Positioning device of the thread skein-end of the thread for service trolleys for open-end spinning machines
Service trolley for open-end spinning machines equipped for the depositing of the final thread reserve on the exhausted bobbin comprising a thread-guide with a horizontal worm-screw, equipped with a cantilever supporting arm which allows its positioning at different levels and also its axial movement, activated in controlled clockwise/anticlockwise rotation driven by a motor, thus determining both the level and axial coordinate to which the thread is brought and wound onto the tube.
1. A device ( 71 ) for the control and positioning of the thread (F) for automatic service trolleys for spinning units of open-end spinning machines to effect intervention cycles for start-up, re-attachment of the thread, depositing of the final thread reserve and removal of the bobbins onto the single spinning units, said trolley carrying on board organs or groups of organs destined for single or multiple operations of said cycles, said device ( 71 ) comprising a worm screw, with a horizontal axis and parallel to the front of the spinning machine, equipped with a cantilever supporting arm which allows it to be lowered and lifted maintaining the worm screw horizontal and parallel to the front of the spinning machine and in certain positions, and activated in controlled clockwise/anticlockwise rotation driven by a motor, thus determining both the level and the axial coordinate to which the thread is brought, the thread itself being engaged inside the cavity of the threading of the worm screw, which by rotating determines its axial coordinate, characterized in that the device ( 71 ) is equipped with an axial movement organ ( 72 ) of the whole device ( 71 ) so that its worm screw ( 32 ) can be axially and alternatingly moved into a withdrawn position so that the beginning of the worm screw on the internal side of the arm ( 33 ) coincides with the axial coordinate corresponding to the base of the bobbin ( 25 ), or into an extended position so that the free threaded end of the worm screw ( 32 ) coincides with the axial coordinate of the winding end of the bobbin ( 25 ) on the tip of the tube ( 28 ); and in that on the free end of the worm screw ( 32 ) there is a cylindrical cavity ( 73 ) coaxial with the screw in which an extractable and withdrawable cylindrical plug ( 74 ) is housed.
2. The automatic service trolley for spinning units of open-end spinning machines according to claim 1 , characterized in that the axial movement organ ( 72 ) consists of a double-effect pneumatic cylinder, alternatingly fed in one of its two parts with the service fluid for a run equal to the required stroke between two positions.
3. The automatic service trolley for spinning units of open-end spinning machines according to claim 1 , characterized in that activation organ in extension and withdrawal of the plug ( 74 ) consists of a simple-effect pneumatic piston fed with a service fluid under pressure and contrasted by a spring-back.
4. The automatic service trolley for spinning units of open-end spinning machines according to claim 1 , characterized in that the control unit of the trolley is equipped with control means of the length of the thread reserve captured by the suction mouth ( 44 ) determining the number of turns, for which the auxiliary roll ( 42 ) is activated for the unwinding of the bobbin ( 25 ).
5. The automatic service trolley for spinning units of open-end spinning machines according to claim 1 , characterized in that the control unit of the trolley is equipped with control means of the inversion time of the movement of the worm screw ( 32 ) in order to determine the number of turns of the final reserve thread deposited onto the tip of the tube.
6. The automatic service trolley for spinning units of open-end spinning machines according to claim 1 , characterized in that the device ( 71 ) is equipped with activation in rotation of the screw ( 32 ) with a brushless motor ( 35 ) driven in frequency by the control unit of the trolley to obtain angular positions, inversion times and controlled rates in the two rotation directions.
7. The automatic service trolley for spinning units of open-end spinning machines according to claim 1 , characterized in that the device ( 71 ) is equipped with activation in rotation of the screw ( 32 ) with a step-by-step motor ( 35 ) driven in steps by the control unit of the trolley, again obtaining angular positions, inversion times and controlled rates in the two rotation directions.