Abstract:
A heald frame for a weaving machine includes stops ( 15, 16 ) made of a material with shock-absorbing properties associated with the ends of the healds ( 10 ). A gap is provided between the heald ends and the stops, such gap ensuring that the healds can be moved along guide rails forming part of the heald frame while reducing noise and potentially damaging vibrations. The healds are held on the guide rails with play and are moved by and limited in their movements in a longitudinal direction by the stops.

Description:
CROSS REFERENCE TO RELATED APPLICATION  
       [0001]     This application is a continuation application of U.S. patent application Ser. No. 10/149,426, filed on Jun. 24, 2002. 
     
    
     BACKGROUND  
       [0002]     1. Field of the Invention  
         [0003]     The invention relates to weaving machine heald frame fitted with an upper and a lower cross-sectionally contoured rail, hereafter rail, for holding the healds which are held by guide elements located at the ends of the healds to the rails.  
         [0004]     2. Related Art  
         [0005]     Several heald frames of this kind constitute a so-called heald frame system. The individual heald frames of this system are alternatingly raised and lowered by a heald frame machine in order to form sheds using heald-guided warps between which fillings may be inserted. The rails and the heald guide elements typically have geometries such that, in one direction of heald frame motion, one of the rails rests by a drive surface against a cooperating surface of the heald guide elements to thereby drive such healds. In the other direction of motion, a drive surface of the other rail will drive a cooperating surface of the heald guide elements which are associated with it. Because the heald frames and the healds expand on account of heat and forces applied by the warps, and because manufacturing tolerances have to be provided for both, and because additionally the healds must be displaceable along the rails, for instance to insert or repair warps, a play of about 2-3 mm is provided for the healds between the drive surfaces of the rails and the cooperating surfaces of the guide elements. When the frames move up and down, the healds will move by said 2-3 mm relative to the rails. These motions result in impacts causing on one hand noise and on the other hand heald vibrations. At high weaving rates, these motions and particularly the thereby caused vibrations may break the healds and/or the heald frames and/or the warps.  
         [0006]     To avoid such problems, it is known from WO 97/23396 to reduce the play between the healds and the rails by providing one or more shims fitted onto one of the rails to reduce the gap between these heald drive surfaces of this rail and the cooperating surfaces of the heald guide elements down to a slight play of about 1 mm. These shims are made of plastic, and consequently damping is attained as ell. In this manner noise and the risk of damage may be reduced, although some drawbacks may be incurred regarding operability. Because the heald play is reduced longitudinally, the longitudinal movability of the healds and their movability in the direction of the rails also is restricted. As a result, an operator repairing a yarn break may be somewhat hampered and it is even possible that the healds could be bent in the course of making repairs.  
       BRIEF SUMMARY OF THE INVENTION  
       [0007]     The objective of the present invention is the reduction of noise and furthermore the reduction of potential damage caused by heald vibration.  
         [0008]     This problem is solved in that a damping stop made of material with damping properties is provided adjacent at least one end of the healds and in that the gap between this stop and the adjacent end of the healds shall be smaller than the gap between the guide element ends and the rail surfaces opposite the stop.  
         [0009]     In this design the healds shall be driven at least in one direction by the damping stop or they shall impact the stop in one direction, as a result of which noise will be significantly reduced. Also, at least when the healds are driven in one direction or when impacted in one direction, damping shall take place and heald vibrations will be substantially reduced. This reduction in noise and adverse effect of vibrations also shall be the case for plays of larger magnitudes, for instance of 2-3 mm or more, and consequently there would be no restriction on the relative movability of the healds in the longitudinal rail direction or in their own longitudinal direction. Means are thus provided to the skilled designer to reduce the danger of noise and creaking movability or shiftability by controlling the play or to trade off somewhat more noise and somewhat greater danger of vibrations against improved heald movability.  
         [0010]     Preferably stops shall be fitted at both heald ends. In this manner driving of the healds and the impact of the healds on drive elements takes place solely against the damping stops. The rails in accordance with this design merely provide lateral guidance. Consequently the longitudinal heald play may be selected almost arbitrarily, that is, it may be comparatively small and entail less movability and longitudinal excursion, or it may be comparatively large with commensurately good movability and longitudinal excursion. 
     
