment element 26 and the clamping element 23 are at least essentially aligned with a guiding element 64, 65, 66 of the thread guiding device 4. Hereby, the inserted weft thread is guided by guiding elements 64, 65, 66 of the thread guiding device 4 to the associated clamp 61 that is arranged almost aligned with the guiding elements 64, 65, 66. The guiding element 66 is arranged in a settable angular position to the thread guiding device 4 in order to set the split between the guide elements 65 and 66 near the clamps.

[0039] In order to release clamped weft threads for an insertion, the respective clamp can be opened by means of the central finger 41 as described above. In the embodiment shown, the opener element 40 is provided with two additional outer fingers 42, 43 at either side of the central finger 41 . The outer fingers 42, 43 are displaced from the central finger 41 in the clamping direction 14, wherein the distance between the outer fingers 42, 43 and the central finger 41 is chosen so that when one clamping unit 20, 21 is arranged in front of the central finger 41 , one of the outer fingers 42, 43 can enter between the operating pins 44, 45, 46, 47 of the other clamping unit 20, 21 , this means the outer finger 42 is intended to interact with the operating pin 44 or 45, the outer finger 43 is intended to interact with the operating pin 46 or 47 and the central finger 41 is intended to interact with the operating pin 44, 45, 46 or 47. In the state shown in Fig. 4, the upper clamping unit 20 is positioned in front of the central finger 41 for receiving a weft thread in one of its clamps. From the rest position shown in Fig. 3, the opener element 40 can move beyond the first operating position shown in Figs. 4 and 5 towards a second operating position shown in Fig. 6. For moving the opener element 40 into the second operating position, the opener element 40 is moved beyond the first operating position towards the second operating position such that a distal end of the central finger 41 is moved beyond the operating pins 44, 45 of the upper clamping unit 20, and the lower outer finger 43 is moved between the operating pins 46, 47 of the lower clamping unit 21 .

[0040] As shown in Fig. 6, when moving the support element 16 upwards while the lower outer finger 43 is arranged between the operating pins 46, 47 of the lower clamping unit 21 as shown in Fig. 6, the lower clamping element 24 is pivoted about its pivot axis 18. Depending of the stroke of the support element 16, the clamp is fully opened, or only partly opened such that a clamping force acting on a clamped weft thread (not shown) is lowered.

[0041 ] In the embodiment shown, the outer fingers 42, 43 are displaced from the central finger 41 in the feed direction 15 such that the outer fingers 42, 43 are not in the movement path of the operating pins 44, 45, 46, 47 when the opener element 40 is in the first operating position (see Figs. 4, 5) and the central finger 41 is positioned between the operating pins 44, 45, 46, 47. Further, the central finger 41 is formed such that an interference or collision of the central finger 41 and the operating pins 44, 45, 46, 47 is avoided when the opener element 40 is in the second operating position (see Fig. 6) and one of the outer fingers 42, 43 is positioned between the operating pins 44, 45, 46, 47. For example, the central finger 41 is provided with a protrusion 49 (see Fig. 7) at its distal end that only in the first operating position can interact with the operating pins 44, 45, 46, 47.

[0042] Preferably, when the opener element 40 is in the second operating position (see Fig. 6), the support element 16 is displaced only over a small distance. For fully opening the lower clamp 63, the opener element 40 is moved back into the rest position (see Fig. 3) and the support element 16 is moved together with the clamping units 20, 21 in the clamping direction 14 for bringing the second clamping unit 21 in front of the central finger 41 , so that upon moving the opener element 40 into the first operating position the protrusion 49 of the central finger 41 enters between the operating pins 46, 47 of the lower clamping unit 21 as shown in Fig. 7. [0043] As best seen in Fig. 8, a first driving device 30 is provided comprising a first eccentric 31 driven to pivot about a first drive axis 32, which first drive axis 32 is perpendicular to the clamping direction 14, for displacing the support element 16 in the clamping direction. The first driving device 30 further comprises a first transfer element 33 in the form of a first frame, wherein the support element 16 is fixedly mounted to the first frame. In the embodiment shown, the support element 16 is fixedly mounted to the first frame by screws 19. Optionally, pins 67 are provided for positioning the support element 16. The first eccentric 31 is arranged inside the first frame. The first frame drives the first eccentric 31 to move in the clamping direction 14 upon rotation of the eccentric 31 . For limiting the wear, due to forces on opposing parts, between the first eccentric 31 and the first frame, in the embodiment shown a wear protection ring 34 is provided at the periphery of the eccentric 31 between the eccentric 31 and the first frame.

