Patent Publication Number: US-3880198-A

Title: Weaving machine

Description:
1451 Apr. 29, 1975 O United States Patent 11 1 Vermeulen 1 WEAVING MACHINE [7S] lnventor: Geert Jan Vermeulen, Deurne. Netherlands [73] Assignee: Ruti-Te Strake B.V.. Deurne, Netherlands [22] Filed: May 7, 1973 [21] Appl. No.1 357,842  
 [30] Foreign Application Priority Data May 10. 1972 Netherlands 7206367 [52] US. Cl. 139/127 P; 139/194; 139/370 [51] Int. Cl. D03d 47/28: D03d 47/34 [58] Field of Search 139/127 R. 127 P. 194. 139/370 [56] References Cited UNITED STATES PATENTS 3.399.701 9/1968 Tcstrake 139/127 P 3.532.138 10/1970 Schlappi 139/370 3.658.098 4/1972 Van Mullekom 139/194 3.744.533 7/1973 Yuno et al. 139/194 I f! 11 111111 I 8 P Primary E.\&#39;amin &#39;rHenry S. .laudon Attorney. Agent. or Firm-Marshall &amp; Yeasting [57] ABSTRACT A weaving machine comprises two sheets of warp threads which are momentarily held in diverging planes to form a weaving shed. and a main blowing nozzle arranged in a position at one side of such shed to introduce a weft thread through such shed by propelling the weft thread by means of a fluid discharged from the nozzle. A reciprocable reed comprises a plurality of blades arranged parallel to the direction of reciprocation. each blade having a notch on its beating edge. such notches being aligned and forming a tunnel less than 8 mm. in diameter which in the retracted position of the reed has one end aligned with the main blowing nozzle. An air injector carried by the reed is mounted in the other end of such tunnel and is adjustable longitudinally of the tunnel to accommodate various widths of cloth being woven. such air injector having a central suction channel arranged to receive the head end of a weft thread propelled through the channel by the main blowing nozzle in order to maintain tension on the weft thread during the beating up movement of the reed.  
 2 Claims. 2 Drawing Figures WEAVING MACHINE BACKGROUND OF THE INVENTION The invention relates to a weaving machine of the type in which a transport tunnel for the weft threads is defined by a plurality of blades. each having a substantially U-shaped notch. which are movable along with the reed. and in which the weft threads are introduced from one side of the weaving shed to the other through said tunnel by the action of a flowing fluid discharged from of a main blowing nozzle positioned at one side of the shed. tensioning means being provided at the other side of the shed adapted to tension at weft thread that has been inserted into the shed and to keep said thread in a tensioned state during the beating up movement.  
  Such a weaving machine is known. In this machine the tensioning means comprise a mechanism formed by a catching means movable along with the reed and by a clamping means cooperating with said catching means during the beating up movement of the reed. Another method of catching and tensioning the weft yarn inserted through the shed is described in British Patent specification l.t)88.749. according to which a plurality of catching threads. running parallel to the warp threads. are used, which are moved apart and brought together again in synchronism with the opening and closing of the shed so as to receive the end of the weft yarn extending beyond the shed. and are subsequently twisted together for trussing said ends and thereby keeping the weft yarn taut. In still another weaving machine of the type above referred to a special catching and tensioning lever mechanism for tensioning the wefts is mounted longitudinally adjustable on the reed. This mechanism has the advantage that it may be adjusted to different weaving widths. but it is of a relat&#39;nely complicated construction and control.  
  A common disadvantage of the known devices for tensioning wefts is that they do not provide for compensating for changes in length and differences in elasticity.  
 SUMMARY OF THE INVENTION Now according to the invention the tensioning means is constituted by an air injector carried by the reed and having a centrally disposed suction channel aligned with the end of the transport tunnel remote from the main blowing nozzle.  
  The great advantage of an air injector as a tensioning means for the wefts is that its tensioning effect is independent of any changes in length and variations as a result of differences in elasticity which are automatically compensated. while the weft end which remains extending beyond the selvage after the weft has been bound in. is automatically retracted from the injector by the beating movement of the reed. The tensioning means are of a simple construction. without moving parts and without special control means.  
  It is to be noted that tensioning a textile thread by means of an air injector is already generally known per However. the problem with an air injector when applied to the purpose in view is that this air injector must be able to catch the head end of a weft inserted into the shed. from a plurality of positions which may be taken by the weft head end within the shed.  
  In view of the latter circumstance the suction nozzle which usually is mounted at the side of the machine remote from the weft blowing nozzle. for receiving the head end of an inserted weft and for later on discharging the cut end of said weft. generally has relatively large dimensions. The weft cannot be drawn sufficiently tensioned by such a largely dimensioned suction nozzle; therefore in well-known weaving machines. apart from such a suction nozzle there are additional means for tensioning the weft.  
  Therefore. in accordance with the present invention it is essential that the position of the head end of the weft at the end of the weft inserting phase be rather accurately defined. so that is will be sufficient to use an air injector which is of relatively small dimensions and therefore is indeed suitable as a tensioning means. and operates with an economically justified air consumption. This condition of a relatively accurately defined weft head end position is satisfied by the present weaving machine in which the transport of the weft through the shed occurs through a transport tunnel defined by suitably shaped blades. more particularly a tunnel which is delimited by a plurality of blades moving along with the reed. which tunnel dependent on the weaving width cooperates with one or more auxiliary blowing nozzles spaced along the weaving width.  
  The latest developments in a weaving machine of the last mentioned type led to an embodiment in which the wefts are transported through a tunnel having a cross section less than 8 mm. wide. Now exactly below this limit the application of an air injector as the device for tensioning the \vefts has appeared to be not only practically but also technically feasible.  
