Patent Publication Number: US-5020573-A

Title: Control mechanism for the selection of weft yarns in rapier looms

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to a control mechanism for the selection of weft yarns in rapier looms provided with presenting needles on presenting levers. Specifically, the control mechanism is controlled by a system of levers from a series of electromagnets. 
     2. Prior Art 
     Various mechanisms exist for the selection of weft yarns in rapier looms. The selected weft yarn must be clamped, cut off and presented to the rapier and, once gripped by the rapier, inserted into the shed. 
     Before that the various possible weft yarns, each run through an eye of the respective presenting needles. These presenting needles are connected to levers, shafts, hook elements, etc., which together form a mechanism which is controlled in one way or another to make the selected presenting needle move with its corresponding weft yarn for the presentation of the weft to the rapier. 
     The object of the invention is such a control mechanism. The problem with such a mechanism lies in the high speed at which rapier looms are currently running, requiring a quick response for presentation of the new weft yarn and for the withdrawal of the previous presenting needle. 
     There are such mechanisms in existence in which each lever, controlling its corresponding presenting needles is on one side continuously under the tensile force of a spring and thus inclined to bring the presenting needle in question back to its rest position, and on the other side cyclically under pressure of a resilient pressure finger which is pushed in by a cam disk and held in this position by an electromagnet for the time that an electric current flows through it, in accordance with the requirements of the fabric. 
     However, this control mechanism lacks reliability regarding control, particularly the high speeds which are presently used in rapier looms. 
     SUMMARY OF THE INVENTION 
     The object of the control mechanism for the selection of the weft yarns in rapier looms according to the invention is to remedy this shortcoming. 
     The control mechanism for the selection of the weft yarns in the rapier looms according to the invention is characterized by the fact, that the presenting needles are controlled by levers mounted freely on an articulating shaft, which is rocked back and forth by an eccentric mounted on the main shaft, without this reciprocating movement making the presenting needles deviate from their rest position. 
     The control mechanism, according to the invention, for the selection of weft yarns in rapier looms, of which the levers controlling the presenting needles hooked in with or without the intervention of an electromagnet according to whether the presenting needle in question is selected or not according to whether the particular pattern of the fabric, is further characterized by the fact that all armature blocks, fastened on the levers provided with hooked handles, are pushed once per turn against their respective electromagnets by a common push bar, mounted on a shaft, which is moved back and forth by being driven by a cam disk mounted on the main shaft. 
     The control mechanism, according to the invention, for the selection of the weft yarns in rapier looms, of which the levers, controlling the presenting needles, hooked with or without the intervention of an electromagnet according to whether the presenting needle in question is selected according to the particular pattern of the fabric, is further characterized by the fact that the current in the electromagnet involved flows in one direction at one time to hold the selected needle in its presenting position and next in the other direction to repel the armature block connected on the lever of the selected needle as soon as the presenting needle involved has to return to its rest position. 
     Further characteristics and advantages of the control mechanism for the selection of the weft yarns in rapier looms according to the invention will appear from the description of this control mechanism with reference to the accompanying figures, without this description and this figure implying a limitation of the invention to this particular embodiment. 
     These and further and other objects and features of the invention are apparent in the disclosure, which includes the above and ongoing written specification, including the claims and the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1--shows a perspective view of the steering mechanism according to the invention. 
     FIG. 2--shows two positions of the selected presenting needle with its levers. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     A control mechanism for the selection of weft yarns in rapier looms according to the invention, as shown in FIG. 1, comprises several parallel shafts. 
     There is first, the main shaft (1), which rotates synchronously with the main shaft of the loom. On this main shaft are rotatably mounted the various presenting needles (2, 3) with their presenting levers (4, 5), with the main shaft (1) as the articulating shaft, about which the presenting levers (4, 5) with their presenting needles (2, 3) can tilt. 
     These same presenting levers (4, 5) have fixed to them small protruding fingers (6, 7), which are coupled to the springs (8, 9), tied to the frame of the control mechanism, that hold the presenting needles (2, 3) in their rest position and bring it back to that rest position after they have been selected and have to return to their rest position. 
     The tilting motion of a selected presenting needle (2, 3) is obtained by a series of levers, the connecting elements (10, 11) of which connect the presenting levers (4, 5) with the control levers (12, 13) along the joints (14, 15) and (16, 17). 
