Apparatus for the selection of shedding devices by means of bending elements

Abstract: A shedding apparatus for Jacquard-type weaving- and knitting machines can simply make use of piezo-electric bending elements (9,19) for the selection of shedding devices, under the condition that the complementary hooks (2,12) are pliable hooks which are elastic mounted on one of the ascending- and descending parts of the shedding devices. Additionaly the selection of shedding devices can be realised with only one bimorf bending element (9) per harness cord (26).

Description: The present invention refers to an apparatus for the selection of shedding devices in a Jacquard-type weaving machine comprising complementary up- and downwards moving hooks interconnected by one and the same cord, a bending element co-operating with suspension hooks to provide a locking position and a release position for said complementary hooks, and complementary knives co-operating with said complementary hooks to perform the needle position selection via said cord. It makes applications in weaving machines suitable for weaving patterns. The use of piezo-electric bending elements for the selection of the complementary hooks which are interconnected by a filiform element and a pulley, so that they can only move in the opposite direction, is already known. Document BE-08900181 describes a driven clamping system for the selection of complementary hooks belonging to a shedding device of a weaving machine intended for the weaving of patterns. By means of an electromagnet, an elastic positioned armature will or will not be attracted, so that the armature is brought as an elastic hook or a pivoting hook into a locking position. This electromagnetic action goes over an air grap and thereby requires quite some electric energy. This energy supply is partially converted into heat causing the selection equipment to heat up and thus influence the atmosphere in the weavery. Document DE-PS-4309983 describes a selection apparatus that makes use of bimorf piezo-electric bending elements as selection elements of the shedding devices. These bending elements adapt to different bending forms under the influence of an electric tension, similar to the operation of a bimetal. The piezo-electric elements use very little energy. It can be compared with the charging energy of a small condenser. The piezo-electric elements develop no heat. Hence these elements form an important alternative for the electromagnetic selection of the hooks of a shedding device in a weaving machine. The disadvantage of piezo-electric bending elements however is that, at deformation, they are not naturally capable of supplying a mechanical energy of useful magnitude in case of displacement of the extremity over a distance of a few millimeters. Hence these elements are not useful when any mechanical resistance in the element to be moved must be overcome. In this existing selection apparatus, the piezo-electric selection elements are sideway-retractable blocking elements which, through supply of an electric tension, are forced to move sideways and transverse on the motion direction of an extension of a pivoting click in release position. Once in a locking position, a drawback spring pushes the extention of the pivoting click against the piezo-electric element. When selection is required, and locking must occur, one of the knives with corresponding hooks is in an upper position and the pivoting click is pushed to the side, so that a locking space is created on the other side of the click. Only the piezo-element is energized, so that their is no frictional resistance. As the pivoting clicks are positioned on a fixed part of the selection apparatus, they are subject to pollution by dust. If the pivoting clicks become dusty, the bending elements must overcome a certain friction when they bend from the locking position just behind the extension of the hook to the release position just outside the motion trajectory of the extension piece. The total lack of force to overcome a mechanical resistance, remains the main cause why, so far, these elements have found no extended application in selection elements for shedding devices in weaving machines. The purpose of present invention is to remedy this. With the present invention this purpose is reached by means of an apparatus as described in the introductory part of claim 1. This selection apparatus is charachterised by the fact that each said suspension hook is elastically mounted, by means of a drawback spring, on a corresponding up- and down moving part comprising the corresponding complementary hook, whereas said bending element is adapted to block and unblock the trajectory of said elastically mounted suspension hooks towards their locking position through a detention pin. In a special execution the suspension hook is mounted by means of a flat drawback spring on the up and down going part of the selection apparatus, in particular on a complementary hook. In accordance with a particularity of the invention the suspension hook is provided with a cam at the hook-side adapted to latch on a projection provided on the frame of the apparatus. In accordance with a futher development of the invention, the projection on which the suspension hook latches, is protected by a bending piezo-electric selection element. In accordance with the invention, the selection apparatus comprises only one single bending element per harness cord, thus one for both complementary hooks. The bending element is centrally positioned in a sleeve of the weaving machine's frame, midway between the locking positions of the two suspension hooks. In a specific embodiment, the free end of the bending element holds a T-piece provided on both sides, with a detention pin, whereby the middle leg of the T-piece fits exactly in said sleeve and forms a guiding element when the bending element moves sideways between a locking position and a release position of the two suspension hooks. The detention pins, provided on both sides of the T-piece, are intended to lock the elastic suspension hooks in their trajectory. Preferably, each suspension hook shows a recess on its upper side, parallel with abovementioned sleeve on the frame. The recess is higher than the detention pin itself, so that pull-out of the bending element is not obstructed, when a suspension hook is latched on a projection. The