Spinning or twisting device with a pipe shaped element capable of being subjected to negative pressure

A spinning or twisting device in which a yarn is to be back-fed into the bore of a pipe-shaped element subjected to negative pressure in order to repair a yarn break. This pipe-shaped element is made in form of a yarn draw-off pipe of an open-end spinning device or as part of a pneumatic twisting device. A presenting device is moved over and beyond the pipe-shaped element into a yarn inserting position. The end of the pipe-shaped element towards the moving path of the presenting device is provided with a nozzle which is provided, in relation to the bore, on its side towards the yarn inserting position of the presenting device with a yarn support, and on its side away from the yarn inserting position with a yarn insertion groove, oriented in the direction of movement of the presenting device. The bottom of the yarn insertion groove is at a greater distance from the moving path of the presenting device than the yarn support.

BACKGROUND OF THE INVENTION 
The instant invention relates to a spinning or twisting device with a 
pipe-shaped element, subjected to negative pressure, in the bore of which 
a yarn is back-fed, and with a presenting device movable over the 
pipe-shaped element into a yarn inserting position. 
More specifically, in a prior art device, a yarn cut to a preselected 
length is brought by means of a presenting device to a yarn draw-off pipe 
by means of such a device provided for a rotor spinning machine (see 
German Patent No. 34 17 331 Al), where the presenting device is swiveled 
so far over and beyond the yarn draw-off pipe that the yarn end is located 
above the outlet of the yarn draw-off pipe. Negative pressure, produced by 
the negative spinning pressure, is present in the yarn draw-off pipe. To 
enable the yarn to follow the suction air stream thus produced into the 
yarn draw-off pipe, the presenting device is now swiveled back. Due to 
outside influences, however, the yarn end may not be located precisely 
above the outlet of the yarn draw-off pipe so that back-feeding of the 
yarn end into the yarn draw-off pipe is not possible. 
SUMMARY OF THE INVENTION 
It is, therefore, the object of the instant invention to provide a spinning 
device so that reliable insertion of the yarn into the yarn draw-off pipe 
or other pipe-shaped element of the spinning device, e.g., into the 
pneumatic twisting element of an air spinning device, is ensured. 
This object is attained through the invention in that the end of the 
pipe-shaped element near the moving path of the presenting device is 
equipped with a nozzle having a yarn support related to the bore of the 
pipe-shaped element on its side near the yarn inserting position of the 
presenting device, and with a yarn insertion groove oriented in the sense 
of movement of the presenting device on its side away from the yarn 
inserting position. The bottom of the groove is at a greater distance from 
the moving path of the presenting device than the yarn support. Due to 
this design the yarn end in the yarn inserting position of the presenting 
device extends freely outward from the yarn support and follows the air 
stream sucked into the pipe-shaped element without having to overcome 
great frictional influences, or entirely without frictional influences. In 
this way the yarn, safely and simply, enters the nozzle of the pipe-shaped 
element so that when the presenting device moves back the yarn end can be 
sucked back so far into the pipe-shaped element that it is securely held 
there by the negative pressure prevailing in the pipe-shaped element upon 
being released by the presenting device. 
To reduce friction it is possible to have the yarn insertion groove verge 
via a convex surface into the bore of the pipe-shaped element. It has been 
shown that it is especially advantageous for the edge radii of the 
yarn-deflecting edges to measure between 0.5 and 1.5 mm. 
When the free yarn end extends slightly beyond the yarn insertion groove, 
the friction required to deflect the yarn end for insertion into the 
nozzle of the pipe-shaped element is so minimal as to be negligible. 
Nevertheless, it is especially advantageous, in particular for certain 
materials or with relatively weak negative pressures in the pipe-shaped 
element, if the yarn insertion groove length is at least equal to the 
length of the yarn end extending beyond the yarn support when the 
presenting device is in the yarn inserting position. This ensures that the 
free yarn end is without support within the range of the suction air 
stream of the pipe-shaped element of the spinning device and able to enter 
the bore of the pipe-shaped element without having to overcome frictional 
forces. 
In order to also eliminate friction between the yarn end and the bottom of 
the yarn insertion groove, provisions are made in one embodiment of the 
yarn insertion groove that it is given a concave curved bottom extending 
essentially concentrically with the end of the yarn support towards the 
yarn insertion groove. 
In its way to the nozzle of the pipe-shaped element the free yarn end is 
not kept under tension. To ensure, nevertheless, that the end reaches the 
range of the suction air stream prevailing in the nozzle area of the 
pipe-shaped element, provisions are made in a further embodiment of the 
invention for the yarn insertion groove to be preceded (in relation to the 
movement of the presenting device towards its yarn inserting position) by 
a yarn guide feeding the yarn end to the yarn insertion groove. 
The design of the yarn guide may vary. In a preferred embodiment, the 
nozzle is provided with a wall upstream of the yarn insertion groove on 
its side away from the presenting device in the yarn inserting position, 
the wall extending essentially at a right angle to the moving path of the 
presenting device, and the yarn guide is made in form of a notch. 
In another embodiment of the invention the presenting device is provided 
with a guide on its side towards the nozzle, the maximum outer width of 
which is smaller than the maximum inner width of the notch and which can 
be moved through the notch as the presenting device moves into its yarn 
inserting position. 
The notch is preferably asymmetric, and of such configuration that its 
imaginary center line extends increasingly further away from the moving 
path of the presenting device while coming increasingly nearer to the 
pivot axis of the element. This causes the yarn to be drawn increasingly 
deeper into the notch as the presenting device pivots into its yarn 
inserting position and is, thus, held securely in such a position that the 
yarn enters the yarn insertion groove. To ensure that the yarn remains in 
the groove, the notch edge towards the pivot axis of the presenting device 
forms an angle with the moving plane of the presenting device which, 
measured from the inside of the notch, which is not less than 85.degree.. 