[0044] The first driving device 30 further comprises a first motor 35 having a motor axis 36. The eccentric 31 is mounted to the motor axis 36 by means of a mounting element 37 formed integrally with the eccentric 31 and a fixation element 38 screwed to the mounting element 37 using screws 39.

[0045] The movement of the support element 16 is transferred to the clamping elements 22, 23,

24, 25 and all clamping elements 22, 23, 24, 25 are displaced together with the support element 16. In case the opener element 40 is in its rest position as shown in Fig. 3, during this movement, apart from neglectable movements due to inertia and other effects, the clamping elements 22, 23, 24, 25 maintain their relative position with respect to the abutment elements 26, 27 due to the force of the force elements 28, 29 acting on the clamping elements 22, 23, 24,

25. Further, the movement of the support element 16 does not cause a compression or deformation of the force elements 28, 29. Hence, the clamping force remains at least essentially constant independent of the position of the support element 16 in the clamping direction 14.

[0046] The opener element 40 can be driven by means of a second driving device 50 to move in the feed direction 15 and to enter between the operating pins 44, 45, 46, 47 of two clamping elements 22, 23, 24, 25.

[0047] In the embodiment shown, the second driving device 50 adapted for displacing the opener element 40 is similar in construction to the first driving device 30. The second driving device 50 comprises a second eccentric 51 driven to pivot about a second drive axis 52, which second drive axis 52 is perpendicular to the feed direction 15. The second driving device 50 further comprises a second transfer element 53 in the form of a second frame, wherein the opener element 40 is mounted fixedly to the second frame using screws 48 and pins 68. The second eccentric 51 is arranged inside the second frame, wherein in the embodiment shown a wear protection ring 54 is provided at the periphery of the second eccentric 51 between the second eccentric 51 and the second frame. The second eccentric 51 acts on the second frame to move the second frame in the feed direction 15 upon rotation of the second eccentric 51 . The second driving device 50 further comprises a second motor 55 having a second motor axis 56. The second eccentric 51 is mounted to the second motor axis 56 by means of a mounting element 57 formed integrally with the second eccentric 51 and a fixation element 58 screwed to the mounting element 57 using screws 59.

[0048] As indicated in Figs. 2, 3 and 10, the first transfer element 33 is guided by a guide 70 provided in the main frame 69 of the device 1 , and the second transfer element 53 is guided by a guide 71 provided in the main frame 69 of the device 1 . In Fig. 10, it is shown that the opener element 40 near the protrusion 49 comprises a cavity 72 that allows that the operating pins 44, 45, 46, 47 can pass through the cavity 72, in particular when the opener element 40 is in the second operating position. The thread guiding device 4 is arranged fixed in position and with screws 73 to the main frame 69. The guiding element 66 is part of a plate 78 that is fixed with screws 74 and 75 to the guiding element 64 of the thread guiding device 4. In order to set the angle between the guiding element 66 and the guiding element 64, the screw 75 can be moved along at least one opening 76, 77 in the plate 78.

[0049] It will be clear to the person skilled in the art that in case the device 1 comprises only one clamping unit 20, 21 , a displacement of the opener element 40 in the feed direction is not necessary and the opener element 40 can be arranged fixed in position in the operating position as shown in Fig. 4. It is also clear that the feed direction does not necessarily need to be linear and perpendicular to the clamping direction, but according to an alternative, for example, can run along a circular arc that extends essentially perpendicular to the clamping direction.