bending element is positioned in such a way that its natural, non-energized position, corresponds to the release position and the suspension hook can pull-out side ways when the complementary hook is lifted. These characteristics and other particularities of the invention will become evident from the following description and with reference to the enclosed drawings; which illustrate the invention by way of example, and not in a restrictive sense. In these drawings : Figure 1 is a front view of a selection apparatus with only one single piezo-electric bending element in accordance with the invention; Figure 2 is a vertical cross-section following the line I-I in the apparatus shown in figure 1; Figure 3 is a cross-section at larger scale following line III-III of the T-piece which is mounted on the free extremity of the bending element. In these drawings the same reference signs indicate identical or equivalent elements. As shown in figure 1, an apparatus for the selection of shedding devices in a Jacquard-type weaving machine, suitable for the weaving of patterns, comprises two complementary hooks 2, 12 which are interconnected by one and the same cord 21. The complementary hooks 2, 12 move up and down with complementary knives 1, 11 along a vertical frame 10, divided in a larger rectangular base frame 20 and a narrower upper part 22, in which a vertical sleeve 24 is provided. The upper part 22 and the base frame 20 are separated by two projections 7 and 17. At the top of sleeve 24 of the upper part 22 a piezo-electric bending element 9 is clamped on one side. Electric wires 23 are provided for the power supply to bending element 9, the free extremity of which can pull-out between a locking position and release position (shown as dotted line in figure 2) of a suspension hook 6, 16 attached on each complementary hook 2, 12 by means of a flat drawback spring 3. As shown in figure 1 the flat drawback spring is provided with a cam 4. When the piezo-electric element is energized, it is bent by the tension, transverse on the motion direction of suspension hooks 6, 16; T-piece and the two detention pins 8, 18, leave their locking positions located on the trajectory of suspension hooks 6, 16 and takes a release position, located outside the trajectory of the suspension hooks. Detention pins 8, 18 serve as selection elements to lock elastic suspension hooks 6, 16 in their trajectory. Even if one suspension hook 6, 16 is latched on a projection 7, 17 the T-piece of the piezo-electric bending element can freely bend without resistance, from the locking position to the release position. The suspension hook shows a recess at its upper side, parallel with abovementioned frame sleeve, and higher than the detention pin itself in order to prevent pull out of the bending element, when a suspension hook 6, 16 is latched on a projection 7, 17. The bending element is positioned in such a way that its natural non-energized position corresponds to the release position in which suspension hook 6, 16 can freely pull-out side-ways when the complementary hook is lifted. The piezo-electric bending element 9 can pull-out freely between the locking- and release positions and reverse, without needing to overcome a mechanical resistance. The two complementary knives 1 an 11 of the selection apparatus move up and down in opposite phase. The complementary hook 2 moves upwards along with 1. Suspension hook 6, which is mounted on complementary hook 2, is pushed backwards by projection 7. The action of spring element 3 of hook 2 pushes cam 4 against projection 7 and the latch element 5 of hook 6 also experiences a drawback force from spring 3. In this position detention pin 8 can freely move according to a direction contained in the plane of figure 2. Under influence of an electric tension the piezo-electric element bends in a direction that is perpendicular to the plane of figure 1 and the T-piece, equiped with detention pins 8, slides out of the trajectory of suspension hook 6, 16. If the knives move, 1 now downwards and 11 upwards, cam 4 will leave projection 7 and, through the drawback force of spring 3, suspension hook 6 will hook onto projection 7. This way suspension hook 6, 16 will be held in an upper position while knife 1 is moved downwards. Complementary hook 12 is brought upwards with knife 11, pulley-block 31 is lifted, as will cord 25, which is interconnected to one or more harness cords that drive the healds for the lifting of the warp ends. With each interruption of the electric power supply piezo-element 9 returns to its original straight position so that the T-piece and detention pin 8 return to a locking position just above projection 7 in the trajectory of hook 6. In this locking position, suspension hook 6 pushes, when knife 1 is descending, with its external face against detention pin 8. Suspension hook 6 slides over detention pin 8, subsequently over projection 7 and the complementary hook 2 therefore descends with knife 1. Pulley-block 31 remains on the same level and harness cord 25 therefore remains in the lower position. The simultaneous control of the selection devices at two different locations by means of only one bending element, is made possible thanks to the fact that the complementary hooks execute simultaneous motions in opposite directions. The knives never ascend together. The positions of detentions pins 8 and 8' can then be changed during a short time without having a direct effect on one of the two selection devices corresponding to the same bending element. The energized situation of the bending element, which is shown in figure 2 in dotted line and which corresponds to the unlocked position, is only maintained as long as necessary to release the trajectory of the head of the hook. It is obvious that the selection elements are subject to continously alternating bending tensions at a very high rhythm imposed by the production speed. In accordance with the invention, the selection apparatus has the advantage that it : allows a compact machine construction, hardly radiates any heat and is very reliable, even if the weaving machine is polluted after a while by dust and oil. The drawback springs may, without any disadvantage or risks of magnetic remanention, be manufactured from spring steel. Such steel offers an excellent resistance against fatigue under continuous bending stress at very high rhythm.