However, this angle is preferably greater than 90.degree.. Alternatively, 
or in addition, the notch edge towards the swivel axis of the presenting 
device is undercut for that purpose. 
In another embodiment of the invention the yarn guide is made in form of a 
yarn guiding groove extending along the moving path of the presenting 
device. This guiding groove forcibly orients the yarn end in the direction 
of the yarn insertion groove. 
To facilitate the introduction of the yarn into the guiding groove, the 
latter is provided with a widening on its side away from the yarn 
inserting position of the presenting device. 
Depending on the fiber material used, the free yarn end extending from the 
presenting device deviates to some extent from the desired length. To 
ensure, nevertheless, that the yarn safely enters the bore of the 
pipe-shaped element even though it may lie on the nozzle side away from 
the yarn inserting position of the presenting device, it is advantageous 
for the guiding groove to be provided with a bottom that is a small 
distance from the moving path of the presenting device on its side away 
from the yarn inserting position of said presenting device. The guiding 
groove is thus sloped in the direction of the bore of the pipe-shaped 
element, thus decreasing friction with the yarn, when the free yarn end 
extends beyond the yarn insertion groove. It is especially advantageous if 
the bottom of the guiding groove, in that case, extends essentially along 
the imaginary connecting line between the guiding groove end away from the 
yarn inserting position of the presenting device and the nozzle of the 
pipe-shaped element towards the moving path of said presenting device. 
In another embodiment of the invention, the guiding groove extends beyond 
the yarn insertion groove in the direction of the presenting device in the 
yarn inserting position, whereby the yarn support is part of the guiding 
groove. In this way the yarn end is guided before and after the bore of 
the pipe-shaped element of the spinning device. 
When the presenting device can be pivoted around an axis it is advantageous 
for the yarn to follow a path between the yarn guide and the presenting 
device in the yarn inserting position in such manner as to ensure that the 
yarn will be located above the yarn insertion groove in spite of the 
curved path of the presenting device. For that purpose, it is possible to 
ensure, in an embodiment of the device according to invention, that the 
end towards the yarn insertion groove of the yarn guide preceding the yarn 
insertion groove is at a greater distance from the pivot axis of the 
presenting device than the end of the yarn insertion groove towards the 
yarn guide. In that case, it is preferable for the connecting line between 
yarn guide and the presenting device to intersect a plane formed by the 
end of the pipe-shaped element towards the presenting device and the yarn 
insertion groove in the area of the yarn insertion groove. 
To be able to hold the yarn in its desired course with the presenting 
device mounted so as to be capable of pivoting, it is possible to provide 
for the yarn guide preceding the yarn insertion groove to support, on its 
side towards the pivot axis of the presenting device, an elastic or 
elastically mounted element extending to the moving path of the presenting 
device. 
It is often desirable to locate the yarn monitor as close as possible to 
the spinning element. In order to make this possible with the invention, 
an embodiment of the invention provides for the nozzle to be provided with 
a lateral opening through which the free end of a pivoting yarn feeler 
extends into the open space the bottom of which the yarn insertion groove 
is located. The yarn feeler extends in the direction of the yarn support 
beyond the bore of the pipe-shaped element and receives the free end of 
the yarn feeler between the bore and the yarn support, whereby the recess 
has a depth, with respect to the yarn support, that is greater than the 
sum of the thickness of the diameter of the yarn feeler and of its 
distance from the bottom of the recess. This ensures that the yarn goes to 
the side away from the presenting device and thereby reaches the desired 
side of the yarn feeler for the subsequent spinning process when it is 
presented in front of the nozzle of the pipe-shaped element. 
In another embodiment of such a device, according to the invention, the 
recess is in the form of a chamber which is covered by a wall on its side 
towards the moving path of the presenting device, the wall being 
intersected by the guiding groove extending on both sides of the yarn 
insertion groove. This ensures especially reliable guidance, even in 
combination with a yarn motor. 
The stronger the suction air stream prevailing in the pipe-shaped element, 
the better is the introduction of the yarn end into the bore of said 
pipe-shaped element. In order to avoid having to dispose of an especially 
strong suction air stream and, nevertheless, achieve an intensive action 
of this suction air stream upon the yarn end, the nozzle is provided with 
a cover. In this manner, the intensive action upon the yarn end is 
achieved despite relatively slight negative pressure in the pipe-shaped 
element. In that case, the cover is controllable by the presenting device 
as a function of the latter's position. 
It is often desirable to secure the yarn for a rather long time period in 
the area of the nozzle of the pipe shaped element. To achieve this, the 
yarn support of the nozzle is made in the form of a clamping element in 
another embodiment of the device according to the invention. It is 
possible to move a clamping element that is essentially parallel to the 
moving path of the presenting device towards the first clamping element. 
In order to reduce frictional forces, at least that part of the nozzle 
which receives the yarn insertion groove is made of a synthetic material 
that is not statically chargeable. 
Because of manufacturing imperatives, the nozzle is best not made in one 
piece with the pipe-shaped element of the spinning device but is 
interlockingly connected to the pipe-shaped element and/or the cover 
covering the spinning or twisting device, it being possible to establish 
this connection by means of a snap-in connection. 
The invention can be used with different types of spinning devices. In an 
embodiment, the spinning device is an open-end spinning device, with the 
pipe-shaped element consisting of the yarn draw-off pipe. The object of 
the invention can, however, also be used with spinning devices in which 
the spinning element is a pneumatic twisting element. In this case the 
pipe-shaped element is part of the pneumatic twisting element. 
