Open-end spinning machines
The present invention relates to open-end spinning machines and is particularly concerned with improvements in the construction of opening rollers for use therein. 
     In an open-end spinning machine hitherto proposed sliver is fed to a rotating opening roller which opens the sliver into separated fibres and conveys them to the entrance of a fibre feed duct. At this point the fibres are removed from the opening roller and conveyed in discrete form in an airstream down the fibre feed duct to the interior of a rotating spinning rotor. The fibres accumulate on the fibre collecting surface of the spinning rotor and are twisted into the tail end of a yarn which is withdrawn from the rotor by yarn delivery means and collected on a yarn package. 
     It is very important for successful yarn production that opening of the sliver is carried out efficiently by the opening rollers. 
     In an opening roller construction hitherto proposed a card type wire provided with saw type teeth is wound helically around the cylindrical outer surface of the roller. It has however been found that rollers of this construction possess certain disadvantages. In particular, when processing certain fibres, particularly when processing blends of natural and synthetic fibres, the working life of the card type wire has proved very short, necessitating frequent maintenance. Furthermore, it has been found that the opening rollers of this construction have the disadvantage that many fibre trapping points are formed in which fibres can become lodged, thus impairing the efficiency of the opening action. 
     In a further opening roller hitherto proposed the construction has included the provision of needles or pins around the outer surface of the roller. It has, however, been found difficult to devise a suitable roller construction of this type which meets the requirements of ease of manufacture whilst providing a roller with a satisfactory operating surface. 
     According to the present invention, there is provided an opening roller for an open-end spinning machine comprising a boss portion, an end wall portion extending radially outwardly from said boss portion at one end thereof, a cylindrical shell portion extending from said wall portion over and in coaxial relation to said boss portion to form an annular cavity between the outer surface of said boss portion, the inner surface of said wall portion and the inner surface of said shell portion, and a plurality of fibre engaging pins located in holes, said pins passing from within the annular cavity through the shell portion and having end portions terminating in points protruding from the outer surface of the shell portion. 
    
    
     Two embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which: 
     FIG. 1 is a diagrammatic side elevation of an open-end spinning machine incorporating an opening roller according to a first embodiment of the present invention, 
     FIG. 2 is a cross-sectional plan view of part of the machine shown in FIG. 1, taken on the line II -- II in FIG. 1 and showing the construction of the opening roller, 
     FIG. 3 is a side elevation partly in section and to an enlarged scale of the opening roller shown in FIG. 1, 
     FIG. 4 is a developed plan of part of the periphery of the roller shown in FIG. 1 illustrating the formation of holes therein, 
     FIG. 5 is a part cross-sectional side elevation of a fragment of the roller shown in FIG. 1, 
     FIG. 6 is a cross-sectional plan view of a part of an opening roller according to a second embodiment of the invention, and 
     FIG. 7 is a cross-sectional side elevation of a fragment of the opening roller shown in FIG. 6. 
    
    
     Referring firstly to FIG. 1, a sliver 1 is forwarded by a nip formed between a feed roller 2 and a feed pedal 3 biased by spring pressure toward the feed roller 2. The sliver emerging from the nip passes to a rotating opening roller 4 which subjects it to an opening action and which conveys the fibres separated from the sliver to the entrance of a fibre feed duct 5. An airstream set up in the fibre feed duct 5 conveys the fibres in discrete form to the interior of a rotating spinning rotor 6. The fibres accumulate at the maximum internal diameter of the spinning rotor 6 where they are twisted into the tail end of a yarn 7 and withdrawn by a pair of delivery rollers 8 and wound on to a package (not shown). 
     Referring now to FIG. 2, the opening roller 4 is mounted within a cavity 9 formed in a housing 10. A cover 11 covers the open end of the cavity. The opening roller 4 is fixedly mounted on one end of a shaft 12 mounted for rotation in suitable bearings (not shown). The opening roller 4 has a boss portion 22, an end wall 13 extending radially from one end of the boss portion to form an end face of the roller and a cylindrical shell portion 15 which provides a location for a plurality of pins 16 which pass through holes in the shell portion 15. Flanges 17 and 27 extend radially from the shell portion 15 at the ends thereof. 
     The cavity formed in the opening roller 4 between the shell portion 15, the end wall 13 and the boss portion 22 is filled with a plastics filler 23 to provide a smooth end face for the opening roller and enhance the balancing characteristics of the roller. 
     At best seen in FIG. 5, each pin 16 is located in the shell portion 15 of the roller in a mounting hole 24 in which it is a clearance fit and in which it is secured by the synthetic resin 28 which fills the clearance between the pin 16 and the hole 24. Each pin 16 is formed by a body portion 18 of constant circular cross-section and a tapering porton 19 protruding from the outer surface of the shell portion 15 and terminating in a point. The extent of protrusion of the pins 16 corresponds to the extent of protrusion of the flanges 17 and 27. The junction of the body portion 18 and the tapering porton 19 is set below the outer surface of the shell porton 15. 
     As will be seen in FIG. 5, each pin 16 is forwardly inclined with respect to the direction of rotation indicated by the arrow. The angle A subtended between the leading edge of the tapering portion of the pin and a radial line passing through the pointed end of the pin is determined by the fibres being processed. For example, it has been found that a suitable angle A for processing certain fibres is 10° and for processing cotton the angle A may be 20°. For processing certain other fibres the pins 16 may be radially arranged or backwardly inclined with respect to the direction of the rotation of the opening roller to provide angle A with a zero or negative value. 
     In the preferred method of construction of the roller the pins 16 are inserted in the holes and held in position therein while the clearances are filled with resin 28, which is then allowed to set. Thereafter, the annular cavity in the roller is filled with a plastics filler 23. Accurate location of the ends of the pins 16 necessary for satisfactory opening of a sliver is thus obtained. 
     The employment of pins as the means to open the sliver enables a better distribution of points of the working surface of the roller than is possible with the former arrangement utilising card type wire. An example of pin distribution is seen in FIGS. 3 and 4, where eight zones Z are provided extending contiguously around the circumference of the shell portion 15 as represented in FIG. 3, each zone having an array of pins as illustrated in FIG. 4. The pins are arranged in rows parallel to the rotary axis of the roller with eight pins in each row spaced at 10 points per inch. Around the circumference of the shell portion 15 there are nine rows of pins spaced at 10 rows per inch in each zone in which the pins of each row are offset from the pins in the preceding or succeeding row. 
     The filler 23 used is coloured according to a predetermined colour code to indicate a particular setting or distribution of pins so that removal of the cover 11 enables a ready visual check to be made of the type of opening roller on the machine. 
     In a further embodiment of the invention shown in FIGS. 6 and 7, the pins 16 are mounted in holes 24 in the same manner and disposition as that of the pins 16 of the roller 4 shown in FIGS. 1 to 5. The filler 23 is, however, omitted and an annular cover plate 21 is used to cover the cavity of the opening roller and as shown forms a planar end face to the roller.