    
     DESCRIPTION OF THE DRAWINGS  
       [0011]     Further features and advantages of the invention are elucidated in the description below of the illustrative embodiments shown in the attached drawings.  
         [0012]      FIG. 1  is a schematic front view of a heald frame of the invention,  
         [0013]      FIGS. 2, 3  are cross-sections along line II-II of  FIG. 1  in different frame positions, and  
         [0014]      FIGS. 4, 5  are cross-sections similar to  FIGS. 2, 3  of a modified embodiment with a unilateral stop 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0015]     The heald frame  1  shown in  FIG. 1  is a frame consisting of two supporting side sidebars  2  and  3  and two supporting crossbars  4 ,  5 . Rails  6 ,  7  are affixed by brackets  8  in the zone of the mutually facing sides of the supporting crossbars  4 ,  5 . These rails  6 ,  7  receive lamellar healds  10  each fitted centrally with a yarn eyelet  12  to receive a warp. The healds  10  are guided by guide elements  13 ,  14  on the rails  6 ,  7 . The rails  6 ,  7  are fitted for example at their longitudinal ends with limit stops  11  to prevent the healds  10  from slipping off. The rails include opposed ends located respectively towards and away from the cross bars to which they are attached, said rail ends facing adjacent guide ends defining the limits of play between the rails and the guides, in a well known manner.  
         [0016]     The ends of the healds  10  are associated with strip shaped heald stops  15 ,  16  mounted on the crossbars  4 ,  5  and which drive the healds  10  in the manner described below in relation to  FIGS. 2 and 3 . The guide elements  13 ,  14  of the lamellar healds  10  are dimensioned in such a way relative to the rails  6 ,  7  that the rails  6 ,  7  shall guide the healds  10  only laterally, but will not drive the healds via their ends during lifting and lowering movements. The brackets  8  of the rails  6 ,  7  are fastened by screws  9  to the crossbars  4 ,  5 , said screws passing through slots  17  of the brackets  8  ( FIGS. 2, 3 ) running in the longitudinal direction of the healds  10 . In this way the position of the rails  6 ,  7  is adjustable in the longitudinal direction of the lamellar healds  10  relative to the crossbars  4 ,  5 .  
         [0017]     When the heald frame is raised in the direction of the arrow A at the middle shed position, or when it is at its upper end position, then the lower ends of the healds  10  shall rest against the lower damping stop  16  as shown in  FIG. 2 . When the frame is lowered in the direction of the arrow B as indicated in  FIG. 3 , then the healds  10  if in the middle shed position will reverse their relative position and will come to rest by their upper end impacting against the upper damping stop  15 . Because the stops  15 ,  16  are made of a damping synthetic material, the impulse will be decelerated and damped and on one hand the noise shall be much abated, while on the other hand the danger of damage caused by vibrations in the heald  10  is reduced. If then the frame is raised again in the direction of the arrow A as shown in  FIG. 2 , the healds shall on the basis of the warp tension again reverse their position in a substantially impulsive manner in the middle shed zone, and thereafter they will rest by their lower end against the lower stop  16 . Accordingly the healds  10  are moved as described and their longitudinal excursions are limited solely by means of the strip shaped damping stops  15 ,  16  made of damping synthetic material. Therefore the play within which the healds  10  may be moved relative to the upper crossbar  4  and the lower crossbar  5  may be selected as a relatively large play without increasing the danger of more noise and/or damage. If a relatively large play is selected, it will be easier to shift the healds  10  along the longitudinal direction of the rails  6 ,  7  and furthermore to shift them in their own longitudinal direction with respect to the rails  6 ,  7 —this feature being advantageous for an operator repairing a warp break.  
         [0018]     As regards the embodiment shown in  FIGS. 2 and 3 , the upper crossbar  4  and the lower crossbar  5  are fitted with a seat  18  illustratively in the form of a longitudinal groove. The stops  15 ,  16  are strips received in this seat  18  and are affixed for instance by bonding. Such a seat  18  is recommended for new heald frames in accordance with the invention. If on the other hand already extant heald frames are being retrofitted to correspond with frames made in accordance with the invention, other means may be used to mount the strip shaped stops  15 ,  16 . Illustratively the latter may be mounted by fasteners to the crossbars  4 ,  5  in such a way that they rest on the mutually opposite edges. Moreover affixing elements may be used that are affixed to but spaced from the crossbars  4 ,  5 . In the latter case those sides of the strip shaped stops  15 ,  16  which are located opposite the healds  10  shall be appropriately reinforced by a reinforcing rail.  
         [0019]     As shown in the illustrative embodiment of  FIGS. 4 and 5 , a substantial improvement is attained even if only one strip shaped stop  15  is used on one side, that is, as regards this embodiment, at the upper crossbar  4 . In this configuration and as shown in  FIG. 4 , the healds  10 ′ are raised by a drive surface of the upper rail  6 , said drive surface being situated opposite a cooperating surface of the upper guide element  13 ′. In this embodiment, the lower rail  7  is used only to guide the heald  10 ′ transversely. In this embodiment of  FIGS. 4 and 5 , the guide elements  13 ′,  14 ′ of the healds  10 ′ are open toward the brackets  8  and as a result the healds  10 ′ also may be freely displaced in the vicinity of the brackets  8 . As regards another embodiment, the rail  6  and its associated guide element  13 ′ are dimensioned in such a way that they will only be in the transverse guide mode while the healds  10 ′ are driven in a lifting direction by the lower rail  7  which then will rest by one drive surface against a cooperating surface of the guide element  14 ′. Obviously one stop only may be used also in the region of the lower ends of the healds  10 ′, for instance a stop  16  as shown in the embodiment of  FIGS. 2 and 3 .