The invention is simple in construction, is space-saving and can easily be 
installed on existing machines. It ensures reliable presentation of the 
yarn end to the pipe-shaped element and thus ensures its smooth insertion 
there, so that reliability of the subsequent yarn back-feeding process is 
increased.

DETAILED DESCRIPTION OF THE INVENTION 
The invention shall be explained hereinafter, for simplicity's sake, as 
used with an open-end spinning machine which uses spinning rotors, 
friction spinning elements, electrical or electrostatic or purely 
pneumatic spinning elements as its spinning devices. 
The open-end spinning machine is represented in FIG. 1, and only those 
parts which are necessary to understand the invention are shown. In this 
machine, a plurality of open-end spinning devices are installed one next 
to the other, and of these, FIG. 1 only shows covers 10 and 11 of two 
adjoining spinning stations. Covers 10 and 11 each cover a spinning device 
each of which is equipped in the usual manner (and therefore not shown) 
with an open-end spinning element, e.g., a spinning rotor with a fiber 
collection surface. 
An opening device (not shown), to which a fiber sliver is fed by means of a 
feeding device (not shown), precedes the open-end spinning element. The 
opening device opens the fiber sliver into individual fibers which are fed 
to the open-end spinning element and there deposited on the fiber 
collection surface under the effect of a suction air stream (negative 
spinning pressure). The fibers are incorporated into the end of a yarn end 
and are drawn off in form of a yarn 35 through a yarn draw-off pipe 12 
(see FIG. 2) by means of a pair of draw-off rollers 2 consisting in the 
usual manner of a driven draw-off roller 20 and a pressure roller 21 
pressed elastically against it. The draw-off pipe has a mouth 12a and axis 
12b extending therethrough. The drawn-off yarn 35 is conveyed to a winding 
deice 3 with a driven winding roller 30 on which a bobbin 31 lies during 
the spinning operation. The bobbin 31 is supported in a known manner 
between two bobbin arms 32 and 33 by means of which the bobbin 31 is 
brought to bear against the winding roller 30 or is lifted away from it. 
Auxiliary driving devices 34 equipped with a driven auxiliary roll 340 can 
be assigned to the bobbin 31. As such auxiliary driving devices are known, 
the conventional pivot drive, as well as the driving devices, therefore, 
are not shown in the figures for the sake of clarity. 
To be able to suck the yarn end produced by a yarn breakage from bobbin 31 
when such breakage occurs, a suction pipe 4, which can be moved towards 
the bobbin 31, is provided. This suction pipe 4 has a nozzle 40 which 
extends in the receiving position near the bobbin 31 parallel to its 
circumferential line over the entire length of bobbin 31. The suction pipe 
4 is provided with a longitudinal slit (not shown) on its side towards the 
winding device 3 and the spinning device (of which only the cover 11 is 
shown) through which the yarn 35 can emerge from the suction pipe 4 when 
the latter is pivoted back into its position as shown in FIG. 1. 
In the path of the yarn 35 emerging from the suction pipe 4 is a centering 
device 41. In the embodiment shown, the centering device consists of a 
driven spindle with two length segments 410 and 411 of different diameters 
between which a circumferential groove 412 is located. The centering 
device 41 is supported on a pivoting arm 413 which can be brought by a 
drive 414 into different positions around axis 415. 
The segment 410 near the arm 413 has a greater diameter than the segment 
411 on the free end of the centering device 41. In addition, the two 
segments 410 and 411 are provided with threads going in opposite 
directions. The centering device 41 can be driven, as desired, in either 
one of the two directions of rotation by means of a drive 416. 
A presenting device 5 can be moved towards the yarn 35 extending from 
suction pipe 4 via centering device 41 to bobbin 31. The presenting device 
5 essentially consists of a pivoting arm 50 by means of which a pivot 
drive 51 can be pivoted around axis 52. On it free end away from the axis 
52, the presenting device 5 is equipped with a controllable yarn clamp 53 
which, according to FIG. 1, consists of a clamping jaw 530 rigidly 
attached to the arm 50 and of a clamping jaw 531 which can be moved 
against it. This clamping jaw 531 is assigned a drive 532, for instance, 
in the form of a solenoid. 
The presenting device 5 can be pivoted in the direction of arrow P.sub.1 
over the cover 11, over and past the yarn draw-off pipe 12 into the 
position shown in . FIG. 1, i.e., the yarn inserting position, in order to 
present the yarn 35 to the yarn draw-off pipe 12. The yarn inserting 
position is to be understood here to be the position of presenting device 
5 in which the yarn end 350 of the yarn 35 is situated above the nozzle of 
the yarn draw-off pipe 12 and can be introduced into pipe 12. 
The yarn draw-off pipe 12 is provided with a nozzle 7 on its end towards 
moving path 54 (see FIG. 2) of the presenting device 5. The nozzle is 
provided on its side away from the yarn inserting position of the 
presenting device 5 (in relation to the bore 72 of yarn draw-off pipe 12) 
with a yarn insertion groove 70, and on its side towards the yarn 
inserting position with a yarn support 71. As can be seen in FIG. 2, the 
bottom 700 of the yarn insertion groove 70 is at a greater distance from 
the moving path 54 of presenting device 5 than the yarn support 71. The 
reason for this shall be explained further below in greater detail. The 
groove 70 extends perpendicular to the axis 12b of the mouth 12a. 
The yarn insertion groove 70 is essentially oriented in the moving 
direction (arrow P.sub.3) of the presenting device 5. 