  Therefore. the invention relates to a weaving machine in which the cross sections ofthe reed tunnel and the suction aperture of the air injector respectively are less than about 8 mm. wide.  
  A special advantage of the air injector as a weft tensioning means is obtained when used in combination with a weft detecting means. For weft detecting purposes it has been proposed. e.g. in British patent specification l.236.346 to use a light source and a photoelectric receiver cooperating therewith. The light source emits a single light ray in a transverse direction through the tunnel-like transport path of the weft. Since the position of the weft in its transport path. as indicated above. may strongly vary. it is necessary with such a detection device to constrain movement of the inserted weft transverse to the weft direction in order to be sure that the inserted weft will positively interrupt the light ray. Now when an air injector is used as a means for tensioning the weft this restriction of the transverse movement is automatically obtained. Extensive experiments have indeed shown that each air injector imparts a certain twinning to the weft resulting in making the weft balloon-shaped. by this minimal balloon shape the weft tensioned in the relatively small cross section of the air injector according to the invention will in any case interrupt the light ray which is e.g. directed diametrally through said cross section. Preferably the light source and the photoelectric receiver are provided in the wall of the discharge channel of the air injector.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. I is a perspective view of part of the reed of a pneumatic weaving machine. provided with a device for tensioning the wefts according to the invention and FIG. 2 is a longitudinal section through the tensioning device according to the invention. in which at the same time the electrical diagram of the weft detection means is shown.  
 DESCRlPTlON OF THE PREFERRED EMBODIMENT In FIG. 1 a tunnel-like transport channel is formed in the weaving shed 3. constituted by the upper and low er warp threads 1 and 2. and by the reed blades 5 each having a substantially L-shaped notch opening towards the beating up line 4. which blades are encased in the reed beam 6.  
  The reed comprising the reed beam with the blades 5 is in HO. 1 in its retracted position. in this position the transport tunnel formed by the reed blades 5 is located opposite the weft inserting nozzle schematically indicated at 7. which is adapted to introduce a weft by means of an airjet into the said tunnel. Usually a weaving loom should be able to weave cloths of different widths. Therefore the reed generally extends at the side remote from the weft blowing nozzle 7 beyond the corresponding side edge of the cloth by a varying distance. In the end portion ofthe reed tunnel extending beyond the side edge of the cloth the air injector indicated 8 has been provided which is mounted. adjustable in the direction of the cloth width. on the reed beam 6 by means of a connecting bracket 9. The airinjector 8. which is shown in FIG. 2 in longitudinal section. has a construction which is known per se and corresponds to that of the weft blowing nozzle. The injector serves to receive the weft launched by the weft inserting nozzle 7 and also to tension it and keep it in a tensioned state during the heating up movement of the reed. To this end the injector 8 is supplied with air at the same time as or very shortly after the nozzle 7 and at least up to and including the end phase of the beating up movement ofthe reed. The connection point for a flexible air hose is indicated at 9&#39;. When the reed is advanced to its beating position the end of the weft inserted into the cloth is retracted from the injector 8 and this may be received in a suction nozzle in a manner known per se. and may subsequently be cut by a cutting device. Of course it is then important that the end portion of the weft extending beyond the edge of the cloth be not longer than the distance through which the reed and therefore the air injector 8 move between the beating up position and the retracted position. Only then will the evtending weft end be freed with certainty from the injector 8.  
  The air injector 8 further comprises the components ot&#39;a weft detecting device. namely a light source 10 and a photoelectric receiver ll.  
  The light source it] may be constituted by a miniature incandescent lamp. a Ga-As diode or similar small light source and is provided either directly in the wall of the discharge tube 8&#39; of the injector 8. or may he in o tical communication with a fibre optics sunk into a radial bore in that wall. The photoelectric receiver 1] e.g. comprises a photo diode which is provided diametrally opposite to the light source 10 in the wall of the discharge tube 8&#39;.  
  Although the light ray emitted diametrally by the light source 10 through the discharge tube 8&#39; only covers a very narrow portion of the cross section (being about 3 mm. wide) of that tube. a weft caught by the injector 8 will yet. as explained above. interrupt said light ray with certainty. Asa consequence of that interruption the photo diode 11 issues a signal as a sign that indeed a weft has been inserted from the other side of the machine. This signal may. as indicated in the diagram according to FIG. 2, be converted by an amplifier 12 into an electric signal necessary to keep the electric circuit of the drive of the machine energized.  
 I claim:  
  1. A weaving machine comprising two sheets of warp threads which are momentarily held in diverging planes to form a weaving shed. and a main blowing nozzle arranged in a position at one side of such shed to propel a weft thread through such shed by means of a fluid discharged from said nozzle. wherein the improvement comprises a. a reciprocable reed comprising a plurality of blades arranged parallel to the direction of reciprocation. each blade having a notch in its beating edge. such notches being aligned and forming a tunnel having a crosssection less than 8 mm. wide which in the retracted position ofthe reed has one end aligned with the main blowing nozzle.  
 b. an air injector nozzle which is located wholly within said tunnel and has a central suction channel arranged to receive the head end of a weft thread propelled through said tunnel by the main blowing nozzle in order to maintain tension on the weft thread during the beating up movement of the reed. and a bracket on which the injector nozzle is mounted. which is slidably secured to the reed and is arranged to locate the injector nozzle in the end of said tunnel remote from the main blowing nozzle in a longitudinally adjusted position to accomodate the width of cloth being woven.  
  2. A weaving machine according to claim I. in which at detecting device is provided for detecting the wefts inserted into the transport tunnel comprising a light source and a photoelectric receiver. characterized in that said detecting device is provided in the wall of the injector,