Weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum
A weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum formed of several fixed sectors, each provided with respective support shanks housed in respective seats formed in a static support disk, coaxial to a drive shaft of the weft feeder, and wherein the spacing of said spaced coils on the drum is caused by the oscillatory and tilting movement of several moving sectors, each provided with respective support shanks housed in respective seats formed in a tilting support disk, eccentric and skew with respect to said drive shaft of the weft feeder, and wherein elastic elements are provided, which exert a compressive force on said shanks to keep said fixed sectors and said moving sectors in a position of stable engagement within their respective seats. The fixed sectors and the moving sectors are each provided with a single support shank in the general shape of a trapezoidal right prism, housed in a respective seat consisting of a cavity having a congruent trapezoidal shape, and said elastic elements exert a compressive force on the major base of said support shank having the shape of a trapezoidal right prism.
1 . A weft feeder for weaving looms with spaced thread coils and adjustable-diameter drum (D), wherein said drum (D) is formed of several fixed sectors ( 5 ), each provided with respective support shanks ( 5 g ) housed in respective seats formed in a static support disk ( 6 ), coaxial to a drive shaft (A) of the weft feeder, and wherein the spacing of said spaced coils on the drum (D) is caused by oscillatory and tilting movement of several moving sectors ( 7 ), each provided with respective support shanks ( 7 g ) housed in respective seats formed in a tilting support disk ( 8 ), eccentric and skew with respect to said drive shaft (A) of the weft feeder, and wherein elastic elements which exert a compressive force on said shanks ( 5 g , 7 g ) are provided, to keep said fixed sectors ( 5 ) and said moving sectors ( 7 ) in a position of stable engagement within their respective seats, wherein the fixed sectors ( 5 ) and the moving sectors ( 7 ) are each provided with a single support shank ( 5 g , 7 g ) having a general shape of a trapezoidal right prism, housed in a respective seat consisting of a cavity having a congruent trapezoidal shape, at least to a limited extent of its converging side walls, and wherein said elastic elements exert a compressive force on the major base of said support shank having a general shape of a trapezoidal right prism.
2 . The weft feeder for weaving looms according to claim 1 , wherein said support shanks ( 5 g , 7 g ) of the fixed sectors ( 5 ) and the moving sectors ( 7 ) are in a shape of an isosceles trapezoidal right prism.
3 . The weft feeder for weaving looms according to claim 1 , wherein minor bases of said support shanks ( 5 g , 7 g ) in the shape of a trapezoidal right prism include elements for guiding their longitudinal movement and regulating their position within their respective seats.
4 . The weft feeder for weaving looms according to claim 1 , wherein said compressive force is:
a. greater than a minimum clamping force required to keep an adjustment position of the support shanks ( 5 g , 7 g ) unchanged, in normal operation of the weft feeder, and
b. less than a maximum clamping force still allowing said support shanks ( 5 g , 7 g ) to slide within their respective seats, in an operation to adjust the position of said fixed sectors ( 5 ) and moving sectors ( 7 ).
5 . The weft feeder for weaving looms according to claim 1 , further including quick-tensioning fasteners, bistable between a locked position and an unlocked position, which modify the compressive force exerted by said elastic elements on the support shanks ( 5 g , 7 g ).
6 . The weft feeder for weaving looms according to claim 5 , wherein said modified compressive force:
a. in the locked position is greater than the minimum clamping force required to keep the adjustment position of said support shanks ( 5 g , 7 g ) unchanged, under every operating condition of the weft feeder, and
b. in the unlocked position is less than the maximum clamping force still allowing said support shanks ( 5 g , 7 g ) to slide within their respective seats, in an operation to adjust the position of the fixed and moving sectors ( 5 , 7 ).
7 . The weft feeder for weaving looms according to claim 1 , wherein said elastic elements include wave springs or cup springs ( 10 , 13 ) acting on said support shanks ( 5 g , 7 g ) of the fixed sectors ( 5 ) and the moving sectors ( 7 ) under a certain preload imposed by a closing ring ( 11 , 14 ).
8 . The weft feeder for weaving looms according to claim 7 , further including a flat and rigid shank-pressing ring ( 9 , 12 ), interposed between said elastic elements ( 10 , 13 ) and said support shanks ( 5 g , 7 g ) of the fixed sectors ( 5 ) and the moving sectors ( 7 ).
9 . The weft feeder for weaving looms according to claim 5 , wherein said quick-tensioning fasteners include a locking ring ( 23 ) interposed between said elastic elements ( 10 , 13 ) and said closing ring ( 11 , 14 ), and free to rotate therebetween, the opposing contact surfaces of the locking ring ( 23 ) and the closing ring ( 11 , 14 ) being wavy contact surfaces ( 24 ) which cooperate for changing the axial position of the locking ring ( 23 ) during its rotation, between a position further away and a position closer to the closing ring ( 11 , 14 ) and thereby varying the preload on the elastic elements ( 10 , 13 ).
10 . The weft feeder for weaving looms according to claim 9 , wherein said locking ring ( 23 ) is provided with bulges ( 25 ) which determine limit positions of its rotation against corresponding end stops ( 28 ) formed in said closing ring ( 11 , 14 ).
11 . The weft feeder for weaving looms according to claim 10 , wherein said bulges ( 25 ) are provided with grip holes ( 26 ) for engagement of control levers.