Claims: Apparatus for the selection of shedding devices in a Jacquard-type weaving machine comprising complementary up- and downwards moving hooks (2,12) interconnected by one and the same cord (21), a bending element (9) co-operating with suspension hooks (6,16) to provide a locking position and a release position for said complementary hooks (2,12), and complementary knives (1,11) co-operating with said complementary hooks (2,12) to perform the selection of the shedding devices via said cord (21), characterised in that each said suspension hook (6,16) is elastically mounted, by means of a drawback spring (3,13), on a corresponding up- and down moving part comprising the corresponding complementary hook (2,12), whereas said bending element (9) is adapted to block and unblock the trajectory of said elastically mounted suspension hooks (6,16) towards their locking position through a detention pin (8,18). Apparatus according to claim 1 characterised in that said bending element (9) comprises a piezo-electric bending element. Apparatus according to claim 1 or 2, characterised in that said suspension hook (6,16) is mounted on the corresponding complementary hook (2,12) by means of a flat drawback spring (3,13). Apparatus according to claim 2 and 3, characterised in that the piezo-electric element (9) bends in a direction perpendicular to the plane of the bending of the flat drawback spring (3,13) of the suspension hook (6,16). Apparatus according to claim 4, characterised in that each said suspension hook (6,16) is provided at its hook-side with a cam (4,14) adapted to latch on a projection (7,17) provided on a frame (10) of the apparatus, whereas piezo-electric bending element (9) is adapted to prevent the suspension hook (6,16) from latching on the projection (7,17). Apparatus according to anyone of the preceding claims , characterised in that it comprises one single bending element (9) for both suspension hooks (6,16) of the complementary hooks (2,12). Apparatus according to claim 6, characterised in that the bending element (9) is centrally positioned in a sleeve (24) of a frame (10) of the apparatus, between the locking positions of two suspension hooks (6,16). Apparatus according to anyone of claim 6 or 7, characterised in that the free end of the bending element (9) holds a T-piece provided with a detention-pin (8,18), on both sides, whereby the middle leg of the T-piece fits exactly in said sleeve (24) and forms a guiding element when the bending element (9) moves sideways between a locking position and a release position of the two suspension hooks (6,16). Apparatus according to claim 8, characterised in that the detention pins (8,18) mounted on both sides of the T-piece are adapted to block and unblock the trajectory of the elastically mounted suspension hooks (6,16). Apparatus according to anyone of claim 7,8 and 9, characterised in that each suspension hook (6,16) shows a recess at the upper side parallel with said sleeve (24) of frame (22) and higher than the detention pin (8,18) in order not to prevent a pull out movement of the bending element (9), when a suspension hook (6,16) is latched on projection (7,17). Apparatus according to anyone of claims 2 to 10, characterised in that the piezo-electric bending element (9) is positioned in such a way that its natural not energized position corresponds to the release position in which the suspension hook (6,16) can freely move sideways when the complementary hook (2,12) is lifted.

Inventors: DERUDDER CARLOS, DEWISPELAERE ANDRE, DERUDDER, CARLOS, DEWISPELAERE, ANDRE, Dewispelaere, André
Applicants: WIELE MICHEL VAN DE NV, N.V. MICHEL VAN DE WIELE
Application year: 1995
Main classification: D03C3
IPC codes: D03C3