A cutting device 8 is provided in the path of the yarn, between the end of 
the longitudinal slit of suction pipe 4 away from bobbin 31 and the 
centering device 41 in such manner that a yarn 35 can be cut off on the 
side of yarn clamp 53 away from bobbin 31. 
In the embodiment shown in FIG. 1 the cutting device 8 consists of a roller 
80 which serves as an anvil and with which a cutting edge 81, associated 
for that purpose with a drive 82, interacts. For reason of clarity the 
cutting device 8 has been shown in FIG. 1 turned away slightly from its 
actual position. 
Appropriate drive and control elements are, of course, provided for the 
different elements described, and these can be of a design in general use, 
so that they are not shown in the figures for the sake of clarity. The 
drive and control elements are controlled by a control device which is not 
shown and which also controls the entire piecing process. Other 
conventional parts, such as for example a yarn guide, a yarn tension 
compensating hoop, etc. are omitted in order to simplify the illustration 
in the drawings. 
The device's structure having been described, its operation shall now be 
explained in further detail: 
During normal spinning operation the yarn 35, spun in the normal manner in 
the spinning device, is fed by means of the draw-off rollers 2 to bobbin 
31 driven by roller 30 and is wound up on the bobbin, with yarn 35 being 
held under constant tension by means of yarn tension compensating means 
(not shown) and is distributed pendulum-fashion by a yarn guide (not 
shown). 
If yarn breakage occurs, the open-end spinning device is stopped in the 
known manner so that fibers can no longer reach the fiber collection 
surface of the open-end spinning element. Furthermore, the bobbin 31 is 
lifted from winding roller 30 by known means which are, therefore, not 
shown, so that bobbin 31 is also stopped. 
For the piecing of yarn 35 the open-end spinning element is cleaned in a 
known manner, whereby it is as a rule temporarily braked, possibly even to 
a full stop. 
To be able to back-feed the end of the torn or broken yarn 35 from bobbin 
31 of winding device 3 to the fiber collection surface of the open-end 
spinning element, the end must be drawn off from bobbin 31. For that 
purpose the bobbin 31, which is lifted from winding roller 30, is then 
contacted by the auxiliary driving roller 340 of the driving device 34. 
The auxiliary driving roller 340 is driven by conventional means in a 
direction that is opposite to that of normal winding. Furthermore, in 
coordination with the movement bringing the auxiliary driving device 34 
into action, the suction pipe 4 is pivoted against bobbin 31 and a 
negative pressure is produced in it. The yarn end is thereby sucked into 
the suction pipe 4. When a sufficient length of yarn 35 has entered 
suction pipe 4 so that it is securely held by the suction air stream 
prevailing here, suction pipe 4 is pivoted away from bobbin 31, whereby a 
section of yarn 35 emerges from the suction pipe 4 through its 
longitudinal slit, but is still held in the suction pipe 4 by its free 
end. 
Yarn 35, emerging from suction pipe 4, reaches the centering device 41 
which is then driven so that yarn 35 enters its circumferential groove 
412. Yarn 35 thereby follows a defined yarn path between the slit end of 
suction pipe 4 away from bobbin 31 and the centering device 41. 
The presenting device 5 is then at first in a starting position 5a. It is 
now pivoted in the direction of arrow P.sub.1. In this process the yarn 
clamp 53 crosses the yarn path of yarn 35 which extends from the slit end 
in suction pipe 4 to the centering device 41, seizes and clamps said yarn 
35 between its clamping jaws 530 and 531 which can be first opened to 
grasp yarn 35, and then be closed when yarn 35 has been received. 
The presenting device 5 then reaches its cutting position, whereby yarn 35 
enters the effective range of the cutting device 8. The cutting device is 
now actuated. Yarn 35, which is cut in this manner has, therefore, a 
defined yarn length between yarn clamp 53 and cutting device 8. 
Once yarn 35 has been cut to this defined yarn length the presenting device 
5 is moved on towards the open-end spinning device (see cover 11) until it 
is in its yarn inserting position shown in FIG. 1, whereby the yarn clamp 
53 is guided over the nozzle of yarn draw-off pipe 12. The free yarn end 
350 of the shortened yarn 35 thereby enters the yarn insertion groove 70 
extending parallel to the moving direction of the presenting device 5 (see 
arrow P.sub.3), thus ensuring that yarn 35 enters the range of the suction 
air stream produced by the negative spinning pressure in the yarn draw-off 
pipe 12. Yarn 35 rests on the yarn support 71 between the yarn insertion 
groove 70 and the presenting device 5 in yarn inserting position. 
When presenting device 5 has reached its yarn inserting position (see FIG. 
1), yarn end 350 extends from the yarn clamp 53 to above the yarn 
insertion groove 70. 
The negative pressure produced in the bore 72 of nozzle 7 by the negative 
pressure prevailing in the spinning device produces a suction air flow in 
direction of arrow P.sub.2 (as seen in FIG. 3). The yarn end 350 is now 
subjected to that flow. Because of the slit configuration of the yarn 
insertion groove 70 this suction air flow acts upon yarn end 350 only in 
the area of the yarn insertion groove 70. 
As was already mentioned in connection with FIG. 2, the bottom 700 of the 
yarn insertion groove 70 is at a greater distance from the moving path 54 
of the presenting device 5 than the yarn support 71. The yarn end 350, 
therefore, hangs freely in the air and can follow unhindered the suction 
air flow prevailing in the yarn insertion groove 70 in direction of arrow 
P.sub.2 and thus enters the bore 72 of nozzle 7. 
The presenting device 5 now returns in the direction of arrow P.sub.4 (FIG. 
