Open end spinning rotor comprising a main body and a rotor body

The main body (7) of an open end spinning rotor (3) which comprises a main body (7) and a rotor body (6) wherein the main body is carried by a mounting and drive element and has a substantially radial support surface (72) with a centering surface (70) at its outer edge. A centering surface (61) of the rotor body (6) co-operates with the centering surface 70 of the main body. The centering surfaces (70, 61) in the main body (7) and in the rotor body (6) are in the form of a peripheral groove and a peripheral rib, respectively. The support surface (72) and the centering surfaces (70) of the main body (7) have substantially radial slots (71).

BACKGROUND OF THE INVENTION 
The present invention concerns an open end spinning rotor which comprises a 
main body and a rotor body. The main body is carried by a mounting and 
drive element and has a substantially radial support surface with a 
centering surface at its outer edge. A centering surface of the rotor body 
co-operates with the centering surface of the main body. The rotor body 
has a collecting surface and an open edge at the end which is remote from 
its centering surface. 
The part of the spinning rotor which comes into contact with the fibers to 
be spun is subjected to a considerable amount of wear so that replacement 
of the spinning rotor is required after a certain number of operating 
hours. Although it is known for a spinning rotor to be formed from a 
plurality of components, hitherto it has always been necessary to replace 
the entire unit forming the spinning rotor. Thus for example, a main body 
is pressed onto a drive spindle and into a rotor member main body and 
rotor body can no longer be separated from each other (DOS No. 20 58 340). 
Of course, it has also already been proposed that only a slight press fit 
should be provided between a cylindrical main body and a rotor body which 
is in the form of an insert member (DOS No. 21 30 582). In industrial mass 
production, the precise tolerances required cannot be readily maintained; 
in one case, there is the danger that the pressing is at such a high value 
that, when the rotor body is replaced, the main body also suffers wear 
which results in excessive play which in time does not insure that the 
rotor body is securely held in the main body. In the other situation, 
there is the danger that the play between the rotor body and the main body 
is excessive from the outset so that the rotor body is not securely held 
in the main body from the beginning. Moreover, since the main body extends 
over the entire axial extent of the rotor body, this results in an 
increase in the weight of the spinning rotor, thus requiring a higher 
drive power. 
The problem of the present invention is therefore to provide a composite 
spinning rotor which on the one hand permits ease of replaceability of the 
component which is subjected to wear and which on the other hand permits 
relatively large tolerances without a substantial increase in the weight 
of the spinning rotor. 
SUMMARY OF THE INVENTION 
According to the invention, this problem is solved in that the centering 
surfaces in the main body and in the rotor body are in the form of a 
peripheral groove and a peripheral rib, respectively, and the support 
surface and the centering surface of the main body have substantially 
radial slots. By virtue of the slots, the support surface is resilient and 
receives the rotor body, by way of the centering surfaces, not by a press 
fit but by a clamping action. This permits the rotor body to be securely 
mounted on the main body, without excessive requirements having to be made 
in respect of tolerances. This also does not give rise to the danger of 
damage to or wear of the main body so that the main body has a long 
service life. This is particularly important as the main body generally 
forms a structural unit with the mounting and possibly with the drive 
means. Preferably, the main body has 6 to 8 slots which are of a length of 
from about one-fifth to one-third of the diameter of the main body. 
The slots may be used for producing a reduced pressure in the spinning 
rotor. For this purpose, in accordance with a further feature of the 
invention, the bottom of the rotor body is annular and only partly covers 
the slots. Desirably, the slots in the main body are arranged tangentially 
to an imaginary concentric circle of the main body or are arranged at an 
inclined angle with respect to planes parallel to the axis of the main 
body. 
If the spinning rotor is not required itself to produce a reduced pressure, 
then in accordance with a further feature of the invention, the rotor body 
advantageously has, at its end which is towards the main body, a bottom 
which is parallel to the support surface and which covers the slots. 
The construction according to the invention is suitable not only for 
replacement of the rotor body in the event of wear, but it may also be 
used if the fiber material to be spun is changed and a spinning rotor with 
a different inside diameter is required. For this purpose, according to 
the invention, the rotor body has an inside and outside diameter adapted 
to the fiber material and the centering surface of the main body, 
irrespective of the fiber material, is of a diameter corresponding to the 
largest outside diameter on the rotor body, the rotor body has a flange 
which extends outwardly parallel to the support surface of the main body, 
with a center surface at its outer periphery. The centering surface of the 
rotor body, which, for a maximum diameter of the rotor body, is directly 
at the outer periphery thereof, while, for a smaller diameter of the rotor 
body, it is at the flange, is thus always of the same size. 