[0050] The device and the method for clamping a weft thread according to the invention are not limited to the embodiments shown and described by way of example, but can also comprise variants and combinations of these embodiments that fall under the claims.

Claims

1 . Device for clamping a plurality of weft threads (7, 8, 9, 10) comprising at least one clamping unit (20, 21 ), a support element (16), and an opener element (40) with at least one finger (41 , 42, 43), wherein the at least one clamping unit (20, 21 ) comprises an abutment element (26, 27) fixedly attached to the support element (16), at least one clamping element (22, 23, 24, 25) moveably mounted to the support element (16) and arranged at a side of the abutment element (26, 27), and at least one force element (28, 29), wherein the at least one clamping element (22, 23, 24, 25) together with the abutment element (26, 27) defines a clamp (60, 61 , 62, 63), wherein the at least one force element (28, 29) forces the at least one clamping element (22, 23, 24, 25) towards the abutment element (26, 27), and wherein the support element (16) and the opener element (40) are mounted displaceable relative to each other in a clamping direction (14), characterized in that each clamping element (22, 23, 24, 25) is pivotally mounted to the support element (16) about a pivot axis (17, 18) perpendicular to the clamping direction (14), and in that the opener element (40) is adapted to be arranged in an operating position, wherein when the opener element (40) is arranged in the operating position, upon a relative displacement between the support element (16) and the opener element (40) the at least one finger (41 , 42, 43) interacts with one of the clamping elements (22, 23, 24, 25) for causing said clamping element (22, 23, 24, 25) to pivot about the pivot axis (17, 18) against the force of the at least one force element (28, 29) for opening the associated clamp (60, 61 , 62, 63).

2. The device according to claim 1 , characterized in that each clamping element (22, 23, 24, 25) is provided with an operating structure (44, 45, 46, 47) displaced from the pivot axis (17, 18) for interacting with the at least one finger (41 , 42, 43) of the opener element (40) upon a relative displacement between the support element (16) and the opener element (40).

3. The device according to claim 2, characterized in that the operating structure (44, 45, 46, 47) is an operating pin protruding from a side surface of the respective clamping element (22, 23, 24, 25), wherein in particular the operating pin is arranged between the pivot axis (17, 18) of the respective clamping element (22, 23, 24, 25) and a clamping position for a weft thread (7, 8, 9, 10).

4. The device according to claim 1 , 2 or 3, characterized in that two or more clamping units (20, 21 ) are provided, wherein the opener element (40) is mounted displaceable between the operating position and a rest position in a feed direction (15) essentially perpendicular to the clamping direction (14) at a fixed height in the clamping direction

(14) , and wherein the support element (16) is mounted displaceable in the clamping direction (14), so that when the opener element is in the rest position by displacing the support element (16) in the clamping direction (14) a selected clamping unit (20, 21 ) can be placed in front of the at least one finger (41 , 41 , 42) of the opener element (40).

The device according to any one of claims 1 to 4, characterized in that two clamping units (20, 21 ) are provided, wherein the opener element (40) comprises one central finger (41 ) and two outer fingers (42, 43) displaced from the central finger (41 ) in the feed direction (15), wherein the opener element (40) is moveable in the feed direction

(15) between a rest position, a first operating position and a second operating position, wherein the opener element (40) when arranged in the first operating position or in the second operating position interacts with one of the clamping elements (22, 23, 24, 25) upon a relative displacement between the support element (16) and the opener element (40) in the clamping direction (14), so that one of the central finger (41 ) or the two outer fingers (42, 43) interacts with one of the clamping elements (22, 23, 24, 25) for causing said clamping element (22, 23, 24, 25) to pivot about the pivot axis (17, 18) against the force of the at least one force element (28, 29) for opening the associated clamp (60, 61 , 62, 63) or for reducing a clamping force at the associated clamp (60, 61 , 62, 63).