1) and stops in the transfer position above the nozzle 7. At the same time 
yarn end 350 is sucked deeper and deeper into the yarn draw-off pipe 12 as 
a function of the pivoting motion of the presenting device 5. In the 
transfer position of the presenting device the yarn clamp 53 is opened so 
that yarn 35 is released by presenting device 5. 
The yarn 35, which is sucked in direction of the fiber collection surface 
of the not-shown open-end spinning element, lies on the fibers which, in 
the meantime, have again been fed to the fiber collection surface, and for 
this a yarn reserve not shown) constituted previously during the 
back-feeding of yarn 35 into suction pipe 0, may have to be used up. Yarn 
draw-off is then the resumed in the known manner and yarn 35 is wound up 
on bobbin 31 which is again lowered on the winding roller 30 and separated 
from the auxiliary driving device 34 in the meantime. As a result of the 
centering device 41 being suitably driven in a direction opposite to the 
prior direction of rotation, which was needed to center yarn 35, the yarn 
35 is moved over segment 411 to its free end in synchronization with the 
release and back-feeding of yarn 35, and is thrown off segment 411. 
The yarn end 350 to be fed back to the spinning element can be prepared in 
a known manner for piecing. Cutting by means of a cutting device 8 can be 
quite sufficient, for example. But it may also be tapered in the 
conventional manner by means of a preparation device which is not shown 
here. Such a tapered yarn end 350 is shown in FIG. 3. 
It goes without saying that if the spinning element is a rotating one, 
e.g., a spinning rotor, it must again be started up in coordination with 
the piecing process. 
A comparison between FIGS. 2 and 3 shows that the yarn insertion groove 70 
can be designed in different ways. In the embodiment shown in FIG. 2 the 
yarn insertion groove 70 has essentially a rectangular profile in 
cross-section, with the edges 73 and 74 which deflect yarn 35, and to 
which the transition edge into bore 72 of the nozzle 7 also belongs, being 
convex surfaces, i.e., have a rounded profile. It has been shown to be 
especially advantageous if these rounded edges 73 and 74 have a radius 
measuring from 0.5 to 1.5 mm. It has been shown that when radii are 
smaller, friction produced by the roughness of the yarn can become so 
great that reliable introduction of the yarn end 350 into bore 72 is no 
longer ensured. On the other hand, it has been shown that when the radius 
of edges 73 and 74 is too great, the enveloping friction has a detrimental 
effect and may also hinder or impede the insertion of the yarn end 350 
into bore 72 of the nozzle 7. Depending on the material used, this may 
occur with radii greater than 1.5 mm. 
As a rule, it is desirable to coordinate the length of the yarn end 350 by 
suitable selection of the cutting position of the presenting device 5, on 
the one hand, with the length of the yarn end 350 in the area of nozzle 7 
through suitable selection of the yarn inserting position of the 
presenting device 5 and, on the other hand, in such manner that the yarn 
end 350 extends from the yarn support 71 freely to above the yarn 
insertion groove 70. The yarn insertion groove 70 is of a length that is 
at least as great as the length of yarn 350 extending beyond the yarn 
support 71. 
Depending on the material used, this goal can, however, not always be 
reached precisely without having to give nozzle 7 excessive dimensions. 
For example, if the yarn end 350 cut by means of the cutting device 8 must 
also undergo a preparation process to give yarn end 350 a tapered 
configuration, a somewhat greater yarn length must be fed back to the 
fiber collection surface than if yarn 35 is only shortened by cutting in 
order to achieve a sufficient strength in the piecing joint. In that case 
the yarn inserting position of the presenting device 5 must be selected so 
that yarn end 350 extends beyond the yarn insertion groove 70. 
As mentioned above, the yarn insertion groove 70 is of such a dimension, 
and coordinated with the movement of the presenting device 5 in such a 
manner, that, normally, the yarn end 350 resting on the yarn support 71 
hangs freely in the air above the yarn insertion groove 70. The yarn 
insertion groove 70 is, therefore, of such length and of such depth that 
yarn end 350 does not come into contact with the walls of the yarn 
insertion groove 70 as it is deflected in the direction of bore 72, 
excepting, at the most, the lateral walls of the yarn insertion groove 70 
which guide the yarn end 350. 
According to FIG. 3 the yarn insertion groove is provided with a curved 
bottom. The curve is such in that case, that bottom 700 of the yarn 
insertion groove 70 is essentially concentric with the end of the yarn 
support 71 towards the yarn insertion groove 70. 
FIG. 4 shows a nozzle 7 provided with a recess 75 which, in turn, is 
provided with an opening 751 (see FIG. 7) on the side, so that a 
swivel-mounted yarn feeler 9 is able to reach into the recess 75 from the 
side. The yarn insertion groove 70 is provided in the bottom 750 of recess 
75. Recess 75 reaches on its side away from the yarn support 71 at least 
as far as the yarn insertion groove 70. On its side towards the yarn 
support 71 the recess 75 extends so far beyond the yarn insertion groove 
70 and bore 72 that the yarn feeler 9 is pivoted into its rest position 
and finds room between the yarn support 71 and the bore 72. The recess 
also has a depth h (see FIG. 5) which is greater than the sum of the 
diameter d or of the thickness of yarn feeler 9 and the distance a between 
said yarn feeler 9 and bottom 750 of recess 75. This ensures that the 
deflection of the yarn into the bore 72 of nozzle 7, and thereby also into 
the bore of the yarn draw-off pipe 12, can be carried out without being 
impaired by the yarn feeler 9, so that the latter can be installed in 
great proximity to the spinning element. 