For the purposes of exchanging the rotor body for another with a different 
inside diameter however, the rotor body may also have a projection with 
the centering surface, on its side which is towards the main body. 
It is desirable for the rotor body to be produced in the form of a cheap 
throw-away member which is not only economical to manufacture but which 
also requires a small amount of energy for driving it. For this purpose, 
in accordance with a further feature of the invention, the rotor body is 
formed by a sheet metal member which is shaped without cutting machining. 
In this respect, the rotor body is produced by a deep drawing or metal 
pressing process, from a flat or cylindrical sheet metal component. 
The construction designed to carry out the invention will be hereinafter 
described, together with other features thereof.

DESCRIPTION OF A PREFERRED EMBODIMENT 
Referring to FIG. 1, the open end spinning rotor according to the invention 
comprises a rotor body 1, a main body 2 which carries the rotor body 1, 
and a mounting and drive element which carries the main body 1 and which 
is in the form of a shaft 3. 
The rotor body 1 has a collecting surface 11 which can be in the form of a 
groove or a concave channel constructed in known manner, an open edge 12 
at its end which is remote from the main body 2, and between the 
collecting surface 11 and the open edge 12, a sliding surface 13 for the 
fibers. 
The main body 2 has a substantially radial support surface 20 with a 
centering surface 21 which is in the form of an inside peripheral groove 
at its outer periphery. The centering surface 21 thus forms a kind of 
channel for receiving a centering surface 10 at the outer periphery of the 
rotor body 1, the centering surface 10 being correspondingly formed as a 
peripheral rib. The main body 2 has radial slots 22 which are of such a 
length that they impart to the centering surface 21 such a degree of 
resiliency that on the one hand it can deflect radially outwardly when the 
rotor body 1 is pushed onto the main body 2, but on the other hand, it 
always remains bearing against the centering surface 10 of the rotor body 
1. Thus, when the rotor body 1 comes to lie with its bottom 15 against the 
support 20 of the main body 2, the rotor body 1 is firmly held by way of 
the centering surfaces 21 and 10. 
The resilient centering surface 21 of the main body 2 permits easy 
interchangeability of the rotor body 1, with relatively wide tolerances 
being permitted. Nonetheless, the weight of the spinning rotor is not 
substantially increased. 
The rotor body 1 may be of different profiles, surfaces and inside 
diameter. With a change of material or even after wear, it is readily 
possible for the rotor body 1 to be replaced independently of the main 
body 2. For this purpose it is only necessary to apply a pulling force in 
order to pull the rotor body 1 with its centering surface 10 out of the 
centering surface 21 which, when this is done, yields resiliently and 
temporarily deflects radially outwardly. 
If another fiber length is to be spun, another rotor diameter is required. 
So that the entire rotor does not have to be replaced in this case, for 
which purpose the main bodies 2 would also have to be held in store, the 
rotor body 1 may have a uniform outside diameter in respect of its 
centering surface 10, even if the diameter of its collecting surface 11 
varies. For this purpose, the smaller rotor body 1 shown on the left-hand 
side of FIG. 1 has a flange 14 which extends outwardly parallel to the 
support surface 20 of the main body 2 and whose outer periphery is formed 
as the centering surface 10. The dimensions of the main body 2 are matched 
to the largest rotor body 1 which is likely to be used and which does not 
have a flange 14 as referred to above, but instead its outer periphery is 
directly formed as the centering surface 10. Thus, depending on the 
diameter of their collecting surfaces 11, only the smaller rotor bodies 1 
have a flange 14 of different sizes, which the outer periphery of the 
respective flanges always being of the same size and being formed as the 
centering surface 20. In this case, storage is restricted only to the 
rotor bodies of different sizes. 
The rotor body 1 shown in FIG. 1 is produced by a cutting machining 
production process. In order to obtain a rotor body 4 which is of 
particularly small mass, the rotor body may also be in the form of a sheet 
metal component which is shaped without machining cutting, as shown in 
FIG. 2. 
The design of the mounting and drive element is also of no account from the 
point of view of the present invention. Thus, instead of the main body 
being connected to the shaft, the main body 5 may be formed integrally 
with a sleeve 50 which on its inside wall carries permanent magnets 51 
which, in turn, are part of an electric motor. For mounting purposes, a 
mounting trunnion 53 which is carried by the support surface 52 of the 
main body 5 is disposed concentrically in the sleeve 50. 
In order to achieve the minimum size in respect of the rotor body 4 and 
thus the part which is to be replaced and which is to be stocked as a 
wearing component, the rotor body 4 is in the form of a ring with an 
annular bottom 40, as shown in FIG. 2. In order, with such a design, to 
insure that fibers do not become gripped between the rotor body 4 and the 
main body 5, and remain sticking there, the support surface 52 of the main 
body 5 in FIG. 2 has a concentric projection 54 which projects into the 
annular rotor body 4 and which thus projects axially above the bottom 40. 