The device according to claim 5, characterized in that the outer fingers (42, 43) are provided at either side of the central finger (41 ) in the clamping direction (14) and displaced from the central finger (41 ) in the clamping direction (14), wherein a distance between the central finger (41 ) and each outer finger (42, 43) at least essentially equals to a distance between the abutment elements (26, 27) of the two clamping units (20, 21 ).

The device according to claim 5 or 6, characterized in that the central finger (41 ) is formed such that the central finger (41 ) does not interfere with the clamping elements (22, 23, 24, 25) upon a relative displacement between the support element (16) and the opener element (40) in the clamping direction (14), when the opener element (40) is in the second operating position.

The device according to any one of claims 1 to 7, characterized in that a first driving device (30) comprising a first motor (35) is provided for a displacement of the support element (16) in the clamping direction (14), wherein in particular the first driving device (30) comprises a first eccentric (31 ) driven to pivot about a first drive axis (32) perpendicular to the clamping direction (14).

9. The device according to claim 8, characterized in that the first driving device (30) further comprises a first transfer element (33) mounted slidably, wherein the first eccentric (31 ) drives the first transfer element (33) to move the first transfer element (33) to-and-fro in the clamping direction (14) upon rotation of the first eccentric (31 ).

10. The device according to claim 9, characterized in that the first transfer element (33) is a first frame, wherein the first eccentric (31 ) is arranged inside the first frame, and wherein in particular a wear protection ring (34) is provided between the first eccentric (31 ) and the first frame.

1 1 . The device according to any one of claims 1 to 10, characterized in that a second driving device (50) comprising a second motor (55) is provided for a displacement of the opener element (40) in the feed direction (15), wherein in particular the second driving device

(50) comprises a second eccentric (51 ) driven to pivot about a second drive axis (52) essentially perpendicular to the feed direction (15).

12. The device according to claim 1 1 , characterized in that the second driving device (50) further comprises a second transfer element (53) mounted slidably, wherein the second eccentric (51 ) drives the second transfer element (53) to move the second transfer element (53) to-and-fro in the feed direction (15) upon rotation of the second eccentric

(51 ) .

13. The device according to claim 12, characterized in that the second transfer element (53) is a second frame, wherein the second eccentric (51 ) is arranged inside the second frame, and wherein in particular a wear protection ring (54) is provided between the second eccentric (51 ) and the second frame.

14. Weaving machine comprising a device (1 ) according to any one of claims 1 to 13.

15. Method for clamping weft threads with a device (1 ) comprising at least one clamping unit (20, 21 ), a support element (16), and an opener element (40) with at least one finger (41 , 42, 43), wherein the at least one clamping unit (20, 21 ) comprises an abutment element (26, 27) fixedly mounted to the support element (16), at least one clamping element (22, 23, 24, 25) moveably mounted to the support element (16) and arranged at a side of the abutment element (26, 27), and at least one force element (28, 29), wherein the at least one clamping element (22, 23, 24, 25) together with the abutment element (26, 27) defines a clamp (60, 61 , 62, 63), wherein the force element (28, 29) forces the clamping elements (22, 23, 24, 25) towards the abutment element (26, 27), and wherein each clamping element (22, 23, 24, 25) is pivotally mounted to the support element (16) about a pivot axis (17, 18) perpendicular to a clamping direction (14), the method comprises displacing the support element (16) relative to the opener element (40) in a clamping direction (14) while the opener element (40) is arranged in an operating position, wherein the at least one finger (41 , 42, 43) interacts with one of the clamping elements (22, 23, 24, 25) for causing said clamping element (22, 23, 24, 25) to pivot about the pivot axis (17, 18) against the force of the at least one force element (28, 29) for opening the associated clamp (60, 61 , 62, 63).