In the embodiment shown in FIGS. 4 to 6 and 8 a yarn guide 76 is installed 
before the yarn insertion groove 70 (with reference to the presenting 
movement (arrow P.sub.3) of presenting device 5). Guide 76 ensures that 
the yarn end 350 is sucked into the yarn insertion groove 70 and into the 
range of concentrated suction air flow being aspired into bore 72. 
In the example shown, a wall 760 is provided on the nozzle 7 on its side 
away from the presenting device 5 in yarn inserting position, the wall 
being oriented transversely to the direction of movement of said 
presenting device 5 (arrow P.sub.3) in FIG. 4, the yarn guide being formed 
in said wall 760. It has the form of a notch 761 which tapers as its 
distance from the moving path 54 of the presenting device 5 increases. 
FIG. 1 shows the presenting device 5 mounted on a pivoting axis 52. The 
presenting device 5 executes a circular movement, causing the position of 
yarn 35 in relation to the nozzle 7 to be changed also. 
To ensure that yarn 35, extending from presenting device 5 to notch 761, 
gets into the yarn insertion groove 70, notch 761 is provided on the side 
away from the axis 52 of the presenting device 5, considering a plane e 
formed by bore 72 of nozzle 7 and the yarn insertion groove 70. The yarn 
guide 76 constituted by notch 761 is located at a greater distance from 
the axis 52 of the presenting device 5 than the end of yarn insertion 
groove 70 (FIG. 8) towards notch 761. This makes it possible for the 
course of the yarn to remain in the zone of influence of the suction air 
stream applied to the yarn draw-off pipe 12 in spite of the circular path 
of the presenting device 5, even when the latter has reached its yarn 
inserting position. This suction air stream can act with special intensity 
on the yarn end 350 when the connecting line 35a between the yarn guide 76 
in form of notch 761 and the presenting device 5 intersects the plane or 
surface e which is defined by bore 72 (or by the end of yarn draw-off pipe 
12 towards the moving path 54 of the presenting device 5) and the yarn 
insertion groove 70 in the longitudinal zone of yarn insertion groove 70. 
This ensures that the yarn end 350 will still extend beyond the yarn 
insertion groove 70, even when it has passed presenting device 5 and 
nozzle 7 and is brought into its yarn inserting position, so that yarn end 
350 is certain to enter yarn insertion groove 70 and also yarn draw-off 
pipe 12 after leaving notch 761. It goes without saying that this offset 
of the yarn guide 76, which may be in form of a notch 761 for example, 
must be greater or smaller depending on the position in which it is built 
(in a horizontal or more or less inclined plane). 
According to FIGS. 5 and 6 the notch 761 is of asymmetric design so that a 
straight line (center line g) cutting notch 761 in half is at such a slope 
that as the distance from the moving path 54 of presenting device 5 
increases, it comes closer to its pivoting axis 52. In this way, the 
presenting device 5 pulls yarn 35 ever deeper into notch 761 as it moves 
into its yarn inserting position so that yarn 35 is secured in that 
position and is sure to enter the yarn insertion groove 70 with its yarn 
end 350. 
The certainty with which yarn 35 is prevented from leaving notch 761 when 
this is not wanted can be further increased by inclining the lateral edge 
768 of notch 761 towards the axis 52 of presenting device 5 in relation to 
the moving plane (moving path 54) of presenting device 5 so that the angle 
.alpha. between the plane lying in the moving path 54 of presenting device 
5 and lateral edge 768 (as seen from the inside of notch 761) is not less 
than 85.degree., and preferably more than 90.degree.. In addition it is 
possible to under cut this edge 768 and to provide it with a stop 762 
which securely holds back yarn 35 so that yarn end 350 cannot leave notch 
761 laterally, in the direction of the axis 52 of presenting device 5. 
According to FIG. 5 the presenting device 5 is provided with a guide 55 
consisting of two elements 550 and 551 on its side towards the nozzle 7 
which are inserted through notch 761 when the presenting device 5 moves 
into its yarn inserting position. For that purpose, the maximum outside 
width W.sub.a of guide 55 is smaller than the clear or inside width 
W.sub.i of notch 761. Thanks to guide 55, the yarn end 350 is placed into 
groove 761 in which yarn end 350 is securely held due to the geometry of 
notch 761. 
The guide 55 and the yarn guide 76 can be designed in different ways, e.g., 
in form of a groove, a notch, two bolts, etc. FIG. 3 shows that instead of 
a notch 761, a guiding groove 764 constituting yarn guide 76 and extending 
in the moving direction (P.sub.3) of the presenting device 5 is located 
before the yarn insertion groove 70. In order to introduce the yarn end 
350 securely into the guiding groove 764 when presenting device 5 is moved 
beyond nozzle 7, the guiding groove 764 can be widened in the manner of a 
funnel on its side away from the yarn inserting position of presenting 
device 5 (see widening 765 in FIG. 7). 
When the presenting device 5 is designed with a guide 55, narrow tolerances 
must be observed to ensure that the guide can reliably pass through notch 
761. FIG. 1 shows another embodiment in which the yarn is securely guided 
into notch 761 without the necessity of especially considering tolerances. 
According to FIG. 1 and elastic element in form of a lobe 763 extends from 
wall 760 which contains the yarn guide 76 (notch 761) preceding the yarn 
insertion groove 70 in the direction of the moving path 54 of presenting 
device 5. This lobe 763 ensures that yarn 35 is faultlessly inserted by 
presenting device 5 into notch 761. 
Lobe 763 reaches at least as far as into proximity of the moving path 54 of 
presenting device 5, and in the shown, preferred embodiment, even as far 
as into the moving path 54 of presenting device 5, so that yarn end 350 
has absolutely no other possibility than to enter notch 761. 