If desired, the projection 54 can even project into the yarn path (not 
shown) between the collecting surface and the yarn take-off tube (not 
shown) so that the yarn is being taken off rolls against the projection 
54. 
The centering surface on the rotor body may also be arranged at different 
positions. As shown in FIG. 3, on its side which is towards the main body, 
the rotor body 6 has a projection 60 with the centering surface 61 with 
which the centering surface 70 of the main body 7 cooperates. In this 
construction, the main body 7 is very small and permits the replacement of 
rotor bodies 6 with different diameters in respect of their collecting 
surface 62. 
The shape of the annular centering surfaces on the rotor body 1, 4 or 6 and 
on the main body 2, 5 and 7 is of no importance in itself; it is simply 
necessary for the centering surfaces to be matched to each other. Thus, 
the hollow channel-like centering surface 21 for example has a curved 
concave cross-section while the channel-like centering surface 70 has an 
acute-angled cross-section which merges into a convex configuration. The 
centering surface 10 which is in the form of an annular rib has a convex 
cross-section while the centering surface 61 is of an acute-angled 
cross-section. It is also possible for the centering surface of the rotor 
body 1, 4 or 6 to be formed in the manner of a channel into which a 
rib-like centering surface of the main body 2, 5, 7, 8 or 9 then engages. 
It has been found that, depending on the design and the size of the main 
body 2, 5, or 7, it is advantageous for the slots 22, 55 or 71, 
respectively, to be of a length which approximately corresponds to from 
one-fifth to one-third of the diameter of the main body 2, 5 or 7, 
respectively. Depending on the size of the main body 2, 5 or 7, the 
desired degree of resiliency of the support surface 20, 52 or 72, 
respectively, is obtained by from 6 to 8 slots which project in a 
uniformly distributed arrangement from the outside into the support 
surface 20, 52 and 72, respectively. 
Referring to FIGS. 1 to 3, the rotor body 1, 4 and 6 has a bottom 15, 40 
and 63 which is parallel to the respective support surface 20, 52 and 72 
and which covers the slots 22, 55 and 71 in the main body 2, 5 and 7, 
respectively. This presupposes that the reduced pressure in the spinning 
rotor, which is required for conveying the fibers into the spinning rotor, 
is produced by an outside reduced-pressure source. This is frequently 
desirable as the spinning suction is then independent of the speed of 
rotation of the spinning rotor. In practice however, many rotors will also 
be encountered, which produce the spinning suction themselves so that the 
outside reduced-pressure source can be omitted. In this case, the slots 
22, 55 and 71 are not covered by the bottom of the rotory body 1, 4 and 6, 
respectively, but on the contrary, the bottom is then only of an annular 
configuration. 
An embodiment of the spinning rotor according to the invention, of this 
kind, is shown in FIG. 4. In this arrangement, the main body 8 has slots 
80 which project to beyond the inside edge of the bottom 40 (see FIG. 2). 
In order further to increase the fan effect, the slots 80 can be arranged 
tangentially with respect to an imaginary concentric circle 81 on the main 
body 8, in such a way that, in relation to the intended direction of 
rotation 82 of the spinning rotor, the outer end of the slots 80 trails 
their inner end. 
An alernative way of producing a strong spinning suction as a result of the 
rotary movement of the spinning rotor is shown in FIG. 5 which illustrates 
a main body 9. In this embodiment, the slots 90 are arranged at an 
inclined angle with respect to planes which extend parallel to the axis 91 
on the main body 9, in such a way that the ends of the slots 90 which are 
remote from the rotor body 1, 4 and 6, respectively, trail with respect to 
the ends of the slots 90 which are towards the rotor body 1, 4 and 6. 
When the slots 80 or 90 are arranged as shown in FIGS. 4 and 5, the slots 
80 and 90 increase the suction action in the interior of the rotor body 1, 
4 and 6 so that a particularly high suction is produced, in relation to 
the speed of rotation. If a lower suction force is required, it is 
sufficient to provide slots which extend parallel to the axis 91 of the 
main body 9. 
The construction in the form of a composite rotor with a main body 3 which 
is always of the same size, and rotor bodies 4 which are of different 
sizes and which are adapted to the main body 3 by means of a flange 46, 
can be used independently of the specific nature of the connection between 
the main body 3 and the rotor body 4. In this connection, other forms of 
fixing action which are not described herein can be employed. 
The foregoing description shows that the subject of the invention can be 
modified in many ways. Further modifications by the replacement of 
features by equivalents or by combinations of features are possible.