Process and device for piecing to an open-end friction spinning

Details Process and device for piecing to an open-end friction spinning Process and device for piecing to an open-end friction spinning

1987-04-13

1989-04-11

Petrakes, John

Textiles: spinning, twisting, and twining

Apparatus and processes

Piecing up

57401, D01H 1502

Patent

active

048194204

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

The present invention relates to a process and device for piecing to an open-end friction spinning device having two friction spinning elements which are driven in the same direction and form a nip that is subjected to suction, in which fibers are fed into the nip, into a thread forming zone, from which they are drawn off again in the form of a continuous thread.
According to a process which is known in rotor spinning, the spinning station is supplied with a tube equipped with a winding for piecing, or lead winding when the bobbin is to be replaced (CH-PS No. 618.741), which corresponds with U.S. Pat. No. 4,125,990. To piece thread to the spinning aggregate, the thread of this piecing or lead winding is fed to the spinning aggregate and is then drawn off, whereby the piecing joint reaches the tube.
DE-OS No. 2.501.735 also teaches to separate the thread segment containing the piecing joint from the thread and to aspire it into the opening of a thread draw-off pipe. To achieve this, piecing is effected in this known art with the help of an auxiliary thread supplied from a piecing bobbin which is carried along by a travelling bobbin replacement device. Also, according to this art, the thread is first transferred to the empty bobbin and the thread segment containing the piecing joint is then separated and taken away. This means that in this state of the art a special piecing device is required for bobbin replacement, in addition to the normal piecing device.
It is therefore the task of the present invention to create a device making it possible to effect piecing by a simple method and without requiring a piecing thread. This goal is achieved with practice of this invention in that the fibers fed into the nip are twisted into a fiber bundle and in that said fiber bundle is partially conveyed out of the nip in its longitudinal direction, to be siezed at that point and to be transferred to a winding device. A piecing thread is thus not required, since the fiber bundle produced in the open-end friction spinning device is itself seized and drawn off. Thus a bobbin can be newly started without auxiliary thread which must otherwise be held in readiness on an auxiliary bobbin or on the empty tube, and the device for storing such auxiliary bobbins or devices to supply the piecing winding are not needed. The piecing process, when a bobbin is started, can be thus carried out in the simplest way possible and with little mechanical or time expenditure.
Preferably, the fiber bundle is separated from the remaining thread before the transfer of the thread to the winding device takes place. The piecing joint, constituting a defect, is thus eliminated. The thread which is now transferred to the empty spool thus does not contain any piecing joint. To achieve this goal, no flying bobbin replacement is required, so that maintenance of the spinning device can be combined with bobbin replacement without adverse effect upon the new bobbin.
In a practical version of the process according to invention, fiber feeding is switched off after the formation of the fiber bundle, the fiber bundle is then partially taken out of the nip of the friction spinning elements by pneumatic means, is seized at that point and is secured against twisting at its leading end, whereupon fiber feeding is resumed and the newly produced thread is drawn off from the nip. Through the temporary interruption of fiber feeding, individual fibers are prevented from entering the nip during pneumatic conveying of the fiber bundle, as they would otherwise leave the nip immediately. This interruption of fiber feeding does not effect secure piecing; besides, a possible shortage in fibers can be compensated for by appropriately timing the fiber bundle's staying time in the nip once its leading end has been secured against twisting by controlling the rotational speed of the friction spinning elements, etc.
Pneumatic conveying of the fiber bundle can be carried out in various manners. In a preferred version of the process according to this invent

REFERENCES:
patent: 4107911 (1978-08-01), Yamana et al.
patent: 4125990 (1978-11-01), Stahlecker et al.
patent: 4559774 (1985-12-01), Stahlecker
patent: 4561242 (1985-12-01), Stahlecker
patent: 4563872 (1986-01-01), Stahlecker
patent: 4570430 (1986-02-01), Stahlecker
patent: 4598539 (1986-07-01), Stahlecker et al.

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