     The control levers (12, 13) are rotatably mounted on the shaft (18), that runs parallel to the main shaft (1), so that the control levers (12, 13) can swivel freely around the shaft (18). 
     The shaft (18) is mounted on the cranks (19) (only one is shown), which rock back and forth around a third shaft (20) also mounted on the cranks, the cranks are driven by an eccentric (21) mounted on the main shaft (1) and link (22). 
     At each rotation of the main shaft of the loom, the main shaft (1) makes one full rotation also and the shaft (18) obtains a back-and-forth motion without the presenting needles (2, 3) deviating from their rest position, because the presenting levers (4, 5) are restrained by the springs (8, 9), while the presenting levers (4, 5) as well as the control levers (12, 13) are mounted rotatably on their respective shafts (1) and (18) and are connected by connecting elements (10, 11) along the joints (14, 15) and (16, 17). 
     The control levers (12, 13) have extensions (23, 24), that end in hooks (25, 26). 
     It suffices to hold back one of these extensions (23, 24) at the time of the back-and-forth movement of the second shaft (18) to make the corresponding lever, along its connecting element, push the presenting lever of the presenting needle selected. 
     To this end an electromagnet of special design is used. 
     Straight across from each extension (23, 24), provided with their respective hooks (25, 26) there is a complementing hook (27, 28), which is part of a right-angled lever (29, 30), which articulates around a fourth shaft (31) parallel to the main shaft (1) in its angular point (32, 33), while the other leg of this right-angled lever (29, 30) is provided with an armature block (34, 35), which can connect to the two poles of an electromagnet (36, 37), with which a magnetic field be created. 
     Straight across from the series of electromagnets (36, 37) is a push bar (38) provided with compression springs, mounted on a fifth shaft (39) parallel to the main shaft (1). 
     This shaft (39), on which the push bar is mounted, is clamped to the cranks (40) (only one crank (40) is shown), which are mounted rotatably on a shaft (41) and rock back and forth with a lever (42) controlled by a cam roller (43), attached to the lever (42) and an extension of the crank involved (40). A cam disk (44) mounted on the main shaft (1) drives the cam roller (43). 
     Because of this design, the push bar (38) pushes at each rotation of the main shaft (1) all the armature blocks (34, 35) against the electromagnets at a time that can be controlled by the position and shape of the cam disk (44). 
     At this point it suffices to energize the electromagnet (36) corresponding to the presenting needle (2) to be selected to hold the armature block (34) against the electromagnet (36), while the armature block (34) is removed from the non-energized magnets under the tensile force of the spring (45), when the push bar (38) moves away from these electromagnets driven by the rocking levers (40, 42) from the cam disk (44). 
     Provided that the right-angled lever (29) with the armature block (34) is held against the electromagnet (36), the hook (25) of the extension (23) of the control lever (12) hooks with the complementing hook (27) of the right-angled lever (29), so that the control lever (12) tilts about the shaft (18) with a outward movement of the shaft (18) about the shaft (20), controlled from the main shaft (1). The tilting motion of the control lever (12) also causes the presenting lever (4) to tilt, so that the presenting needle (2) attached to this presenting lever (4) moves away from its rest position and takes the selected yarn to the rapier (FIG. 2). 
     As soon as a selected presenting needle must return to its rest position, the electromagnet (36) is energized with countercurrent for a very brief period, so that the magnetic field reduces very quickly, thereby causing, e.g., the armature block (31) involved to move away quickly from the corresponding electromagnet (36) under the tensile force of the spring (45). 
     The control mechanism according to the invention has the great advantage of a very brief response time to the position of the presenting needles. With the push bar (38) all armature blocks (34, 35) are pushed against the electromagnets; the selected electromagnet is then energized, so that immediately a very large attraction develops, even with a relatively weak electromagnet. This adhesiveness, as well as the remanent magnetism, is terminated by a sufficiently large countercurrent, so that the armature blocks involved are released immediately and move away from the magnet poles under the tensile force of the springs (45, 46). 
     While the invention has been described with reference to specific embodiments, modifications and variations of the invention may be constructed without departing from the scope of the invention, which is described in the following claims. 
     This control has an immediate effect on the presenting needle involved, which is mounted in such fashion, that the shafts can move freely without obstruction by the springs.