The elastic element can also be designed differently, in form of an elastic 
pin. Instead of an elastic element, it is also possible to provide a 
retaining element which, although itself of rigid construction, is, 
however, mounted elastically so that it is able to evade the presenting 
device 5. 
The bottom 766 of guiding groove 764 (see FIG. 3) need not extend parallel 
to the moving path 54 of presenting device 5. The feeding of yarn end 350 
to yarn insertion groove 70 and bore 72 of nozzle 7 is facilitated if the 
bottom 766 is at a shorter distance from the moving path 54 of presenting 
device 5 on its side away from the yarn inserting position of presenting 
device 5 than on its side towards the yarn inserting position. If the 
bottom 766 slopes down in direction of bore 72, this facilitates the 
insertion of yarn end 350 into bore 72, while the deflection of yarn end 
350 in direction of yarn insertion groove 70 can start before the 
presenting device 5 has reached its end position, i.e., its yarn inserting 
position. A design (see FIG. 3) in which the bottom 766 of guiding groove 
764 follows essentially the connecting line y between the end 764' of the 
guiding groove 764 away from the yarn inserting position of presenting 
device 5 and the opening of the pipe-shaped element (e.g., yarn draw-off 
pipe 12) towards the moving path 54 of presenting device 5, whereby bore 
72 of nozzle 7 can take the place of this opening, has been found to be 
especially advantageous. 
As the preceding description shows, the spinning device can be modified in 
many different ways within the framework of the instant invention. It is, 
for example, possible to replace certain characteristics by equivalents or 
to combine them in a different manner with additional characteristics. 
Neither is it absolutely necessary for the pipe-shaped element, which can 
be subjected to negative pressure, to be in form of a yarn draw-off pipe 
12 of an open-end spinning device. If a spinning or twisting device with a 
pneumatic twisting element is involved, the latter or part thereof, can 
constitute the pipe-shaped element in the sense of the instant invention. 
Several individual yarns can be twisted together in a known manner by 
means of this twisting element, or a twisted yarn can be produced in that 
a drawn fiber sliver is twisted by the twisting element and maintained in 
the twisted state through the incorporation of fibers previously spread 
away. 
It is necessary with such a spinning device, as well as with a twisting 
device, to feed the twisted or spun yarn back to the twisting element when 
the yarn has broken for piecing purposes. In order to be able to subject 
this twisting element to negative pressure, it is either provided with 
compressed-air bores or jets inclined in the direction opposite to that of 
the normal yarn draw-off, or else an element capable of being subjected to 
negative pressure can be attached to the side of the twisting element 
which constitutes its feeding side during normal production to suck back 
the yarn end. 
Here, too, the same problems exist as for back-feeding of the yarn 35 into 
the yarn draw-off pipe 12 of an open-end spinning machine. Therefore, a 
presenting device 5 as well as a nozzle 7 of the type described can also 
be used with such a twisting or spinning device with a pipe-shaped 
spinning or twisting element capable of being subjected to negative 
pressure, i.e., a pneumatic twisting element. 
The device can be designed so that the elements of the spinning o twisting 
device required for work during normal production (twisting or spinning) 
are installed at every work station. However, the elements which are 
needed only to initiate the normal working process, e.g., piecing, can be 
installed on a service unit capable of traveling alongside a plurality of 
work stations of the same type. 
If, however, only one work station is provided, for example, in a testing 
device, it goes without saying that the elements needed for the normal 
operation as well as for the start-up must be installed at the work 
station itself. 
The presenting device 5 can also be of different design and move in a 
different manner than shown. It can, for example, be capable of pivoting 
around a horizontal axis instead, as shown, around a vertical axis; 
however, it can also be mounted in a slid-like guide run so that it can be 
shifted. Depending on the type of movement of presenting device 5 (linear 
or circular), the surface 4 can be flat or curved. 
The yarn clamp 53 can also be made differently, e.g., in the form of two 
rollers that are driven in the direction of rotation, or, also, in the 
form of one roller capable of being driven and one non-rotating 
counter-piece. Instead of a yarn clamp 53 it is, however, also possible to 
provide a sieve which can be subjected to negative pressure so that yarn 
35 is sucked by the negative pressure against the sieve and thus held for 
as long as the negative pressure is maintained. 
The cutting device 8 can also be made differently, e.g., in the manner of 
scissors. 
In the embodiment shown in FIG. 2, the yarn support 71 is made in the form 
of a clamping element towards which another clamping element 710 can be 
brought and which can be moved parallel to the moving path 54 of 
presenting device 5. 
This additional clamping element 710 is made in form of an elastic lobe in 
the embodiment shown. Other designs, e.g., in form of a band loop made of 
rubber, or in form of a rigid or only slightly deformable block or 
plate-shaped, elastically mounted stop are also possible. 
By means of such clamping elements 71 and 710 it is possible to use nozzle 
7 also with mass piecing when a plurality of adjoining spinning stations 
of the same type are stopped together and are again pieced together. 
When this plurality of work stations (spinning or twisting stations) are 
stopped, the different elements of this work station are stopped in a 
known, synchronized manner so that the yarn ends 350 are pulled out at 
least to a great extent from the yarn draw-off pipe 12 or other 
ring-shaped element at the different work stations. To ensure that the 
yarn end 350 cannot leave this position during the stoppage of the 
machine, when the pipe-shaped element is not subjected to negative 
pressure, the mobile clamping element 710 is moved in direction of arrow 
P.sub.3 beyond nozzle 7 and is brought to bear against the clamping 
element (yarn support 71). 
When the machine is to be started up again after a pause, the different 
elements of the work stations are switched on one after the other in a 
known, synchronized manner. In coordination therewith, the clamping 
element 710 also returns into its rest position where it is outside the 
moving path 54 of presenting device 5. The free yarn end 350 which is in 
the area of influence of the reactivated suction air stream of the 
pipe-shaped element is sucked into same so that the subsequent operation 
takes place in the known manner. 
Since the clamping element 710 liberates the moving path 54 of presenting 
device 5 during piecing, the latter can operate in the manner described 
when disturbances occur, without being hindered by the clamping element 
710. 
FIG. 7 shows another embodiment of a nozzle. The nozzle 7 in this 
embodiment is made in two parts and consists of a lower part 77 which 
receives the recess 75 as well as the yarn insertion groove 70, and of a 
cover-like upper part 78 in which a guiding groove 767 is located which 
extends (in relation to the moving direction of the presenting device 5 in 
its yarn inserting position indicated by arrow P.sub.3) from the 
presenting end of nozzle 7 via yarn insertion groove 70 and beyond it, in 
the direction of the yarn inserting position of presenting device 5, to 
the removing end of nozzle 7. The guiding groove 767 verges into the yarn 
insertion groove 70 and the yarn support 71 is constituted by the bottom 
of guiding groove 767 and is, therefore, a part thereof. 
In a similar manner it is also possible, in order to repair a yarn 
breakage, for the presenting device 5 to pull the yarn end 350 over and 
beyond bore 72 so that yarn end 350 is sucked back into bore 72 only with 
the return movement of presenting device 5. For this it is merely 
necessary that an appropriate configuration of the nozzle 7 causes the 
suction air stream to be of such intensity in the area of yarn end 350 
that it is able to pull yarn end 350 back. For that reason deflection 
edges near the yarn support 71 must be designed in the same manner as the 
edges 73 and 74 (see FIG. 2). 
In order to reduce retention of the yarn end 350 at nozzle 7 as much as 
possible, the friction values, adhesion values, etc., must be lowered. 
This is achieved first of all by giving the appropriate configuration to 
the surfaces, edges and profiles (of the grooves) of nozzle 7 which come 
into contact with the yarn end 350. In addition to the selection of an 
appropriate configuration for the surfaces, and edges coming into contact 
with the yarn end 350, the material also plays a major role. It is 
advantageous if at least the part of nozzle 7 which receives the yarn 
insertion groove 70 and extends to bore 72 is made of a synthetic material 
which cannot be statically charged. To achieve this, the yarn insertion 
groove 70 can be located in an insert of nozzle 7, or the basic body of 
nozzle 7 can be made of such a synthetic material while the support parts 
are made of a different material. An embodiment shall be described further 
below through FIG. 7. It can also be advantageous for the yarn support 71 
to be made similarly of such a non-chargeable synthetic material. 
Another possibility to intensify the air flow in the area of bore 72 (see 
FIG. 5) and, in particular, of the yarn insertion groove 70 or of the 
guiding groove 767 is indicated by broken lines in FIG. 7, whereby the 
guiding groove can be covered by a cover 6. This cover 6 is normally 
located outside the moving path 54 of presenting device 5 and is brought 
to the nozzle 7 once the presenting device 5 has passed nozzle 7. 
Cover 6 can be controlled as desired for that purpose, e.g., by the control 
device (not shown) which also controls the entire piecing process (in 
open-end spinning devices). However, it can also be coupled to presenting 
device 5 for movement, and when the presenting device 5, being pivoted 
away from its starting position, has arrived to a location above the 
nozzle, it can be uncoupled so that the presenting device 5 alone 
continues into its yarn inserting position while cover 6 remains at nozzle 
7 and covers it. As the presenting device 5 is pivoted back, the cover 6 
is again coupled to presenting device 5. 
It is, however, also possible to have the presenting device 5 actuate a 
switch or a rod system after passing nozzle 7 (in its movement into yarn 
inserting position), causing cover 6 to be brought from its rest position 
into its operating position in which it covers nozzle 7. The actuation of 
the switch or of the rod system is carried out as a function of the 
presenting device 5 at the earliest when the latter has passed the nozzle 
7 in the direction of yarn inserting position, and at the latest when 
presenting device 5 has reached its yarn inserting position. Inversely, 
the presenting device 5 causes the opening of the nozzle 7 in its return 
movement in a time-coordinated manner so that when presenting device 5 
reaches nozzle 7, the cover 6 has again opened the moving path 54 of 
presenting device 5. 
As shown in FIG. 7, the recess 75 (see FIG. 4) can be covered by a 
cover-like part 78 on its side towards the moving path 54 of presenting 
device 5 so that recess 78 is closed like a chamber in nozzle 7. The side 
of the cover-like part 78 of the nozzle 7 towards the moving path 54 of 
presenting device 5 is then intersected by the guiding groove 767 
extending on either side of the yarn insertion groove 70. The cover of the 
chamber-like recess 75 in turn causes intensification of the air flow in 
the area of yarn insertion groove 70 and also of guiding groove 767. 
The nozzle 7 can, in principle, be connected as desired to the yarn 
draw-off pipe 12 or to some other pipe-shaped element. So that the 
tolerances to be observed need not be too narrow, provisions are made 
according to FIG. 2 for the nozzle 7 to be merely connected interlockingly 
to the yarn draw-off pipe 12 or other kind of pipe-shaped element, e.g., 
by a catch or clip connection 120 that can be opened rapidly if necessary. 
To improve the hold of the nozzle 7 the latter can, in addition (or 
instead), be connected in a similar manner (i.e., by means of a detachable 
catch or clip connection 110) to the cover 10 or 11.